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Sample records for volume total pore

  1. Unified method for the total pore volume and pore size distribution of hierarchical zeolites from argon adsorption and mercury intrusion.

    Science.gov (United States)

    Kenvin, Jeffrey; Jagiello, Jacek; Mitchell, Sharon; Pérez-Ramírez, Javier

    2015-02-03

    A generalized approach to determine the complete distribution of macropores, mesopores, and micropores from argon adsorption and mercury porosimetry is developed and validated for advanced zeolite catalysts with hierarchically structured pore systems in powder and shaped forms. Rather than using a fragmented approach of simple overlays from individual techniques, a unified approach that utilizes a kernel constructed from model isotherms and model intrusion curves is used to calculate the complete pore size distribution and the total pore volume of the material. An added benefit of a single full-range pore size distribution is that the cumulative pore area and the area distribution are also obtained without the need for additional modeling. The resulting complete pore size distribution and the kernel accurately model both the adsorption isotherm and the mercury porosimetry. By bridging the data analysis of two primary characterization tools, this methodology fills an existing gap in the library of familiar methods for porosity assessment in the design of materials with multilevel porosity for novel technological applications.

  2. Prediction total specific pore volume of geopolymers produced from waste ashes by fuzzy logic

    Directory of Open Access Journals (Sweden)

    Ali Nazari

    2012-04-01

    Full Text Available In the present work, total specific pore volume of inorganic polymers (geopolymers made from seeded fly ash and rice husk bark ash has been predicted by fuzzy logic. Different specimens, made from a mixture of fly ash and rice husk bark ash in fine and coarse form together with alkali activator made of water glass and NaOH solution, were subjected to porosimetry tests at 7 and 28 days of curing. The curing regime was different: one set of the specimens were cured at room temperature until reaching to 7 and 28 days and the other sets were oven cured for 36 hours at the range of 40-90 °C and then cured at room temperature until 7 and 28 days. A model based on fuzzy logic for predicting the total specific pore volume of the specimens has been presented. To build the model, training and testing using experimental results from 120 specimens were conducted. The used data as the inputs of fuzzy logic models are arranged in a format of six parameters that cover the percentage of fine fly ash in the ashes mixture, the percentage of coarse fly ash in the ashes mixture, the percentage of fine rice husk bark ash in the ashes mixture, the percentage of coarse rice husk bark ash in the ashes mixture, the temperature of curing and the time of water curing. According to the input parameters, in the fuzzy logic model, the pore volume of each specimen was predicted. The training and testing results in the fuzzy logic model have shown a strong potential for predicting the total specific pore volume of the geopolymer specimens in the considered range.

  3. Trihalomethane, Dihaloacetonitrile, and Total N-nitrosamine Precursor Adsorption by Carbon Nanotubes: The Importance of Surface Oxides and Pore Volume

    Science.gov (United States)

    Needham, Erin Michelle

    As drinking water sources become increasingly impaired, enhanced removal of natural organic matter (NOM) may be required to curb formation of disinfection byproducts (DBPs) upon chlor(am)ination. While carbon nanotubes (CNTs) can adsorb NOM, their properties for DBP precursor adsorption have not been elucidated. Nine types of CNTs were assessed for trihalomethane (THM), dihaloacetonitrile (DHAN), and total N-nitrosamine (TONO) precursor adsorption. Batch isotherm experiments were completed with lake water and, to simulate an impaired condition, effluent from a wastewater treatment plant (WWTP). Adsorption varied with CNT type and dose, with TONO precursors having the highest percent removals from WWTP effluent (up to 97%). Physicochemical properties of CNTs were characterized by gas adsorption isotherms and x-ray photoelectron spectroscopy and numerical models were developed to identify CNT properties driving DBP precursor adsorption. The models fits were strong (R2 > 0.92) and indicated removal of the three precursor types increased with percent carboxyl groups (p adsorption of DBP precursors and demonstrate the potential of CNTs for TONO precursor removal.

  4. Active Pore Volume in Danish Peat Soils

    DEFF Research Database (Denmark)

    Forsmann, Ditte M.; Kjærgaard, Charlotte

    2012-01-01

    Phosphorus release within the soil matrix caused by the changed redox conditions due to re-establishment of a riparian wetland can be critical for the aquatic environment. However, phosphorous released in the soil will not always result in an immediate contribution to this loss to the aquatic...... is not actively transported out of the system, but is only transported via diffusion, which is a very slow process. Thus it is interesting to investigate the size of the active pore volume in peat soils. The hypothesis of this study is that the active pores volume of a peat soil can be expressed using bulk...

  5. Active Pore Volume in Danish Peat Soils

    DEFF Research Database (Denmark)

    Forsmann, Ditte M.; Kjærgaard, Charlotte

    2012-01-01

    cm3 intact soil samples. Finally, breakthrough of tritium (3H2O) was used to construct breakthrough curves for each peat soil, which indicates the flow pattern in the soil. A mobile-immobile domain model (MIM-model) in CXTFIT was used to derive parameters describing the size of the immobile...... and mobile domains as well as the exchange between the two domains. Finally, the samples were dried in the own for determination of the bulk density. The bulk density was correlated to parameters from the MIM-model and to the macropore volume to determine, whether bulk density can be used as a key parameter....

  6. AFM-porosimetry: density and pore volume measurements of particulate materials.

    Science.gov (United States)

    Sörensen, Malin H; Valle-Delgado, Juan J; Corkery, Robert W; Rutland, Mark W; Alberius, Peter C

    2008-06-01

    We introduced the novel technique of AFM-porosimetry and applied it to measure the total pore volume of porous particles with a spherical geometry. The methodology is based on using an atomic force microscope as a balance to measure masses of individual particles. Several particles within the same batch were measured, and by plotting particle mass versus particle volume, the bulk density of the sample can be extracted from the slope of the linear fit. The pore volume is then calculated from the densities of the bulk and matrix materials, respectively. In contrast to nitrogen sorption and mercury porosimetry, this method is capable of measuring the total pore volume regardless of pore size distribution and pore connectivity. In this study, three porous samples were investigated by AFM-porosimetry: one ordered mesoporous sample and two disordered foam structures. All samples were based on a matrix of amorphous silica templated by a block copolymer, Pluronic F127, swollen to various degrees with poly(propylene glycol). In addition, the density of silica spheres without a template was measured by two independent techniques: AFM and the Archimedes principle.

  7. Idealized Shale Sorption Isotherm Measurements to Determine Pore Volume, Pore Size Distribution, and Surface Area

    Science.gov (United States)

    Holmes, R.; Wang, B.; Aljama, H.; Rupp, E.; Wilcox, J.

    2014-12-01

    One method for mitigating the impacts of anthropogenic CO2-related climate change is the sequestration of CO2 in depleted gas and oil reservoirs, including shale. The accurate characterization of the heterogeneous material properties of shale, including pore volume, surface area, pore size distributions (PSDs) and composition is needed to understand the interaction of CO2 with shale. Idealized powdered shale sorption isotherms were created by varying incremental amounts of four essential components by weight. The first two components, organic carbon and clay, have been shown to be the most important components for CO2 uptake in shales. Organic carbon was represented by kerogen isolated from a Silurian shale, and clay groups were represented by illite from the Green River shale formation. The rest of the idealized shale was composed of equal parts by weight of SiO2 to represent quartz and CaCO3 to represent carbonate components. Baltic, Eagle Ford, and Barnett shale sorption measurements were used to validate the idealized samples. The idealized and validation shale sorption isotherms were measured volumetrically using low pressure N2 (77K) and CO2 (273K) adsorbates on a Quantachrome Autosorb IQ2. Gravimetric isotherms were also produced for a subset of these samples using CO2 and CH4adsorbates under subsurface temperature and pressure conditions using a Rubotherm magnetic suspension balance. Preliminary analyses were inconclusive in validating the idealized samples. This could be a result of conflicting reports of total organic carbon (TOC) content in each sample, a problem stemming from the heterogeneity of the samples and different techniques used for measuring TOC content. The TOC content of the validation samples (Eagle Ford and Barnett) was measured by Rock-Eval pyrolysis at Weatherford Laboratories, while the TOC content in the Baltic validation samples was determined by LECO TOC. Development of a uniform process for measuring TOC in the validation samples is

  8. Estimating pore and cement volumes in thin section

    Science.gov (United States)

    Halley, R.B.

    1978-01-01

    Point count estimates of pore, grain and cement volumes from thin sections are inaccurate, often by more than 100 percent, even though they may be surprisingly precise (reproducibility + or - 3 percent). Errors are produced by: 1) inclusion of submicroscopic pore space within solid volume and 2) edge effects caused by grain curvature within a 30-micron thick thin section. Submicroscopic porosity may be measured by various physical tests or may be visually estimated from scanning electron micrographs. Edge error takes the form of an envelope around grains and increases with decreasing grain size and sorting, increasing grain irregularity and tighter grain packing. Cements are greatly involved in edge error because of their position at grain peripheries and their generally small grain size. Edge error is minimized by methods which reduce the thickness of the sample viewed during point counting. Methods which effectively reduce thickness include use of ultra-thin thin sections or acetate peels, point counting in reflected light, or carefully focusing and counting on the upper surface of the thin section.

  9. Estimation of surface area and pore volume of activated carbons by methylene blue and iodine numbers

    Directory of Open Access Journals (Sweden)

    Cleiton A. Nunes

    2011-01-01

    Full Text Available Data of methylene blue number and iodine number of activated carbons samples were calibrated against the respective surface area, micropore volume and total pore volume using multiple regression. The models obtained from the calibrations were used in predicting these physical properties of a test group of activated carbon samples produced from several raw materials. In all cases, the predicted values were in good agreement with the expected values. The method allows extracting more information from the methylene blue and iodine adsorption studies than normally obtained with this type of material.

  10. Prediction of Shrinkage Pore Volume Fraction Using a Dimensionless Niyama Criterion

    Science.gov (United States)

    Carlson, Kent D.; Beckermann, Christoph

    2009-01-01

    A method is presented to use a dimensionless form of the well-known Niyama criterion to directly predict the amount of shrinkage porosity that forms during solidification of metal alloy castings. The main advancement offered by this method is that it avoids the need to know the threshold Niyama value below which shrinkage porosity forms; such threshold values are generally unknown and alloy dependent. The dimensionless criterion accounts for both the local thermal conditions (as in the original Niyama criterion) and the properties and solidification characteristics of the alloy. Once a dimensionless Niyama criterion value is obtained from casting simulation results, the corresponding shrinkage pore volume fraction can be determined knowing only the solid fraction-temperature curve and the total solidification shrinkage of the alloy. Curves providing the shrinkage pore volume percentage as a function of the dimensionless Niyama criterion are given for WCB steel, aluminum alloy A356, and magnesium alloy AZ91D. The present method is used in a general-purpose casting simulation software package to predict shrinkage porosity in three-dimensional (3-D) castings. Comparisons between simulated and experimental shrinkage porosity results for a WCB steel plate casting demonstrate that this method can reasonably predict shrinkage. Additional simulations for magnesium alloy AZ91D illustrate that this method is applicable to a wide variety of alloys and casting conditions.

  11. Characterization of the intragranular water regime within subsurface sediments: Pore volume, surface area, and mass transfer limitations

    Science.gov (United States)

    Hay, Michael B.; Stoliker, Deborah L.; Davis, James A.; Zachara, John M.

    2011-10-01

    Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ˜1% of the solid volume and intragranular surface areas of ˜20%-35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity.

  12. Characterization of the intragranular water regime within subsurface sediments: pore volume, surface area, and mass transfer limitations

    Science.gov (United States)

    Hay, Michael B.; Stoliker, Deborah L.; Davis, James A.; Zachara, John M.

    2011-01-01

    Although "intragranular" pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reactive surface area, and can thus strongly affect the transport of sorbing solutes. In this work, we demonstrate a batch experiment procedure using tritiated water as a high-resolution diffusive tracer to characterize the intragranular pore space. The method was tested using uranium-contaminated sediments from the vadose and capillary fringe zones beneath the former 300A process ponds at the Hanford site (Washington). Sediments were contacted with tracers in artificial groundwater, followed by a replacement of bulk solution with tracer-free groundwater and the monitoring of tracer release. From these data, intragranular pore volumes were calculated and mass transfer rates were quantified using a multirate first-order mass transfer model. Tritium-hydrogen exchange on surface hydroxyls was accounted for by conducting additional tracer experiments on sediment that was vacuum dried after reaction. The complementary ("wet" and "dry") techniques allowed for the simultaneous determination of intragranular porosity and surface area using tritium. The Hanford 300A samples exhibited intragranular pore volumes of ~1% of the solid volume and intragranular surface areas of ~20%–35% of the total surface area. Analogous experiments using bromide ion as a tracer yielded very different results, suggesting very little penetration of bromide into the intragranular porosity.

  13. Large pore volume mesoporous aluminum oxide synthesized via nano-assembly

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A new nano-assembly approach has been proposed for the preparation of macropore volume mesoporous aluminum oxide supports. Secondary nano-assembly and a frame structure mechanism for large pore volume mesoporous supports have been proposed. In a primary nano-assembly supersoluble micelle,aluminum hydroxide nanoparticles were precipitated in situ in surfactants with a volume balance (VB) less than 1,followed by secondary nano-assembly in linear and cylindrical shapes. The secondary nano-assembly of cylindrical aluminum hydroxides was calcined to form nano cylindrical aluminum oxides. For the formation of macropore volume mesoporous supports,we utilized a frame structure mechanism of mesoporous support,in which the exterior surface of the carrier may not be continuous. This macropore volume support has been used for the hydrotreatment of a residual oil catalyst,which possesses the following physical characteristics:pore volume 1.8―2.7 mL·g-1,specific surface area 180―429 m2·g-1,average pore diameter 17―57 nm,average pore diameter more than 10 nm (81%―94%),porosity 87%―93%,and crush strength 7.7―25 N·mm-1.

  14. Gas Breakthrough Pressure (GBP through Claystones: Correlation with FIB/SEM Imaging of the Pore Volume

    Directory of Open Access Journals (Sweden)

    Song Yang

    2016-07-01

    Full Text Available This contribution uses six claystone samples imaged by FIB/SEM (Focused Ion Beam/Scanning Electron Microscopy, within micrometric volumes located in the clay matrix; their 3D connected pore network is identified down to 17-22 nm pore size. All samples are gently dried to minimize damage, and several are impregnated with Poly(Methyl MethAcrylate (PMMA resin to avoid further damage during FIB/SEM observations. Three pore volumes out of six are connected between two parallel end surfaces through crack-like pores; two are not connected between any two parallel end surfaces; only one sample has a connected pore network distinct from cracks. By assuming varied pathways for gas to migrate by capillarity through the connected pore volumes (either by taking the shortest path, or through the largest path, or through the most frequent pore size, or by simulating the ingress of a non wetting fluid, we determine the Gas Breakthrough Pressure (GBP through the initially fully liquid saturated claystone, from these micrometric volumes. The scale change (from the micrometric to the macroscopic scale is assumed possible without changing the GBP value, and clay/water interactions are not accounted for. By comparison with GBP values measured in the laboratory on centimetric-sized claystone samples, it is concluded that breakthrough occurs most probably by capillary digitation; micro-cracks are the most probable pathways for gas, so that gas does not progress in a homogeneous manner through the claystone, as standard macroscopic finite element models would represent it. For intact claystone, predictions based on the capillary ingress of a non wetting fluid provide a GBP value ranging between 7-14 MPa.

  15. Simulation of pore pressure accumulation under cyclic loading using Finite Volume Method

    DEFF Research Database (Denmark)

    Tang, Tian; Hededal, Ole

    2014-01-01

    This paper presents a finite volume implementation of a porous, nonlinear soil model capable of simulating pore pressure accumulation under cyclic loading. The mathematical formulations are based on modified Biot’s coupled theory by substituting the original elastic constitutive model with an adv...... mapping algorithm is used to calculate the stress and strain relation in each control volume level. Test cases show very good performance of the model.......This paper presents a finite volume implementation of a porous, nonlinear soil model capable of simulating pore pressure accumulation under cyclic loading. The mathematical formulations are based on modified Biot’s coupled theory by substituting the original elastic constitutive model...... with an advanced elastoplastic model suitable for describing monotonic as well as cyclic loading conditions. The finite volume method is applied to discretize these formulations. The resulting set of coupled nonlinear algebraic equations are then solved by a ’segregated’ solution procedure. An efficient return...

  16. Low-cost preparation of mesoporous silica with high pore volume

    Institute of Scientific and Technical Information of China (English)

    Shuling Shen; Wei Wu; Kai Guo; Jianfeng Chen

    2007-01-01

    Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol (PEG). The obtained materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermo gravimetric analyzer and differential scanning calorimetry (TG-DSC), nitrogen adsorption-desorption measurements, and X-ray diffraction (XRD). The results showed that the changes of the pore parameters depended on both the surfactant content and heat treatment temperature. When the content of PEG was 10wt% and the obtained PEG/SiO2 composite was heated at 600℃, the mesoporous silica with a pore volume of 2.2 cm3/g, a BET specific surface area of 361.55 m2/g, and a diameter of 2-4 μm could be obtained. The obtained mesoporous silica materials have potential applications in the fields of paint and plastic, as thickening, reinforcing, and flatting agents.

  17. Surface area and volume fraction of random open-pore systems

    Science.gov (United States)

    Hermann, H.; Elsner, A.; Stoyan, D.

    2013-12-01

    For the first time, explicit approximate formulas are presented for the volume fraction and specific surface area of random open-pore systems with poly-disperse pore size distributions. It is shown that the formulas are valid for broad classes of models for porous media characterized by tunable pore size distributions and a variable degree of inter-penetrability of pores. The formulas for the poly-disperse case are based on expressions derived previously for mono-disperse penetrable-sphere models. The results are obtained by analysis of a series of open-pore models, which are prepared by computer simulation of systems of randomly packed partially penetrable spheres with various poly-disperse size distributions such as gamma, lognormal, and Gaussian. The formulas are applied in a study of atomic layer deposition processes on open-pore systems, and the effective Young's modulus and the effective thermal conductivity of Al2O3 coated porous polypropylene electrodes for lithium ion batteries are predicted.

  18. The effects of firing numbers on the opening total pore volume, translucency parameter and color of dental all-ceramic systems%烧结次数对牙科全瓷开放性总孔体积、透明度和色度的影响

    Institute of Scientific and Technical Information of China (English)

    李水根; 庞莉苹; 姚江武

    2012-01-01

    目的 评价烧结次数对牙科全瓷开放性总孔体积(TPV)、透明度(TP)和色度的影响.方法 采用热压全瓷(IPS Empress Ⅱ)、氧化铝全瓷(In-Cream alumina blanks)和氧化锆全瓷(Cercon CAD/CAM zirconia)3种材料制作试样,使用分光光谱仪与表面积和孔隙率仪测量计算试样经过1、3、5次烧结后的TP、明度(ΔL)、彩度(ΔC)和TPV变化.应用SAS 8.0软件对数据进行统计分析.结果 相同烧结次数下,3种全瓷试件的TPV、TP、ΔL和ΔC间均存在统计学差异(P<0.05),其中TPV为热压全瓷大于氧化铝全瓷和氧化锆全瓷(P<0.05);TP和ΔL均为热压全瓷最高,氧化锆全瓷其次,氧化铝全瓷最低(P<0.05);ΔC为热压全瓷和氧化铝全瓷大于氧化锆全瓷(P<0.05).不同烧结次数下,同一全瓷试件TPV、TP、ΔL和ΔC间也存在统计学差异(P<0.05).随着烧结次数的增加,TPV逐渐减小,TP、ΔL和△C逐渐增加.烧结次数与TPV、TPV与TP和ΔL均呈负相关(P<0.05).结论 重复烧结可通过TPV变化影响全瓷修复体的TP和ΔL的稳定性.%Objective To evaluate the effects of firing numbers on the total opening pore volume (TPV), translucency parameter (TP) and color of dental all-ceramic systems. Methods Specimens of three kinds of all-ceramics systems were made, i.e. heat pressed all-ceramic (IPS Empress E), alumina all-ceramic (In-Cream alumina blanks) and zirconia all-ceramic (Cercon CAD/CAM zirconia). The specimens' TP, lightness (AL), chroma (AC) and TPY after 1, 3 and 5 firings were measured and calculated by spectrophotometer and surface area/porosity system. The data were analyzed statistically using SAS 8.0 software. Results There were significant differences in TPV, TP, AL and AC for all-ceramic specimens at same number of firings (Palumina and zirconia for TPV(Pzirconia>alumina for TP and AL(Pzirconia for AC(P<0.05). The significant differences also presented in TPV, TP, AL and AC for a same specimen at different

  19. Petrophysical studies of north American carbonate rock samples and evaluation of pore-volume compressibility models

    Science.gov (United States)

    da Silva, Gilberto Peixoto; Franco, Daniel R.; Stael, Giovanni C.; da Costa de Oliveira Lima, Maira; Sant'Anna Martins, Ricardo; de Moraes França, Olívia; Azeredo, Rodrigo B. V.

    2015-12-01

    In this work, we evaluate two pore volume compressibility models that are currently discussed in the literature (Horne, 1990; Jalalh, 2006b). Five groups of carbonate rock samples from the three following sedimentary basins in North America that are known for their association with hydrocarbon deposits were selected for this study: (i) the Guelph Formation of the Michigan Basin (Middle Silurian); (ii) the Edwards Formation of the Central Texas Platform (Middle Cretaceous); and (iii) the Burlington-Keokuk Formation of the Mississippian System (Lower Mississippian). In addition to the evaluation of the compressibility model, a petrophysical evaluation of these rock samples was conducted. Additional characterizations, such as grain density, the effective porosity, absolute grain permeability, thin section petrography, MICP and NMR, were performed to complement constant pore-pressure compressibility tests. Although both models presented an overall good representation of the compressibility behavior of the studied carbonate rocks, even when considering their broad porosity range (~ 2-38%), the model proposed by Jalalh (2006b) performed better with a confidence level of 95% and a prediction interval of 68%.

  20. Reduction of total lung capacity in obese men: comparison of total intrathoracic and gas volumes.

    Science.gov (United States)

    Watson, R A; Pride, N B; Thomas, E Louise; Fitzpatrick, J; Durighel, G; McCarthy, J; Morin, S X; Ind, P W; Bell, J D

    2010-06-01

    Restriction of total lung capacity (TLC) is found in some obese subjects, but the mechanism is unclear. Two hypotheses are as follows: 1) increased abdominal volume prevents full descent of the diaphragm; and 2) increased intrathoracic fat reduces space for full lung expansion. We have measured total intrathoracic volume at full inflation using magnetic resonance imaging (MRI) in 14 asymptomatic obese men [mean age 52 yr, body mass index (BMI) 35-45 kg/m2] and 7 control men (mean age 50 yr, BMI 22-27 kg/m2). MRI volumes were compared with gas volumes at TLC. All measurements were made with subjects supine. Obese men had smaller functional residual capacity (FRC) and FRC-to-TLC ratio than control men. There was a 12% predicted difference in mean TLC between obese (84% predicted) and control men (96% predicted). In contrast, differences in total intrathoracic volume (MRI) at full inflation were only 4% predicted TLC (obese 116% predicted TLC, control 120% predicted TLC), because mediastinal volume was larger in obese than in control [heart and major vessels (obese 1.10 liter, control 0.87 liter, P=0.016) and intrathoracic fat (obese 0.68 liter, control 0.23 liter, P80% predicted (ON) was 26% predicted TLC. Mediastinal volume was similar in OR (1.84 liter) and ON (1.73 liter), but total intrathoracic volume was 19% predicted TLC smaller in OR than in ON. We conclude that the major factor restricting TLC in some obese men was reduced thoracic expansion at full inflation.

  1. Two catesories of fractal models of rock and soil expressing volume and size-distribution of pores and grains

    Institute of Scientific and Technical Information of China (English)

    TAO GaoLiang; ZHANG JiRu

    2009-01-01

    Based on the Sierpinski carpet and Menger sponge models, two categories of fractal models of rock and soil which are composed of the volume fractal model of pores, the volume fractal model of grains, pore-size or particle-size distribution fractal models are established and their relations are clarified in this paper. Through comparison and analysis, it is found that previous models can be unified by the two categories of fractal models, so the unified fractal models are formed. Experimental results presented by Katz indicate that the first category of fractal models can be used to express the fractal behavior of sandstone. A scanning electron microscope (SEM) will be used to study the microstructure of soft clay and it will be testified that the fractal behavior of soft clay suits the second category of fractal models.

  2. Preparation of High Surface Area, Large Pore Volume Alumina by Using β-Cyclodextrin as a Non-surfactant Template

    Institute of Scientific and Technical Information of China (English)

    Lai Jun WANG; Ming Fen WEN; Yu Shan LI; Dong YANG; Jing CHEN; Chong Li SONG

    2006-01-01

    A series of alumina samples were prepared using β-cyclodextrin as the non-surfactant template. These samples were characterized by XRD, BET and TEM. The results showed that the alumina samples prepared using β-cyclodextrin template had the higher surface areas (124-484 m2/g), larger pore volumes (0.7-1.27 mL/g) and more thermal stability than samples prepared without using β-cyclodextrin.

  3. Pore-scale simulations of drainage in granular materials: Finite size effects and the representative elementary volume

    Science.gov (United States)

    Yuan, Chao; Chareyre, Bruno; Darve, Félix

    2016-09-01

    A pore-scale model is introduced for two-phase flow in dense packings of polydisperse spheres. The model is developed as a component of a more general hydromechanical coupling framework based on the discrete element method, which will be elaborated in future papers and will apply to various processes of interest in soil science, in geomechanics and in oil and gas production. Here the emphasis is on the generation of a network of pores mapping the void space between spherical grains, and the definition of local criteria governing the primary drainage process. The pore space is decomposed by Regular Triangulation, from which a set of pores connected by throats are identified. A local entry capillary pressure is evaluated for each throat, based on the balance of capillary pressure and surface tension at equilibrium. The model reflects the possible entrapment of disconnected patches of the receding wetting phase. It is validated by a comparison with drainage experiments. In the last part of the paper, a series of simulations are reported to illustrate size and boundary effects, key questions when studying small samples made of spherical particles be it in simulations or experiments. Repeated tests on samples of different sizes give evolution of water content which are not only scattered but also strongly biased for small sample sizes. More than 20,000 spheres are needed to reduce the bias on saturation below 0.02. Additional statistics are generated by subsampling a large sample of 64,000 spheres. They suggest that the minimal sampling volume for evaluating saturation is one hundred times greater that the sampling volume needed for measuring porosity with the same accuracy. This requirement in terms of sample size induces a need for efficient computer codes. The method described herein has a low algorithmic complexity in order to satisfy this requirement. It will be well suited to further developments toward coupled flow-deformation problems in which evolution of the

  4. Quantifying Water Stress Using Total Water Volumes and GRACE

    Science.gov (United States)

    Richey, A. S.; Famiglietti, J. S.; Druffel-Rodriguez, R.

    2011-12-01

    Water will follow oil as the next critical resource leading to unrest and uprisings globally. To better manage this threat, an improved understanding of the distribution of water stress is required today. This study builds upon previous efforts to characterize water stress by improving both the quantification of human water use and the definition of water availability. Current statistics on human water use are often outdated or inaccurately reported nationally, especially for groundwater. This study improves these estimates by defining human water use in two ways. First, we use NASA's Gravity Recovery and Climate Experiment (GRACE) to isolate the anthropogenic signal in water storage anomalies, which we equate to water use. Second, we quantify an ideal water demand by using average water requirements for the domestic, industrial, and agricultural water use sectors. Water availability has traditionally been limited to "renewable" water, which ignores large, stored water sources that humans use. We compare water stress estimates derived using either renewable water or the total volume of water globally. We use the best-available data to quantify total aquifer and surface water volumes, as compared to groundwater recharge and surface water runoff from land-surface models. The work presented here should provide a more realistic image of water stress by explicitly quantifying groundwater, defining water availability as total water supply, and using GRACE to more accurately quantify water use.

  5. Total Dose Hardness Assurance. Volume I. Identification of Techniques.

    Science.gov (United States)

    1980-02-01

    under Contract F29601-78-C-0022. The project officer for the Air Force was Mr. Roe J. Maier. The program manager and principal investigator for BDM was...Assurance Techniques," AFWL-TR-73-134, 3 Volumes, January 1974. 44. Bruncke, W. C. et al. " Tecniques for Screening Bipolar Transistor Degradation Due to

  6. Mesoporous calcium-silicon xerogels with mesopore size and pore volume influence hMSC behaviors by load and sustained release of rhBMP-2.

    Science.gov (United States)

    Song, Wenhua; Li, Xiangde; Qian, Jun; Lv, Guoyu; Yan, Yonggang; Su, Jiacan; Wei, Jie

    2015-01-01

    Mesoporous calcium-silicon xerogels with a pore size of 15 nm (MCS-15) and pore volume of 1.43 cm(3)/g were synthesized by using 1,3,5-mesitylene (TMB) as the pore-expanding agent. The MCS-15 exhibited good degradability with the weight loss of 50 wt% after soaking in Tris-HCl solution for 56 days, which was higher than the 30 wt% loss shown by mesoporous calcium-silicon xerogels with a pore size of 4 nm (MCS-4). The pore size and pore volume of MCS-15 had significant influences on load and release of recombinant human bone morphogenetic protein-2 (rhBMP-2). The MCS-15 had a higher capacity to encapsulate a large amount of rhBMP-2; it could adsorb 45 mg/g of rhBMP-2 in phosphate-buffered saline after 24 hours, which was more than twice that with MCS-4 (20 mg/g). Moreover, the MCS-15 system exhibited sustained release of rhBMP-2 as compared with MCS-4 system (showing a burst release). The MCS-15/rhBMP-2 system could promote the proliferation and differentiation of human mesenchymal stem cells, showing good cytocompatibility and bioactivity. The results indicated that MCS-15, with larger mesopore size and higher pore volume, might be a promising carrier for loading and sustained release of rhBMP-2, which could be used as bone repair material with built-in osteoinduction function in bone reconstruction.

  7. Effects of pore-scale dispersion, degree of heterogeneity, sampling size, and source volume on the concentration moments of conservative solutes in heterogeneous formations

    Science.gov (United States)

    Daniele Tonina; Alberto Bellin

    2008-01-01

    Pore-scale dispersion (PSD), aquifer heterogeneity, sampling volume, and source size influence solute concentrations of conservative tracers transported in heterogeneous porous formations. In this work, we developed a new set of analytical solutions for the concentration ensemble mean, variance, and coefficient of variation (CV), which consider the effects of all these...

  8. Mesoporous calcium–silicon xerogels with mesopore size and pore volume influence hMSC behaviors by load and sustained release of rhBMP-2

    Directory of Open Access Journals (Sweden)

    Song W

    2015-03-01

    Full Text Available Wenhua Song,1,* Xiangde Li,1,* Jun Qian,1 Guoyu Lv,2 Yonggang Yan,2 Jiacan Su,3 Jie Wei1 1Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai, People’s Republic of China; 2College of Physical Science and Technology, Sichuan University, Chengdu, People’s Republic of China; 3Changhai Hospital, Second Military Medical University, Shanghai, People’s Republic of China *These authors contributed equally to this paper Abstract: Mesoporous calcium–silicon xerogels with a pore size of 15 nm (MCS-15 and pore volume of 1.43 cm3/g were synthesized by using 1,3,5-mesitylene (TMB as the pore-expanding agent. The MCS-15 exhibited good degradability with the weight loss of 50 wt% after soaking in Tris-HCl solution for 56 days, which was higher than the 30 wt% loss shown by mesoporous calcium–silicon xerogels with a pore size of 4 nm (MCS-4. The pore size and pore volume of MCS-15 had significant influences on load and release of recombinant human bone morphogenetic protein-2 (rhBMP-2. The MCS-15 had a higher capacity to encapsulate a large amount of rhBMP-2; it could adsorb 45 mg/g of rhBMP-2 in phosphate-buffered saline after 24 hours, which was more than twice that with MCS-4 (20 mg/g. Moreover, the MCS-15 system exhibited sustained release of rhBMP-2 as compared with MCS-4 system (showing a burst release. The MCS-15/rhBMP-2 system could promote the proliferation and differentiation of human mesenchymal stem cells, showing good cytocompatibility and bioactivity. The results indicated that MCS-15, with larger mesopore size and higher pore volume, might be a promising carrier for loading and sustained release of rhBMP-2, which could be used as bone repair material with built-in osteoinduction function in bone reconstruction. Keywords: mesoporous calcium–silicon xerogels, pore size, pore volume, load-release, rhBMP-2

  9. Total Quality Management Guide. Volume 2. A Guide to Implementation

    Science.gov (United States)

    1990-02-15

    Feigenbaum, Armand V. Total Quality Control. New York: McGraw-Hill Book Company. 1983. bnai, Masaaki. Kaizen . New York: Random House. 1986. Ishikawa...Yasuhiro. Toyota Production System. Institute of Industrial Engineers. Norcross, Ga. 1982. Ouchi, William G. Theory Z. Reading, Mass.: Addison-Wesley

  10. Relation between trunk fat volume and reduction of total lung capacity in obese men.

    Science.gov (United States)

    Watson, R A; Pride, N B; Thomas, E Louise; Ind, P W; Bell, J D

    2012-01-01

    Reduction in total lung capacity (TLC) in obese men is associated with restricted expansion of the thoracic cavity at full inflation. We hypothesized that thoracic expansion was reduced by the load imposed by increased total trunk fat volume or its distribution. Using MRI, we measured internal and subcutaneous trunk fat and total abdominal and thoracic volumes at full inflation in 14 obese men [mean age: 52.4 yr, body mass index (BMI): 38.8 (range: 36-44) kg/m(2)] and 7 control men [mean age: 50.1 yr, BMI: 25.0 (range: 22-27.5) kg/m(2)]. TLC was measured by multibreath helium dilution and was restricted (fat volume was 16.65 (range: 12.6-21.8) liters in obese men and 6.98 (range: 3.0-10.8) liters in control men. Anthropometry and mean total trunk fat volumes were similar in OR men and obese men without restriction (the ON subgroup). Mean total intraabdominal volume was 9.41 liters in OR men and 11.15 liters in ON men. In obese men, reduced thoracic expansion at full inflation and restriction of TLC were not inversely related to a large volume of 1) intra-abdominal or total abdominal fat, 2) subcutaneous fat volume around the thorax, or 3) total trunk fat volume. In addition, trunk fat volumes in obese men were not inversely related to gas volume or estimated intrathoracic volume at supine functional residual capacity. In conclusion, this study failed to support the hypotheses that restriction of TLC or impaired expansion of the thorax at full inflation in middle-aged obese men was simply a consequence of a large abdominal volume or total trunk fat volume or its distribution.

  11. Sulphonic acid derivatives as probes of pore properties of volume-regulated anion channels in endothelial cells.

    Science.gov (United States)

    Droogmans, G; Maertens, C; Prenen, J; Nilius, B

    1999-09-01

    1. We have used the whole-cell patch-clamp technique to study the effects of 4-sulphonic-calixarenes and some other poly-sulphonic acid agents, such as suramin and basilen blue, on volume-regulated anion channel (VRAC) currents in cultured endothelial cells (CPAE cells). 2. The 4-sulphonic-calixarenes induced a fast inhibition at positive potentials but were ineffective at negative potentials. At small positive potentials, 4-sulphonic-calix[4]arene was a more effective inhibitor than 4-sulphonic-calix[6]arene and -calix[8]arene, which became more effective at more positive potentials. 3. Also suramin and basilen blue induced a voltage dependent current inhibition, reaching a maximum around +40 mV and declining at more positive potentials. 4. The voltage dependence of inhibition was modelled by assuming that these negatively charged molecules bind to a site inside VRAC that senses a fraction delta of the applied electrical field, ranging beween 0.16 to 0.32. 4-Sulphonic-calix[4]arene, suramin and basilen blue bind and occlude VRAC at moderate potentials, but permeate the channel at more positive potentials. 4-Sulphonic-calix[6]arene and -calix[8]arene however do not permeate the channel. From the structural information of the calixarenes, we estimate a lower and upper limit of 11*12 and 17*12 A2 respectively for the cross-sectional area of the pore.

  12. COMPARISON BETWEEN MULTICOPTER UAV AND TOTAL STATION FOR ESTIMATING STOCKPILE VOLUMES

    Directory of Open Access Journals (Sweden)

    C. Arango

    2015-08-01

    Full Text Available Currently the UAV (Unmanned Aerial Vehicle have become an alternative for different engineering applications, especially in surveying, one of these applications is the calculation of volumes of stockpiled material, but there are questions about its accuracy and efficiency, the purpose of this article is to compare traditional surveying methods for estimating total volumes through data obtained by total stations and data obtained by a multicopter UAV. In order to answer these questions we obtain data from the same location and the results were compared. After comparing the results it was found that there was a 2,88% difference between the volume calculated with the total station data and the actual volume, and −0,67% difference between the volume calculated with the UAV data and the actual volume, concluding that the estimated volume with UAV data is more accurate.

  13. Synthesis of Macro-Mesostructuredγ-Al2O3 with Large Pore Volume and High Surface Area by a Facile Secondary Reforming Method

    Institute of Scientific and Technical Information of China (English)

    Meng Xiuhong; Duan Linhai; Xie Xiaohua; Wang Qiang; Wang Haiyan

    2014-01-01

    Through improving the aging process during synthesis of the support,γ-Al2O3 with large pore volume and high surface area was synthesized by a facile secondary reforming method. The synthesis parameters, such as the reaction tem-perature, the ifrst aging temperature and the second aging temperature, were investigated. The textural properties ofγ-Al2O3 were characterized by means of N2 adsorption-desorption isotherms, X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetry (TG). The experimental results indicated that AACH and amorphous AlOOH were the precursors of alumina, which were formed via precipitation from solutions after reaction of aluminum sulphate with ammonium hydrogen carbonate. The precursor nanocrystallites grew and re-assembled during the secondary reforming process, which resulted in an increased pore size and pore volume and a decreased bulk density. The as-synthesizedγ-Al2O3 materials featured meso/macroporosity, large pore volume (2.175 cm3/g), high surface area (237.8 m2/g), and low bulk density (0.284 g/mL).

  14. A coupled soil-pore fluid formulation for modeling soil liquefaction and cyclic mobility in seabed using the finite volume method

    DEFF Research Database (Denmark)

    Tang, Tian; Roenby, Johan; Hededal, Ole

    by formulating the strong interactions between soil skeleton and the pore fluid via a coupled set of partial differential equations. A single bounding surface soil model capable of simulating the accumulations of pore pressures, strains, dilatancy, and strain „softening‟, is then adopted for quantifying...... the cyclic soil constitutive relations. To deal with the high non-linearity in the equations, the finite volume (FV) method is proposed for the numerical simulation. The corresponding discretization strategies and solution algorithms, including the conventional segregated method and the more recent block...

  15. Pore Structure of Cement Pastes Blended with Volcanic Rock

    Institute of Scientific and Technical Information of China (English)

    YU Lehua; ZHOU Shuangxi; LI Liling

    2016-01-01

    The pore parameters of cement pastes blended with volcanic rock at the curing age of 1, 28 and 90 d were de-termined by a mercury intrusion porosimetry. The pore structure of the pastes was characterized through the analysis of porosity, average pore diameter, the most probable pore aperture, pore size distribution, as well as total pore volume. For the improvement of mechanical property and durability of cement-based material, the correlation of the formed pore structure with hydration time and replacement level of volcanic rock for cement was revealed. The results indicate that volcanic rock can diminish porosity and reduce pore size in cement paste when curing time prolongs, which is particu-larly prominent with replacement level of less than 20% in late period. The more harmful pores (i.e., capillary pore) are gradually transformed into harmless pore (i.e., gel pores or micropore), even fully filled and disappeared when hydration products increase. The pore structure of the cement paste is thus refined. The beneficial effect of volcanic rock on the pore structure of cement paste could enhance the mechanical property and durability of cement-based material.

  16. Meaningful Thresholds for the Volume-Outcome Relationship in Total Knee Arthroplasty.

    Science.gov (United States)

    Wilson, Sean; Marx, Robert G; Pan, Ting-Jung; Lyman, Stephen

    2016-10-19

    Increasing evidence supports the finding that patients undergoing a total knee arthroplasty with high-volume physicians and hospitals achieve better outcomes. Unfortunately, the existing definitions for high-volume surgeons and hospitals are highly variable and entirely arbitrary. The aim of this study was to identify a set of meaningful hospital and surgeon total knee arthroplasty volume thresholds. Using 289,976 patients undergoing primary total knee arthroplasty from an administrative database, we applied stratum-specific likelihood ratio (SSLR) analysis of a receiver operating characteristic (ROC) curve to generate sets of volume thresholds most predictive of adverse outcomes. The outcomes considered for surgeon volume included 90-day complication and 2-year revision. For hospital volume, we considered 90-day complications and 90-day mortality. SSLR analysis of the ROC curves for 90-day complication and 2-year revision rates by surgeon volume identified four volume categories: 0 to 12, 13 to 59, 60 to 145, and ≥146 total knee arthroplasties per year. Complication rates decreased significantly (p < 0.05) in progressively higher-volume categories. Revision rates followed a similar pattern, but did not decrease between surgeons performing 60 to 145 arthroplasties per year and those performing ≥146 arthroplasties per year. SSLR analysis of 90-day complication and 90-day mortality rates by hospital volume also identified four volume categories: 0 to 89, 90 to 235, 236 to 644, and ≥645 total knee arthroplasties per year. Complication rates decreased significantly (p < 0.05) in progressively higher-volume categories, but the rates did not decrease between hospitals performing 236 to 644 arthroplasties per year and those performing ≥645 arthroplasties per year. Mortality rates for hospitals with ≥645 total knee arthroplasties per year were significantly lower (p < 0.05) than those below the threshold. Our study supports the use of SSLR analysis of ROC curves

  17. Water-soluble gases as partitioning tracers to investigate the pore volume?transmissivity correlation in a fracture

    Science.gov (United States)

    Lunati, Ivan; Kinzelbach, Wolfgang

    2004-11-01

    Hydraulically equivalent fractures may show striking differences when a gas-migration experiment is performed because of the different correlations between transmissivity, pore volume and entry pressure. We numerically simulate gas migration between injection and extraction boreholes in a parallel plate fracture with a heterogeneous fault gouge, in a rough-walled fracture filled with homogeneous material, and in a rough-walled empty fracture. The parallel plate model and the empty model clearly show the existence of preferential paths; for high variance of the transmissivity field, gas flow takes place only in few discrete channels separated by water-saturated regions. In contrast, in the fracture filled with homogeneous fault gouge, the gas saturation is continuous and more uniformly distributed. It appears a fundamental issue to be able to discriminate in situ among conceptual models that can yield such a different gas-saturation distribution. As in practice, the saturation distribution cannot be directly observed, tracer experiments are performed to characterize a fracture. For these reasons, we simulate the transport of tracers, which are added to the gas phase as soon as quasi-steady saturation distribution and extraction rate are achieved, and we compare the breakthrough curves obtained assuming different models. Our numerical simulations suggest that discrimination among the models on the basis of single-tracer tests is unlikely. A better tool to investigate fracture properties is provided by a gas-tracer test, in which a cocktail of gases with different water solubility is employed. These gases behave as partitioning tracers and allow us to estimate the gas saturation in the fracture. Indeed, by comparison of the residence-time distributions of different gases, we are able to compute a streamline effective saturation, which is an excellent estimate of fracture saturation. In addition, the streamline effective saturation curve contains information that is

  18. China’s Total Bauxite Resource Volume has Topped 4 Billion Tonnes

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>According to data published in the "Communiqué on Land and Resources of China for 2012" by The Ministry of Land and Resources, in the whole year of 2012, the volume of newly added identified bauxite resource amounted to 210 million tonnes, at the end of 2012 the total volume of domestic identified bauxite resource

  19. Total blood volume in the normally performing Standardbred trotter: age and sex variations.

    Science.gov (United States)

    Persson, S G; Funkquist, P; Nyman, G

    1996-03-01

    The purposes of this study were to elucidate the influences of age and sex on the mass specific blood volume parameters: total blood volume (TBV/BW, ml/kg), plasma volume (PV/ BW, ml/kg), total red cell volume (CV/BW, ml/kg) and maximal packed cell volume (PCV, l/l, i.e. after total mobilisation of the splenic red cell reservoir) and to establish reference values for these in normally performing Standardbred trotting race horses. In total 205 horses were studied. They were all, according to their owners and/or trainers, performing satisfactorily in racing or training for shortly impending racing. Blood volume determination was done with the Evans blue dye dilution technique after exercise induced emptying of the spleen. Both age and sex were found to influence variation of these parameters significantly, with the possible exception of PV/BW, whereas the primary variation appeared to be in CV/BW. It was concluded that taking age and sex dependent variations into consideration will render prediction of normal values for the blood volume parameters in the athletic Standardbred trotter more reliable and the detection of abnormal deviations more precise if five age and sex groups are used for comparisons.

  20. The Effect of Structured Exercise Intervention on Intensity and Volume of Total Physical Activity

    Directory of Open Access Journals (Sweden)

    Niko Wasenius

    2014-12-01

    Full Text Available This study aimed to investigate the effects of a 12-week structured exercise intervention on total physical activity and its subcategories. Twenty-three overweight or obese middle aged men with impaired glucose regulation were randomized into a 12-week Nordic walking group, a power-type resistance training group, and a non-exercise control group. Physical activity was measured with questionnaires before the intervention (1–4 weeks and during the intervention (1–12 weeks and was expressed in metabolic equivalents of task. No significant change in the volume of total physical activity between or within the groups was observed (p > 0.050. The volume of total leisure-time physical activity (structured exercises + non-structured leisure-time physical activity increased significantly in the Nordic walking group (p 0.050 compared to the control group. In both exercise groups increase in the weekly volume of total leisure-time physical activity was inversely associated with the volume of non-leisure-time physical activities. In conclusion, structured exercise intervention did not increase the volume of total physical activity. Albeit, endurance training can increase the volume of high intensity physical activities, however it is associated with compensatory decrease in lower intensity physical activities. To achieve effective personalized exercise program, individuality in compensatory behavior should be recognised.

  1. A coupled soil-pore fluid formulation for modeling soil liquefaction and cyclic mobility in seabed using the finite volume method

    DEFF Research Database (Denmark)

    Tang, Tian; Roenby, Johan; Hededal, Ole

    by formulating the strong interactions between soil skeleton and the pore fluid via a coupled set of partial differential equations. A single bounding surface soil model capable of simulating the accumulations of pore pressures, strains, dilatancy, and strain „softening‟, is then adopted for quantifying...... the cyclic soil constitutive relations. To deal with the high non-linearity in the equations, the finite volume (FV) method is proposed for the numerical simulation. The corresponding discretization strategies and solution algorithms, including the conventional segregated method and the more recent block...... matrix solver, are discussed as well. Overall, investigations in this paper provide a methodology for developing a numerical code simulating liquefaction and cyclic mobility. In future work this will be implemented in practice with the aid of the open source CFD toolbox, OpenFOAM....

  2. Total-dose radiation effects data for semiconductor devices, volume 3

    Science.gov (United States)

    Price, W. E.; Martin, K. E.; Nichols, D. K.; Gauthier, M. K.; Brown, S. F.

    1982-09-01

    Volume 3 of this three-volume set provides a detailed analysis of the data in Volumes 1 and 2, most of which was generated for the Galileo Orbiter Program in support of NASA space programs. Volume 1 includes total ionizing dose radiation test data on diodes, bipolar transistors, field effect transistors, and miscellaneous discrete solid-state devices. Volume 2 includes similar data on integrated circuits and a few large-scale integrated circuits. The data of Volumes 1 and 2 are combined in graphic format in Volume 3 to provide a comparison of radiation sensitivities of devices of a given type and different manufacturer, a comparison of multiple tests for a single data code, a comparison of multiple tests for a single lot, and a comparison of radiation sensitivities vs time (date codes). All data were generated using a steady-state 2.5-MeV electron source (Dynamitron) or a Cobalt-60 gamma ray source. The data that compose Volume 3 represent 26 different device types, 224 tests, and a total of 1040 devices. A comparison of the effects of steady-state electrons and Cobat-60 gamma rays is also presented.

  3. Developmentally Sensitive Interaction Effects of Genes and the Social Environment on Total and Subcortical Brain Volumes.

    Directory of Open Access Journals (Sweden)

    Jennifer S Richards

    Full Text Available Smaller total brain and subcortical volumes have been linked to psychopathology including attention-deficit/hyperactivity disorder (ADHD. Identifying mechanisms underlying these alterations, therefore, is of great importance. We investigated the role of gene-environment interactions (GxE in interindividual variability of total gray matter (GM, caudate, and putamen volumes. Brain volumes were derived from structural magnetic resonance imaging scans in participants with (N = 312 and without ADHD (N = 437 from N = 402 families (age M = 17.00, SD = 3.60. GxE effects between DAT1, 5-HTT, and DRD4 and social environments (maternal expressed warmth and criticism; positive and deviant peer affiliation as well as the possible moderating effect of age were examined using linear mixed modeling. We also tested whether findings depended on ADHD severity. Deviant peer affiliation was associated with lower caudate volume. Participants with low deviant peer affiliations had larger total GM volumes with increasing age. Likewise, developmentally sensitive GxE effects were found on total GM and putamen volume. For total GM, differential age effects were found for DAT1 9-repeat and HTTLPR L/L genotypes, depending on the amount of positive peer affiliation. For putamen volume, DRD4 7-repeat carriers and DAT1 10/10 homozygotes showed opposite age relations depending on positive peer affiliation and maternal criticism, respectively. All results were independent of ADHD severity. The presence of differential age-dependent GxE effects might explain the diverse and sometimes opposing results of environmental and genetic effects on brain volumes observed so far.

  4. Forecasting on the total volumes of Malaysia's imports and exports by multiple linear regression

    Science.gov (United States)

    Beh, W. L.; Yong, M. K. Au

    2017-04-01

    This study is to give an insight on the doubt of the important of macroeconomic variables that affecting the total volumes of Malaysia's imports and exports by using multiple linear regression (MLR) analysis. The time frame for this study will be determined by using quarterly data of the total volumes of Malaysia's imports and exports covering the period between 2000-2015. The macroeconomic variables will be limited to eleven variables which are the exchange rate of US Dollar with Malaysia Ringgit (USD-MYR), exchange rate of China Yuan with Malaysia Ringgit (RMB-MYR), exchange rate of European Euro with Malaysia Ringgit (EUR-MYR), exchange rate of Singapore Dollar with Malaysia Ringgit (SGD-MYR), crude oil prices, gold prices, producer price index (PPI), interest rate, consumer price index (CPI), industrial production index (IPI) and gross domestic product (GDP). This study has applied the Johansen Co-integration test to investigate the relationship among the total volumes to Malaysia's imports and exports. The result shows that crude oil prices, RMB-MYR, EUR-MYR and IPI play important roles in the total volumes of Malaysia's imports. Meanwhile crude oil price, USD-MYR and GDP play important roles in the total volumes of Malaysia's exports.

  5. Nanometer-Scale Pore Characteristics of Lacustrine Shale, Songliao Basin, NE China.

    Directory of Open Access Journals (Sweden)

    Min Wang

    Full Text Available In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale pores or fractures, so the pore types and PSDs (pore size distributions play a major role in the shale oil occurrence (free or absorbed state, amount of oil, and flow features. The pore types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale pores and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope observations, low pressure CO2 and N2 adsorption, and high-pressure mercury injection experiments. Analysis results indicate that: (1 Pore types in the lacustrine shale include inter-matrix pores, intergranular pores, organic matter pores, and dissolution pores, and these pores are dominated by mesopores and micropores; (2 There is no apparent correlation between pore volumes and clay content, however, a weak negative correlation is present between total pore volume and carbonate content; (3 Pores in lacustrine shale are well developed when the organic matter maturity (Ro is >1.0% and the pore volume is positively correlated with the TOC (total organic carbon content. The statistical results suggest that oil in lacustrine shale mainly occurs in pores with diameters larger than 40 nm. However, more research is needed to determine whether this minimum pore diameter for oil occurrence in lacustrine shale is widely applicable.

  6. Effects of respiratory rate and tidal volume on gas exchange in total liquid ventilation.

    Science.gov (United States)

    Bull, Joseph L; Tredici, Stefano; Fujioka, Hideki; Komori, Eisaku; Grotberg, James B; Hirschl, Ronald B

    2009-01-01

    Using a rabbit model of total liquid ventilation (TLV), and in a corresponding theoretical model, we compared nine tidal volume-respiratory rate combinations to identify a ventilator strategy to maximize gas exchange, while avoiding choked flow, during TLV. Nine different ventilation strategies were tested in each animal (n = 12): low [LR = 2.5 breath/min (bpm)], medium (MR = 5 bpm), or high (HR = 7.5 bpm) respiratory rates were combined with a low (LV = 10 ml/kg), medium (MV = 15 ml/kg), or high (HV = 20 ml/kg) tidal volumes. Blood gases and partial pressures, perfluorocarbon gas content, and airway pressures were measured for each combination. Choked flow occurred in all high respiratory rate-high volume animals, 71% of high respiratory rate-medium volume (HRMV) animals, and 50% of medium respiratory rate-high volume (MRHV) animals but in no other combinations. Medium respiratory rate-medium volume (MRMV) resulted in the highest gas exchange of the combinations that did not induce choke. The HRMV and MRHV animals that did not choke had similar or higher gas exchange than MRMV. The theory predicted this behavior, along with spatial and temporal variations in alveolar gas partial pressures. Of the combinations that did not induce choked flow, MRMV provided the highest gas exchange. Alveolar gas transport is diffusion dominated and rapid during gas ventilation but is convection dominated and slow during TLV. Consequently, the usual alveolar gas equation is not applicable for TLV.

  7. Commercial applications of solar total energy systems. Volume 4. Appendices. Final report. [Solar Total Energy System Evaluation Program (STESEP) code

    Energy Technology Data Exchange (ETDEWEB)

    Boobar, M.G.; McFarland, B.L.; Nalbandian, S.J.; Willcox, W.W.; French, E.P.; Smith, K.E.

    1978-07-01

    A methodology has been developed by Atomics International under contract to the Department of Energy to define the applicability of solar total energy systems (STES) to the commercial sector (e.g., retail stores, shopping centers, offices, etc.) in the United States. Candidate STES concepts were selected to provide on-site power generation capability, as well as thermal energy for both heating and cooling applications. Each concept was evaluated on the basis of its cost effectiveness (i.e., as compared to other concepts) and its ability to ultimately penetrate and capture a significant segment of this market, thereby resulting in a saving of fossil fuel resources. This volume contains the appendices. Topics include deterministic insolation model computer code; building energy usage data; computer simulation programs for building energy demand analysis; model buildings for STES evaluation; Solar Total Energy System Evaluation Program (STESEP) computer code; transient simulation of STES concept; solar data tape analysis; program listings and sample output for use with TRNSYS; transient simulation, and financial parameters sensitivities. (WHK)

  8. Total pancreatectomy: Short- and long-term outcomes at a high-volume pancreas center

    Science.gov (United States)

    Zakaria, Hazem M; Stauffer, John A; Raimondo, Massimo; Woodward, Timothy A; Wallace, Michael B; Asbun, Horacio J

    2016-01-01

    AIM To identify the current indications and outcomes of total pancreatectomy at a high-volume center. METHODS A single institutional retrospective study of patients undergoing total pancreatectomy from 1995 to 2014 was performed. RESULTS One hundred and three patients underwent total pancreatectomy for indications including: Pancreatic ductal adenocarcinoma (n = 42, 40.8%), intraductal papillary mucinous neoplasms (n = 40, 38.8%), chronic pancreatitis (n = 8, 7.8%), pancreatic neuroendocrine tumors (n = 7, 6.8%), and miscellaneous (n = 6, 5.8%). The mean age was 66.2 years, and 59 (57.3%) were female. Twenty-four patients (23.3%) underwent a laparoscopic total pancreatectomy. Splenic preservation and portal vein resection and reconstruction were performed in 24 (23.3%) and 18 patients (17.5%), respectively. The 90 d major complications, readmission, and mortality rates were 32%, 17.5%, and 6.8% respectively. The 1-, 3-, 5-, and 7-year survival for patients with benign indications were 84%, 82%, 79.5%, and 75.9%, and for malignant indications were 64%, 40.4%, 34.7% and 30.9%, respectively. CONCLUSION Total pancreatectomy, including laparoscopic total pancreatectomy, appears to be an appropriate option for selected patients when treated at a high-volume pancreatic center and through a multispecialty approach. PMID:27721927

  9. Primary visual cortex volume and total neuron number are reduced in schizophrenia

    DEFF Research Database (Denmark)

    Dorph-Petersen, Karl-Anton; Pierri, Joseph H.; Wu, Qiang

    2007-01-01

    with schizophrenia reported an increased density of neurons in the primary visual cortex (Brodmann's area 17, BA17). The observed changes in visual processing may thus be reflected in structural changes in the circuitry of BA17. To characterize the structural changes further we used stereological methods based...... on unbiased principles of sampling (Cavalieri's principle and the optical fractionator) to estimate the total volume and neuron number of BA17 in postmortem brains from 10 subjects with schizophrenia and 10 matched normal comparison subjects. In addition, we assessed cortical thickness. We found a marked...... and significant reduction in total neuron number (25%) and volume (22%) of BA17 in the schizophrenia group relative to the normal comparison subjects. In contrast, we found no changes in neuronal density or cortical thickness between the two groups. Subjects with schizophrenia therefore have a smaller cortical...

  10. Large pore volume mesoporous copper particles and scaffold microporous carbon material obtained from an inorganic-organic nanohybrid material, copper-succinate-layered hydroxide.

    Science.gov (United States)

    Ghotbi, Mohammad Yeganeh; Bagheri, Narjes; Sadrnezhaad, S K

    2011-10-01

    Copper-succinate-layered hydroxide (CSLH), a new nanohybrid material, was synthesized as an inorganic-organic nanohybrid, in which organic moiety was intercalated between the layers of a single cation layered material, copper hydroxide nitrate. Microporous scaffold carbon material was obtained by thermal decomposition of the nanohybrid at 500 °C under argon atmosphere followed by acid washing process. Furthermore, the heat-treated product of the nanohybrid at 600 °C was ultrafine mesoporous metallic copper particles. The results of this study confirmed the great potential of CSLH to produce the carbon material with large surface area (580 m(2)/g) and high pore volume copper powder (2.04 cm(3)/g).

  11. Estimation of the total saliva volume produced per day in five-year-old children.

    Science.gov (United States)

    Watanabe, S; Ohnishi, M; Imai, K; Kawano, E; Igarashi, S

    1995-08-01

    Fifteen boys and 15 girls were asked to record for 2 days the time spent awake, eating meals or snacks, and sleeping. The salivary flow rates elicited by chewing foods were also determined. The mean flow rate (+/- SD) of unstimulated saliva was 0.26 +/- 0.16 ml/min and that of saliva while chewing six different foods was 3.6 +/- 0.8 ml/min. The mean times spent eating, and awake but not eating, were 80.8 +/- 27.3 and 820 +/- 59 min, respectively, and the volumes of saliva produced during those periods would average about 288 and 208 ml, respectively. If the flow rate is virtually zero during sleep, the estimated total salivary volume produced per day is calculated to be about 500 ml.

  12. Feasibility of Commercially Available, Fully Automated Hepatic CT Volumetry for Assessing Both Total and Territorial Liver Volumes in Liver Transplantation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Cheong Il; Kim, Se Hyung; Rhim, Jung Hyo; Yi, Nam Joon; Suh, Kyung Suk; Lee, Jeong Min; Han, Joon Koo; Choi, Byung Ihn [Seoul National University Hospital, Seoul (Korea, Republic of)

    2013-02-15

    To assess the feasibility of commercially-available, fully automated hepatic CT volumetry for measuring both total and territorial liver volumes by comparing with interactive manual volumetry and measured ex-vivo liver volume. For the assessment of total and territorial liver volume, portal phase CT images of 77 recipients and 107 donors who donated right hemiliver were used. Liver volume was measured using both the fully automated and interactive manual methods with Advanced Liver Analysis software. The quality of the automated segmentation was graded on a 4-point scale. Grading was performed by two radiologists in consensus. For the cases with excellent-to-good quality, the accuracy of automated volumetry was compared with interactive manual volumetry and measured ex-vivo liver volume which was converted from weight using analysis of variance test and Pearson's or Spearman correlation test. Processing time for both automated and interactive manual methods was also compared. Excellent-to-good quality of automated segmentation for total liver and right hemiliver was achieved in 57.1% (44/77) and 17.8% (19/107), respectively. For both total and right hemiliver volumes, there were no significant differences among automated, manual, and ex-vivo volumes except between automate volume and manual volume of the total liver (p = 0.011). There were good correlations between automate volume and ex-vivo liver volume ({gamma}= 0.637 for total liver and {gamma}= 0.767 for right hemiliver). Both correlation coefficients were higher than those with manual method. Fully automated volumetry required significantly less time than interactive manual method (total liver: 48.6 sec vs. 53.2 sec, right hemiliver: 182 sec vs. 244.5 sec). Fully automated hepatic CT volumetry is feasible and time-efficient for total liver volume measurement. However, its usefulness for territorial liver volumetry needs to be improved.

  13. Automated CT-based segmentation and quantification of total intracranial volume

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, Carlos; Wahlund, Lars-Olof; Westman, Eric [Karolinska Institute, Department of Neurobiology, Care Sciences and Society (NVS), Division of Clinical Geriatrics, Stockholm (Sweden); Edholm, Kaijsa; Cavallin, Lena; Muller, Susanne; Axelsson, Rimma [Karolinska Institute, Department of Clinical Science, Intervention and Technology, Division of Medical Imaging and Technology, Stockholm (Sweden); Karolinska University Hospital in Huddinge, Department of Radiology, Stockholm (Sweden); Simmons, Andrew [King' s College London, Institute of Psychiatry, London (United Kingdom); NIHR Biomedical Research Centre for Mental Health and Biomedical Research Unit for Dementia, London (United Kingdom); Skoog, Ingmar [Gothenburg University, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy, Gothenburg (Sweden); Larsson, Elna-Marie [Uppsala University, Department of Surgical Sciences, Radiology, Akademiska Sjukhuset, Uppsala (Sweden)

    2015-11-15

    To develop an algorithm to segment and obtain an estimate of total intracranial volume (tICV) from computed tomography (CT) images. Thirty-six CT examinations from 18 patients were included. Ten patients were examined twice the same day and eight patients twice six months apart (these patients also underwent MRI). The algorithm combines morphological operations, intensity thresholding and mixture modelling. The method was validated against manual delineation and its robustness assessed from repeated imaging examinations. Using automated MRI software, the comparability with MRI was investigated. Volumes were compared based on average relative volume differences and their magnitudes; agreement was shown by a Bland-Altman analysis graph. We observed good agreement between our algorithm and manual delineation of a trained radiologist: the Pearson's correlation coefficient was r = 0.94, tICVml[manual] = 1.05 x tICVml[automated] - 33.78 (R{sup 2} = 0.88). Bland-Altman analysis showed a bias of 31 mL and a standard deviation of 30 mL over a range of 1265 to 1526 mL. tICV measurements derived from CT using our proposed algorithm have shown to be reliable and consistent compared to manual delineation. However, it appears difficult to directly compare tICV measures between CT and MRI. (orig.)

  14. Precise quantification of dialysis using continuous sampling of spent dialysate and total dialysate volume measurement.

    Science.gov (United States)

    Argilés, A; Ficheux, A; Thomas, M; Bosc, J Y; Kerr, P G; Lorho, R; Flavier, J L; Stec, F; Adelé, C; Leblanc, M; Garred, L J; Canaud, B; Mion, H; Mion, C M

    1997-08-01

    The "gold standard" method to evaluate the mass balances achieved during dialysis for a given solute remains total dialysate collection (TDC). However, since handling over 100 liter volumes is unfeasible in our current dialysis units, alternative methods have been proposed, including urea kinetic modeling, partial dialysate collection (PDC) and more recently, monitoring of dialysate urea by on-line devices. Concerned by the complexity and costs generated by these devices, we aimed to adapt the simple "gold standard" TDC method to clinical practice by diminishing the total volumes to be handled. We describe a new system based on partial dialysate collection, the continuous spent sampling of dialysate (CSSD), and present its technical validation. Further, and for the first time, we report a long-term assessment of dialysis dosage in a dialysis clinic using both the classical PDC and the new CSSD system in a group of six stable dialysis patients who were followed for a period of three years. For the CSSD technique, spent dialysate was continuously sampled by a reversed automatic infusion pump at a rate of 10 ml/hr. The piston was automatically driven by the dialysis machine: switched on when dialysis started, off when dialysis terminated and held during the by pass periods. At the same time the number of production cycles of dialysate was monitored and the total volume of dialysate was calculated by multiplying the volume of the production chamber by the number of cycles. Urea and creatinine concentrations were measured in the syringe and the masses were obtained by multiplying this concentration by the total volume. CSSD and TDC were simultaneously performed in 20 dialysis sessions. The total mass of urea removed was calculated as 58038 and 60442 mmol/session (CSSD and TDC respectively; 3.1 +/- 1.2% variation; r = 0.99; y = 0.92x -28.9; P urea removal: 510 +/- 59 during the first year with PDC and 516 +/- 46 mmol/dialysis session during the third year, using CSSD

  15. The role of surgeon volume on patient outcome in total knee arthroplasty: a systematic review of the literature

    Directory of Open Access Journals (Sweden)

    Lau Rick L

    2012-12-01

    Full Text Available Abstract Background A number of factors have been identified as influencing total knee arthroplasty outcomes, including patient factors such as gender and medical comorbidity, technical factors such as alignment of the prosthesis, and provider factors such as hospital and surgeon procedure volumes. Recently, strategies aimed at optimizing provider factors have been proposed, including regionalization of total joint arthroplasty to higher volume centers, and adoption of volume standards. To contribute to the discussions concerning the optimization of provider factors and proposals to regionalize total knee arthroplasty practices, we undertook a systematic review to investigate the association between surgeon volume and primary total knee arthroplasty outcomes. Methods We performed a systematic review examining the association between surgeon volume and primary knee arthroplasty outcomes. To be included in the review, the study population had to include patients undergoing primary total knee arthroplasty. Studies had to report on the association between surgeon volume and primary total knee arthroplasty outcomes, including perioperative mortality and morbidity, patient-reported outcomes, or total knee arthroplasty implant survivorship. There were no restrictions placed on study design or language. Results Studies were variable in defining surgeon volume (‘low’: 5 to >70 total knee arthroplasty per year. Mortality rate, survivorship and thromboembolic events were not found to be associated with surgeon volume. We found a significant association between low surgeon volume and higher rate of infection (0.26% - 2.8% higher, procedure time (165 min versus 135 min, longer length of stay (0.4 - 2.13 days longer, transfusion rate (13% versus 4%, and worse patient reported outcomes. Conclusions Findings suggest a trend towards better outcomes for higher volume surgeons, but results must be interpreted with caution.

