Secondary Barrier Research Articles

Coupled uranium mineralisation and bacterial sulphate reduction for the genesis of the Baxingtu sandstone-hosted U deposit, SW Songliao Basin, NE China

The Baxingtu deposit is a typical redox front tabular-shaped uranium deposit hosted in sandstones of the Late Cretaceous Yaojia Formation deposited within a braided river environment during the post-rift stage of the Songliao Basin, in northeast China. This study proposes the first metallogenic model for the Baxingtu deposit and provides new data on genetic processes involved in the uranium mineralisation of sandstone-type deposits that were characterised through petrographic observations, whole-rock geochemistry, and geochemical and/or mineralogical study of iron disulphide, uranium minerals, Fe-Ti oxides (EPMA, LA-ICP-MS), and organic matter (REP). The δ34S value has been measured in situ by SIMS on the different generations of iron disulphide.Within regional primary reduced sandstones, pre-ore uranium enrichment (Umean=7.6ppm in whole rock) was identified on altered Fe-Ti oxides along with minor concentrations on organic matter (respectively 26.3% and 1.3% of the whole-rock U content), which together represent a significant source of uranium for the mineralisation. Additional pre-ore uranium concentrations may also be associated with clay minerals. Petrographic observations and REP data indicate that organic matter occurring in the host-sandstone is mainly inherited from land plants and corresponds to type III or type IV kerogens. Ore-stage iron disulphides largely occur as framboids and in replacement of organic matter or also as sub-idiomorphic to idiomorphic cement and crystal. Trace element signatures detected within framboids are likely indicative of formation mainly from a single event. Framboids and iron disulphide in replacement of organic matter have a light sulphur isotope signature characterised by δ34S values from −72.0 to −6.2‰, suggesting that sulphur originated from bacterial sulphate reduction, which was mainly responsible for (1) the liberation of U from Fe-Ti oxides and organic matter, (2) the generation of ore-stage iron disulphides, (3) the bioreduction of uranium and (4) the production of a secondary H2S-rich reducing barrier also involved in uranium reduction. Uranyl and sulphate ions were transported through the host sandstone by low-temperature oxygenated groundwater and U(IV) was precipitated at the redox interface as nano to microcrystals of pitchblende and coffinite, dominantly associated with bacterial substrate and as intergrowth with biogenic iron disulphide or directly associated with organic matter and residual Ti-Fe oxides. The uranium mineralisation does not replace ore-stage iron disulphides. Therefore, the combined mineralogical, geochemical, and isotopic characteristics of the Baxingtu tabular uranium deposit characterise dominantly biogenic processes for the genesis of the uranium mineralisation.

Rejection of trace pharmaceutically active compounds present in municipal wastewaters using ceramic fine ultrafiltration membranes: Effect of feed solution pH and fouling phenomena

Abstract This study investigates the influence of feed solution pH and fouling on the rejection of ten selected pharmaceutically active compounds (PhACs) with different physicochemical characteristics (molecular weight, water solubility, log KOW, pKa, dipole moment, etc.) by three multichannel ceramic ultrafiltration membranes, ranging from 1 to 8 kDa, in order to improve their removal from water. For this purpose, the comparison between filtration of PhACs in deionised water (Feed I) and in real wastewater effluent (Feed II) was performed, demonstrating that the variation of pH and the formation of a foulant layer altered the separation mechanism and hence the rejection values of each PhAC varied. Higher rejections of most of the PhACs were higher at slightly alkaline pH, especially for anionic compounds in the filtration with real wastewater. In these conditions, flux decline was more severe. The formed fouling layer onto the hydrophilic membrane surface acted as a secondary barrier for separation with different properties like hydrophobicity and charge. Electrostatic interactions were the main separation mechanism in the filtration of PhACs in deionised water, while the hydrophobic/hydrophilic interactions played a crucial role in the filtration experiments with real wastewater effluent. Thus, the reported results indicated that the rejection of pharmaceutically active compounds was strongly pH-dependent, except for hydrophilic neutral compounds (acetaminophen and caffeine), which showed a pH-independent behaviour with low rejection values.

