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[en] Fabrication process of microporous filter supports of high permeability and more particularly tubular filter supports used to make porous barriers needed in isotope separation
[fr]Procede de fabrication de supports de filtres microporeux a permeabilite elevee et, en particulier, aux supports de filtres de forme tubulaire dont on se sert pour fabriquer des barrieres poreuses utilisees dans la separation de certains isotopes
[en] A series of in-situ permeation tests are being conducted to determine permeation coefficients and breakthrough and saturation times for certain elastomeric O-rings with various gases that might be used as leak test tracers. The work is directed towards developing more effective and efficient nuclear material shipping packaging leak test procedures. The tests are in progress presently, and a formal report will be published in 1984
[en] In this work, we model the biofilm growth at the microscale using a rectangular pore network model in 2D and a cubic network in 3D. For the 2D network, we study the effects of bioclogging on porosity and permeability when we change parameters like the number of nodes in the network, the network size, and the concentration of nutrients at the inlet. We use a 3D cubic network to study the influence of the number of nodes in the z direction on the biofilm growth and on upscalability. We show that the biofilm can grow uniformly or heterogeneously through the network. Using these results, we determine the conditions for upscalability of bioclogging for rectangular and cubic networks. If there is uniform biofilm growth, there is a unique relation between permeability and porosity, K ∼ ϕ2, this relation does not depend on the volume of the network, therefore the system is upscalable. However, if there is preferential biofilm growth, the porosity-permeability relation is not uniquely defined, hence upscalability is not possible. The Damköhler number is used to determine when upscalability is possible. If the Damköhler number is less than 101, the biofilm grows uniformly and therefore the system is upscalable. However, if the Damköhler number is greater than 103, the biofilm growth exhibits a deviation from uniform biofilm growth and heterogeneous growth is observed, therefore upscalability is not possible. There is a transition from uniform growth to preferential growth if the Damköhler number is between 101 and 103.
[en] Exposure to environmental pollutants results in out-of-balance of vascular homeostasis. Endothelial dysfunction leads to a disruption of the endothelial permeability characteristics, associated with cardiovascular diseases. We previously reported that endosulfan could cause endothelial dysfunction, but the role of endosulfan in permeability of endothelial cells has been unexplored. To elucidate molecular mechanism of endosulfan-induced changes in endothelial permeability, human umbilical vein endothelial cells (HUVECs) were exposed to endosulfan, followed by endothelial permeability analysis. The results showed that permeability of HUVECs was enhanced at 48 h after exposure to endosulfan in a dose-dependent manner. Immunofluorescence analysis demonstrated the disruptions of actin cytoskeleton and focal adhesion in endosulfan-exposed cells. Endosulfan activated MMP3/LAMC1/FAK signaling pathway, and downregulated ROCK and PXN in transcellular pathway. Endosulfan affected adherens junctions via E-cadherin and β-catenin, and impaired gap junctions through downregulation of Cx43 in paracellular pathway. We predicted four closely related human cardiovascular diseases in Nextbio, including shock, coronary arteriosclerosis, disorder of cardiac function and hypertensive disorder in relation to endosulfan exposure. Some genes such as ROCK2 and PXN were predicted to be key genes in these diseases. These findings suggest that endosulfan increased endothelial permeability by paracellular and transcellular pathways, implicating the potential correlation between endosulfan and cardiovascular diseases. - Highlights: • Endosulfan enhances endothelial permeability in HUVECs. • Endosulfan disrupts actin cytoskeleton and focal adhesion. • Endosulfan affects adherens junctions and impaired gap junctions. • Cardiovascular diseases are predicted to correlate with endosulfan exposure.
[en] The permeation rate of deuterium through high-purity beryllium membranes was measured using the gas-driven permeation technique. The time-dependent and the steady-state deuterium flux data were analyzed and the effective diffusivities of the samples were determined. A multilayer permeation theory was used in order to eliminate the surface oxide effects and the diffusion coefficients of the bulk beryllium were determined. The diffusion parameters obtained for the extra-grade beryllium samples (99.8%) are D0 = 6.7 x 10-9 [m2/s] and ED = 28.4 [KJ/mol]; and for the high-grade beryllium samples (99%) the parameters are D0 = 8.0 x 10-9 [m2/s] and ED = 35.1 [KJ/mol]
[en] By investigating wave properties at cloak boundaries, invisibility cloaks with arbitrary shape constructed by general coordinate transformations are confirmed to be perfectly invisible to the external incident wave. The differences between line transformed cloaks and point transformed cloaks are discussed. The fields in the cloak medium are found analytically to be related to the fields in the original space via coordinate transformation functions. At the exterior boundary of the cloak, it is shown that no reflection is excited even though the permittivity and permeability do not always have a perfectly matched layer form, whereas at the inner boundary, no reflection is excited either, and in particular no field can penetrate into the cloaked region. However, for the inner boundary of any line transformed cloak, the permittivity and permeability in a specific tangential direction are always required to be infinitely large. Furthermore, the field discontinuity at the inner boundary always exists; the surface current is induced to make this discontinuity self-consistent. A point transformed cloak does not experience such problems. The tangential fields at the inner boundary are all zero, implying that no field discontinuity exists
[en] The permeability of a fractures hard rock formation is usually calculated using the recorded overpressure and the rate of flow during a double packer test. Existing formulae assume that the formation is both homogeneous, and isotropic, and the borehole is sealed in the region outside the packers, but in practice these assumptions are not fulfilled. The objective of the present investigation is to check the influence on the calculated rock permeability of inhomogeneities, anisotropy and return of flow from the formation into the unsealed part of the borehole by numerical simulation of double packer tests. For this purpose different formations with known permeabilities were considered. (Authors)
[en] Hydrogen superpermeation through a very pure iron membrane exposed to H-atoms on its upstream side and the compression of the released H2-molecules on the downstream side have been investigated at various driving pressures (10-7≤p1≤10-3 mbar) and in the presence of helium. The compression runs have been extended to downstream pressures between 1 and 10 mbar corresponding to a maximum compression factor of 6x105. That is not the highest possible factor because the time slopes of the pressure increase in this range reveal no saturation tendency. The dependence on time of the pressure increase is nearly linear up to 10-1 mbar. Hydrogen throughput and pump speed have been evaluated from the initial pressure slopes. Helium inlet upstream to a partial pressure of 10-3 mbar has no distinguishable influence on the pressure slope. This observation has been confirmed by supplementary measurements of the hydrogen permeation flux at various compositions of the hydrogen/helium driving gas. (orig.)