  16. THE INFLUENCE OF THE MAIN PARAMETERS OF TRAIN TRAFFIC VOLUME ON TOTAL PROFITS OF RAILWAYS

    Directory of Open Access Journals (Sweden)

    H. YA. Mozolevich

    2015-04-01

    Full Text Available Purpose. The paper is aimed to influence analysis of parameters such as the number of trains on the section and the length of freight trains, the total profit of the railway and determination of total profit of Prydniprovsk railway for major parts of the trains handling; the determination of the specific rate of return on 1 kilometer operational length of each individual link in the rail network. Methodology. To achieve this goal the simulation models of the sections of railway polygon and the simulation of cargo trains have been developed. On the basis of obtained results the dependence of the main parameters of train traffic and their impact on the overall profit of the railway was determined. Findings. On the basis of the conducted studies the functions operating costs for each section were developed to determine the optimal routes crossing of trains and choice of rational parameters. The operating costs, revenue, total profit of railways and certain impact parameters of train traffic volume on the economic performance of railway transport were calculated with their help. It is determined that freight trains, length 53-56 of a conventional car is optimal to pass and loading area should be 75-85% of the available crossing capacity. Taking into account given results, the electrification of the sections with diesel traction (due to the significant cost of diesel fuel is the priority development of railway transport at the possible increase in size of the movement. Originality. Authors have improved the technology of determining the total profits of railways on the basis of variables train traffic volumes. For the first time the specific rate of profit on the 1 kilometer operational length of the section depending on the size of the average daily traffic is identified and proposed to use to determine the investment attractiveness of the railways. The simulation models of individual sections of the real train polygon at Prydniprovsk railway were

  17. Indications and Early Outcomes for Total Pancreatectomy at a High-Volume Pancreas Center

    Directory of Open Access Journals (Sweden)

    Monika S. Janot

    2010-01-01

    Full Text Available Background. This study aimed to analyse the most common current indications for total pancreatectomy (TP at a high-volume pancreas center. Method. Prospectively collected data on indications and short-term outcome of all TP's performed from January 2004 until June 2008 were analysed. Results. The total pancreatectomies (TP were 63, i.e., 6.7% of all pancreatic procedures (=948. Indications for TP were classified into 4 groups: tumors of advanced stage, =23 (36.5%, technical problems due to soft pancreatic tissue, =18 (28.6%, troubles due to perioperative surgical complications, =15 (23.8%, and therapy-resistant pain due to chronic pancreatitis, =7 (11.1%. Surgical complications occurred in 23 patients (36.5%. The mortality in elective TP was 6.25%. Median postoperative stay was 21 days. Mortality, morbidity and the other perioperative parameters differed substantially according to the indication for pancreatectomy. Conclusion. Total pancreatectomy is definitely indicated for a limited range of elective and emergency situations. Indications can be: size or localisation of pancreatic tumor, trouble, technical diffuculties and therapy-refractory pain in chronic pancreatitis. A TP due to perioperative complications (troubles after pancreatic resections is doomed by extremely high morbidity and mortality and should be avoided.

  18. Reference values for total blood volume and cardiac output in humans

    Energy Technology Data Exchange (ETDEWEB)

    Williams, L.R. [Indiana Univ., South Bend, IN (United States). Division of Liberal Arts and Sciences

    1994-09-01

    Much research has been devoted to measurement of total blood volume (TBV) and cardiac output (CO) in humans but not enough effort has been devoted to collection and reduction of results for the purpose of deriving typical or {open_quotes}reference{close_quotes} values. Identification of normal values for TBV and CO is needed not only for clinical evaluations but also for the development of biokinetic models for ultra-short-lived radionuclides used in nuclear medicine (Leggett and Williams 1989). The purpose of this report is to offer reference values for TBV and CO, along with estimates of the associated uncertainties that arise from intra- and inter-subject variation, errors in measurement techniques, and other sources. Reference values are derived for basal supine CO and TBV in reference adult humans, and differences associated with age, sex, body size, body position, exercise, and other circumstances are discussed.

  19. Blood volume, blood pressure and total body sodium: internal signalling and output control

    DEFF Research Database (Denmark)

    Bie, P

    2009-01-01

    , and under experimental conditions, ABP is a powerful, independent controller of NaEx. Blood volume is a function of dietary salt intake; however, ABP is not, at least not in steady states. A transient increase in ABP after a step-up in sodium intake could provide a causal relationship between ABP......Total body sodium and arterial blood pressure (ABP) are mutually dependent variables regulated by complex control systems. This review addresses the role of ABP in the normal control of sodium excretion (NaEx), and the physiological control of renin secretion. NaEx is a pivotal determinant of ABP...... and the regulation of NaEx via a hypothetical integrative control system. However, recent data show that subtle sodium loading (simulating salty meals) causes robust natriuresis without changes in ABP. Changes in ABP are not necessary for natriuresis. Normal sodium excretion is not regulated by pressure. Plasma...

  20. Total-liver-volume perfusion CT using 3-D image fusion to improve detection and characterization of liver metastases

    NARCIS (Netherlands)

    Meijerink, Martijn; Waesberghe, van Jan; Weide, van der Lineke; Tol, van den Petrousjka; Meijer, Sybren; Kuijk, van Cornelis

    2008-01-01

    The purpose of this study was to evaluate the feasibility of a totalliver- volume perfusion CT (CTP) technique for the detection and characterization of livermetastases. Twenty patients underwent helical CT of the total liver volume before and 11 times after intravenous contrast-material injection.

  1. Total-liver-volume perfusion CT using 3-D image fusion to improve detection and characterization of liver metastases

    NARCIS (Netherlands)

    Meijerink, Martijn; Waesberghe, van Jan; Weide, van der Lineke; Tol, van den Petrousjka; Meijer, Sybren; Kuijk, van Cornelis

    2008-01-01

    The purpose of this study was to evaluate the feasibility of a totalliver- volume perfusion CT (CTP) technique for the detection and characterization of livermetastases. Twenty patients underwent helical CT of the total liver volume before and 11 times after intravenous contrast-material injection.

  2. Total Mercury, Methylmercury, Methylmercury Production Potential, and Ancillary Streambed-Sediment and Pore-Water Data for Selected Streams in Oregon, Wisconsin, and Florida, 2003-04

    Science.gov (United States)

    Marvin-DiPasquale, Mark C.; Lutz, Michelle A.; Krabbenhoft, David P.; Aiken, George R.; Orem, William H.; Hall, Britt D.; DeWild, John F.; Brigham, Mark E.

    2008-01-01

    Mercury contamination of aquatic ecosystems is an issue of national concern, affecting both wildlife and human health. Detailed information on mercury cycling and food-web bioaccumulation in stream settings and the factors that control these processes is currently limited. In response, the U.S. Geological Survey (USGS) National Water-Quality Assessment Program (NAWQA) conducted detailed studies from 2002 to 2006 on various media to enhance process-level understanding of mercury contamination, biogeochemical cycling, and trophic transfer. Eight streams were sampled for this study: two streams in Oregon, and three streams each in Wisconsin and Florida. Streambed-sediment and pore-water samples were collected between February 2003 and September 2004. This report summarizes the suite of geochemical and microbial constituents measured, the analytical methods used, and provides the raw data in electronic form for both bed-sediment and pore-water media associated with this study.

  3. 21 CFR 201.323 - Aluminum in large and small volume parenterals used in total parenteral nutrition.

    Science.gov (United States)

    2010-04-01

    ... used in total parenteral nutrition. 201.323 Section 201.323 Food and Drugs FOOD AND DRUG ADMINISTRATION... parenteral nutrition. (a) The aluminum content of large volume parenteral (LVP) drug products used in total parenteral nutrition (TPN) therapy must not exceed 25 micrograms per liter (µg/L). (b) The package insert...

  4. Total volume and composition of fluid intake and mortality in older women: a cohort study

    Science.gov (United States)

    Lim, Wai H; Wong, Germaine; Lewis, Joshua R; Lok, Charmaine E; Polkinghorne, Kevan R; Hodgson, Jonathan; Lim, Ee M; Prince, Richard L

    2017-01-01

    Objectives The health benefits of ‘drinking at least 8 glasses of water a day” in healthy individuals are largely unproven. We aimed to examine the relationship between total fluid and the sources of fluid consumption, risk of rapid renal decline, cardiovascular disease (CVD) mortality and all-cause mortality in elderly women. Design, setting and participants We conducted a longitudinal analysis of a population-based cohort study of 1055 women aged ≥70 years residing in Australia. Main outcome measures The associations between total daily fluid intake (defined as total volume of beverage excluding alcohol and milk) and the types of fluid (water, black tea, coffee, milk and other fluids) measured as cups per day and rapid renal decline, CVD and all-cause mortality were assessed using adjusted logistic and Cox regression analyses. Results Over a follow-up period of 10 years, 70 (6.6%) experienced rapid renal decline and 362 (34.4%) died, of which 142 (13.5%) deaths were attributed to CVD. The median (IQR) intake of total fluid was 10.4 (8.5–12.5) cups per day, with water (median (IQR) 4 (2–6) cups per day) and black tea (median (IQR) 3 (1–4) cups per day) being the most frequent type of fluid consumed. Every cup per day higher intake of black tea was associated with adjusted HRs of 0.90 (95% CI 0.81 to 0.99) and 0.92 (95% CI 0.86 to 0.98) for CVD mortality and all-cause mortality, respectively. There were no associations between black tea intake and rapid renal decline, or between the quantity or type of other fluids, including water intake, and any clinical outcomes. Conclusions Habitual higher intake of black tea may potentially improve long-term health outcomes, independent of treating traditional CVD risk factors, but validation of our study findings is essential. PMID:28341683

  5. Total volume and composition of fluid intake and mortality in older women: a cohort study.

    Science.gov (United States)

    Lim, Wai H; Wong, Germaine; Lewis, Joshua R; Lok, Charmaine E; Polkinghorne, Kevan R; Hodgson, Jonathan; Lim, Ee M; Prince, Richard L

    2017-03-24

    The health benefits of 'drinking at least 8 glasses of water a day" in healthy individuals are largely unproven. We aimed to examine the relationship between total fluid and the sources of fluid consumption, risk of rapid renal decline, cardiovascular disease (CVD) mortality and all-cause mortality in elderly women. We conducted a longitudinal analysis of a population-based cohort study of 1055 women aged ≥70 years residing in Australia. The associations between total daily fluid intake (defined as total volume of beverage excluding alcohol and milk) and the types of fluid (water, black tea, coffee, milk and other fluids) measured as cups per day and rapid renal decline, CVD and all-cause mortality were assessed using adjusted logistic and Cox regression analyses. Over a follow-up period of 10 years, 70 (6.6%) experienced rapid renal decline and 362 (34.4%) died, of which 142 (13.5%) deaths were attributed to CVD. The median (IQR) intake of total fluid was 10.4 (8.5-12.5) cups per day, with water (median (IQR) 4 (2-6) cups per day) and black tea (median (IQR) 3 (1-4) cups per day) being the most frequent type of fluid consumed. Every cup per day higher intake of black tea was associated with adjusted HRs of 0.90 (95% CI 0.81 to 0.99) and 0.92 (95% CI 0.86 to 0.98) for CVD mortality and all-cause mortality, respectively. There were no associations between black tea intake and rapid renal decline, or between the quantity or type of other fluids, including water intake, and any clinical outcomes. Habitual higher intake of black tea may potentially improve long-term health outcomes, independent of treating traditional CVD risk factors, but validation of our study findings is essential. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  6. TOTAL WOOD VOLUME ESTIMATION OF EUCALYPTUS SPECIES BY IMAGES OF LANDSAT SATELLITE

    Directory of Open Access Journals (Sweden)

    Elias Fernando Berra

    2012-12-01

    Full Text Available http://dx.doi.org/10.5902/198050987566Models relating spectral answers with biophysical parameters aim estimate variables, like wood volume, without the necessity of frequent field measurements. The objective was to develop models to estimate wood volume by Landsat 5 TM images, supported by regional forest inventory data. The image was geo-referenced and converted to spectral reflectance. After, the images-index NDVI (Normalized Difference Vegetation Index and SR (Simple Ratio was generated. The reflectance values of the bands (TM1, TM2, TM3 e TM4 and of the indices (NDVI and SR was related with the wood volume. The biggest correlation with volume was with the NDVI and SR indices. The variables selection was made by Stepwise method, which returned three regression models as significant to explain the variation in volume. Finally, the best fitted model was selected (volume = -830,95 + 46,05 (SR + 107,47 (TM2, which was applied on the Landsat image where the pixels had started to represent the estimated volume in m³/ha on the Eucalyptus sp. production units. This model, significant at 95% confidence level, explains 68% of the wood volume variation.

  7. Storage of hydrogen at 303 K in graphite slitlike pores from grand canonical Monte Carlo simulation.

    Science.gov (United States)

    Kowalczyk, Piotr; Tanaka, Hideki; Hołyst, Robert; Kaneko, Katsumi; Ohmori, Takumi; Miyamoto, Junichi

    2005-09-15

    Grand canonical Monte Carlo (GCMC) simulations were used for the modeling of the hydrogen adsorption in idealized graphite slitlike pores. In all simulations, quantum effects were included through the Feynman and Hibbs second-order effective potential. The simulated surface excess isotherms of hydrogen were used for the determination of the total hydrogen storage, density of hydrogen in graphite slitlike pores, distribution of pore sizes and volumes, enthalpy of adsorption per mole, total surface area, total pore volume, and average pore size of pitch-based activated carbon fibers. Combining experimental results with simulations reveals that the density of hydrogen in graphite slitlike pores at 303 K does not exceed 0.014 g/cm(3), that is, 21% of the liquid-hydrogen density at the triple point. The optimal pore size for the storage of hydrogen at 303 K in the considered pore geometry depends on the pressure of storage. For lower storage pressures, p optimal pore width is equal to a 2.2 collision diameter of hydrogen (i.e., 0.65 nm), whereas, for p congruent with 50MPa, the pore width is equal to an approximately 7.2 collision diameter of hydrogen (i.e., 2.13 nm). For the wider pores, that is, the pore width exceeds a 7.2 collision diameter of hydrogen, the surface excess of hydrogen adsorption is constant. The importance of quantum effects is recognized in narrow graphite slitlike pores in the whole range of the hydrogen pressure as well as in wider ones at high pressures of bulk hydrogen. The enthalpies of adsorption per mole for the considered carbonaceous materials are practically constant with hydrogen loading and vary within the narrow range q(st) congruent with 7.28-7.85 kJ/mol. Our systematic study of hydrogen adsorption at 303 K in graphite slitlike pores gives deep insight into the timely problem of hydrogen storage as the most promising source of clean energy. The calculated maximum storage of hydrogen is equal to approximately 1.4 wt %, which is far from

  8. Clinical outcomes and case volume effect of transanal total mesorectal excision for rectal cancer: a systematic review.

    Science.gov (United States)

    Deijen, C L; Tsai, A; Koedam, T W A; Veltcamp Helbach, M; Sietses, C; Lacy, A M; Bonjer, H J; Tuynman, J B

    2016-12-01

    Transanal total mesorectal excision (TaTME) has been developed to improve quality of TME for patients with mid and low rectal cancer. However, despite enthusiastic uptake and teaching facilities, concern exists for safe introduction. TaTME is a complex procedure and potentially a learning curve will hamper clinical outcome. With this systematic review, we aim to provide data regarding morbidity and safety of TaTME. A systematic literature search was performed in MEDLINE (PubMed), EMBASE (Ovid) and Cochrane Library. Case reports, cohort series and comparative series on TaTME for rectal cancer were included. To evaluate a potential effect of case volume, low-volume centres (n ≤ 30 total volume) were compared with high-volume centres (n > 30 total volume). Thirty-three studies were identified (three case reports, 25 case series, five comparative studies), including 794 patients. Conversion was performed in 3.0% of the procedures. The complication rate was 40.3, and 11.5% were major complications. The quality of the mesorectum was "complete" in 87.6%, and the circumferential resection margin (CRM) was involved in 4.7%. In low- versus high-volume centres, the conversion rate was 4.3 versus 2.7%, and major complication rates were 12.2 versus 10.5%, respectively. TME quality was "complete" in 80.5 versus 89.7%, and CRM involvement was 4.8 and 4.5% in low- versus high-volume centres, respectively. TaTME for mid and low rectal cancer is a promising technique; however, it is associated with considerable morbidity. Safe implementation of the TaTME should include proctoring and quality assurance preferably within a trial setting.

  9. Parmelia sulcata lichen transplants positioning towards wind direction (Part I): precipitation volumes, total element deposition and lichen element content

    NARCIS (Netherlands)

    Marques, A.P.; Freitas, M.C.; Wolterbeek, H. Th.; Verburg, T.

    2009-01-01

    Parmelia sulcata transplants were used in three different exposure systems, focused on three different influxes: free influx, horizontal influx and vertical influx. The total element deposition and the precipitation volumes were found to be positively correlated for Fe and Ni only. The element conte

  10. Functional Response of Tumor Vasculature to PaCO2: Determination of Total and Microvascular Blood Volume by MRI

    Directory of Open Access Journals (Sweden)

    Scott D. Packard

    2003-07-01

    Full Text Available In order to identify differences in functional activity, we compared the reactivity of glioma vasculature and the native cerebral vasculature to both dilate and constrict in response to altered PaCO2. Gliomas were generated by unilateral implantation of U87MGdEGFR human glioma tumor cells into the striatum of adult female athymic rats. Relative changes in total and microvascular cerebral blood volume were determined by steady state contrast agent-enhanced magnetic resonance imaging for transitions from normocarbia to hypercarbia and hypocarbia. Although hypercarbia induced a significant increase in both total and microvascular blood volume in normal brain and glioma, reactivity of glioma vasculature was significantly blunted in comparison to normal striatum; glioma total CBV increased by 0.6±0.1%/mm Hg CO2 whereas normal striatum increased by 1.5±0.2%/mm Hg CO2, (P < .0001, group t-test. Reactivity of microvascular blood volume was also significantly blunted. In contrast, hypocarbia decreased both total and microvascular blood volumes more in glioma than in normal striatum. These results indicate that cerebral blood vessels derived by tumor-directed angiogenesis do retain reactivity to CO2. Furthermore, reduced reactivity of tumor vessels to a single physiological perturbation, such as hypercarbia, should not be construed as a generalized reduction of functional activity of the tumor vascular bed.

  11. Total Automation for the Core Laboratory: Improving the Turnaround Time Helps to Reduce the Volume of Ordered STAT Tests.

    Science.gov (United States)

    Ialongo, Cristiano; Porzio, Ottavia; Giambini, Ilio; Bernardini, Sergio

    2016-06-01

    The transition to total automation represents the greatest leap for a clinical laboratory, characterized by a totally new philosophy of process management. We have investigated the impact of total automation on core laboratory efficiency and its effects on the clinical services related to STAT tests. For this purpose, a 47-month retrospective study based on the analysis of 44,212 records of STAT cardiac troponin I (CTNI) tests was performed. The core laboratory reached a new efficiency level 3 months after the implementation of total automation. Median turnaround time (TAT) was reduced by 14.9±1.5 min for the emergency department (p < 0.01), reaching 41.6±1.2 min. In non-emergency departments, median TAT was reduced by 19.8±2.2 min (p < 0.01), reaching 52±1.3 min. There was no change in the volume of ordered STAT CTNI tests by the emergency department (p = 0.811), whereas for non-emergency departments there was a reduction of 115.7±50 monthly requests on average (p = 0.026). The volume of ordered tests decreased only in time frames of the regular shift following the morning round. Thus, total automation significantly improves the core laboratory efficiency in terms of TAT. As a consequence, the volume of STAT tests ordered by hospital departments (except for the emergency department) decreased due to reduced duplicated requests.

  12. Experimental Study on Pore Distribution Characters and Convert Rate of CaO

    Institute of Scientific and Technical Information of China (English)

    Li JIA; Yanyan ZENG; Tao ZHANG

    2005-01-01

    During the reaction between calcium sorbents and SO2, calcium sorbents are first calcined and converted into CaO. CaO can be obtained by calcining Ca(OH)2 or CaCO3. The porosity of the sorbent is increased because of calcination and is decreased because of sulfurization. In the calcination process H2O or CO2 is escaped from the particles and pores are formed in particles. The reaction or convert rate of CaO is influenced strongly by the pore structure characters. From Ca(OH)2 to CaO the escape velocity of H2O or its mass transfer is one of the key factors influencing the pore forming. During calcination process different heating velocity, different heating time and temperature were suggested. The temperature rising rate and calcining temperature play important role to the pore structure. The convert rates of CaO obtained through different calcining conditions were investigated experimentally. Some interesting results were showed that the calcium utilization of CaO particles is determined not only by the special surface area and total pore volume, but also by pore-size distribution. The main factor influencing the sulfation is the pore diameter distribution at lower sulfation temperature. For higher reaction temperature specific volume is the important reason. But pore-size distribution is strongly influenced by heat flux and temperature in the calcining process.

  13. Comparison of Total Kidney Volume Quantification Methods in Autosomal Dominant Polycystic Disease for a Comprehensive Disease Assessment.

    Science.gov (United States)

    Turco, Dario; Busutti, Marco; Mignani, Renzo; Magistroni, Riccardo; Corsi, Cristiana

    2017-01-01

    In recent times, the scientific community has been showing increasing interest in the treatments aimed at slowing the progression of the autosomal dominant polycystic kidney disease (ADPKD). Therefore, in this paper, we test and evaluate the performance of several available methods for total kidney volume (TKV) computation in ADPKD patients - from echography to MRI - in order to optimize patient classification. Two methods based on geometric assumptions (mid-slice [MS], ellipsoid [EL]) and a third one on true contour detection were tested on 40 ADPKD patients at different disease stage using MRI. The EL method was also tested using ultrasound images in a subset of 14 patients. Their performance was compared against TKVs derived from reference manual segmentation of MR images. Patient clinical classification was also performed based on computed volumes. Kidney volumes derived from echography significantly underestimated reference volumes. Geometric-based methods applied to MR images had similar acceptable results. The highly automated method showed better performance. Volume assessment was accurate and reproducible. Importantly, classification resulted in 79, 13, 10, and 2.5% of misclassification using kidney volumes obtained from echo and MRI applying the EL, the MS and the highly automated method respectively. Considering the fact that the image-based technique is the only approach providing a 3D patient-specific kidney model and allowing further analysis including cyst volume computation and monitoring disease progression, we suggest that geometric assumption (e.g., EL method) should be avoided. The contour-detection approach should be used for a reproducible and precise morphologic classification of the renal volume of ADPKD patients. © 2017 S. Karger AG, Basel.

  14. Volume-dependent hemodynamic effects of blood collection in canine donors - evaluation of 13% and 15% of total blood volume depletion

    Directory of Open Access Journals (Sweden)

    RUI R.F. FERREIRA

    2015-03-01

    Full Text Available Background: There is no consensus regarding the blood volume that could be safely donated by dogs, ranging from 11 to 25% of its total blood volume (TBV. No previous studies evaluated sedated donors.Aim: To evaluate the hemodynamic effects of blood collection from sedated and non-sedated dogs and to understand if such effects were volume-dependent.Materials and Methods: Fifty three donations of 13% of TBV and 20 donations of 15% TBV were performed in dogs sedated with diazepam and ketamine. Additionally, a total of 30 collections of 13% TBV and 20 collections of 15% TBV were performed in non-sedated dogs. Non-invasive arterial blood pressures and pulse rates were registered before and 15 min after donation. Results: Post-donation pulse rates increased significantly in both sedated groups, with higher differences in the 15% TBV collections. Systolic arterial pressures decreased significantly in these groups, while diastolic pressures increased significantly in 13% TBV donations. Non-sedated groups revealed a slight, but significant, SBP decrease. No clinical signs related to donations were registered.Conclusion: These results suggest that the collection of 15% TBV in sedated donors induces hemodynamic variations that may compromise the harmlessness of the procedure, while it seems to be a safe procedure in non-sedated dogs.

  15. Fort Hood Solar Total Energy Project. Volume III. Engineering drawings. Final report

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1979-01-01

    Engineering drawings are presented for the Solar Total Energy System at Fort Hood, Texas. Drawings are given for the solar collector subsystem, power conversion subsystem, instrumentation and control subsystem, thermal storage subsystem, site preparation, thermal storage area piping and equipment layout, heating/cooling and domestic hot water subsystem, STES building and facility, and electrical distribution. (WHK)

  16. Moderate Intensity Resistance Training Significantly Elevates Testosterone following Upper Body and Lower Body Bouts When Total Volume is Held Constant

    Directory of Open Access Journals (Sweden)

    Robert Rietjens

    2015-10-01

    Full Text Available Introduction: It is unknown whether resistance training intensity or total volume of work affects the acute testosterone response to a greater extent. Purpose: Therefore, the circulating testosterone response was investigated following four resistance training protocols where total volume of work was held constant: moderate intensity (70% 1RM upper body (bench press, bent barbell row, and military press, moderate intensity lower body (squat and deadlift, high intensity (90% 1RM upper body, high intensity lower body. Methods: Total volume of work performed by each participant between protocols was maintained by adjusting the number of sets and or repetitions performed. Ten healthy, resistance trained men volunteered, and performed exercise protocols on separate days in a counterbalanced order. Capillary blood was obtained via finger stick at baseline (pre, immediately following the exercise session (post, and 1h post for the determination of testosterone concentration. Data were analyzed using a factorial ANOVA and significance was accepted at p≤ 0.05. Results: Both moderate intensity resistance protocols (upper and lower body significantly increased testosterone concentration (p=0.026, and p=0.024 respectively, whereas the high intensity protocols elevated testosterone but failed to achieve significance (upper p=0.272, lower p=0.658. No difference was noted in post session testosterone concentration between upper and lower body protocols for either moderate (p=0.248 or high intensity (p=0.990. Conclusion: This may be useful for novice resistance trained individuals because it provides evidence that moderate intensity is sufficient to increase testosterone compared to high intensity protocols that could be associated with a greater risk of injury. Keywords: hormone response, equal total work, high intensity protocol

  17. Institutional applications of solar total-energy systems. Draft final report. Volume 2. Appendixes

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-07-01

    The appendices present the analytical basis for the analysis of solar total energy (STE) systems. A regional-climate model and a building-load requirements model are developed, along with fuel-price scenarios. Life-cycle costs are compared for conventional-utility, total energy, and STE systems. Thermal STE system design trade-offs are performed and thermal STE system performance is determined. The sensitivity of STE competitiveness to fuel prices is examined. The selection of the photovoltaic array is briefly discussed. The institutional-sector decision processes are analyzed. Hypothetical regional back-up rates and electrical-energy costs are calculated. The algorithms and equations used in operating the market model are given, and a general methodology is developed for projecting the size of the market for STE systems and applied to each of 8 institutional subsectors. (LEW)

  18. Articulated Total Body Model Enhancements. Volume 3. Programmer’s Guide

    Science.gov (United States)

    1988-02-01

    BY U INDEX OF NTAB ARRAY. FRCDFL C DERIVATIVE, FUNCTION OR INTEGRAL IS EVALUATED AS N =0,1 OR 2. FRCDFL C ETAB (N) - INDEX TO TAB ARRAY FOR REAL DATA...6. Leetch, B.D., Bowman, W.L., "Articulated Total Body (AmB) VIEW Program Software Report," Report Nos. AMRL-TR-81-111, Vols 1 & 2, June * 1983 (NTIS

  19. Application analysis of solar total energy systems to the residential sector. Volume II, energy requirements. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1979-07-01

    This project analyzed the application of solar total energy systems to appropriate segments of the residential sector and determined their market penetration potential. This volume covers the work done on energy requirements definition and includes the following: (1) identification of the single-family and multi-family market segments; (2) regionalization of the United States; (3) electrical and thermal load requirements, including time-dependent profiles; (4) effect of conservation measures on energy requirements; and (5) verification of simulated load data with real data.

  20. Viability Assessment of a Repository at Yucca Mountain. Volume 3: Total System Performance Assessment

    Energy Technology Data Exchange (ETDEWEB)

    None

    1998-12-01

    This volume reports the development of TSPA for the VA. This first section defines the general process involved in developing any TSPA, it describes the overall TSPA process as implemented by programs in the US and elsewhere in the world, and discusses the acceptability of TSPA as a process or tool for analyzing a nuclear waste repository system. Section 2 discusses the more specific use of the TSPA process for the TSPA-VA for Yucca Mountain, including goals, approach, and methods. It also includes a very brief synopsis of TSPA-VA results. Section 3 briefly discusses each of the component models that comprise the TSPA-VA. Each TSPA component model represents a discrete set of processes. The TSPA-VA components are: unsaturated zone flow, thermal hydrology, near- field geochemical environment, waste package degradation, waste form alteration and mobilization, unsaturated zone transport, saturated zone flow and transport, and biosphere. For each of these components, this section introduces the conceptualization of each individual process, describes the data sources, and discusses model parameter development and computer methods used to simulate each component. Section 4 explains the mechanics of how the individual TSPA components were combined into a ''base case'' and then provides the ''expected value'' results of a deterministic base case analysis. Section 4 also contains a description of the probabilistic analyses and results that help determine the relative importance of the various TSPA components and the data used to describe the components. Section 5 addresses sensitivity studies run for each of the TSPA components to understand how uncertainty in various parameters within a component change the TSPA results. Section 6 presents the findings of the sensitivity studies run on the various components in Section 5, and prioritizes the findings of the entire set of uncertainty and sensitivity studies of the components relative

  1. Total-system performance assessment for Yucca Mountain - SNL second iteration (TSPA-1993); Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.L.; Gauthier, J.H.; Barnard, R.W.; Barr, G.E.; Dockery, H.A.; Dunn, E.; Eaton, R.R.; Guerin, D.C.; Lu, N.; Martinez, M.J. [and others

    1994-04-01

    Sandia National Laboratories has completed the second iteration of the periodic total-system performance assessments (TSPA-93) for the Yucca Mountain Site Characterization Project (YMP). These analyses estimate the future behavior of a potential repository for high-level nuclear waste at the Yucca Mountain, Nevada, site under consideration by the Department of Energy. TSPA-93 builds upon previous efforts by emphasizing YMP concerns relating to site characterization, design, and regulatory compliance. Scenarios describing expected conditions (aqueous and gaseous transport of contaminants) and low-probability events (human-intrusion drilling and volcanic intrusion) are modeled. The hydrologic processes modeled include estimates of the perturbations to ambient conditions caused by heating of the repository resulting from radioactive decay of the waste. Hydrologic parameters and parameter probability distributions have been derived from available site data. Possible future climate changes are modeled by considering two separate groundwater infiltration conditions: {open_quotes}wet{close_quotes} with a mean flux of 10 mm/yr, and {open_quotes}dry{close_quotes} with a mean flux of 0.5 mm/yr. Two alternative waste-package designs and two alternative repository areal thermal power densities are investigated. One waste package is a thin-wall container emplaced in a vertical borehole, and the second is a container designed with corrosion-resistant and corrosion-allowance walls emplaced horizontally in the drift. Thermal power loadings of 57 kW/acre (the loading specified in the original repository conceptual design) and 114 kW/acre (a loading chosen to investigate effects of a {open_quotes}hot repository{close_quotes}) are considered. TSPA-93 incorporates significant new detailed process modeling, including two- and three-dimensional modeling of thermal effects, groundwater flow in the saturated-zone aquifers, and gas flow in the unsaturated zone.

  2. Total-system performance assessment for Yucca Mountain - SNL second iteration (TSPA-1993); Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.L.; Barnard, R.W.; Barr, G.E.; Dockery, H.A.; Dunn, E.; Eaton, R.R.; Martinez, M.J. [Sandia National Labs., Albuquerque, NM (United States); Gauthier, J.H.; Guerin, D.C.; Lu, N. [and others

    1994-04-01

    Sandia National Laboratories has completed the second iteration of the periodic total-system performance assessments (TSPA-93) for the Yucca Mountain Site Characterization Project (YMP). These analyses estimate the future behavior of a potential repository for high-level nuclear waste at the Yucca Mountain, Nevada, site under consideration by the Department of Energy. TSPA-93 builds upon previous efforts by emphasizing YMP concerns relating to site characterization, design, and regulatory compliance. Scenarios describing expected conditions (aqueous and gaseous transport of contaminants) and low-probability events (human-intrusion drilling and volcanic intrusion) are modeled. The hydrologic processes modeled include estimates of the perturbations to ambient conditions caused by heating of the repository resulting from radioactive decay of the waste. Hydrologic parameters and parameter probability distributions have been derived from available site data. Possible future climate changes are modeled by considering two separate groundwater infiltration conditions: {open_quotes}wet{close_quotes} with a mean flux of 10 mm/yr, and {open_quotes}dry{close_quotes} with a mean flux of 0.5 mm/yr. Two alternative waste-package designs and two alternative repository areal thermal power densities are investigated. One waste package is a thin-wall container emplaced in a vertical borehole, and the second is a container designed with corrosion-resistant and corrosion-allowance walls emplaced horizontally in the drift. Thermal power loadings of 57 kW/acre (the loading specified in the original repository conceptual design) and 114 kW/acre (a loading chosen to investigate effects of a {open_quotes}hot repository{close_quotes}) are considered. TSPA-93 incorporates significant new detailed process modeling, including two- and three-dimensional modeling of thermal effects, groundwater flow in the saturated-zone aquifers, and gas flow in the unsaturated zone.

  3. The Prognostic Value of Residual Volume/Total Lung Capacity in Patients with Chronic Obstructive Pulmonary Disease.

    Science.gov (United States)

    Shin, Tae Rim; Oh, Yeon-Mok; Park, Joo Hun; Lee, Keu Sung; Oh, Sunghee; Kang, Dae Ryoung; Sheen, Seungsoo; Seo, Joon Beom; Yoo, Kwang Ha; Lee, Ji-Hyun; Kim, Tae-Hyung; Lim, Seong Yong; Yoon, Ho Il; Rhee, Chin Kook; Choe, Kang-Hyeon; Lee, Jae Seung; Lee, Sang-Do

    2015-10-01

    The prognostic role of resting pulmonary hyperinflation as measured by residual volume (RV)/total lung capacity (TLC) in chronic obstructive pulmonary disease (COPD) remains poorly understood. Therefore, this study aimed to identify the factors related to resting pulmonary hyperinflation in COPD and to determine whether resting pulmonary hyperinflation is a prognostic factor in COPD. In total, 353 patients with COPD in the Korean Obstructive Lung Disease cohort recruited from 16 hospitals were enrolled. Resting pulmonary hyperinflation was defined as RV/TLC ≥ 40%. Multivariate logistic regression analysis demonstrated that older age (P = 0.001), lower forced expiratory volume in 1 second (FEV1) (P hyperinflation. Multivariate Cox regression model that included age, gender, dyspnea scale, SGRQ, RV/TLC, and 6-min walking distance revealed that an older age (HR = 1.07, P = 0.027), a higher RV/TLC (HR = 1.04, P = 0.025), and a shorter 6-min walking distance (HR = 0.99, P hyperinflation in COPD. RV/TLC is an independent risk factor for all-cause mortality in COPD.

  4. Evaluation of the effect of varying the workability in concrete pore structure by using X-ray microtomography

    Directory of Open Access Journals (Sweden)

    E. E. Bernardes

    Full Text Available The useful life of concrete is associated with the penetrative ability of aggressive agents on their structures. Structural parameters such as porosity, pore distribution and connectivity have great influence on the properties of mass transport in porous solids. In the present study, the effect of varying the workability of concrete in fresh state, produced through the use of additives, on pore structure and on the mechanical compressive strength of hardened concrete was assessed. The pore structure was analyzed with the aid of X-ray microtomography, and the results obtained were compared to the total pore volume calculated from data derived from helium and mercury pycnometry tests. A good approximation between the porosity values obtained through the two techniques was observed, and it was found that, regardless of concrete consistency, the samples from the surface of the specimens showed a percentage of pores higher than those taken from the more inner layers.

  5. Total energy cycle assessment of electric and conventional vehicles: an energy and environmental analysis. Volume 1: technical report

    Energy Technology Data Exchange (ETDEWEB)

    Cuenca, R.; Formento, J.; Gaines, L.; Marr, B.; Santini, D.; Wang, M. [Argonne National Lab., IL (United States); Adelman, S.; Kline, D.; Mark, J.; Ohi, J.; Rau, N. [National Renewable Energy Lab., Golden, CO (United States); Freeman, S.; Humphreys, K.; Placet, M. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-01-01

    This report compares the energy use, oil use and emissions of electric vehicles (EVs) with those of conventional, gasoline-powered vehicles (CVs) over the total life cycle of the vehicles. The various stages included in the vehicles` life cycles include vehicle manufacture, fuel production, and vehicle operation. Disposal is not included. An inventory of the air emissions associated with each stage of the life cycle is estimated. Water pollutants and solid wastes are reported for individual processes, but no comprehensive inventory is developed. Volume I contains the major results, a discussion of the conceptual framework of the study, and summaries of the vehicle, utility, fuel production, and manufacturing analyses. It also contains summaries of comments provided by external peer reviewers and brief responses to these comments.

  6. Total heart volume as a function of clinical and anthropometric parameters in a population of external beam radiation therapy patients

    Science.gov (United States)

    Nadège Ilembe Badouna, Audrey; Veres, Cristina; Haddy, Nadia; Bidault, François; Lefkopoulos, Dimitri; Chavaudra, Jean; Bridier, André; de Vathaire, Florent; Diallo, Ibrahima

    2012-01-01

    The aim of this paper was to determine anthropometric parameters leading to the least uncertain estimate of heart size when connecting a computational phantom to an external beam radiation therapy (EBRT) patient. From computed tomography images, we segmented the heart and calculated its total volume (THV) in a population of 270 EBRT patients of both sexes, aged 0.7-83 years. Our data were fitted using logistic growth functions. The patient age, height, weight, body mass index and body surface area (BSA) were used as explanatory variables. For both genders, good fits were obtained with both weight (R2 = 0.89 for males and 0.83 for females) and BSA (R2 = 0.90 for males and 0.84 for females). These results demonstrate that, among anthropometric parameters, weight plays an important role in predicting THV. These findings should be taken into account when assigning a computational phantom to a patient.

  7. The Association of Combined Total Kidney and Liver Volume with Pain and Gastrointestinal Symptoms in Patients with Later Stage Autosomal Dominant Polycystic Kidney Disease

    NARCIS (Netherlands)

    D'Agnolo, Hedwig M A; Casteleijn, Niek F; Gevers, Tom J G; de Fijter, Hans; van Gastel, Maartje D A; Messchendorp, Annemarie L; Peters, Dorien J M; Salih, Mahdi; Soonawala, Darius; Spithoven, Edwin M; Visser, Folkert W; Wetzels, Jack F M; Zietse, Robert; Gansevoort, Ron T; Drenth, Joost P H

    2017-01-01

    BACKGROUND: There is an ongoing debate if and how kidney and liver volume are associated with pain and gastrointestinal (GI) symptoms in autosomal dominant polycystic kidney disease (ADPKD) patients. Since both kidney and liver volume could interact, we investigated whether combined total kidney and

  8. Nanometer to Centimeter Scale Analysis and Modeling of Pore Structures

    Science.gov (United States)

    Wesolowski, D. J.; Anovitz, L.; Vlcek, L.; Rother, G.; Cole, D. R.

    2011-12-01

    The microstructure and evolution of pore space in rocks is a critically important factor controlling fluid flow. The size, distribution and connectivity of these confined geometries dictate how fluids including H2O and CO2, migrate into and through these micro- and nano-environments, wet and react with the solid. (Ultra)small-angle neutron scattering and autocorrelations derived from BSE imaging provide a method of quantifying pore structures in a statistically significant manner from the nanometer to the centimeter scale. Multifractal analysis provides additional constraints. These methods were used to characterize the pore features of a variety of potential CO2 geological storage formations and geothermal systems such as the shallow buried quartz arenites from the St. Peter Sandstone and the deeper Mt. Simon quartz arenite in Ohio as well as the Eau Claire shale and mudrocks from the Cranfield MS CO2 injection test and the normal temperature and high-temperature vapor-dominated parts of the Geysers geothermal system in California. For example, analyses of samples of St. Peter sandstone show total porosity correlates with changes in pores structure including pore size ratios, surface fractal dimensions, and lacunarity. These samples contain significant large-scale porosity, modified by quartz overgrowths, and neutron scattering results show significant sub-micron porosity, which may make up fifty percent or more of the total pore volume. While previous scattering data from sandstones suggest scattering is dominated by surface fractal behavior, our data are both fractal and pseudo-fractal. The scattering curves are composed of steps, modeled as polydispersed assemblages of pores with log-normal distributions. In some samples a surface-fractal overprint is present. There are also significant changes in the mono and multifractal dimensions of the pore structure as the pore fraction decreases. There are strong positive correlations between D(0) and image and total

  9. Genome-wide association study for semen volume and total number of sperm in Holstein-Friesian bulls.

    Science.gov (United States)

    Hering, D M; Oleński, K; Ruść, A; Kaminski, S

    2014-12-30

    In artificial insemination industry bulls producing high volume of semen with relatively high concentration of sperm are very desirable since they ensure stable production of commercial straws especially in case of top bulls. The aim of the study was to screen the entire bull genome to identify markers and candidate genes underlying semen volume (SV) and total number of sperm (TNS) in ejaculate produced by Holstein-Friesian bulls. Data on semen production were retrieved from records of AI center and included a population of 877 Holstein-Friesian bulls. Each bull was genotyped using the Illumina BovineSNP50 BeadChip. Genome-wide association analysis was performed with the use of GoldenHelix SVS7 software. An additive model for Linear Regression Analysis was used to estimate the effect of SNP marker for SV and TNS. After Bonferroni correction, 3 markers located on chromosome 22 reached the highest significance (rs41625599, rs41584616, rs42012507) for both traits. In the vicinity of these significant markers 3 genes are located (DCP1A, SFMBT1, TMEM110). Moreover, marker rs110109069 located on chromosome 25 was significantly associated with TNS and marker rs42438348 located on chromosome 10 has been found to be associated with SV. Some additional candidate genes were suggested to be potentially involved in analyzed traits (GALC, PRKCD, PHF7, TLR9, SPATA7). Identifying SNPs associated with the lower total number of sperm may be very useful for early recognition of a young sire as less suitable for effective semen production in artificial insemination centers.

  10. Determination of the optimal pore size for improved CO2 adsorption in activated carbon fibers.

    Science.gov (United States)

    Lee, Seul-Yi; Park, Soo-Jin

    2013-01-01

    Commercially available activated carbon fibers (ACFs) were modified further by a chemical activation method to obtain superior CO(2) adsorption capacity. The relationship between the pore structure of the modified ACF and the CO(2) adsorption behaviors was investigated. Chemical activation (with KOH at a fixed activation temperature of 900°C for 1h and various KOH/ACF weight ratios ranging from 1 to 4) of ACF increased the total pore volume and specific surface area to 1.124 cm(3)g(-1) (KOH/ACF weight ratio of 2) and 2318 m(2)g(-1) (KOH/ACF weight ratio of 4), respectively. Compared to ACF, the total pore volume and specific surface area were improved by factors of 2.5 and 2.3, respectively. Interestingly, the highest CO(2) adsorption capacity of 250 mg g(-1) at 298 K and 1 bar was observed at a KOH/ACF weight ratio of 3. The modified ACF had the narrowest microporosity ranging from 0.5 to 0.7 nm. Therefore, the increase in CO(2) adsorption capacity after chemical activation is closely related to the narrower pore size distribution rather than the total or micropore volume and specific surface area.

  11. A totally Eulerian Finite Volume solver for multi-material fluid flows: Enhanced Natural Interface Positioning (ENIP)

    CERN Document Server

    Loubère, Raphaël; Ghidaglia, Jean-Michel

    2010-01-01

    This work concerns the simulation of compressible multi-material fluid flows and follows the method FVCF-NIP described in the former paper Braeunig et al (Eur. J. Mech. B/Fluids, 2009). This Cell-centered Finite Volume method is totally Eulerian since the mesh is not moving and a sharp interface, separating two materials, evolves through the grid. A sliding boundary condition is enforced at the interface and mass, momentum and total energy are conserved. Although this former method performs well on 1D test cases, the interface reconstruction suffers of poor accuracy in conserving shapes for instance in linear advection. This situation leads to spurious instabilities of the interface. The method Enhanced-NIP presented in the present paper cures an inconsistency in the former NIP method that improves strikingly the results. It takes advantage of a more consistent description of the interface in the numerical scheme. Results for linear advection and compressible Euler equations for inviscid fluids are presented ...

  12. Pyrrolidine dithiocarbamate reduces the progression of total kidney volume and cyst enlargement in experimental polycystic kidney disease.

    Science.gov (United States)

    Ta, Michelle H T; Rao, Padmashree; Korgaonkar, Mayuresh; Foster, Sheryl F; Peduto, Anthony; Harris, David C H; Rangan, Gopala K

    2014-12-01

    Heterocyclic dithiocarbamates have anti-inflammatory and anti-proliferative effects in rodent models of chronic kidney disease. In this study, we tested the hypothesis that pyrrolidine dithiocarbamate (PDTC) reduces the progression of polycystic kidney disease (PKD). Male Lewis polycystic kidney (LPK) rats (an ortholog of Nek8/NPHP9) received intraperitoneal injections of either saline vehicle or PDTC (40 mg/kg once or twice daily) from postnatal weeks 4 until 11. By serial magnetic resonance imaging at weeks 5 and 10, the relative within-rat increase in total kidney volume and cyst volume were 1.3-fold (P = 0.01) and 1.4-fold (P < 0.01) greater, respectively, in LPK + Vehicle compared to the LPK + PDTC(40 mg/kg twice daily) group. At week 11 in LPK rats, PDTC attenuated the increase in kidney weight to body weight ratio by 25% (P < 0.01) and proteinuria by 66% (P < 0.05 vs. LPK + Vehicle) but did not improve renal dysfunction. By quantitative whole-slide image analysis, PDTC did not alter interstitial CD68+ cell accumulation, interstitial fibrosis, or renal cell proliferation in LPK rats at week 11. The phosphorylated form of the nuclear factor (NF)-κB subunit, p105, was increased in cystic epithelial cells of LPK rats, but was not altered by PDTC. Moreover, PDTC did not significantly alter nuclear expression of the p50 subunit or NF-κB (p65)-DNA binding. Kidney enlargement in LPK rats was resistant to chronic treatment with a proteasome inhibitor, bortezomib. In conclusion, PDTC reduced renal cystic enlargement and proteinuria but lacked anti-inflammatory effects in LPK rats.

  13. Three dimensional analysis of the pore space in fine-grained Boom Clay, using BIB-SEM (broad-ion beam scanning electron microscopy), combined with FIB (focused ion-beam) serial cross-sectioning, pore network modeling and Wood's metal injection

    Science.gov (United States)

    Hemes, Susanne; Klaver, Jop; Desbois, Guillaume; Urai, Janos

    2014-05-01

    The Boom Clay is, besides the Ypresian clays, one of the potential host rock materials for radioactive waste disposal in Belgium (Gens et al., 2003; Van Marcke & Laenen, 2005; Verhoef et al., 2011). To access parameters, which are relevant for the diffusion controlled transport of radionuclides in the material, such as porosity, pore connectivity and permeability, it is crucial to characterize the pore space at high resolution (nm-scale) and in 3D. Focused-ion-beam (FIB) serial cross-sectioning in combination with high resolution scanning electron microscopy (SEM), pore network modeling, Wood's metal injection and broad-ion-beam (BIB) milling, constitute a superior set of methods to characterize the 3D pore space in fine-grained, clayey materials, down to the nm-scale resolution. In the present study, we identified characteristic 3D pore space morphologies, determined the 3D volume porosity of the material and applied pore network extraction modeling (Dong and Blunt, 2009), to access the connectivity of the pore space and to discriminate between pore bodies and pore throats. Moreover, we used Wood's metal injection (WMI) in combination with BIB-SEM imaging to assess the pore connectivity at a larger scale and even higher resolution. The FIB-SEM results show a highly (~ 90 %) interconnected pore space in Boom Clay, down to the resolution of ~ 3E+03 nm³ (voxel-size), with a total volume porosity of ~ 20 %. Pore morphologies of large (> 5E+08 nm³), highly interconnected pores are complex, with high surface area to volume ratios (shape factors G ~ 0.01), whereas small (BIB-SEM, down to a resolution of ~ 50 nm² pixel-size, indicates an interconnected porosity fraction of ~ 80 %, of a total measured 2D porosity of ~ 20 %. Determining and distinguishing between pore bodies and pore throats enables us to compare 3D FIB-SEM pore-size distributions to 2D BIB-SEM data, as well as MIP data. Results show a good agreement between the 2D BIB-SEM and 3D FIB-SEM inferred pore

  14. Dilated pore of winer

    Directory of Open Access Journals (Sweden)

    Mittal R

    2002-01-01

    Full Text Available Two cases of dilated pore of Winer were observed. First case had single defined black papule with well defined margin, central pore and discharge of black powdery material from nose since 3 years. The second case had one 9mm, black well-defined papule with central pore discharging black powdery material on right forearm since 9 months and 9 similar smaller papules were seen on forearm and lower abdomen. Histopathologically both revealed greatly dilated infundibulum lined by acanthotic epidermis and atrophic subinfundibular hair structures thus confirming diagnosis of dilated pore of Winer

  15. Fractal classification and natural classification of coal pore structure based on migration of coal bed methane

    Institute of Scientific and Technical Information of China (English)

    FU Xuehai; QIN Yong; ZHANG Wanhong; WEI Chongtao; ZHOU Rongfu

    2005-01-01

    According to the data of 146 coal samples measured by mercury penetration, coal pores are classified into two levels of <65 nm diffusion pore and >65 nm seeping pore by fractal method based on the characteristics of diffusion, seepage of coal bed methane(CBM) and on the research results of specific pore volume and pore structure. The diffusion pores are further divided into three categories: <8 nm micropore, 8-20 nm transitional pore, and 20-65 nm minipore based on the relationship between increment of specific surface area and diameter of pores, while seepage pores are further divided into three categories: 65-325 nm mesopore,325-1000 nm transitional pore, and >1000 nm macropore based on the abrupt change in the increment of specific pore volume.

  16. Application analysis of solar total energy systems to the residential sector. Volume III, conceptual design. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1979-07-01

    The objective of the work described in this volume was to conceptualize suitable designs for solar total energy systems for the following residential market segments: single-family detached homes, single-family attached units (townhouses), low-rise apartments, and high-rise apartments. Conceptual designs for the total energy systems are based on parabolic trough collectors in conjunction with a 100 kWe organic Rankine cycle heat engine or a flat-plate, water-cooled photovoltaic array. The ORC-based systems are designed to operate as either independent (stand alone) systems that burn fossil fuel for backup electricity or as systems that purchase electricity from a utility grid for electrical backup. The ORC designs are classified as (1) a high temperature system designed to operate at 600/sup 0/F and (2) a low temperature system designed to operate at 300/sup 0/F. The 600/sup 0/F ORC system that purchases grid electricity as backup utilizes the thermal tracking principle and the 300/sup 0/F ORC system tracks the combined thermal and electrical loads. Reject heat from the condenser supplies thermal energy for heating and cooling. All of the ORC systems utilize fossil fuel boilers to supply backup thermal energy to both the primary (electrical generating) cycle and the secondary (thermal) cycle. Space heating is supplied by a central hot water (hydronic) system and a central absorption chiller supplies the space cooling loads. A central hot water system supplies domestic hot water. The photovoltaic system uses a central electrical vapor compression air conditioning system for space cooling, with space heating and domestic hot water provided by reject heat from the water-cooled array. All of the systems incorporate low temperature thermal storage (based on water as the storage medium) and lead--acid battery storage for electricity; in addition, the 600/sup 0/F ORC system uses a therminol-rock high temperature storage for the primary cycle. (WHK)

  17. Prognostic prediction across a gradient of total tumor volume in patients with hepatocellular carcinoma undergoing locoregional therapy

    Directory of Open Access Journals (Sweden)

    Lin Han C

    2010-12-01

    Full Text Available Abstract Background The size and number of tumors are important prognostic indicators for hepatocellular carcinoma (HCC. However, it is difficult to assess the prognosis for patients with a variable number and size of tumors. By combining these two factors, we investigated the role and prognostic accuracy of total tumor volume (TTV for HCC. Methods A total of 786 patients undergoing locoregional therapy (transarterial chemoembolization, percutaneous radiofrequency ablation and acetic acid or ethanol injection for HCC were prospectively evaluated. Results The mean and median TTV was 177 cm3 (range, 0.1-3,591 cm3 and 21 cm3, respectively. Of all, 38%, 29%, 15%, 7% and 11% of patients had TTV of 3, 10-50 cm3, 50-200 cm3, 200-500 cm3 and >500 cm3, respectively. TTV was significantly larger in patients with higher serum α-fetoprotein (AFP levels or with vascular invasion. The Child-Turcotte-Pugh score, performance status, vascular invasion, AFP level and TTV were significant independent prognostic predictors in the Cox proportional hazards model. After adjustment, patients with TTV 50-200 cm3 (relative risk [RR]: 1.74, p = 0.009, 200-500 cm3 (RR: 2.15, p = 0.006 and >500 cm3 (RR: 3.92, p 3. Conclusions TTV is a feasible prognostic predictor across a wide gradient and can be used to predict the mortality risk of HCC. Selecting appropriate cutoffs of TTV may help refine the design of cancer staging system and treatment planning. Future clinical trials of HCC may include this parameter for mortality risk stratification.

  18. Fort Hood Solar Total Energy Project. Volume II. Preliminary design. Part 1. System criteria and design description. Final report

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1979-01-01

    This volume documents the preliminary design developed for the Solar Total Energy System to be installed at Fort Hood, Texas. Current system, subsystem, and component designs are described and additional studies which support selection among significant design alternatives are presented. Overall system requirements which form the system design basis are presented. These include program objectives; performance and output load requirements; industrial, statutory, and regulatory standards; and site interface requirements. Material in this section will continue to be issued separately in the Systems Requirements Document and maintained current through revision throughout future phases of the project. Overall system design and detailed subsystem design descriptions are provided. Consideration of operation and maintenance is reflected in discussion of each subsystem design as well as in an integrated overall discussion. Included are the solar collector subsystem; the thermal storage subsystem, the power conversion sybsystem (including electrical generation and distribution); the heating/cooling and domestic hot water subsystems; overall instrumentation and control; and the STES building and physical plant. The design of several subsystems has progressed beyond the preliminary stage; descriptions for such subsystems are therefore provided in more detail than others to provide complete documentation of the work performed. In some cases, preliminary design parameters require specific verificaton in the definitive design phase and are identified in the text. Subsystem descriptions will continue to be issued and revised separately to maintain accuracy during future phases of the project. (WHK)

  19. Total Kidney Volume in Autosomal Dominant Polycystic Kidney Disease: A Biomarker of Disease Progression and Therapeutic Efficacy.

    Science.gov (United States)

    Alam, Ahsan; Dahl, Neera K; Lipschutz, Joshua H; Rossetti, Sandro; Smith, Patricia; Sapir, Daniel; Weinstein, Jordan; McFarlane, Philip; Bichet, Daniel G

    2015-10-01

    Autosomal dominant polycystic kidney disease (ADPKD) is the most common potentially life-threatening monogenic disorder in humans, characterized by progressive development and expansion of fluid-filled cysts in the kidneys and other organs. Ongoing cyst growth leads to progressive kidney enlargement, whereas kidney function remains stable for decades as a result of hyperfiltration and compensation by unaffected nephrons. Kidney function irreversibly declines only in the late stages of the disease, when most of the parenchyma is lost to cystic and fibrotic tissue and the remaining compensatory capacity is overwhelmed. Hence, conventional kidney function measures, such as glomerular filtration rate, do not adequately assess disease progression in ADPKD, especially in its early stages. Given the recent development of potential targeted therapies in ADPKD, it has become critically important to identify relevant biomarkers that can be used to determine the degree of disease progression and evaluate the effects of therapeutic interventions on the course of the disease. We review the current evidence to provide an informed perspective on whether total kidney volume (TKV) is a suitable biomarker for disease progression and whether TKV can be used as an efficacy end point in clinical trials. We conclude that because cystogenesis is the central factor leading to kidney enlargement, TKV appears to be an appropriate biomarker and is gaining wider acceptance. Several studies have identified TKV as a relevant imaging biomarker for monitoring and predicting disease progression and support its use as a prognostic end point in clinical trials.

  20. Peak oxygen uptake in relation to total heart volume discriminates heart failure patients from healthy volunteers and athletes

    Directory of Open Access Journals (Sweden)

    Buhre Torsten

    2010-12-01

    Full Text Available Abstract Background An early sign of heart failure (HF is a decreased cardiac reserve or inability to adequately increase cardiac output during exercise. Under normal circumstances maximal cardiac output is closely related to peak oxygen uptake (VO2peak which has previously been shown to be closely related to total heart volume (THV. Thus, the aim of this study was to derive a VO2peak/THV ratio and to test the hypothesis that this ratio can be used to distinguish patients with HF from healthy volunteers and endurance athletes. Thirty-one patients with HF of different etiologies were retrospectively included and 131 control subjects (60 healthy volunteers and 71 athletes were prospectively enrolled. Peak oxygen uptake was determined by maximal exercise test and THV was determined by cardiovascular magnetic resonance. The VO2peak/THV ratio was then derived and tested. Results Peak oxygen uptake was strongly correlated to THV (r2 = 0.74, p 2 = 0.0002, p = 0.95. The VO2peak/THV ratio differed significantly between control subjects and patients, even in patients with normal ejection fraction and after normalizing for hemoglobin levels (p 2peak/THV ratio was the only independent predictor of presence of HF (p Conclusions The VO2peak/THV ratio can be used to distinguish patients with clinically diagnosed HF from healthy volunteers and athletes, even in patients with preserved systolic left ventricular function and after normalizing for hemoglobin levels.

  1. Soil Pore Network Visualisation and Quantification using ImageJ

    DEFF Research Database (Denmark)

    Garbout, Amin; Pajor, Radoslaw; Otten, Wilfred

    Computed Tomography data. We used ImageJ to analyze images of pore geometries in soils generated by X-ray micro Computed Tomography. Soil samples were scanned at 30 μm resolution, and we produced replicated samples with different pore geometries by packing different sized soil aggregates at pre......-defined densities. First, scanned grayscale data of soil volumes were thresholded to separate solid and pore phases. Then, pore networks were extracted with the Skeletonize3D plug-in (Ignacio Arganda-Carreras), exploiting an ITK algorithm: binary thinning was used for finding the centerlines (”skeleton”) of pores...

  2. DIFFERENT PORE SIZE ALUMINA FOAMS AND STUDY OF THEIR MECHANICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    A. Hadi

    2015-03-01

    Full Text Available Recently, the open-cell ceramic foams have been extensively investigated due to special properties of these structures. They are excellent candidates for various applications such as molten metal and hot gas filtration, fabrication of metal matrix composites (MMC, heat exchangers and catalyst support. In this study to prepare high strength and high permeable foams, alumina suspensions with proper solid contents and suitable rheological behavior were used for different pore density foams. The properties of the prepared foams such as mean pore size, total porosity, mechanical strength and water permeability were characterized by using different techniques. A reduction in pore density caused an increase in total porosity from 78.5 % to 83 %. The compression strength of the samples was dependent on total porosity as well as properties of the suspension. Compression strengths of 1.77; 3.24 and 3.55 MPa were measured for 10, 17 and 27 ppi foams, respectively. Presence of high volume of permeable pores and good uniformity of the structure led to high permeable foams. The permeability measurement confirmed a rise in permeability rate with a decrease in pore density of the foams.

  3. Fingerprint pores extractor

    CSIR Research Space (South Africa)

    Mngenge, NA

    2012-11-01

    Full Text Available alone. Sweat pores have been less utilized in the past due to constraints imposed by fingerprint scanning devices and resolution standards. Recently, progress has been made on both scanning devices and resolution standards to support the use of pores...

  4. Pore size distribution mapping

    OpenAIRE

    Strange, John H.; J. Beau W. WEBBER; Schmidt, S.D.

    1996-01-01

    Pore size distribution mapping has been demonstrated using NMR cryoporometry\\ud in the presence of a magnetic field gradient, This novel method is extendable to 2D and 3D mapping. It offers a unique nondestructive method of obtaining full pore-size distributions in the range 3 to 100 nm at any point within a bulk sample. \\ud

  5. Pore structure in blended cement pastes

    DEFF Research Database (Denmark)

    Canut, Mariana Moreira Cavalcanti

    Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained...... supplement each other. Cement pastes (w/b=0.4) with and without slag and fly ash cured at two moisture (sealed and saturated) and temperature (20 and 55ºC) conditions were used to investigate the combined impact of SCMs addition and curing on the pore structure of pastes cured up to two years. Also...... volume and threshold pore size were found when comparing with plain cement paste at the same curing conditions. The porosity methods MIP, LTC and SEM have been shown to be suitable to characterise pore parameters of the pastes. MIP is a simple and fast method which covers a large range of pore sizes...

  6. Total energy cycle assessment of electric and conventional vehicles: an energy and environmental analysis. Volume 3: appendix E to technical report, comprehensive EVTECA results tables

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report compares the energy use, oil use and emissions of electric vehicles (EVs) with those of conventional, gasoline-powered vehicles (CVs) over the total life cycle of the vehicles. The various stages included in the vehicles` life cycles include vehicle manufacture, fuel production, and vehicle operation. Disposal is not included. An inventory of the air emissions associated with each stage of the life cycle is estimated. Water pollutants and solid wastes are reported for individual processes, but no comprehensive inventory is developed. Volume III presents the results of the total energy cycle model runs, which are summarized in Volume I.

  7. Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities

    Directory of Open Access Journals (Sweden)

    C. Marcolli

    2013-06-01

    deposition mechanism, but evident when assuming freezing in pores, because for homogeneous ice nucleation only small pore volumes are needed, while heterogeneous ice nucleation requires larger pore structures to contain at least one active site for immersion nucleation. Together, these pieces of evidence strongly suggest that ice nucleation within pores should be the prevailing freezing mechanism of clay minerals for RHw below water saturation. Extending the analysis to other types of ice nuclei shows that freezing in pores and cracks is probably the prevailing ice nucleation mechanism for glassy and volcanic ash aerosols at RHw below water saturation. Freezing of water in carbon nanotubes might be of significance for ice nucleation by soot aerosols. No case could be identified that gives clear evidence of ice nucleation by water vapor deposition on a solid surface. Inspection of ice nuclei with a close lattice match to ice, such as silver iodide or SnomaxTM, show that for high ice nucleation efficiency below water saturation the presence of impurities or cracks on the surface may be essential. Soluble impurities promote the formation of a liquid phase below water saturation in patches on the surface or as a complete surface layer that offers an environment for immersion freezing. If porous aerosol particles come in contact with semivolatile vapors, these will condense preferentially in pores before a coating on the surface of the particles is formed. A pore partially filled with condensed species attracts water at lower RHw than an empty pore, but the aqueous solution that forms in the pore will freeze at a higher RHi than pure water. The ice nucleation ability of pores completely filled with condensed organic species might be totally impeded. Pores might also be important for preactivation, the capability of a particle to nucleate ice at lower RHi in subsequent experiments when compared to the first initial ice nucleation event. Preactivation has often been explained by

  8. Velocities in Solar Pores

    Science.gov (United States)

    Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.

    1996-05-01

    We investigate the three dimensional structure of solar pores and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around pores with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in pores increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the pores appear near these boundaries. We analyze the vertical velocity structure in pores and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for pores. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.

  9. Minivoids in the Local Volume

    CERN Document Server

    Tikhonov, A V

    2006-01-01

    We consider a sphere of 7.5 Mpc radius, which contains 355 galaxies with accurately measured distances, to detect the nearest empty volumes. Using a simple void detection algorithm, we found six large (mini)voids in Aquila, Eridanus, Leo, Vela, Cepheus and Octans, each of more than 30 Mpc^3. Besides them, 24 middle-size "bubbles" of more than 5 Mpc^3 volume are detected, as well as 52 small "pores". The six largest minivoids occupy 58% of the considered volume. Addition of the bubbles and pores to them increases the total empty volume up to 75% and 81%, respectively. The detected local voids look like oblong potatoes with typical axial ratios b/a = 0.75 and c/a = 0.62 (in the triaxial ellipsoide approximation). Being arranged by the size of their volume, local voids follow power law of volumes-rankes dependence. A correlation Gamma-function of the Local Volume galaxies follows a power low with a formally calculated fractal dimension D = 1.5. We found that galaxies surrounding the local minivoids do not differ...

  10. Lower total and regional grey matter brain volumes in youth with perinatally-acquired HIV infection: Associations with HIV disease severity, substance use, and cognition.

    Science.gov (United States)

    Lewis-de Los Angeles, C Paula; Williams, Paige L; Huo, Yanling; Wang, Shirlene D; Uban, Kristina A; Herting, Megan M; Malee, Kathleen; Yogev, Ram; Csernansky, John G; Nichols, Sharon; Van Dyke, Russell B; Sowell, Elizabeth R; Wang, Lei

    2017-05-01

    Despite improved survival due to combination antiretroviral therapy (cART), youth with perinatally-acquired HIV (PHIV) show cognitive deficits and developmental delay at increased rates. HIV affects the brain during critical periods of development, and the brain may be a persistent reservoir for HIV due to suboptimal blood brain barrier penetration of cART. We conducted structural magnetic resonance imaging (sMRI) and cognitive testing in 40 PHIV youth (mean age=16.7years) recruited from the NIH Pediatric HIV/AIDS Cohort Study (PHACS) who are part of the first generation of PHIV youth surviving into adulthood. Historical and current HIV disease severity and substance use measures were also collected. Total and regional cortical grey matter brain volumes were compared to a group of 334 typically-developing, HIV-unexposed and uninfected youth (frequency-matched for age and sex) from the Pediatric Imaging, Neurocognition, and Genetics (PING) study (mean age=16.1years). PHIV youth had smaller (2.8-5.1%) total and regional grey matter volumes than HIV-unexposed and uninfected youth, with smallest volumes seen among PHIV youth with higher past peak viral load (VL) and recent unsuppressed VL. In PHIV youth, worse cognitive performance correlated with smaller volumes. This pattern of smaller grey matter volumes suggests that PHIV infection may influence brain development and underlie cognitive dysfunction seen in this population. Among PHIV youth, smaller volumes were also linked to substance use (alcohol use: 9.0-13.4%; marijuana use: 10.1-16.0%). In this study, collection of substance use information was limited to the PHIV cohort; future studies should also collect substance use information in controls to further address interactions between HIV and substance use on brain volume.

  11. Conservation agriculture effects on soil pore characteristics

    DEFF Research Database (Denmark)

    Munkholm, Lars Juhl; Abdollahi, Lotfollah

    of quantitative knowledge to support this statement. This study examines the long-term effects of crop rotations, residue management and tillage on soil pore characteristics of two sandy loam soils in Denmark. Results are reported from a split plot field experiment rotation as main plot factor and tillage...... air permeability and pore continuity index. Generally, residue input, especially when combined with direct drilling at the Foulum site, decreased bulk density and the volume of blocked air porosity, and increased air-filled porosity, volumetric water content, air permeability and gas diffusivity. Our...

  12. Pore size engineering applied to the design of separators for nickel-hydrogen cells and batteries

    Science.gov (United States)

    Abbey, K. M.; Britton, D. L.

    1983-01-01

    Pore size engineering in starved alkaline multiplate cells involves adopting techniques to widen the volume tolerance of individual cells. Separators with appropriate pore size distributions and wettability characteristics (capillary pressure considerations) to have wider volume tolerances and an ability to resist dimensional changes in the electrodes were designed. The separators studied for potential use in nickel-hydrogen cells consist of polymeric membranes as well as inorganic microporous mats. In addition to standard measurements, the resistance and distribution of electrolyte as a function of total cell electrolyte content were determined. New composite separators consisting of fibers, particles and/or binders deposited on Zircar cloth were developed in order to engineer the proper capillary pressure characteristics in the separator. These asymmetric separators were prepared from a variety of fibers, particles and binders. Previously announced in STAR as N83-24571

  13. Dynamic heart model for the mathematical cardiac torso (MCAT) phantom to represent the invariant total heart volume

    Science.gov (United States)

    Pretorius, P. H.; King, Michael A.; Tsui, Benjamin M.; LaCroix, Karen; Xia, Weishi

    1998-07-01

    This manuscript documents the alteration of the heart model of the MCAT phantom to better represent cardiac motion. The objective of the inclusion of motion was to develop a digital simulation of the heart such that the impact of cardiac motion on single photon emission computed tomography (SPECT) imaging could be assessed and methods of quantitating cardiac function could be investigated. The motion of the dynamic MCAT's heart is modeled by a 128 time frame volume curve. Eight time frames are averaged together to obtain a gated perfusion acquisition of 16 time frames and ensure motion within every time frame. The position of the MCAT heart was changed during contraction to rotate back and forth around the long axis through the center of the left ventricle (LV) using the end systolic time frame as turning point. Simple respiratory motion was also introduced by changing the orientation of the heart model in a 2 dimensional (2D) plane with every time frame. The averaging effect of respiratory motion in a specific time frame was modeled by randomly selecting multiple heart locations between two extreme orientations. Non-gated perfusion phantoms were also generated by averaging over all time frames. Maximal chamber volumes were selected to fit a profile of a normal healthy person. These volumes were changed during contraction of the ventricles such that the increase in volume in the atria compensated for the decrease in volume in the ventricles. The myocardium were modeled to represent shortening of muscle fibers during contraction with the base of the ventricles moving towards a static apex. The apical region was modeled with moderate wall thinning present while myocardial mass was conserved. To test the applicability of the dynamic heart model, myocardial wall thickening was measured using maximum counts and full width half maximum measurements, and compared with published trends. An analytical 3D projector, with attenuation and detector response included, was used

  14. Porosity and pore size distribution in a sedimentary rock: Implications for the distribution of chlorinated solvents

    Science.gov (United States)

    Shapiro, Allen M.; Evans, Chrsitopher E.; Hayes, Erin C.