Geological characterization of the Aquistore CO2 storage site from 3D seismic data

A 30km2 3D seismic survey was conducted in 2012 at the Aquistore CO2 storage site near Estevan, Saskatchewan, Canada. The purpose of the survey was to investigate the geological suitability of this site for the purposes of long-term CO2 storage. The resultant 3D seismic volume has been interpreted in conjunction with geological and geophysical logs from the 3400m deep CO2 injection well (01/5-6-2-8-W2M) that was subsequently drilled. The CO2 storage reservoir resides immediately above the Precambrian crystalline basement (3400m) and is part of a regionally extensive >200m-thick clastic interval (Winnipeg and Deadwood formations). The reservoir is capped by a 15m thick laterally-continuous shale unit (Icebox Member of the Winnipeg Formation). A regional evaporite at ∼2500m depth (Prairie Formation) provides a secondary barrier to vertical flow. It is >150m thick and shows no salt dissolution features. Above the Prairie Formation are 1500m of laterally continuous Middle Devonian to Lower Cretaceous strata and 1000m of Upper Cretaceous and younger sedimentary rocks, including additional regionally-extensive aquitards that provide tertiary seals: Watrous Formation (∼120m), Colorado Group (>185m), and Bearpaw Formation. There is no evidence of vertical faulting extending through the Devonian or deeper section. A local sub-vertical Precambrian basement fault is interpreted to exist. It lies beneath a flexure within the overlying Cambrian to Silurian strata. The fault is oriented at an azimuth of 75°–85° relative to the regional maximum horizontal stress making it less susceptible to reactivation during CO2 injection. There is no clear evidence that the strata in an overlying flexure are ruptured or faulted. Natural seismicity in the area is very low and the nearest known significant seismogenic fault zone is located ∼200km away.

Evaluation of chitosan hydrochloride-alginate as enteric micro-probiotic-carrier with dual protective barriers

In this study, the cells-free and cells-loaded chitosan hydrochloride-alginate (CHC-Alg) microcapsules were firstly fabricated with polyelectrolyte complexes via an orifice-polymerization method. Scanning electron microscope images showed that the CHC-Alg microcapsules had a typical shell-core structure and the model probiotic cells (Bacillus licheniformis) were embedded in the core in cells-loaded microcapsules. The microcapsules prepared had good thermal stability and moisture property (3.89%). Cells survival and release studies showed that the number of probiotic cells released from the cells-loaded microcapsules (approx. 6.36logCFUml−1) was 6.19logCFUml−1 when they were performed in the simulated gastric fluid (SGF, pH 2.0) for 1h and subsequently in the simulated intestinal fluid (SIF, 0.3%) for 4h. The CHC-Alg microcapsules with favorable swelling performances were helpful to permeate the harsh acid to protect the cells in the SGF (pH 2.0). The CHC-Alg microcapsules effectively protected the model probiotic cells, which was attributed to the “dual protective barriers” of the shell-core structure, that is, the primary barrier of the Alg hydrogel layer formed with a compact polymer matrix and the secondary barrier of the PEC film formed on the surface. The microcapsules prepared could be used as an enteric micro-probiotic-carrier for designing potential probiotic delivery systems.

Poster – 12: Radiological assessment of the secondary barrier shielding for IMRT treatments delivered through patient inhomogeneities

Purpose:To assess the impact of radiation treatment delivery through patient inhomogeneities on the secondary barrier shielding requirements in IMRT treatments using Monte Carlo Simulations.Materials and Methods:Scatter factors were calculated at a distance of 1m from the center of a virtual phantom in Geant4.10.01. Phantom (30×30×30 cm3) was inserted with lung (30×30×8 cm3), stainless steel (5×5×5 cm3) and aluminum (5×5×5 cm3) to represent the inhomogeneities. Scatter factor was defined according to the NCRP‐151 recommendations and was calculated for angles of 3° to 120° with respect to the beam's central axis. A virtual radiation source, with energy sampled from a histogram representing 6 MV FFF beam, was used for irradiation with a field size of 15×15 cm2 and SSD of 100 cm.Results:Irradiation through the inhomogeneity affects the patient scattered dose. For high Z material inhomogeneities the scattered dose is reduced due to significant attenuation of the primary radiation. On the other hand if the inhomogeneity is a low Z material such as lung the scattered dose is higher by a maximum of 26%. The average increase in scatter factors for the lung phantom was 17% for angles between 3° and 63° compared to the homogeneous water phantom.Conclusions:In IMRT type treatments delivered through low density patient inhomogeneities (lung) the scattered dose increases significantly. Considering a large proportion of patients receiving radiation therapy for lung cancers the increase in the scattered dose should be incorporated in the shielding calculations for the secondary barriers.