    2017-01-01

    Characterizing properties of the rock matrix that control retention and release of chlorinated solvents is essential in evaluating the extent of contamination and the application of remediation technologies in fractured rock. Core samples from seven closely spaced boreholes in a mudstone subject to trichloroethene (TCE) contamination were analyzed using Mercury Intrusion Porosimetry to investigate porosity and pore size distribution as a function of mudstone characteristics, and depth and lateral extent in the aquifer; organic carbon content was also evaluated to identify the potential for adsorption. Porosity and retardation factor varied over two orders of magnitude, with the largest porosities and largest retardation factors associated with carbon-rich mudstone layers. Larger porosities were also measured in the shallow rock that has been subject to enhanced groundwater flow. Porosity also varied over more than an order of magnitude in spatially continuous mudstone layers. The analyses of the rock cores indicated that the largest pore diameters may be accessible to entry of the nonaqueous form of TCE. Although the porosity associated with the largest pore diameters is small (~ 0.1%), that volume of TCE can significantly affect the total TCE that is retained in the rock matrix. The dimensions of the largest pore diameters may also be accessible to microbes responsible for reductive dechlorination; however, the small percentage of the pore space that can accommodate microbes may limit the extent of reductive dechlorination in the rock matrix.

  15. Porosity and pore size distribution in a sedimentary rock: Implications for the distribution of chlorinated solvents.

    Science.gov (United States)

    Shapiro, Allen M; Evans, Christopher E; Hayes, Erin C

    2017-08-01

    Characterizing properties of the rock matrix that control retention and release of chlorinated solvents is essential in evaluating the extent of contamination and the application of remediation technologies in fractured rock. Core samples from seven closely spaced boreholes in a mudstone subject to trichloroethene (TCE) contamination were analyzed using Mercury Intrusion Porosimetry to investigate porosity and pore size distribution as a function of mudstone characteristics, and depth and lateral extent in the aquifer; organic carbon content was also evaluated to identify the potential for adsorption. Porosity and retardation factor varied over two orders of magnitude, with the largest porosities and largest retardation factors associated with carbon-rich mudstone layers. Larger porosities were also measured in the shallow rock that has been subject to enhanced groundwater flow. Porosity also varied over more than an order of magnitude in spatially continuous mudstone layers. The analyses of the rock cores indicated that the largest pore diameters may be accessible to entry of the nonaqueous form of TCE. Although the porosity associated with the largest pore diameters is small (~0.1%), that volume of TCE can significantly affect the total TCE that is retained in the rock matrix. The dimensions of the largest pore diameters may also be accessible to microbes responsible for reductive dechlorination; however, the small percentage of the pore space that can accommodate microbes may limit the extent of reductive dechlorination in the rock matrix. Published by Elsevier B.V.

  16. Properties of solar pores

    NARCIS (Netherlands)

    Sütterlin, Peter

    2001-01-01

    We present the results of an extensive investigation of the properties of solar pores. Spectra of all 4 Stokes parameters of several magnetic sensitive absorption lines as well as Stokes I only spectra of lines with low or vanishing Landéfactor have been observed. An inversion code based on the Leve

  17. Blood parasites, total plasma protein and packed cell volume of small wild mammals trapped in three mountain ranges of the Atlantic Forest in Southeastern Brazil.

    Science.gov (United States)

    Silva, M A M L; Ronconi, A; Cordeiro, N; Bossi, D E P; Bergallo, H G; Costa, M C C; Balieiro, J C C; Varzim, F L S B

    2007-08-01

    A study of blood parasites in small wild non-flying mammals was undertaken in three areas of the Atlantic Forest in Southeastern Brazil: Serra de Itatiaia, RJ, Serra da Bocaina, SP and Serra da Fartura, SP, from June 1999 to May 2001. A total of 450 animals (15 species) were captured in traps and it was observed in 15.5% of the blood smears the presence of Haemobartonella sp. and Babesia sp. in red blood cells. There was no statistically significant difference between parasited and non-parasited specimens regarding total plasma protein, packed cell volume and body weight, which strongly suggests that these specimens might be parasite reservoirs.

  18. Analysis of the total system life cycle cost for the Civilian Radioactive Waste Management Program. Volume 2. Supporting information

    Energy Technology Data Exchange (ETDEWEB)

    1986-04-01

    This report presents the detailed results and assumptions for the January 1986 Total System Life Cycle Cost (TSLCC) analysis. The report is composed of three sections: Section A lists the costing assumptions which have been made about the principal waste management system parameters; Section B presents the yearly flows of waste material between system facilities for the 8 logistics cases which were studied; and Section C presents the annual total system costs for each of the 32 TSLCC cases by major cost category.

  19. Contribution of phytoliths to total biogenic silica volumes in the tropical rivers of Malaysia and associated implications for the marine biogeochemical cycle

    Science.gov (United States)

    Zang, Jiaye; Liu, Sen; Liu, Yanguang; Ma, Yongxing; Ran, Xiangbin

    2016-09-01

    The contribution of phytoliths to total biogenic silica (BSi) volumes in rivers worldwide, and the associated implications for the biogeochemical cycle, require in-depth study. Based on samples from rivers in Peninsular Malaysia, this project investigated the source and characteristics of BSi found in Asian tropical rivers, as well as the process of reverse weathering taking place in these fluvial systems. Results indicated that BSi samples collected in sediments consisted of phytolith, diatom and sponge spicules. Phytoliths, predominantly of the elongate form, comprised 92.8%-98.3% of BSi in the Pahang River. Diatom BSi in this river consisted mainly of pennatae diatoms, but represented a relatively small proportion of the total BSi volume. However, diatom BSi (predominantly of the Centricae form) was more prevalent in the Pontian and Endau Rivers with shares of 68.8% and 79.3% of the total BSi volumes, respectively, than Pahang River. Carbon contents of the BSi particulates ranged from 1.85% to 10.8% with an average of 4.79%. These values are higher than those recorded in other studies to date, and indicate that BSi plays a major role in controlling permanent carbon burial. This study suggests that phytoliths from terrestrial plants are the primary constituents of BSi in the rivers of Peninsular Malaysia, and therefore represent a significant proportion of the coastal silica budget.

  20. Volume totalizers analysis of pipelines operated by TRANSPETRO National Operational Control Center; Analise de totalizadores de volume em oleodutos operados pelo Centro Nacional de Controle e Operacao da TRANSPETRO

    Energy Technology Data Exchange (ETDEWEB)

    Aramaki, Thiago Lessa; Montalvao, Antonio Filipe Falcao [Petrobras Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Marques, Thais Carrijo [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2012-07-01

    This paper aims to present the results and methodology in the analysis of differences in volume totals used in systems such as batch tracking and leak detection of pipelines operated by the National Center for Operational Control (CNCO) at TRANSPETRO. In order to optimize this type of analysis, software was developed to acquisition and processing of historical data using the methodology developed. The methodology developed takes into account the particularities encountered in systems operated by TRANSPETRO, more specifically, by CNCO. (author)

  1. Deltoid muscle volume affects clinical outcome of reverse total shoulder arthroplasty in patients with cuff tear arthropathy or irreparable cuff tears.

    Science.gov (United States)

    Yoon, Jong Pil; Seo, Anna; Kim, Jeong Jun; Lee, Chang-Hwa; Baek, Seung-Hun; Kim, Shin Yoon; Jeong, Eun Taek; Oh, Kyung-Soo; Chung, Seok Won

    2017-01-01

    We aimed to estimate the interrelation between preoperative deltoid muscle status by measuring the 3-dimensional deltoid muscle volume and postoperative functional outcomes after reverse total shoulder arthroplasty(RTSA). Thirty-five patients who underwent RTSA participated in this study. All patients underwent preoperative magnetic resonance imaging(MRI) as well as pre- and postoperative radiography and various functional outcome evaluations at least 1 year. The primary outcome parameter was set as age- and sex-matched Constant scores. The 3-dimensional deltoid muscle model was generated using a medical image processing software and in-house code, and the deltoid muscle volume was calculated automatically. Various clinical and radiographic factors comprising the deltoid muscle volume adjusted for body mass index(BMI) were analyzed, and their interrelation with the outcome parameters was appraised using a multivariate analysis. As a result, all practical consequences considerably improved following surgery(all pmuscle volume adjusted for BMI(p = 0.009), absence of a subscapularis complete tear (p = 0.040), and greater change in acromion-deltoid tuberosity distance(p = 0.013) were associated with higher matched Constant scores. Multivariate analysis indicated that the deltoid muscle volume was the single independent prognostic factor for practical consequences(p = 0.011). In conclusion, the preoperative deltoid muscle volume significantly affected the functional outcome following RTSA in patients with cuff tear arthropathy or irreparable cuff tears. Therefore, more attention should be paid to patients with severe atrophied deltoid muscle who are at a high risk for poor practical consequences subsequent to RTSA.

  2. Total mesorectal excision for rectal cancer in an unselected population: quality assessment in a low volume center.

    NARCIS (Netherlands)

    Ferenschild, F.T.; Dawson, I.; Wilt, J.H.W. de; Graaf, E.J. de; Groenendijk, R.P.R.; Tetteroo, G.W.

    2009-01-01

    OBJECTIVE: The aim of this study was to review the results and long-term outcome after total mesorectal excision (TME) for adenocarcinoma of the rectum in an unselected population in a community teaching hospital. MATERIALS AND METHODS: Between 1996 and 2003, 210 patients with rectal cancer were ide

  3. Personal best time, not anthropometry or training volume, is associated with total race time in a triple iron triathlon.

    Science.gov (United States)

    Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Senn, Oliver

    2011-04-01

    The purpose of this study was to investigate in 81 male recreational ultratriathletes (64 finishers and 17 nonfinishers) the relationship of anthropometry, prerace experience, and training with race outcome in a Triple Iron triathlon, using bi and multivariate analyses. In the bivariate analysis, the sum of 8 skinfolds (r = 0.38) and the sum of upper body skinfolds (r = 0.37) were positively related to total race time. None of the anthropometric variables was related to the swim or bike split. Circumference of upper arm (r = 0.42), percent body fat (r = 0.43), the sum of 8 skinfolds (r = 0.47), and the sum of upper body skinfolds (r = 0.45) were positively associated with the time in the run split. None of the training variables was related to total race time or split times. Personal best time in an Ironman triathlon (r = 0.59) and a Triple Iron triathlon (r = 0.82) were positively and highly significantly related to total race time. When all significant variables after bivariate analysis were included in a regression model, personal best time in a Triple Iron triathlon (p athletes with a background as an ultrarunner might have an advantage in successfully finishing a Triple Iron triathlon. However, ultrarunners should also have enough prerace experience in competing in Ironman and Triple Iron triathlons to successfully finish such a race.

  4. The pore space scramble

    Science.gov (United States)

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

    2015-04-01

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

  5. Comparison of bioimpedance spectroscopy and X-Ray micro-computed tomography for total fat volume measurement in mice.

    Science.gov (United States)

    Aubertin, Gaelle; Sayeh, Amira; Dillenseger, Jean-Philippe; Ayme-Dietrich, Estelle; Choquet, Philippe; Niederhoffer, Nathalie

    2017-01-01

    Obesity and the metabolic syndrome are two pathologies whose prevalence are in a constant increase. Evaluation of the total fat mass but also of the distribution between visceral and subcutaneous adipose tissue are important factors while assessing the pathophysiology of these two pathologies. Computed tomography (CT) and bioimpedance (BIS) are the translational methods the most frequently used in human beings as well as in rodent models in longitudinal studies on adiposity and obesity. Surprisingly, no direct comparison of micro-CT and BIS was reported yet in mice. Therefore, the present study was carried out to evaluate and compare the accuracy and the uncertainty of measurement of micro-CT and BIS in this species. The proportion of fat mass was measured with BIS, micro-CT and direct post-mortem tissue weight, and correlations between the data were established to evaluate the accuracy of the methods but also the uncertainty of BIS and micro-CT. There were significant correlations between weights of fat tissues on scale and proportion of total fat mass determined by BIS or micro-CT (r = 0.81 and 0.86 respectively) but both methods overestimated the total fat mass, especially in the smallest animals; overestimation of fat mass was amplified with BIS compared to micro-CT. In addition BIS and micro-CT were highly correlated (r = 0.94). Test-test reliability showed a greater variability of the BIS with respect to the micro-CT (coefficient of variation = 17.2 vs 5.6% respectively). Hence, as far as subtle differences between groups or changes within one group are awaited, micro-CT may appear as the most reliable method for determination of fat mass in mice. Micro-CT, unlike BIS, will also allow to qualitatively and quantitatively differentiate between subcutaneous and visceral adipose tissues, which is of major importance in studies on adiposity and its complications.

  6. Application analysis of solar total energy systems to the residential sector. Volume IV, market penetration. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1979-07-01

    This volume first describes the residential consumption of energy in each of the 11 STES regions by fuel type and end-use category. The current and projected costs and availability of fossil fuels and electricity for the STES regions are reported. Projections are made concerning residential building construction and the potential market for residential STES. The effects of STES ownership options, institutional constraints, and possible government actions on market penetration potential were considered. Capital costs for two types of STES were determined, those based on organic Rankine cycle (ORC) heat engines and those based on flat plate, water-cooled photovoltaic arrays. Both types of systems utilized parabolic trough collectors. The capital cost differential between conventional and STE systems was calculated on an incremental cost per dwelling unit for comparison with projected fuel savings in the market penetration analysis. The market penetration analysis was planned in two phases, a preliminary analysis of each of the geographical regions for each of the STE systems considered; and a final, more precise analysis of those regions and systems showing promise of significant market penetration. However, the preliminary analysis revealed no geographical regions in which any of the STES considered promised to be competitive with conventional energy systems using utility services at the prices projected for future energy supplies in the residential market. Because no promising situations were found, the analysis was directed toward an examination of the parameters involved in an effort to identify those factors which make a residential STES less attractive than similar systems in the commercial and industrial areas. Results are reported. (WHK)

  7. Pore scale heterogeneity in the mineral distribution and reactive surface area of rocks

    Science.gov (United States)

    Lai, P. E.; Krevor, S. C.

    2013-12-01

    There are long-standing challenges in characterizing reactive transport in porous media at scales larger than individual pores. This hampers the prediction of the field-scale impact of geochemical processes on fluid flow [1]. This is a source of uncertainty for CO2 injection, which results in a reactive fluid-rock system, particularly in carbonate rock reservoirs. A potential cause is the inability of the continuum approach to incorporate the impact of heterogeneity in pore-scale reaction rates. This results in part from pore-scale heterogeneities in surface area of reactive minerals [2,3]. In this study we have created μm resolution 3D images of 3 sandstone and 4 carbonate rocks using x-ray microtomography. Using in-house image processing techniques and auxiliary characterisation with thin section, electron microscope and spectroscopic techniques we quantified the surface area of each mineral phase in the x-ray CT images. This quantification was validated against N2 BET surface area and He porosity measurements of the imaged samples. Distributions in reactive surface area for each mineral phase were constructed by calculating surface areas in thousands of randomly selected subvolume images of the total sample, each normalized to the pore volume in that image. In all samples, there is little correlation between the reactive surface area fraction and the volumetric fraction of a mineral in a bulk rock. Berea sandstone was far less heterogeneous and has a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. In carbonates, heterogeneity is more complex and surface area must be characterized at multiple length scales for an accurate description of reactive transport. [1] Maher, Steefel, Depaolo and Vianni (2006) Geochimica et Cosmochimica Acta, 70, 337-363 [2] Landrot, Ajo-Franklin, Yang, Cabrini and Steefel (2012) Chemical Geology 318-319, 113-125 [3] Li, Peters and Celia (2007) American Journal of Science 307, 1146

  8. Fort Hood Solar Total Energy Project. Volume II. Preliminary design. Part 2. System performance and supporting studies. Final report

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1979-01-01

    The preliminary design developed for the Solar Total Energy System to be installed at Fort Hood, Texas, is presented. System performance analysis and evaluation are described. Feedback of completed performance analyses on current system design and operating philosophy is discussed. The basic computer simulation techniques and assumptions are described and the resulting energy displacement analysis is presented. Supporting technical studies are presented. These include health and safety and reliability assessments; solar collector component evaluation; weather analysis; and a review of selected trade studies which address significant design alternatives. Additional supporting studies which are generally specific to the installation site are reported. These include solar availability analysis; energy load measurements; environmental impact assessment; life cycle cost and economic analysis; heat transfer fluid testing; meteorological/solar station planning; and information dissemination. (WHK)

  9. Exercise order affects the total training volume and the ratings of perceived exertion in response to a super-set resistance training session

    Directory of Open Access Journals (Sweden)

    Balsamo S

    2012-02-01

    Full Text Available Sandor Balsamo1–3, Ramires Alsamir Tibana1,2,4, Dahan da Cunha Nascimento1,2, Gleyverton Landim de Farias1,2, Zeno Petruccelli1,2, Frederico dos Santos de Santana1,2, Otávio Vanni Martins1,2, Fernando de Aguiar1,2, Guilherme Borges Pereira4, Jéssica Cardoso de Souza4, Jonato Prestes41Department of Physical Education, Centro Universitário UNIEURO, Brasília, 2GEPEEFS (Resistance training and Health Research Group, Brasília/DF, 3Graduate Program in Medical Sciences, School of Medicine, Universidade de Brasília (UnB, Brasília, 4Graduation Program in Physical Education, Catholic University of Brasilia (UCB, Brasília/DF, BrazilAbstract: The super-set is a widely used resistance training method consisting of exercises for agonist and antagonist muscles with limited or no rest interval between them – for example, bench press followed by bent-over rows. In this sense, the aim of the present study was to compare the effects of different super-set exercise sequences on the total training volume. A secondary aim was to evaluate the ratings of perceived exertion and fatigue index in response to different exercise order. On separate testing days, twelve resistance-trained men, aged 23.0 ± 4.3 years, height 174.8 ± 6.75 cm, body mass 77.8 ± 13.27 kg, body fat 12.0% ± 4.7%, were submitted to a super-set method by using two different exercise orders: quadriceps (leg extension + hamstrings (leg curl (QH or hamstrings (leg curl + quadriceps (leg extension (HQ. Sessions consisted of three sets with a ten-repetition maximum load with 90 seconds rest between sets. Results revealed that the total training volume was higher for the HQ exercise order (P = 0.02 with lower perceived exertion than the inverse order (P = 0.04. These results suggest that HQ exercise order involving lower limbs may benefit practitioners interested in reaching a higher total training volume with lower ratings of perceived exertion compared with the leg extension plus leg curl

  10. Total energy cycle assessment of electric and conventional vehicles: an energy and environmental analysis. Volume 4: peer review comments on technical report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report compares the energy use, oil use and emissions of electric vehicles (EVs) with those of conventional, gasoline-powered vehicles (CVs) over the total life cycle of the vehicles. The various stages included in the vehicles` life cycles include vehicle manufacture, fuel production, and vehicle operation. Disposal is not included. An inventory of the air emissions associated with each stage of the life cycle is estimated. Water pollutants and solid wastes are reported for individual processes, but no comprehensive inventory is developed. Volume IV includes copies of all the external peer review comments on the report distributed for review in July 1997.

  11. Total energy cycle assessment of electric and conventional vehicles: an energy and environmental analysis. Volume 2: appendices A-D to technical report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report compares the energy use, oil use and emissions of electric vehicles (EVs) with those of conventional, gasoline- powered vehicles (CVs) over the total life cycle of the vehicles. The various stages included in the vehicles` life cycles include vehicle manufacture, fuel production, and vehicle operation. Disposal is not included. An inventory of the air emissions associated with each stage of the life cycle is estimated. Water pollutants and solid wastes are reported for individual processes, but no comprehensive inventory is developed. Volume II contains additional details on the vehicle, utility, and materials analyses and discusses several details of the methodology.

  12. Surface pore tension and adsorption characteristics of polluted sediment

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Most natural sediment particles have numerous pores and a complex surface texture which facilitates their adsorption of contaminants. Particle surface structure,therefore,is an important instrumental factor in the transport of contaminants,especially in water environments. This paper reports on the results of adsorption-desorption experiments to analyze polluted sediment surface pore tension characteristics performed on samples from the bottom of Guanting Reservoir. In our analysis,the Frenkel-Halsey-Hill(FHH) equation is applied to calculate the fractal dimensions of particles to quantify the surface roughness and pore tension characteristics. The results show that the surface fractal dimensions of sediment particle surfaces normally measure from 2.6 to 2.85. The volume of pores smaller than 10 nm changes significantly after being contaminated with pollutants and the fractal dimension decreases because the pores adsorb the contaminants.

  13. Measurements of pore-scale flow through apertures.

    Energy Technology Data Exchange (ETDEWEB)

    Chojnicki, Kirsten

    2017-09-01

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

  14. Fasting gall bladder volume and lithogenicity in relation to glucose tolerance, total and intra-abdominal fat masses in obese non-diabetic subjects

    DEFF Research Database (Denmark)

    Hendel, H W; Højgaard, L; Andersen, T

    1998-01-01

    OBJECTIVE: To investigate whether total body fat mass or fat distribution and associated metabolic disturbances in glucose and lipid metabolism influence the well known gallstone pathogenetic factors in obese subjects in order to explain why some obese subjects develop gallstones and some do not....... DESIGN: Cross sectional study of gallstone pathogenetic factors, body composition, fat distribution, glucose and lipid metabolism. SUBJECTS: 57 healthy overweight subjects (aged 26-64y, body mass index (BMI) 30-45 kg/m2). MEASUREMENTS: Total and intra-abdominal fat masses were measured by dual X......-ray absorptiometry and abdominal CT scanning, respectively. The lithogenic index was measured in aspirated bile. The gallbladder volume was determined by ultrasound and the gallbladder ejection fraction% by dynamic cholescintigraphy. Plasma cholecystokinin (CCK) concentrations during a meal were measured...

  15. Blood parasites, total plasma protein and packed cell volume of small wild mammals trapped in three mountain ranges of the Atlantic Forest in Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    MAML. Silva

    Full Text Available A study of blood parasites in small wild non-flying mammals was undertaken in three areas of the Atlantic Forest in Southeastern Brazil: Serra de Itatiaia, RJ, Serra da Bocaina, SP and Serra da Fartura, SP, from June 1999 to May 2001. A total of 450 animals (15 species were captured in traps and it was observed in 15.5% of the blood smears the presence of Haemobartonella sp. and Babesia sp. in red blood cells. There was no statistically significant difference between parasited and non-parasited specimens regarding total plasma protein, packed cell volume and body weight, which strongly suggests that these specimens might be parasite reservoirs.

  16. Fasting gall bladder volume and lithogenicity in relation to glucose tolerance, total and intra-abdominal fat masses in obese non-diabetic subjects

    DEFF Research Database (Denmark)

    Hendel, H W; Højgaard, L; Andersen, T

    1998-01-01

    OBJECTIVE: To investigate whether total body fat mass or fat distribution and associated metabolic disturbances in glucose and lipid metabolism influence the well known gallstone pathogenetic factors in obese subjects in order to explain why some obese subjects develop gallstones and some do not....... DESIGN: Cross sectional study of gallstone pathogenetic factors, body composition, fat distribution, glucose and lipid metabolism. SUBJECTS: 57 healthy overweight subjects (aged 26-64y, body mass index (BMI) 30-45 kg/m2). MEASUREMENTS: Total and intra-abdominal fat masses were measured by dual X...... with a specific radioimmunoassay. Insulin sensitivity was measured by the Minimal Model and glucose tolerance by an oral glucose tolerance test (OGTT). Serum lipid concentrations were measured by standard methods. RESULTS: The gallbladder volume in the fasting state increased with increasing intra-abdominal fat...

  17. Impact Total Psoas Volume on Short- and Long-Term Outcomes in Patients Undergoing Curative Resection for Pancreatic Adenocarcinoma: a New Tool to Assess Sarcopenia

    Science.gov (United States)

    Amini, Neda; Spolverato, Gaya; Gupta, Rohan; Margonis, Georgios A.; Kim, Yuhree; Wagner, Doris; Rezaee, Neda; Weiss, Matthew J.; Wolfgang, Christopher L.; Makary, Martin M.; Kamel, Ihab R.; Pawlik, Timothy M.

    2016-01-01

    Background While sarcopenia is typically defined using total psoas area (TPA), characterizing sarcopenia using only a single axial cross-sectional image may be inadequate. We sought to evaluate total psoas volume (TPV) as a new tool to define sarcopenia and compare patient outcomes relative to TPA and TPV. Method Sarcopenia was assessed in 763 patients who underwent pancreatectomy for pancreatic adenocarcinoma between 1996 and 2014. It was defined as the TPA and TPV in the lowest sex-specific quartile. The impact of sarcopenia defined by TPA and TPV on overall morbidity and mortality was assessed using multivariable analysis. Result Median TPA and TPV were both lower in women versus men (both Psarcopenia was not associated with higher risk of postoperative complications (OR 1.06; P=0.72), sarcopenia defined by TPV was associated with morbidity (OR 1.79; P=0.002). On multivariable analysis, TPV-sarcopenia remained independently associated with an increased risk of postoperative complications (OR 1.69; P=0.006), as well as long-term survival (HR 1.46; P=0.006). Conclusion The use of TPV to define sarcopenia was associated with both short- and long-term outcomes following resection of pancreatic cancer. Assessment of the entire volume of the psoas muscle (TPV) may be a better means to define sarcopenia rather than a single axial image. PMID:25925237

  18. Assessment of treatment response by total tumor volume and global apparent diffusion coefficient using diffusion-weighted MRI in patients with metastatic bone disease: a feasibility study.

    Directory of Open Access Journals (Sweden)

    Matthew D Blackledge

    Full Text Available We describe our semi-automatic segmentation of whole-body diffusion-weighted MRI (WBDWI using a Markov random field (MRF model to derive tumor total diffusion volume (tDV and associated global apparent diffusion coefficient (gADC; and demonstrate the feasibility of using these indices for assessing tumor burden and response to treatment in patients with bone metastases. WBDWI was performed on eleven patients diagnosed with bone metastases from breast and prostate cancers before and after anti-cancer therapies. Semi-automatic segmentation incorporating a MRF model was performed in all patients below the C4 vertebra by an experienced radiologist with over eight years of clinical experience in body DWI. Changes in tDV and gADC distributions were compared with overall response determined by all imaging, tumor markers and clinical findings at serial follow up. The segmentation technique was possible in all patients although erroneous volumes of interest were generated in one patient because of poor fat suppression in the pelvis, requiring manual correction. Responding patients showed a larger increase in gADC (median change = +0.18, range = -0.07 to +0.78 × 10(-3 mm2/s after treatment compared to non-responding patients (median change = -0.02, range = -0.10 to +0.05 × 10(-3 mm2/s, p = 0.05, Mann-Whitney test, whereas non-responding patients showed a significantly larger increase in tDV (median change = +26%, range = +3 to +284% compared to responding patients (median change = -50%, range = -85 to +27%, p = 0.02, Mann-Whitney test. Semi-automatic segmentation of WBDWI is feasible for metastatic bone disease in this pilot cohort of 11 patients, and could be used to quantify tumor total diffusion volume and median global ADC for assessing response to treatment.

  19. Variations in pore characteristics in high volatile bituminous coals: Implications for coal bed gas content

    Science.gov (United States)

    Mastalerz, Maria; Drobniak, A.; Strapoc, D.; Solano-Acosta, W.; Rupp, J.

    2008-01-01

    The Seelyville Coal Member of the Linton Formation (Pennsylvanian) in Indiana was studied to: 1) understand variations in pore characteristics within a coal seam at a single location and compare these variations with changes occurring between the same coal at different locations, 2) elaborate on the influence of mineral-matter and maceral composition on mesopore and micropore characteristics, and 3) discuss implications of these variations for coal bed gas content. The coal is high volatile bituminous rank with R0 ranging from 0.57% to 0.60%. BET specific surface areas (determined by nitrogen adsorption) of the coals samples studied range from 1.8 to 22.9??m2/g, BJH adsorption mesopore volumes from 0.0041 to 0.0339??cm3/g, and micropore volumes (determined by carbon dioxide adsorption) from 0.0315 to 0.0540??cm3/g. The coals that had the largest specific surface areas and largest mesopore volumes occur at the shallowest depths, whereas the smallest values for these two parameters occur in the deepest coals. Micropore volumes, in contrast, are not depth-dependent. In the coal samples examined for this study, mineral-matter content influenced both specific surface area as well as mesopore and micropore volumes. It is especially clear in the case of micropores, where an increase in mineral-matter content parallels the decrease of micropore volume of the coal. No obvious relationships were observed between the total vitrinite content and pore characteristics but, after splitting vitrinite into individual macerals, we see that collotelinite influences both meso- and micropore volume positively, whereas collodetrinite contributes to the reduction of mesopore and micropore volumes. There are large variations in gas content within a single coal at a single location. Because of this variability, the entire thickness of the coal must be desorbed in order to determine gas content reliably and to accurately calculate the level of gas saturation. ?? 2008 Elsevier B.V. All

  20. High total metabolic tumor volume in PET/CT predicts worse prognosis in diffuse large B cell lymphoma patients with bone marrow involvement in rituximab era.

    Science.gov (United States)

    Song, Moo-Kon; Yang, Deok-Hwan; Lee, Gyeong-Won; Lim, Sung-Nam; Shin, Seunghyeon; Pak, Kyoung June; Kwon, Seong Young; Shim, Hye Kyung; Choi, Bong-Hoi; Kim, In-Suk; Shin, Dong-Hoon; Kim, Seong-Geun; Oh, So-Yeon

    2016-03-01

    Bone marrow involvement (BMI) in diffuse large B cell lymphoma (DLBCL) was naively regarded as an adverse clinical factor. However, it has been unknown which factor would separate clinical outcomes in DLBCL patients with BMI. Recently, metabolic tumor volume (MTV) on positron emission tomography/computed tomography (PET/CT) was suggested to predict prognosis in several lymphoma types. Therefore, we investigated whether MTV would separate the outcomes in DLBCL patients with BMI. MTV on PET/CT was defined as an initial tumor burden as target lesion ≥ standard uptake value, 2.5 in 107 patients with BMI. Intramedullary (IM) MTV was defined as extent of BMI and total MTV was as whole tumor burden. 260.5 cm(3) and 601.2 cm(3) were ideal cut-off values for dividing high and low MTV status in the IM and total lymphoma lesions in Receiver Operating Curve analysis. High risk NCCN-IPI (phigh IM MTV status (phigh total MTV status (phigh risk NCCN-IPI (PFS, p=0.006; OS, p=0.013), concordant subtype (PFS, p=0.005; OS, p=0.007), and high total MTV status (PFS, p<0.001; OS, p<0.001) had independent clinical impacts. MTV had prognostic significances for survivals in DLBCL with BMI.

  1. Pore dynamics in lipid membranes

    Science.gov (United States)

    Gozen, I.; Dommersnes, P.

    2014-09-01

    Transient circular pores can open in plasma membrane of cells due to mechanical stress, and failure to repair such pores lead to cell death. Similar pores in the form of defects also exist among smectic membranes, such as in myelin sheaths or mitochondrial membranes. The formation and growth of membrane defects are associated with diseases, for example multiple sclerosis. A deeper understanding of membrane pore dynamics can provide a more refined picture of membrane integrity-related disease development, and possibly also treatment options and strategies. Pore dynamics is also of great importance regarding healthcare applications such as drug delivery, gene or as recently been implied, cancer therapy. The dynamics of pores significantly differ in stacks which are confined in 2D compared to those in cells or vesicles. In this short review, we will summarize the dynamics of different types of pores that can be observed in biological membranes, which include circular transient, fusion and hemi-fusion pores. We will dedicate a section to floral and fractal pores which were discovered a few years ago and have highly peculiar characteristics. Finally, we will discuss the repair mechanisms of large area pores in conjunction with the current cell membrane repair hypotheses.

  2. Reliable estimation of adsorption isotherm parameters using adequate pore size distribution

    Energy Technology Data Exchange (ETDEWEB)

    Husseinzadeh, Danial; Shahsavand, Akbar [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2015-05-15

    The equilibrium adsorption isotherm has a crucial effect on various characteristics of the solid adsorbent (e.g., pore volume, bulk density, surface area, pore geometry). A historical paradox exists in conventional estimation of adsorption isotherm parameters. Traditionally, the total amount of adsorb material (total adsorption isotherm) has been considered equivalent to the local adsorption isotherm. This assumption is only valid when the corresponding pore size or energy distribution (PSD or ED) of the porous adsorbent can be successfully represented with the Dirac delta function. In practice, the actual PSD (or ED) is far from such assumption, and the traditional method for prediction of local adsorption isotherm parameters leads to serious errors. Up to now, the powerful combination of inverse theory and linear regularization technique has drastically failed when used for extraction of PSD from real adsorption data. For this reason, all previous researches used synthetic data because they were not able to extract proper PSD from the measured total adsorption isotherm with unrealistic parameters of local adsorption isotherm. We propose a novel approach that can successfully provide the correct values of local adsorption isotherm parameters without any a priori and unrealistic assumptions. Two distinct methods are suggested and several illustrative (synthetic and real experimental) examples are presented to clearly demonstrate the effectiveness of the newly proposed methods on computing the correct values of local adsorption isotherm parameters. The so-called Iterative and Optima methods' impressive performances on extraction of correct PSD are validated using several experimental data sets.

  3. Soils, Pores, and NMR

    Science.gov (United States)

    Pohlmeier, Andreas; Haber-Pohlmeier, Sabina; Haber, Agnes; Sucre, Oscar; Stingaciu, Laura; Stapf, Siegfried; Blümich, Bernhard

    2010-05-01

    Within Cluster A, Partial Project A1, the pore space exploration by means of Nuclear Magnetic Resonance (NMR) plays a central role. NMR is especially convenient since it probes directly the state and dynamics of the substance of interest: water. First, NMR is applied as relaxometry, where the degree of saturation but also the pore geometry controls the NMR signature of natural porous systems. Examples are presented where soil samples from the Selhausen, Merzenhausen (silt loams), and Kaldenkirchen (sandy loam) test sites are investigated by means of Fast Field Cycling Relaxometry at different degrees of saturation. From the change of the relaxation time distributions with decreasing water content and by comparison with conventional water retention curves we conclude that the fraction of immobile water is characterized by T1 samples (Haber-Pohlmeier et al. 2010). Third, relaxometric information forms the basis of understanding magnetic resonance imaging (MRI) results. The general difficulty of imaging in soils are the inherent fast T2 relaxation times due to i) the small pore sizes, ii) presence of paramagnetic ions in the solid matrix, and iii) diffusion in internal gradients. The last point is important, since echo times can not set shorter than about 1ms for imaging purposes. The way out is either the usage of low fields for imaging in soils or special ultra-short pulse sequences, which do not create echoes. In this presentation we will give examples on conventional imaging of macropore fluxes in soil cores (Haber-Pohlmeier et al. 2010), and the combination with relaxometric imaging, as well as the advantages and drawbacks of low-field and ultra-fast pulse imaging. Also first results on the imaging of soil columns measured by SIP in Project A3 are given. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Waterflow Monitored by Tracer Transport in Natural Porous Media Using MRI." Vadose Zone J.: submitted. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Relaxation in a

  4. Effects of supersaturation on pore shape in solid

    Science.gov (United States)

    Wei, P. S.; Hsiao, S. Y.

    2017-02-01

    The shape of a pore resulting from a bubble entrapped by a solidification front with different supersaturation ratios is predicted in this work. Supersaturation ratio, representing the ratio between solute concentration and saturation solute concentration, determines nucleation of a bubble and development of the pore shape in the early stage. Pore formation and its shape in solid influence contemporary issues of biology, engineering, foods, geophysics and climate change, etc. This work extends and combines previous models accounting for realistic mass and momentum transport, and physico-chemical equilibrium of solute gas across the bubble cap to self-consistently determine shape of the bubble cap beyond the solidification front and the pore shape in solid. The study also deal with that pore formation can be resulted from three different mechanisms, depending on the directions and magnitude of solute gas transport across the bubble cap. Case 1 is subject to solute transport from the pore across the cap into the surrounding liquid in the early stage. Cases 2a and 2b indicate opposite direction of solute transport. In contrast to Case 2b, the effect of solute transport on solute gas pressure in the pore in Case 2a is stronger than that of pore volume expansionin the last stage. The results find that an increase in supersaturation ratio decreases pore radius and time for bubble entrapment in Case 1. The bubble cannot be entrapped in Case 2. The predicted pore shape in solid agrees with experimental data. Understanding, prediction and control of the growth of the pore shape have therefore been obtained.

  5. Pore structure and growth kinetics in carbon materials

    Energy Technology Data Exchange (ETDEWEB)

    Bose, S.

    1978-04-01

    Pore structure of glassy carbon (GC) and pyrolytic graphite (PG) have been investigated. GC is one of the most impervious of solids finding applications in prosthetic devices and fuel cells while PG is used extensively in the aerospace industry. One third of the microstructure of GC consists of closed pores inaccessible to fluids. The microstructure of this material has been characterized using x-ray diffraction (XRD) and high resolution electron microscopy. Small angle x-ray scattering (SAXS) has been used to measure the angstrom sized pores and to follow the evolution of pore surface area as a function of heat treatment temperature (HTT) and heat treatment time (HTt) at constant temperature. From these measurements an analysis of the surface area kinetics was made to find out if rate processes are involved and to locate graphitization occurring at pore surfaces. PG on the other hand has been found to have larger sized pores that comprise five percent of its volume. In addition to being closed these pores are oriented. Some pore models are proposed for PG and the existing scattering theory from oriented ellipsoids is modified to include the proposed shapes.

  6. Formation of spherical stomatocyte of high-genus vesicle under pore-size constraint

    CERN Document Server

    Noguchi, Hiroshi

    2016-01-01

    Nuclear pores have an approximately uniform distribution in the nuclear envelope of most living cells. Hence, the morphology of the nuclear envelope is a spherical stomatocyte with a high genus. We have investigated the morphology of high-genus vesicles under pore-size constraint using dynamically triangulated membrane simulations. Bending-energy minimization without volume or other constraints produces a circular-cage stomatocyte, where the pores are aligned in a circular line on an oblate inner bud. As the pore radius is reduced, the circular-pore alignment is more stabilized than a random pore distribution on a spherical bud. However, we have clarified the conditions for the formation of a spherical stomatocyte: a small reduced volume, osmotic pressure within the inner bud, and repulsion between the pores. When area-difference elasticity is taken into account, the formation of cylindrical or budded tubules from the stomatocyte and discoidal stomatocyte is found.

  7. Partitioning of star branched polymers into pores at three chromatography conditions.

    Science.gov (United States)

    Wang, Yongmei; Masur, Aaron; Zhu, Yutian; Ziebarth, Jesse

    2010-09-24

    The partitioning of star branched polymers into a slit pore at three different chromatography conditions, namely, size exclusion chromatography (SEC), liquid chromatography at the critical condition (LCCC), and liquid adsorption chromatography (LAC) have been investigated with lattice Monte Carlo simulations. Two different chain models are used: random walks (RW) that have no excluded volume interaction and self-avoiding walks (SAW) that have excluded volume interaction. The simulation data obtained for the two chain models are compared to illustrate the effect of excluded volume interactions on the partitioning of star branched polymers. The two most outstanding effects observed due to the introduction of excluded volume interactions are: (i) stars with a high number of arms can be excluded from the pore at condition corresponding to the LCCC of the linear polymers; (ii) the partition coefficient of stars in LAC mode is not dependent only on the total number of monomers on the chain. These effects illustrated by the current study should be taken into account when interpreting experimental chromatography data for branched polymers. Copyright 2010 Elsevier B.V. All rights reserved.

  8. Using X-Ray Computed Tomography in Pore Structure Characterization for a Berea Sandstone: Resolution Effect

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Sheng; Hu, Qinhong; Dultz, Stefan; Zhang, Ming

    2012-11-23

    X-raycomputedtomography (XCT) is a powerful tool for detecting the micro-scale porestructure and has been applied to many natural and synthetic porous media. However, due to the resolution limitations, either non-representative view of the sample or inaccurate results can be produced from the XCT image processing. In this paper, two XCT (micro-CT and CT with synchrotron radiation) with different resolutions of 12.7 μm and 0.35 μm, as well as mercury intrusion porosimetry (MIP) with a minimum detection limit of 3 nm, were used for Berea sandstone to investigate the effect of detecting resolution on the porestructure. Several key porestructure parameters, including porosity, pore size distribution, pore connectivity, surface area, hydraulic radius, and aspect ratio were analyzed in a manner of quantitative comparison between different resolutions of XCT and MIP. The low resolution XCT can capture the large-pore porosity, while overestimates the pore size and pore connectivity. The high resolution XCT is more accurate in describing the pore shape, porosity, pore size; however, it is not representative since narrower detecting pore size range and small volume represented. A representative element volume related to large-pore porosity and probably large-pore connectivity with diameter and height of 2.8 mm is obtained through scale effect analysis. Therefore, selecting an appropriate resolution should be a compromise between the pore size and the representative element volume for the specific property or process of interest.

  9. Volume Entropy

    CERN Document Server

    Astuti, Valerio; Rovelli, Carlo

    2016-01-01

    Building on a technical result by Brunnemann and Rideout on the spectrum of the Volume operator in Loop Quantum Gravity, we show that the dimension of the space of the quadrivalent states --with finite-volume individual nodes-- describing a region with total volume smaller than $V$, has \\emph{finite} dimension, bounded by $V \\log V$. This allows us to introduce the notion of "volume entropy": the von Neumann entropy associated to the measurement of volume.

  10. Gravity destabilized non-wetting phase invasion in macro-heterogeneous porous media: Near pore scale macro modified invasion percolation simulation of experiments

    Energy Technology Data Exchange (ETDEWEB)

    GLASS JR.,ROBERT J.; CONRAD,STEPHEN H.; YARRINGTON,LANE

    2000-03-08

    The authors reconceptualize macro modified invasion percolation (MMIP) at the near pore (NP) scale and apply it to simulate the non-wetting phase invasion experiments of Glass et al [in review] conducted in macro-heterogeneous porous media. For experiments where viscous forces were non-negligible, they redefine the total pore filling pressure to include viscous losses within the invading phase as well as the viscous influence to decrease randomness imposed by capillary forces at the front. NP-MMIP exhibits the complex invasion order seen experimentally with characteristic alternations between periods of gravity stabilized and destabilized invasion growth controlled by capillary barriers. The breaching of these barriers and subsequent pore scale fingering of the non-wetting phase is represented extremely well as is the saturation field evolution, and total volume invaded.

  11. Analysis of the total system life cycle cost for the Civilian Radioactive Waste Management Program: Volume 2, Supporting information. [Civilian Radioactive Waste Management Program

    Energy Technology Data Exchange (ETDEWEB)

    1987-06-01

    This report provides cost estimates for the fifth evaluation of the adequacy of the fee and is consistent with the program strategy and plans. The total-system cost for the reference cases in the improved-performance system is estimated at $32.1 to $38.2 billion (expressed in constant 1986 collars) over the entire life of the system, or $1.5 to $1.6 billion more than that of the authorized system (i.e., the system without an MRS facility). The current estimate of the total-system cost for the reference cases in the improved-performance system is $3.8 to $5.4 billion higher than the estimate for the same system in the 1986 TSLCC analysis. In the case with the maximum increase, nearly all of the higher cost is due to a $5.2-billion increase in the costs of development and evaluation (D and E); all other system costs are essentially unchanged. The cost difference between the improved-performance system and the authorized system is smaller than the difference estimated in last year's TSLCC analysis. Volume 2 presents the detailed results for the 1987 analysis of the total-system life cycle cost (TSLCC). It consists of four sections: Section A presents the yearly flows of waste between waste-management facilities for the 12 aggregate logistics cases that were studied; Section B presents the annual total-system costs for each of the 30 TSLCC cases by major cost category; Section C presents the annual costs for the disposal of 16,000 canisters of defense high-level waste (DHLW) by major cost category for each of the 30 TSLCC cases; and Section D presents a summary of the cost-allocation factors that were calculated to determine the defense waste share of the total-system costs.

  12. Evaluation of Optimal Pore Size of (3-Aminopropyltriethoxysilane Grafted MCM-41 for Improved CO2 Adsorption

    Directory of Open Access Journals (Sweden)

    Zhilin Liu

    2015-01-01

    Full Text Available An array of new MCM-41 with substantially larger average pore diameters was synthesized through adding 1,3,5-trimethylbenzene (TMB as the swelling agent to explore the effect of pore size on final adsorbent properties. The pore expanded MCM-41 was also grafted with (3-Aminopropyltriethoxysilane (APTES to determine the optimal pore size for CO2 adsorption. The pore-expanded mesoporous MCM-41s showed relatively less structural regularity but significant increments of pore diameter (4.64 to 7.50 nm; the fraction of mesopore volume also illustrated an increase. The adsorption heat values were correlated with the order of the adsorption capacities for pore expanded MCM-41s. After amine functionalization, the adsorption capacities and heat values showed a significant increase. APTES-grafted pore-expanded MCM-41s depicted a high potential for CO2 capture regardless of the major drawback of the high energy required for regeneration.

  13. Temperature induced pore fluid pressurization in geomaterials

    CERN Document Server

    Ghabezloo, Siavash

    2010-01-01

    The theoretical basis of the thermal response of the fluid-saturated porous materials in undrained condition is presented. It has been demonstrated that the thermal pressurization phenomenon is controlled by the discrepancy between the thermal expansion of the pore fluid and of the solid phase, the stress-dependency of the compressibility and the non-elastic volume changes of the porous material. For evaluation of the undrained thermo-poro-elastic properties of saturated porous materials in conventional triaxial cells, it is important to take into account the effect of the dead volume of the drainage system. A simple correction method is presented to correct the measured pore pressure change and also the measured volumetric strain during an undrained heating test. It is shown that the porosity of the tested material, its drained compressibility and the ratio of the volume of the drainage system to the one of the tested sample, are the key parameters which influence the most the error induced on the measuremen...

  14. Water retention, gas transport, and pore network complexity during short-term regeneration of soil structure

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Møldrup, Per; Schjønning, Per

    2013-01-01

    was done using water retention (pore size distribution), soil gas diffusivity, air permeability, and derived pore network complexity parameters. Significant decreases in bulk density (increased total porosity) and increases in pores > 100 1m was observed for incubated samples compared with SR samples....... The proportion of pores > 100 1m increased in order: smectite gas diffusivity, air permeability, and derived pore network indices was greater for incubated samples than SR. For illitic soils...... for convective air transport when analyzing pore network complexity. Overall, our results showed that short-term regeneration...

  15. High-resolution mapping of a genetic locus regulating preferential carbohydrate intake, total kilocalories, and food volume on mouse chromosome 17.

    Directory of Open Access Journals (Sweden)

    Rodrigo Gularte-Mérida

    Full Text Available The specific genes regulating the quantitative variation in macronutrient preference and food intake are virtually unknown. We fine mapped a previously identified mouse chromosome 17 region harboring quantitative trait loci (QTL with large effects on preferential macronutrient intake-carbohydrate (Mnic1, total kilcalories (Kcal2, and total food volume (Tfv1 using interval-specific strains. These loci were isolated in the [C57BL/6J.CAST/EiJ-17.1-(D17Mit19-D17Mit50; B6.CAST-17.1] strain, possessing a ∼ 40.1 Mb region of CAST DNA on the B6 genome. In a macronutrient selection paradigm, the B6.CAST-17.1 subcongenic mice eat 30% more calories from the carbohydrate-rich diet, ∼ 10% more total calories, and ∼ 9% more total food volume per body weight. In the current study, a cross between carbohydrate-preferring B6.CAST-17.1 and fat-preferring, inbred B6 mice was used to generate a subcongenic-derived F2 mapping population; genotypes were determined using a high-density, custom SNP panel. Genetic linkage analysis substantially reduced the 95% confidence interval for Mnic1 (encompassing Kcal2 and Tfv1 from 40.1 to 29.5 Mb and more precisely established its boundaries. Notably, no genetic linkage for self-selected fat intake was detected, underscoring the carbohydrate-specific effect of this locus. A second key finding was the separation of two energy balance QTLs: Mnic1/Kcal2/Tfv1 for food intake and a newly discovered locus regulating short term body weight gain. The Mnic1/Kcal2/Tfv1 QTL was further de-limited to 19.0 Mb, based on the absence of nutrient intake phenotypes in subcongenic HQ17IIa mice. Analyses of available sequence data and gene ontologies, along with comprehensive expression profiling in the hypothalamus of non-recombinant, cast/cast and b6/b6 F2 controls, focused our attention on candidates within the QTL interval. Zfp811, Zfp870, and Btnl6 showed differential expression and also contain stop codons, but have no known biology

  16. Distribution and relation of total bacteria, active bacteria, bacterivory, and volume of organic detritus in Atlantic continental shelf waters off Cape Hatteras NC, USA

    Science.gov (United States)

    Sherr, Evelyn B.; Sherr, Barry F.; Verity, Peter G.

    During the Ocean Margins Program, we obtained data on the abundances of bacterioplankton and heterotrophic flagellates, and on rates of bacterivory, across the mid-Atlantic continental shelf off Cape Hatteras, NC, during four spring and summer cruises from 1993 to 1996. Bacterial and grazing parameters were compared for inner, middle, and outer shelf regions. In 1996, we sampled during two seasons: early spring (March) and mid-summer (July), and in addition determined the fractions of in situ bacterioplankton that had visible nucleoids (NV cells), or that had highly active electron transport systems (ETS), i.e. that were positive for reduction of the fluorogenic formazan compound, 5 cyano-2,3 ditolyl tetrazolium chloride (CTC+ cells), as well as the volumetric concentration of organic detrital particles. Detrital volumes and abundances of bacterioplankton and of heterotrophic flagellates, varied by an order of magnitude, and decreased from inshore to offshore shelf regions. In 1996, bacterial abundances and percentages of CTC+ cells were higher across the shelf during the early spring bloom season (March) compared to the post-bloom season (July). In March 1996, percentages of bacterial cells with visible nucleoids varied between 20% and 70%, but showed little change across the shelf; while fractions of total bacteria with highly active ETS were lower and more variable (1-16% CTC+ cells), and on average were twice as high in the inner shelf region compared to the rest of the shelf. Percentages of CTC+ cells were also higher for particle-associated bacteria. There was a strong positive relationship between percent CTC+ cells and volume of organic detrital particles. However, % CTC+ cells and detrital volume were not consistently related to either bulk particulate organic carbon or chlorophyll. Bacterivory, assessed via rate of ingestion of fluorescently labeled bacteria, could remove 2-9% (4-18% accounting for motile cells) of total bacterial stocks per day. If

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

    Science.gov (United States)

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

    2016-06-01

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

  18. A pore water conductivity sensor

    NARCIS (Netherlands)

    Hilhorst, M.A.

    2001-01-01

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

  19. Ion transport across transmembrane pores

    NARCIS (Netherlands)

    Leontiadou, Hari; Mark, Alan E.; Marrink, Siewert-Jan

    2007-01-01

    To study the pore-mediated transport of ionic species across a lipid membrane, a series of molecular dynamics simulations have been performed of a dipalmitoyl-phosphatidyl-choline bilayer containing a preformed water pore in the presence of sodium and chloride ions. It is found that the stability of

  20. Size dependent pore size distribution of shales by gas physisorption

    Science.gov (United States)

    Roshan, Hamid; Andersen, Martin S.; Yu, Lu; Masoumi, Hossein; Arandian, Hamid

    2017-04-01

    Gas physisorption, in particular nitrogen adsorption-desorption, is a traditional technique for characterization of geomaterials including the organic rich shales. The low pressure nitrogen is used together with adsorption-desorption physical models to study the pore size distribution (PSD) and porosity of the porous samples. The samples are usually crushed to a certain fragment size to measure these properties however there is not yet a consistent standard size proposed for sample crushing. Crushing significantly increases the surface area of the fragments e.g. the created surface area is differentiated from that of pores using BET technique. In this study, we show that the smaller fragment sizes lead to higher cumulative pore volume and smaller pore diameters. It is also shown that some of the micro-pores are left unaccounted because of the correction of the external surface area. In order to illustrate this, the nitrogen physisorption is first conducted on the identical organic rich shale samples with different sizes: 20-25, 45-50 and 63-71 µm. We then show that such effects are not only a function of pore structure changes induced by crushing, but is linked to the inability of the physical models in differentiating between the external surface area (BET) and micro-pores for different crushing sizes at relatively low nitrogen pressure. We also discuss models currently used in nano-technology such as t-method to address this issue and their advantages and shortcoming for shale rock characterization.

  1. Microfiltration of distillery stillage: Influence of membrane pore size

    Directory of Open Access Journals (Sweden)

    Vasić Vesna M.

    2012-01-01

    Full Text Available Stillage is one of the most polluted waste products of the food industry. Beside large volume, the stillage contains high amount of suspended solids, high values of chemical oxygen demand and biological oxygen demand, so it should not be discharged in the nature before previous purification. In this work, three ceramic membranes for microfiltration with different pore sizes were tested for stillage purification in order to find the most suitable membrane for the filtration process. Ceramic membranes with a nominal pore size of 200 nm, 450 nm and 800 nm were used for filtration. The influence of pore size on permeate flux and removal efficiency was investigated. A membrane with the pore size of 200 nm showed the best filtration performance so it was chosen for the microfiltration process.

  2. Pore-scale supercritical CO2 dissolution and mass transfer under drainage conditions

    Science.gov (United States)

    Chang, Chun; Zhou, Quanlin; Oostrom, Mart; Kneafsey, Timothy J.; Mehta, Hardeep

    2017-02-01

    Recently, both core- and pore-scale imbibition experiments have shown non-equilibrium dissolution of supercritical CO2 (scCO2) and a prolonged depletion of residual scCO2. In this study, pore-scale scCO2 dissolution and mass transfer under drainage conditions were investigated using a two-dimensional heterogeneous micromodel and a novel fluorescent water dye with a sensitive pH range between 3.7 and 6.5. Drainage experiments were conducted at 9 MPa and 40 °C by injecting scCO2 into the sandstone-analogue pore network initially saturated by water without dissolved CO2 (dsCO2). During the experiments, time-lapse images of dye intensity, reflecting water pH, were obtained. These images show non-uniform pH in individual pores and pore clusters, with average pH levels gradually decreasing with time. Further analysis on selected pores and pore clusters shows that (1) rate-limited mass transfer prevails with slowly decreasing pH over time when the scCO2-water interface area is low with respect to the volume of water-filled pores and pore clusters, (2) fast scCO2 dissolution and phase equilibrium occurs when scCO2 bubbles invade into water-filled pores, significantly enhancing the area-to-volume ratio, and (3) a transition from rate-limited to diffusion-limited mass transfer occurs in a single pore when a medium area-to-volume ratio is prevalent. The analysis also shows that two fundamental processes - scCO2 dissolution at phase interfaces and diffusion of dsCO2 at the pore scale (10-100 μm) observed after scCO2 bubble invasion into water-filled pores without pore throat constraints - are relatively fast. The overall slow dissolution of scCO2 in the millimeter-scale micromodel can be attributed to the small area-to-volume ratios that represent pore-throat configurations and characteristics of phase interfaces. This finding is applicable for the behavior of dissolution at pore, core, and field scales when water-filled pores and pore clusters of varying size are surrounded

  3. Pore-scale supercritical CO2 dissolution and mass transfer under drainage conditions

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chun; Zhou, Quanlin; Oostrom, Mart; Kneafsey, Timothy J.; Mehta, Hardeep

    2017-02-01

    Abstract: Recently, both core- and pore-scale imbibition experiments have shown non-equilibrium dissolution of supercritical CO2 (scCO2) and a prolonged depletion of residual scCO2. In this study, pore-scale scCO2 dissolution and mass transfer under drainage conditions were investigated using a two-dimensional heterogeneous micromodel and a novel fluorescent water dye with a sensitive pH range between 3.7 and 6.5. Drainage experiments were conducted at 9 MPa and 40 °C by injecting scCO2 into the sandstone-analogue pore network initially saturated by water without dissolved CO2 (dsCO2). During the experiments, time-lapse images of dye intensity, reflecting water pH, were obtained. These images show non-uniform pH in individual pores and pore clusters, with average pH levels gradually decreasing with time. Further analysis on selected pores and pore clusters shows that (1) rate-limited mass transfer prevails with slowly decreasing pH over time when the scCO2-water interface area is low with respect to the volume of water-filled pores and pore clusters, (2) fast scCO2 dissolution and phase equilibrium occurs when scCO2 bubbles invade into water-filled pores, significantly enhancing the area-to-volume ratio, and (3) a transition from rate-limited to diffusion-limited mass transfer occurs in a single pore when a medium area-to-volume ratio is prevalent. The analysis also shows that two fundamental processes – scCO2 dissolution at phase interfaces and diffusion of dsCO2 at the pore scale (10-100 µm) observed after scCO2 bubble invasion into water-filled pores without pore throat constraints – are relatively fast. The overall slow dissolution of scCO2 in the millimeter-scale micromodel can be attributed to the small area-to-volume ratios that represent pore-throat configurations and characteristics of phase

  4. Improved analytic methods for coal surface area and pore size distribution determination using 77 K nitrogen adsorption experiment

    Institute of Scientific and Technical Information of China (English)

    Wang Gongda; Wang Kai; Ren Tingxiang

    2014-01-01

    77 K nitrogen adsorption was the most widely used technique for determining surface area and pore size distribution of coal. Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) model are com-monly used analytic methods for adsorption/desorption isotherm. A Chinese anthracite coal is tested in this study using an improved experimental method and adsorption isotherm analyzed by three adsorp-tion mechanisms at different relative pressure stages. The result shows that the micropore filling adsorp-tion predominates at the relative pressure stage from 6.8E?7 to 9E?3. Theoretically, BET and BJH model are not appropriate for analyzing coal samples which contain micropores. Two new analytic procedures for coal surface area and pore size distribution calculation are developed in this work. The results show that BET model underestimates surface area, and micropores smaller than 1.751 nm account for 35.5%of the total pore volume and 74.2%of the total surface area. The investigation of surface area and pore size distribution by incorporating the influence of micropore is significant for understanding adsorption mechanism of methane and carbon dioxide in coal.

  5. Influence of Software Tool and Methodological Aspects of Total Metabolic Tumor Volume Calculation on Baseline [18F]FDG PET to Predict Survival in Hodgkin Lymphoma.

    Directory of Open Access Journals (Sweden)

    Salim Kanoun

    Full Text Available To investigate the respective influence of software tool and total metabolic tumor volume (TMTV0 calculation method on prognostic stratification of baseline 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography ([18F]FDG-PET in newly diagnosed Hodgkin lymphoma (HL.59 patients with newly diagnosed HL were retrospectively included. [18F]FDG-PET was performed before any treatment. Four sets of TMTV0 were calculated with Beth Israel (BI software: based on an absolute threshold selecting voxel with standardized uptake value (SUV >2.5 (TMTV02.5, applying a per-lesion threshold of 41% of the SUV max (TMTV041 and using a per-patient adapted threshold based on SUV max of the liver (>125% and >140% of SUV max of the liver background; TMTV0125 and TMTV0140. TMTV041 was also determined with commercial software for comparison of software tools. ROC curves were used to determine the optimal threshold for each TMTV0 to predict treatment failure.Median follow-up was 39 months. There was an excellent correlation between TMTV041 determined with BI and with the commercial software (r = 0.96, p<0.0001. The median TMTV0 value for TMTV041, TMTV02.5, TMTV0125 and TMTV0140 were respectively 160 (used as reference, 210 ([28;154] p = 0.005, 183 ([-4;114] p = 0.06 and 143 ml ([-58;64] p = 0.9. The respective optimal TMTV0 threshold and area under curve (AUC for prediction of progression free survival (PFS were respectively: 313 ml and 0.70, 432 ml and 0.68, 450 ml and 0.68, 330 ml and 0.68. There was no significant difference between ROC curves. High TMTV0 value was predictive of poor PFS in all methodologies: 4-years PFS was 83% vs 42% (p = 0.006 for TMTV02.5, 83% vs 41% (p = 0.003 for TMTV041, 85% vs 40% (p<0.001 for TMTV0125 and 83% vs 42% (p = 0.004 for TMTV0140.In newly diagnosed HL, baseline metabolic tumor volume values were significantly influenced by the choice of the method used for determination of volume. However, no significant differences were found

  6. Effects of steam activation on the pore structure and surface chemistry of activated carbon derived from bamboo waste

    Science.gov (United States)

    Zhang, Yan-Juan; Xing, Zhen-Jiao; Duan, Zheng-Kang; Li, Meng; Wang, Yin

    2014-10-01

    The effects of steam activation on the pore structure evolution and surface chemistry of activated carbon (AC) obtained from bamboo waste were investigated. Nitrogen adsorption-desorption isotherms revealed that higher steam activation temperatures and/or times promoted the creation of new micropores and widened the existing micropores, consequently decreasing the surface area and total pore volume. Optimum conditions included an activation temperature of 850 °C, activation time of 120 min, and steam flush generated from deionized water of 0.2 cm3 min-1. Under these conditions, AC with a BET surface area of 1210 m2 g-1 and total pore volume of 0.542 cm-3 g-1was obtained. Changes in surface chemistry were determined through Boehm titration, pH measurement, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Results revealed the presence of a large number of basic groups on the surface of the pyrolyzed char and AC. Steam activation did not affect the species of oxygen-containing groups but changed the contents of these species when compared with pyrolyzed char. Scanning electron microscopy was used to observe the surface morphology of the products. AC obtained under optimum conditions showed a monolayer adsorption capacity of 330 mg g-1 for methylene blue (MB), which demonstrates its excellent potential for MB adsorption applications.

  7. Effects of steam activation on the pore structure and surface chemistry of activated carbon derived from bamboo waste

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan-Juan [School of Chemical Engineering, Xiangtan University, Xiangtan 411105 (China); Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 36102 (China); Xing, Zhen-Jiao [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 36102 (China); Duan, Zheng-Kang [School of Chemical Engineering, Xiangtan University, Xiangtan 411105 (China); Meng Li [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 36102 (China); Wang, Yin, E-mail: yinwang@iue.ac.cn [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 36102 (China)

    2014-10-01

    The effects of steam activation on the pore structure evolution and surface chemistry of activated carbon (AC) obtained from bamboo waste were investigated. Nitrogen adsorption–desorption isotherms revealed that higher steam activation temperatures and/or times promoted the creation of new micropores and widened the existing micropores, consequently decreasing the surface area and total pore volume. Optimum conditions included an activation temperature of 850 °C, activation time of 120 min, and steam flush generated from deionized water of 0.2 cm{sup 3} min{sup −1}. Under these conditions, AC with a BET surface area of 1210 m{sup 2} g{sup −1} and total pore volume of 0.542 cm{sup −3} g{sup −1}was obtained. Changes in surface chemistry were determined through Boehm titration, pH measurement, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Results revealed the presence of a large number of basic groups on the surface of the pyrolyzed char and AC. Steam activation did not affect the species of oxygen-containing groups but changed the contents of these species when compared with pyrolyzed char. Scanning electron microscopy was used to observe the surface morphology of the products. AC obtained under optimum conditions showed a monolayer adsorption capacity of 330 mg g{sup −1} for methylene blue (MB), which demonstrates its excellent potential for MB adsorption applications.

  8. Linear correlation between the number of olfactory sensory neurons expressing a given mouse odorant receptor gene and the total volume of the corresponding glomeruli in the olfactory bulb

    Science.gov (United States)

    Bressel, Olaf Christian; Khan, Mona

    2015-01-01

    ABSTRACT Chemosensory specificity in the main olfactory system of the mouse relies on the expression of ∼1,100 odorant receptor (OR) genes across millions of olfactory sensory neurons (OSNs) in the main olfactory epithelium (MOE), and on the coalescence of OSN axons into ∼3,600 glomeruli in the olfactory bulb. A traditional approach for visualizing OSNs and their axons consists of tagging an OR gene genetically with an axonal marker that is cotranslated with the OR by virtue of an internal ribosome entry site (IRES). Here we report full cell counts for 15 gene‐targeted strains of the OR‐IRES‐marker design coexpressing a fluorescent protein. These strains represent 11 targeted OR genes, a 1% sample of the OR gene repertoire. We took an empirical, “count every cell” strategy: we counted all fluorescent cell profiles with a nuclear profile within the cytoplasm, on all serial coronal sections under a confocal microscope, a total of 685,673 cells in 56 mice at postnatal day 21. We then applied a strain‐specific Abercrombie correction to these OSN counts in order to obtain a closer approximation of the true OSN numbers. We found a 17‐fold range in the average (corrected) OSN number across these 11 OR genes. In the same series of coronal sections, we then determined the total volume of the glomeruli (TGV) formed by coalescence of the fluorescent axons. We found a strong linear correlation between OSN number and TGV, suggesting that TGV can be used as a surrogate measurement for estimating OSN numbers in these gene‐targeted strains. J. Comp. Neurol. 524:199–209, 2016. © 2015 Wiley Periodicals, Inc. PMID:26100963

  9. The role of metabolic tumor volume and total lesion glycolysis on {sup 18}F-FDG PET/CT in the prognosis of epithelial ovarian cancer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Won; Cho, Arthur; Lee, Jae-Hoon; Yun, Mijin; Lee, Jong Doo; Kang, Won Jun [Yonsei University College of Medicine, Department of Nuclear Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul (Korea, Republic of); Kim, Young Tae [Yonsei University College of Medicine, Department of Obstetrics and Gynecology, 134 Shinchon-dong, Seodaemoon-gu, Seoul (Korea, Republic of)

    2014-10-15

    This study assessed the prognostic value of pre-operative 2-[{sup 18}F] fluoro-2-deoxy-D-glucose ({sup 18}F-FDG) positron emission tomography/computed tomography (PET/CT) volumetric parameters, including metabolic tumor volume (MTV) and total lesion glycolysis (TLG), in patients with epithelial ovarian cancer. A total of 175 patients with epithelial ovarian cancer who underwent {sup 18} F-FDG PET/CT and subsequent cytoreductive surgery were retrospectively enrolled. Maximum standardized uptake value (SUVmax) on {sup 18}F-FDG PET/CT was measured for all patients. Because nine patients showed low tumor-to-background uptake ratios, MTV and TLG were measured in 166 patients. Univariate and multivariate analyses were performed to evaluate the prognostic significance of SUVmax, MTV, TLG, and clinicopathological factors for disease progression-free survival. Disease progressed in 78 (44.6 %) of the 175 patients, and the 2-year disease progression-free survival rate was 57.5 %. Univariate analysis showed that tumor stage, histopathological type, presence of regional lymph node metastasis, residual tumor after cytoreductive surgery, pre-operative serum carbohydrate antigen 125 (CA125) level, SUVmax, MTV, and TLG were significant prognostic factors (p < 0.05). Among these variables, tumor stage (p = 0.0006) and TLG (p = 0.008) independently correlated with disease progression-free survival on multivariate analysis. The disease progression rate was only 2.3 % in stage I-II patients with low TLG (≤100.0), compared to 80.0 % in stage III-IV patients with high TLG (>100.0). Along with tumor stage, TLG is an independent prognostic factor for disease progression after cytoreductive surgery in patients with epithelial ovarian cancer. By combining tumor stage and TLG, one can further stratify the risk of disease progression for patients undergoing cytoreductive surgery. (orig.)

  10. Modelo de predição para o volume total de Quaruba (Vochysia inundata ducke via análise de fatores e regressão

    Directory of Open Access Journals (Sweden)

    Mário Diego Rocha Valente

    2011-04-01

    Full Text Available Neste trabalho propôs-se um método para a construção de um modelo de regressão para determinar o Volume de Madeira Total da espécie florestal (Vochysia inundata ducke Quaruba, em função de suas características (Diâmetro à Altura do Peito (DAP, Idade e Altura. O modelo foi determinado utilizando-se a técnica estatística multivariada de Análise de Fatores com do Método das Componentes Principais via Rotação Ortogonal do Tipo Varimax para Extração dos Fatores, procurando contornar o problema da Multicolinearidade. Por fim desenvolveu-se um modelo de Regressão Linear Simples com base nos Escores Fatoriais. O modelo determinado apresentou-se de fácil interpretação e utilização, usando-se um fator e proporcionando um bom ajuste (R² = 96 % aos dados e uma boa capacidade preditiva. Ele atendeu a todas as suposições teóricas para sua existência e utilização.

  11. Investigations into the free-volume changes within starch/plasticizer/nanoclay systems using Positron Annihilation Lifetime Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Huihua, E-mail: h.liu@federation.edu.au [School of Health Sciences, Federation University Australia, Ballarat, Vic (Australia); Chaudhary, Deeptangshu, E-mail: deepc@ers.com.au [ERS Environmental Risk Solutions PTY LTD, Perth, WA (Australia); Campbell, Colin, E-mail: colin.campbell@anu.edu.au [ARC Centre of Excellence for Antimatter-Matter Studies (CAMS), Research School of Physics and Engineering, Australian National University, Canberra (Australia); Roberts, Jason, E-mail: jxr107@physics.anu.edu.au [ARC Centre of Excellence for Antimatter-Matter Studies (CAMS), Research School of Physics and Engineering, Australian National University, Canberra (Australia); Buckman, Stephen, E-mail: stephen.buckman@anu.edu.au [ARC Centre of Excellence for Antimatter-Matter Studies (CAMS), Research School of Physics and Engineering, Australian National University, Canberra (Australia); Sullivan, James, E-mail: james.sullivan@anu.edu.au [ARC Centre of Excellence for Antimatter-Matter Studies (CAMS), Research School of Physics and Engineering, Australian National University, Canberra (Australia)

    2014-11-14

    The free-volume of a matrix is a fundamental parameter that relates to its molecular and bulk characteristics, such as crystalline change and glass transition behavior. In starch-based bionanocomposite, we investigated the effect of the addition of montmorillonite nanoclay (MMT) and food plasticizers (glycerol and sorbitol) on changes of molecular pore size (including pore volume and pore distribution) using the Positron Annihilation Lifetime Spectroscopy (PALS) method. The results demonstrated counter-intuitive impact of MMT on the total free-volume where the total free-volume increased within the polymeric matrix. When compared to the pure matrix free-volume, the addition of MMT also resulted in the appearance of a broader distribution of the void sizes. The plasticizers, on the other hand, apparently occupied the void spaces, and therefore decreased the free-volume of the matrix. Further, together with the small angle X-ray scattering (SAXS) analysis, we concluded that this is a result of interplay between the plasticizer-plasticizer interactions and the polymer–plasticizer interactions. For example, in the starch/glycerol/MMT system, the pore radii slightly decrease upon the increasing of glycerol amount (OG210 = O.27 nm and OG220 = 0.26 nm), but the relative weight did increase with the increasing glycerol concentration. However, increasing the sorbitol amount increased the pore size from 0.23 nm(OS210) to 0.28 nm(OS220). Furthermore, the addition MMT in the OS010 system, promote the emergence of a new dateable pore radius(0.90 nm), and the total weight significantly increased from 13.70 (OS010) to 19.5% (OS210). We suggest that the pore variation (size and distribution) due to the MMT and plasticizers are reflected in the polymer glass transition and crystallinity because ultimately, the, total free-volume is a reflection of level of interactions existing within the bulk of these nanocomposites. - Highlights: • PALS is applied to explore the

  12. Studying Pore Structure of Nonwovens with 3D Imaging and Modeling Permeability

    Science.gov (United States)

    Baradari, Mehdi Gholipour

    Nonwovens are classified as a porous material and pore structure is named as the most important and complex feature of them. Since pore structure is out of control during any nonwovens manufacturing processes, many attempts have been made to measure the major characteristics of a pore network including: pore size, pore volume, pore surface area and pore shape. Among all pore characteristics, pore size due to its significant influence on many nonwovens applications such as filtration is counted as the most significant one. Generally, experiment, theoretical modeling and image analysis are the most common methods to measure pore size of nonwovens. Normally, pores in nonwovens make many convergences and divergences along the length and for this reason, many pore diameters could be assigned for a media. Due to inefficiency of the aforementioned techniques to measure all these diameters, they are not precise enough to study pore structure. The initial objective of this research is obtaining information of the pore structure, especially pore sizes, by applying image analysis techniques to a 3D image of nonwovens obtained through 3D imaging techniques such as DVI and micro CT. This 3D structure of the nonwoven media will be transformed to a graph, employing skeletonization through AvizoRTM software. The obtained graph exhibits topology, shape and connectivity of the pore structure for the utilized nonwoven. In this graph, each node and link would be a representative for pores intersection and body of pore, respectively. Saving the information of this graph results to some matrices/vectors including nodes coordinated, connectivity and nodes thickness, which exhibits the pore size. Therefore, all the pore sizes available in the structure will be extracted through this method. As expected, the information obtained from pore network is very complex consisting many numbers, so analyse them would be very difficult. Therefore, it was tried to use the saved information to model

  13. Mangrove pore water exchange across a latitudinal gradient

    Science.gov (United States)

    Tait, Douglas R.; Maher, Damien T.; Macklin, Paul A.; Santos, Isaac R.

    2016-04-01

    We combined observations of the natural tracer radon (222Rn) with hydrodynamic models across a broad latitudinal gradient covering several climate zones to estimate pore water exchange rates in mangroves. Pore water exchange ranged from 2.1 to 35.5 cm d-1 from temperate to tropical regions and averaged 16.3 ± 5.1 cm d-1. If upscaled to the global weighted mangrove area, pore water exchange in mangroves would recirculate the entire volume of water overlying the continental shelf in less than 153 years. Although pore water exchange (recirculated seawater) and river discharge represent different pathways for water entering the coastal ocean, the estimated global mangrove pore water exchange would be equal to approximately one third of annual global river discharge to the ocean (3.84 × 1013 m3 yr-1). Because biogeochemical processes in mangroves are largely dependent on pore water exchange, these large exchange rates have major implications for coastal nutrient, carbon, and greenhouse gas cycling in tropical marine systems.

  14. Pore Scale Analysis of Oil Shale/Sands Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chen-Luh [Univ. of Utah, Salt Lake City, UT (United States); Miller, Jan [Univ. of Utah, Salt Lake City, UT (United States)

    2011-03-01

    There are important questions concerning the quality and volume of pore space that is created when oil shale is pyrolyzed for the purpose of producing shale oil. In this report, 1.9 cm diameter cores of Mahogany oil shale were pyrolyzed at different temperatures and heating rates. Detailed 3D imaging of core samples was done using multiscale X-ray computed tomography (CT) before and after pyrolysis to establish the pore structure. The pore structure of the unreacted material was not clear. Selected images of a core pyrolyzed at 400oC were obtained at voxel resolutions from 39 microns (Οm) to 60 nanometers (nm). Some of the pore space created during pyrolysis was clearly visible at these resolutions and it was possible to distinguish between the reaction products and the host shale rock. The pore structure deduced from the images was used in Lattice Boltzmann simulations to calculate the permeability in the pore space. The permeabilities of the pyrolyzed samples of the silicate-rich zone were on the order of millidarcies, while the permeabilities of the kerogen-rich zone after pyrolysis were very anisotropic and about four orders of magnitude higher.

  15. Synthesis and characterization of high-surface-area millimeter-sized silica beads with hierarchical multi-modal pore structure by the addition of agar

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yosep; Choi, Junhyun [Department of Mineral Resources and Energy Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 561–756 (Korea, Republic of); Tong, Meiping, E-mail: tongmeiping@iee.pku.edu.cn [The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871 (China); Kim, Hyunjung, E-mail: kshjkim@jbnu.ac.kr [Department of Mineral Resources and Energy Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 561–756 (Korea, Republic of)

    2014-04-01

    Millimeter-sized spherical silica foams (SSFs) with hierarchical multi-modal pore structure featuring high specific surface area and ordered mesoporous frameworks were successfully prepared using aqueous agar addition, foaming and drop-in-oil processes. The pore-related properties of the prepared spherical silica (SSs) and SSFs were systematically characterized by field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), small-angle X-ray diffraction (SAXRD), Hg intrusion porosimetry, and N{sub 2} adsorption–desorption isotherm measurements. Improvements in the BET surface area and total pore volume were observed at 504 m{sup 2} g{sup −1} and 5.45 cm{sup 3} g{sup −1}, respectively, after an agar addition and foaming process. Despite the increase in the BET surface area, the mesopore wall thickness and the pore size of the mesopores generated from the block copolymer with agar addition were unchanged based on the SAXRD, TEM, and BJH methods. The SSFs prepared in the present study were confirmed to have improved BET surface area and micropore volume through the agar loading, and to exhibit interconnected 3-dimensional network macropore structure leading to the enhancement of total porosity and BET surface area via the foaming process. - Highlights: • Millimeter-sized spherical silica foams (SSFs) are successfully prepared. • SSFs exhibit high BET surface area and ordered hierarchical pore structure. • Agar addition improves BET surface area and micropore volume of SSFs. • Foaming process generates interconnected 3-D network macropore structure of SSFs.

  16. Pore geometry as a control on rock strength

    Science.gov (United States)

    Bubeck, A.; Walker, R. J.; Healy, D.; Dobbs, M.; Holwell, D. A.

    2017-01-01

    The strength of rocks in the subsurface is critically important across the geosciences, with implications for fluid flow, mineralisation, seismicity, and the deep biosphere. Most studies of porous rock strength consider the scalar quantity of porosity, in which strength shows a broadly inverse relationship with total porosity, but pore shape is not explicitly defined. Here we use a combination of uniaxial compressive strength measurements of isotropic and anisotropic porous lava samples, and numerical modelling to consider the influence of pore shape on rock strength. Micro computed tomography (CT) shows that pores range from sub-spherical to elongate and flat ellipsoids. Samples that contain flat pores are weaker if compression is applied parallel to the short axis (i.e. across the minimum curvature), compared to compression applied parallel to the long axis (i.e. across the maximum curvature). Numerical models for elliptical pores show that compression applied across the minimum curvature results in relatively broad amplification of stress, compared to compression applied across the maximum curvature. Certain pore shapes may be relatively stable and remain open in the upper crust under a given remote stress field, while others are inherently weak. Quantifying the shape, orientations, and statistical distributions of pores is therefore a critical step in strength testing of rocks.

  17. A general approach to crystalline and monomodal pore size mesoporous materials

    National Research Council Canada - National Science Library

    Poyraz, Altug S; Kuo, Chung-Hao; Biswas, Sourav; King'ondu, Cecil K; Suib, Steven L

    2013-01-01

    Mesoporous oxides attract a great deal of interest in many fields, including energy, catalysis and separation, because of their tunable structural properties such as surface area, pore volume and size...

  18. ESTIMATIVA DO VOLUME TOTAL DE MADEIRA EM ESPÉCIES DE EUCALIPTO A PARTIR DE IMAGENS DE SATÉLITE LANDSAT

    Directory of Open Access Journals (Sweden)

    Elias Fernando Berra

    2012-01-01

    Full Text Available Models relating spectral answers with biophysical parameters aim estimate variables, such as wood volume, without the necessity of frequent field measurements. The objective was to develop models to estimatewood volume by Landsat 5 TM images, supported by regional forest inventory data. The image was georeferenced and converted to spectral reflectance. After, the images-index NDVI (Normalized Difference Vegetation Index and SR (Simple Ratio was generated. The reflectance values of both spectral bands (TM1, TM2, TM3 e TM4 and indices (NDVI and SR was related with the wood volume. The biggest correlation with volume was with the NDVI and SR indices. The variables selection was made by Stepwise method, which returned three regression models as significant to explain the variation in volume. Finally,the best fitted model was selected (volume = -830,95 + 46,05 × (SR + 107,47 × (TM2, which was applied on the Landsat image where the pixels had started to represent the estimated volume in m³/ha on the Eucalyptus sp. production units. This model, significant at 95 % confidence level, explains 68 % of the wood volume variation.

  19. Total target volume is a better predictor of whole brain dose from gamma stereotactic radiosurgery than the number, shape, or location of the lesions.

    Science.gov (United States)

    Narayanasamy, Ganesh; Smith, Adam; Van Meter, Emily; McGarry, Ronald; Molloy, Janelle A

    2013-09-01

    To assess the hypothesis that the volume of whole brain that receives a certain dose level is primarily dependent on the treated volume rather than on the number, shape, or location of the lesions. This would help a physician validate the suitability of GammaKnife(®) based stereotactic radiosurgery (GKSR) prior to treatment. Simulation studies were performed to establish the hypothesis for both oblong and spherical shaped lesions of various numbers and sizes. Forty patients who underwent GKSR [mean age of 54 years (range 7-80), mean number of lesions of 2.5 (range 1-6), and mean lesion volume of 4.4 cm(3) (range 0.02-22.2 cm(3))] were also studied retrospectively. Following recommendations of QUANTEC, the volume of brain irradiated by the 12 Gy (VB12) isodose line was measured and a power-law based relation is proposed here for estimating VB12 from the known tumor volume and the prescription dose. In the simulation study on oblong, spherical, and multiple lesions, the volume of brain irradiated by 50%, 10%, and 1% of maximum dose was found to have linear, linear, and exponentially increasing dependence on the volume of the treated region, respectively. In the retrospective study on 40 GKSR patients, a similar relationship was found to predict the brain dose with a Spearman correlation coefficient >0.9. In both the studies, the volume of brain irradiated by a certain dose level does not have a statistically significant relationship (p ≥ 0.05) with the number, shape, or position of the lesions. The measured VB12 agrees with calculation to within 1.7%. The results from the simulation and the retrospective clinical studies indicate that the volume of whole brain that receives a certain percentage of the maximum dose is primarily dependent on the treated volume and less on the number, shape, and location of the lesions.

  20. Software Image J to study soil pore distribution

    Directory of Open Access Journals (Sweden)

    Sabrina Passoni

    2014-04-01

    Full Text Available In the soil science, a direct method that allows the study of soil pore distribution is the bi-dimensional (2D digital image analysis. Such technique provides quantitative results of soil pore shape, number and size. The use of specific softwares for the treatment and processing of images allows a fast and efficient method to quantify the soil porous system. However, due to the high cost of commercial softwares, public ones can be an interesting alternative for soil structure analysis. The objective of this work was to evaluate the quality of data provided by the Image J software (public domain used to characterize the voids of two soils, characterized as Geric Ferralsol and Rhodic Ferralsol, from the southeast region of Brazil. The pore distribution analysis technique from impregnated soil blocks was utilized for this purpose. The 2D image acquisition was carried out by using a CCD camera coupled to a conventional optical microscope. After acquisition and treatment of images, they were processed and analyzed by the software Noesis Visilog 5.4® (chosen as the reference program and ImageJ. The parameters chosen to characterize the soil voids were: shape, number and pore size distribution. For both soils, the results obtained for the image total porosity (%, the total number of pores and the pore size distribution showed that the Image J is a suitable software to be applied in the characterization of the soil sample voids impregnated with resin.

  1. Pore-space distribution and transport properties of an andesitic intrusion

    Science.gov (United States)

    Jamtveit, Bjørn; Krotkiewski, Marcin; Kobchenko, Maya; Renard, Francois; Angheluta, Luiza

    2014-08-01

    The pore structure of magmatic rocks records processes operating during magma solidification and cooling. It has first order effects on the petrophysical properties of the magmatic rocks, and also influences mass transfer and mineral reactions during subsequent metamorphism or weathering. Here, the pore space characteristics of an andesitic sill intrusion were determined by multiscale resolution computed X-ray microtomography (μ-CT), and the 3D structure was used for transport modeling. Unaltered andesite has a power law distribution of pore volumes over a range of five orders of magnitude. The probability distribution function (PDF) scales with the inverse square of the pore volume (V), PDF∝V-2. This scaling behavior is attributed to the coalescence of pores at crystal-melt boundaries. Large pores are concentrated on the outer margins of amphibole and plagioclase phenocrystals. Incipient weathering of the andesite is associated with preferential growth of weathering products in the largest pores. This can be explained by a model in which diffusion of external components into the porous andesite is controlled by a random network of grain boundaries and/or microfractures. This network preferentially links the larger pores to the system boundaries and it is the major fluid transport pathway, confining incipient weathering into a small fraction of the rock volume only.

  2. Activated carbon from char obtained from vacuum pyrolysis of teak sawdust: pore structure development and characterization.

    Science.gov (United States)

    Ismadji, S; Sudaryanto, Y; Hartono, S B; Setiawan, L E K; Ayucitra, A

    2005-08-01

    The preparation of activated carbon from vacuum pyrolysis char of teak sawdust was studied and the results are presented in this paper. The effects of process variables such as temperature and activation time on the pore structure of activated carbons were studied. The activated carbon prepared from char obtained by vacuum pyrolysis has higher surface area and pore volume than that from atmospheric pyrolysis char. The BET surface area and pore volume of activated carbon prepared from vacuum pyrolysis char were 1150 m2/g and 0.43 cm3/g, respectively.

  3. The prognostic value of functional tumor volume and total lesion glycolysis in patients with colorectal cancer liver metastases undergoing {sup 90}Y selective internal radiation therapy plus chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Gulec, Seza A.; Suthar, Rekha R.; Barot, Tushar C. [Jackson North Medical Center, Florida International University College of Medicine, North Miami Beach, FL (United States); Pennington, Kenneth [Center for Cancer Care, Goshen, IN (United States)

    2011-07-15

    Functional tumor volume (FTV) and total lesion glycolysis (TLG) are measures of metabolic activity of tumors determined by fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT images. These parameters could potentially have clinical value in response to treatment evaluation and disease prognostication. The objectives of this study were to investigate the relationship between functional tumor parameters (FTV and TLG) and clinical outcomes in patients with colorectal cancer liver metastases (CRCLM) undergoing {sup 90}Y-resin microsphere selective internal radiation therapy (SIRT) (SIR-Spheres {sup registered}, Sirtex Medical Limited, Lane Cove, NSW, Australia). FDG PET/CT studies of 20 patients with unresectable CRCLM who underwent {sup 90}Y SIRT under a phase II clinical trial were analyzed. FTV and TLG were calculated using PET VCAR (GE Healthcare, Milwaukee, WI, USA) on pretreatment and 4-week posttreatment scans. The effects of pretreatment and posttreatment functional tumor activity on patient survival were evaluated using Kaplan-Meier survival curves. The median survival in the study group was 14.8 months (range 2.0-27.7 months). The median survival for patients with pretreatment FTV values of above and below 200 cc were 11.2 and 26.9 months, respectively (p < 0.05). The median survival for patients with 4-week posttreatment FTV values of above and below 30 cc were 10.9 and 26.9 months, respectively (p < 0.05). The median survival for patients with pretreatment TLG values of above and below 600 g were 11.2 and 26.9 months, respectively (p < 0.05). The median survival for patients with 4-week posttreatment TLG values of above and below 100 g were 10.9 and 26.9 months, respectively (p < 0.05). Pretreatment and posttreatment FTV and TLG showed very strong association with survival. These values can be useful quantitative criteria for patient selection and disease prognostication when {sup 90}Y SIRT is contemplated in patients with CRCLM. (orig.)

  4. Baseline Metabolic Tumor Volume and Total Lesion Glycolysis Are Associated With Survival Outcomes in Patients With Locally Advanced Pancreatic Cancer Receiving Stereotactic Body Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Dholakia, Avani S. [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Chaudhry, Muhammad; Leal, Jeffrey P. [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Chang, Daniel T. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Raman, Siva P. [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Hacker-Prietz, Amy [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Su, Zheng; Pai, Jonathan [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Oteiza, Katharine E.; Griffith, Mary E. [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Wahl, Richard L. [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Tryggestad, Erik [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Pawlik, Timothy [Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Laheru, Daniel A. [Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Wolfgang, Christopher L. [Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Koong, Albert C. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); and others

    2014-07-01

    Purpose: Although previous studies have demonstrated the prognostic value of positron emission tomography (PET) parameters in other malignancies, the role of PET in pancreatic cancer has yet to be well established. We analyzed the prognostic utility of PET for patients with locally advanced pancreatic cancer (LAPC) undergoing fractionated stereotactic body radiation therapy (SBRT). Materials and Methods: Thirty-two patients with LAPC in a prospective clinical trial received up to 3 doses of gemcitabine, followed by 33 Gy in 5 fractions of 6.6 Gy, using SBRT. All patients received a baseline PET scan prior to SBRT (pre-SBRT PET). Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum and peak standardized uptake values (SUV{sub max} and SUV{sub peak}) on pre-SBRT PET scans were calculated using custom-designed software. Disease was measured at a threshold based on the liver SUV, using the equation Liver{sub mean} + [2 × Liver{sub sd}]. Median values of PET parameters were used as cutoffs when assessing their prognostic potential through Cox regression analyses. Results: Of the 32 patients, the majority were male (n=19, 59%), 65 years or older (n=21, 66%), and had tumors located in the pancreatic head (n=27, 84%). Twenty-seven patients (84%) received induction gemcitabine prior to SBRT. Median overall survival for the entire cohort was 18.8 months (95% confidence interval [CI], 15.7-22.0). An MTV of 26.8 cm{sup 3} or greater (hazard ratio [HR] 4.46, 95% CI 1.64-5.88, P<.003) and TLG of 70.9 or greater (HR 3.08, 95% CI 1.18-8.02, P<.021) on pre-SBRT PET scan were associated with inferior overall survival on univariate analysis. Both pre-SBRT MTV (HR 5.13, 95% CI 1.19-22.21, P=.029) and TLG (HR 3.34, 95% CI 1.07-10.48, P=.038) remained independently associated with overall survival in separate multivariate analyses. Conclusions: Pre-SBRT MTV and TLG are potential predictive factors for overall survival in patients with LAPC and may assist in

  5. STUDY PORE CHARACTERIZATION OF γ-ALUMINA – ACTIVATED CARBON COMPOSITE MADE OF CASSAVA PEELS (Manihot esculenta Cranz

    Directory of Open Access Journals (Sweden)

    Hartini Hartini

    2015-12-01

    Full Text Available A composite of γ-alumina and activated carbon made of cassava peels was studied in terms of its pore structures and its properties. The objective of this study was to determine the interaction and structure, as well as the character and pore size of γ-alumina – activated carbon composite. Carbon made of cassava peels was activated by H2SO4 and its activities were tested according to the Indonesian Industrial Standards (SII. The addition of activated carbon into γ-alumina made in variations of 10, 20, 30, 40 and 50 % w/w, of the total weight of 10 grams. The composite of γ-alumina - activated carbon was characterized by FTIR, SAA (Surface Area Analyzer, XRD, and determination of Hysteresis Loop composites. The greater addition of activated carbon to γ-alumina causes intermolecular interactions between –O-H groups form rehydrated hydrogen bonds in the composite is greater. The structure of γ-alumina in the composites remain intact although the percentage of activated carbon in composite is large. The total pore volume and surface area using the BET method of the composite decreases with increasing activated carbon percentage. The greater addition of activated carbon to γ-alumina causes size of mesoporous composites decreased with the characteristic of a composite formed is closer to the activated carbon.

  6. Effect of prenatal loud music and noise on total number of neurons and glia, neuronal nuclear area and volume of chick brainstem auditory nuclei, field L and hippocampus: a stereological investigation.

    Science.gov (United States)

    Sanyal, Tania; Palanisamy, Pradeep; Nag, T C; Roy, T S; Wadhwa, Shashi

    2013-06-01

    The present study explores whether prenatal patterned and unpatterned sound of high sound pressure level (110 dB) has any differential effect on the morphology of brainstem auditory nuclei, field L (auditory cortex analog) and hippocampus in chicks (Gallus domesticus). The total number of neurons and glia, mean neuronal nuclear area and total volume of the brainstem auditory nuclei, field L and hippocampus of post-hatch day 1 chicks were determined in serial, cresyl violet-stained sections, using stereology software. All regions studied showed a significantly increased total volume with increase in total neuron number and mean neuronal nuclear area in the patterned music stimulated group as compared to control. Contrastingly the unpatterned noise stimulated group showed an attenuated volume with reduction in the total neuron number. The mean neuronal nuclear area was significantly reduced in the auditory nuclei and hippocampus but increased in the field L. Glial cell number was significantly increased in both experimental groups, being highest in the noise group. The brainstem auditory nuclei and field L showed an increase in glia to neuron ratio in the experimental groups as compared to control. In the hippocampus the ratio remained unaltered between control and music groups, but was higher in the noise group. It is thus evident that though the sound pressure level in both experimental groups was the same there were differential changes in the morphological parameters of the brain regions studied, indicating that the characteristics of the sound had a role in mediating these effects.

  7. Pore evolution in interstellar ice analogues: simulating the effects of temperature increase

    CERN Document Server

    Cazaux, S; Linnartz, H; Tielens, A G G M

    2014-01-01

    Context. The level of porosity of interstellar ices - largely comprised of amorphous solid water (ASW) - contains clues on the trapping capacity of other volatile species and determines the surface accessibility that is needed for solid state reactions to take place. Aims. Our goal is to simulate the growth of amorphous water ice at low temperature (10 K) and to characterize the evolution of the porosity (and the specific surface area) as a function of temperature (from 10 to 120 K). Methods. Kinetic Monte Carlo simulations are used to mimic the formation and the thermal evolution of pores in amorphous water ice. We follow the accretion of gas-phase water molecules as well as their migration on surfaces with different grid sizes, both at the top growing layer and within the bulk. Results. We show that the porosity characteristics change substantially in water ice as the temperature increases. The total surface of the pores decreases strongly while the total volume decreases only slightly for higher temperatur...

  8. On the predictivity of pore-scale simulations: Estimating uncertainties with multilevel Monte Carlo

    Science.gov (United States)

    Icardi, Matteo; Boccardo, Gianluca; Tempone, Raúl

    2016-09-01

    A fast method with tunable accuracy is proposed to estimate errors and uncertainties in pore-scale and Digital Rock Physics (DRP) problems. The overall predictivity of these studies can be, in fact, hindered by many factors including sample heterogeneity, computational and imaging limitations, model inadequacy and not perfectly known physical parameters. The typical objective of pore-scale studies is the estimation of macroscopic effective parameters such as permeability, effective diffusivity and hydrodynamic dispersion. However, these are often non-deterministic quantities (i.e., results obtained for specific pore-scale sample and setup are not totally reproducible by another "equivalent" sample and setup). The stochastic nature can arise due to the multi-scale heterogeneity, the computational and experimental limitations in considering large samples, and the complexity of the physical models. These approximations, in fact, introduce an error that, being dependent on a large number of complex factors, can be modeled as random. We propose a general simulation tool, based on multilevel Monte Carlo, that can reduce drastically the computational cost needed for computing accurate statistics of effective parameters and other quantities of interest, under any of these random errors. This is, to our knowledge, the first attempt to include Uncertainty Quantification (UQ) in pore-scale physics and simulation. The method can also provide estimates of the discretization error and it is tested on three-dimensional transport problems in heterogeneous materials, where the sampling procedure is done by generation algorithms able to reproduce realistic consolidated and unconsolidated random sphere and ellipsoid packings and arrangements. A totally automatic workflow is developed in an open-source code [1], that include rigid body physics and random packing algorithms, unstructured mesh discretization, finite volume solvers, extrapolation and post-processing techniques. The

  9. On the predictivity of pore-scale simulations: estimating uncertainties with multilevel Monte Carlo

    KAUST Repository

    Icardi, Matteo

    2016-02-08

    A fast method with tunable accuracy is proposed to estimate errors and uncertainties in pore-scale and Digital Rock Physics (DRP) problems. The overall predictivity of these studies can be, in fact, hindered by many factors including sample heterogeneity, computational and imaging limitations, model inadequacy and not perfectly known physical parameters. The typical objective of pore-scale studies is the estimation of macroscopic effective parameters such as permeability, effective diffusivity and hydrodynamic dispersion. However, these are often non-deterministic quantities (i.e., results obtained for specific pore-scale sample and setup are not totally reproducible by another “equivalent” sample and setup). The stochastic nature can arise due to the multi-scale heterogeneity, the computational and experimental limitations in considering large samples, and the complexity of the physical models. These approximations, in fact, introduce an error that, being dependent on a large number of complex factors, can be modeled as random. We propose a general simulation tool, based on multilevel Monte Carlo, that can reduce drastically the computational cost needed for computing accurate statistics of effective parameters and other quantities of interest, under any of these random errors. This is, to our knowledge, the first attempt to include Uncertainty Quantification (UQ) in pore-scale physics and simulation. The method can also provide estimates of the discretization error and it is tested on three-dimensional transport problems in heterogeneous materials, where the sampling procedure is done by generation algorithms able to reproduce realistic consolidated and unconsolidated random sphere and ellipsoid packings and arrangements. A totally automatic workflow is developed in an open-source code [2015. https://bitbucket.org/micardi/porescalemc.], that include rigid body physics and random packing algorithms, unstructured mesh discretization, finite volume solvers

  10. Total and regional brain volumes in a population-based normative sample from 4 to 18 years: the NIH MRI Study of Normal Brain Development.

    Science.gov (United States)

    2012-01-01

    Using a population-based sampling strategy, the National Institutes of Health (NIH) Magnetic Resonance Imaging Study of Normal Brain Development compiled a longitudinal normative reference database of neuroimaging and correlated clinical/behavioral data from a demographically representative sample of healthy children and adolescents aged newborn through early adulthood. The present paper reports brain volume data for 325 children, ages 4.5-18 years, from the first cross-sectional time point. Measures included volumes of whole-brain gray matter (GM) and white matter (WM), left and right lateral ventricles, frontal, temporal, parietal and occipital lobe GM and WM, subcortical GM (thalamus, caudate, putamen, and globus pallidus), cerebellum, and brainstem. Associations with cross-sectional age, sex, family income, parental education, and body mass index (BMI) were evaluated. Key observations are: 1) age-related decreases in lobar GM most prominent in parietal and occipital cortex; 2) age-related increases in lobar WM, greatest in occipital, followed by the temporal lobe; 3) age-related trajectories predominantly curvilinear in females, but linear in males; and 4) small systematic associations of brain tissue volumes with BMI but not with IQ, family income, or parental education. These findings constitute a normative reference on regional brain volumes in children and adolescents.

  11. Error analysis of measuring diameter at breast height and tree height and volume of standing tree by total station%全站仪测量立木胸径树高及材积的误差分析

    Institute of Scientific and Technical Information of China (English)

    于东海; 冯仲科; 曹忠; 蒋君志伟

    2016-01-01

    Diameter at breast height (DBH), tree height and volume are the most significant factors in forestry investigation. The measurement precision of DBH and tree height directly affects the accuracy of individual volume. In traditional forestry works, cutting down trees and using analytic timber are for compiling the volume tables, which are yet faced with the problems such as high consumption, low efficiency and large destruction. In recent years, the emergence of the modern instruments gradually lays the foundation for achieving high precision nondestructive standing tree measurements. Total station is a kind of precise tool that can be used to measure distance and angle and to process data automatically. And it will be widely used in forestry production practice and scientific research in the future because of the high measurement accuracy, so studying the accuracy of measuring trees has practical significance for the forestry work. Calculating DBH, tree height and volume by measuring zenith angles, horizontal angles and distance from the center of the instrument to the tree is the principle of measuring standing trees by using total station. Based on the theory of measuring DBH, tree height and volume of standing tree by total station and taking the variance and covariance of measurement factors into consideration, the research deduced the mathematical models to calculate the error of DBH, height and volume of standing tree according to error propagation laws. We chose larches in Beijing as the experimental samples, and analyzed 10 sample groups of different sizes for the difference of relative errors. The results show: 1) There are correlations between the height and the diameter of random tree section, and the value range of correlation coefficientis (0, 0.3); besides, the variance and covariance of these 2 factors affect the error of each segment volume; furthermore, the error of total volume is affected not only by the variance of each section volume, but also

  12. DESIGN INFORMATION ON FINE PORE AERATION SYSTEMS

    Science.gov (United States)

    Field studies were conducted over several years at municipal wastewater treatment plants employing line pore diffused aeration systems. These studies were designed to produce reliable information on the performance and operational requirements of fine pore devices under process ...

  13. Investigation of electrolyte wetting in lithium ion batteries: Effects of electrode pore structures and solution

    Science.gov (United States)

    Sheng, Yangping

    , which are further described by the percentage of total pore volume and the threshold and critical pore diameter. The effect of calendering process on electrolyte wetting, as a demonstration for typical post-production process, has been revealed by the wetting balance analysis. A quantitative analysis of the pore structure under the pore network concept is used to investigate the evolution of pore structure with the increase of calendering force. Based on the pore structure, the hypothesis of combined effects of capillary and converging-diverging flow in electrolyte wetting is proposed to understand the mechanism. A further demonstration of the effect of production process by adding excessive carbon black is accomplished. The hypothesis is valid to explain the electrolyte wetting behavior with increasing amount of carbon black. The pore structure differences between electrodes with various amount of carbon black are shown by the scanning electron microscope.

  14. Effect of Pore Structure of Cigarette Paper on the Yield of Carbon Monoxide in Mainstream Smoke During Cigarette Burning

    Directory of Open Access Journals (Sweden)

    Wei Luo

    2015-06-01

    Full Text Available Deux papiers à cigarettes furent préparés, qui présentaient la même masse surfacique et la même perméabilité mais se distinguaient par la structures de leurs pores. L’incidence de la structure des pores, après pyrolyse, sur le rendement de CO au niveau de la fumée principale fut analysée en soumettant ces papiers à des températures de 250 °C. La diffusivité, la perméabilité, la distribution de la taille des pores et le volume des pores de ces papiers à cigarettes furent également mesurés avant et après chauffage. Les structures des pores du papier à cigarettes totalement pyrolysé dans le cône de combustion et la zone partiellement pyrolysée à proximité de la ligne de carbonisation furent dégagées. Le rendement en CO de la fumée principale et de la fumée latérale ainsi que la distribution des températures du cône de combustion furent évalués. La diffusivité et la perméabilité des papiers à cigarettes observées après chauffage furent nettement plus élevées que celles de l’échantillon de référence après chauffage. Le volume des pores du papier à cigarettes d’une épaisseur de 0,1-8,0 μm se trouva accrue, ce qui diminua la teneur en CO de la fumée principale. Une augmentation du nombre de micropores facilite la diffusion du CO de la fumée principale vers la fumée latérale.

  15. Detection and Influence of Shrinkage Pores and Nonmetallic Inclusions on Fatigue Life of Cast Aluminum Alloys

    Science.gov (United States)

    Tijani, Yakub; Heinrietz, André; Stets, Wolfram; Voigt, Patrick

    2013-12-01

    In the current study, test bars of cast aluminum alloys EN AC-AlSi8Cu3 and EN AC-AlSi7Mg0.3 were produced with a defined amounts of shrinkage pores and oxides. For this purpose, a permanent mold with heating and cooling devices for the generation of pores was constructed. The oxides were produced by contaminating the melt. The specimens and their corresponding defect distributions were examined and quantified by X-ray computer tomography (CT) and quantitative metallography, respectively. A special test algorithm for the simultaneous image analyses of pores and oxides was developed. Fatigue tests were conducted on the defective samples. It was found that the presence of shrinkage pores lowers the fatigue strength, and only few oxide inclusions were found to initiate fatigue cracks when shrinkage pores are present. The results show that the pore volume is not sufficient to characterize the influence of shrinkage pores on fatigue life. A parametric model for the calculation of fatigue life based on the pore parameters obtained from CT scans was implemented. The model accounts for the combined impact of pore location, size, and shape on fatigue life reduction.

  16. Effect of hydrofluoric acid (HF) concentration to pores size diameter of silicon membrane.

    Science.gov (United States)

    Burham, Norhafizah; Hamzah, Azrul Azlan; Majlis, Burhanuddin Yeop

    2014-01-01

    This paper studies parameters which affect the pore size diameter of a silicon membrane. Electrochemical etching is performed in characterise the parameter involved in this process. The parameter has been studied is volume ratio of hydrofluoric acid (HF) and ethanol as an electrolyte aqueous for electrochemical etch. This electrolyte aqueous solution has been mixed between HF and ethanol with volume ratio 3:7, 5:5, 7:3 and 9:1. As a result, the higher volume of HF in this electrolyte gives the smallest pore size diameter compared to the lower volume of HF. These samples have been dipped into HF and ethanol electrolyte aqueous with supplied 25 mA/cm2 current density for 20, 30, 40, and 50 minutes. The samples will inspect under Scanning Electron Microscope (SEM) to execute the pore formations on silicon membrane surface.

  17. A Stereolithography Pore-Throat Model

    Science.gov (United States)

    Crandall, D.; Ahmadi, G.; Ferer, M.; Smith, D. H.

    2007-12-01

    A new experimental, heterogeneous pore-throat model has been designed and fabricated using stereolithography (SL). In SL production, a laser cures a thin layer of photo-sensitive resin on the surface of a vat of liquid resin; a moveable platform then submerges the cured layer and a new layer is cured on top of the previous one, creating a physical model from a computer generated model. This layered fabrication of a computer generated model has enabled the production of an experimental porous medium with improved fluid resistance properties, as compared to previously studied, constant-height etched cells. A uniform distribution of throat widths was randomly placed throughout the pore-throat matrix and the throat height of each throat was assigned to increase the range of viscous and capillary resistances within the physical model. This variation in both throat height and width generated a porous medium with fairly low porosity (43%), permeability (~400 D), and wide range of geometric resistance properties. Experimental, two-phase immiscible drainage studies in the porous flowcell were performed. Analysis of the captured images was performed with open-source image processing software. These analysis techniques utilized the capability of both ImageJ and the Gnu Image Manipulation Program to be customized with ancillary codes. This enabled batch procedures to be created that converted the original grey-scale bitmaps to binary data sets, which were then analyzed with in-house codes. The fractal dimension, Df, (measured with box-counting) and percent saturation of these experiments were calculated and shown to compare favorably to fractal predictions and previous flowcell studies. Additionally, using the computer generated pore-throat geometry, a computational fluid dynamics model of two- phase flow through the porous medium was created. This model was created using FLUENT code and the Volume of Fluid method. The percent saturation of the less-viscous invading fluid

  18. Reactive transport in porous media for CO2 sequestration: Pore scale modeling using the lattice Boltzmann method

    Science.gov (United States)

    Gao, Jinfang; Xing, Huilin; Tian, Zhiwei; Pearce, Julie K.; Sedek, Mohamed; Golding, Suzanne D.; Rudolph, Victor

    2017-01-01

    Injection of CO2 subsurface may lead to chemical reactivity of rock where CO2 is dissolved in groundwater. This process can modify pore networks to increase or decrease porosity through mineral dissolution and precipitation. A lattice Boltzmann (LB) based computational model study on the pore scale reactive transport in three dimensional heterogeneous porous media (sandstone consisting of both reactive and non-reactive minerals) is described. This study examines how fluid transport in porous materials subject to reactive conditions is affected by unsteady state local reactions and unstable dissolution fronts. The reaction of a calcite cemented core sub-plug from the Hutton Sandstone of the Surat Basin, Australia, is used as a study case. In particular, the work studies the interaction of acidic fluid (an aqueous solution with an elevated concentration of carbonic acid) with reactive (e.g. calcite) and assumed non-reactive (e.g. quartz) mineral surfaces, mineral dissolution and mass transfer, and resultant porosity change. The proposed model is implemented in our custom LBM code and suitable for studies of multiple mineral reactions with disparate reaction rates. A model for carbonic acid reaction with calcite cemented sandstone in the CO2-water-rock system is verified through laboratory experimental data including micro-CT characterization before and after core reaction at reservoir conditions. The experimentally validated model shows: (1) the dissolution of calcite cement forms conductive channels at the pore scale, and enables the generation of pore throats and connectivity; (2) the model is able to simulate the reaction process until the reaction equilibrium status is achieved (around 1440 days); (3) calcite constituting a volume of around 9.6% of the whole core volume is dissolved and porosity is consequently increased from 1.1% to 10.7% on reaching equilibrium; (4) more than a third of the calcite (constituting 7.4% of the total core volume) is unaffected

  19. Pore formation by Cry toxins.

    Science.gov (United States)

    Soberón, Mario; Pardo, Liliana; Muñóz-Garay, Carlos; Sánchez, Jorge; Gómez, Isabel; Porta, Helena; Bravo, Alejandra

    2010-01-01

    Bacillus thuringiensis (Bt) bacteria produce insecticidal Cry and Cyt proteins used in the biological control of different insect pests. In this review, we will focus on the 3d-Cry toxins that represent the biggest group of Cry proteins and also on Cyt toxins. The 3d-Cry toxins are pore-forming toxins that induce cell death by forming ionic pores into the membrane of the midgut epithelial cells in their target insect. The initial steps in the mode of action include ingestion of the protoxin, activation by midgut proteases to produce the toxin fragment and the interaction with the primary cadherin receptor. The interaction of the monomeric CrylA toxin with the cadherin receptor promotes an extra proteolytic cleavage, where helix alpha-1 of domain I is eliminated and the toxin oligomerization is induced, forming a structure of 250 kDa. The oligomeric structure binds to a secondary receptor, aminopeptidase N or alkaline phosphatase. The secondary receptor drives the toxin into detergent resistant membrane microdomains formingpores that cause osmotic shock, burst of the midgut cells and insect death. Regarding to Cyt toxins, these proteins have a synergistic effect on the toxicity of some Cry toxins. Cyt proteins are also proteolytic activated in the midgut lumen of their target, they bind to some phospholipids present in the mosquito midgut cells. The proposed mechanism of synergism between Cry and Cyt toxins is that Cyt1Aa function as a receptor for Cry toxins. The Cyt1A inserts into midgut epithelium membrane and exposes protein regions that are recognized by Cry11Aa. It was demonstrated that this interaction facilitates the oligomerization of Cry11Aa and also its pore formation activity.

  20. Analysis of Pore Structures and Their Relations with Strength of Hardened Cement Paste

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wensheng; LI Beixing; WANG Hongxia; WEI Jiangxiong; CHEN Yimin

    2005-01-01

    Three cement samples were prepared, including OPC consisted of 100wt% portland cement, PFA consisted of 70wt% portland cement and 30wt% fly-ash, and CA consisted of 70wt% portland cement and 30wt% modified fly ash. The strength of hardened cement paste of these samples was tested and their pore structures were determined by a mercury intrusion porosimeter. Moreover,the data of the pore structures of three samples were comprehensively analyzed. The relations between the pore structures and the compressive strength of the three samples were studied. The experimental results show that the relations between the porosity determined by the mercury intrusion porosimeter and the compressive strength are not notable, and the total pore surface area, the average pore diameter and the median pore diameter could be used to explain the difference of the strength of the tested samples.

  1. Influence of stress-path on pore size distribution in granular materials

    Directory of Open Access Journals (Sweden)

    Das Arghya

    2017-01-01

    Full Text Available Pore size distribution is an important feature of granular materials in the context of filtration and erosion in soil hydraulic structures. Present study focuses on the evolution characteristics of pore size distribution for numerically simulated granular assemblies while subjected to various compression boundary constrain, namely, conventional drained triaxial compression, one-dimensional or oedometric compression and isotropic compression. We consider the effects initial packing of the granular assembly, loose or dense state. A simplified algorithm based on Delaunay tessellation is used for the estimation of pore size distribution for the deforming granular assemblies at various stress states. The analyses show that, the evolution of pore size is predominantly governed by the current porosity of the granular assembly while the stress path or loading process has minimal influence. Further it has also been observed that pore volume distribution reaches towards a critical distribution at the critical porosity during shear enhanced loading process irrespective of the deformation mechanism either compaction or dilation.

  2. Influence of stress-path on pore size distribution in granular materials

    Science.gov (United States)

    Das, Arghya; Kumar, Abhinav

    2017-06-01

    Pore size distribution is an important feature of granular materials in the context of filtration and erosion in soil hydraulic structures. Present study focuses on the evolution characteristics of pore size distribution for numerically simulated granular assemblies while subjected to various compression boundary constrain, namely, conventional drained triaxial compression, one-dimensional or oedometric compression and isotropic compression. We consider the effects initial packing of the granular assembly, loose or dense state. A simplified algorithm based on Delaunay tessellation is used for the estimation of pore size distribution for the deforming granular assemblies at various stress states. The analyses show that, the evolution of pore size is predominantly governed by the current porosity of the granular assembly while the stress path or loading process has minimal influence. Further it has also been observed that pore volume distribution reaches towards a critical distribution at the critical porosity during shear enhanced loading process irrespective of the deformation mechanism either compaction or dilation.

  3. Influence of carbonization conditions on micro-pore structure of foundry formed coke produced with char

    Energy Technology Data Exchange (ETDEWEB)

    Jun Qiao; Jianjun Wu; Jingru Zu; Zhiyuan Gao; Guoli Zhou

    2009-07-01

    There are few studies on coke's micro-pore structure in recent years, however, micro-pore structure of foundry coke determines its macroscopically quality index and reactivity in cupola furnace. Effect of such factors on micro-pore structure were investigated under different carbonization conditions with certain ratio of raw materials and material forming process in this article as charging temperature (A); braised furnace time (B); heating rate of the first stage (C)and the second stage (D) and holding time of ultimate temperature (E). Research showed that charging temperature was the most influential factor on the coke porosity, pore volume, pore size and specific surface area. It is suggested that formation of plastic mass and releasing rate of volatile during carbonization period are two main factors on microstructure of foundry coke while charging temperature contributes most to the above factors. 6 refs., 4 figs., 9 tabs.

  4. Pore structure and dielectric behaviour of the 3D collagen-DAC scaffolds designed for nerve tissue repair.

    Science.gov (United States)

    Pietrucha, Krystyna; Marzec, Ewa; Kudzin, Marcin

    2016-11-01

    The design and selection of a suitable scaffold with well-defined pores size distribution and dielectric properties are critical features for neural tissue engineering. In this study we use mercury porosimetry and the dielectric spectroscopy in the alpha-dispersion region of the electric field to determine the microarchitecture and activation energy of collagen (Col) modified by 2,3 dialdehyde cellulose (DAC). The scaffold was synthesized in three steps: (i) preparation of DAC by oxidation of cellulose, (ii) construction of a 3D Col sponge-shape or film, (iii) cross-linkage of the Col samples using DAC. The activation energy needed to break the bonds formed by water in the Col-DAC composite is approximately 2 times lower than that in the unmodified Col. In addition, the magnitude of conductivity for modified Col at 70°C is approximately 40% lower than that recorded for the unmodified Col. The largest fraction, of which at least 70% of the total pore volume comprises the sponge, is occupied by pores ranging from 20 to 100μm in size. The knowledge on the dielectric behaviour and microstructure of the Col-DAC scaffold may prove relevant to neural tissue engineering focused on the regeneration of the nervous system. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. A pore scale investigation of crude oil distribution and removal from homogeneous porous media during surfactant-induced remediation.

    Science.gov (United States)

    Ghosh, Jaydeep; Tick, Geoffrey R

    2013-12-01

    A pore-scale study was conducted to understand interfacial processes contributing to the removal of crude oils from a homogeneous porous medium during surfactant-induced remediation. Synchrotron X-ray microtomography (SXM) was used to obtain high-resolution three-dimensional images of the two-fluid-phase oil/water system, and quantify temporal changes in oil blob distribution, blob morphology, and blob surface area before and after sequential surfactant flooding events. The reduction of interfacial tension in conjunction with the sufficient increase in viscous forces as a result of surfactant flushing was most likely responsible for mobilization and recovery of the two lighter oil fractions. However, corresponding increases in viscous forces as a result of a reduction of interfacial tension were insufficient to initiate and maintain the displacement (recovery) of the heavy crude oil fraction during surfactant flushing. In contrast to the heavy oil system, changes in trapping number for the lighter fraction crude oils were sufficient to initiate mobilization as a result of surfactant flushing. Both light and medium oil fractions showed an increase in the number of blobs and total blob surface area, and a reduction in the total volume after 2 pore volumes (PVs) of surfactant flooding. This increase in surface area was attributed to the change in blob morphology from spherical to more complex non-spherical ganglia shape characteristics. Moreover, the increase in the number of oil blobs from larger to smaller particles after surfactant flushing may have contributed to the greater cumulative oil surface area. Complete recovery of light and medium oil fractions resulted after 5 PVs of surfactant flooding, whereas the displacement efficiency of heavy-oil fraction was severely limited, even after extended periods of flushing. The results of these experiments demonstrate the utility of SXM for quantifying pore-scale interfacial characteristics for specific crude

  6. Intumescence and pore structure of alkali-activated volcanic glasses upon exposure to high temperatures

    Science.gov (United States)

    Erdogan, S. T.

    2015-12-01

    Structures formed with ground perlite, a natural volcanic glass, activated with NaOH solutions, are shown to possess the ability to expand up to ~225 % of their original volumes upon exposure to temperatures in the 200-600 °C range. Porous solid with 3-7 MPa compressive strength and ˜450 kg/m3 or higher density are obtained. The observed expansion is believed to occur due to a loss of silanol condensation water, as vapor and is accompanied by an up to ~20 % loss in mass. A drop in pH to near-neutral values supports this idea. The size and total amount of pores in the final solid are controlled by concentration of the NaOH solution and thermal processing conditions. The pores formed are observed to be ~1-10 μm to mm-sized. The ability of perlite-based solids to intumesce over specific temperature ranges could be beneficial in applications where absorption of thermal energy is necessary, such as passive fire protection.

  7. USING A NEW FINITE SLIT PORE MODEL FOR NLDFT ANALYSIS OF CARBON PORE STRUCTURE

    Energy Technology Data Exchange (ETDEWEB)

    Jagiello, Jacek [Micromeritics Instrument Corporation; Kenvin, Jeffrey [Micromeritics Instrument Corporation; Oliver, James P [Micromeritics Instrument Corporation; Lupini, Andrew R [ORNL; Contescu, Cristian I [ORNL

    2011-01-01

    In this work, we present a model for analyzing activated carbon micropore structures based on graphene sheet walls of finite thickness and extent. This is a two-dimensional modification of the widely used infinite slit pore model that assumes graphite-like infinitely extended pore walls. The proposed model has two versions: (1) a strip pore constructed with graphene strip walls that have finite length L in the x direction and are infinite in the y direction. Strip pores are open on both sides in the x direction. (2) A channel pore is a strip pore partially closed along one edge by a perpendicularly oriented graphene wall. This more realistic model allows pore termination via both physical pore entrances and pore blockage. The model consequently introduces heterogeneity of the adsorption potential that is reduced near pore entrances and enhanced near corners of pore walls. These energetically heterogeneous structures fill with adsorbate more gradually than homogeneous pores of the same width. As a result, the calculated adsorption isotherms are smoother and less steep for the finite versus the infinite pore model. In the application of this model for carbon characterization it is necessary to make an assumption about the pore length. In this work we made this assumption based on the high resolution scanning transmission electron microscopy (STEM) results. We find the agreement between the experiment and the model significantly better for the finite than for the infinite pore model.

  8. Determination of Matrix Pore Size Distribution in Fractured Clayey Till and Assessment of Matrix Migration of Dechlorinationg Bacteria

    DEFF Research Database (Denmark)

    Cong, Lu; Broholm, Mette Martina; Fabricius, Ida Lykke

    2014-01-01

    The pore structure and pore size distribution (PSD) in the clayey till matrix from three Danish field sites were investigated by image analysis to assess the matrix migration of dechlorinating bacteria in clayey till. Clayey till samples had a wide range of pore sizes, with diameters of 0.1–100 μm...... account for approximately 30–60% of the total porosity (20–26%), which is within the range of those reported for clayey soils and other clayey deposits in the literature. The pore size, PSD, and interconnectivity of pores in clayey till matrix may play an important role in evaluation of the migration...

  9. Benchmark Study of 3D Pore-scale Flow and Solute Transport Simulation Methods

    Science.gov (United States)

    Scheibe, T. D.; Yang, X.; Mehmani, Y.; Perkins, W. A.; Pasquali, A.; Schoenherr, M.; Kim, K.; Perego, M.; Parks, M. L.; Trask, N.; Balhoff, M.; Richmond, M. C.; Geier, M.; Krafczyk, M.; Luo, L. S.; Tartakovsky, A. M.

    2015-12-01

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that benchmark study to include additional models of the first type based on the immersed-boundary method (IMB), lattice Boltzmann method (LBM), and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries in the manner of PNMs has not been fully determined. We apply all five approaches (FVM-based CFD, IMB, LBM, SPH and PNM) to simulate pore-scale velocity distributions and nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The benchmark study was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This study provides support for confidence in a variety of pore-scale modeling methods, and motivates further development and application of pore-scale simulation methods.

  10. Intercomparison of 3D pore-scale flow and solute transport simulation methods

    Science.gov (United States)

    Yang, Xiaofan; Mehmani, Yashar; Perkins, William A.; Pasquali, Andrea; Schönherr, Martin; Kim, Kyungjoo; Perego, Mauro; Parks, Michael L.; Trask, Nathaniel; Balhoff, Matthew T.; Richmond, Marshall C.; Geier, Martin; Krafczyk, Manfred; Luo, Li-Shi; Tartakovsky, Alexandre M.; Scheibe, Timothy D.

    2016-09-01

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing a standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that validation to include additional models of the first type based on the lattice Boltzmann method (LBM) and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). The PNM approach used in the current study was recently improved and demonstrated to accurately simulate solute transport in a two-dimensional experiment. While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries on solute transport in the manner of PNMs has not been fully determined. We apply all four approaches (FVM-based CFD, LBM, SPH and PNM) to simulate pore-scale velocity distributions and (for capable codes) nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The intercomparison work was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This study provides support for confidence

  11. Synchrotron microtomographic quantification of geometrical soil pore characteristics affected by compaction

    Science.gov (United States)

    Udawatta, Ranjith P.; Gantzer, Clark J.; Anderson, Stephen H.; Assouline, Shmuel

    2016-05-01

    Soil compaction degrades soil structure and affects water, heat, and gas exchange as well as root penetration and crop production. The objective of this study was to use X-ray computed microtomography (CMT) techniques to compare differences in geometrical soil pore parameters as influenced by compaction of two different aggregate size classes. Sieved (diameter Compaction reduced porosity, average pore size, number of pores, and characteristic constants. The average pore radii (63.7 and 61 µm; p < 0.04), largest pore volume (1.58 and 0.58 mm3; p = 0.06), number of pores (55 and 50; p = 0.09), and characteristic coordination number (3.74 and 3.94; p = 0.02) were significantly different between the low-density than the high-density treatment. Aggregate size also influenced measured geometrical pore parameters. This analytical technique provides a tool for assessing changes in soil pores that affect hydraulic properties and thereby provides information to assist in assessment of soil management systems.

  12. Variational-based segmentation of bio-pores in tomographic images

    Science.gov (United States)

    Bauer, Benjamin; Cai, Xiaohao; Peth, Stephan; Schladitz, Katja; Steidl, Gabriele

    2017-01-01

    X-ray computed tomography (CT) combined with a quantitative analysis of the resulting volume images is a fruitful technique in soil science. However, the variations in X-ray attenuation due to different soil components keep the segmentation of single components within these highly heterogeneous samples a challenging problem. Particularly demanding are bio-pores due to their elongated shape and the low gray value difference to the surrounding soil structure. Recently, variational models in connection with algorithms from convex optimization were successfully applied for image segmentation. In this paper we apply these methods for the first time for the segmentation of bio-pores in CT images of soil samples. We introduce a novel convex model which enforces smooth boundaries of bio-pores and takes the varying attenuation values in the depth into account. Segmentation results are reported for different real-world 3D data sets as well as for simulated data. These results are compared with two gray value thresholding methods, namely indicator kriging and a global thresholding procedure, and with a morphological approach. Pros and cons of the methods are assessed by considering geometric features of the segmented bio-pore systems. The variational approach features well-connected smooth pores while not detecting smaller or shallower pores. This is an advantage in cases where the main bio-pores network is of interest and where infillings, e.g., excrements of earthworms, would result in losing pore connections as observed for the other thresholding methods.

  13. Methane adsorption behavior on coal having different pore structures

    Institute of Scientific and Technical Information of China (English)

    Zhao; Yi; Jiang; Chengfa; Chu; Wei

    2012-01-01

    The adsorption of methane onto five dry coal samples was measured at 298 K over the pressure range from 0 to 3.5 MPa using a volumetric method.The isotherm data were fitted to the Langmuir and the Freundlich equations.The kinetic data were fitted to a pseudo second order equation,the linear driving force equation(LDF),and an intra-particle diffusion model.These results showed that higher methane adsorption is correlated with larger micro-pore volumes and specific surface areas.The adsorption was related to the narrow micro-pore size distribution when the previous two parameters are large.The kinetics study showed that the kinetics of methane adsorption onto these five dry coal samples followed a pseudo second order model very well.Methane adsorption rates are controlled by intra-particle diffusion.The faster the intra-particle diffusion,the faster the methane adsorption rate will be.

  14. Microlens arrays with integrated pores

    Directory of Open Access Journals (Sweden)

    Shu Yang

    2005-12-01

    Full Text Available Microlenses are important optical components that image, detect, and couple light. But most synthetic microlenses have fixed position and shape once they are fabricated, so their possible range of tunability and complexity is rather limited. By comparison, biology provides many varied, new paradigms for the development of adaptive optical networks. Here, we discuss inspirational examples of biological lenses and their synthetic analogs. We focus on the fabrication and characterization of biomimetic microlens arrays with integrated pores, whose appearance and function are similar to highly efficient optical elements formed by brittlestars. The complex design can be created by three-beam interference lithography. The synthetic lens has strong focusing ability for use as an adjustable lithographic mask and a tunable optical device coupled with the microfluidic system. Replacing rigid microlenses with soft hydrogels provides a way of changing the lens geometry and refractive index continuously in response to external stimuli, resulting in intelligent, multifunctional, tunable optics.

  15. Atomic Structure of Graphene Subnanometer Pores.

    Science.gov (United States)

    Robertson, Alex W; Lee, Gun-Do; He, Kuang; Gong, Chuncheng; Chen, Qu; Yoon, Euijoon; Kirkland, Angus I; Warner, Jamie H

    2015-12-22

    The atomic structure of subnanometer pores in graphene, of interest due to graphene's potential as a desalination and gas filtration membrane, is demonstrated by atomic resolution aberration corrected transmission electron microscopy. High temperatures of 500 °C and over are used to prevent self-healing of the pores, permitting the successful imaging of open pore geometries consisting of between -4 to -13 atoms, all exhibiting subnanometer diameters. Picometer resolution bond length measurements are used to confirm reconstruction of five-membered ring projections that often decorate the pore perimeter, knowledge which is used to explore the viability of completely self-passivated subnanometer pore structures; bonding configurations where the pore would not require external passivation by, for example, hydrogen to be chemically inert.

  16. Pore structure of ore granular media by computerized tomography image processing

    Institute of Scientific and Technical Information of China (English)

    WU Ai-xiang; YANG Bao-hua; XI Yong; JIANG Huai-chun

    2007-01-01

    The pore structure images of ore particles located at different heights of leaching column were scanned with X-ray computerized tomography (CT) scanner, the porosity and pore size distribution were calculated and the geometrical shape and connectivity of pores were analyzed based on image process method, and the three dimensional reconstruction of pore structure images was realized. The results show that the porosity of ore particles bed in leaching column is 42.92%, 41.72%, 39.34% at top,middle and bottom zone, respectively. Obviously it has spatial variability and decreases appreciably along the height of the column.The overall average porosity obtained by image processing is 41.33% while the porosity gotten from general measurement method in laboratory is 42.77% showing the results of both methods are consistent well. The pore structure of ore granular media is characterized as a dynamical space network composed of interconnected pore bodies and pore throats. The ratio of throats with equivalent diameter less than 1.91 mm to the total pores is 29.31%, and that of the large pores with equivalent diameter more than 5.73 mm is 2.90%.

  17. Effect of support structure on CO2 adsorption properties of pore-expanded hyperbranched aminosilicas

    KAUST Repository

    Drese, Jeffrey H.

    2012-03-01

    Hyperbranched aminosilica (HAS) CO 2 adsorbents are prepared by the ring-opening polymerization of aziridine from SBA-15 mesoporous silica, as in the original synthesis of HAS materials, as well as over an array of new support materials with substantially larger average pore diameters to elucidate the effect of support porosity on final adsorbent properties. Pore-expanded hyperbranched aminosilica (PEHAS) CO 2 adsorbents are prepared from several different pore-expanded, ordered mesoporous silicas including pore-expanded SBA-15, mesocellular foam, and a large-pore commercial silica. The effect of the nature of the silica support is determined by examining the degree of aziridine polymerization and the CO 2 adsorption kinetics and capacities of the resulting organic/inorganic hybrid materials. Comparisons are made to non-pore-expanded SBA-15 based HAS adsorbents, reported previously, where pores become blocked at higher amine loadings. The PEHAS materials unexpectedly possess lower amine loadings than the previously reported HAS materials and do not exhibit pore blocking. The use of acetic acid as a catalyst during PEHAS synthesis only marginally increases amine loading. The adsorption kinetics of PEHAS adsorbents are similar to HAS adsorbents with low amine loadings and do not show the detrimental effects of pore-blocking. However, the inability to synthesize PEHAS adsorbents with high amine loadings via this approach limits the total amount of CO 2 captured per gram of material, compared to HAS adsorbents with high amine loadings. © 2011 Elsevier Inc. All rights reserved.

  18. Total Thyroidectomy

    Directory of Open Access Journals (Sweden)

    Lopez Moris E

    2016-06-01

    Full Text Available Total thyroidectomy is a surgery that removes all the thyroid tissue from the patient. The suspect of cancer in a thyroid nodule is the most frequent indication and it is presume when previous fine needle puncture is positive or a goiter has significant volume increase or symptomes. Less frequent indications are hyperthyroidism when it is refractory to treatment with Iodine 131 or it is contraindicated, and in cases of symptomatic thyroiditis. The thyroid gland has an important anatomic relation whith the inferior laryngeal nerve and the parathyroid glands, for this reason it is imperative to perform extremely meticulous dissection to recognize each one of these elements and ensure their preservation. It is also essential to maintain strict hemostasis, in order to avoid any postoperative bleeding that could lead to a suffocating neck hematoma, feared complication that represents a surgical emergency and endangers the patient’s life.It is essential to run a formal technique, without skipping steps, and maintain prudence and patience that should rule any surgical act.

  19. Pore structure modification of diatomite as sulfuric acid catalyst support by high energy electron beam irradiation and hydrothermal treatment

    Science.gov (United States)

    Li, Chong; Zhang, Guilong; Wang, Min; Chen, Jianfeng; Cai, Dongqing; Wu, Zhengyan

    2014-08-01

    High energy electron beam (HEEB) irradiation and hydrothermal treatment (HT), were applied in order to remove the impurities and enlarge the pore size of diatomite, making diatomite more suitable to be a catalyst support. The results demonstrated that, through thermal, charge, impact and etching effects, HEEB irradiation could make the impurities in the pores of diatomite loose and remove some of them. Then HT could remove rest of them from the pores and contribute significantly to the modification of the pore size distribution of diatomite due to thermal expansion, water swelling and thermolysis effects. Moreover, the pore structure modification improved the properties (BET (Brunauer-Emmett-Teller) specific surface area, bulk density and pore volume) of diatomite and the catalytic efficiency of the catalyst prepared from the treated diatomite.

  20. Quantitative assessment of pore development at Al2O3/FeAl interfaces during high temperature oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Peggy Y.; Van Leiden, C.; Niu, Y.; Gesmundo, F.

    2001-04-24

    Alloys of commercial grades that do not contain a reactive element, such as yttrium, often develop pores at the scale/alloy interface. The accumulation and growth of these pores greatly weaken scale adhesion. The purpose of this study is to evaluate pore development in Fe-40at% Al and determine the change in pore volume with oxidation time. Experimental results are then compared to a theoretical calculation where all vacancies are allowed to condense as voids. After removing the oxide scales that formed after various times of oxidation at 1000 C in oxygen, the alloy surface was analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to determine the size and depth of interfacial pores. Results are discussed in light of possible mechanisms involved in pore formation at scale/alloy interfaces.

  1. Pore space characterization in carbonate rocks - Approach to combine nuclear magnetic resonance and elastic wave velocity measurements

    Science.gov (United States)

    Müller-Huber, Edith; Schön, Jürgen; Börner, Frank

    2016-04-01

    Pore space features influence petrophysical parameters such as porosity, permeability, elastic wave velocity or nuclear magnetic resonance (NMR). Therefore they are essential to describe the spatial distribution of petrophysical parameters in the subsurface, which is crucial for efficient reservoir characterization especially in carbonate rocks. While elastic wave velocity measurements respond to the properties of the solid rock matrix including pores or fractures, NMR measurements are sensitive to the distribution of pore-filling fluids controlled by rock properties such as the pore-surface-to-pore-volume ratio. Therefore a combination of both measurement principles helps to investigate carbonate pore space using complementary information. In this study, a workflow is presented that delivers a representative average semi-axis length of ellipsoidal pores in carbonate rocks based on the pore aspect ratio received from velocity interpretation and the pore-surface-to-pore-volume ratio Spor as input parameters combined with theoretical calculations for ellipsoidal inclusions. A novel method to calculate Spor from NMR data based on the ratio of capillary-bound to movable fluids and the thickness of the capillary-bound water film is used. To test the workflow, a comprehensive petrophysical database was compiled using micritic and oomoldic Lower Muschelkalk carbonates from Germany. The experimental data indicate that both mud-dominated and grain-dominated carbonates possess distinct ranges of petrophysical parameters. The agreement between the predicted and measured surface-to-volume ratio is satisfying for oomoldic and most micritic samples, while pyrite or significant sample heterogeneity may lead to deviations. Selected photo-micrographs and scanning electron microscope images support the validity of the estimated representative pore dimensions.

  2. ASSESSMENT OF THE TOTAL PETROLEUM HYDROCARBON CONTENT OF AGRICULTURAL SOIL POLLUTED WITH DIFFERENT VOLUME OF CRUDE OIL DURING PLANT- MICROBE INTERACTION

    Directory of Open Access Journals (Sweden)

    Toochukwu Ekwutosi OGBULIE

    2014-06-01

    Full Text Available The effectiveness of plants in interaction with indigenous organisms in environmental clean –up was evaluated. The agricultural soil used for the study was polluted with 100ml, 200ml, 400ml and 800ml of Bonny light crude oil [100%]. Pre and post Microbial examination of the polluted soil identified the indigenous flora present in the soil to be Penicillum sp Aspergillus fumigatus, Aspergillus niger, Candida sp, Pseudomonas fluorescence, Acinetobacter baumanni, Bacillus mycoides, Klebsiella sp., Staphylococcus aureus and Escherichia coli though the absence of S aureus and E. coli was evident during the latter. Vigna unguiculata var unguiculata, Mucuna pruriens, Zea mays and Telfairia occidentalis were the test plant used. Gas chromatographic (GC analysis revealed the total petroleum hydrocarbon (TPH of polluted soil on comparison with the value of 10,380 kg/ mg for control sample, to be low. The high TPH obtained from samples polluted with higher concentration depicts that the numbers of plants to be cultivated for remediation could be a determining factor for a faster clean-up. Statistical analysis using analysis of variance (ANOVA model of SPSS software however, showed there was no significant difference in the degradation of crude oil in samples that are in the green house or field.