Autonomous mobile lock-in thermography system for detecting and quantifying voids in liquefied natural gas cargo tank second barrier

In this study, an autonomous mobile inspection system that can detect and quantify hidden voids in a secondary barrier (triplex layer) of a liquefied natural gas cargo tank is developed using lock-in thermography. The triplex layer is the secondary barrier to prevent gas leaks from a Mark III–type membrane liquefied natural gas carrier cargo tank and consists of three sub-layers: a flexible secondary barrier, a bonding layer, and a rigid secondary barrier. The proposed mobile inspection system consists of a lock-in thermography measurement unit, a mobile inspection unit, and image processing algorithms. First, thermal images are obtained using the lock-in thermography unit as the mobile inspection system maneuvers over triplex layers. Second, the raw thermal images are processed by several image processing techniques to compensate for non-uniform heating, eliminate noise components, and disregard trivial voids in accordance with the current inspection guideline. Third, the void size is more precisely quantified using an empirical mapping function that relates the void size estimated in the previous step to that measured by an independent X-ray test. The contributions of this study include the following: (1) an autonomous mobile inspection system is developed for real-time inspection of the triplex during its installation, significantly saving the inspection cost and time; (2) a suite of image processing techniques is developed, overcoming shortcomings of the existing thermography non-destructive testing techniques; and (3) the sizes as well as the locations of the hidden voids are quantified with high accuracy, reliability, and fast inspection speed.

Resistance switching memory characteristics of CaF2/Si/CaF2 resonant-tunneling quantum-well heterostructures sandwiched by nanocrystalline Si secondary barrier layers

A novel resistance switching memory using CaF2/Si/CaF2 resonant-tunneling quantum well heterostructures sandwiched by nanocrystalline Si (nc-Si) as secondary barrier layers has been proposed and the room temperature current–voltage characteristics of the basic resistance switching memory operation have been demonstrated. A resistance switching voltage of 1.0 V, a peak current density of approximately 42 kA/cm2, and an ON/OFF ratio of 2.8 were observed. In particular, more than 28000 write-read-erase cyclic memory operations have been demonstrated by applying pulsed input voltage sequences, which suggests better endurance than the device using a CaF2/CdF2/CaF2 heterostructure.

멤브레인형 LNG 화물창 개발을 위한 정적 구조 안전성 평가 모델 연구

A new concept of membrane type LNG CCS was proposed. Also, its static behavior was numerically analyzed considering the interaction between primary and secondary barrier together with securing device. Hull deflection was taken into account as an external load, together with temperature distribution across the barriers. The suggested numerical model considers both sliding and contact between the two mating surfaces of both the primary and secondary barrier, and anisotropic material behavior of plywood, R-PUF was also taken into account. Furthermore, detailed local strength was evaluated for the securing device, which is arranged between two barriers to hold the primary barrier. It was confirmed through the numerical analysis that the new concept of membrane type CCS was structurally safe under static loading condition and securing concept was structurally reliable.

The Influence of Heating Time and Temperature on the Properties of CIGSSe Solar Cells

Nonencapsulated CIGSSe solar cells, with a silver grid, were exposed to different temperatures for various periods in order to measure the effect of the heat exposure in CIGSSe modules. The heat treatment time and temperature were varied during the experiments, which were executed at atmospheric conditions. In all the cases, after reaching a temperature of about 300°C, theIVmeasurement showed a reduction of 2-3% in terms ofVOCandJSC. This is confirmed, respectively, by Raman and EQE measurements as well. The efficiency drop was −7%, −29%, and −48%, respectively, for 30 seconds, 300 seconds, and 600 seconds of exposure time. With temperatures larger than 225°C, the series resistance starts to increase exponentially and a secondary barrier becomes visible in theIVcurve. This barrier prevents the extraction of electrons and consequently reducing the solar cells efficiency. Lock-in thermography demonstrated the formation of shunts on the mechanical scribes only for 300 and 600 seconds exposure times. The shunt resistance reduction is in the range of 5% for all time periods.