  3. Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

    Science.gov (United States)

    Yang, Bao-hua; Wu, Ai-xiang; Narsilio, Guillermo A.; Miao, Xiu-xiu; Wu, Shu-yue

    2017-09-01

    Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample (ϕ4.6 mm × 5.6 mm) was scanned using high-resolution X-ray computed tomography (HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 μm. Combined with three-dimensional (3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.

  4. Effects of a 6-Week Upper Extremity Low-Volume, High Intensity Interval Training on Oxygen Uptake, Peak Power Output and Total Exercise Time.

    Science.gov (United States)

    Pinto, Nicole; Salassi, James W; Donlin, Ayla; Schroeder, Jan; Rozenek, Ralph

    2017-05-30

    The purpose of this study was to compare the effects of upper extremity (UE) high intensity interval training (HIIT) to UE continuous training (CT) when training at a similar intensity. 20 participants (mean age = 23 ± 3 yrs) were randomly assigned to either a HIIT (n = 10) or CT (n = 10) group. Participants completed a graded exercise test utilizing arm cranking prior to and following 6 wks (2 sessions · wk-1) of UE training. During sessions, HIIT performed 10 repetitions of 60 s of work at 92.3 ± 1.0% of the arm HRpeak (%aHRpeak) and 60 s of passive recovery (%aHRpeak = 73.0 ± 4.0%) yielding an average training intensity of 82.6 ± 1.5 %aHRpeak. CT exercised for 20 min. at an average intensity of 81.9 ± 2.2 %aHRpeak. Following training HIIT showed greater improvement in V[Combining Dot Above]O2peak compared to CT (Δ = 4.1 ml · min-¹ · kg-¹, 95%CI: 1.3 - 6.9 ml · min-¹ · kg-¹, p = .007). Total exercise time during the post-test GXT was also improved as a result of HIIT (Δ = 1.4 min, 95%CI: 0.4 - 2.3 min, p = .008). Both groups improved peak power output, but no difference was observed between them (Δ = 3.3 W, 95%CI: -3.3 - 9.9 W, p = .305). For a similar time investment, HIIT appeared to improve cardiopulmonary capacity and exercise time to a greater extent than CT and may be a time-efficient alternative for those who incorporate UE aerobic activity into a training program.

  5. Gas transport and subsoil pore characteristics

    DEFF Research Database (Denmark)

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

    2013-01-01

    Arrangements of elementary soil particles during soil deposition and subsequent biological and physical processes in long-term pedogenesis are expected to lead to anisotropy of the non-tilled subsoil pore system. Soil compaction by agricultural machinery is known to affect soil pore characteristi...

  6. Cavitation and pore blocking in nanoporous glasses.

    Science.gov (United States)

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

    2011-09-06

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

  7. Pore structure characteristics after two years biochar application to a sandy loam field

    DEFF Research Database (Denmark)

    Sun, Zhencai; Arthur, Emmanuel; de Jonge, Lis Wollesen

    2015-01-01

    Soil pore structure comprises the size and shape of soil pores and has a major impact on water retention and gas movement. The porous nature of biochar suggests that its application to soil can potentially alter soil pore structure characteristics, and the purpose of this study was to evaluate...... the effects of birch wood biochar (20, 40, and 100 Mg ha−1) applied to a sandy loam on soil total porosity and pore structure indices. Bulk and intact soil samples were collected for physicochemical analyses and water retention and gas diffusivity measurements between pF 1.0 and pF 3.0. Biochar application...... reduced bulk density and increased total porosity especially for soil with 100 Mg ha−1 biochar (16% and 14% reduction in bulk density and total porosity, respectively). Biochar application of more than 20 Mg ha−1 enhanced water retention, and the trend increased with increasing biochar application rate...

  8. Coating of silicon pore optics

    DEFF Research Database (Denmark)

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

    2009-01-01

    For the International X-ray observatory (IXO), a mirror module with an effective area of 3 m2 at 1.25 keV and at least 0.65 m2 at 6 keV has to be realized. To achieve this goal, coated silicon pore optics has been developed over the last years. One of the challenges is to coat the Si plates...... and still to realize Si-Si bonding. It has been demonstrated that ribbed silicon plates can be produced and assembled into stacks. All previously work has been done using uncoated Si plates. In this paper we describe how to coat the ribbed Si plates with an Ir coating and a top C coating through a mask so...... that there will be coating only between the ribs and not in the area where bonding takes place. The paper includes description of the mounting jig and how to align the mask on top of the plate. We will also present energy scans from Si plates coated through a mask....

  9. Particle diffusion in complex nanoscale pore networks

    DEFF Research Database (Denmark)

    Müter, Dirk; Sørensen, Henning Osholm; Bock, H.

    2015-01-01

    decreased to as much as 60% when particle size increased from 1% to 35% of the average pore diameter. When particles were attracted to the pore surfaces, even very small particles, diffusion was drastically inhibited, by as much as a factor of 100. Thus, the size of particles and their interaction......We studied the diffusion of particles in the highly irregular pore networks of chalk, a very fine-grained rock, by combining three-dimensional X-ray imaging and dissipative particle dynamics (DPD) simulations. X-ray imaging data were collected at 25 nm voxel dimension for two chalk samples...... with very different porosities (4% and 26%). The three-dimensional pore systems derived from the tomograms were imported into DPD simulations and filled with spherical particles of variable diameter and with an optional attractive interaction to the pore surfaces. We found that diffusion significantly...

  10. FINGERPRINT MATCHING BASED ON PORE CENTROIDS

    Directory of Open Access Journals (Sweden)

    S. Malathi

    2011-05-01

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

  11. 应用固定砂石总体积法配制大粒径自密实混凝土%Preparation of self-compacting concrete with large diameter aggregate by fixed total volume of sand and gravel

    Institute of Scientific and Technical Information of China (English)

    危加阳; 罗竹容

    2014-01-01

    The method of fixed volume of sand and gravel is commonly used in mixture proportion design of self-compacting concrete. In order to return to the natural properties of aggregate, the method of fixed total volume of sand and gravel that is dif-ferent from the traditional concept is proposed, i. e. , in the mixture proportion design of self-compacting concrete, we should ensure it completely enwrapped, separated and suspended by cementing material. Moreover, this method is also applied in the preparation of self-compacting concrete with the maximum size of 31. 5 mm of coarse aggregate. The practices show that the self-compacting concrete still has good stability of anti-segregation and demonstrates that the preparation of self-compacting con-crete with large diameter aggregate by fixed total volume of sand and gravel is feasible.%固定砂石体积法是设计自密实混凝土配合比的常用方法。为回归骨料的天然属性,提出了有别于传统概念的固定砂石总体积法,即在配制自密实混凝土时,按胶凝材料浆包裹、分隔、悬浮总骨料为目标进行配比计算。同时,在工程实际中,利用该方法尝试将最大粒径为31.5 mm且具有较好抗离析稳定性的粗骨料用于自密实混凝土配制。实践证明,利用固定砂石总体积法配制较大粒径骨料自密实混凝土是可行的。

  12. A bibliography for the conclusions to the special issue of Science of the Total Environment concerning 'The water quality of UK rivers entering the North Sea'. Sci. Tot. Environ., this volume.

    Science.gov (United States)

    Neal, C; Turner, H

    2000-05-05

    In this document, a bibliography for the conclusions to the special issue of Science of the Total Environment concerning 'The water quality of UK rivers entering the North Sea'. Sci. Tot. Environ., this volume, is presented. It comprises a list of the papers presented in five special issues in learned journals, three in Science of the Total Environment (this volume and volumes 194/195, 1997 and 210/211, 1998) as well as Hydrological Processes (1999, vol 13: Special Issue, River Basin Sediment Dynamics, eds. Anderson, M.G., Peters, N.E. and Walling, D.E.) and Marine Pollution Bulletin [1999, vol 37(3-7) Special Issue: Flux of Materials between Rivers and Coastal Waters, eds. Stebbing, A.R.D., Huntley, D. and Leeks, G.J.L.]. The bibliography comprises six main sections with subsections for specific water quality issues. These are as follows: Section 1 deals with the introduction to LOIS and contained in this section is background material over the nature of the programme, the study area, remit, water quality issues and international context. Section 2 provides the main meat to the bibliography and it splits into Section 2.1 historical and Section 2.2 current water quality issues. Within Section 2.2 there are subsections dealing with specific current aspects of water quality (Section 2.2.1, major ions; Section 2.2.2, pH, dissolved carbon dioxide and dissolved oxygen; Section 2.2.3 nutrients; Section 2.2.4, trace elements; Section 2.2.5 micro-organics; Section 2.2.6 sediments; Section 2.2.7 biology). Section 3 deals with hydrology and climate variability, Section 4, modelling, Section 5 load estimation and Section 6 conclusions. A full listing of the LOIS programme is available from the LOIS programme office, CCMS, Plymouth Laboratory, Prospect Place, West Hoe, Plymouth, PL1 3DH, UK (e-mail lois@ccms.ac.uk).

  13. The influence of extraction procedure on ion concentrations in sediment pore water

    Science.gov (United States)

    Winger, P.V.; Lasier, P.J.; Jackson, B.P.

    1998-01-01

    Sediment pore water has the potential to yield important information on sediment quality, but the influence of isolation procedures on the chemistry and toxicity are not completely known and consensus on methods used for the isolation from sediment has not been reached. To provide additional insight into the influence of collection procedures on pore water chemistry, anion (filtered only) and cation concentrations were measured in filtered and unfiltered pore water isolated from four sediments using three different procedures: dialysis, centrifugation and vacuum. Peepers were constructed using 24-cell culture plates and cellulose membranes, and vacuum extractors consisted of fused-glass air stones attached with airline tubing to 60cc syringes. Centrifugation was accomplished at two speeds (2,500 and 10,000 x g) for 30 min in a refrigerated centrifuge maintained at 4?C. Only minor differences in chemical characteristics and cation and anion concentrations were found among the different collecting methods with differences being sediment specific. Filtering of the pore water did not appreciably reduce major cation concentrations, but trace metals (Cu and Pb) were markedly reduced. Although the extraction methods evaluated produced pore waters of similar chemistries, the vacuum extractor provided the following advantages over the other methods: (1) ease of extraction, (2) volumes of pore water isolated, (3) minimal preparation time and (4) least time required for extraction of pore water from multiple samples at one time.

  14. Electrically tunable pore morphology in nanoporous gold thin films

    Institute of Scientific and Technical Information of China (English)

    Tatiana S. Dorofeeva; Erkin Seker

    2015-01-01

    Nanoporous gold (np-Au) is an emerging nanostructured material that exhibits many desirable properties, including high electrical and thermal conductivity, high surface area-to-volume ratio, tunable pore morphology well-established surface-binding chemistry, and compatibility with microfabrication. These features make np-Au a popular material for use in fuel cells, optical and electrical biosensors, drug delivery vehicles, neural electrode coatings, and as a model system for nanoscale mechanics. In each of its many applications, np-Au morphology plays an essential role in the overall device operation. Therefore, precise morphological control is necessary to attain optimal device performance. Traditionally thermal treatment by furnaces and hot plates is used to obtain np-Au with self-similar but coarser morphologies. However, this approach lacks the ability to create different morphologies on a single substrate and requires high temperatures (〉 250 ℃) incompatible with most plastic substrates. Herein, we report electro-annealing as a novel method that permits control of the extent and location of pore coarsening on a single substrate in one fast treatment step. The electro-annealing entails much lower temperatures (〈 150 ℃) than traditional thermal treatment, putatively due to electrically assisted phenomena contributing to the thermally activated surface diffusion of gold atoms, responsible for coarsening. Overall, this approach is easily scaled to display multiple pore morphologies on a single chip, therefore enabling high-throughput screening of optimal nanostructures for specific applications.

  15. Eleven years' effect of conservation practices for temperate sandy loams: II. Soil pore characteristics

    DEFF Research Database (Denmark)

    Abdollahi, Lotfallah; Munkholm, Lars Juhl

    2017-01-01

    Conservation agriculture (CA) is regarded by many as a sustainable intensification strategy. Minimal soil disturbance in combination with residue retention are important CA components. This study examined the long-term effects of crop rotation, residue retention, and tillage on soil pore characte......Conservation agriculture (CA) is regarded by many as a sustainable intensification strategy. Minimal soil disturbance in combination with residue retention are important CA components. This study examined the long-term effects of crop rotation, residue retention, and tillage on soil pore......, the volume of pores > 30 μm was more than 0.03 m3 m-3 larger for MP than for D in spring 2014 at the 4- to 8-cm depth. At the 18- to 27-cm depth, direct drilling resulted in a better air permeability and pore continuity index (e.g., air permeability of 18.2 and 11.2 mm2 for D and MP, respectively at −10 k...

  16. Nanocasting Process to Pore-Expanded Ordered Mesoporous Carbons with 2D Hexagonal Mesostructure

    Directory of Open Access Journals (Sweden)

    Chongwen Jiang

    2014-01-01

    Full Text Available Pore-expanded ordered mesoporous carbons with 2D hexagonal mesostructure were synthesized by a simple nanocasting process. We adopted sucrose as carbon precursors, mesoporous silica materials SBA-15 as the hard templates, and hexane as micelle swelling agents. The pore size distribution of OMCs was narrow and centered at 5.4 nm, which is larger than the upper limit of pore diameters typically reported for CMK-3. The BET surface area and mesopore volume of PE-CMK-3 can reach to 1213.47 m2/g and 1.56 cm3/g, respectively, indicating that choosing large pore size materials as template is good for preparation of high performance of OMCs.

  17. Monitoring CO2 invasion processes at the pore scale using geological labs on chip.

    Science.gov (United States)

    Morais, S; Liu, N; Diouf, A; Bernard, D; Lecoutre, C; Garrabos, Y; Marre, S

    2016-09-21

    In order to investigate at the pore scale the mechanisms involved during CO2 injection in a water saturated pore network, a series of displacement experiments is reported using high pressure micromodels (geological labs on chip - GLoCs) working under real geological conditions (25 < T (°C) < 75 and 4.5 < p (MPa) < 8). The experiments were focused on the influence of three experimental parameters: (i) the p, T conditions, (ii) the injection flow rates and (iii) the pore network characteristics. By using on-chip optical characterization and imaging approaches, the CO2 saturation curves as a function of either time or the number of pore volume injected were determined. Three main mechanisms were observed during CO2 injection, namely, invasion, percolation and drying, which are discussed in this paper. Interestingly, besides conventional mechanisms, two counterintuitive situations were observed during the invasion and drying processes.

  18. Superficial performance and pore structure of palygorskite treated by hydrochloric acid

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-xin; DAI Wei-wei; Wang Ting; TAO Yong

    2006-01-01

    In order to amend the superficial performance of palygorskite and improve its application, the natural palygorskite(NP) was treated in the dipping and ionic exchanging experiments using 6 mol/L hydrochloric acid treatment. The performance and pore structure of the treated palygorskite(TP) were investigated by means of microscope analyses, FT-IR, XRF, BET-SSA and full hole distribution analytical techniques. The results show that the hydrochloric acid treatment can make the gracile and aggregating compact crystal bundles inside palygorskite clay broken and dispersed, the roughness of microcrystalline surface increases, which not only can dissolve or remove dolomite but vary the superficial performance of palygorskite to some degree. The specific surface area and pore volume increase a lot, while the mean pore size decreases. The pore structure of TP changes remarkably compared with that of NP after 6 mol/L hydrochloric acid treatment, and the relevant physicochemical performance can be improved.

  19. Comparison of caprock pore networks which potentially will be impacted by carbon sequestration projects.

    Energy Technology Data Exchange (ETDEWEB)

    McCray, John (Colorado School of Mines); Navarre-Sitchler, Alexis (Colorado School of Mines); Mouzakis, Katherine (Colorado School of Mines); Heath, Jason E.; Dewers, Thomas A.; Rother, Gernot (Oak Ridge National Laboratory)

    2010-12-01

    Injection of CO2 into underground rock formations can reduce atmospheric CO2 emissions. Caprocks present above potential storage formations are the main structural trap inhibiting CO2 from leaking into overlying aquifers or back to the Earth's surface. Dissolution and precipitation of caprock minerals resulting from reaction with CO2 may alter the pore network where many pores are of the micrometer to nanometer scale, thus altering the structural trapping potential of the caprock. However, the distribution, geometry and volume of pores at these scales are poorly characterized. In order to evaluate the overall risk of leakage of CO2 from storage formations, a first critical step is understanding the distribution and shape of pores in a variety of different caprocks. As the caprock is often comprised of mudstones, we analyzed samples from several mudstone formations with small angle neutron scattering (SANS) and high-resolution transmission electron microscopy (TEM) imaging to compare the pore networks. Mudstones were chosen from current or potential sites for carbon sequestration projects including the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Expandable clay contents ranged from 10% to approximately 40% in the Gothic shale and Kirtland Formation, respectively. During SANS, neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e., minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume and arrangement of pores in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of the pore network. On such plots slopes from -2 to -3 represent mass fractals while slopes from -3 to -4 represent surface fractals. Scattering data showed surface fractal dimensions

  20. Formation and decay of rudimentary penumbra around a pore

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Hiroko [Unit of Synergetic Studies for Space, Kyoto University, Yamashina-ku, Kyoto 607-8417 (Japan); Kitai, Reizaburo [Kwasan and Hida Observatories, Kyoto University, Yamashina-ku, Kyoto 607-8417 (Japan); Otsuji, Kenichi, E-mail: watanabe@kwasan.kyoto-u.ac.jp [Solar Observatory, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan)

    2014-12-01

    We analyze the evolution of a pore in the active region NOAA 10940 using the data obtained by the Hinode satellite on 2007 February 3. The pore we analyzed showed the formation of a rudimentary penumbra structure, succeeded by an abrupt disappearance after about 5 hr. The pore had an approximate radius of 3.5 Mm and a total magnetic flux of 3.0 × 10{sup 19} Mx, which is a little smaller than the necessary magnetic flux for penumbral formation supposed by Rucklidge et al. (1-1.5 × 10{sup 20} Mx). Our observation describes a rare phenomenon which was in the unstable phase between a pore and a sunspot. The area of the dark umbra gradually decreased when the rudimentary penumbral filaments formed the penumbral structure, meaning that the penumbra develops at the expense of the umbral magnetic flux. This statement was confirmed by a rough estimation of the magnetic flux variation observed by the Hinode Fe I magnetogram. Five hours after the formation phase, the decay phase began. In this decaying phase, multiple opposite polarity patches are found to appear in the exterior of the pore (a different location from the penumbra formation site). We interpret these opposite polarities as signatures of the horizontal magnetic field, which preferably appears in the course of the unstable reconfiguration of the magnetic field structure. During the course of the disappearance of the penumbra, the horizontal penumbral field seems to become vertical because of the dark umbral area that recovered by about 10%.

  1. Evolution of Anode Porosity under Air Oxidation: The Unveiling of the Active Pore Size

    Directory of Open Access Journals (Sweden)

    Francois Chevarin

    2017-03-01

    Full Text Available The carbon anode, used in aluminum electrolysis (Hall–Héroult process, is over-consumed by air oxidation and carboxy-reaction (with CO2. Several anode features may affect this over-consumption, such as impurity content, graphitization level and anode porosity features (e.g., porosity volume fraction or pore size distribution. The two first parameters are basically related to the quality of raw materials and coke calcination conditions. Anode porosity is, however, greatly affected by anode manufacturing conditions, and is possible to be modified, to some extent, by adjusting the anode recipe and the processing parameters. This work aims to investigate the effect of anode porosity on its air reactivity. Baked anode samples were prepared in laboratory scale and then crushed into powder form (−4760 + 4000 µm. The recipe for anode preparation was similar to a typical industrial recipe, except that in the lab scale no butt particles were used in the recipe. Anode particles were then gasified at six different conversion levels (0, 5, 15, 25, 35 and 50 wt % under air at 525 °C. The porosity was characterized in several pore size ranges, measured by nitrogen adsorption and mercury intrusion (0.0014–0.020, 0.002–0.025, 0.025–0.100, 0.1–40.0 and superior at 40 µm. The volume variation of each pore range, as a function of carbon conversion, was assessed and used to determine the size of the most active pores for air oxidation. The most active pore size was found to be the pores inferior at 40 µm before 15 wt % of gasification and pores superior at 40 µm between 15 and 50 wt % of carbon conversion. Limitation of pore size range could be used as an additional guideline, along with other targets such as high homogeneity and density, to set the optimum anode manufacturing parameters.

  2. Designing Nonwovens to Meet Pore Size Specifications

    Directory of Open Access Journals (Sweden)

    Glen E. Simmonds

    2007-04-01

    Full Text Available New nonwovens applications in areas such as filtration require a media designed to particular pore size specifications in the 3 to 20 micron range. The purpose of this work was to develop a basis by which to design and construct a fabric with given pore size specifications. While doing so we have provided a validation for two different mathematical models. We have also found that bicomponent spunbonded islands-in-the-sea nonwoven fabrics can be designed very precisely to achieve target pore diameters and porosity. Mathematical models can be used to develop fabric specifications in the standard manufacturing terms of basis weight and fiber diameter. Measured mean flow pore diameters for the test fabrics showed excellent correlation to targeted mean flow pore diameters for both models. The experimental fit to the Bryner model is the better of the two, but requires specification of fabric thickness in addition to basis weight and fiber diameter to achieve actual mean pore diameters that closely match target values. Experimental validation of the influence of fabric thickness on the mean flow pore diameter at constant basis weight and fiber diameter remains open for further investigation. In addition, achieving complete separation of the island and sea polymers along with unbundling of the island fibers remain areas for improvement.

  3. Total protein

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003483.htm Total protein To use the sharing features on this page, please enable JavaScript. The total protein test measures the total amount of two classes ...

  4. Propagation of Love waves in an elastic layer with void pores

    Indian Academy of Sciences (India)

    S Dey; S Gupta; A K Gupta

    2004-08-01

    The paper presents a study of propagation of Love waves in a poroelastic layer resting over a poro-elastic half-space. Pores contain nothing of mechanical or energetic significance. The study reveals that such a medium transmits two types of love waves. The first front depends upon the modulus of rigidity of the elastic matrix of the medium and is the same as the love wave in an elastic layer over an elastic half-space. The second front depends upon the change in volume fraction of the pores. As the first front is well-known, the second front has been investigated numerically for different values of void parameters. It is observed that the second front is many times faster than the shear wave in the void medium due to change in volume fraction of the pores and is significant.

  5. Control of pore size in epoxy systems.

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  6. Analytical applications for pore-forming proteins.

    Science.gov (United States)

    Kasianowicz, John J; Balijepalli, Arvind K; Ettedgui, Jessica; Forstater, Jacob H; Wang, Haiyan; Zhang, Huisheng; Robertson, Joseph W F

    2016-03-01

    Proteinaceous nanometer-scale pores are ubiquitous in biology. The canonical ionic channels (e.g., those that transport Na(+), K(+), Ca(2+), and Cl(-) across cell membranes) play key roles in many cellular processes, including nerve and muscle activity. Another class of channels includes bacterial pore-forming toxins, which disrupt cell function, and can lead to cell death. We describe here the recent development of these toxins for a wide range of biological sensing applications. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.

  7. Pore structure of natural and regenerated soil aggregates

    DEFF Research Database (Denmark)

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

    2014-01-01

    of the soil type and organic matter amendment, and was vastly different from the state of natural aggregates. Aggregate porosity (> 30 Hm) was observed to be a good predictor for the mechanical properties of aggregates. In general, natural aggregates were stronger than lysimeter aggregates.......Quantitative characterization of aggregate pore structure can reveal the evolution of aggregates under different land use and management practices and their effects on soil processes and functions. Advances in X-ray Computed Tomography (CT) provide powerful means to conduct such characterization....... This study examined aggregate pore structure of three differently managed same textured Danish soils (mixed forage cropping, MFC; mixed cash cropping, MCC; cereal cash cropping, CCC) for (i) natural aggregates, and (ii) aggregates regenerated after 20 months of incubation. In total, 27 aggregates (8-16 mm...

  8. Pore Size Distribution of High Performance Metakaolin Concrete

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The Compressive strength, porosity and pore size distribution of high performance metakaolin (MK) concrete were investigated. Concretes containing 0,5%,10% and 20% metakaolin were prepared at a water/cementitious material ratio (W/C) of 0.30. In parallel, concrete mixtures with the replacement of cement by 20% fly ash or 5 and 10% silica fume were prepared for comparison. The specimens were cured in water at 27℃ for 3 to 90 days. The results show that at the early age of curing (3 days and 7 days), metakaolin replacements increase the compressive strength, but silica fume replacement slightly reduces the compressive strength. At the age of and after 28 days, the compressive strength of the concrete with metakaolin and silica fume replacement increases.A strong reduction in the total porosity and average pore diameter were observed in the concrete with MK 20% and 10% in the first 7 days.

  9. Pore structure characterization of Chang-7 tight sandstone using MICP combined with N2GA techniques and its geological control factors

    Science.gov (United States)

    Cao, Zhe; Liu, Guangdi; Zhan, Hongbin; Li, Chaozheng; You, Yuan; Yang, Chengyu; Jiang, Hang

    2016-11-01

    Understanding the pore networks of unconventional tight reservoirs such as tight sandstones and shales is crucial for extracting oil/gas from such reservoirs. Mercury injection capillary pressure (MICP) and N2 gas adsorption (N2GA) are performed to evaluate pore structure of Chang-7 tight sandstone. Thin section observation, scanning electron microscope, grain size analysis, mineral composition analysis, and porosity measurement are applied to investigate geological control factors of pore structure. Grain size is positively correlated with detrital mineral content and grain size standard deviation while negatively related to clay content. Detrital mineral content and grain size are positively correlated with porosity, pore throat radius and withdrawal efficiency and negatively related to capillary pressure and pore-to-throat size ratio; while interstitial material is negatively correlated with above mentioned factors. Well sorted sediments with high debris usually possess strong compaction resistance to preserve original pores. Although many inter-crystalline pores are produced in clay minerals, this type of pores is not the most important contributor to porosity. Besides this, pore shape determined by N2GA hysteresis loop is consistent with SEM observation on clay inter-crystalline pores while BJH pore volume is positively related with clay content, suggesting N2GA is suitable for describing clay inter-crystalline pores in tight sandstones.

  10. Pore structure modification of diatomite as sulfuric acid catalyst support by high energy electron beam irradiation and hydrothermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chong [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Guilong; Wang, Min [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Chen, Jianfeng [Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Cai, Dongqing, E-mail: dqcai@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-08-15

    Highlights: • High energy electron beam (HEEB) irradiation and hydrothermal treatment were used. • HEEB irradiation could make the impurities in the pores of diatomite loose. • Hydrothermal treatment (HT) could remove these impurities from the pores. • They could effectively improve pore size distribution and decrease the bulk density. • Catalytic performance of the corresponding catalyst was significantly improved. - Abstract: High energy electron beam (HEEB) irradiation and hydrothermal treatment (HT), were applied in order to remove the impurities and enlarge the pore size of diatomite, making diatomite more suitable to be a catalyst support. The results demonstrated that, through thermal, charge, impact and etching effects, HEEB irradiation could make the impurities in the pores of diatomite loose and remove some of them. Then HT could remove rest of them from the pores and contribute significantly to the modification of the pore size distribution of diatomite due to thermal expansion, water swelling and thermolysis effects. Moreover, the pore structure modification improved the properties (BET (Brunauer–Emmett–Teller) specific surface area, bulk density and pore volume) of diatomite and the catalytic efficiency of the catalyst prepared from the treated diatomite.

  11. Total Warrant Officer System (TWOS). Volume 1

    Science.gov (United States)

    1985-08-30

    Aviation Center ( ) ... ................... . CbMrAndant, US Army Aviation LogisticsSchool (A2SQ-PN) ....................... 3 Omandant , us m Chemical...Sanborn, Frederick S. CW2 AG ADP Operations Simms, Gary N. CW2 AG Admin. Officer Wirth, Barry 0. CW2 AG USAR Representative Newman, David E. SFC 75Z

  12. Straight Pore Microfilter with Efficient Regeneration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase II project is directed toward development of a novel microfiltration filter that has distinctively narrow pore size...

  13. Straight Pore Microfilter with Efficient Regeneration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project is directed toward development of a novel microfiltration filter that has distinctively narrow pore size...

  14. A Potential Model for Cylindrical Pores

    Institute of Scientific and Technical Information of China (English)

    张现仁; 汪文川

    2001-01-01

    An analytical potential for cylindrical pores has been derived by introducing a variational method into the integration for the calculation of the interaction energy between the wall molecules and a test molecule, all of which are represented by Lennard-Jones potential. The model proposed gives good fit to the results from the cylindrical surface model and the pseudoatom model. To test the potential proposed rigorously, we have carried out grand canonical ensemble Monte Carlo(GCMC) simulation of nitrogen in the MCM-41 pore at 77 K, and compared the simulated adsorption isotherm with the experimental data reported in the literature. The simulated isotherm from our model is in almost qualitative agreement with experiment. Consequently, the model proposed provides an explicit and accurate description of cylindrical pores represented by the Lennard-Jones potential. Moreover, the model can be easily applied to a variety of cylindrical pores, ranging from cylindrical surface to finite thickness walls, in both theoretical studies and computer simulations.

  15. Analysis of a spatially deconvolved solar pore

    CERN Document Server

    Noda, C Quintero; Cobo, B Ruiz; Suematsu, Y; Katsukawa, Y; Ichimoto, K

    2016-01-01

    Solar pores are active regions with large magnetic field strengths and apparent simple magnetic configurations. Their properties resemble the ones found for the sunspot umbra although pores do not show penumbra. Therefore, solar pores present themselves as an intriguing phenomenon that is not completely understood. We examine in this work a solar pore observed with Hinode/SP using two state of the art techniques. The first one is the spatial deconvolution of the spectropolarimetric data that allows removing the stray light contamination induced by the spatial point spread function of the telescope. The second one is the inversion of the Stokes profiles assuming local thermodynamic equilibrium that let us to infer the atmospheric physical parameters. After applying these techniques, we found that the spatial deconvolution method does not introduce artefacts, even at the edges of the magnetic structure, where large horizontal gradients are detected on the atmospheric parameters. Moreover, we also describe the p...

  16. 氮气吸附法表征杨木应拉木的孔隙结构%Pore Structure Characterization of Poplar Tension Wood by Nitrogen Adsorption-Desorption Method

    Institute of Scientific and Technical Information of China (English)

    苌姗姗; 胡进波; Clair Bruno; Quignard Franqoise

    2011-01-01

    Based on the conventional anatomical analysis, the pore structures of poplar tension wood, such as specific surface area, pore volume and pore size distributions were characterized by nitrogen adsorption-desorption method. The shapes of the pores were estimated by nitrogen adsorption isotherms. The results show that poplar tension wood with BET specific surface area of 21. 9 m2 ·g-1, which is 13 times higher than that in opposite wood. Poplar tension wood has intact mesoporosity { pore size between 2-50 nm) with inkbottle and slit shape pore, as well as a certain amount of micropores and macropores. The maximum value of pore size distribution appears at 5 nm. The pore volume with diameter ranging from 4-7 nm makes up 74.4% of the total, and larger than 15 nm, 10. 8% . The high amount of mesopores can be attributed to the thick gelatinous layer in poplar tension wood.%在常规解剖特征分析的基础上,采用氮气吸附法对杨木应拉木的比表面积及孔径分布等孔结构参数进行研究,并通过解析氮气吸附等温线判断孔隙的形状.结果表明:杨木应拉木BET比表面积为21.9 m2·g-1,是对应木的13倍;杨木应拉木试样具有完好的介孔特征(孔径2~50 nm),并具有一定量的微孔和大孔;内部存在“墨水瓶”状和狭缝状孔隙,孔径为5 nm的孔体积分布密度最大,孔径在4~7 nm的孔体积占总孔体积的74.4%,孔径超过15 nm的孔体积占总体积的10.8%.杨木应拉木中大量存在的中孔孔隙可归因于应拉木木纤维中的厚壁胶质层.

  17. Positron lifetimes at the initial stage of pore formation in Vycor glass

    CERN Document Server

    Jasinska, B; Goworek, T

    2000-01-01

    The formation of narrow pores during leaching of Vycor glass by sulphuric acid was investigated using the positron lifetime technique. During the leaching process the pore diameter remained roughly constant (except for the case of cold leaching). The time of processing changed the total length of capillaries, but not their number; at the temperature 50 deg. C during 20 min of leaching the average leaching depth was 24 mu m.

  18. Effects of pore sizes and oxygen-containing functional groups on desulfurization activity of Fe/NAC prepared by ultrasonic-assisted impregnation

    Science.gov (United States)

    Shu, Song; Guo, Jia-Xiu; Liu, Xiao-Li; Wang, Xue-Jiao; Yin, Hua-Qiang; Luo, De-Ming

    2016-01-01

    A series of Fe-loaded activated carbons treated by HNO3 (Fe/NAC) were prepared by incipient impregnation method with or without ultrasonic assistance and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy disperse spectroscope (SEM-EDS), transmission electron microscopy (TEM) and N2 adsorption/desorption. The desulfurization activities were evaluated at a fixed bed reactor under a mixed gas simulated from flue gas. The results showed that desulfurization activity from excellent to poor is as follows: Fe/NAC-60 > Fe/NAC-80 > Fe/NAC-30 > Fe/NAC-15 > Fe/NAC-0 > Fe/NAC-100 > NAC. Fe/NAC-60 exhibits the best desulfurization activity and has breakthrough sulfur capacity of 319 mg/g and breakthrough time of 540 min. The introduction of ultrasonic oscillation does not change the form of Fe oxides on activated carbon but can change the dispersion and relative contents of Fe3O4. The types of oxygen-containing functional groups have no obvious change for all samples but the texture properties show some differences when they are oscillated for different times. The fresh Fe/NAC-60 has a surface area of 1045 m2/g and total pore volume of 0.961 cm3/g with micropore volume of 0.437 cm3/g and is larger than Fe/NAC-0 (823 m2/g, 0.733 and 0.342 cm3/g). After desulfurization, surface area and pore volume of all samples decrease significantly, and those of the exhausted Fe/NAC-60 decrease to 233 m2/g and 0.481 cm3/g, indicating that some byproducts deposit on surface to cover pores. Pore size distribution influences SO2 adsorption, and fresh Fe/NAC-60 has more pore widths centralized at about 0.7 nm and 1.0-2.0 nm and corresponds to an excellent desulfurization activity, showing that micropore is conducive to the removal of SO2.

  19. Visualization of enzyme activities inside earthworm pores

    Science.gov (United States)

    Hoang, Duyen; Razavi, Bahar S.

    2015-04-01

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

  20. Importância das variáveis altura dominante e altura total em equaçõea hipsométricas e volumétricas Importance of the variables dominant height and total height in hipsometric and volumetric equations

    Directory of Open Access Journals (Sweden)

    Helio Garcia Leite

    2003-06-01

    Full Text Available Este estudo foi conduzido, visando avaliar as seguintes hipóteses: a equações hipsométricas devem ser obtidas por parcela, apenas em função do dap; e b equações volumétricas devem ser locais, em função apenas do dap. Foram utilizados dados de quatro parcelas distribuídas ao acaso em um povoamento de eucalipto de 67,81 ha e de 50 parcelas distribuídas ao acaso em um povoamento de 121,3 ha, da mesma espécie. Em uma análise inicial, a fim de obter valores reais de altura total e de volume sólido, realizou-se uma cubagem rigorosa de todas as árvores das quatro parcelas. Foram utilizados, ainda, dados de 277 árvores cubadas rigorosamente nos povoamentos. Para avaliar a exatidão das estimativas e as hipóteses formuladas, empregou-se o procedimento estatístico proposto por Leite & Oliveira (2002. Com base nos resultados, as hipóteses a e b foram rejeitadas a 1% de probabilidade. Concluiu-se, portanto, que em um inventário florestal a variável Hd deve ser considerada e que as equações volumétricas devem ser regionais.This study was carried out to evaluate the following hypotheses: a hipsometric equations should be obtained by plot, only in function of the dbh and b volumetric equations should be local only in function of the dbh. Data of 4 and 50 plots were randomly distributed in a 67.81 ha and 121.3 ha eucalypt stand, respectively. A rigorous scaling of all the trees in the 4 plots was initially carried out to obtain total height and solid volume. Data of 277 trees rigorously scaled in the stand were also used. The statistical procedure proposed by Leite & Oliveira (2002 was used to evaluate the accuracy of the estimates and hypotheses. Based on the results, hypotheses a and b were rejected at 1% probability. It was concluded that, in a forest inventory, the variable dominant height should be considered and the volumetric equations should be regional.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-15

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

  2. Temperature-mediated phase transformation, pore geometry and pore hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders

    Science.gov (United States)

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-05-01

    Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, pore geometry as well as pore hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or pore forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate pore size, pore volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications.

  3. Pore- and micro-structural characterization of a novel structural binder based on iron carbonation

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sumanta, E-mail: Sumanta.Das@asu.edu [School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ (United States); Stone, David, E-mail: dajstone@gmail.com [Iron Shell LLC, Tucson, AZ (United States); Convey, Diana, E-mail: Diana.Convey@asu.edu [LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, AZ (United States); Neithalath, Narayanan, E-mail: Narayanan.Neithalath@asu.edu [School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ (United States)

    2014-12-15

    The pore- and micro-structural features of a novel binding material based on the carbonation of waste metallic iron powder are reported in this paper. The binder contains metallic iron powder as the major ingredient, followed by additives containing silica and alumina to facilitate favorable reaction product formation. Compressive strengths sufficient for a majority of concrete applications are attained. The material pore structure is investigated primarily through mercury intrusion porosimetry whereas electron microscopy is used for microstructural characterization. Reduction in the overall porosity and the average pore size with an increase in carbonation duration from 1 day to 4 days is noticed. The pore structure features are used in predictive models for gas and moisture transport (water vapor diffusivity and moisture permeability) through the porous medium which dictates its long-term durability when used in structural applications. Comparisons of the pore structure with those of a Portland cement paste are also provided. The morphology of the reaction products in the iron-based binder, and the distribution of constituent elements in the microstructure are also reported. - Highlights: • Carbonation of iron produces a dense microstructure. • Pore volume in iron carbonate lower, critical size higher than those in OPC pastes • Reaction product contains iron, carbon, silicon, aluminum and calcium. • Power-law for porosity-moisture permeability relationship was established.

  4. Extreme value statistics analysis of fracture strengths of a sintered silicon nitride failing from pores

    Science.gov (United States)

    Chao, Luen-Yuan; Shetty, Dinesh K.

    1992-01-01

    Statistical analysis and correlation between pore-size distribution and fracture strength distribution using the theory of extreme-value statistics is presented for a sintered silicon nitride. The pore-size distribution on a polished surface of this material was characterized, using an automatic optical image analyzer. The distribution measured on the two-dimensional plane surface was transformed to a population (volume) distribution, using the Schwartz-Saltykov diameter method. The population pore-size distribution and the distribution of the pore size at the fracture origin were correllated by extreme-value statistics. Fracture strength distribution was then predicted from the extreme-value pore-size distribution, usin a linear elastic fracture mechanics model of annular crack around pore and the fracture toughness of the ceramic. The predicted strength distribution was in good agreement with strength measurements in bending. In particular, the extreme-value statistics analysis explained the nonlinear trend in the linearized Weibull plot of measured strengths without postulating a lower-bound strength.

  5. A vacuum-operated pore-water extractor for estuarine and freshwater sediments

    Science.gov (United States)

    Winger, P.V.; Lasier, P.J.

    1991-01-01

    A vacuum-operated pore-water extractor for estuarine and freshwater sediments was developed and constructed from a fused-glass air stone attached with aquarium airline tubing to a 30 or 60 cc polypropylene syringe. Pore water is extracted by inserting the air stone into the sediment and creating a vacuum by retracting and bracing the syringe plunger. A hand-operated vacuum pump attached to a filtration flask was also evaluated as an alternative vacuum source. The volume and time to extract pore water varies with the number of devices and the sediment particle size. Extraction time is longer for fine sediments than for sandy sediments. Four liters of sediment generally yield between 500 and 1,500 mL of pore water. The sediment that surrounds and accumulates on the air stone acts as a filter, and, except for the first few milliliters, the collected pore water is clear. Because there is no exposure to air or avenue for escape, volatile compounds andin situ characteristics are retained in the extracted pore water.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-08-06

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

  7. Total algorithms

    NARCIS (Netherlands)

    Tel, G.

    1993-01-01

    We define the notion of total algorithms for networks of processes. A total algorithm enforces that a "decision" is taken by a subset of the processes, and that participation of all processes is required to reach this decision. Total algorithms are an important building block in the design of distri

  8. Soil Pore Characterization Using Free Software and a Portable Optical Microscope

    Institute of Scientific and Technical Information of China (English)

    L.F.PIRES; F.S.BORGES; S.PASSONI; A.B.PEREIRA

    2013-01-01

    Total porosity (TP),determined by image analysis,pore type and pore size distribution were evaluated on impregnated soil blocks from an undisturbed Brazilian sandy loam soil using a digital portable optical microscope.The free software Image J (version 1.40g) was used for image analysis.Procedures for soil image collection and analysis were presented.The image analysis allowed the evaluation of pore sizes with diameters ranging from 20 to > 1000 μm.The following types of pores were also obtained:rounded,elongated and intermediate.The results allowed the characterization of the soil as moderately porous (TP =21.6%).Rounded,intermediate and elongated pores were responsible for 11.6%,31.7% and 56.7% of TP.In relation to pore size 51.1% of TP was in the 100-500 μm size class and a third of TP came from the pores larger than 500 μm.

  9. Membrane Pore Formation by Amyloid beta (25-35) Peptide

    Science.gov (United States)

    Kandel, Nabin; Tatulian, Suren

    Amyloid (A β) peptide contributes to Alzheimer's disease by a yet unidentified mechanism. One of the possible mechanisms of A β toxicity is formation of pores in cellular membranes. We have characterized the formation of pores in phospholipid membranes by the Aβ25 - 35 peptide (GSNKGAIIGLM) using fluorescence, Fourier transform infrared spectroscopy (FTIR) and circular dichroism (CD) techniques. CD and FTIR identified formation of β-sheet structure upon incubation of the peptide in aqueous buffer for 2 hours. Unilamellar vesicles composed of a zwitterionic lipid, 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), and 70 % POPC plus 30 % of an acidic lipid, 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG), are made in 30 mM CaCl2. Quin-2, a fluorophore that displays increased fluorescence upon Ca2+ binding, is added to the vesicles externally. Peptide addition results in increased Quin-2 fluorescence, which is interpreted by binding of the peptide to the vesicles, pore formation, and Ca2+ leakage. The positive and negative control measurements involve addition of a detergent, Triton X-100, which causes vesicle rupture and release of total calcium, and blank buffer, respectively.

  10. Final Report for Subcontract B541028, Pore-Scale Modeling to Support "Pore Connectivity" Research Work

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R P

    2009-02-25

    This report covers modeling aspects of a combined experimental and modeling task in support of the DOE Science and Technology Program (formerly OSTI) within the Office of Civilian Radioactive Waste Management (OCRWM). Research Objectives The research for this project dealt with diffusive retardation: solute moving through a fracture diffuses into and out of the rock matrix. This diffusive exchange retards overall solute movement, and retardation both dilutes waste being released, and allows additional decay. Diffusive retardation involves not only fracture conductivity and matrix diffusion, but also other issues and processes: contaminants may sorb to the rock matrix, fracture flow may be episodic, a given fracture may or may not flow depending on the volume of flow and the fracture's connection to the overall fracture network, the matrix imbibes water during flow episodes and dries between episodes, and so on. The objective of the project was to improve understanding of diffusive retardation of radionuclides due to fracture / matrix interactions. Results from combined experimental/modeling work were to (1) determine whether the current understanding and model representation of matrix diffusion is valid, (2) provide insights into the upscaling of laboratory-scale diffusion experiments, and (3) help in evaluating the impact on diffusive retardation of episodic fracture flow and pore connectivity in Yucca Mountain tuffs. Questions explored included the following: (1) What is the relationship between the diffusion coefficient measured at one scale, to that measured or observed at a different scale? In classical materials this relationship is trivial; in low-connectivity materials it is not. (2) Is the measured diffusivity insensitive to the shape of the sample? Again, in classical materials there should be no sample shape effect. (3) Does sorption affect diffusive exchange in low-connectivity media differently than in classical media? (4) What is the effect of

  11. Low Pore Connectivity in Natural Rock

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qinhong; Ewing, Robert P.; Dultz, Stefan

    2012-05-15

    As repositories for CO₂ and radioactive waste, as oil and gas reservoirs, and as contaminated sites needing remediation, rock formations play a central role in energy and environmental management. The connectivity of the rock's porespace strongly affects fluid flow and solute transport. This work examines pore connectivity and its implications for fluid flow and chemical transport. Three experimental approaches (imbibition, tracer concentration profiles, and imaging) were used in combination with network modeling. In the imbibition results, three types of imbibition slope [log (cumulative imbibition) vs. log (imbibition time)] were found: the classical 0.5, plus 0.26, and 0.26 transitioning to 0.5. The imbibition slope of 0.26 seen in Indiana sandstone, metagraywacke, and Barnett shale indicates low pore connectivity, in contrast to the slope of 0.5 seen in the well-connected Berea sandstone. In the tracer profile work, rocks exhibited different distances to the plateau porosity, consistent with the pore connectivity from the imbibition tests. Injection of a molten metal into connected pore spaces, followed by 2-D imaging of the solidified alloy in polished thin sections, allowed direct assessment of pore structure and lateral connection in the rock samples. Pore-scale network modeling gave results consistent with measurements, confirming pore connectivity as the underlying cause of both anomalous behaviors: imbibition slope not having the classical value of 0.5, and accessible porosity being a function of distance from the edge. A poorly connected porespace will exhibit anomalous behavior in fluid flow and chemical transport, such as a lower imbibition slope (in air–water system) and diffusion rate than expected from classical behavior.

  12. Low pore connectivity in natural rock.

    Science.gov (United States)

    Hu, Qinhong; Ewing, Robert P; Dultz, Stefan

    2012-05-15

    As repositories for CO(2) and radioactive waste, as oil and gas reservoirs, and as contaminated sites needing remediation, rock formations play a central role in energy and environmental management. The connectivity of the rock's porespace strongly affects fluid flow and solute transport. This work examines pore connectivity and its implications for fluid flow and chemical transport. Three experimental approaches (imbibition, tracer concentration profiles, and imaging) were used in combination with network modeling. In the imbibition results, three types of imbibition slope [log (cumulative imbibition) vs. log (imbibition time)] were found: the classical 0.5, plus 0.26, and 0.26 transitioning to 0.5. The imbibition slope of 0.26 seen in Indiana sandstone, metagraywacke, and Barnett shale indicates low pore connectivity, in contrast to the slope of 0.5 seen in the well-connected Berea sandstone. In the tracer profile work, rocks exhibited different distances to the plateau porosity, consistent with the pore connectivity from the imbibition tests. Injection of a molten metal into connected pore spaces, followed by 2-D imaging of the solidified alloy in polished thin sections, allowed direct assessment of pore structure and lateral connection in the rock samples. Pore-scale network modeling gave results consistent with measurements, confirming pore connectivity as the underlying cause of both anomalous behaviors: imbibition slope not having the classical value of 0.5, and accessible porosity being a function of distance from the edge. A poorly connected porespace will exhibit anomalous behavior in fluid flow and chemical transport, such as a lower imbibition slope (in air-water system) and diffusion rate than expected from classical behavior.

  13. Three-dimensional pore space quantification of apple tissue using X-ray computed microtomography.

    Science.gov (United States)

    Mendoza, Fernando; Verboven, Pieter; Mebatsion, Hibru K; Kerckhofs, Greet; Wevers, Martine; Nicolaï, Bart

    2007-08-01

    The microstructure and the connectivity of the pore space are important variables for better understanding of the complex gas transport phenomena that occur in plant tissues. In this study, we present an experimental procedure for image acquisition and image processing to quantitatively characterize in 3D the pore space of apple tissues (Malus domestica Borkh.) for two cultivars (Jonagold and Braeburn) taken from the fleshy part of the cortex using X-ray computer microtomography. Preliminary sensitivity analyses were performed to determine the effect of the resolution and the volume size (REV, representative elementary volume analysis) on the computed porosity of apple samples. For comparison among cultivars, geometrical properties such as porosity, specific surface area, number of disconnected pore volumes and their distribution parameters were extracted and analyzed in triplicate based on the 3D skeletonization of the pore space (medial axis analysis). The results showed that microtomography provides a resolution at the micrometer level to quantitatively analyze and characterize the 3D topology of the pore space in apple tissue. The computed porosity was confirmed to be highly dependent of the resolution used, and the minimum REV of the cortical flesh of apple fruit was estimated to be 1.3 mm(3). Comparisons among the two cultivars using a resolution of 8.5 mum with a minimum REV cube showed that in spite of the complexity and variability of the pore space network observed in Jonagold and Braeburn apples, the extracted parameters from the medial axis were significantly different (P-value < 0.05). Medial axis parameters showed potential to differentiate the microstructure between the two evaluated apple cultivars.

  14. Pore Structure Characterization of Indiana Limestone and Pink Dolomite from Pore Network Reconstructions

    Directory of Open Access Journals (Sweden)

    Freire-Gormaly Marina

    2016-05-01

    Full Text Available Carbon sequestration in deep underground saline aquifers holds significant promise for reducing atmospheric carbon dioxide emissions (CO2. However, challenges remain in predicting the long term migration of injected CO2. Addressing these challenges requires an understanding of pore-scale transport of CO2 within existing brine-filled geological reservoirs. Studies on the transport of fluids through geological porous media have predominantly focused on oil-bearing formations such as sandstone. However, few studies have considered pore-scale transport within limestone and other carbonate formations, which are found in potential storage sites. In this work, high-resolution micro-Computed Tomography (microCT was used to obtain pore-scale structural information of two model carbonates: Indiana Limestone and Pink Dolomite. A modified watershed algorithm was applied to extract pore network from the reconstructed microCT volumetric images of rock samples and compile a list of pore-scale characteristics from the extracted networks. These include statistical distributions of pore size and radius, pore-pore separation, throat radius, and network coordination. Finally, invasion percolation algorithms were applied to determine saturation-pressure curves for the rock samples. The statistical distributions were comparable to literature values for the Indiana Limestone. This served as validation for the network extraction approach for Pink Dolomite, which has not been considered previously. Based on the connectivity and the pore-pore separation, formations such as Pink Dolomite may present suitable storage sites for carbon storage. The pore structural distributions and saturation curves obtained in this study can be used to inform core- and reservoir-scale modeling and experimental studies of sequestration feasibility.

  15. International Prostatic Symptom Score-voiding/storage subscore ratio in association with total prostatic volume and maximum flow rate is diagnostic of bladder outlet-related lower urinary tract dysfunction in men with lower urinary tract symptoms.

    Directory of Open Access Journals (Sweden)

    Yuan-Hong Jiang

    Full Text Available OBJECTIVES: The aim of this study was to investigate the predictive values of the total International Prostate Symptom Score (IPSS-T and voiding to storage subscore ratio (IPSS-V/S in association with total prostate volume (TPV and maximum urinary flow rate (Qmax in the diagnosis of bladder outlet-related lower urinary tract dysfunction (LUTD in men with lower urinary tract symptoms (LUTS. METHODS: A total of 298 men with LUTS were enrolled. Video-urodynamic studies were used to determine the causes of LUTS. Differences in IPSS-T, IPSS-V/S ratio, TPV and Qmax between patients with bladder outlet-related LUTD and bladder-related LUTD were analyzed. The positive and negative predictive values (PPV and NPV for bladder outlet-related LUTD were calculated using these parameters. RESULTS: Of the 298 men, bladder outlet-related LUTD was diagnosed in 167 (56%. We found that IPSS-V/S ratio was significantly higher among those patients with bladder outlet-related LUTD than patients with bladder-related LUTD (2.28±2.25 vs. 0.90±0.88, p1 or >2 was factored into the equation instead of IPSS-T, PPV were 91.4% and 97.3%, respectively, and NPV were 54.8% and 49.8%, respectively. CONCLUSIONS: Combination of IPSS-T with TPV and Qmax increases the PPV of bladder outlet-related LUTD. Furthermore, including IPSS-V/S>1 or >2 into the equation results in a higher PPV than IPSS-T. IPSS-V/S>1 is a stronger predictor of bladder outlet-related LUTD than IPSS-T.

  16. Pore Distribution and Water Uptake in a Cenosphere-Cement Paste Composite Material

    Science.gov (United States)

    Baronins, J.; Setina, J.; Sahmenko, G.; Lagzdina, S.; Shishkin, A.

    2015-11-01

    Alumina silicate cenospheres (CS) is a significant waste material from power plants that use a coal. Use CS as Portland cement replacement material gives opportunity to control physical and mechanical properties and makes a product lighter and more cost-effective. In the frame of this study, Portland cement paste samples were produced by adding CS in the concentration range from 0 to 40 volume %. Water uptake of hardened samples was checked and pore size distribution by using the mercury porosimetry was determined. In a cold climate where the temperature often falls below 0 °C, it is important to avoid the amount of micrometer sized pores in the final structure and to decrease water absorption capacity of material. In winter conditions, water fills such pores and causes additional stresses to their walls by expansion while freezing. It was found that generally water uptake capacity for cement paste samples decreased up to 20% by increasing the concentration of CS up to 40 volume %, at the same time, the volume of micrometer sized opened pores increases.

  17. Modeling branching pore structures in membrane filters

    Science.gov (United States)

    Sanaei, Pejman; Cummings, Linda J.

    2016-11-01

    Membrane filters are in widespread industrial use, and mathematical models to predict their efficacy are potentially very useful, as such models can suggest design modifications to improve filter performance and lifetime. Many models have been proposed to describe particle capture by membrane filters and the associated fluid dynamics, but most such models are based on a very simple structure in which the pores of the membrane are assumed to be simple circularly-cylindrical tubes spanning the depth of the membrane. Real membranes used in applications usually have much more complex geometry, with interconnected pores which may branch and bifurcate. Pores are also typically larger on the upstream side of the membrane than on the downstream side. We present an idealized mathematical model, in which a membrane consists of a series of bifurcating pores, which decrease in size as the membrane is traversed. Feed solution is forced through the membrane by applied pressure, and particles are removed from the feed either by sieving, or by particle adsorption within pores (which shrinks them). Thus the membrane's permeability decreases as the filtration progresses, ultimately falling to zero. We discuss how filtration efficiency depends on the characteristics of the branching structure. Partial support from NSF DMS 1261596 is gratefully acknowledged.

  18. Performance of Small Pore Microchannel Plates

    Science.gov (United States)

    Siegmund, O. H. W.; Gummin, M. A.; Ravinett, T.; Jelinsky, S. R.; Edgar, M.

    1995-01-01

    Small pore size microchannel plates (MCP's) are needed to satisfy the requirements for future high resolution small and large format detectors for astronomy. MCP's with pore sizes in the range 5 micron to 8 micron are now being manufactured, but they are of limited availability and are of small size. We have obtained sets of Galileo 8 micron and 6.5 micron MCP's, and Philips 6 micron and 7 micron pore MCP's, and compared them to our larger pore MCP Z stacks. We have tested back to back MCP stacks of four of these MCP's and achieved gains greater than 2 x 1O(exp 7) with pulse height distributions of less than 40% FWHM, and background rates of less than 0.3 events sec(exp -1) cm(exp -2). Local counting rates up to approx. 100 events/pore/sec have been attained with little drop of the MCP gain. The bare MCP quantum efficiencies are somewhat lower than those expected, however. Flat field images are characterized by an absence of MCP fixed pattern noise.

  19. Modeling Tissue Growth Within Nonwoven Scaffolds Pores

    Science.gov (United States)

    Church, Jeffrey S.; Alexander, David L.J.; Russell, Stephen J.; Ingham, Eileen; Ramshaw, John A.M.; Werkmeister, Jerome A.

    2011-01-01

    In this study we present a novel approach for predicting tissue growth within the pores of fibrous tissue engineering scaffolds. Thin nonwoven polyethylene terephthalate scaffolds were prepared to characterize tissue growth within scaffold pores, by mouse NR6 fibroblast cells. On the basis of measurements of tissue lengths at fiber crossovers and along fiber segments, mathematical models were determined during the proliferative phase of cell growth. Tissue growth at fiber crossovers decreased with increasing interfiber angle, with exponential relationships determined on day 6 and 10 of culture. Analysis of tissue growth along fiber segments determined two growth profiles, one with enhanced growth as a result of increased tissue lengths near the fiber crossover, achieved in the latter stage of culture. Derived mathematical models were used in the development of a software program to visualize predicted tissue growth within a pore. This study identifies key pore parameters that contribute toward tissue growth, and suggests models for predicting this growth, based on fibroblast cells. Such models may be used in aiding scaffold design, for optimum pore infiltration during the tissue engineering process. PMID:20687775

  20. Analysis of a spatially deconvolved solar pore

    Science.gov (United States)

    Quintero Noda, C.; Shimizu, T.; Ruiz Cobo, B.; Suematsu, Y.; Katsukawa, Y.; Ichimoto, K.

    2016-08-01

    Solar pores are active regions with large magnetic field strengths and apparent simple magnetic configurations. Their properties resemble the ones found for the sunspot umbra although pores do not show penumbra. Therefore, solar pores present themselves as an intriguing phenomenon that is not completely understood. We examine in this work a solar pore observed with Hinode/SP using two state of the art techniques. The first one is the spatial deconvolution of the spectropolarimetric data that allows removing the stray light contamination induced by the spatial point spread function of the telescope. The second one is the inversion of the Stokes profiles assuming local thermodynamic equilibrium that let us to infer the atmospheric physical parameters. After applying these techniques, we found that the spatial deconvolution method does not introduce artefacts, even at the edges of the magnetic structure, where large horizontal gradients are detected on the atmospheric parameters. Moreover, we also describe the physical properties of the magnetic structure at different heights finding that, in the inner part of the solar pore, the temperature is lower than outside, the magnetic field strength is larger than 2 kG and unipolar, and the line-of-sight velocity is almost null. At neighbouring pixels, we found low magnetic field strengths of same polarity and strong downward motions that only occur at the low photosphere, below the continuum optical depth log τ = -1. Finally, we studied the spatial relation between different atmospheric parameters at different heights corroborating the physical properties described before.

  1. Pore Pressure Under A Gravity Based Structure Under The Influence Of Waves

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Carstensen, Stefan; Madsen, Mikael Thyge

    2017-01-01

    The total wave load on a gravity based foundation for offshore wind turbines is influenced by the pore pressure from beneath the structure. The pore pressure is induced by the wave–structure-seabed interaction. Often the uplift force is included in a simplified way in the design of the gravity ba...... analyses, it was possible to investigate the effect of air content in the pores, which turned out to have an effect on the distribution of the pore pressure.......The total wave load on a gravity based foundation for offshore wind turbines is influenced by the pore pressure from beneath the structure. The pore pressure is induced by the wave–structure-seabed interaction. Often the uplift force is included in a simplified way in the design of the gravity...... based foundation. This leads typically to very conservative designs in order to accommodate the uncertainties in the procedure. The experiments shall lead to better prediction models based on for instance CFD model’s with the direct calculation of pressure variations in the seabed and any erosion...

  2. 免疫性炎症与前列腺体积及雄激素受体表达的关系%Correlations of Immune Inflammation with Total Prostate Volume and Androgen Receptor Expression

    Institute of Scientific and Technical Information of China (English)

    吴宗林; 袁亚; 耿和; 夏术阶

    2011-01-01

    目的:探讨免疫性炎症与前列腺体积及雄激素受体表达的关系.方法:回顾性的分析了105例手术获得的前列腺标本.使用免疫组化的方法研究前列腺组织中CD4、CD8和雄激素受体表达情况.如果CD4或CD8阳性则被定义为免疫性炎症,并进一步探讨了免疫性炎症与前列腺体积、雄激素受体表达之间的关系.结果:在前列腺增生组织中,CD4、CD8和雄激素受体表达的阳性率分别为20(19.0%),21(20.0%)和48(45.7%).在免疫性炎症组,前列腺体积为67.0±26.3ml,而在非免疫性炎症组,为54.0±24.2ml,有显著性差别.免疫性炎症组雄激素受体表达的阳性率为65.6%,而非免疫性炎症组雄激素受体表达的阳性率为37.0%(x=7.35,P<0.05).结论:免疫性炎症与前列腺体积、雄激素受体表达明显相关.免疫性炎症可能导致前列腺增生进展,因此,抗炎治疗可能是治疗前列腺增生的一个新的靶点.%Objectives: To investigate the association of immune inflammation with total prostate volume and androgen receptor expression in benign prostatic hyperplasia (BPH). Methods: One hundred and five surgery-derived prostate specimens were analyzed retrospectively. Immune inflammation was defined by CD4 or CD8 marker positive expression on immunohistochemistry (MC). IHC markers were CD4 and CD8 decorating T-lymphocytes, and androgen receptor (AR) antibody decorating androgen receptor in BPH samples. Total prostate volumes (TPV) and AR expression associated with immune inflammation were analyzed. Results: The rate of CD4, CD8 and AR expression in BPH was 20 (19.0%), 21 (20.0%) and 48 (45.7%), respectively. Total prostate volume was significantly higher in the immune inflammation group compared to the non-immune inflammation group (67.0 cm3 vs. 54 cm3; t=2.32, P<0.05). There was a significant difference in AR expression between immune inflammation group and non-immune inflammation group ( X2=7.35, P<0. 05). The rate of

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

    Directory of Open Access Journals (Sweden)

    Hui-Jun Yi

    2016-10-01

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

  4. Chromatographic performance of large-pore versus small-pore columns in micellar liquid chromatography.

    Science.gov (United States)

    McCormick, Timothy J; Foley, Joe P; Lloyd, David K

    2003-02-25

    Micellar liquid chromatography (MLC) is useful in bioanalysis because proteinaceous biofluids can be directly injected onto the column. The technique has been limited in part because of the apparently weak eluting power of micellar mobile phases. It has recently been shown [Anal. Chem. 72 (2000) 294] that this may be overcome by the use of large pore size stationary phases. In this work, large-pore (1000 A) C(18) stationary phases were evaluated relative to conventional small-pore (100 A) C(18) stationary phases for the direct sample injection of drugs in plasma. Furthermore, the difference between the large and small pore phases in gradient elution separations of mixtures of widely varying hydrophobicities was investigated. Large-pore stationary phases were found to be very effective for eluting moderately to highly hydrophobic compounds such as ibuprofen, crotamiton, propranolol, and dodecanophenone, which were highly retained on the small-pore stationary phases typically used in MLC. The advantages of direct introduction of biological samples (drugs in plasma) and rapid column re-equilibration after gradient elution in MLC were maintained with large-pore phases. Finally, recoveries, precision, linearity, and detection limits for the determination of quinidine and DPC 961 in spiked bovine plasma were somewhat better using MLC with wide pore phases.

  5. Modeling of N2 adsorption in MCM-41 materials: hexagonal pores versus cylindrical pores.

    Science.gov (United States)

    Ustinov, Eugene A

    2009-07-07

    Low-temperature nitrogen adsorption in hexagonal pores and equivalent cylindrical pores is analyzed using nonlocal density functional theory extended to amorphous solids (NLDFT-AS). It is found that, despite significant difference of the density distribution over the cross-section of the pore, the capillary condensation/evaporation pressure is not considerably affected by the pore shape being slightly lower in the case of hexagonal geometry. However, the condensation/evaporation step in the hexagonal pore is slightly larger than that in the equivalent cylindrical pore because in the latter case the pore wall surface area and, hence, the amount adsorbed at pressures below the evaporation pressure are underestimated by 5%. We show that a dimensionless parameter defined as the ratio of the condensation/evaporation step and the upper value of the amount adsorbed at the condensation/evaporation pressure can be used as an additional criterion of the correct choice of the gas-solid molecular parameters along with the dependence of condensation/evaporation pressure on the pore diameter. Application of the criteria to experimental data on nitrogen adsorption on a series of MCM-41 silica at 77 K corroborates some evidence that the capillary condensation occurs at equilibrium conditions.

  6. Geochemistry of Clayey Aquitard Pore Water as Archive of Paleo-Environment, Western Bohai Bay

    Institute of Scientific and Technical Information of China (English)

    Jing Li; Xing Liang; Menggui Jin; Guoqiang Xiao; Jishan He; Yandong Pei

    2015-01-01

    The record of paleo-environment in clayey aquitard pore water is much more effective relative to aquifer groundwater owing to the low permeability of clayey aquitard. Oxygen-18 (18O), deuterium (D), and chemical patterns were determined in pore water samples extracted from two 500 m depth boreholes, G1 and G2, in western Bohai Bay, China. Shallow pore water samples (depth<102 m) are saline water, with the TDS (total dissolved solids) of 3.69–30.75 g/L, and deeper ones (depth=102–500 m) are fresh water, with the TDS<1 g/L. Content of major ions (i.e., Cl-, Na+, K+, Mg2+, SO42-, Ca2+) is high in marine sediment pore water samples and gradually decrease towards to terre-strial sediment pore water, together with the Cl/Br and Sr/Ba ratios changing significantly in different sedimentary facies along the study profile, indicating that pore water may be paleo-sedimentary water and not replaced by modern water.δ18O profile and positive correlation betweenδ18O and Cl-of shal-low saline pore water indicated diffusion as the main transport mechanism, and distinguished four transgressive layers since Late Quaternary (i.e., Holocene marine unit, two Late Pleistocene marine units and Middle Pleistocene marine unit), further supporting the finding that pore water retained the feature of paleo-sedimentary water. Climate was identified as the main influence on the isotopic signa-ture of aquitard pore water and four climate periods were determined byδ18O profile.

  7. Study on lotus-type porous copper electroplated with a Ni coating on inner surface of pores

    Science.gov (United States)

    Du, Hao; Song, Guihong; Nakajima, Hideo; Zhao, Yanhui; Xiao, Jinquan; Xiong, Tianying

    2013-01-01

    Deposition of Ni coating on inner surface of pores was attempted by electroplating for lotus-type porous copper with pore size of 0.6 mm and pore length of 6 mm. The surface morphology, thickness, thickness distribution along the pore length, and phase composition of the coating were characterized. It is proven that the Ni coating with a polycrystalline structure can be deposited on the inner surface of the pores with length/diameter of 10 for lotus-type porous copper by agitating the electroplating solution properly during the process. It is indicated that the coating thickness distributes uniformly along the pore depth and is about 4-5 μm. Furthermore, the mechanical properties including vicker hardness, compressive yield strength and absorbed energy ability of the electroplated porous copper were evaluated. It is found that the mechanical properties are improved significantly after depositing the nickel coating inside pores of the lotus-type porous copper. Among them, 0.2% yield stress increases from 22.96 to 30.15 MPa, while absorbed energy per volume from 60.83 to 96.01 MJ/m3 when compressed to strain of 80%, which is attributed mainly to the Ni coating as an obstacle to dislocation slip during deformation and its strengthening effect for the higher strength, and the good adhesion to the pore wall of the porous copper.

  8. Moving Magnetic Features around a Pore

    CERN Document Server

    Kaithakkal, A J; Solanki, S K; Lagg, A; Barthol, P; Gandorfer, A; Gizon, L; Hirzberger, J; vanNoort, M; Rodríguez, J Blanco; Iniesta, J C Del Toro; Suárez, D Orozco; Schmidt, W; Pillet, V Martínez; Knölker, M

    2016-01-01

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

  9. Optical detection of pores in adipocyte membrane

    Science.gov (United States)

    Yanina, I. Yu.; Doubrovski, V. A.; Tuchin, V. V.

    2013-08-01

    Structures that can be interpreted as cytoplasm droplets leaking through the membrane are experimentally detected on the membranes of adipocytes using optical digital microscopy. The effect of an aqueous alcohol solution of brilliant green on the amount and sizes of structures is studied. It is demonstrated that the optical irradiation of the adipocytes that are sensitized with the aid of the brilliant green leads to an increase in the amount of structures (pores) after the irradiation. The experimental results confirm the existence of an earlier-proposed effect of photochemical action on the sensitized cells of adipose tissue that involves additional formation of pores in the membrane of the sensitized cell under selective optical irradiation. The proposed method for the detection of micropores in the membrane of adipose tissue based on the detection of the cytoplasm droplets leaking from the cell can be considered as a method for the optical detection of nanosized pores.

  10. Volumes and surface areas of pendular rings

    Science.gov (United States)

    Rose, W.

    1958-01-01

    A packing of spheres is taken as a suitable model of porous media. The packing may be regular and the sphere size may be uniform, but in general, both should be random. Approximations are developed to give the volumes and surface areas of pendular rings that exist at points of sphere contact. From these, the total free volume and interfacial specific surface area are derived as expressive of the textural character of the packing. It was found that the log-log plot of volumes and surface areas of pendular rings vary linearly with the angle made by the line joining the sphere centers and the line from the center of the largest sphere to the closest edge of the pendular ring. The relationship, moreover, was found not to be very sensitive to variation in the size ratio of the spheres in contact. It also was found that the addition of pendular ring material to various sphere packings results in an unexpected decrease in the surface area of the boundaries that confine the resulting pore space. ?? 1958 The American Institute of Physics.

  11. Association of Habitual Patterns and Types of Physical Activity and Inactivity with MRI-Determined Total Volumes of Visceral and Subcutaneous Abdominal Adipose Tissue in a General White Population.

    Directory of Open Access Journals (Sweden)

    Karina Fischer

    Full Text Available Population-based evidence for the role of habitual physical activity (PA in the accumulation of visceral (VAT and subcutaneous (SAAT abdominal adipose tissue is limited. We investigated if usual patterns and types of self-reported PA and inactivity were associated with VAT and SAAT in a general white population. Total volumes of VAT and SAAT were quantified by magnetic resonance imaging in 583 men and women (61 ± 11.9 y; BMI 27.2 ± 4.4 kg/m2. Past-year PA and inactivity were self-reported by questionnaire. Exploratory activity patterns (APAT were derived by principal components analysis. Cross-sectional associations between individual activities, total PA in terms of metabolic equivalents (PA MET, or overall APAT and either VAT or SAAT were analyzed by multivariable-adjusted robust or generalized linear regression models. Whereas vigorous-intensity PA (VPA was negatively associated with both VAT and SAAT, associations between total PA MET, moderate-intensity PA (MPA, or inactivity and VAT and/or SAAT depended on sex. There was also evidence of a threshold effect in some of these relationships. Total PA MET was more strongly associated with VAT in men (B = -3.3 ± 1.4; P = 0.02 than women (B = -2.1 ± 1.1; P = 0.07, but was more strongly associated with SAAT in women (B = -5.7 ± 2.5; P = 0.05 than men (B = -1.7 ± 1.6; P = 0.3. Men (-1.52 dm3 or -1.89 dm3 and women (-1.15 dm3 or -2.61 dm3 in the highest (>6.8 h/wk VPA or second (4.0-6.8 h/wk VPA tertile of an APAT rich in VPA, had lower VAT and SAAT, respectively, than those in the lowest (<4.0 h/wk VPA tertile (P ≤ 0.016; P trend ≤ 0.0005. They also had lower VAT and SAAT than those with APAT rich in MPA and/or inactivity only. In conclusion, our results suggest that in white populations, habitual APAT rich in MPA might be insufficient to impact on accumulation of VAT or SAAT. APAT including ≥ 4.0-6.8 h/wk VPA, by contrast, are more strongly associated with lower VAT and SAAT.

  12. Association of Habitual Patterns and Types of Physical Activity and Inactivity with MRI-Determined Total Volumes of Visceral and Subcutaneous Abdominal Adipose Tissue in a General White Population.

    Science.gov (United States)

    Fischer, Karina; Rüttgers, Daniela; Müller, Hans-Peter; Jacobs, Gunnar; Kassubek, Jan; Lieb, Wolfgang; Nöthlings, Ute

    2015-01-01

    Population-based evidence for the role of habitual physical activity (PA) in the accumulation of visceral (VAT) and subcutaneous (SAAT) abdominal adipose tissue is limited. We investigated if usual patterns and types of self-reported PA and inactivity were associated with VAT and SAAT in a general white population. Total volumes of VAT and SAAT were quantified by magnetic resonance imaging in 583 men and women (61 ± 11.9 y; BMI 27.2 ± 4.4 kg/m2). Past-year PA and inactivity were self-reported by questionnaire. Exploratory activity patterns (APAT) were derived by principal components analysis. Cross-sectional associations between individual activities, total PA in terms of metabolic equivalents (PA MET), or overall APAT and either VAT or SAAT were analyzed by multivariable-adjusted robust or generalized linear regression models. Whereas vigorous-intensity PA (VPA) was negatively associated with both VAT and SAAT, associations between total PA MET, moderate-intensity PA (MPA), or inactivity and VAT and/or SAAT depended on sex. There was also evidence of a threshold effect in some of these relationships. Total PA MET was more strongly associated with VAT in men (B = -3.3 ± 1.4; P = 0.02) than women (B = -2.1 ± 1.1; P = 0.07), but was more strongly associated with SAAT in women (B = -5.7 ± 2.5; P = 0.05) than men (B = -1.7 ± 1.6; P = 0.3). Men (-1.52 dm3 or -1.89 dm3) and women (-1.15 dm3 or -2.61 dm3) in the highest (>6.8 h/wk VPA) or second (4.0-6.8 h/wk VPA) tertile of an APAT rich in VPA, had lower VAT and SAAT, respectively, than those in the lowest (<4.0 h/wk VPA) tertile (P ≤ 0.016; P trend ≤ 0.0005). They also had lower VAT and SAAT than those with APAT rich in MPA and/or inactivity only. In conclusion, our results suggest that in white populations, habitual APAT rich in MPA might be insufficient to impact on accumulation of VAT or SAAT. APAT including ≥ 4.0-6.8 h/wk VPA, by contrast, are more strongly associated with lower VAT and SAAT.

  13. Pore Pressure Measurements Inside Rubble Mound Breakwaters

    DEFF Research Database (Denmark)

    Helgason, Einar; Burcharth, H. F.; Grüne, Joachim

    2004-01-01

    The present paper presents pore pressure measurements from large scale model tests performed at the Large Wave Channel, Hannover, Germany and small scale model test performed at the Hydraulic & Coastal Engineering Laboratory, Aalborg University, Denmark. Information on pore pressure attenuation......, and compared to a damping model presented by Burcharth et al. (1999). Reasonable agreement is found when considering the difference in the grading and uniformity of the model core materials. Comparison between results obtained from small and large scale model tests showed no clear evidence of scale effects....

  14. Porous media fluid transport and pore structure

    CERN Document Server

    Dullien, F A L

    1992-01-01

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

  15. Simultaneous determination of the Cd and Zn total body burden of individual, nearly microscopic, nanoliter-volume aquatic organisms (Hyalella azteca) by rhenium-cup in-torch vaporization (ITV) sample introduction and axially viewed ICP-AES

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Andrea T.; Badiei, Hamid R.; Karanassios, Vassili [University of Waterloo, Department of Chemistry, Waterloo, ON (Canada); Evans, J. Catherine [University of Waterloo, Department of Biology, Waterloo, ON (Canada)

    2004-09-01

    The Cd and Zn total body burden of individual, up to 7-day-old aquatic organisms (Hyalella aztecabenthic amphipod) with an average volume of approximately 100 nL was determined simultaneously by using rhenium-cup (Re-cup) in-torch vaporization (ITV) sample introduction and an axially viewed inductively coupled plasma atomic emission spectrometry (ICP-AES) system. The direct elemental analysis capabilities of this system (i.e., no sample digestion) reduced sample preparation time, eliminated contamination concerns from the digestion reagent and, owing to its detection limits (e.g., in the low pg range for Cd and Zn), vit enabled simultaneous determinations of Cd and Zn in individual, neonate and young juvenile specimens barely visible to the unaided eye (e.g., nearly microscopic). As for calibration, liquid standards and the standard additions method were tested. Both methods gave comparable results, thus indicating that in this case liquid standards can be employed for calibration, and in the process making use of the standard additions method unnecessary. Overall, the ITV-ICP-AES approach by-passed the time-consuming acid digestions, eliminated the potential for contamination from the digestion reagents, improved considerably the speed of acquisition of analytical information and enabled simultaneous determinations of two elements using individual biological specimens. (orig.)

  16. Influence of pore size distribution on the adsorption of phenol on PET-based activated carbons.

    Science.gov (United States)

    Lorenc-Grabowska, Ewa; Diez, María A; Gryglewicz, Grazyna

    2016-05-01

    The role of pore size distribution in the adsorption of phenol in aqueous solutions on polyethylene terephthalate (PET)-based activated carbons (ACs) has been analyzed. The ACs were prepared from PET and mixtures of PET with coal-tar pitch (CTP) by means of carbonization and subsequent steam and carbon dioxide activation at 850 and 950 °C, respectively. The resultant ACs were characterized on the basis of similarities in their surface chemical features and differences in their micropore size distributions. The adsorption of phenol was carried out in static conditions at ambient temperature. The pseudo-second order kinetic model and Langmuir model were found to fit the experimental data very well. The different adsorption capacities of the ACs towards phenol were attributed to differences in their micropore size distributions. Adsorption capacity was favoured by the volume of pores with a size smaller than 1.4 nm; but restricted by pores smaller than 0.8 nm.

  17. Controlling Pore Size and its Distribution of γ-Al2O3 Nanofiltration Membranes

    Institute of Scientific and Technical Information of China (English)

    Rong Chun XIONG; Xiao Dong LEI; Gang WEI

    2003-01-01

    The preparation process of γ-Al2O3 nanofiltration membranes were studied by N2absorption and desorption test and retention rate vs thickness gradient curve method. It was foundthat template and thermal treatment were key factors for controlling pore size and its distribution.Under the optimized experimental conditions, the BJH (Barret-Joyner-Halenda) desorption averagepore diameter, BJH desorption cumulative volume of pores and BET (Brunauer-Emmett-Teller)surface area of obtained membranes were about 3.9 nm, 0.33 cm3/g and 245 m2/g respectively, thepore size distribution was very narrow. Pore size decreased with the increasing of thickness andno evident change after the dense top layer was formed. The optimum thickness can becontrolled by retention rate vs thickness gradient curve method.

  18. Accurate and efficient maximal ball algorithm for pore network extraction

    Science.gov (United States)

    Arand, Frederick; Hesser, Jürgen

    2017-04-01

    The maximal ball (MB) algorithm is a well established method for the morphological analysis of porous media. It extracts a network of pores and throats from volumetric data. This paper describes structural modifications to the algorithm, while the basic concepts are preserved. Substantial improvements to accuracy and efficiency are achieved as follows: First, all calculations are performed on a subvoxel accurate distance field, and no approximations to discretize balls are made. Second, data structures are simplified to keep memory usage low and improve algorithmic speed. Third, small and reasonable adjustments increase speed significantly. In volumes with high porosity, memory usage is improved compared to classic MB algorithms. Furthermore, processing is accelerated more than three times. Finally, the modified MB algorithm is verified by extracting several network properties from reference as well as real data sets. Runtimes are measured and compared to literature.

  19. Pore Fluid Effects on Shear Modulus in a Model of Heterogeneous Rocks, Reservoirs, and Granular Media

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J G

    2005-03-23

    To provide quantitative measures of the importance of fluid effects on shear waves in heterogeneous reservoirs, a model material called a ''random polycrystal of porous laminates'' is introduced. This model poroelastic material has constituent grains that are layered (or laminated), and each layer is an isotropic, microhomogeneous porous medium. All grains are composed of exactly the same porous constituents, and have the same relative volume fractions. The order of lamination is not important because the up-scaling method used to determine the transversely isotropic (hexagonal) properties of the grains is Backus averaging, which--for quasi-static or long-wavelength behavior--depends only on the volume fractions and layer properties. Grains are then jumbled together totally at random, filling all space, and producing an overall isotropic poroelastic medium. The poroelastic behavior of this medium is then analyzed using the Peselnick-Meister-Watt bounds (of Hashin-Shtrikman type). We study the dependence of the shear modulus on pore fluid properties and determine the range of behavior to be expected. In particular we compare and contrast these results to those anticipated from Gassmann's fluid substitution formulas, and to the predictions of Mavko and Jizba for very low porosity rocks with flat cracks. This approach also permits the study of arbitrary numbers of constituents, but for simplicity the numerical examples are restricted here to just two constituents. This restriction also permits the use of some special exact results available for computing the overall effective stress coefficient in any two-component porous medium. The bounds making use of polycrystalline microstructure are very tight. Results for the shear modulus demonstrate that the ratio of compliance differences R (i.e., shear compliance changes over bulk compliance changes when going from drained to undrained behavior, or vice versa) is usually nonzero and can take a wide

  20. Experimental Investigation of the Variation of Concrete Pores under the Action of Freeze-Thaw Cycles by Using X-Ray CT

    Directory of Open Access Journals (Sweden)

    Jie Yuan

    2014-01-01

    Full Text Available The variation of concrete pores under the action of freeze-thaw cycles was investigated experimentally by using the X-ray CT. Firstly, the statistical characteristics of pores of concrete specimens were obtained by using the X-ray image analysis. Secondly, the variation of porosity and pore volume of concrete pores were analyzed and discussed by comparing with above characteristics. Thirdly, the failure process of the concrete specimens acted by the freeze-thaw cycles was investigated by scanning the interior of concrete specimens. The results showed that the pore volumes of concrete pores whose volumes were located at the interval [0.5 mm3, 20 mm3] have no big variation in both the amounts and volume of concrete pores, while others were found to have huge change during the process of experiment. The extent of damage acted by the repeated freezing and thawing gradually ranged from surface to complete disintegration of the interior of concrete specimens after 30 cycles of freeze-thaw acting.

  1. Fluctuations of a fluid inside a pore

    NARCIS (Netherlands)

    Zvelindovsky, AV; Zatovsky, AV

    The correlation theory of the thermal hydrodynamic fluctuations of compressible viscous fluids within a spherical pore has been developed. The fluctuation motions ape described by the linearized Navier-Stokes and heat transfer equations, containing spontaneous viscous stresses and heat fluxes. The

  2. Induction of nano pore in Agrobacterial hemoglobin

    Directory of Open Access Journals (Sweden)

    Mojtaba Tousheh

    2014-01-01

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

  3. Particle diffusion in complex nanoscale pore networks

    DEFF Research Database (Denmark)

    Müter, Dirk; Sørensen, Henning Osholm; Bock, H.;

    2015-01-01

    We studied the diffusion of particles in the highly irregular pore networks of chalk, a very fine-grained rock, by combining three-dimensional X-ray imaging and dissipative particle dynamics (DPD) simulations. X-ray imaging data were collected at 25 nm voxel dimension for two chalk samples with v...

  4. Maximal pore size in UF membranes

    NARCIS (Netherlands)

    Arkhangelsky, E.; Duek, A.; Gitis, V.

    2012-01-01

    The ultrafiltration membrane rejection capability is most often characterized by molecular weight cutoff (MWCO). The value is found by rejection of organic solutes and the evaluation of particle retention requires a conversion of either MWCO to pore size or particle diameter to molecular weight. The

  5. Silicon Pore Optics development for ATHENA

    DEFF Research Database (Denmark)

    Collon, Maximilien J.; Vacanti, Giuseppe; Guenther, Ramses

    2015-01-01

    ) to meet the science requirements of large effective area (1-2 m(2) at a few keV) at a focal length of 12 m. To meet the high angular resolution (5 arc seconds) requirement the X-ray lens will also need to be very accurate. Silicon Pore Optics (SPO) technology has been invented to enable building...

  6. Observations of sausage modes in magnetic pores

    CERN Document Server

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

    2010-01-01

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

  7. Fluctuations of a fluid inside a pore

    NARCIS (Netherlands)

    Zvelindovsky, AV; Zatovsky, AV

    1997-01-01

    The correlation theory of the thermal hydrodynamic fluctuations of compressible viscous fluids within a spherical pore has been developed. The fluctuation motions ape described by the linearized Navier-Stokes and heat transfer equations, containing spontaneous viscous stresses and heat fluxes. The e

  8. Fluctuations of a fluid inside a pore

    NARCIS (Netherlands)

    Zvelindovsky, AV; Zatovsky, AV

    1997-01-01

    The correlation theory of the thermal hydrodynamic fluctuations of compressible viscous fluids within a spherical pore has been developed. The fluctuation motions ape described by the linearized Navier-Stokes and heat transfer equations, containing spontaneous viscous stresses and heat fluxes. The e

  9. Pore-Forming Toxins Trigger the Purge.

    Science.gov (United States)

    Bonfini, Alessandro; Buchon, Nicolas

    2016-12-14

    The intestinal epithelium responds to pathogens by coordinating microbial elimination with tissue repair, both required to survive an infection. In this issue of Cell Host & Microbe, Lee et al. (2016) discover a rapid and evolutionarily conserved response to pore-forming toxins in the gut, involving cytoplasm ejection and enterocyte regrowth.

  10. Silicon Pore Optics development for ATHENA

    DEFF Research Database (Denmark)

    Collon, Maximilien J.; Vacanti, Giuseppe; Guenther, Ramses;

    2015-01-01

    ) to meet the science requirements of large effective area (1-2 m(2) at a few keV) at a focal length of 12 m. To meet the high angular resolution (5 arc seconds) requirement the X-ray lens will also need to be very accurate. Silicon Pore Optics (SPO) technology has been invented to enable building...

  11. Facial skin pores: a multiethnic study

    Science.gov (United States)

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

    2015-01-01

    Skin pores (SP), as they are called by laymen, are common and benign features mostly located on the face (nose, cheeks, etc) that generate many aesthetic concerns or complaints. Despite the prevalence of skin pores, related literature is scarce. With the aim of describing the prevalence of skin pores and anatomic features among ethnic groups, a dermatoscopic instrument, using polarized lighting, coupled to a digital camera recorded the major features of skin pores (size, density, coverage) on the cheeks of 2,585 women in different countries and continents. A detection threshold of 250 μm, correlated to clinical scorings by experts, was input into a specific software to further allow for automatic counting of the SP density (N/cm2) and determination of their respective sizes in mm2. Integrating both criteria also led to establishing the relative part of the skin surface (as a percentage) that is actually covered by SP on cheeks. The results showed that the values of respective sizes, densities, and skin coverage: 1) were recorded in all studied subjects; 2) varied greatly with ethnicity; 3) plateaued with age in most cases; and 4) globally refected self-assessment by subjects, in particular those who self-declare having “enlarged pores” like Brazilian women. Inversely, Chinese women were clearly distinct from other ethnicities in having very low density and sizes. Analyzing the present results suggests that facial skin pore’s morphology as perceived by human eye less result from functional criteria of associated appendages such as sebaceous glands. To what extent skin pores may be viewed as additional criteria of a photo-altered skin is an issue to be further addressed. PMID:25733918

  12. Impact of NAPL architecture on interphase mass transfer: A pore network study

    Science.gov (United States)

    Agaoglu, Berken; Scheytt, Traugott; Copty, Nadim K.

    2016-09-01

    Interphase mass transfer in porous media is commonly modeled using Sherwood number expressions that are developed in terms of fluid and porous medium properties averaged over some representative elementary volume (REV). In this work the influence of sub-grid scale properties on interphase mass transfer was investigated using a two-dimensional pore network model. The focus was on assessing the impact of (i) NAPL saturation, (ii) interfacial area (iii) NAPL spatial distribution at the pore scale, (iv) grain size heterogeneity, (v) REV or domain size and (vi) pore scale heterogeneity of the porous media on interphase mass transfer. Variability of both the mass transfer coefficient that explicitly accounts for the interfacial area and the mass transfer coefficient that lumps the interfacial area was examined. It was shown that pore scale NAPL distribution and its orientation relative to the flow direction have significant impact on flow bypassing and the interphase mass transfer coefficient. This results in a complex non-linear relationship between interfacial area and the REV-based interphase mass transfer rate. Hence, explicitly accounting for the interfacial area does not eliminate the uncertainty of the mass transfer coefficient. It was also shown that, even for explicitly defined flow patterns, changing the domain size over which the mass transfer process is defined influences the extent of NAPL bypassing and dilution and, consequently, the interphase mass transfer. It was also demonstrated that the spatial variability of pore scale parameters such as pore throat diameters may result in different rates of interphase mass transfer even for the same pore size distribution index.

  13. Quantitative analysis of nano-pore geomaterials and representative sampling for digital rock physics

    Science.gov (United States)

    Yoon, H.; Dewers, T. A.

    2014-12-01

    Geomaterials containing nano-pores (e.g., shales and carbonate rocks) have become increasingly important for emerging problems such as unconventional gas and oil resources, enhanced oil recovery, and geologic storage of CO2. Accurate prediction of coupled geophysical and chemical processes at the pore scale requires realistic representation of pore structure and topology. This is especially true for chalk materials, where pore networks are small and complex, and require characterization at sub-micron scale. In this work, we apply laser scanning confocal microscopy to characterize pore structures and microlithofacies at micron- and greater scales and dual focused ion beam-scanning electron microscopy (FIB-SEM) for 3D imaging of nanometer-to-micron scale microcracks and pore distributions. With imaging techniques advanced for nano-pore characterization, a problem of scale with FIB-SEM images is how to take nanometer scale information and apply it to the thin-section or larger scale. In this work, several texture characterization techniques including graph-based spectral segmentation, support vector machine, and principal component analysis are applied for segmentation clusters represented by 1-2 FIB-SEM samples per each cluster. Geometric and topological properties are analyzed and lattice-Boltzmann method (LBM) is used to obtain permeability at several different scales. Upscaling of permeability to the Darcy scale (e.g., the thin-section scale) with image dataset will be discussed with emphasis on understanding microfracture-matrix interaction, representative volume for FIB-SEM sampling, and multiphase flow and reactive transport. Funding from the DOE Basic Energy Sciences Geosciences Program is gratefully acknowledged. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under

  14. A fast Laplace solver approach to pore scale permeability

    Science.gov (United States)

    Arns, Christoph; Adler, Pierre

    2017-04-01

    The permeability of a porous medium can be derived by solving the Stokes equations in the pore space with no slip at the walls. The resulting velocity averaged over the pore volume yields the permeability KS by application of the Darcy law. The Stokes equations can be solved by a number of different techniques such as finite differences, finite volume, Lattice Boltzmann, but whatever the technique it remains a heavy task since there are four unknowns at each node (the three velocity components and the pressure) which necessitate the solution of four equations (the projection of Newton's law on each axis and mass conservation). By comparison, the Laplace equation is scalar with a single unknown at each node. The objective of this work is to replace the Stokes equations by an elliptical equation with a space dependent permeability. More precisely, the local permeability k is supposed to be proportional to (r-alpha)**2 where r is the distance of the voxel to the closest wall, and alpha a constant; k is zero in the solid phase. The elliptical equation is div(k gradp)=0. A macroscopic pressure gradient is assumed to be exerted on the medium and again the resulting velocity averaged over space yields a permeability K_L. In order to validate this method, systematic calculations have been performed. First, elementary shapes (plane channel, circular pipe, rectangular channels) were studied for which flow occurs along parallel lines in which case KL is the arithmetic average of the k's. KL was calculated for various discretizations of the pore space and various values of alpha. For alpha=0.5, the agreement with the exact analytical value of KS is excellent for the plane and rectangular channels while it is only approximate for circular pipes. Second, the permeability KL of channels with sinusoidal walls was calculated and compared with analytical results and numerical ones provided by a Lattice Boltzmann algorithm. Generally speaking, the discrepancy does not exceed 25% when

  15. Influence of pore structure on carbon retention/loss in soil macro-aggregates

    Science.gov (United States)

    Quigley, Michelle; Kravchenko, Alexandra; Rivers, Mark

    2017-04-01

    Carbon protection within soil macro-aggregates is an important component of soil carbon sequestration. Pores, as the transportation network for microorganisms, water, air and nutrients within macro-aggregates, are among the factors controlling carbon protection through restricting physical accessibility of carbon to microorganisms. The understanding of how the intra-aggregate pore structure relates to the degree of carbon physical protection, however, is currently lacking. This knowledge gap can lead to potentially inaccurate models and predictions of soil carbon's fate and storage in future changing climates. This study utilized the natural isotopic difference between C3 and C4 plants to trace the location of newly added carbon within macro-aggregates before and after decomposition and explored how location of this carbon relates to characteristics of intra-aggregate pores. To mimic the effect of decomposition, aggregates were incubated at 23˚ C for 28 days. Computed micro-tomographic images were used to determine pore characteristics at 6 μm resolution before and after incubation. Soil (0-10 cm depth) from a 20 year continuous corn (C4 plant) experiment was used. Two soil treatments were considered: 1) "destroyed-structure", where 1 mm sieved soil was used and 2) "intact-structure", where intact blocks of soil were used. Cereal rye (Secale cereale L.) (C3 plant) was grown in the planting boxes (2 intact, 3 destroyed, and one control) for three months in a greenhouse. From each box, ˜5 macro-aggregates of ˜5 mm size were collected for a total of 27 macro-aggregates. Half of the aggregates were cut into 5-11 sections, with relative positions of the sections within the aggregate recorded, and analyzed for δ13C. The remaining aggregates were incubated and then subjected to cutting and δ13C analysis. While there were no significant differences between the aggregate pore size distributions of the two treatments, the roles that specific pores sizes played in

  16. Experimental Investigation on Pore Structure Characterization of Concrete Exposed to Water and Chlorides

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2014-09-01

    Full Text Available In this paper, the pore structure characterization of concrete exposed to deionised water and 5% NaCl solution was evaluated using mercury intrusion porosity (MIP, scanning electron microscopy (SEM and X-ray diffraction (XRD. The effects of calcium leaching, fly ash incorporation, and chloride ions on the evolution of pore structure characteristics were investigated. The results demonstrate that: (i in ordinary concrete without any fly ash, the leaching effect of the cement products is more evident than the cement hydration effect. From the experimental data, Ca(OH2 is leached considerably with the increase in immersion time. The pore structure of concrete can also be affected by the formation of an oriented structure of water in concrete materials; (ii incorporation of fly ash makes a difference for the performance of concrete submersed in solutions as the total porosity and the pore connectivity can be lower. Especially when the dosage of fly ash is up to 30%, the pores with the diameter of larger than 100 nm show significant decrease. It demonstrates that the pore properties are improved by fly ash, which enhances the resistance against the calcium leaching; (iii chlorides have a significant impact on microstructure of concrete materials because of the chemical interactions between the chlorides and cement hydrates.

  17. Characterisation of matrix pore water at the Olkiluoto investigation site, Finland

    Energy Technology Data Exchange (ETDEWEB)

    Eichinger, F.L.

    2006-12-15

    Pore water that resides in the interconnected pore space between minerals and along grain boundaries in crystalline rocks of low permeability has been extracted successfully by tested laboratory out-diffusion methods using drillcore samples from borehole KR 39 located in the Olkiluoto subarea. The obtained experiment solutions have been characterised chemically and isotopically and related to the in situ pore water composition of the rock. In addition, the method of extraction, together with interfaced measurements of interconnected porosity, provided the opportunity to derive diffusion coefficient values of potential use in predicting future rates of solute transport. Because of the very small volumes of pore water extracted, and the possibility of rock stress release occurring during drilling which might: (a) lead to contamination by drilling fluid, (b) affect the derivation of rock porosity values, and (c) result in input of fluids from ruptured fluid inclusions, great care was taken to avoid such problems or, at least further understand the repercussions. Interpretations of the extracted pore waters are supported by investigations of the rock mineralogy, mineral chemistry, whole-rock chemistry, mineral fluid inclusions, and crush-leach experiments. (orig.)

  18. A Pore-Centric Model for Combined Shrinkage and Gas Porosity in Alloy Solidification

    Science.gov (United States)

    Khalajzadeh, Vahid; Carlson, Kent D.; Backman, Daniel G.; Beckermann, Christoph

    2017-04-01

    A unified model has been developed for combined gas- and shrinkage-induced pore formation during solidification of metal alloys. The model is based on a pore-centric approach, in which the temporal evolution of the pore radius is calculated as a function of cooling rate, thermal gradient, gas diffusion, and shrinkage. It accounts for the effect of porosity formation on the liquid velocity within the mushy zone. Simulations for an aluminum alloy show that the porosity transitions smoothly from shrinkage-induced to gas-induced as the Niyama value is increased. A Blake (cavitation) instability is observed to occur when the porosity is both gas- and shrinkage-driven. A revised dimensionless Niyama curve for pure shrinkage is presented. The experimentally observed gas porosity trend that the pore volume decreases with increasing cooling rate is well predicted. The pore-centric formulation allows the present model to be solved locally, at any point in a casting, during a regular casting simulation.

  19. Demixing and confinement of non-additive hard-sphere mixtures in slit pores.

    Science.gov (United States)

    Almarza, N G; Martín, C; Lomba, E; Bores, C

    2015-01-07

    Using Monte Carlo simulation, we study the influence of geometric confinement on demixing for a series of symmetric non-additive hard spheres mixtures confined in slit pores. We consider both a wide range of positive non-additivities and a series of pore widths, ranging from the pure two dimensional limit to a large pore width where results are close to the bulk three dimensional case. Critical parameters are extracted by means of finite size analysis. As a general trend, we find that for this particular case in which demixing is induced by volume effects, the critical demixing densities (and pressures) increase due to confinement between neutral walls, following the expected behavior for phase equilibria of systems confined by pure repulsive walls: i.e., confinement generally enhances miscibility. However, a non-monotonous dependence of the critical pressure and density with pore size is found for small non-additivities. In this latter case, it turns out that an otherwise stable bulk mixture can be unexpectedly forced to demix by simple geometric confinement when the pore width decreases down to approximately one and a half molecular diameters.

  20. Adaptive Multi-Scale Pore Network Method for Two-Phase Flow in Porous Media

    Science.gov (United States)

    Meyer, D. W.; Khayrat, K.; Jenny, P.

    2015-12-01

    Dynamic pore network simulators are important tools in studying macroscopic quantities in two-phase flow through porous media. However, these simulators have a time complexity of order N2 for N pore bodies, which limits their usage to small domains. Quasi-static pore network simulators, which assume capillary dominated flow, are more efficient with a time complexity of order N log(N), but are unable to capture phenomena caused by viscous effects such as viscous fingering and stable displacement. It has been experimentally observed that, in several flow scenarios, capillary forces are dominant at the pore scale and viscous forces at larger scales. In order to take advantage of this behaviour and to reduce the time complexity of existing dynamic pore network simulators, we propose a multi-scale pore-network method for two phase flow. In our solution algorithm, the pore network is first divided into smaller subnetworks. The algorithm to advance the fluid interfaces within each subnetwork consists of three steps: 1) The saturation rate of each subnetwork is obtained by solving a two-phase meso-scale mass balance equation over the domain of subnetworks. Here, a multi-point flux scheme is used. 2) Depending on the local capillary number computed in the subnetwork, either an invasion percolation algorithm or a dynamic network algorithm is used to locally advance the fluid-fluid interfaces within each subnetwork until a new saturation value is matched. 3) The transmissibilities for the meso-scale equation are updated based on the updated fluid configurations in each subnetwork. For this purpose the methodoloy of the existing multi-scale finite volume (MSFV) method is employed. An important feature of the multi-scale pore-network method is that it maintains consistency of both fluid occupancy and fluxes at subnetwork interfaces. Viscous effects such as viscous fingering (see figure) can be captured at a decreased computational cost compared to dynamic pore network

  1. Troglitazone treatment increases bone marrow adipose tissue volume but does not affect trabecular bone volume in mice

    DEFF Research Database (Denmark)

    Erikstrup, Lise Tornvig; Mosekilde, Leif; Justesen, J;

    2001-01-01

    proliferator activated receptor-gamma (PPARgamma). Histomorphometric analysis of proximal tibia was performed in order to quantitate the amount of trabecular bone volume per total volume (BV/TV %), adipose tissue volume per total volume (AV/TV %), and hematopoietic marrow volume per total volume (HV...

  2. Development and deployment of a deep-sea Raman probe for measurement of pore water geochemistry

    Science.gov (United States)

    Zhang, Xin; Walz, Peter M.; Kirkwood, William J.; Hester, Keith C.; Ussler, William; Peltzer, Edward T.; Brewer, Peter G.

    2010-02-01

    We have developed, deployed, and tested a novel probe for study of the geochemistry of sediment pore waters based upon Raman spectroscopy. The Raman technique has already been used successfully for in situ measurements of targets of scientific interest including gas and hydrothermal vents and complex gas hydrates, but sediment geochemistry has so far been an intractable problem since the sediments themselves are strongly fluorescent and typically only very small sample volumes are obtainable. The 35 cm long probe extracts pore fluids through a 10 μm sintered metallic frit and draws the sample through a 2 mm diameter channel into a sapphire windowed optical cell within which the laser beam is focused and the spectrum recorded. The dead volume of the system is ˜1 ml and the instrument is ROV deployable with activation of probe insertion and sample withdrawal under direct operator control. The unique features of this mode of detection include observation of the sulfate gradient in marine pore waters as an indicator of diagenesis, direct measurement of the dissolved sulfide species H 2S and HS -, and measurement of dissolved methane; all of which are of primary geochemical interest. Quantitative analysis is achieved by area ratio to known water peaks and from standard calibration curves with a precision of ±5%. We find only very small fluorescence from pore waters measured in situ, but observe rapid increases in fluorescence from cores returned to the surface and exposed to oxygen.

  3. Pore structure development of in-situ pyrolyzed coals for pollution prevention in iron foundries

    Energy Technology Data Exchange (ETDEWEB)

    Huang, He; Cannon, Fred S. [Department of Civil and Environmental Engineering, The Pennsylvania State University, 212 Sackett Building, University Park, PA 16802 (United States); Wang, Yujue [Department of Environmental Science and Engineering, Tsinghua University, Bejing, 100084 (China)

    2009-09-15

    A protocol was devised for preparing pyrolyzed coals that could be made in-situ at foundries to capture volatile organic compound (VOC) emission. This pyrolysis created extensive micropore volume in lignite over a broad range of temperature and time; and could use waste heat from cupola exhaust gases by a heat-exchange tube. For foundry application, moderate porous carbon with relatively uniform pores over wide ranges of temperature and time would be more practical than highly porous activated carbon (AC) that requires narrowly-controlled operations. This pyrolysis protocol was developed in a thermogravimetric analyzer (TGA) and in a small tube furnace, while using lignite, bituminous coal, and anthracite. The lignite yielded the most pore volume; and this was relatively uniform (0.1-0.13 mL/g of pores) while temperatures were 600-900 C, and times were 0-60 min. Smaller grain sizes yielded improved porosity; and this corresponded to more release of phenols and naphthalenes from smaller grains, as discerned by TGA-mass spectroscopy (MS). TGA-MS also revealed that improved pore development between 600-800 C corresponded to the release of CO{sub 2} and H{sub 2}O; and concurrently higher slurry pH linked to less oxygenated functionality. Adsorption of benzene was compared between the in-situ porous carbon and a commercial AC. (author)

  4. Laser scanning confocal microscopy characterization of water repellent distribution in a sandstone pore network.

    Science.gov (United States)

    Zoghlami, Karima; Gómez-Gras, David; Corbella, Mercè; Darragi, Fadila

    2008-11-01

    In the present work, we propose the use of the Laser Scanning Confocal Microscopy (LSCM) to determine the effect of water repellents on rock's pore-network configuration and interconnection. The rocks studied are sandstones of Miocene age, a building material that is commonly found in the architectural heritage of Tunisia. The porosity quantitative data of treated and untreated samples, obtained by mercury porosimetry tests, were compared. The results show a slight decrease in total porosity with the water repellent treatment, which reduced both microporosity and macroporosity. This reduction produced a modification in pore size distribution and a shift of the pore access size mode interval toward smaller pore diameters (from the 30-40 microm to the 20-30 microm intervals). The water repellent was observed in SEM images as a continuous film coating grain surfaces; moreover, it was easily visualized in LSCM, by staining the water repellent with Epodye fluorochrome, and the coating thickness was straightforwardly measured (1.5-2 microm). In fact, the combination of mercury intrusion porosimetry data and LSCM observations suggests that the porosity reduction and the shift of the pore diameter mode were mainly due to the general reduction of pore diameters, but also to the plugging of the smallest pores (less than 3-4 microm in diameter) by the water repellent film. Finally, the LSCM technique enabled the reconstruction of 3D views of the water repellent coating film in the pore network, indicating that its distribution was uniform and continuous over the 100 microm thick sample. The LSCM imaging facilitates the integration and interpretation of mercury porosimetry and SEM data.

  5. Study of pores produced in underwater wet welding

    Institute of Scientific and Technical Information of China (English)

    Shen Xiaoqin; Liu Shiming

    2006-01-01

    This paper deals with the effect of water depth in the range of 10 m to 80 m upon the formation of pores produced during underwater wet welding. The results show that it is easy for the inner pores to occur owing to the particularity of the molten metal solidification that the outer pores begin to appear when the water depth increases to about 60 m, that the porosity increases and pore grows up as the water depth increases, and that pores are all hydrogen-cont aining ones through the examination of the variation of number of pores with the residual hydrogen and oxygen content in the weld metal.

  6. Lower Monoamine Oxidase-A Total Distribution Volume in Impulsive and Violent Male Offenders with Antisocial Personality Disorder and High Psychopathic Traits: An [(11)C] Harmine Positron Emission Tomography Study.

    Science.gov (United States)

    Kolla, Nathan J; Matthews, Brittany; Wilson, Alan A; Houle, Sylvain; Bagby, R Michael; Links, Paul; Simpson, Alexander I; Hussain, Amina; Meyer, Jeffrey H

    2015-10-01

    Antisocial personality disorder (ASPD) often presents with highly impulsive, violent behavior, and pathological changes in the orbitofrontal cortex (OFC) and ventral striatum (VS) are implicated. Several compelling reasons support a relationship between low monoamine oxidase-A (MAO-A), an enzyme that regulates neurotransmitters, and ASPD. These include MAO-A knockout models in rodents evidencing impulsive aggression and positron emission tomography (PET) studies of healthy subjects reporting associations between low brain MAO-A levels and greater impulsivity or aggression. However, a fundamental gap in the literature is that it is unknown whether brain MAO-A levels are low in more severe, clinical disorders of impulsivity, such as ASPD. To address this issue, we applied [(11)C] harmine PET to measure MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in 18 male ASPD participants and 18 age- and sex-matched controls. OFC and VS MAO-A VT were lower in ASPD compared with controls (multivariate analysis of variance (MANOVA): F2,33=6.8, P=0.003; OFC and VS MAO-A VT each lower by 19%). Similar effects were observed in other brain regions: prefrontal cortex, anterior cingulate cortex, dorsal putamen, thalamus, hippocampus, and midbrain (MANOVA: F7,28=2.7, P=0.029). In ASPD, VS MAO-A VT was consistently negatively correlated with self-report and behavioral measures of impulsivity (r=-0.50 to -0.52, all P-values<0.05). This study is the first to demonstrate lower brain MAO-A levels in ASPD. Our results support an important extension of preclinical models of impulsive aggression into a human disorder marked by pathological aggression and impulsivity.

  7. Lower Monoamine Oxidase-A Total Distribution Volume in Impulsive and Violent Male Offenders with Antisocial Personality Disorder and High Psychopathic Traits: An [11C] Harmine Positron Emission Tomography Study

    Science.gov (United States)

    Kolla, Nathan J; Matthews, Brittany; Wilson, Alan A; Houle, Sylvain; Michael Bagby, R; Links, Paul; Simpson, Alexander I; Hussain, Amina; Meyer, Jeffrey H

    2015-01-01

    Antisocial personality disorder (ASPD) often presents with highly impulsive, violent behavior, and pathological changes in the orbitofrontal cortex (OFC) and ventral striatum (VS) are implicated. Several compelling reasons support a relationship between low monoamine oxidase-A (MAO-A), an enzyme that regulates neurotransmitters, and ASPD. These include MAO-A knockout models in rodents evidencing impulsive aggression and positron emission tomography (PET) studies of healthy subjects reporting associations between low brain MAO-A levels and greater impulsivity or aggression. However, a fundamental gap in the literature is that it is unknown whether brain MAO-A levels are low in more severe, clinical disorders of impulsivity, such as ASPD. To address this issue, we applied [11C] harmine PET to measure MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in 18 male ASPD participants and 18 age- and sex-matched controls. OFC and VS MAO-A VT were lower in ASPD compared with controls (multivariate analysis of variance (MANOVA): F2,33=6.8, P=0.003; OFC and VS MAO-A VT each lower by 19%). Similar effects were observed in other brain regions: prefrontal cortex, anterior cingulate cortex, dorsal putamen, thalamus, hippocampus, and midbrain (MANOVA: F7,28=2.7, P=0.029). In ASPD, VS MAO-A VT was consistently negatively correlated with self-report and behavioral measures of impulsivity (r=−0.50 to −0.52, all P-values<0.05). This study is the first to demonstrate lower brain MAO-A levels in ASPD. Our results support an important extension of preclinical models of impulsive aggression into a human disorder marked by pathological aggression and impulsivity. PMID:26081301

  8. Prognostic value of whole-body metabolic tumour volume and total lesion glycolysis measured on {sup 18}F-FDG PET/CT in patients with extranodal NK/T-cell lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Choon-Young; Hong, Chae Moon; Kim, Do-Hoon; Son, Seung Hyun; Jeong, Shin Young; Lee, Sang-Woo; Lee, Jaetae; Ahn, Byeong-Cheol [Kyungpook National University School of Medicine and Hospital, Department of Nuclear Medicine, Daegu (Korea, Republic of)

    2013-09-15

    The aim of this study was to determine whether maximum standardized uptake value (SUVmax), whole-body metabolic tumour volume (WBMTV), and whole-body total lesion glycolysis (WBTLG) measured on pretreatment {sup 18}F-FDG PET/CT can predict prognosis in patients with extranodal natural killer/T-cell lymphoma (ENKTL). We conducted a retrospective analysis of 20 patients with newly-diagnosed ENKTL who underwent pretreatment {sup 18}F-FDG PET/CT. WBMTV and WBTLG were measured automatically using the boundaries of voxels presenting SUV > 3.0. Uni- and multivariate analyses for survival and disease progression were performed using clinical variables and PET parameters (SUVmax, WBMTV, and WBTLG). During the follow-up period (median 26.3 months), 12 patients showed disease progression and 10 patients died from the disease. Receiver operating characteristic curve analysis showed cut-off values for SUVmax, WBMTV and WBTLG of 8.1, 14.4 cm{sup 3} and 52.7, respectively. Univariate analysis showed that the International Prognostic Index (IPI) score and PET parameters were significant predictors of overall survival (OS) and progression-free survival (PFS). Multivariate analysis, even after adjustment for the IPI score, showed that high WBMTV was the best predictor of OS and PFS, and high SUVmax and WBTLG were significant predictors of PFS. Our results suggested that the use of PET parameters together with the IPI score may be useful for detailed prediction of prognosis in ENKTL patients. Therefore, despite a lower IPI score, patients with high PET parameter values might be considered candidates for aggressive therapy to improve clinical outcomes. (orig.)

  9. 钙质砂颗粒内孔隙的结构特征分析%Microscopic characterization of intra-pore structures of calcareous sands

    Institute of Scientific and Technical Information of China (English)

    朱长歧; 陈海洋; 孟庆山; 汪稔

    2014-01-01

    钙质砂是一种碳酸钙含量达50%以上的海洋生物成因的颗粒状材料。从微观结构上来看,钙质砂颗粒棱角度高、形状不规则、强度低、易破碎,且颗粒含有内孔隙。内孔隙的存在深刻影响着钙质砂的压缩、剪切和破碎等力学性能。利用激光技术对南沙群岛永暑礁环礁泻湖的未胶结钙质砂颗粒进行飞秒切割,通过光学显微镜探查并获取了颗粒的内孔隙图像,借助MATLAB图像处理软件,对钙质砂颗粒的内孔隙进行了定量分析。结果表明:较大颗粒钙质砂的内孔隙断面孔隙度相对较大,小孔隙数量较多,而大孔隙所占空间则较大;对于1 mm以上的钙质砂,缝隙状内孔隙含量远低于等轴或不等轴孔隙,等轴与不等轴内孔数量大致相等。%Calcareous sands are consisted of marine biogenic granular materials with carbonate content often greater than 50%. From the microscopic viewpoint, calcareous sand grains demonstrate highly angular and irregular in shapes and contain intra-pores. This unique intra-pore structure of calcareous sand particle is prone to crush under stress. Therefore, the calcareous sand has a relatively low strength. The intra-pore structure has a significant effect on the geotechnical properties of calcareous sands. Calcareous sand samples from the lagoon of Yongshu Reef atoll, Nansha Islands, were cut by femtosecond laser for the optical microscopic studies. The intra-pore structures were quantitatively analyzed throughout the MATLAB digital image process tool. The results indicate that, larger porosity can be found on the breakage section of larger size calcareous sand and a larger number of small pores with small total volume are in the intra-pore structure. For sand grains with a size greater than one millimeter, the number of slit shape intra-pores is far less than the number of intra-voids with equiaxed or unequal axed pores. The amount of the equiaxed and

  10. Incorporation of the Pore Size Variation to Modeling of the Elastic Behavior of Metallic Open-Cell Foams

    Directory of Open Access Journals (Sweden)

    Ćwieka K.

    2017-03-01

    Full Text Available In the present paper we present the approach for modeling of the elastic behavior of open-cell metallic foams concerning non-uniform pore size distribution. This approach combines design of foam structures and numerical simulations of compression tests using finite element method (FEM. In the design stage, Laguerre-Voronoi tessellations (LVT were performed on several sets of packed spheres with defined variation of radii, bringing about a set of foam structures with porosity ranging from 74 to 98% and different pore size variation quantified by the coefficient of pore volume variation, CV(V, from 0.5 to 2.1. Each structure was numerically subjected to uni-axial compression test along three directions within the elastic region. Basing on the numerical response, the effective Young’s modulus, Eeff, was calculated for each structure. It is shown that the Eeff is not only dependent on the porosity but also on the pore size variation.

  11. Mesoporous ethanesilica materials with bimodal and trimodal pore-size distributions synthesised in the presence of cobalt ions

    Directory of Open Access Journals (Sweden)

    Alufelwi M. Tshavhungwe

    2010-07-01

    Full Text Available Mesoporous organosilica materials containing ethane groups in their framework were formed with two and three pore sizes (i.e. bimodal and trimodal pores when synthesised by the sol-gel method in the presence of cobalt ions. The compounds 1,2-bistrimethoxysilylethane and tetraethylorthosilicate were used as silicon sources and the reactions were done in the presence of a surfactant, which served as a template. Diffuse reflectance infrared Fourier transform spectroscopy revealed that organic functional groups were incorporated into the ethanesilica. Powder X-ray diffraction and nitrogen adsorption data indicated that the mesophase and textural properties (surface area, pore volume, pore diameter of the materials were dependent on the ageing temperature, the amount/ratio of silica precursors and cobalt ion incorporation. Secondary mesopores were drastically reduced by changing the ratio of silicon precursors.

  12. Numerical simulation of pore-scale flow in chemical flooding process

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Chemical flooding is one of the effective technologies to increase oil recovery of petroleum reservoirs after water flooding.Above the scale of representative elementary volume(REV), phenomenological modeling and numerical simulations of chemical flooding have been reported in literatures,but the studies alike are rarely conducted at the pore-scale,at which the effects of physicochemical hydrodynamics are hardly resolved either by experimental observations or by traditional continuum-based simulations.In...

  13. Mineral dissolution kinetics at the pore scale

    Energy Technology Data Exchange (ETDEWEB)

    Li, L.; Steefel, C.I.; Yang, L.

    2007-05-24

    Mineral dissolution rates in the field have been reported to be orders of magnitude slower than those measured in the laboratory, an unresolved discrepancy that severely limits our ability to develop scientifically defensible predictive or even interpretive models for many geochemical processes in the earth and environmental sciences. One suggestion links this discrepancy to the role of physical and chemical heterogeneities typically found in subsurface soils and aquifers in producing scale-dependent rates where concentration gradients develop. In this paper, we examine the possibility that scale-dependent mineral dissolution rates can develop even at the single pore and fracture scale, the smallest and most fundamental building block of porous media. To do so, we develop two models to analyze mineral dissolution kinetics at the single pore scale: (1) a Poiseuille Flow model that applies laboratory-measured dissolution kinetics at the pore or fracture wall and couples this to a rigorous treatment of both advective and diffusive transport, and (2) a Well-Mixed Reactor model that assumes complete mixing within the pore, while maintaining the same reactive surface area, average flow rate, and geometry as the Poiseuille Flow model. For a fracture, a 1D Plug Flow Reactor model is considered in addition to quantify the effects of longitudinal versus transverse mixing. The comparison of averaged dissolution rates under various conditions of flow, pore size, and fracture length from the three models is used as a means to quantify the extent to which concentration gradients at the single pore and fracture scale can develop and render rates scale-dependent. Three important minerals that dissolve at widely different rates, calcite, plagioclase, and iron hydroxide, are considered. The modeling indicates that rate discrepancies arise primarily where concentration gradients develop due to comparable rates of reaction and advective transport, and incomplete mixing via molecular

  14. Evolution of Pore Size Distribution and Mean Pore Size in Lotus-type Porous Magnesium Fabricated with Gasar Process

    Institute of Scientific and Technical Information of China (English)

    Yuan LIU; Yanxiang LI; Huawei ZHANG; Jiang WAN

    2006-01-01

    The effect of gas pressures on the mean pore size, the porosity and the pore size distribution of lotus-type porous magnesium fabricated with Gasar process were investigated. The theoretical analysis and the experimental results all indicate that there exists an optimal ratio of the partial pressures of hydrogen pH2 to argon pAr for producing lotus-type structures with narrower pore size distribution and smaller pore size. The effect of solidification mode on the pore size distribution and pore size was also discussed.

  15. Induction of nano pore in Agrobacterial hemoglobin

    OpenAIRE

    Mojtaba Tousheh; Giti Emtiazi; Peyman Derikvand

    2014-01-01

    Introduction: A variety of oxygen-transport and -binding proteins exist in organisms including bacteria, protozoans, and fungi all have hemoglobin-like proteins. In addition to dealing with transport and sensing of oxygen, they may also deal with NO2, CO2, sulfide compounds, and even O2 scavenging in environments. Also they detoxified chlorinated materials like P450 enzymes and peroxidases and use as a detector of nitrate and hydrogen peroxide. Pore-forming bacterial globins are interested fo...

  16. Pore Scale Heterogeneity in the Mineral Distribution and Surface Area of Porous Rocks

    Science.gov (United States)

    Lai, Peter; Krevor, Sam

    2015-04-01

    An important control on rate of interfacial processes between minerals and aqueous solutions such as nucleation of solids, and mineral dissolution and growth is reactive surface area. In geochemical modelling, the continuum hypothesis is based on the assumption that the system can be represented by a sufficiently large number of representative elemental volumes. There has been recent interest in studying the impact of this assumption on reaction-transport coupled systems. In this study, the impact of pore-scale heterogeneity on the distribution of reactive surface area is discussed. 3D images obtained using x-ray micro-tomography were used to characterise the distribution of reactive surface area. The results were compared to independent observations. Mineral identification using x- ray diffraction and fluorescence suggested general agreement with CT analysis. Nitrogen BET surface areas were one to two orders of magnitude higher than measurements from x-ray imagery. Co- registered images of Berea sandstone from x-ray and energy dispersive spectroscopy imagery suggested that quartz, K-feldspar and most clays could be identified. However, minor minerals such as albite and illite did not exhibit enough contrast. In Berea sandstone, mineral surface area fraction was poorly correlated to the mineral volumetric fraction. Clay and feldspar minerals exhibited higher surface area fractions than bulk mineralogy suggested. In contrast, in the Edwards carbonate samples, modal mineral composition correlated with mineral-specific surface area. Berea sandstone revealed a characteristic pore size at which a surface area distribution may be used to quantify heterogeneity. Conversely, the carbonate samples suggested a continuous range of pore sizes across length scales. A comparison with pore network model simulations from the literature was made. First order estimates of mineral specific correlations between geometric area measured in the x-ray images were used to convert the CT

  17. Biomimetic collagen scaffolds with anisotropic pore architecture.

    Science.gov (United States)

    Davidenko, N; Gibb, T; Schuster, C; Best, S M; Campbell, J J; Watson, C J; Cameron, R E

    2012-02-01

    Sponge-like matrices with a specific three-dimensional structural design resembling the actual extracellular matrix of a particular tissue show significant potential for the regeneration and repair of a broad range of damaged anisotropic tissues. The manipulation of the structure of collagen scaffolds using a freeze-drying technique was explored in this work as an intrinsically biocompatible way of tailoring the inner architecture of the scaffold. The research focused on the influence of temperature gradients, imposed during the phase of crystallisation of collagen suspensions, upon the degree of anisotropy in the microstructures of the scaffolds produced. Moulding technology was employed to achieve differences in heat transfer rates during the freezing processes. For this purpose various moulds with different configurations were developed with a view to producing uniaxial and multi-directional temperature gradients across the sample during this process. Scanning electron microscopy analysis of different cross-sections (longitudinal and horizontal) of scaffolds revealed that highly aligned matrices with axially directed pore architectures were obtained where single unidirectional temperature gradients were induced. Altering the freezing conditions by the introduction of multiple temperature gradients allowed collagen scaffolds to be produced with complex pore orientations, and anisotropy in pore size and alignment.

  18. Pore morphology study of silica aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Hua, D.W.; Anderson, J.; Haereid, S.; Smith, D.M. [UNM/NSF Center for Micro-Engineered Ceramics, Albuquerque, NM (United States); Beaucage, G. [Sandia National Labs., Albuquerque, NM (United States)

    1994-12-31

    Silica aerogels have numerous properties which suggest applications such as ultra high efficiency thermal insulation. These properties relate directly to the aerogel`s pore size distribution. The micro and meso pore size ranges can be investigated by normal small angle x-ray scattering and possibly, nitrogen adsorption. However, the measurement of larger pores (> 250 {angstrom}) is more difficult. Due to their limited mechanical strength, mercury porosimetry and nitrogen condensation can disrupt the gel structure and electron microscopy provides only limited large scale structure information. The use of small angle light scattering techniques seems to have promise, the only hurdle is that aerogels exhibit significant multiple scattering. This can be avoided if one observes the gels in the wet stage since the structure of the aerogel should be very similar to the wet gel (as the result of supercritical drying). Thus, if one can match the refractive index, the morphology can be probed. The combination of certain alcoholic solvents fit this index matching criteria. Preliminary results for the gel network (micron range) and primary particle structure (manometer) are reported by using small angle light scattering and ultra-small angle x-ray scattering. The effects on structure over the length scale range of <1 nm to >5 {mu}m under different conditions (precursors, pH, etc.) are presented. The change in structure of an aerogel during isostatic compaction to 228 MPa (to simulate drying from wetting solvents) are also discussed.

  19. Mercury in contaminated sediments and pore waters enriched in sulphate (Tagus Estuary, Portugal)

    Energy Technology Data Exchange (ETDEWEB)

    Canario, J.; Vale, C.; Caetano, M.; Madureira, M.J

    2003-12-01

    Three sediment cores, collected nearby the effluent of a chlor-alkali industry, were sliced in 0.5-cm layers and centrifuged for pore water extraction. Mercury, Fe and Mn were determined in the solids as total concentration, hydroxylamine extractable fraction and HCl extractable fraction. Sulphur was determined in the HCl extraction. Total and reactive mercury, chlorinity, S{sup 2-}, SO{sub 4}{sup 2-}, total Fe, and total Mn were measured in pore waters. The solids contained 3.0-60 nmol g{sup -1} of total Hg and pore waters 70-5800 pM of total Hg and 1.8-76 pM of reactive mercury. Pore waters presented 2.3-94 times more sulphate than the overlying estuarine waters due to the input from the industry. In layers where hydroxylamine extractable Fe exhibited a broad maximum (precipitation of Fe-oxides) sulphate was reduced to S{sup 2-}. The competition between the high content of SO{sub 4}{sup 2-} and Fe(III) as electron acceptors, in chemical reactions occurring in the upper sediments, may explain the co-existence of S{sup 2-} and Fe-oxides in the same layers. Mercury was detected in the hydroxylamine extracts (20-29 nmolg{sup -1}) in the layers where Fe-oxides were formed, and reactive dissolved Hg showed minimum concentrations. The excess of sulphate in pore waters favoured the abundant Fe-oxides in the upper solid sediments, which appear to work as a barrier limiting the escape of mercury to the water column. - Excess sulfate in sore water favours the binding of mercury into iron oxides, limiting escape into the overlying water.

  20. Mercury in contaminated sediments and pore waters enriched in sulphate (Tagus Estuary, Portugal).

    Science.gov (United States)

    Canário, J; Vale, C; Caetano, M; Madureira, M J

    2003-01-01

    Three sediment cores, collected nearby the effluent of a chlor-alkali industry, were sliced in 0.5-cm layers and centrifuged for pore water extraction. Mercury, Fe and Mn were determined in the solids as total concentration, hydroxylamine extractable fraction and HCl extractable fraction. Sulphur was determined in the HCl extraction. Total and reactive mercury, chlorinity, S(2-), SO(4)(2-), total Fe, and total Mn were measured in pore waters. The solids contained 3.0-60 nmol g(-1) of total Hg and pore waters 70-5800 pM of total Hg and 1.8-76 pM of reactive mercury. Pore waters presented 2.3-94 times more sulphate than the overlying estuarine waters due to the input from the industry. In layers where hydroxylamine extractable Fe exhibited a broad maximum (precipitation of Fe-oxides) sulphate was reduced to S(2-). The competition between the high content of SO(4)(2-) and Fe(III) as electron acceptors, in chemical reactions occurring in the upper sediments, may explain the co-existence of S(2-) and Fe-oxides in the same layers. Mercury was detected in the hydroxylamine extracts (20-29 nmolg(-1)) in the layers where Fe-oxides were formed, and reactive dissolved Hg showed minimum concentrations. The excess of sulphate in pore waters favoured the abundant Fe-oxides in the upper solid sediments, which appear to work as a barrier limiting the escape of mercury to the water column.

  1. INVESTIGATIONS INTO BIOFOULING PHENOMENA IN FINE PORE AERATION DEVICES

    Science.gov (United States)

    Microbiologically-based procedures were used to describe biofouling phenomena on fine pore aeration devices and to determine whether biofilm characteristics could be related to diffuser process performance parameters. Fine pore diffusers were obtained from five municipal wastewa...

  2. Bulk Volume Reduction of the Kimmeridge Clay Formation, North Sea (UK Due to Compaction, Petroleum Generation and Expulsion

    Directory of Open Access Journals (Sweden)

    Kenneth S. Okiongbo

    2011-02-01

    Full Text Available In this study, the effects of petroleum generation and expulsion on shale porosity is explored by evaluating the compaction of the Kimmeridge Clay Formation (KCF within the oil window using log data and shale samples from the KCF within the depth and temperature range of ~1.5-5.0 km and 90-157ºC, respectively. Petrophysical properties e.g porosity and pore-size distribution were measured, and permeability was calculated using empirical models based on the measured porosities. Transit-time values from the sonic logs recorded at depths in the wells were the cores were recovered were calibrated against the porosities determined from the core samples. Bulk geochemical parameters e.g., Total Organic Carbon (TOC, Hydrogen Index (HI were determined. The volume reduction in the KCF within the oil window due to petroleum generation and expulsion, and compaction due to loss of pore space was determined using the geochemical and log derived porosity data emplaced into empirical relations. Porosities above the oil window range from ~15-20%, but decreased to <5% at the end of the oil window. Pore-sizes decrease from ~11 nm to between 6-8 nm at the depth range of 1.5-5.0 km. Permeability decreased from 4.8 nD to ~0.095 nD. The quantitative estimations of volume reduction within the oil window indicate that for ~8.0wt% initial TOC sediment, a bulk volume reduction of 13% of the initial volume is due to oil expulsion, and ~12% is due to loss of pore space.

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

    Science.gov (United States)

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

    2016-09-01

    avoids the problem of partial volume effects and reduces the scaling effect by preserving the pore-space properties influencing the transport properties. This is evidently compared in this study by predicting several pore network properties such as number of pores and throats, average pore and throat radius and coordination number for both scan based analysis and numerical coarsened data.

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

    Science.gov (United States)

    Yang, Z.; Juanes, R.

    2015-12-01

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

  5. New ultrasonic technique for the study of the pore shape of track-etched pores in polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Alvarez-Arenas, T.E., E-mail: tgomez@ia.cetef.csic.e [Instituto de Acustica, CSIC, Serrano 144, 28006 Madrid (Spain); Apel, P.Yu.; Orelovitch, O.L. [Flerov Lab. of Nuclear Reactions, JINR, Dubna (Russian Federation); Munoz, M. [Institute of Applied Physics, CSIC, Serrano 144, Madrid (Spain)

    2009-10-15

    A new technique for the study of the pore shape of track-etched pores in polymer films is presented. This technique is based on the use of air-coupled ultrasounds and phase and magnitude spectral analysis. Transmission of ultrasounds through these membranes is made up of two contributions: propagation through the solid part and propagation along the pore channels. A time-domain procedure to separate these to contributions is presented. Sensitivity of ultrasounds propagation in the pore channels to variations of pore shape is studied. Membranes with similar properties (gas flow rate values) but slight differences in the pore shape are studied. The proposed technique reveals to be sensitive to such differences; unlike other techniques, it is capable to provide information in a separate way about pore aperture at the surface and pore diameter inside the membrane, in addition the technique is non-destructive.

  6. Prognostic significance of preoperative metabolic tumour volume and total lesion glycolysis measured by {sup 18}F-FDG PET/CT in squamous cell carcinoma of the oral cavity

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, In Sun; Roh, Jong-Lyel; Choi, Seung-Ho; Nam, Soon Yuhl [University of Ulsan College of Medicine, Department of Otolaryngology, Asan Medical Center, Seoul (Korea, Republic of); Kim, Jae Seung [University of Ulsan College of Medicine, Department of Nuclear Medicine, Asan Medical Center, Seoul (Korea, Republic of); Cho, Kyung-Ja [University of Ulsan College of Medicine, Department of Pathology, Asan Medical Center, Seoul (Korea, Republic of); Kim, Sang Yoon [University of Ulsan College of Medicine, Department of Otolaryngology, Asan Medical Center, Seoul (Korea, Republic of); Biomedical Research Institute, Korean Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-03-15

    Metabolic tumour volume (MTV) and total lesion glycolysis (TLG) from {sup 18}F-FDG PET/CT are emerging prognostic biomarkers in human solid cancers; yet few studies have investigated their clinical and prognostic significance in oral cavity squamous cell carcinoma (OSCC). The present retrospective study evaluated the utility of pretreatment MTV and TLG measured by {sup 18}F-FDG PET/CT to predict survival and occult metastasis (OM) in OSCC. Of 162 patients with OSCC evaluated preoperatively by {sup 18}F-FDG PET/CT, 105 who underwent definitive surgery with or without adjuvant therapy were eligible. Maximum standardized uptake value (SUV{sub max}), MTV and TLG were measured. For calculation of MTV, 3-D regions of interest were drawn and a SUV threshold of 2.5 was used for defining regions. Univariate and multivariate analyses identified clinicopathological and imaging variables associated with OM, disease-free survival (DFS) and overall survival (OS). The median (range) SUV{sub max}, MTV and TLG were 7.3 (0.7-41.9), 4.5 ml (0.7-115.1 ml) and 18.3 g (2.4-224.1 g), respectively. Of 53 patients with clinically negative lymph nodes, OM was detected in 19 (36 %). By univariate and multivariate analyses, MTV (P = 0.018) and TLG (P = 0.011) were both independent predictive factors for OM, although they were not independent of each other. The 4-year DFS and OS rates were 53.0 % and 62.0 %, respectively. Univariate and multivariate analyses revealed that MTV (P = 0.001) and TLG (P = 0.006), with different cut-off levels, were both independent predictive factors for DFS, although they were not independent of each other, and MTV (P = 0.001), TLG (P = 0.002) and the involved resection margin (P = 0.007) were independent predictive factors for OS. Pretreatment MTV and TLG may be useful in stratifying the likelihood of survival and predicting OM in OSCC. (orig.)

  7. Comparison of Pore Water Chemical Extracted by Different Forces with In-situ Properties

    Science.gov (United States)

    Ito, N.; Machida, I.; Marui, A.; Scheytt, T.; Hebig, K. H.

    2010-12-01

    Due to the difficulty involved for in-situ sampling of groundwater, pore water was extracted from rock core samples for chemical analysis. Available literature indicated that, the chemical constituents of pore water are affected by large extraction force. This study is therefore aimed at discussing the reason behind the change in pore water chemistry when samples are subjected to different extraction forces. The process involved extraction of pore water from sandstone core samples at different pF values by centrifuge method. The pF expresses the tension of water, retained in soil. It is the base 10 logarithm of tension, which is measured as a head of water head in centimeters. The samples of lengths 100 m each were obtained from three locations. Tracer test using Iodine was also conducted to remove pore water polluted by drilling water. Pore water was extracted from a total of 63 samples at three different values of pF (low: up to pF 2.3, medium: pF 2.3 - 3.9, high: pF 3.9 - 4.3). For each pF range the pore water was analyzed for major anions and cations. Results showed variation of ionic concentrations with pF and depth. The average concentrations rose with increase of pF in all ions except for potassium. Based on the concentration distribution of Ca2+, three zones could be defined: (1) Ca2+ concentration, which does not depend on pF, (2) Ca2+ concentration, which increases with the value of pF and (3) Ca2+ showing the same value for medium and high pF values. It is thus concluded that, water chemistry of deep pore water is likely to have reached equilibrium due to almost stagnant flow conditions, whereas shallow water is likely to participate in chemical interactions due to the relatively high flow velocity. The depths of the interfaces of these three zones are almost consistent with geological boundaries of weathered and fine sandstone and there is evidence of a relationship between pore water chemistry and physical rock properties. Using this knowledge, we

  8. Influence of pore former on porosity and mechanical properties of Ce0.9Gd0.1O1.95 electrolytes for flue gas purification

    DEFF Research Database (Denmark)

    Charlas, Benoit; Schmidt, Cristine Grings; Frandsen, Henrik Lund

    2016-01-01

    than spherical pore formers. An optimum can be found in term of Weibull strength and strain of samples obtained with the various pore formers by considering the dependency on the functional open porosity instead of the total porosity. © 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved....

  9. Pore network and pore scale modeling of reactive transport in porous media

    Science.gov (United States)

    Adler, P. M.; Vu, T. M.; Varloteaux, C.; Bekri, S.

    2012-12-01

    The study of the evolution of a porous medium where a reactive fluid flows is conditioned by the accurate determination of three macroscopic parameters governing the solute displacement, namely the solute velocity, dispersion and mean reaction rate. Of course, a possible application of such studies is CO2 sequestration. This presentation proposes to approach the determination of these parameters by two different ways and to compare them; both are on the pore scale. In the first one called PNM (for pore-network model), a pore-network is extracted from micro tomography images of a real porous medium. This network is composed of spherical pores joined by circular tubes; it is used to calculate transport macroscopic parameters and porosity-permeability evolution during the reactive transport flow as functions of dimensionless numbers representing the reaction and flow rate regimes. The flow is calculated by using Kirchhoff laws. Transport is determined in the asymptotic regime where the solute concentration undergoes an exponential evolution with time. In the second approach called PSM (for pore scale model), the pore-network model is used as a three dimensional medium which is discretized by the Level Set Method. The Stokes equations are solved in order to determine the local flow field and the corresponding permeability. The solute concentration is obtained by solving the local convection-diffusion equation in the 3D pore-network; numerical dispersion is reduced by a Flux Limiting Scheme. Two different geometries of porous media are addressed by both numerical codes. The first pore-network geometry is used to validate the PNM assumptions, whereas the second pore-network is defined for a better understanding of the dominant solute distribution. One of the main results obtained with the first pore-network is the dependence of the concentration profile on the Péclet number Pe in the pore-bodies. When this number increases, one has to switch from an assumption of

  10. Nanometer scale pores similar in size to the entrance of the ribosomal exit cavity are a common feature of large RNAs

    Science.gov (United States)

    Rivas, Mario; Tran, Quyen; Fox, George E.