Design of barrier coatings on kink-resistant peripheral nerve conduits

Here, we report on the design of braided peripheral nerve conduits with barrier coatings. Braiding of extruded polymer fibers generates nerve conduits with excellent mechanical properties, high flexibility, and significant kink-resistance. However, braiding also results in variable levels of porosity in the conduit wall, which can lead to the infiltration of fibrous tissue into the interior of the conduit. This problem can be controlled by the application of secondary barrier coatings. Using a critical size defect in a rat sciatic nerve model, the importance of controlling the porosity of the nerve conduit walls was explored. Braided conduits without barrier coatings allowed cellular infiltration that limited nerve recovery. Several types of secondary barrier coatings were tested in animal studies, including (1) electrospinning a layer of polymer fibers onto the surface of the conduit and (2) coating the conduit with a cross-linked hyaluronic acid-based hydrogel. Sixteen weeks after implantation, hyaluronic acid-coated conduits had higher axonal density, displayed higher muscle weight, and better electrophysiological signal recovery than uncoated conduits or conduits having an electrospun layer of polymer fibers. This study indicates that braiding is a promising method of fabrication to improve the mechanical properties of peripheral nerve conduits and demonstrates the need to control the porosity of the conduit wall to optimize functional nerve recovery.

Safe bunker designing for the 18 MV Varian 2100 Clinac: a comparison between Monte Carlo simulation based upon data and new protocol recommendations

AimThe aim of this study was to compare two bunkers designed by only protocols recommendations and Monte Carlo (MC) based upon data derived for an 18MV Varian 2100Clinac accelerator. BackgroundHigh energy radiation therapy is associated with fast and thermal photoneutrons. Adequate shielding against the contaminant neutron has been recommended by IAEA and NCRP new protocols. Materials and methodsThe latest protocols released by the IAEA (safety report No. 47) and NCRP report No. 151 were used for the bunker designing calculations. MC method based upon data was also derived. Two bunkers using protocols and MC upon data were designed and discussed. ResultsFrom designed door's thickness, the door designed by the MC simulation and Wu–McGinley analytical method was closer in both BPE and lead thickness. In the case of the primary and secondary barriers, MC simulation resulted in 440.11mm for the ordinary concrete, total concrete thickness of 1709mm was required. Calculating the same parameters value with the recommended analytical methods resulted in 1762mm for the required thickness using 445mm as recommended by TVL for the concrete. Additionally, for the secondary barrier the thickness of 752.05mm was obtained. ConclusionOur results showed MC simulation and the followed protocols recommendations in dose calculation are in good agreement in the radiation contamination dose calculation. Difference between the two analytical and MC simulation methods revealed that the application of only one method for the bunker design may lead to underestimation or overestimation in dose and shielding calculations.

Epidermal barrier in hereditary ichthyoses, atopic dermatitis, and psoriasis.

Several skin disorders are associated with impaired skin barrier function. Primary dysfunction is caused by monogenic defects in key components of the epidermis (for example ichthyoses). Secondary barrier impairment occurs in inflammatory dermatoses marked by disturbed epidermal homeostasis (eczema, psoriasis, etc.). In these disorders, inflammation impedes the synthesis or maintenance of skin barrier components. Recent evidence suggests a combination of primary and secondary barrier dysfunction in atopic dermatitis and, to a lesser extent, also in psoriasis. In the future, subtypes of atopic dermatitis may likely be defined, in which one or the other is prevalent.