    2013-01-01

    The highly conserved peptidyl transferase center (PTC) of the ribosome contains an RNA pore that serves as the entrance to the exit tunnel. Analysis of available ribosome crystal structures has revealed the presence of multiple additional well-defined pores of comparable size in the ribosomal (rRNA) RNAs. These typically have dimensions of 1–2 nm, with a total area of ∼100 Å2 or more, and most are associated with one or more ribosomal proteins. The PTC example and the other rRNA pores result from the packing of helices. However, in the non-PTC cases the nitrogenous bases do not protrude into the pore, thereby limiting the potential for hydrogen bonding within the pore. Instead, it is the RNA backbone that largely defines the pore likely resulting in a negatively charged environment. In many but not all cases, ribosomal proteins are associated with the pores to a greater or lesser extent. With the exception of the PTC case, the large subunit pores are not found in what are thought to be the evolutionarily oldest regions of the 23S rRNA. The unusual nature of the PTC pore may reflect a history of being created by hybridization between two or more RNAs early in evolution rather than simple folding of a single RNA. An initial survey of nonribosomal RNA crystal structures revealed additional pores, thereby showing that they are likely a general feature of RNA tertiary structure. PMID:23940386

  11. Pore geometry of ceramic device: The key factor of drug release kinetics

    Directory of Open Access Journals (Sweden)

    Čolović B.

    2013-01-01

    Full Text Available Release kinetics of tigecycline, a potential antibiotic in treatment of osteomyelitis, from calcium hydroxyapatite (CHA, as one of the most important ceramic materials in bone tissue engineering, was investigated in this study. Tigecycline, in solid state, was mixed with CHA powder and the obtained mixture was compressed into tablets using two different pressures. These tablets were immersed in a phosphate-buffered saline solution and tigecycline release was measured by a UV-VIS spectrophotometer. The total release time was 5 or 28 days, depending on the pressure applied during compression. It was shown that there is a close relationship between pore sizes and drug release rate. The drug release kinetics was interpreted on the base of pore sizes and pore size distribution. [Projekat Ministarstva nauke Republike Srbije, br. 172026

  12. Energy conversion device with support member having pore channels

    Science.gov (United States)

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

    2014-01-07

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

  13. Pore-Scale Heterogeneity in the Mineral Distribution and Reactive Surface Area of Porous Rocks

    Science.gov (United States)

    Lai, P. E. P.; Krevor, S. C.

    2015-12-01

    The reactive surface area is an important control on interfacial processes between minerals and aqueous fluids in porous rocks. Spatial heterogeneity in the surface area can lead to complications in modelling reactive transport processes, but quantitative characterisation of this property has been limited. In this paper 3D images obtained using x-ray micro-tomography were used to characterise heterogeneity in surface area in one sandstone and five carbonate rocks. Measurements of average surface area from x-ray imagery were 1-2 orders of magnitude lower than measurements from nitrogen BET. A roughness factor, defined as the ratio of BET surface area to x-ray based surface area, was correlated to the presence of clay or microporosity. Coregistered images of Berea sandstone from x-ray and energy dispersive spectroscopy imagery were used to guide the identification of quartz, K-feldspar, dolomite, calcite and clays in x-ray images. In Berea sandstone, clay and K-feldspar had higher average surface area fractions than their volumetric fractions in the rock. In the Edwards carbonate, however, modal mineral composition correlated with surface area. By sub-sampling digital images, statistical distributions of the surface area were generated at various length scales of subsampling. Comparing these to distributions used in published modelling studies showed that the common practice of leaving surface area and pore volume uncorrelated in a pore leads to unrealistic combinations of surface area and pore volume in the models. We suggest these models adopt a moderate correlation based on observations. In Berea sandstone, constraining ratios of surface area to pore volume to a range of values between that of quartz-lined and five times that of clay-lined spheres appeared sufficient.

  14. Displacement of soil pore water by trichloroethylene

    Science.gov (United States)

    Wershaw, R. L.; Aiken, G.R.; Imbrigiotta, T.E.; Goldberg, M.C.

    1994-01-01

    Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil pore water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter are very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil pore water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil pore water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone.

  15. Silicon pore optics developments and status

    DEFF Research Database (Denmark)

    Bavdaz, Marcos; Wille, Eric; Wallace, Kotska;

    2012-01-01

    Silicon Pore Optics (SPO) is a lightweight high performance X-ray optics technology being developed in Europe, driven by applications in observatory class high energy astrophysics missions. An example of such application is the former ESA science mission candidate ATHENA (Advanced Telescope...... of the SPO technology. The technology development programme has succeeded in maturing the SPO further and achieving important milestones, in each of the main activity streams: environmental compatibility, industrial production and optical performance. In order to accurately characterise the increasing...... performance of this innovative optical technology, the associated X-ray test facilities and beam-lines have been refined and upgraded. © 2012 SPIE....

  16. Viral Subversion of the Nuclear Pore Complex

    Directory of Open Access Journals (Sweden)

    Valerie Le Sage

    2013-08-01

    Full Text Available The nuclear pore complex (NPC acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order to regulate trafficking of viral proteins, genomes and even capsids into and out of the nucleus thus promoting virus replication. The present review examines the different strategies and the specific nucleoporins utilized during viral infections as a means of promoting their life cycle and inhibiting host viral defenses.

  17. Analysis of quantitative pore features based on mathematical morphology

    Institute of Scientific and Technical Information of China (English)

    QI Heng-nian; CHEN Feng-nong; WANG Hang-jun

    2008-01-01

    Wood identification is a basic technique of wood science and industry. Pore features are among the most important identification features for hardwoods. We have used a method based on an analysis of quantitative pore feature, which differs from traditional qualitative methods. We applies mathematical morphology methods such as dilation and erosion, open and close transformation of wood cross-sections, image repairing, noise filtering and edge detection to segment the pores from their background. Then the mean square errors (MSE) of pores were computed to describe the distribution of pores. Our experiment shows that it is easy to classift the pore features into three basic types, just as in traditional qualitative methods, but with the use of MSE of pores. This quantitative method improves wood identification considerably.

  18. Quantifying similarity of pore-geometry in nanoporous materials

    Science.gov (United States)

    Lee, Yongjin; Barthel, Senja D.; Dłotko, Paweł; Moosavi, S. Mohamad; Hess, Kathryn; Smit, Berend

    2017-05-01

    In most applications of nanoporous materials the pore structure is as important as the chemical composition as a determinant of performance. For example, one can alter performance in applications like carbon capture or methane storage by orders of magnitude by only modifying the pore structure. For these applications it is therefore important to identify the optimal pore geometry and use this information to find similar materials. However, the mathematical language and tools to identify materials with similar pore structures, but different composition, has been lacking. We develop a pore recognition approach to quantify similarity of pore structures and classify them using topological data analysis. This allows us to identify materials with similar pore geometries, and to screen for materials that are similar to given top-performing structures. Using methane storage as a case study, we also show that materials can be divided into topologically distinct classes requiring different optimization strategies.

  19. Dendritic silica nanomaterials (KCC-1) with fibrous pore structure possess high DNA adsorption capacity and effectively deliver genes in vitro.

    Science.gov (United States)

    Huang, Xiaoxi; Tao, Zhimin; Praskavich, John C; Goswami, Anandarup; Al-Sharab, Jafar F; Minko, Tamara; Polshettiwar, Vivek; Asefa, Tewodros

    2014-09-16

    The pore size and pore structure of nanoporous materials can affect the materials' physical properties, as well as potential applications in different areas, including catalysis, drug delivery, and biomolecular therapeutics. KCC-1, one of the newest members of silica nanomaterials, possesses fibrous, large pore, dendritic pore networks with wide pore entrances, large pore size distribution, spacious pore volume and large surface area--structural features that are conducive for adsorption and release of large guest molecules and biomacromolecules (e.g., proteins and DNAs). Here, we report the results of our comparative studies of adsorption of salmon DNA in a series of KCC-1-based nanomaterials that are functionalized with different organoamine groups on different parts of their surfaces (channel walls, external surfaces or both). For comparison the results of our studies of adsorption of salmon DNA in similarly functionalized, MCM-41 mesoporous silica nanomaterials with cylindrical pores, some of the most studied silica nanomaterials for drug/gene delivery, are also included. Our results indicate that, despite their relatively lower specific surface area, the KCC-1-based nanomaterials show high adsorption capacity for DNA than the corresponding MCM-41-based nanomaterials, most likely because of KCC-1's large pores, wide pore mouths, fibrous pore network, and thereby more accessible and amenable structure for DNA molecules to diffuse through. Conversely, the MCM-41-based nanomaterials adsorb much less DNA, presumably because their outer surfaces/cylindrical channel pore entrances can get blocked by the DNA molecules, making the inner parts of the materials inaccessible. Moreover, experiments involving fluorescent dye-tagged DNAs suggest that the amine-grafted KCC-1 materials are better suited for delivering the DNAs adsorbed on their surfaces into cellular environments than their MCM-41 counterparts. Finally, cellular toxicity tests show that the KCC-1-based

  20. Impact of Wettability on Pore-Scale Characteristics of Residual Nonaqueous Phase Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Al-Raoush, Riyadh I.; (Southern)

    2009-07-31

    The objective of this paper was to investigate the impact of wettability of porous media on pore-scale characteristics of residual nonaqueous phase liquids (NAPLs). Synchrotron X-ray microtomography was used to obtain high-resolution three-dimensional images of fractionally wet sand systems with mean grain size of 250 {micro}m. Pore-scale characteristics of NAPL blobs such as volume, lengths, interfacial areas, and sphericity index were computed using three-dimensional image processing algorithms. Four systems comprised of 100, 50, 25, and 0% NAPL-wet mass fractions containing the residual NAPL were imaged and analyzed. Findings indicate that spatial variation in wettability of porous media surfaces has a significant impact on pore-scale characteristics of residual NAPL blobs in saturated porous media systems. As the porous media comprises more water-wet surfaces, residual NAPL blobs increase in size and length due to the entrapment at large pore bodies. NAPL-water interfacial areas tend to increase as the NAPL-wet surface fractions increase in the systems. Overall residual NAPL saturations are less in fractionally wet systems and increase as the systems become more NAPL-wet or water-wet.

  1. Hydrophobic polymers modification of mesoporous silica with large pore size for drug release

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Shenmin, E-mail: smzhu@sjtu.edu.c [Shanghai Jiao Tong University, State Key Lab of Metal Matrix Composites (China); Zhang Di; Yang Na [Fudan University, Ministry of Education, Key Lab of Molecular Engineering of Polymers (China)

    2009-04-15

    Mesostructure cellular foam (MCF) materials were modified with hydrophobic polyisoprene (PI) through free radical polymerization in the pores network, and the resulting materials (MCF-PI) were investigated as matrices for drug storage. The successful synthesis of PI inside MCF was characterized by Fourier transform infrared (FT-IR), hydrogen nuclear magnetic resonance ({sup 1}H NMR), X-ray diffraction patterns (XRD) and nitrogen adsorption/desorption measurements. It was interesting to find the resultant system held a relatively large pore size (19.5 nm) and pore volume (1.02 cm{sup 3} g{sup -1}), which would benefit for drug storage. Ibuprofen (IBU) and vancomycin were selected as model drugs and loaded onto unmodified MCF and modified MCF (MCF-PI). The adsorption capacities of these model drugs on MCF-PI were observed increase as compared to that of on pure MCF, due to the trap effects induced by polyisoprene chains inside the pores. The delivery system of MCF-PI was found to be more favorable for the adsorption of IBU (31 wt%, IBU/silica), possibly attributing to the hydrophobic interaction between IBU and PI formed on the internal surface of MCF matrix. The release of drug through the porous network was investigated by measuring uptake and release of IBU.

  2. Simulations of beta-hairpin folding confined to spherical pores using distributed computing.

    Science.gov (United States)

    Klimov, D K; Newfield, D; Thirumalai, D

    2002-06-11

    We report the thermodynamics and kinetics of an off-lattice Go model beta-hairpin from Ig-binding protein confined to an inert spherical pore. Confinement enhances the stability of the hairpin due to the decrease in the entropy of the unfolded state. Compared with their values in the bulk, the rates of hairpin formation increase in the spherical pore. Surprisingly, the dependence of the rates on the pore radius, R(s), is nonmonotonic. The rates reach a maximum at R(s)/R(g,N)(b) approximately equal to 1.5, where R(g,N)(b) is the radius of gyration of the folded beta-hairpin in the bulk. The denatured state ensemble of the encapsulated beta-hairpin is highly structured even at substantially elevated temperatures. Remarkably, a profound effect of confinement is evident even when the beta-hairpin occupies less than a 10th of the sphere volume. Our calculations show that the emergence of substantial structure in the denatured state of proteins in inert pores is a consequence of confinement. In contrast, the structure of the bulk denatured state ensemble depends dramatically on the extent of denaturation.

  3. Linker Installation: Engineering Pore Environment with Precisely Placed Functionalities in Zirconium MOFs.

    Science.gov (United States)

    Yuan, Shuai; Chen, Ying-Pin; Qin, Jun-Sheng; Lu, Weigang; Zou, Lanfang; Zhang, Qiang; Wang, Xuan; Sun, Xing; Zhou, Hong-Cai

    2016-07-20

    Precise placement of multiple functional groups in a highly ordered metal-organic framework (MOF) platform allows the tailoring of the pore environment, which is required for advanced applications. To realize this, we present a comprehensive study on the linker installation method, in which a stable MOF with coordinatively unsaturated Zr6 clusters was employed and linkers bearing different functional groups were postsynthetically installed. A Zr-MOF with inherent missing linker sites, namely, PCN-700, was initially constructed under kinetic control. Twelve linkers with different substituents were then designed to study their effect on MOF formation kinetics and therefore resulting MOF structures. Guided by the geometrical analysis, linkers with different lengths were installed into a parent PCN-700, giving rise to 11 new MOFs and each bearing up to three different functional groups in predefined positions. Systematic variation of the pore volume and decoration of pore environment were realized by linker installation, which resulted in synergistic effects including an enhancement of H2 adsorption capacities of up to 57%. In addition, a size-selective catalytic system for aerobic alcohol oxidation reaction is built in PCN-700 through linker installation, which shows high activity and tunable size selectivity. Altogether, these results exemplify the capability of the linker installation method in the pore environment engineering of stable MOFs with multiple functional groups, giving an unparalleled level of control.

  4. Pore-level mechanics of foam generation and coalescence in the presence of oil.

    Science.gov (United States)

    Almajid, Muhammad M; Kovscek, Anthony R

    2016-07-01

    The stability of foam in porous media is extremely important for realizing the advantages of foamed gas on gas mobility reduction. Foam texture (i.e., bubbles per volume of gas) achieved is dictated by foam generation and coalescence processes occurring at the pore-level. For foam injection to be widely applied during gas injection projects, we need to understand these pore-scale events that lead to foam stability/instability so that they are modeled accurately. Foam flow has been studied for decades, but most efforts focused on studying foam generation and coalescence in the absence of oil. Here, the extensive existing literature is reviewed and analyzed to identify open questions. Then, we use etched-silicon micromodels to observe foam generation and coalescence processes at the pore-level. Special emphasis is placed on foam coalescence in the presence of oil. For the first time, lamella pinch-off as described by Myers and Radke [40] is observed in porous media and documented. Additionally, a new mechanism coined "hindered generation" is found. Hindered generation refers to the role oil plays in preventing the successful formation of a lamella following snap-off near a pore throat.

  5. A study on optimal pore development of modified commercial activated carbons for electrode materials of supercapacitors

    Science.gov (United States)

    Bang, Joon Hyuk; Lee, Hye-Min; An, Kay-Hyeok; Kim, Byung-Joo

    2017-09-01

    This study aimed to understand the impact of CO2 activation of commercial activated carbons (AC) on the changes in pore characteristics and the electrochemical property. The surface structure of manufactured AC was observed with a X-ray diffraction (XRD); the pore characteristics were analyzed at N2/77 K isothermal absorption using the Brunauer-Emmett-Teller (BET) and Dubinin-Radushkevich (DR) equations. In addition, the electrochemical characteristics were analyzed by means of an electrolyte of 1 M (C2H5)4NBF4/propylene carbonate, using a charge/discharge test, cyclic voltammetry (CV), and impedance. The N2/77 K isothermal absorption curve of the manufactured AC falls under Type I in the classification of the International Union of Pure and Applied Chemistry (IUPAC) and was found to largely comprise micropores. The specific surface area increased from 1690 m2/g to 2290 m2/g, and the pore volume grew from 0.80 cm3/g to 1.10 cm3/g. The analysis of electrochemical characteristics also found that the specific capacity increased from 17 F/g to 20 F/g (in a full cell condition). Based on these results, we were able to determine the pore characteristics of commercial AC through an additional activation process, which consequently allowed us to manufacture the AC with an advanced electrochemical property.

  6. Preparation of Granular Red Mud Adsorbent using Different Binders by Microwave Pore - Making and Activation Method

    Science.gov (United States)

    Le, Thiquynhxuan; Wang, Hanrui; Ju, Shaohua; Peng, Jinhui; Zhou, Liexing; Wang, Shixing; Yin, Shaohua; Liu, Chao

    2016-04-01

    In this work, microwave energy is used for preparing a granular red mud (GRM) adsorbent made of red mud with different binders, such as starch, sodium silicate and cement. The effects of the preparation parameters, such as binder type, binder addition ratio, microwave heating temperature, microwave power and holding time, on the absorption property of GRM are investigated. The BET surface area, strength, pore structure, XRD and SEM of the GRM absorbent are analyzed. The results show that the microwave roasting has a good effect on pore-making of GRM, especially when using organic binder. Both the BET surface area and the strength of GRM obtained by microwave heating are significantly higher than that by conventional heating. The optimum conditions are obtained as follows: 6:100 (w/w) of starch to red mud ratio, microwave roasting with a power of 2.6 kW at 500℃ for holding time of 30 min. The BET surface area, pore volume and average pore diameter of GRM prepared at the optimum conditions are 15.58 m2/g, 0.0337 cm3/g and 3.1693 A0, respectively.

  7. Modeling multiphase, multicomponent flows at the pore scale: Wetting phenomena and non-equilibrium phase behavior

    Science.gov (United States)

    Cueto-Felgueroso, L.; Fu, X.; Juanes, R.

    2016-12-01

    The description of multicomponent flows with complex phase behavior remains an open challenge in pore-scale modeling. Darcy-scale general purpose simulators assume local thermodynamic equilibrium, and perform equation-of-state-based calculations to make phase equilibrium predictions; that is, to determine the phase volume fractions and their compositions from overall component mole fractions. What remains unclear is whether the thermodynamic equilibrium assumption is valid given the flow conditions, complex structure of the pore space and characteristic time scales for flow. Diffuse-interface theories of multiphase flow have recently emerged as promising tools to understand and simulate complex processes involving the simultaneous flow of two or more immiscible fluid phases. The common goal in these approaches is to formulate thermodynamically consistent stress tensors and mesoscale balance laws, including the impact of surface tension on the momentum balance, as well as properly tracking interfacial dynamics and mass transfer. We propose a phase-field model of multiphase, multicomponent flow, which we use to address the following research questions: What is the impact of the wetting conditions at the pore scale on upscaled descriptions of multiphase flow? What is the impact of the displacement dynamics, pore space structure and wetting conditions on the phase behavior of multicomponent mixtures? We finally investigate upscaling procedures to incorporate non-equilibrium phase behavior at the continuum scale.

  8. Wettability evaluation of a carbonate reservoir rock from core to pore level

    Energy Technology Data Exchange (ETDEWEB)

    Al-Yousef, H.Y.; Lichaa, P.M.; Al-Kaabi, A.U.; Alpustun, H.

    1995-10-01

    Wettability evaluation was performed during stags of as received, cleaned, and restored states on core samples form a Saudi Arabian carbonate reservoir. The wettability behavior from the chemistry of brine-oil-carbonate rock interaction was found to be neutral to slightly oil-wet. The pore-size distribution obtained from mercury injection data indicated that about 15--20 percent of the pore volume is not accessible to asphaltene particles in the crude oil. Therefore a mixed-wettability state can exist. These results were confirmed by the evaluation of the wettability of the cores using USBM and Amott techniques. The wettability at the pore level was studied using Cryo-Scanning Electron Microscopy. Rock samples were examined at irreducible water and residual oil saturations during cleaned and restored states. At irreducible water saturation, both oil and brine were present in the intergranular macroporosity and intragranular macropores and micropores. At residual oil saturation,oil was found in the form of isolated globules in the cleaned case. After aging, the oil is more loosely distributed in the porosity and generally contacts the pore walls. This indicates an evolution toward oil wetness with aging. These results are in agreement with the changes of wettability indices obtained using USBM technique.

  9. Effect of pore water velocities and solute input methods on chloride transport in the undisturbed soil columns of Loess Plateau

    Science.gov (United States)

    Zhou, BeiBei; Wang, QuanJiu

    2016-04-01

    Studies on solute transport under different pore water velocity and solute input methods in undisturbed soil could play instructive roles for crop production. Based on the experiments in the laboratory, the effect of solute input methods with small pulse input and large pulse input, as well as four pore water velocities, on chloride transport in the undisturbed soil columns obtained from the Loess Plateau under controlled condition was studied. Chloride breakthrough curves (BTCs) were generated using the miscible displacement method under water-saturated, steady flow conditions. Using the 0.15 mol L-1 CaCl2 solution as a tracer, a small pulse (0.1 pore volumes) was first induced, and then, after all the solution was wash off, a large pulse (0.5 pore volumes) was conducted. The convection-dispersion equation (CDE) and the two-region model (T-R) were used to describe the BTCs, and their prediction accuracies and fitted parameters were compared as well. All the BTCs obtained for the different input methods and the four pore water velocities were all smooth. However, the shapes of the BTCs varied greatly; small pulse inputs resulted in more rapid attainment of peak values that appeared earlier with increases in pore water velocity, whereas large pulse inputs resulted in an opposite trend. Both models could fit the experimental data well, but the prediction accuracy of the T-R was better. The values of the dispersivity, λ, calculated from the dispersion coefficient obtained from the CDE were about one order of magnitude larger than those calculated from the dispersion coefficient given by the T-R, but the calculated Peclet number, Pe, was lower. The mobile-immobile partition coefficient, β, decreased, while the mass exchange coefficient increased with increases in pore water velocity.

  10. Developments in glass micro pore optics for x-ray applications

    Science.gov (United States)

    Wallace, Kotska; Collon, Maximilien; Bavdaz, Marcos; Fairbend, Ray; Séguy, Julien; Krumrey, Michael

    2006-06-01

    ESA is developing technologies for x-ray imaging to reduce the mass and volume of future missions. Applications of x-ray optics are foreseen in future planetary x-ray imagers, x-ray timing observatories and in observatories for high-energy astrophysics. With reference to planetary x-ray imagers the use of glass micro-pore material is being investigated. This technology allows the formation of a monolithic, glass structure that can be used to focus x-rays by glancing reflections off the pore walls. A technique to form x-ray focusing plates that contain thousands of square micro-pores has been developed with Photonis. The square pores are formed in a process that fuses blocks of extruded square fibres, which can then be sliced, etched and slumped to form the segment of an optic with a specific radius. A proposed imager would be created from 2 optics, slumped with different radii, and mounted to form an approximation of a Wolter I optic configuration. Reflection can be improved by coating the channel surfaces with a heavy element, such as nickel. Continuing developments have been made to enhance the manufacturing processes and improve the characteristics of the manufactured x-ray focusing plates, such as improved surface roughness and squareness of pore walls, improved pore alignment from fibre stacking through to optic segment slumping and development of pore wall coatings. In order to measure improvements x-ray measurements are performed by ESA and cosine Research BV, using the BESSY-II synchrotron facility four-crystal monochromator beamline of the Physikalisch-Technische Bundesanstalt, on multifibres, sectors and slumped sectors. A probing beam is used to investigate a number of pores to determine x-ray transmission, focussing characteristics as they relate to the overall transmission, x-ray reflectivity of channel walls, radial alignment of fibres, slumping radius and fibre position in a fused block. SEM measurements and microscope inspection have also been used

  11. Atmosphere above a large solar pore

    CERN Document Server

    Sobotka, M; Jurcak, J; Heinzel, P; Del Moro, D

    2013-01-01

    A large solar pore with a granular light bridge was observed on October 15, 2008 with the IBIS spectrometer at the Dunn Solar Telescope and a 69-min long time series of spectral scans in the lines Ca II 854.2 nm and Fe I 617.3 nm was obtained. The intensity and Doppler signals in the Ca II line were separated. This line samples the middle chromosphere in the core and the middle photosphere in the wings. Although no indication of a penumbra is seen in the photosphere, an extended filamentary structure, both in intensity and Doppler signals, is observed in the Ca II line core. An analysis of morphological and dynamical properties of the structure shows a close similarity to a superpenumbra of a sunspot with developed penumbra. A special attention is paid to the light bridge, which is the brightest feature in the pore seen in the Ca II line centre and shows an enhanced power of chromospheric oscillations at 3-5 mHz. Although the acoustic power flux in the light bridge is five times higher than in the "quiet" chr...

  12. Molecular dynamics simulation of flow in pores

    Science.gov (United States)

    Blömer, Jan

    2001-08-01

    The gaseous flow in nano-scale pores is of wide interest for many today's industrial applications, e.g., in microelectronics, nano-mechanical devices (Knudsen compressor) and reaction and adsorption at porous surfaces. This can be seen from a variety of papers of recent RGD Symposia. Furthermore it is possible to separate gases by porous membranes. Although the fundamental problem of all these applications is same, namely the important role of the gas-surface interaction in such small structures, we will primarily concentrate on the separation of different gas species by porous membranes. These membranes are typically very robust (temperature, chemical resistance) because they are made from ceramics which offers new application fields. Porous flow can roughly be divided in several flow regimes by the Knudsen number: From viscous flow to Knudsen diffusion to surface diffusion and up to capillary condensation. A Molecular Dynamics (MD) model for the gas as well as the surface is formulated to investigate the interaction of gas atoms or molecules with internal degrees of freedom and the pore. The MD method seems to be well suited to study these phenomena because it can deal with the high density and the many-body-interactions, which occur during the multilayer adsorption and condensation at the surface, although it is clear that it is limited to a small physical space because of its high computational consumption.

  13. Pore formation in lipid membrane I: Continuous reversible trajectory from intact bilayer through hydrophobic defect to transversal pore.

    Science.gov (United States)

    Akimov, Sergey A; Volynsky, Pavel E; Galimzyanov, Timur R; Kuzmin, Peter I; Pavlov, Konstantin V; Batishchev, Oleg V

    2017-09-22

    Lipid membranes serve as effective barriers allowing cells to maintain internal composition differing from that of extracellular medium. Membrane permeation, both natural and artificial, can take place via appearance of transversal pores. The rearrangements of lipids leading to pore formation in the intact membrane are not yet understood in details. We applied continuum elasticity theory to obtain continuous trajectory of pore formation and closure, and analyzed molecular dynamics trajectories of pre-formed pore reseal. We hypothesized that a transversal pore is preceded by a hydrophobic defect: intermediate structure spanning through the membrane, the side walls of which are partially aligned by lipid tails. This prediction was confirmed by our molecular dynamics simulations. Conversion of the hydrophobic defect into the hydrophilic pore required surmounting some energy barrier. A metastable state was found for the hydrophilic pore at the radius of a few nanometers. The dependence of the energy on radius was approximately quadratic for hydrophobic defect and small hydrophilic pore, while for large radii it depended on the radius linearly. The pore energy related to its perimeter, line tension, thus depends of the pore radius. Calculated values of the line tension for large pores were in quantitative agreement with available experimental data.

  14. The effect of firing temperature on the irreversible expansion, water absorption and pore structure of a brick body during freeze-thaw cycles

    Directory of Open Access Journals (Sweden)

    Mikuláš ŠVEDA

    2013-12-01

    Full Text Available The paper deals with the monitoring of brick body in the process of volumetric freezing and thawing. The samples were fired at temperatures of 900, 1000 and 1060 °C. Attention is focused on monitoring of the irreversible expansion, water absorption and pore structure of a brick body. We found that in all cases the endpoints take place continuously, where the amount firing temperature plays a crucial role. The greatest influence of freeze/thaw cycles on the change of the pore structure was also observed at the lowest temperature. The change of the pore system during the freeze-thaw cycles occurs in such a way, that the pore volume of small pores further decreases and conversely, the pore volume of large pores increases. The knowledge gained can be used not only in the production of new but also in predicting the remaining durability of older clay roofing tiles. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2741

  15. The effect of firing temperature on the irreversible expansion, water absorption and pore structure of a brick body during freeze-thaw cycles

    Directory of Open Access Journals (Sweden)

    Mikuláš ŠVEDA

    2013-12-01

    Full Text Available The paper deals with the monitoring of brick body in the process of volumetric freezing and thawing. The samples were fired at temperatures of 900, 1000 and 1060 °C. Attention is focused on monitoring of the irreversible expansion, water absorption and pore structure of a brick body. We found that in all cases the endpoints take place continuously, where the amount firing temperature plays a crucial role. The greatest influence of freeze/thaw cycles on the change of the pore structure was also observed at the lowest temperature. The change of the pore system during the freeze-thaw cycles occurs in such a way, that the pore volume of small pores further decreases and conversely, the pore volume of large pores increases. The knowledge gained can be used not only in the production of new but also in predicting the remaining durability of older clay roofing tiles. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2741

  16. The effect of synthesis parameters on the geometry and dimensions of mesoporous hydroxyapatite nanoparticles in the presence of 1-dodecanethiol as a pore expander

    Energy Technology Data Exchange (ETDEWEB)

    Bakhtiari, L. [School of Metallurgical and Materials Engineering, Iran University of Science and Technology, Tehran, Narmak 16844 (Iran, Islamic Republic of); Rezaie, H.R., E-mail: hrezaie@iust.ac.ir [School of Metallurgical and Materials Engineering, Iran University of Science and Technology, Tehran, Narmak 16844 (Iran, Islamic Republic of); Javadpour, J. [School of Metallurgical and Materials Engineering, Iran University of Science and Technology, Tehran, Narmak 16844 (Iran, Islamic Republic of); Erfan, M. [Shahid Beheshti University of Medical Sciences, Tehran 6153-14155 (Iran, Islamic Republic of); Shokrgozar, M.A. [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran 13164 (Iran, Islamic Republic of)

    2015-08-01

    Mesoporous hydroxyapatite with different pore diameters and pore volumes were synthesized by the self-assembly method using Cetyltrimethylammonium bromide (CTAB) as the cationic surfactant and 1-dodecanethiol as the pore expander at different micellization pHs, solvent types and surfactant concentrations. Results of field emission scanning electron microscopy (FESEM) showed a decrease in length/diameter ratio of rod-like particles by an increase in micellization pH and also a sphere to rod transition in morphology by an increase in CTAB concentration. Brunauer–Emmett–Teller (BET) surface area and Low angle X-ray diffraction analysis revealed that the optimized mesoporous hydroxyapatite with controlled pore structure can be obtained under basic micellization pH (about 12, pH of complete ionization of 1-dodecanethiol) by using water as the solvent and a high content of cationic surfactant. The results also show that micellization pH has a strong effect on pore structure and changing the pH can shift the mesostructure to a macroporous structure with morphological changes. - Highlights: • Synthesis of mesoporous hydroxyapatite with controlled pore structure • Introduced a facile way to obtain mesoporous hydroxyapatite with high pore volume • Evaluation of morphological changes as a function of synthesis parameters.

  17. Large Mesopore Generation in an Amorphous Silica-Alumina by Controlling the Pore Size with the Gel Skeletal Reinforcement and Its Application to Catalytic Cracking

    Directory of Open Access Journals (Sweden)

    Hiroyuki Nasu

    2012-09-01

    Full Text Available Tetraethoxy orthosilicate (TEOS was used not only as a precursor of silica, but also as an agent which reinforces the skeleton of silica-gel to prepare an aerogel and resultant silica and silica-alumina with large pore size and pore volume. In this gel skeletal reinforcement, the strength of silica aerogel skeleton was enhanced by aging with TEOS/2-propanol mixed solution to prevent the shrink of the pores. When silica aerogel was reinforced by TEOS solution, the pore diameter and pore volume of calcined silica could be controlled by the amount of TEOS solution and reached 30 nm and 3.1 cm3/g. The results from N2 adsorption measurement indicated that most of pores for this silica consisted of mesopores. Silica-alumina was prepared by the impregnation of an aluminum tri-sec-butoxide/2-butanol solution with obtained silica. Mixed catalysts were prepared by the combination of β-zeolite (26 wt% and prepared silica-aluminas with large mesopore (58 wt% and subsequently the effects of their pore sizes on the catalytic activity and the product selectivity were investigated in catalytic cracking of n-dodecane at 500 °C. The mixed catalysts exhibited not only comparable activity to that for single zeolite, but also unique selectivity where larger amounts of branched products were formed.

  18. An emerging pore-making strategy: confined swelling-induced pore generation in block copolymer materials.

    Science.gov (United States)

    Wang, Yong; Li, Fengbin

    2011-05-17

    Block copolymers (BCPs) composed of two or more thermodynamically incompatible homopolymers self-assemble into periodic microdomains. Exposing self-assembled BCPs with solvents selective to one block causes a swelling of the domains composed of this block. Strong swelling in the confinement imposed by the matrix of the other glassy block leads to well-defined porous structures via morphology reconstruction. This confined swelling-induced pore-making process has emerged recently as a new strategy to produce porous materials due to synergic advantages that include extreme simplicity, high pore regularity, involvement of no chemical reactions, no weight loss, reversibility of the pore forming process, etc. The mechanism, kinetics, morphology, and governing parameters of the confined swelling-induced pore-making process in BCP thin films are discussed, and the main applications of nanoporous thin films in the fields of template synthesis, surface patterning, and guidance for the areal arrangements of nanomaterials and biomolecules are summarized. Recent, promising results of extending this mechanism to produce BCP nanofibers or nanotubes and bulk materials with well-defined porosity, which makes this strategy also attractive to researchers outside the nanocommunity, are also presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Computational modeling of electrokinetic transport in random networks of micro-pores and nano-pores

    Science.gov (United States)

    Alizadeh, Shima; Mani, Ali

    2014-11-01

    A reduced order model has been developed to study the nonlinear electrokinetic behaviors emerging in the transport of ionic species through micro-scale and nano-scale porous media. In this approach a porous structure is modeled as a network of long and thin pores. By assuming transport equilibrium in the thin dimensions for each pore, a 1D transport equation is developed in the longitudinal direction covering a wide range of conditions including extreme limits of thick and thin electric double layers. This 1D model includes transport via diffusion, electromigration and wide range of advection mechanisms including pressure driven flow, electroosmosis, and diffusion osmosis. The area-averaged equations governing the axial transport from different pores are coupled at the pore intersections using the proper conservation laws. Moreover, an asymptotic treatment has been included in order to remove singularities in the limit of small concentration. The proposed method provides an efficient framework for insightful simulations of porous electrokinetic systems with applications in water desalination and energy storage. PhD student in Mechanical Engineering, Stanford University. She received her Master's degree in Mechanical Engineering from Stanford at 2013. Her research interests include CFD, high performance computing, and optimization.

  20. Structure and mechanism of peptide-induced membrane pores

    Science.gov (United States)

    Qian, Shuo

    This thesis reports the studies of the structure and mechanism of peptide-induced membrane pores by antimicrobial peptide alamethicin and by a peptide named Baxalpha5, which is derived from Bax protein. Alamethicin is one of best known antimicrobial peptides, which are ubiquitous throughout the biological world. Bax-alpha5 peptide is the pore-forming domain of apoptosis regulator protein Bax, which activates pore formation on outer mitochondrial membrane to release cytochrome c to initiate programmed cell death. Both peptides as well as many other pore-forming peptides, induce pores in membrane, however the structure and mechanism of the pore formation were unknown. By utilizing grazing angle x-ray diffraction, I was able to reconstruct the electron density profile of the membrane pores induced by both peptides. The fully hydrated multiple bilayers of peptide-lipid mixture on solid substrate were prepared in the condition that pores were present, as established previously by neutron in-plane scattering and oriented circular dichroism. At dehydrated conditions, the inter bilayer distance of the sample shortened and the interactions between bilayers caused the membrane pores to become long-ranged correlated and formed a periodically ordered lattice of rhombohedral symmetry, so that x-ray diffraction can be applied. To help solving the phase problem of diffraction, a brominated lipid was used and multi-wavelength anomalous diffraction was performed below the bromine K-edge. The reconstructed electron density profiles unambiguously revealed that the alamethicin-induced membrane pore is of barrel-stave type, while the Bax-alpha5 induced pore is of lipidic toroidal (wormhole) type. The underlying mechanism of pore formation was resolved by observing the time-dependent process of pore formation in vesicles exposed to Bax-alpha5 solutions, as well as the membrane thinning experiment. This demonstrated that Bax-alpha5 exhibited the same sigmoidal concentration dependence as

  1. The Effects of Swelling and Porosity Change on Capillarity: DEM Coupled with a Pore-Unit Assembly Method.

    Science.gov (United States)

    Sweijen, Thomas; Nikooee, Ehsan; Hassanizadeh, S Majid; Chareyre, Bruno

    In this study, a grain-scale modelling technique has been developed to generate the capillary pressure-saturation curves for swelling granular materials. This model employs only basic granular properties such as particles size distribution, porosity, and the amount of absorbed water for swelling materials. Using this model, both drainage and imbibition curves are directly obtained by pore-scale simulations of fluid invasion. This allows us to produce capillary pressure-saturation curves for a large number of different packings of granular materials with varying porosity and/or amount of absorbed water. The algorithm is based on combining the Discrete Element Method for generating different particle packings with a pore-unit assembly approach. The pore space is extracted using a regular triangulation, with the centres of four neighbouring particles forming a tetrahedron. The pore space within each tetrahedron is referred to as a pore unit. Thus, the pore space of a particle packing is represented by an assembly of pore units for which we construct drainage and imbibition capillary pressure-saturation curves. A case study on Hostun sand is conducted to test the model against experimental data from literature and to investigate the required minimum number of particles to have a Representative Elementary Volume. Then, the capillary pressure-saturation curves are constructed for Absorbent Gelling Material particles, for different combinations of porosity values and amounts of absorbed water. Each combination yields a different configuration of pore units, and thus distinctly different capillary pressure-saturation curves. All these curves are shown to collapse into one curve for drainage and one curve for imbibition when we normalize capillary pressure and saturation values. We have developed a formula for the Van Genuchten parameter [Formula: see text] (which is related to the inverse of the entry pressure) as a function of porosity and the amount of absorbed water.

  2. Ground Organic Monolith Particles Having a Large Volume of Macropores as Chromatographic Separation Media

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin Wook; Ali, Faiz; Kim, Yune Sung; Cheong, Won Jo [Inha Univ., Incheon (Korea, Republic of)

    2014-07-15

    A reaction mixture was developed for formation of soft organic monolith that was easily smashed, rinsed, refluxed, filtered, and dried to give monolith particles having high pore volume of macropores. This phase was almost without mesopores. The reaction mixture was composed of methacrylic acid, ethylene glycol dimethacrylate, polyethylene glycol (porogen), and an initiator in a mixed solvent of toluene and isooctane. The selection of porogen and its amount was carefully carried out to obtain the optimized separation efficiency of the resultant phase. The median macropore size was 1.6 μm, and the total pore volume was 3.0-3.4 mL/g. The median particle size (volume based) was 15 μm, and the range of particle size distribution was very broad. Nevertheless the column (1 Χ 300 mm) packed with this phase showed good separation efficiency (N∼10,000-16,000) comparable to that of a commercial column packed with 5 μm C18 silica particles.

  3. Visualizing and Quantifying Bioaccessible Pores in Field-Aged Petroleum Hydrocarbon-Contaminated Clay Soils Using Synchrotron-based X-ray Computed Tomography

    Science.gov (United States)

    Chang, W.; Kim, J.; Zhu, N.; McBeth, J. M.

    2015-12-01

    Microbial hydrocarbon degradation is environmentally significant and applicable to contaminated site remediation practices only when hydrocarbons (substrates) are physically bioaccessible to bacteria in soil matrices. Powerful X-rays are produced by synchrotron radiation, allowing for bioaccessible pores in soil (larger than 4 microns), where bacteria can be accommodated, colonize and remain active, can be visualized at a much higher resolution. This study visualized and quantified such bioaccessible pores in intact field-aged, oil-contaminated unsaturated soil fractions, and examined the relationship between the abundance of bioaccessible pores and hydrocarbon biodegradation. Using synchrotron-based X-ray Computed Tomography (CT) at the Canadian Light Source, a large dataset of soil particle characteristics, such as pore volumes, surface areas, number of pores and pore size distribution, was generated. Duplicate samples of five different soil fractions with different soil aggregate sizes and water contents (13, 18 and 25%) were examined. The method for calculating the number and distribution of bioaccessible pores using CT images was validated using the known porosity of Ottawa sand. This study indicated that the distribution of bioaccessible pore sizes in soil fractions are very closely related to microbial enhancement. A follow-up aerobic biodegradation experiment for the soils at 17 °C (average site temperature) over 90 days confirmed that a notable decrease in hydrocarbon concentrations occurred in soils fractions with abundant bioaccessible pores and with a larger number of pores between 10 and 100 μm. The hydrocarbon degradation in bioactive soil fractions was extended to relatively high-molecular-weight hydrocarbons (C16-C34). This study provides quantitative information about how internal soil pore characteristics can influence bioremediation performance.

  4. Study on pore structure properties of steam activated biomass chars

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Tong; Lu, Fei; Wang, Qinchao; Lu, Ping [Nanjing Normal Univ. (China). School of Energy and Mechanical Engineering

    2013-07-01

    Wheat straw and rice husk chars were prepared in a fixed bed reactor at different pyrolysis temperatures (673, 873 and 1,073K) and different pyrolysis procedure. The steam activated chars were also prepared in a fixed bed reactor at the following conditions: activation temperature is 1,073K, the flow rate of N{sub 2} is 5L/min, and N{sub 2} and H{sub 2}O molar ratio is 1:1. The specific surface area, pore structure and micro-morphology of different kinds of prepared biomass chars were measured by NOVA1000e analysis instrument and JSM-5610LV scanning electron microscopy (SEM), respectively. Results indicated that the internal structure was improved significantly by steam activation through enlarging the specific surface area and enriching the porosity. The wheat straw char prepared by both rapid pyrolysis at 873K and activation by steam is better than others, whose DR surface area increases from 3.10 to 1099.99m{sup 2}/g. The N{sub 2} adsorption volume of steam activated biomass chars has been significant promoted.

  5. Exact calculation of the tortuosity in disordered linear pores in the Knudsen regime.

    Science.gov (United States)

    Russ, Stefanie

    2009-12-01

    The squared reciprocal tortuosity kappa-2=D/D0 for linear diffusion on lattices and in pores in the Knudsen regime is calculated analytically for a large variety of disordered systems. Here, D0 and D are the self-diffusion coefficients of the smooth and the corresponding disordered system, respectively. To this end, a building-block principle is developed that composes the systems into substructures without cross correlations between them. It is shown how the solutions of the different building blocks can be combined to gain D/D0 for pores of high complexity from the geometrical properties of the systems, i.e., from the volumes of the different substructures. As a test, numerical simulations are performed that agree perfectly with the theory.

  6. Three-dimensional characterization of pores in Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    Márcia Regina Baldissera

    2011-03-01

    Full Text Available The direct three-dimensional characterization of opaque materials through serial sectioning makes possible to visualize and better quantify a material microstructure, using classical metallographic techniques coupled with computer-aided reconstruction. Titanium alloys are used as biomaterials for bone implants because of its excellent mechanical properties, biocompatibility and enhanced corrosion resistance. The Ti-6Al-4V alloy (in wt. (% with porous microstructure permits the ingrowths of new-bone tissues improving the fixation bone/implant. This is important to understand connectivity, morphology and spatial distribution of pores in microstructure. The Ti-6Al-4V alloy compacts were produced by powder metallurgy and sintered at three distinct temperatures (1250, 1400 and 1500 °C to obtain distinct microstructures in terms of residual porosity. The visualization of the reconstructed 3D microstructure provides a qualitative and quantitative analysis of the porosity of Ti6Al4V alloy (volume fraction and pore morphology.

  7. Biological Chitin-MOF Composites with Hierarchical Pore Systems for Air-Filtration Applications.

    Science.gov (United States)

    Wisser, Dorothea; Wisser, Florian M; Raschke, Silvia; Klein, Nicole; Leistner, Matthias; Grothe, Julia; Brunner, Eike; Kaskel, Stefan

    2015-10-19

    Metal-organic frameworks (MOFs) are promising materials for gas-separation and air-filtration applications. However, for these applications, MOF crystallites need to be incorporated in robust and manageable support materials. We used chitin-based networks from a marine sponge as a non-toxic, biodegradable, and low-weight support material for MOF deposition. The structural properties of the material favor predominant nucleation of the MOF crystallites at the inside of the hollow fibers. This composite has a hierarchical pore system with surface areas up to 800 m(2)  g(-1) and pore volumes of 3.6 cm(3)  g(-1) , allowing good transport kinetics and a very high loading of the active material. Ammonia break-through experiments highlight the accessibility of the MOF crystallites and the adsorption potential of the composite indicating their high potential for filtration applications for toxic industrial gases.

  8. Single hepatitis-B virus core capsid binding to individual nuclear pore complexes in Hela cells.

    Science.gov (United States)

    Lill, Yoriko; Lill, Markus A; Fahrenkrog, Birthe; Schwarz-Herion, Kyrill; Paulillo, Sara; Aebi, Ueli; Hecht, Bert

    2006-10-15

    We investigate the interaction of hepatitis B virus capsids lacking a nuclear localization signal with nuclear pore complexes (NPCs) in permeabilized HeLa cells. Confocal and wide-field optical images of the nuclear envelope show well-spaced individual NPCs. Specific interactions of capsids with single NPCs are characterized by extended residence times of capsids in the focal volume which are characterized by fluorescence correlation spectroscopy. In addition, single-capsid-tracking experiments using fast wide-field fluorescence microscopy at 50 frames/s allow us to directly observe specific binding via a dual-color colocalization of capsids and NPCs. We find that binding occurs with high probability on the nuclear-pore ring moiety, at 44 +/- 9 nm radial distance from the central axis.

  9. Pore structure and surface area of silica SBA-15: influence of washing and scale-up

    Directory of Open Access Journals (Sweden)

    Jörg P. Thielemann

    2011-02-01

    Full Text Available The removal of the surfactant (EO20PO70EO20 by washing before final calcination is a critical step in the synthesis of silica SBA-15. In contrast to washing with pure water or ethanol, washing with water and ethanol may, depending on the quantity of solvent used, alter the homogeneity and order of the pores, but also lead to an increase of the surface area of SBA-15. A reduction of solvent volume and a controlled washing protocol allow the synthesis of high surface area SBA-15 materials with a narrow monomodal pore size distribution. For larger batch sizes the influence of the quantity of solvent on the quality of the SBA-15 is reduced.

  10. Optimizing the Pore Structure of Bio-Based ACFs through a Simple KOH–Steam Reactivation

    Directory of Open Access Journals (Sweden)

    Yuxiang Huang

    2016-05-01

    Full Text Available Highly microporous bio-based activated carbon fibers (ACFs were prepared through a simple reactivation method. Sawdust, as the starting material, was liquefied and melt-spun to produce the precursor fibers. Then, the precursor fibers were activated by KOH and reactivated by steam. By varying the conditions of the two activation processes, the formation mechanism of the pore structure was studied, and the result showed that steam reactivation has a positive effect on the development of microporosity. The sample with the optimal condition exhibited the highest specific surface area of 2578 m2·g−1 as well as the largest pore volume of 1.425 cm3·g−1, where micropores contributed 70.3%. Due to its excellent texture properties, the ACF exhibited a high adsorption capacity of 1934 mg/g for iodine.

  11. New insights to pore space morphologies in Boom Clay - results from 2D BIB-SEM investigations and mercury injection porosimetry

    Science.gov (United States)

    Hemes, S.; Desbois, G.; Urai, J. L.

    2012-04-01

    BIB-SEM investigations on Boom Clay (Mol-Dessel reference site for radioactive waste disposal, Belgium) of different grain sizes yield new insights to pore space morphologies and pore-size distributions down to the resolution of state-of-the-art SEM. Non-clay minerals embedded into a clay matrix form the overall fabric of the different samples investigated. We identified four main porous mineral phases: clay, pyrite, mica and fossils. Regardless of the origin and the grain-size distribution of samples, characteristic pore morphologies were found for each different mineral phase. Our approach allows segmenting pores with a practical pore resolution of 25-30 nm in pore size (equivalent radius, ER) resulting in total porosities of 10-20 % and log-normal pore-size distributions at the scale of observation. Detailed studies of segmented porosities within the clay matrices point to a power-law distribution of pore-areas over three orders of magnitude, interpreted as self-similarity of the pore space. Moreover, two classes of pore-sizes were distinguished within the clay-matrix: biggest pores were found within the first 100 nm from non-clay mineral grain-boundaries, whereas pores smaller than 100 nm (ER) are homogeneously distributed within the clay matrix. Our calculations show clearly that the median pore-size value of the biggest pores is linked to the grain size parameter, which suggests that the grain- size and the amount of non-clay minerals is controlling the contribution of the largest pore-size fraction to the overall porosity. Bulk porosities measured by mercury injection porosimetry (MIP) are between 26-33 %. The comparison of our microstructural investigations inferred by BIB-SEM with MIP data, indicates that a significant pore fraction is not detected by using the BIB-SEM method (about 10-15 % of the total porosity), corresponding to pores smaller than 30 nm (ER). However, the extrapolation of power-law pore-size distributions, inferred for pores within the

  12. Pore size matters for potassium channel conductance

    Science.gov (United States)

    Moldenhauer, Hans; Pincuntureo, Matías

    2016-01-01

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

  13. Silicon pore optics development for ATHENA

    Science.gov (United States)

    Collon, Maximilien J.; Vacanti, Giuseppe; Günther, Ramses; Yanson, Alex; Barrière, Nicolas; Landgraf, Boris; Vervest, Mark; Chatbi, Abdelhakim; Beijersbergen, Marco W.; Bavdaz, Marcos; Wille, Eric; Haneveld, Jeroen; Koelewijn, Arenda; Leenstra, Anne; Wijnperle, Maurice; van Baren, Coen; Müller, Peter; Krumrey, Michael; Burwitz, Vadim; Pareschi, Giovanni; Conconi, Paolo; Christensen, Finn E.

    2015-09-01

    The ATHENA mission, a European large (L) class X-ray observatory to be launched in 2028, will essentially consist of an X-ray lens and two focal plane instruments. The lens, based on a Wolter-I type double reflection grazing incidence angle design, will be very large (~ 3 m in diameter) to meet the science requirements of large effective area (1-2 m2 at a few keV) at a focal length of 12 m. To meet the high angular resolution (5 arc seconds) requirement the X-ray lens will also need to be very accurate. Silicon Pore Optics (SPO) technology has been invented to enable building such a lens and thus enabling the ATHENA mission. We will report in this paper on the latest status of the development, including details of X-ray test campaigns.

  14. Silicon pore optics for the ATHENA telescope

    Science.gov (United States)

    Collon, Maximilien J.; Vacanti, Giuseppe; Günther, Ramses; Yanson, Alex; Barriere, Nicolas; Landgraf, Boris; Vervest, Mark; Chatbi, Abdelhakim; van der Hoeven, Roy; Beijersbergen, Marco W.; Bavdaz, Marcos; Wille, Eric; Shortt, Brian; Haneveld, Jeroen; Koelewijn, Arenda; van Baren, Coen; Eigenraam, Alexander; Müller, Peter; Krumrey, Michael; Burwitz, Vadim; Pareschi, Giovanni; Conconi, Paolo; Massahi, Sonny; Christensen, Finn E.; Valsecchi, Giuseppe

    2016-07-01

    Silicon Pore Optics is a high-energy optics technology, invented to enable the next generation of high-resolution, large area X-ray telescopes such as the ATHENA observatory, a European large (L) class mission with a launch date of 2028. The technology development is carried out by a consortium of industrial and academic partners and focuses on building an optics with a focal length of 12 m that shall achieve an angular resolution better than 5". So far we have built optics with a focal length of 50 m and 20 m. This paper presents details of the work carried out to build silicon stacks for a 12 m optics and to integrate them into mirror modules. It will also present results of x-ray tests taking place at PTB's XPBF with synchrotron radiation and the PANTER test facility.

  15. Distributed Pore Chemistry in Porous Organic Polymers

    Science.gov (United States)

    Koontz, Steven L. (Inventor)

    1999-01-01

    A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge. wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions. and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

  16. Evaluating transport in irregular pore networks

    CERN Document Server

    Klimenko, Dimitri A; Klimenko, Alexander Y; 10.1103/PhysRevE.86.011112

    2012-01-01

    A general approach for investigating transport phenomena in porous media is presented. This approach has the capacity to represent various kinds of irregularity in porous media without the need for excessive detail or computational effort. The overall method combines a generalized Effective Medium Approximation (EMA) with a macroscopic continuum model in order to derive a transport equation with explicit analytical expressions for the transport coefficients. The proposed form of the EMA is an anisotropic and heterogeneous extension of Kirkpatrick's EMA [Rev. Mod. Phys. 45, 574 (1973)] which allows the overall model to account for microscopic alterations in connectivity (with the locations of the pores and the orientation and length of the throat) as well as macroscopic variations in transport properties. A comparison to numerical results for randomly generated networks with different properties is given, indicating the potential for this methodology to handle cases that would pose significant difficulties to ...

  17. Factors Determining the Pore Shape in Polycarbonate Track Membranes

    CERN Document Server

    Apel, P Yu; Orelovich, O L; Akimenko, S N; Sartowska, B; Dmitriev, S N

    2004-01-01

    The process of pore formation in ion-irradiated polycarbonate films on treatment with alkali solutions in the presence of a surfactant is studied. It is found that the pore shape depends on both the structure of the initial films and the peculiarities of the interaction of the surfactant with the polymer surface and the transport of the surfactant into tracks. Due to heterogeneity of the films the cross-section of a track pore channel changes along its length. The presence of the surfactant results in a further effect. Surfactant molecules adsorb on the polymer surface at the pore entries and reduce the etch rate which leads to formation of cigar-like pore channels. The use of surfactant as a component of chemical etchant enables one to control the pore shape in track membranes thus optimizing their retention and permeation characteristics.

  18. Experimental study on pore water pressure dissipation of mucky soil

    Institute of Scientific and Technical Information of China (English)

    Xianwei ZHANG; Changming WANG; Junxia LI; Bin WANG

    2008-01-01

    Pore water pressure has an important influence on mechanical properties of soil. The authors studied the characteristics of pore water pressure dissipating of mucky soil under consolidated-drained condition by using refitted triaxial instrument and analyzed the variation of pore pressure coefficient with consolidation pressure. The results show that the dissipating of pore water pressure behaves in different ways depends on different styles of loading. What is more, the pore water pressure coefficient of mucky soil is less than 1. As the compactness of soil increases and moisture content reduces, the value of B reduces. There is a staggered dissipating in the process of consolidation, in which it is a mutate point when U/P is 80%. It is helpful to establish the pore water pressure model and study the strength-deformation of soil in process of consolidation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Apel, P.Yu., E-mail: apel@nrmail.jinr.ru [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna (Russian Federation); Dubna International University, Universitetskaya Str. 19, 141980 Dubna (Russian Federation); Ivanov, O.M.; Lizunov, N.E.; Mamonova, T.I.; Nechaev, A.N. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna (Russian Federation); Olejniczak, K. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna (Russian Federation); Faculty of Chemistry, Nicolaus Copernicus University, Gagarina Str. 7, 87-100 Torun (Poland); Vacik, J. [Nuclear Physics Institute, ASCR, v.v.i., 25068 Řež (Czech Republic); Dmitriev, S.N. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna (Russian Federation)

    2015-12-15

    Ion track membranes (ITM) have attracted significant interest over the past two decades due to their numerous applications in physical, biological, chemical, biochemical and medical experimental works. A particular feature of ITM technology is the possibility to fabricate samples with a predetermined number of pores, including single-pore membranes. The present report describes a procedure that allowed for the production of multi-, oligo- and single-pore membranes using a continuous ion beam from an IC-100 cyclotron. The beam was scanned over a set of small diaphragms, from 17 to ∼1000 μm in diameter. Ions passed through the apertures and impinged two sandwiched polymer foils, with the total thickness close to the ion range in the polymer. The foils were pulled across the ion beam at a constant speed. The ratio between the transport speed and the scanning frequency determined the distance between irradiation spots. The beam intensity and the aperture diameters were adjusted such that either several, one or no ions passed through the diaphragms during one half-period of scanning. After irradiation, the lower foil was separated from the upper foil and was etched to obtain pores 6–8 μm in diameter. The pores were found using a color chemical reaction between two reagents placed on opposite sides of the foil. The located pores were further confirmed using SEM and optical microscopy. The numbers of tracks in the irradiation spots were consistent with the Poisson statistics. Samples with single or few tracks obtained in this way were employed to study fine phenomena in ion track nanopores.

  20. Pore Structure Characteristics and Permeability of Deep Sedimentary Rocks Determined by Mercury Intrusion Porosimetry

    Institute of Scientific and Technical Information of China (English)

    Na Zhang; Manchao He; Bo Zhang; Fengchao Qiao; Hailong Sheng; Qinhong Hu

    2016-01-01

    Pore structure characteristics of rock are a great concern for researchers and practitio-ners in rock mechanics and rock engineering fields. In this study, mercury intrusion porosimetry (MIP) was used to measure pore size distribution, as well as several important index parameters of pore structure, for seven common types of deep sedimentary rocks with a total of fifty rock samples. Results show a similar pore size distribution pattern of the rock samples in the same lithological group, but remarkable differences among different lithological groups. Among seven investigated rock types, mudstone has the smallest porosity of 3.37%, while conglomerate has the largest value of 18.8%. It is also found that the porosity of rock types with finer grain size is lower than those with coarser grain size. Meanwhile, a comparison of frequency distribution at ten intervals of pore-throat diameter among seven types of sedimentary rocks reveals that different rock types have different dominant pore-size ranges. Furthermore, permeability of the investigated sedimentary rock samples was derived based on MIP data using reported theoretical equations. Among seven rock types, mudstone has the lowest averaged permeability (3.64×10-6mD) while conglomerate has the highest one (8.59×10-4 mD). From mudstone to conglomerate, rock permeability increases with an increase of grain size, with only an exception of siltstone which has a relatively larger porosity value. Finally, regression analysis show that there is a good fitting (R2=0.95) between permeability and porosity which could be easily used to derive reliable permeability values of similar kinds of engineering rocks.

  1. Vapor intrusion in soils with multimodal pore-size distribution

    OpenAIRE

    Alfaro Soto Miguel; Hung Kiang Chang

    2016-01-01

    The Johnson and Ettinger [1] model and its extensions are at this time the most widely used algorithms for estimating subsurface vapor intrusion into buildings (API [2]). The functions which describe capillary pressure curves are utilized in quantitative analyses, although these are applicable for porous media with a unimodal or lognormal pore-size distribution. However, unaltered soils may have a heterogeneous pore distribution and consequently a multimodal pore-size distribution [3], which ...

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

    Directory of Open Access Journals (Sweden)

    Doron Kabaso

    2012-01-01

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

  3. Enzyme screening with synthetic multifunctional pores: Focus on biopolymers

    Science.gov (United States)

    Sordé, Nathalie; Das, Gopal; Matile, Stefan

    2003-01-01

    This report demonstrates that a single set of identical synthetic multifunctional pores can detect the activity of many different enzymes. Enzymes catalyzing either synthesis or degradation of DNA (exonuclease III or polymerase I), RNA (RNase A), polysaccharides (heparinase I, hyaluronidase, and galactosyltransferase), and proteins (papain, ficin, elastase, subtilisin, and pronase) are selected to exemplify this key characteristic of synthetic multifunctional pore sensors. Because anionic, cationic, and neutral substrates can gain access to the interior of complementarily functionalized pores, such pores can be the basis for very user-friendly screening of a broad range of enzymes. PMID:14530413

  4. Pore-size-distribution of cationic polyacrylamide hydrogels. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, M.; Prausnitz, J.M.

    1992-06-01

    The pore size distribution of a AAm/MAPTAC (acrylamide copolymerized with (3-methacrylamidopropyl)trimethylammonium chloride) hydrogel was investigated using Kuga`s mixed-solute-exclusion method, taking into account the wall effect. A Brownian-motion model is also used. Results show the feasibility of determining pore-size distribution of porous materials using the mixed-solute-exclusion method in conjunction with solution of the Fredholm equation; good agreement was obtained with experiment, even for bimodal pore structures. However, different pore size distributions were calculated for the two different probe-solutes (Dextran and poly(ethylene glycol/oxide)). Future work is outlined. 32 figs, 25 refs.

  5. Pore-size-distribution of cationic polyacrylamide hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, M.; Prausnitz, J.M.

    1992-06-01

    The pore size distribution of a AAm/MAPTAC (acrylamide copolymerized with (3-methacrylamidopropyl)trimethylammonium chloride) hydrogel was investigated using Kuga's mixed-solute-exclusion method, taking into account the wall effect. A Brownian-motion model is also used. Results show the feasibility of determining pore-size distribution of porous materials using the mixed-solute-exclusion method in conjunction with solution of the Fredholm equation; good agreement was obtained with experiment, even for bimodal pore structures. However, different pore size distributions were calculated for the two different probe-solutes (Dextran and poly(ethylene glycol/oxide)). Future work is outlined. 32 figs, 25 refs.

  6. Ultrafast laser fabrication of submicrometer pores in borosilicate glass.

    Science.gov (United States)

    An, Ran; Uram, Jeffrey D; Yusko, Erik C; Ke, Kevin; Mayer, Michael; Hunt, Alan J

    2008-05-15

    We demonstrate rapid fabrication of submicrometer-diameter pores in borosilicate glass using femtosecond laser machining and subsequent wet-etch techniques. This approach allows direct and repeatable fabrication of high-quality pores with diameters of 400-800 nm. Such small pores coupled with the desirable electrical and chemical properties of glass enable sensitive resistive-pulse analysis to determine the size and concentration of macromolecules and nanoparticles. Plasma-enhanced chemical vapor deposition allows further reduction of pore diameters to below 300 nm.

  7. Relationship between elastic moduli and pore radius in clay aggregates

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2011-01-01

    Available experimental data on elastic velocities of clay-air mixtures and clay-brine mixtures as a function of porosity are re-interpreted. Pore radius as calculated from porosity and specific surface measured by BET seems to be the factor controlling stiffness of these un-cemented sediments....... For each of the two pore fluids: air or brine smectitic clay and kaolinitic clay seem to have similar power law relationships between a given elastic modulus and pore radius. These results indicate that pore radius and thus permeability of shale in the depth interval of mechanical compaction may...

  8. Tension-induced vesicle fusion: pathways and pore dynamics

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2008-01-01

    and eventually opens a pore to complete the fusion process. In pathway II, at higher tension, a stalk is formed during the fusion process that is then transformed by transmembrane pore formation into a fusion pore. Whereas the latter pathway II resembles stalk pathways as observed in other simulation studies...... fusion time on membrane tension implies that the fusion process is completed by overcoming two energy barriers with scales of 13kBT and 11kBT. The fusion pore radius as a function of time has also been extracted from the simulations, and provides a quantitative measure of the fusion dynamics which...

  9. Development of an In Situ Raman Probe for Pore Water Geochemistry

    Science.gov (United States)

    Walz, P. M.; Zhang, X.; Hester, K.; Kirkwood, W. J.; Ussler, W.; Peltzer, E. T.; Brewer, P. G.

    2009-12-01

    Scientists and engineers at the Monterey Bay Aquarium Research Institute have developed a ROV-deployable sampling probe utilizing laser Raman spectroscopy for study of sediment pore water geochemistry. The Raman technique has already been used with deep sea ROV platforms successfully performing in situ measurement on targets of scientific interest including gas and hydrothermal vent fluids, and complex gas hydrates. However, in situ measurement of sediment pore water geochemistry by laser Raman methods has so far been an intractable problem because sediment particles strongly fluorescence and insufficient amounts of pore water can be extracted before filters become occluded by sediment particles. Our design incorporates a series of novel elements into a slender 35-cm-long probe that can be inserted into sediment using an ROV manipulator to obtain concentration profiles. Pore water is drawn through a 10-μm stainless steel filter that forms the probe tip into a low volume sample chamber (0.1 mL) using a small hydraulic pump controlled by the ROV. The pump is also used for flushing and clearing filter surfaces. The sampling process is repeated as we proceed incrementally deeper into the sediment. Light (532 nm) from a Raman laser system mounted on the ROV is conveyed by a fiber optic cable to the probe head and focused within the center of the sample chamber through a sapphire-windowed optical cell. Control of the Raman system and spectra acquisition are performed onboard the ship via a laptop computer in the ROV control room. Advantages of this rapid mode of detection include measurement of sulfate gradients in near-seafloor sediments at a vertical scale not easily obtainable using traditional coring and extraction techniques, direct measurement of the dissolved sulfide species H2S and HS-, and measurement of dissolved methane without incurring substantial degassing during core recovery. The chemical measurements are made quantitative by calculating an intensity

  10. Graphite and PMMA as pore formers for thermoplastic extrusion of porous 3Y-TZP oxygen transport membrane supports

    DEFF Research Database (Denmark)

    Bjørnetun Haugen, Astri; Gurauskis, Jonas; Kaiser, Andreas

    2016-01-01

    with gas permeability exceeding the target of 10−14m2 are obtained. In the temperature range 1250–1400°C the support gas permeability is insensitive to the sintering temperature, and the feedstocks shrink more than 15% during sintering, making them ideal for co-sintering with functional OTM layers......A gas permeable porous support is a crucial part of an asymmetric oxygen transport membrane (OTM). Here, we develop feedstocks for thermoplastic extrusion of tubular, porous 3Y-TZP (partially stabilized zirconia polycrystals, (Y2O3)0.03(ZrO2)0.97)) ceramics, using graphite and/or polymethyl...... methacrylate (PMMA) as pore formers. The influence of pore former content and type, 3Y-TZP particle size and support sintering temperature on the microstructure, porosity and gas permeability were studied. Using at least 40 vol% pore former, consisting of graphite and PMMA in the volume ratio 2:1, tubes...

  11. Testing Occam's razor to characterize high-order connectivity in pore networks of granular media: Feature selection in machine learning

    Science.gov (United States)

    van der Linden, Joost; Tordesillas, Antoinette; Narsilio, Guillermo

    2017-06-01

    A perennial challenge for the characterization and modelling of phenomena involving granular media is that the internal connectivity of, and interactions between, the pores and the particles exhibit hallmarks of complexity: multi-scale and nonlinear interactions that lead to a plethora of patterns at the mesoscale, including fluid flow patterns that ultimately render a permeability of the granular media at the macroscale. A multitude of physical parameters exist to characterize geometry and structure, including pore/particle shape, volume and surface area, while a rich class of complex network parameters quantifies internal connectivity of the pore and particles in the material. A large collection of such variables is likely to exhibit a high degree of redundancy. Here we demonstrate how to use feature selection in machine learning theory to identify the most informative and non-redundant, yet parsimonious set of features that optimally characterizes the interstitial flow properties of porous, granular media, e.g., permeability, from high resolution data.

  12. Rock Physics of Reservoir Rocks with Varying Pore Water Saturation and Pore Water Salinity

    DEFF Research Database (Denmark)

    Katika, Konstantina

    be performed on specific geological structures and why it is sometimes successful; has yet to be established. The presence of both oil and water in the pore space, several different ions present in the injected water that contact the pore walls, possible changes in the fluid wetting the surface of the grains......Advanced waterflooding (injection of water with selective ions in reservoirs) is a method of enhanced oil recovery (EOR) that has attracted the interest of oil and gas companies that exploit the Danish oil and gas reservoirs. This method has been applied successfully in oil reservoirs...... and in the Smart Water project performed in a laboratory scale in order to evaluate the EOR processes in selected core plugs. A major step towards this evaluation is to identify the composition of the injected water that leads to increased oil recovery in reservoirs and to define changes in the petrophysical...

  13. Entropy of Shortest Distance (ESD as Pore Detector and Pore-Shape Classifier

    Directory of Open Access Journals (Sweden)

    Klaudia Oleschko

    2013-06-01

    Full Text Available The entropy of shortest distance (ESD between geographic elements (“elliptical intrusions”, “lineaments”, “points” on a map, or between "vugs", "fractures" and "pores" in the macro- or microscopic images of triple porosity naturally fractured vuggy carbonates provides a powerful new tool for the digital processing, analysis, classification and space/time distribution prognostic of mineral resources as well as the void space in carbonates, and in other rocks. The procedure is applicable at all scales, from outcrop photos, FMI, UBI, USI (geophysical imaging techniques to micrographs, as we shall illustrate through some examples. Out of the possible applications of the ESD concept, we discuss in details the sliding window entropy filtering for nonlinear pore boundary enhancement, and propose this procedure as unbiased thresholding technique.

  14. Pore morphologies of root induced biopores from single pore to network scale investigated by XRCT

    Science.gov (United States)

    Peth, Stephan; Wittig, Marlen C.; Uteau Puschmann, Daniel; Pagenkemper, Sebastian; Haas, Christoph; Holthusen, Dörthe; Horn, Rainer

    2015-04-01

    Biopores are assumed to be an important factor for nutrient acquisition by providing biologically highly active soil-root interfaces to re-colonizing roots and controlling oxygen and water flows at the pedon scale and within the rhizosphere through the formation of branching channel networks which potentially enhance microbial turnover processes. Characteristic differences in pore morphologies are to be expected depending on the genesis of biopores which, for example, can be earthworm-induced or root-induced or subsequently modified by one of the two. Our understanding of biophysical interactions between plants and soil can be significantly improved by quantifying 3D biopore architectures across scales ranging from single biopores to pedon scale pore networks and linking pore morphologies to microscale measurements of transport processes (e.g. oxygen diffusion). While a few studies in the past have investigated biopore networks on a larger scale yet little is known on the micro-morphology of root-induces biopores and their associated rhizosphere. Also little data is available on lateral transport of oxygen through the rhizosphere which will strongly influence microbial turnover processes and consequently control the release and uptake of nutrients. This paper highlights results gathered within a research unit on nutrient acquisition from the subsoil. Here we focus on X-ray microtomography (XRCT) studies ranging from large soil columns (70 cm length and 20 cm diameter) to individual biopores and its surrounding rhizosphere. Samples were collected from sites with different preceding crops (fescue, chicory, alfalfa) and various cropping durations (1-3 years). We will present an approach for quantitative image analysis combined with micro-sensor measurements of oxygen diffusion and spatial gradients of O2 partial pressures to relate pore structure with transport functions. Implications of various biopore architectures for the accessibility of nutrient resources in

  15. Reading the primary structure of a protein with 0.07 nm3 resolution using a subnanometre-diameter pore

    Science.gov (United States)

    Kennedy, Eamonn; Dong, Zhuxin; Tennant, Clare; Timp, Gregory

    2016-11-01

    The primary structure of a protein consists of a sequence of amino acids and is a key factor in determining how a protein folds and functions. However, conventional methods for sequencing proteins, such as mass spectrometry and Edman degradation, suffer from short reads and lack sensitivity, so alternative approaches are sought. Here, we show that a subnanometre-diameter pore, sputtered through a thin silicon nitride membrane, can be used to detect the primary structure of a denatured protein molecule. When a denatured protein immersed in electrolyte is driven through the pore by an electric field, measurements of a blockade in the current reveal nearly regular fluctuations, the number of which coincides with the number of residues in the protein. Furthermore, the amplitudes of the fluctuations are highly correlated with the volumes that are occluded by quadromers (four residues) in the primary structure. Each fluctuation, therefore, represents a read of a quadromer. Scrutiny of the fluctuations reveals that the subnanometre pore is sensitive enough to read the occluded volume that is related to post-translational modifications of a single residue, measuring volume differences of ∼0.07 nm3, but it is not sensitive enough to discriminate between the volumes of all twenty amino acids.

  16. Soil hydraulic properties and REV study using X-ray microtomography and pore-scale modelling: saturated hydraulic conductivity

    Science.gov (United States)

    Gerke, Kirill; Khirevich, Siarhei; Sizonenko, Timofey; Karsanina, Marina; Umarova, Aminat; Korost, Dmitry; Matthai, Stephan; Mallants, Dirk

    2016-04-01

    To verify pore-scale modelling approach for determination of soil saturated hydraulic conductivity properties we scanned three cylindrical soil samples taken from A, Ah and B horizons using X-ray microtomography method. Resulting 3D soil images with resolutions of 15.25-20.96 μm were segmented into pores and solids and their maximum inscribed cube subvolumes were used as input data for three major pore-scale modelling methods to simulate saturated flow - lattice-Boltzmann method, finite-difference solution of the Stokes problem, and pore-network model. Provided that imaging resolution is high enough to capture the backbone of effective porosity and the main conducting pores all three methods resulted in simulated soil permeabilities close to experimental values for Ah and B samples. The resolution of A sample was not enough for an accurate modelling and we concluded that this soil requires multi-scale imaging to cover all relevant heterogeneities. We demonstrate that popular SWV method to choose segmentation threshold resulted in oversegmentation and order of magnitude higher permeability values. Careful manual thresholding combined with local segmentation algorithm provided much more accurate results. Detailed analysis of water retention curves showed that air-filled porosity at relevant pressure stages cannot be used for verification of the segmentation results. Representativity analysis by simulating flow in increasing soil volume up to 2.8 cm3 revealed no representative elementary volume (REV) within Ah sample and non-uniqueness of REV for B sample. The latter was explained by soil structure non-stationarity. We further speculate that structures soil horizons can exhibit no REV at all. We discuss numerous advantages of coupled imaging and pore-scale modelling approach and show how it can become a successor of the conventional soil coring method to parametrize large scale continuum models.

  17. Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete.

    Science.gov (United States)

    Liu, Jun; Qiu, Qiwen; Xing, Feng; Pan, Dong

    2014-05-30

    This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP) test and the scanning electron microscopy (SEM) images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days.

  18. Mutagenesis and functional analysis of the pore-forming toxin HALT-1 from Hydra magnipapillata.

    Science.gov (United States)

    Liew, Yvonne Jing Mei; Soh, Wai Tuck; Jiemy, William Febry; Hwang, Jung Shan

    2015-02-03

    Actinoporins are small 18.5 kDa pore-forming toxins. A family of six actinoporin genes has been identified in the genome of Hydra magnipapillata, and HALT-1 (Hydra actinoporin-like toxin-1) has been shown to have haemolytic activity. In this study, we have used site-directed mutagenesis to investigate the role of amino acids in the pore-forming N-terminal region and the conserved aromatic cluster required for cell membrane binding. A total of 10 mutants of HALT-1 were constructed and tested for their haemolytic and cytolytic activity on human erythrocytes and HeLa cells, respectively. Insertion of 1-4 negatively charged residues in the N-terminal region of HALT-1 strongly reduced haemolytic and cytolytic activity, suggesting that the length or charge of the N-terminal region is critical for pore-forming activity. Moreover, substitution of amino acids in the conserved aromatic cluster reduced haemolytic and cytolytic activity by more than 80%, suggesting that these aromatic amino acids are important for attachment to the lipid membrane as shown for other actinoporins. The results suggest that HALT-1 and other actinoporins share similar mechanisms of pore formation and that it is critical for HALT-1 to maintain an amphipathic helix at the N-terminus and an aromatic amino acid-rich segment at the site of membrane binding.

  19. Mutagenesis and Functional Analysis of the Pore-Forming Toxin HALT-1 from Hydra magnipapillata

    Directory of Open Access Journals (Sweden)

    Yvonne Jing Mei Liew

    2015-02-01

    Full Text Available Actinoporins are small 18.5 kDa pore-forming toxins. A family of six actinoporin genes has been identified in the genome of Hydra magnipapillata, and HALT-1 (Hydra actinoporin-like toxin-1 has been shown to have haemolytic activity. In this study, we have used site-directed mutagenesis to investigate the role of amino acids in the pore-forming N-terminal region and the conserved aromatic cluster required for cell membrane binding. A total of 10 mutants of HALT-1 were constructed and tested for their haemolytic and cytolytic activity on human erythrocytes and HeLa cells, respectively. Insertion of 1–4 negatively charged residues in the N-terminal region of HALT-1 strongly reduced haemolytic and cytolytic activity, suggesting that the length or charge of the N-terminal region is critical for pore-forming activity. Moreover, substitution of amino acids in the conserved aromatic cluster reduced haemolytic and cytolytic activity by more than 80%, suggesting that these aromatic amino acids are important for attachment to the lipid membrane as shown for other actinoporins. The results suggest that HALT-1 and other actinoporins share similar mechanisms of pore formation and that it is critical for HALT-1 to maintain an amphipathic helix at the N-terminus and an aromatic amino acid-rich segment at the site of membrane binding.

  20. Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2014-05-01

    Full Text Available This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride transport, apparent water permeability and pore structure. The results demonstrate that incorporation of fly ash, for the early test period, promotes the chloride ingress at the surface layer of concrete but substituting proportions of fly ash may have little impact on it. With the process of chloride immersion, the chloride concentration at the surface layer of concrete with or without fly ash was found to be nearly the same. In addition, it is suggested that the water permeability at the concrete surface area is closely related to the fly ash contents as well as the chloride exposure time. Pore structure was characterized by means of mercury intrusion porosimetry (MIP test and the scanning electron microscopy (SEM images. The modification of pore structure of concrete submersed in distilled water is determined by the pozzolanic reaction of fly ash and the calcium leaching effect. The pozzolanic reaction was more dominant at the immersion time of 180 days while the calcium leaching effect became more evident after 270 days.

  1. Horizontal flow fields observed in Hinode G-band images IV. Statistical properties of the dynamical environment around pores

    CERN Document Server

    Verma, Meetu

    2014-01-01

    The extensive database of high-resolution G-band images observed with the Hinode/SOT is a unique resource to derive statistical properties of pores using advanced digital image processing techniques. The study is based on two data sets: (1) Photometric and morphological properties inferred from single G-band images cover almost seven years from 2006 October 25 to 2013 August 31. (2) Horizontal flow fields have been derived from 356 one-hour sequences of G-band images using LCT for a shorter period of time from 2006 November 3 to 2008 January 6 comprising 13 active regions. A total of 7643/2863 (single/time-averaged) pores builds the foundation of the statistical analysis. Pores are preferentially observed at low latitudes in the southern hemisphere during the deep minimum of solar cycle No. 23. This imbalance reverses during the rise of cycle No. 24, when the pores migrate from high to low latitudes. Pores are rarely encountered in quiet-Sun G-band images, and only about 10% of pores exists in isolation. In g...

  2. Optimization of pore structure and particle morphology of mesoporous silica for antibody adsorption for use in affinity chromatography

    Science.gov (United States)

    Hikosaka, Ryouichi; Nagata, Fukue; Tomita, Masahiro; Kato, Katsuya

    2016-10-01

    Antibodies have received significant attention for use as antibody drugs, because they bind the objective protein (antigen) via antigen-antibody reactions. Recently, many reports have appeared on various monoclonal antibodies that recognize a single antigen. In this study, monoclonal antibodies are used as adsorbates on mesoporous silica (MPS) for affinity chromatography. MPS has high surface area and large pore volume; moreover, pore diameter, pore structure, and particle morphology are relatively easy to tune by adjusting the conditions of synthesis. The pore structure (two-dimensional (2D) hexagonal and three-dimensional cubic) and particle morphology (spherical and polyhedral) of MPS are optimized for use in a monoclonal antibody/MPS composite. When anti-IgG (one of the monoclonal antibodies) adsorbs on the MPS material and IgG (antigen) binds to anti-IgG/MPS composites, MCM-41p with a 2D-hexagonal pore structure and polyhedral particle morphology has the highest IgG binding efficiency. In addition, the antibody/MPS composites remain stable in chaotropic and low-pH solutions and can be cycled at least five times without decreasing IgG elution. In purification and removal tests, the use of the antibody/MPS composites allows only the objective protein from protein mixtures to be bound and eluted.

  3. Influences of composition of starting powders and sintering temperature on the pore size distribution of porous corundum-mullite ceramics

    Directory of Open Access Journals (Sweden)

    Shujing Li

    2005-01-01

    Full Text Available Porous corundum-mullite ceramics were prepared by an in-situ decomposition pore-forming technique. Starting powders were mixtures of milled Al(OH3 and microsilica and were formed into oblong samples with a length of 100mm and a square cross-section with edge size of 20mm. The samples were heated at 1300°C, 1400°C, 1500°C or 1600°C for 3h in air atmosphere, respectively. Apparent porosity was detected by Archimedes’ Principle with water as a medium. Pore size distribution and the volume percentage of micropores were measured by mercury intrusion porosimetry. The results show that the pore morphology parameters in the samples depend on four factors: particle size distribution of starting powders, decomposition of Al(OH3, the expansion caused by mullite and sintering. The optimum mode which has a higher apparent porosity up to 42.3%, well-distributed pores and more microsize pores up to 16.3% is sample No.3 and the most apposite sintering temperature of this sample is 1500°C.

  4. Reversible Self-Actuated Thermo-Responsive Pore Membrane

    Science.gov (United States)

    Park, Younggeun; Gutierrez, Maria Paz; Lee, Luke P.

    2016-12-01

    Smart membranes, which can selectively control the transfer of light, air, humidity and temperature, are important to achieve indoor climate regulation. Even though reversible self-actuation of smart membranes is desirable in large-scale, reversible self-regulation remains challenging. Specifically, reversible 100% opening/closing of pore actuation showing accurate responsiveness, reproducibility and structural flexibility, including uniform structure assembly, is currently very difficult. Here, we report a reversible, thermo-responsive self-activated pore membrane that achieves opening and closing of pores. The reversible, self-actuated thermo-responsive pore membrane was fabricated with hybrid materials of poly (N-isopropylacrylamide), (PNIPAM) within polytetrafluoroethylene (PTFE) to form a multi-dimensional pore array. Using Multiphysics simulation of heat transfer and structural mechanics based on finite element analysis, we demonstrated that pore opening and closing dynamics can be self-activated at environmentally relevant temperatures. Temperature cycle characterizations of the pore structure revealed 100% opening ratio at T = 40 °C and 0% opening ratio at T = 20 °C. The flexibility of the membrane showed an accurate temperature-responsive function at a maximum bending angle of 45°. Addressing the importance of self-regulation, this reversible self-actuated thermo-responsive pore membrane will advance the development of future large-scale smart membranes needed for sustainable indoor climate control.

  5. Hydrodemetallization of residue (Part 3). Influence of catalyst pore size

    Energy Technology Data Exchange (ETDEWEB)

    Hinuma, Yutaka; Kushiyama, Akira; Kobayashi, Satoru; Aizawa, Reiji; Inoue, Keiichi; Shimizu, Yoshikazu (National Research Inst. for Pollution and Resources, Tsukuba (Japan))

    1989-03-25

    Influence of catalyst pore size on hydrodemetallization of residues was studied, Starting oils were Khafji atmospheric residue and Morichal crude and two catalysts of alumina which have 93A and 160A mean pore diameters respectively and Mo was supported, were used. The rate at which asphaltene(A) was decomposed to maltene(M), related large to the demetallization of whole heavy oil and larger the pore diameter of catalyst, higher the demetallizing activity. But in the demetallization from A and M, the influence of pore size was different and vanadium(V) removal from A was preferable for larger pore size but was reverse from M. These were caused by the difference of diffusion in their pores. Ni was more difficult to remove than V. Catalyst of small pore size was preferable for simultaneous desulfurization, because sulfur compounds were composed of smaller molecular weight distribution. The decomposition of A started preferentially from part having large number of peripheral carbon in condensed aromatic ring or f{sub a} (aromaticity) and the catalyst of large pore size affected large on the structural change of A. 12 ref., 7 figs., 5 tabs.

  6. The Pore Structure of Direct Methanol Fuel Cell Electrodes

    DEFF Research Database (Denmark)

    Lund, Peter Brilner

    2005-01-01

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

  7. Reversible Self-Actuated Thermo-Responsive Pore Membrane.

    Science.gov (United States)

    Park, Younggeun; Gutierrez, Maria Paz; Lee, Luke P

    2016-12-19

    Smart membranes, which can selectively control the transfer of light, air, humidity and temperature, are important to achieve indoor climate regulation. Even though reversible self-actuation of smart membranes is desirable in large-scale, reversible self-regulation remains challenging. Specifically, reversible 100% opening/closing of pore actuation showing accurate responsiveness, reproducibility and structural flexibility, including uniform structure assembly, is currently very difficult. Here, we report a reversible, thermo-responsive self-activated pore membrane that achieves opening and closing of pores. The reversible, self-actuated thermo-responsive pore membrane was fabricated with hybrid materials of poly (N-isopropylacrylamide), (PNIPAM) within polytetrafluoroethylene (PTFE) to form a multi-dimensional pore array. Using Multiphysics simulation of heat transfer and structural mechanics based on finite element analysis, we demonstrated that pore opening and closing dynamics can be self-activated at environmentally relevant temperatures. Temperature cycle characterizations of the pore structure revealed 100% opening ratio at T = 40 °C and 0% opening ratio at T = 20 °C. The flexibility of the membrane showed an accurate temperature-responsive function at a maximum bending angle of 45°. Addressing the importance of self-regulation, this reversible self-actuated thermo-responsive pore membrane will advance the development of future large-scale smart membranes needed for sustainable indoor climate control.

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

    DEFF Research Database (Denmark)

    2008-01-01

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

  9. Bacteriocins : mechanism of membrane insertion and pore formation

    NARCIS (Netherlands)

    Moll, Gert N.; Konings, Wil N.; Driessen, Arnold J.M.

    1999-01-01

    Lactic acid bacteria produce several types of pore forming peptides. Class I bacteriocins are lantibiotics that contain (methyl)lanthionine residues that may form intramolecular thioether rings. These peptides generally have a broad spectrum of activity and form unstable pores. Class II bacteriocins

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  11. Bacteriocins : mechanism of membrane insertion and pore formation

    NARCIS (Netherlands)

    Moll, G.N.; Konings, W.N; Driessen, A.J.M.

    1999-01-01

    Lactic acid bacteria produce several types of pore forming peptides. Class I bacteriocins are lantibiotics that contain (methyl)lanthionine residues that may form intramolecular thioether rings. These peptides generally have a broad spectrum of activity and form unstable pores. Class II bacteriocins

  12. Letter to the editor: Diffusion under pore saturation conditions

    NARCIS (Netherlands)

    Krishna, R.; van Baten, J.M.

    2010-01-01

    In the article "Diffusion Under Pore Saturaton Conditions", Lettat et al. (1) presents a model to describe mixture diffusion in MFI zeolite under conditions of pore saturation. As a motivation for developing their model they remark ‘‘the classical adsorbed-phase diffusion models based on the Maxwell

  13. Volume of an Industrial Autoclave

    Directory of Open Access Journals (Sweden)

    Nicholas Madaffari

    2010-01-01

    Full Text Available We were able to determine the volume of an industrial autoclave sterilization tank using a technique learned in calculus. By measuring the dimensions of the tank and roughly estimating the equation of curvature at the ends of the tank, we were able to revolve half of the end of the tank around the x axis to get its fluid volume. Adding the two volumes of the ends and the volume of the cylindrical portion on the tank yielded the total volume.

  14. Characteristics of the development of pore stucture during carbonization of crushed and gradulated lean coal

    Energy Technology Data Exchange (ETDEWEB)

    Romanov, Yu.A.; Limonov, N.V.; Ivakhnyuk, G.K.

    1992-06-20

    The development of the pore structure of crushed and granulated lean coal during carbonization was investigated from the results of a study of the change of weight and volume of the coal pieces. It was shown that the macropore structure of the coal is formed in the low-temperature stage of carbonization and is due to the process of the removal of binder from the granules (620 K) and to destruction and elimination of volatile products from the crushed material (770 K). 9 refs., 2 figs., 3 tabs.

  15. Porous Boron Nitride with Tunable Pore Size.

    Science.gov (United States)

    Dai, Jun; Wu, Xiaojun; Yang, Jinlong; Zeng, Xiao Cheng

    2014-01-16

    On the basis of a global structural search and first-principles calculations, we predict two types of porous boron-nitride (BN) networks that can be built up with zigzag BN nanoribbons (BNNRs). The BNNRs are either directly connected with puckered B (N) atoms at the edge (type I) or connected with sp(3)-bonded BN chains (type II). Besides mechanical stability, these materials are predicted to be thermally stable at 1000 K. The porous BN materials entail large surface areas, ranging from 2800 to 4800 m(2)/g. In particular, type-II BN material with relatively large pores is highly favorable for hydrogen storage because the computed hydrogen adsorption energy (-0.18 eV) is very close to the optimal adsorption energy (-0.15 eV) suggested for reversible hydrogen storage at room temperature. Moreover, the type-II materials are semiconductors with width-dependent direct bandgaps, rendering the type-II BN materials promising not only for hydrogen storage but also for optoelectronic and photonic applications.

  16. Freezing of charged colloids in slit pores.

    Science.gov (United States)

    Grandner, Stefan; Klapp, Sabine H L

    2008-12-28

    Using Monte Carlo simulations in the grand canonical and isobaric ensembles we investigate freezing phenomena in a charged colloidal suspension confined to narrow slit pores. Our model involves only the macroions which interact via a Derjaguin-Landau-Verwey-Overbeek (DLVO) potential supplemented by a soft-sphere potential. We focus on DLVO parameters typical for moderately charged silica particles (with charges Z approximately 35) in solvents of low ionic strengths. The corresponding DLVO interactions are too weak to drive a (bulk) freezing transition. Nevertheless, for sufficiently small surface separations L(z) the confined systems display not only layering but also significant in-plane crystalline order at chemical potentials where the bulk system is a globally stable fluid (capillary freezing). At confinement conditions related to two-layer systems the observed in-plane structures are consistent with those detected in ground state calculations for perfect Yukawa bilayers [R. Messina and H. Lowen, Phys. Rev. Lett. 91, 146101 (2003)]. Here we additionally observe (at fixed L(z)) a compression-induced first-order phase transition from a two-layer to a three-layer system with different in-plane structure, in agreement with previous findings for pure hard spheres.

  17. Silicon pore optics developments and status

    Science.gov (United States)

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

    2012-09-01

    Silicon Pore Optics (SPO) is a lightweight high performance X-ray optics technology being developed in Europe, driven by applications in observatory class high energy astrophysics missions. An example of such application is the former ESA science mission candidate ATHENA (Advanced Telescope for High Energy Astrophysics), which uses the SPO technology for its two telescopes, in order to provide an effective area exceeding 1 m2 at 1 keV, and 0.5 m2 at 6 keV, featuring an angular resolution of 10” or better [1 to 24]. This paper reports on the development activities led by ESA, and the status of the SPO technology. The technology development programme has succeeded in maturing the SPO further and achieving important milestones, in each of the main activity streams: environmental compatibility, industrial production and optical performance. In order to accurately characterise the increasing performance of this innovative optical technology, the associated X-ray test facilities and beam-lines have been refined and upgraded.

  18. Evaluating transport in irregular pore networks

    Science.gov (United States)

    Klimenko, Dimitri A.; Hooman, Kamel; Klimenko, Alexander Y.

    2012-07-01

    A general approach for investigating transport phenomena in porous media is presented. This approach has the capacity to represent various kinds of irregularity in porous media without the need for excessive detail or computational effort. The overall method combines a generalized effective medium approximation (EMA) with a macroscopic continuum model in order to derive a transport equation with explicit analytical expressions for the transport coefficients. The proposed form of the EMA is an anisotropic and heterogeneous extension of Kirkpatrick's EMA [Rev. Mod. Phys.RMPHAT0034-686110.1103/RevModPhys.45.574 45, 574 (1973)] which allows the overall model to account for microscopic alterations in connectivity (with the locations of the pores and the orientation and length of the throat) as well as macroscopic variations in transport properties. A comparison to numerical results for randomly generated networks with different properties is given, indicating the potential for this methodology to handle cases that would pose significant difficulties to many other analytical models.

  19. Halogens in pore water of peat bogs – the role of peat decomposition and dissolved organic matter

    Directory of Open Access Journals (Sweden)

    H. Biester

    2006-01-01

    Full Text Available Halogens are strongly enriched in peat and peatlands and such they are one of their largest active terrestrial reservoir. The enrichment of halogens in peat is mainly attributed to the formation of organohalogens and climatically controlled humification processes. However, little is known about release of halogens from the peat substrate and the distribution of halogens in the peat pore water. In this study we have investigated the distribution of chlorine, bromine and iodine in pore water of three pristine peat bogs located in the Magellanic Moorlands, southern Chile. Peat pore waters were collected using a sipping technique, which allows in situ sampling down to a depth greater than 6m. Halogens and halogen species in pore water were determined by ion-chromatography (IC (chlorine and IC-ICP-MS (bromine and iodine. Results show that halogen concentrations in pore water are 15–30 times higher than in rainwater. Mean concentrations of chlorine, bromine and iodine in pore water were 7–15 mg l−1, 56–123 μg l−1, and 10–20 μg l−1, which correspond to mean proportions of 10–15%, 1–2.3% and 0.5–2.2% of total concentrations in peat, respectively. Organobromine and organoiodine were the predominant species in pore waters, whereas chlorine in pore water was mostly chloride. Advection and diffusion of halogens were found to be generally low and halogen concentrations appear to reflect release from the peat substrate. Release of bromine and iodine from peat depend on the degree of peat degradation, whereas this relationship is weak for chlorine. Relatively higher release of bromine and iodine was observed in less degraded peat sections, where the release of dissolved organic carbon (DOC was also the most intensive. It has been concluded that the release of halogenated dissolved organic matter (DOM is the predominant mechanism of iodine and bromine release from peat.

  20. Lateral line pore diameters correlate with the development of gas bubble trauma signs in several Columbia River fishes

    Science.gov (United States)

    Morris, R.G.; Beeman, J.W.; VanderKooi, S.P.; Maule, A.G.

    2003-01-01

    Gas bubble trauma (GBT) caused by gas supersaturation of river water continues to be a problem in the Columbia River Basin. A common indicator of GBT is the percent of the lateral line occluded with gas bubbles; however, this effect has never been examined in relation to lateral line morphology. The effects of 115, 125 and 130% total dissolved gas levels were evaluated on five fish species common to the upper Columbia River. Trunk lateral line pore diameters differed significantly (Psucker>largescale sucker>northern pikeminnow???chinook salmon???redside shiner). At all supersaturation levels evaluated, percent of lateral line occlusion exhibited an inverse correlation to pore size but was not generally related to total dissolved gas level or time of exposure. This study suggests that the differences in lateral line pore diameters between species should be considered when using lateral line occlusion as an indicator of gas bubble trauma. ?? 2003 Elsevier Science Inc. All rights reserved.

  1. Influence of pore structure on compressive strength of cement mortar.

    Science.gov (United States)

    Zhao, Haitao; Xiao, Qi; Huang, Donghui; Zhang, Shiping

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure.

  2. Vapor intrusion in soils with multimodal pore-size distribution

    Directory of Open Access Journals (Sweden)

    Alfaro Soto Miguel

    2016-01-01

    Full Text Available The Johnson and Ettinger [1] model and its extensions are at this time the most widely used algorithms for estimating subsurface vapor intrusion into buildings (API [2]. The functions which describe capillary pressure curves are utilized in quantitative analyses, although these are applicable for porous media with a unimodal or lognormal pore-size distribution. However, unaltered soils may have a heterogeneous pore distribution and consequently a multimodal pore-size distribution [3], which may be the result of specific granulometry or the formation of secondary porosity related to genetic processes. The present paper was designed to present the application of the Vapor Intrusion Model (SVI_Model to unsaturated soils with multimodal pore-size distribution. Simulations with data from the literature show that the use of a multimodal model in soils with such pore distribution characteristics could provide more reliable results for indoor air concentration, rather than conventional models.

  3. Role of pore-forming toxins in neonatal sepsis.

    Science.gov (United States)

    Sonnen, Andreas F-P; Henneke, Philipp

    2013-01-01

    Protein toxins are important virulence factors contributing to neonatal sepsis. The major pathogens of neonatal sepsis, group B Streptococci, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, secrete toxins of different molecular nature, which are key for defining the disease. Amongst these toxins are pore-forming exotoxins that are expressed as soluble monomers prior to engagement of the target cell membrane with subsequent formation of an aqueous membrane pore. Membrane pore formation is not only a means for immediate lysis of the targeted cell but also a general mechanism that contributes to penetration of epithelial barriers and evasion of the immune system, thus creating survival niches for the pathogens. Pore-forming toxins, however, can also contribute to the induction of inflammation and hence to the manifestation of sepsis. Clearly, pore-forming toxins are not the sole factors that drive sepsis progression, but they often act in concert with other bacterial effectors, especially in the initial stages of neonatal sepsis manifestation.

  4. Pore capillary pressure and saturation of methane hydrate bearing sediments

    Institute of Scientific and Technical Information of China (English)

    SUN Shicai; LIU Changling; YE Yuguang; LIU Yufeng

    2014-01-01

    To better understand the relationship between the pore capillary pressure and hydrate saturation in sedi-ments, a new method was proposed. First, the phase equilibria of methane hydrate in fine-grained silica sands were measured. As to the equilibrium data, the pore capillary pressure and saturation of methane hydrate were calculated. The results showed that the phase equilibria of methane hydrates in fine-grained silica sands changed due to the depressed activity of pore water caused by the surface group and negatively charged characteristic of silica particles as well as the capillary pressure in small pores together. The capil-lary pressure increased with the increase of methane hydrate saturation due to the decrease of the available pore space. However, the capillary-saturation relationship could not yet be described quantitatively because of the stochastic habit of hydrate growth.

  5. Biophysics, Pathophysiology and Pharmacology of Ion Channel Gating Pores

    Directory of Open Access Journals (Sweden)

    Adrien eMoreau

    2014-04-01

    Full Text Available Voltage sensor domain (VSDs are a feature of voltage gated ion channel (VGICs and voltage sensitive proteins. They are composed of four transmembrane (TM segments (S1 to S4. Currents leaking through VSDs are called omega or gating pore currents.Gating pores are caused by mutations of the highly conserved positively charged amino acids in the S4 segment that disrupt interactions between the S4 segment and the gating charge transfer center (GCTC. The GCTC separates the intracellular and extracellular water crevices. The disruption of S4–GCTC interactions allows these crevices to communicate and create a fast activating and non-inactivating alternative cation-selective permeation pathway of low conductance, or a gating pore.Gating pore currents have recently been shown to cause periodic paralysis phenotypes. There is also increasing evidence that gating pores are linked to several other familial diseases. For example, gating pores in Nav1.5 and Kv7.2 channels may underlie mixed arrhythmias associated with dilated cardiomyopathy (DCM phenotypes and peripheral nerve hyperexcitability (PNH respectively. There is little evidence for the existence of gating pore blockers. Moreover, it is known that a number of toxins bind to the VSD of a specific domain of Na+ channels. These toxins may thus modulate gating pore currents. This focus on the VSD motif opens up a new area of research centered on developing molecules to treat a number of cell excitability disorders such as epilepsy, cardiac arrhythmias, and pain.The purpose of the present review is to summarize existing knowledge of the pathophysiology, biophysics, and pharmacology of gating pore currents and to serve as a guide for future studies aimed at improving our understanding of gating pores and their pathophysiological roles.

  6. Effects of Mg content on pore structure and electrochemical corrosion behaviors of porous Al-Mg alloys

    Institute of Scientific and Technical Information of China (English)

    何文远; 肖逸锋; 吴靓; 许艳飞; 钱锦文; 贺跃辉; 郑学军

    2016-01-01

    Porous Al-Mg alloys with different nominal compositions were successfully fabricated via elemental powder reactive synthesis, and the phase composition, pore structure, and corrosion resistance were characterized with X-ray diffractometer, scanning electron microscope and electrochemical analyzer. The volume expansion ratio, open porosity and corrosion resistance in 3.5% (mass fraction) NaCl aqueous solution of the alloys increase at first and then decrease with the increase of Mg content. The maxima of volume expansion ratio and open porosity are 18.3% and 28.1% for the porous Al-56%Mg (mass fraction) alloy, while there is the best corrosion resistance for the porous Al-37.5% Mg (mass fraction) alloy. The pore formation mechanism can be explained by Kirkendall effect, and the corrosion resistance can be mainly affected by the phase composition for the porous Al-Mg alloys. They would be of the potential application for filtration in the chloride environment.

  7. Pore-Structure-Optimized CNT-Carbon Nanofibers from Starch for Rechargeable Lithium Batteries

    Directory of Open Access Journals (Sweden)

    Yongjin Jeong

    2016-12-01

    Full Text Available Porous carbon materials are used for many electrochemical applications due to their outstanding properties. However, research on controlling the pore structure and analyzing the carbon structures is still necessary to achieve enhanced electrochemical properties. In this study, mesoporous carbon nanotube (CNT-carbon nanofiber electrodes were developed by heat-treatment of electrospun starch with carbon nanotubes, and then applied as a binder-free electrochemical electrode for a lithium-ion battery. Using the unique lamellar structure of starch, mesoporous CNT-carbon nanofibers were prepared and their pore structures were controlled by manipulating the heat-treatment conditions. The activation process greatly increased the volume of micropores and mesopores of carbon nanofibers by etching carbons with CO2 gas, and the Brunauer-Emmett-Teller (BET specific area increased to about 982.4 m2·g−1. The activated CNT-carbon nanofibers exhibited a high specific capacity (743 mAh·g−1 and good cycle performance (510 mAh·g−1 after 30 cycles due to their larger specific surface area. This condition presents many adsorption sites of lithium ions, and higher electrical conductivity, compared with carbon nanofibers without CNT. The research suggests that by controlling the heat-treatment conditions and activation process, the pore structure of the carbon nanofibers made from starch could be tuned to provide the conditions needed for various applications.

  8. Induced polarization dependence on pore space geometry: Empirical observations and mechanistic predictions

    Science.gov (United States)

    Weller, A.; Slater, L. D.

    2015-12-01

    We use an extensive database to compare empirical observations and previously proposed empirical models against recently developed mechanistic formulations for the induced polarization (IP) response in porous media as a function of pore space geometry and interfacial chemistry. These comparisons support the argument that the pore-volume normalized internal surface (Spor) is the most important geometric parameter influencing the polarization. The specific polarizability derived from the empirical relationship between imaginary conductivity σ″ and Spor is independent of the porosity. By contrast, equivalent specific polarizability terms in recently proposed mechanistic models are found to be significantly correlated with porosity, and thus do not appear to represent an interfacial chemistry factor independent of the pore space geometry. Furthermore, the database shows no evidence for a significant decrease in the counterion mobility of clayey materials relative to clay-free materials, as postulated in recent studies. On the contrary, a single value of cp is consistent with no significant differences in ionic mobility given that all samples were saturated with a NaCl solution close to a common salinity of about 100 mS/m.

  9. Particle Size and Pore Structure Characterization of Silver Nanoparticles Prepared by Confined Arc Plasma

    Directory of Open Access Journals (Sweden)

    Mingru Zhou

    2009-01-01

    Full Text Available In the protecting inert gas, silver nanoparticles were successfully prepared by confined arc plasma method. The particle size, microstructure, and morphology of the particles by this process were characterized via X-ray powder diffraction (XRD, transmission electron microscopy (TEM and the corresponding selected area electron diffraction (SAED. The N2 absorption-desorption isotherms of the samples were measured by using the static volumetric absorption analyzer, the pore structure of the sample was calculated by Barrett-Joyner-Halenda (BJH academic model, and the specific surface area was calculated from Brunauer-Emmett-Teller (BET adsorption equation. The experiment results indicate that the crystal structure of the samples is face-centered cubic (FCC structure the same as the bulk materials, the particle size distribution ranging from 5 to 65 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results. The specific surface area is 23.81 m2/g, pore volumes are 0.09 cm3/g, and average pore diameter is 18.7 nm.

  10. Biotemplating pores with size and shape diversity for Li-oxygen Battery Cathodes

    Science.gov (United States)

    Oh, Dahyun; Ozgit-Akgun, Çagla; Akca, Esin; Thompson, Leslie E.; Tadesse, Loza F.; Kim, Ho-Cheol; Demirci, Gökhan; Miller, Robert D.; Maune, Hareem

    2017-01-01

    Synthetic porogens provide an easy way to create porous structures, but their usage is limited due to synthetic difficulties, process complexities and prohibitive costs. Here we investigate the use of bacteria, sustainable and naturally abundant materials, as a pore template. The bacteria require no chemical synthesis, come in variable sizes and shapes, degrade easier and are approximately a million times cheaper than conventional porogens. We fabricate free standing porous multiwalled carbon nanotube (MWCNT) films using cultured, harmless bacteria as porogens, and demonstrate substantial Li-oxygen battery performance improvement by porosity control. Pore volume as well as shape in the cathodes were easily tuned to improve oxygen evolution efficiency by 30% and double the full discharge capacity in repeated cycles compared to the compact MWCNT electrode films. The interconnected pores produced by the templates greatly improve the accessibility of reactants allowing the achievement of 4,942 W/kg (8,649 Wh/kg) at 2 A/ge (1.7 mA/cm2). PMID:28374862

  11. An undulation theory for condensation in open end slit pores: critical hysteresis temperature & critical hysteresis pore size.

    Science.gov (United States)

    Fan, Chunyan; Zeng, Yonghong; Do, D D; Nicholson, D

    2014-06-28

    A new theory of condensation in an open end slit pore, based on the concept of temperature dependent undulation, at the interface separating the adsorbed phase and the gas-like region, is presented. The theory, describes, for the first time, the microscopic origin of the critical hysteresis temperature and the critical hysteresis pore size, properties which are not accessible to any classical theories.

  12. Investigating Hydrophilic Pores in Model Lipid Bilayers Using Molecular Simulations: Correlating Bilayer Properties with Pore-Formation Thermodynamics.

    Science.gov (United States)

    Hu, Yuan; Sinha, Sudipta Kumar; Patel, Sandeep

    2015-06-23

    Cell-penetrating and antimicrobial peptides show a remarkable ability to translocate across physiological membranes. Along with factors such as electric-potential-induced perturbations of membrane structure and surface tension effects, experiments invoke porelike membrane configurations during the solute transfer process into vesicles and cells. The initiation and formation of pores are associated with a nontrivial free-energy cost, thus necessitating a consideration of the factors associated with pore formation and the attendant free energies. Because of experimental and modeling challenges related to the long time scales of the translocation process, we use umbrella sampling molecular dynamics simulations with a lipid-density-based order parameter to investigate membrane-pore-formation free energy employing Martini coarse-grained models. We investigate structure and thermodynamic features of the pore in 18 lipids spanning a range of headgroups, charge states, acyl chain lengths, and saturation. We probe the dependence of pore-formation barriers on the area per lipid, lipid bilayer thickness, and membrane bending rigidities in three different lipid classes. The pore-formation free energy in pure bilayers and peptide translocating scenarios are significantly coupled with bilayer thickness. Thicker bilayers require more reversible work to create pores. The pore-formation free energy is higher in peptide-lipid systems than in peptide-free lipid systems due to penalties to maintain the solvation of charged hydrophilic solutes within the membrane environment.

  13. Adsorption and Diffusion Properties of Ethylene, Benzene and Ethylbenzene in the Cylindrical Pore under Alkylation Reaction near Critical Regions by DCV-GCMD Simulation

    Institute of Scientific and Technical Information of China (English)

    刘涛; 刘洪来; 袁渭康

    2005-01-01

    A cylindrical pore model was used to represent approximately the pore of β-zeolite catalyst that had been used in the alkylation of benzene with ethylene and spherical Lennard-Jones molecules represented the components of the reaction system-ethylene, benzene and ethylbenzene. The dual control volume-grand canonical molecular dynamics (DCV-GCMD) method was used to simulate the adsorption and transport properties of three components under reaction in the cylindrical pore at 250℃ and 270℃ in the pressure range from 1 MPa to 8 MPa. The state map of the reactant mixture in the bulk phase could be divided into several different regions around its critical points. The simulated adsorption and transport properties in the pore were compared between the different near-critical regions. The thorough analysis suggested that the high pressure liquid region is the most suitable region for the alkylation reaction of benzene under the near-critical condition.

  14. Modeling pore corrosion in normally open gold- plated copper connectors.

    Energy Technology Data Exchange (ETDEWEB)

    Battaile, Corbett Chandler; Moffat, Harry K.; Sun, Amy Cha-Tien; Enos, David George; Serna, Lysle M.; Sorensen, Neil Robert

    2008-09-01

    The goal of this study is to model the electrical response of gold plated copper electrical contacts exposed to a mixed flowing gas stream consisting of air containing 10 ppb H{sub 2}S at 30 C and a relative humidity of 70%. This environment accelerates the attack normally observed in a light industrial environment (essentially a simplified version of the Battelle Class 2 environment). Corrosion rates were quantified by measuring the corrosion site density, size distribution, and the macroscopic electrical resistance of the aged surface as a function of exposure time. A pore corrosion numerical model was used to predict both the growth of copper sulfide corrosion product which blooms through defects in the gold layer and the resulting electrical contact resistance of the aged surface. Assumptions about the distribution of defects in the noble metal plating and the mechanism for how corrosion blooms affect electrical contact resistance were needed to complete the numerical model. Comparisons are made to the experimentally observed number density of corrosion sites, the size distribution of corrosion product blooms, and the cumulative probability distribution of the electrical contact resistance. Experimentally, the bloom site density increases as a function of time, whereas the bloom size distribution remains relatively independent of time. These two effects are included in the numerical model by adding a corrosion initiation probability proportional to the surface area along with a probability for bloom-growth extinction proportional to the corrosion product bloom volume. The cumulative probability distribution of electrical resistance becomes skewed as exposure time increases. While the electrical contact resistance increases as a function of time for a fraction of the bloom population, the median value remains relatively unchanged. In order to model this behavior, the resistance calculated for large blooms has been weighted more heavily.

  15. Pore Scale Dynamics of Microemulsion Formation.

    Science.gov (United States)

    Unsal, Evren; Broens, Marc; Armstrong, Ryan T

    2016-07-19

    Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod

    2013-07-13

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

  17. Impacts of pore- and petro-fabrics, mineral composition and diagenetic history on the bulk thermal conductivity of sandstones

    Science.gov (United States)

    Nabawy, Bassem S.; Géraud, Yves

    2016-03-01

    The present study aims to model the bulk thermal fabric of the highly porous (26.5 ≤ øHe ≤ 39.0%) siliceous Nubia sandstones in south Egypt, as well as their pore- and petro-anisotropy. The thermal fabric concept is used in the present study to describe the magnitude and direction of the thermal foliation 'F', lineation 'L' and anisotropy 'λ'. Cementation, pressure solution, compaction and the authigenic clay content are the main pore volume-controlling factors, whereas the cement dissolution and fracturing are the most important porosity-enhancing factors. The bulk thermal fabric of the Nubia sandstone is raised mostly from the contribution of the mineral composition and the pore volume. The kaolinite content and pore volume are the main reducing factors for the measured bulk thermal conductivity 'k', whereas the quartz content is the most important enhancing factors. The optical scanning technique, which is one of the most accurate and precise techniques, was applied for measuring the bulk thermal conductivity 'k' of the studied samples. For the dry state, the average thermal condutivity 'kav' in the NE-SW, NW-SE and vertical directions, varies from 1.53 to 2.40, 1.54 to 2.36 and from 1.31 to 2.20 W/(mK), respectively. On other hand, 'kav' for the saline water-saturated state for the NE-SW, NW-SE and vertical directions varies between 2.94 & 4.42, 2.90 & 4.31 and between 2.39 & 3.65 W/(mK), respectively. The present thermal pore fabric is slightly anisotropic, 'λ' varies from 1.10 to 1.41, refers mostly to the NW-SE direction (kmax direction, elongation direction), whereas the petro-fabric refers to NE-SW direction (kmax direction, elongation direction). This gives rise to a conclusion that the pore- and petro-fabrics have two different origins. Therefore, studying the thermal conductivity of the Nubia sandstone in 3-D indicates a pore fabric elongation fluctuating around the N-S direction.

  18. Impedance nanopore biosensor: influence of pore dimensions on biosensing performance.

    Science.gov (United States)

    Kant, Krishna; Yu, Jingxian; Priest, Craig; Shapter, Joe G; Losic, Dusan

    2014-03-07

    Knowledge about electrochemical and electrical properties of nanopore structures and the influence of pore dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different pore diameters (25-65 nm) and lengths (4-18 μm) were prepared and the internal pore surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of pore resistivity and conductivity were carried out for pores with different diameters and lengths. The results showed that smaller pore dimensions of 25 nm and pore lengths up to 10 μm provide better biosensing performance.

  19. Superplastically foaming method to make closed pores inclusive porous ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kishimoto, Akira; Hayashi, Hidetaka, E-mail: kishim-a@cc.okayama-u.ac.jp [Division of Molecular and Material Science, Graduate School of Natural Science and Technology, Okayama University Okayama (Japan)

    2011-04-15

    Porous ceramics incorporates pores to improve several properties including thermal insulation maintaining inherenet ceramic properties such as corrosion resistance and large mechanical strength. Conventional porous ceramics is usually fabricated through an insufficient sintering. Since the sintering accompanies the exclusion of pores, it must be terminated at the early stage to maintain the high porosity, leading to degraded strength and durability. Contrary to this, we have innovated superplastically foaming method to make ceramic foams only in the solid state. In this method, the previously inserted foam agent evaporates after the full densification of matrix at around the sintering temperature. Closed pores expand utilizing the superplastic deformation driven by the evolved gas pressure. The typical features of this superplastically foaming method are listed as follows, 1. The pores are introduced after sintering the solid polycrystal. 2. Only closed pores are introduced, improving the insulation of gas and sound in addition to heat. 3. The pore walls are fully densified expecting a large mechanical strength. 4. Compared with the melt foaming method, this method is practical because the fabrication temperature is far below the melting point and it does not need molds. 5. The size and the location pores can be controlled by the amount and position of the foam agent.

  20. Clostridial pore-forming toxins: powerful virulence factors.

    Science.gov (United States)

    Popoff, Michel R

    2014-12-01

    Pore formation is a common mechanism of action for many bacterial toxins. More than one third of clostridial toxins are pore-forming toxins (PFTs) belonging to the β-PFT class. They are secreted as soluble monomers rich in β-strands, which recognize a specific receptor on target cells and assemble in oligomers. Then, they undergo a conformational change leading to the formation of a β-barrel, which inserts into the lipid bilayer forming functional pore. According to their structure, clostridial β-PFTs are divided into several families. Clostridial cholesterol-dependent cytolysins form large pores, which disrupt the plasma membrane integrity. They are potent virulence factors mainly involved in myonecrosis. Clostridial heptameric β-PFTs (aerolysin family and staphylococcal α-hemolysin family) induce small pores which trigger signaling cascades leading to different cell responses according to the cell types and toxins. They are mainly responsible for intestinal diseases, like necrotic enteritis, or systemic diseases/toxic shock from intestinal origin. Clostridial intracellularly active toxins exploit pore formation through the endosomal membrane to translocate the enzymatic component or domain into the cytosol. Single chain protein toxins, like botulinum and tetanus neurotoxins, use hydrophobic α-helices to form pores, whereas clostridial binary toxins encompass binding components, which are structurally and functionally related to β-PFTs, but which have acquired the specific activity to internalize their corresponding enzymatic components. Structural analysis suggests that β-PFTs and binding components share a common evolutionary origin.

  1. Nuclear Pore-Like Structures in a Compartmentalized Bacterium

    Science.gov (United States)

    Sagulenko, Evgeny; Green, Kathryn; Yee, Benjamin; Morgan, Garry; Leis, Andrew; Lee, Kuo-Chang; Butler, Margaret K.; Chia, Nicholas; Pham, Uyen Thi Phuong; Lindgreen, Stinus; Catchpole, Ryan; Poole, Anthony M.; Fuerst, John A.

    2017-01-01

    Planctomycetes are distinguished from other Bacteria by compartmentalization of cells via internal membranes, interpretation of which has been subject to recent debate regarding potential relations to Gram-negative cell structure. In our interpretation of the available data, the planctomycete Gemmata obscuriglobus contains a nuclear body compartment, and thus possesses a type of cell organization with parallels to the eukaryote nucleus. Here we show that pore-like structures occur in internal membranes of G.obscuriglobus and that they have elements structurally similar to eukaryote nuclear pores, including a basket, ring-spoke structure, and eight-fold rotational symmetry. Bioinformatic analysis of proteomic data reveals that some of the G. obscuriglobus proteins associated with pore-containing membranes possess structural domains found in eukaryote nuclear pore complexes. Moreover, immunogold labelling demonstrates localization of one such protein, containing a β-propeller domain, specifically to the G. obscuriglobus pore-like structures. Finding bacterial pores within internal cell membranes and with structural similarities to eukaryote nuclear pore complexes raises the dual possibilities of either hitherto undetected homology or stunning evolutionary convergence. PMID:28146565

  2. Morphological Characterization of the Polyflux 210H Hemodialysis Filter Pores

    Directory of Open Access Journals (Sweden)

    A. Hedayat

    2012-01-01

    Full Text Available Background. Morphological characterization of hemodialysis membranes is necessary to improve pore design. Aim. To delineate membrane pore structure of a high flux filter, Polyflux 210H. Methods. We used a Joel JSM-6010LV scanning electron microscope (SEM and a SU6600 Hitachi field emission scanning electron microscope (FESEM to characterize the pore and fiber morphology. The maximal diameters of selected uremic toxins were calculated using the macromolecular modeling Crystallographic Object-Oriented Toolkit (COOT software. Results. The mean pore densities on the outermost and innermost surfaces of the membrane were 36.81% and 5.45%, respectively. The membrane exhibited a tortuous structure with poor connection between the inner and outer pores. The aperture’s width in the inner surface ranged between 34 and 45 nm, which is 8.76–11.60 times larger than the estimated maximum diameter of β2-microglobulin (3.88 nm. Conclusion. The results suggest that the diameter size of inner pore apertures is not a limiting factor to middle molecules clearance, the extremely diminished density is. Increasing inner pore density and improving channel structure are strategies to improve clearance of middle molecules.

  3. Novel Techniques to Characterize Pore Size of Porous Materials

    KAUST Repository

    Alabdulghani, Ali J.

    2016-04-24

    Porous materials are implemented in several industrial applications such as water desalination, gas separation and pharmaceutical care which they are mainly governed by the pore size and the PSD. Analyzing shale reservoirs are not excluded from these applications and numerous advantages can be gained by evaluating the PSD of a given shale reservoir. Because of the limitations of the conventional characterization techniques, novel methods for characterizing the PSD have to be proposed in order to obtain better characterization results for the porous materials, in general, and shale rocks in particular. Thus, permporosimetry and evapoporometry (EP) technologies were introduced, designed and utilized for evaluating the two key parameters, pore size and pore size distribution. The pore size and PSD profiles of different shale samples from Norway and Argentina were analyzed using these technologies and then confirmed by mercury intrusion porosimeter (MIP). Norway samples showed an average pore diameter of 12.94 nm and 19.22 nm with an average diameter of 13.77 nm and 23.23 nm for Argentina samples using permporosimetry and EP respectively. Both techniques are therefore indicative of the heterogeneity of the shales. The results from permporosimetry are in good agreement with those obtained from MIP technique, but EP for most part over-estimates the average pore size. The divergence of EP results compared to permporosimetry results is referred to the fact that the latter technique measures only the active pores which is not the case with the former technique. Overall, both techniques are complementary to each other which the results from both techniques seem reasonable and reliable and provide two simple techniques to estimate the pore size and pore size distributions for shale rocks.

  4. Modification of Aquifer Pore-Water by Static Diffusion Using Nano-Zero-Valent Metals

    Directory of Open Access Journals (Sweden)

    David D. J. Antia

    2011-01-01

    Full Text Available Sixteen static diffusion reactors containing n-ZVM (Fe0, Cu0, Al0 establish a common equilibrium redox (Eh-pH trajectory which is directly linked to the aquifer pore volume, volume of injected n-ZVM, throughflow rate within the aquifer and time. The effect of NaCl and Ca-montmorillonite on the trajectory is considered. The trajectory can be directly linked to TDS (EC and to the equilibrium removal of contaminants. In each example, the progressive oscillation between reduction and oxidation reactions (including Fenton reactions creates the catalytic nuclei (and redox environment required for the decomposition of organic pollutants and their reconstruction as simple alkanes and oxygenates.

  5. Characteristics of fluoride in pore-water at accidental hydrofluoric acid spillage site, Gumi, Korea

    Science.gov (United States)

    Kwon, E. H.; Lee, H. A.; Lee, J.; Kim, D.; Lee, S.; Yoon, H. O.

    2015-12-01

    A leakage accident of hydrofluoric acid (HF) occurred in Gumi, South Korea at Sep. 2012. The study site is located in the borderline between a large-scale industrial complex and a rural area. The HF plume was made immediately, and moved toward the rural area through air. After the accident, 212 ha of farm land were influenced and most of crops were withered. To recover the soil, CaO was applied after six months. Although several studies have done to estimate the extension and movement of HF plume in the air and to assess the impact on human health or plant after the incident, the long-term fate of fluoride (F) in the affected soils is not identified clearly. Thus, this study aimed to understand the behavior of F in the soil after HF releasing from accident site through chemical analysis and geochemical modeling. Within the radius of 1 km of accident site, 16 pore-water and soil samples were collected. The semi-quantitative soil composition (i.e., Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti), total F, total P, OM contents in soil, and soil pH have already been measured, and pore-water compositions are also identified. From these experimental and modeling data, we could be evaluate if impact of accident exists until now, and also could be select and identify existing form of fluoride in soil and pore-water.

  6. Simple model of capillary condensation in cylindrical pores

    Science.gov (United States)

    Szybisz, Leszek; Urrutia, Ignacio

    2002-11-01

    A simple model based on an approximation of the dropletlike model is formulated for studying adsorption of fluids into cylindrical pores. This model yields a nearly universal description of capillary condensation transitions for noble gases confined by alkali metals. The system's thermodynamical behavior is predicted from the values of two dimensionless parameters: D* (the reduced asymptotic strength of the fluid-adsorber interaction, a function of temperature) and R* (the reduced radius of the pore). The phenomenon of hysteresis inherently related to capillary condensation is discussed. The connection to a previously proposed universality for cylindrical pores is also established.

  7. Pore structure of SWNTs with high hydrogen storage capacity

    Institute of Scientific and Technical Information of China (English)

    杨全红; 刘畅; 刘敏; 樊彦贞; 成会明; 王茂章

    2002-01-01

    This paper reveals, by analyses of nitrogen cryo-adsorption isotherm, the energetic and structural heterogeneity of single-walled carbon nanotubes (SWNTs) which has a high hydrogen storage capacity. It was found that SWNTs had manifold pore structures and distributed surface energy. By comparison of the pore structures and energy distributions of SWNTs before and after hydrogen adsorption, it is preliminarily indicated that hydrogen adsorption occurred in micropores and mesopores with smaller diameter, and that the pores of different diameters determined different hydrogen adsorption processes and underwent different structure changes during hydrogen adsorption.

  8. NJP VOLUME 41 NO 2

    African Journals Online (AJOL)

    PROF. EZECHUKWU

    2013-11-24

    Nov 24, 2013 ... sleep. There was also increase in both frequency of uri- nation and volume of urine voided; from1- 2 times to ... phagia, fever, head trauma, chronic cough, weight loss, ... water deprivation at 15Kg. Total volume of urine voided.

  9. Distribución de poros en una ladera de pampa ondulada cultivada con siembre directa Pore distribution on a hillslope under direct sowing in the rolling Pampa region of Argentina

    Directory of Open Access Journals (Sweden)

    Mario Castiglioni

    2010-12-01

    Full Text Available Para seleccionar las opciones de manejo mas adecuadas en suelos erosionados, es imprescindible identificar primeramente que atributos edáficos son modificados a partir de dicho proceso de degradación. El objetivo del presente trabajo fue determinar el efecto del diferente grado de erosión hídrica en un Argiudol Vértico cultivado con siembra directa, sobre la distribución de poros a dos profundidades (0-5 cm y 5-10 cm. La toma de muestras se realizó sobre tres transectas paralelas siguiendo la dirección de la pendiente. En cada una de ellas y a intervalos de 8 m se determinó el volumen que ocuparon distintas clases por tamaño de poro, la porosidad total y la profundidad al horizonte argílico. También se cuantificó en distintos puntos del área de trabajo la textura de los dos estratos estudiados. Si bien en el área bajo estudio la profundidad al horizonte argílico fluctuó entre 32 y 19 cm y el contenido de arcilla tuvo variaciones del 22,6 (0-5 cm y 28,0% (5-10 cm, no se observaron diferencias significativas en el volumen ocupado por las distintas categorías de poro estudiadas entre suelos con distinto grado de erosión. Al realizar un reagrupamiento de las observaciones de acuerdo a su porosidad total, se evidenció en cada estrato que las situaciones con mayor porosidad total presentaron un mayor volumen (PIn order to select the most appropriate management techniques for eroded soils it is essential to first of all identify those soil attributes modified by this degradation process. The aim of this study was to determine the effect of different degrees of water erosion in a Vertic Argiudoll under direct sowing on the distribution of pores at two depths (0-5 cm and 5-10 cm. Sampling was carried out in three parallel transects in the slope direction. The volume occupied by different pore-size classes, total porosity and depth to the argilic horizon were measured at 8 m-intervals in each transect. Soil texture was also measured at

  10. Nano pores evolution in hydroxyapatite microsphere during spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Lin C.

    2011-01-01

    Full Text Available Micron-spherical granules of hydroxyapatite (HAp nanoparticles were prepared by powder granulation methods. Through subsequent sintering, porous HAp microspheres with tailored pore and grain framework structures were obtained. Detailed microstructure investigation by SEM and TEM revealed the correlation of the pore structure and the necking strength with the sintering profiles that determine the coalescence features of the nanoparticles. The partially sintered porous HAp microspheres containing more than 50% porosity consisting of pores and grains both in nano-scale are active in inducing the precipitation of HAp in simulated body fluid. The nano-porous HAp microspheres with an extensive surface and interconnecting pores thus demonstrate the potential of stimulating the formation of collagen and bone and the integration with the newly formed bones during physiological bone remodeling.

  11. Bilayer Deformation, Pores, and Micellation Induced by Oxidized Lipids.

    Science.gov (United States)

    Boonnoy, Phansiri; Jarerattanachat, Viwan; Karttunen, Mikko; Wong-Ekkabut, Jirasak

    2015-12-17

    The influence of different oxidized lipids on lipid bilayers was investigated with 16 individual 1 μs atomistic molecular dynamics (MD) simulations. Binary mixtures of lipid bilayers of 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (PLPC) and its peroxide and aldehyde products were performed at different concentrations. In addition, an asymmetrical short chain lipid, 1-palmitoyl-2-decanoyl-sn-glycero-3-phosphatidylcholine (PDPC), was used to compare the effects of polar/apolar groups in the lipid tail on lipid bilayer. Although water defects occurred with both aldehyde and peroxide lipids, full pore formation was observed only for aldehyde lipids. At medium concentrations the pores were stable. At higher concentrations, however, the pores became unstable and micellation occurred. Data analysis shows that aldehyde lipids' propensity for pore formation is due to their shorter and highly mobile tail. The highly polar peroxide lipids are stabilized by strong hydrogen bonds with interfacial water.

  12. The Pore Structure and Hydration Performance of Sulphoaluminate MDF Cement

    Institute of Scientific and Technical Information of China (English)

    HUANG Cong-yun; YUAN Run-zhang; LONG Shi-zong

    2004-01-01

    The hydration and pore structure of sulphoaluminate MDF cement were studied by X-ray diffractometer ( XRD ), scanning electron microscope (SEM) and mercury intrusion porosimeter ( MIP ) etc. The ex-perimental results indicate that hydration products of the materials are entringites ( Aft ), aluminium hydroxide andCSH (Ⅰ) gel etc. Due to its very low water-cement ratio, hydration function is only confined to the surfaces of ce-ment grains, and there is a lot of sulphoaluminate cement in the hardenite which is unhydrated yet. Hydration re-action was rapidly carried under the condition of the heat-pressing. Therefore cement hydrates Aft, CSH (Ⅰ) andaluminium hydroxide gel fill in pores. The expansibility of Aft makes the porosity of MDF cement lower ( less than1 percent ) and the size of pore smaller (80 percent pore was less than 250A), and enhances its strength.

  13. Diffusion Pore Imaging by Hyperpolarized Xenon-129 Nuclear Magnetic Resonance

    CERN Document Server

    Kuder, Tristan Anselm; Windschuh, Johannes; Laun, Frederik Bernd

    2012-01-01

    Nuclear magnetic resonance (NMR) diffusion measurements are widely used to derive parameters indirectly related to the microstructure of biological tissues and porous media. However, a direct imaging of cell or pore shapes and sizes would be of high interest. For a long time, determining pore shapes by NMR diffusion acquisitions seemed impossible, because the necessary phase information could not be preserved. Here we demonstrate experimentally using the measurement technique which we have recently proposed theoretically that the shape of arbitrary closed pores can be imaged by diffusion acquisitions, which yield the phase information. For this purpose, we use hyperpolarized xenon gas in well-defined geometries. The signal can be collected from the whole sample which mainly eliminates the problem of vanishing signal at increasing resolution of conventional NMR imaging. This could be used to non-invasively gain structural information inaccessible so far such as pore or cell shapes, cell density or axon integri...

  14. Formation of a quasi-solid structure by intercalated noble gas atoms in pores of Cu(I)-MFU-4l metal-organic framework.

    Science.gov (United States)

    Magdysyuk, Oxana V; Denysenko, Dmytro; Weinrauch, Ingrid; Volkmer, Dirk; Hirscher, Michael; Dinnebier, Robert E

    2015-01-14

    The primary adsorption sites for Kr and Xe within the large-pore metal-organic framework Cu(I)-MFU-4l have been investigated by high-resolution synchrotron powder diffraction, revealing an enormous number of adsorption sites: in total, 10 crystallographically different positions for Xe and 8 positions for Kr were localized, the first five of which are located near metal atoms and the organic linker, and the remaining sites form a second adsorption layer in the pores.

  15. Diffusion in the pore water of compacted crushed salt

    Energy Technology Data Exchange (ETDEWEB)

    Fluegge, Judith; Herr, Sebastian; Lauke, Thomas; Meleshyn, Artur; Miehe, Ruediger; Ruebel, Andre

    2016-07-15

    Diffusion of dissolved radionuclides in the pore water of compacted crushed salt in the long-term is the most relevant process for the release of radionuclides from a dedicated repository for high-level waste in a salt formation as has been shown in latest safety assessments and research projects /BUH 16/. So far, diffusion coefficients for free water have been applied for the diffusion in pore water in models for long-term safety assessments. This conservative assumption was used, because data on the diffusion coefficient of dissolved substances in crushed salt have been missing. Furthermore, the diffusion coefficient in the pore water was assumed to be constant and independent from the degree of compaction of the crushed salt. The work presented in this report was intended to contribute to fill this gap of knowledge about how the diffusion of radionuclides takes place in the compacted backfill of a repository in salt. For the first time, the pore diffusion coefficient as well as its dependence on the porosity of the crushed salt was determined experimentally by means of through-diffusion experiments using caesium as tracer. The results achieved in this project suggest that the diffusion in compacted crushed salt is not fully comparable to that in a homogeneous, temporally stable porous medium like sand or clay. The results obtained from four diffusion experiments show a remarkably different behaviour and all yield unique concentration versus time plots which includes highly temporal variable tracer fluxes with even full interruptions of the flux for longer periods of time. This effect cannot be explained by assuming a tracer transport by diffusion in a temporarily invariant pore space and / or under temporally invariant experimental conditions. From our point of view, a restructuring of the pore space seems to lead to closed areas of pore water in the sample which may open up again after some time, leading to a variable pore space and hence variable diffusive

  16. Molecular biology and biophysical properties of ion channel gating pores.

    Science.gov (United States)

    Moreau, Adrien; Gosselin-Badaroudine, Pascal; Chahine, Mohamed

    2014-11-01

    The voltage sensitive domain (VSD) is a pivotal structure of voltage-gated ion channels (VGICs) and plays an essential role in the generation of electrochemical signals by neurons, striated muscle cells, and endocrine cells. The VSD is not unique to VGICs. Recent studies have shown that a VSD regulates a phosphatase. Similarly, Hv1, a voltage-sensitive protein that lacks an apparent pore domain, is a self-contained voltage sensor that operates as an H⁺ channel. VSDs are formed by four transmembrane helices (S1-S4). The S4 helix is positively charged due to the presence of arginine and lysine residues. It is surrounded by two water crevices that extend into the membrane from both the extracellular and intracellular milieus. A hydrophobic septum disrupts communication between these water crevices thus preventing the permeation of ions. The septum is maintained by interactions between the charged residues of the S4 segment and the gating charge transfer center. Mutating the charged residue of the S4 segment allows the water crevices to communicate and generate gating pore or omega pore. Gating pore currents have been reported to underlie several neuronal and striated muscle channelopathies. Depending on which charged residue on the S4 segment is mutated, gating pores are permeant either at depolarized or hyperpolarized voltages. Gating pores are cation selective and seem to converge toward Eisenmann's first or second selectivity sequences. Most gating pores are blocked by guanidine derivatives as well as trivalent and quadrivalent cations. Gating pores can be used to study the movement of the voltage sensor and could serve as targets for novel small therapeutic molecules.

  17. Relationship between pore structure and compressive strength of concrete: Experiments and statistical modeling

    Indian Academy of Sciences (India)

    J BU; Z TIAN

    2016-03-01

    Properties of concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the pore structure-compressive strength relationship in concrete. Several concrete mixtures with different pore structures are proportioned and subjected to static compressive tests. The pore structure features such as porosity, pore size distribution are extracted using mercury intrusion porosimetry technique. A statistical model is developed to relate thecompressive strength to relevant pore structure features.

  18. A free software for pore-scale modelling: solving Stokes equation for velocity fields and permeability values in 3D pore geometries

    Science.gov (United States)

    Gerke, Kirill; Vasilyev, Roman; Khirevich, Siarhei; Karsanina, Marina; Collins, Daniel; Korost, Dmitry; Mallants, Dirk

    2015-04-01

    In this contribution we introduce a novel free software which solves the Stokes equation to obtain velocity fields for low Reynolds-number flows within externally generated 3D pore geometries. Provided with velocity fields, one can calculate permeability for known pressure gradient boundary conditions via Darcy's equation. Finite-difference schemes of 2nd and 4th order of accuracy are used together with an artificial compressibility method to iteratively converge to a steady-state solution of Stokes' equation. This numerical approach is much faster and less computationally demanding than the majority of open-source or commercial softwares employing other algorithms (finite elements/volumes, lattice Boltzmann, etc.) The software consists of two parts: 1) a pre and post-processing graphical interface, and 2) a solver. The latter is efficiently parallelized to use any number of available cores (the speedup on 16 threads was up to 10-12 depending on hardware). Due to parallelization and memory optimization our software can be used to obtain solutions for 300x300x300 voxels geometries on modern desktop PCs. The software was successfully verified by testing it against lattice Boltzmann simulations and analytical solutions. To illustrate the software's appl