Technology Update: Using Schematics for Managing Well Barriers

Technology Update Well integrity and well barriers have been part of the exploitation for oil and gas for nearly a century, with the introduction of the blowout preventer (BOP) in the 1920s. The concept of creating well barrier schematics was inaugurated in Norway in 1992, long before the accidents on the Montara platform in 2009 and the Deepwater Horizon rig in 2010 elevated the global focus on well integrity. A Common Understanding Yet there are large variations in the industry’s perception of well integrity and well barriers, despite the daily use of these terms by drilling and well engineers. Well integrity is defined by the Norsok Standard D-010 (Rev. 4, 2013) as an “application of technical, operational, and organizational solutions to reduce risk of uncontrolled release of formation fluids and well fluids throughout the life cycle of a well.” The definition is so broad that engineers might prefer something that lends itself to a more practical, hands-on description. This is where the well barriers principle comes into play. If you ask someone what a well barrier is, you will get many different answers. However, it is possible to unify them on the concept of an envelope. The well barrier envelope is the physical system that prevents fluids from flowing unintentionally from the formation into another formation or to the external environment. The envelope is designed to contain this pressurized effluent. Barrier Envelope Principle The benefit of using the envelope principle is that we can create two independent envelopes, one outside of the other. We will have primary containment of the pressurized fluid, so that no matter where the pressure might escape through the primary barrier, there will always be a secondary containment behind the primary barrier as a backup (Figs. 1a and 1b). To be consistent and to avoid ambiguity, it is best to define the secondary barrier as the last line of defense rather than barrier No. 2.

Water Vapor Sorption and Diffusion in Secondary Dispersion Barrier Coatings: A Critical Comparison with Emulsion Polymers.

The conventional method for synthesizing waterborne polymer colloids is emulsion polymerization using surfactants. An emerging method is the use of secondary dispersions (SD) of polymers in water, which avoids the addition of any surfactant. Although there are numerous studies of the water barrier properties (sorption, diffusion, and permeability) of waterborne emulsion (Em) polymer coatings, the properties of SD coatings, in comparison, have not been thoroughly investigated. Here, dynamic water vapor sorption analysis is used to compare the equilibrium sorption isotherms of the two forms of styrene-acrylate copolymers (Em and SD) with the same monomer composition. From an analysis of the kinetics of vapor sorption, the diffusion coefficient of water in the polymer coatings is determined. The combined effects of particle boundaries and surfactant addition were investigated through a comparison of the properties of SD and Em coatings to those of (1) solvent-cast polymer coatings (of the same monomer composition), (2) Em polymers that underwent dialysis to partially remove the water-soluble species, and (3) SD polymers with added surfactants. The results reveal that both the particle boundaries and the surfactants increase vapor sorption. The diffusion coefficients of water are comparable in magnitude in all of the polymer systems but are inversely related to water activity because of molecular clustering. Compared to all of the other waterborne polymer systems, the SD barrier coatings show the lowest equilibrium vapor sorption and permeability coefficients at high relative humidities as well as the lowest water diffusion coefficient at low humidities. These barrier properties make SD coatings an attractive alternative to conventional emulsion polymer coatings.

Optimizing the secondary mirror structure parameters for Cassegrain antenna

Cassegrain antenna is a very important type of optical antenna, which is widely used in space optical communications. However, the secondary mirror barrier may cause lower transmission efficiency in practice. This paper studies the factors affecting the transmission efficiency of the Cassegrain antenna system. Then, a series of optimum structure parameters are obtained, achieving a transmission efficiency of 91.6%. Therefore, this antenna can increase the transmission efficiency to a great extent in optical communication systems.

Control of Histamine-Producing Bacteria and Histamine Formation in Fish Muscle by Trisodium Phosphate.

Scombrotoxin fish poisoning remains the primary cause of seafood poisoning outbreaks despite preventive guidelines. The purpose of this study was to investigate the use of pH for the control of growth and histamine formation by histamine-producing bacteria in fish muscle. We examined pH effects on growth and histamine formation in tuna fish infusion broth and in inoculated tuna and mahi-mahi fish muscle. Histamine production was significantly less for all bacterial strains at pH 8.5 compared to pH 5.5 in tuna fish infusion broth with no significant difference in growth. Elevated pH due to phosphate treatment of fish muscle tissues significantly reduced histamine formation with no effect on the growth of histamine-producing bacteria. This study revealed that phosphate treatment of mahi-mahi and tuna fish muscle resulted in significantly lower histamine production over 4 d of storage at 10 °C. Phosphate treatment of fish muscle may serve as a secondary barrier in addition to FDA recommended time and temperature controls for reducing public health concerns of scombrotoxin fish poisoning.

The Efficiency of Non-Flammable Functional Underwear

Abstract This study evaluates the efficiency of non-flammable functional underwear used as a secondary heat barrier in extreme conditions. Five groups of knitted fabrics were analysed for flame resistance and selected physiological properties (water vapour permeability, air permeability, thermal resistance and liquid moisture transport by moisture management transport). The results indicated similar levels of flame resistance for the materials tested but show important differences in terms of physiological characteristics, namely liquid moisture transport, which influences the safety and comfort of protective clothing.

Molybdenum doped titanium dioxide photocatalytic coatings for use as hygienic surfaces: the effect of soiling on antimicrobial activity

Titanium dioxide (TiO2) surfaces doped with molybdenum (Mo) were investigated to determine if their photocatalytic ability could enhance process hygiene in the brewery industry. Doping TiO2 with Mo showed a 5-log reduction in bacterial counts within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h. The presence of a dilute brewery soil on the surface did not interfere with antimicrobial activity. The TiO2–Mo surface was also active in the dark, showing a 5-log reduction in bacteria within 4 to 24 h and a 1-log reduction in yeast numbers within 72 h, suggesting it could have a novel dual function, being antimicrobial and photocatalytic. The study suggests the TiO2–Mo coating could act as a secondary barrier in helping prevent the build-up of microbial contamination on surfaces within the brewery industry, in particular in between cleaning/disinfection regimes during long production runs.

SU‐E‐T‐273: Radiation Shielding for a Fixed Horizontal‐Beam Linac in a Shipping Container and a Conventional Treatment Vault

Purpose:A fixed horizontal‐beam linac, where the patient is treated in a seated position, could lower the overall costs of the treatment unit and room shielding substantially. This design also allows the treatment room and control area to be contained within a reduced space, such as a shipping container. The main application is the introduction of low‐cost, high‐quality radiation therapy to low‐ and middle‐income regions. Here we consider shielding for upright treatments with a fixed‐6MV‐beam linac in a shipping container and a conventional treatment vault.Methods:Shielding calculations were done for two treatment room layouts using calculation methods in NCRP Report 151: (1) a shipping container (6m × 2.4m with the remaining space occupied by the console area), and (2) the treatment vault in NCRP 151 (7.8m by 5.4m by 3.4m). The shipping container has a fixed gantry that points in one direction at all times. For the treatment vault, various beam directions were evaluated.Results:The shipping container requires a primary barrier of 168cm concrete (4.5 TVL), surrounded by a secondary barrier of 3.6 TVL. The other walls require between 2.8–3.3 TVL. Multiple shielding calculations were done along the side wall. The results show that patient scatter increases in the forward direction and decreases dramatically in the backward direction. Leakage scatter also varies along the wall, depending largely on the distance between the gantry and the wall. For the treatment room, fixed‐beam requires a slightly thicker primary barrier than the conventional linac (0.6 TVL), although this barrier is only needed in the center of one wall. The secondary barrier is different only by 0–0.2 TVL.Conclusion:This work shows that (1) the shipping container option is achievable, using indigenous materials for shielding and (2) upright treatments can be performed in a conventional treatment room with minimal additional shielding.Varian Medical Systems

Interface-Barrier-Induced J–V Distortion of CIGS Cells With Sputtered-Deposited Zn(S,O) Window Layers

Sputtered-deposited Zn(S,O) is an attractive alternative to CdS for the window layer of Cu(In,Ga)Se 2 (CIGS) thin-film solar cells due to its higher band gap, which allows greater blue-photon collection. However, distortions to current-voltage ( J-V) curves are observed in some cases. A straightforward photodiode model with a secondary barrier at the Zn(S,O)/CIGS interface is employed to explain the physical mechanisms of the experimental J-V distortions. The primary contributor to the secondary barrier is the conduction-band offset (CBO), whose magnitude is determined by the oxygen fraction in Zn(S,O) and by the carrier density of Zn(S,O); the latter may be increased with indium-doping. Comparison of experimental and simulated J-V characteristics with variation in oxygen fraction, window carrier density, and temperature, allows a reasonably compelling test of the secondary-barrier model for this system.