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Sample records for iron based permeable

  1. Vascular permeability and iron deposition biomarkers in longitudinal follow-up of cerebral cavernous malformations

    DEFF Research Database (Denmark)

    Girard, Romuald; Fam, Maged D; Zeineddine, Hussein A

    2017-01-01

    OBJECTIVE Vascular permeability and iron leakage are central features of cerebral cavernous malformation (CCM) pathogenesis. The authors aimed to correlate prospective clinical behavior of CCM lesions with longitudinal changes in biomarkers of dynamic contrast-enhanced quantitative permeability (...

  2. Complex permeability and permittivity variation of carbonyl iron rubber in the frequency range of 2 to 18 GHz

    Directory of Open Access Journals (Sweden)

    Adriana Medeiros Gama

    2010-04-01

    Full Text Available The complex dielectric permittivity (e and magnetic permeability (m of Radar Absorbing Materials (RAM based on metallic magnetic particles (carbonyl iron particles embedded in a dielectric matrix (silicon rubber have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of carbonyl iron-silicon composites for various mass fractions are measured by the transmission/reflection method using a vector network analyzer. The concentration dependence of permittivity and permeability on the frequency is analyzed. In a general way, the results show that e´ parameter shows a more significant variation among the evaluated parameters (e”, m”, m’. The comparison of dielectric and magnetic loss tangents (e”/e” and m”/m’, respectively shows more clearly the variation of both parameters (e and m according to the frequency. It is also observed that higher carbonyl iron content fractions favor both dielectric and magnetic loss tangents.

  3. Removal of chromate in a permeable reactive barrier using zero-valent iron

    DEFF Research Database (Denmark)

    Kjeldsen, Peter; Locht, T

    2002-01-01

    Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces by the pre......). Mixing in sand had no significant enhancing effect on the removal capacity, in contrast to a pH adjustment of the groundwater to pH 4, which significantly increased the removal capacity....

  4. Long-term Performance of Permeable Reactive Barriers Using Zero-valent Iron: An Evaluation at Two Sites

    National Research Council Canada - National Science Library

    Wilkin, Richard T; Puls, Robert W; Sewell, Guy W

    2002-01-01

    Research described in this research brief explores the geochemical and microbiological processes occurring within zero-valent iron treatment zones in permeable reactive barriers that may contribute...

  5. Zero-Valent Iron Permeable Reactive Barriers: A Review of Performance

    International Nuclear Information System (INIS)

    Korte, NE

    2001-01-01

    This report briefly reviews issues regarding the implementation of the zero-valent iron permeable reactive barrier (PRB) technology at sites managed by the U.S. Department of Energy (DOE). Initially, the PRB technology, using zero-valent iron for the reactive media, was received with great enthusiasm, and DOE invested millions of dollars testing and implementing PRBs. Recently, a negative perception of the technology has been building. This perception is based on the failure of some deployments to satisfy goals for treatment and operating expenses. The purpose of this report, therefore, is to suggest reasons for the problems that have been encountered and to recommend whether DOE should invest in additional research and deployments. The principal conclusion of this review is that the most significant problems have been the result of insufficient characterization, which resulted in poor engineering implementation. Although there are legitimate concerns regarding the longevity of the reactive media, the ability of zero-valent iron to reduce certain chlorinated hydrocarbons and to immobilize certain metals and radionuclides is well documented. The primary problem encountered at some DOE full-scale deployments has been an inadequate assessment of site hydrology, which resulted in misapplication of the technology. The result is PRBs with higher than expected flow velocities and/or incomplete plume capture

  6. Effect of iron content on permeability and power loss characteristics ...

    Indian Academy of Sciences (India)

    Administrator

    have been measured by vibrating sample magnetometer (VSM). The permeability of cadmium doped lithium ferrites exhibited higher values than zinc doped lithium ferrites. The power loss of cadmium doped lithium ferrites is lesser as compared to zinc doped lithium ferrites in the frequency range of 50–5000 kHz and at flux.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-12-22

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

  8. Transformation of Reactive Iron Minerals in a Permeable Reactive Barrier (Biowall) Used to Treat TCE in Groundwater

    Science.gov (United States)

    Abstract: Iron and sulfur reducing conditions are generally created in permeable reactive barrier (PRB) systems constructed for groundwater treatment, which usually leads to formation of iron sulfide phases. Iron sulfides have been shown to play an important role in degrading ch...

  9. Iron-based superconductivity

    CERN Document Server

    Johnson, Peter D; Yin, Wei-Guo

    2015-01-01

    This volume presents an in-depth review of experimental and theoretical studies on the newly discovered Fe-based superconductors.  Following the Introduction, which places iron-based superconductors in the context of other unconventional superconductors, the book is divided into three sections covering sample growth, experimental characterization, and theoretical understanding.  To understand the complex structure-property relationships of these materials, results from a wide range of experimental techniques and theoretical approaches are described that probe the electronic and magnetic proper

  10. Iron oxide nanoparticles induce human microvascular endothelial cell permeability through reactive oxygen species production and microtubule remodeling

    Directory of Open Access Journals (Sweden)

    Shi Xianglin

    2009-01-01

    Full Text Available Abstract Background Engineered iron nanoparticles are being explored for the development of biomedical applications and many other industry purposes. However, to date little is known concerning the precise mechanisms of translocation of iron nanoparticles into targeted tissues and organs from blood circulation, as well as the underlying implications of potential harmful health effects in human. Results The confocal microscopy imaging analysis demonstrates that exposure to engineered iron nanoparticles induces an increase in cell permeability in human microvascular endothelial cells. Our studies further reveal iron nanoparticles enhance the permeability through the production of reactive oxygen species (ROS and the stabilization of microtubules. We also showed Akt/GSK-3β signaling pathways are involved in iron nanoparticle-induced cell permeability. The inhibition of ROS demonstrate ROS play a major role in regulating Akt/GSK-3β – mediated cell permeability upon iron nanoparticle exposure. These results provide new insights into the bioreactivity of engineered iron nanoparticles which can inform potential applications in medical imaging or drug delivery. Conclusion Our results indicate that exposure to iron nanoparticles induces an increase in endothelial cell permeability through ROS oxidative stress-modulated microtubule remodeling. The findings from this study provide new understandings on the effects of nanoparticles on vascular transport of macromolecules and drugs.

  11. Neuroprotection of brain-permeable iron chelator VK-28 against intracerebral hemorrhage in mice.

    Science.gov (United States)

    Li, Qian; Wan, Jieru; Lan, Xi; Han, Xiaoning; Wang, Zhongyu; Wang, Jian

    2017-09-01

    Iron overload plays a key role in the secondary brain damage that develops after intracerebral hemorrhage (ICH). The significant increase in iron deposition is associated with the generation of reactive oxygen species (ROS), which leads to oxidative brain damage. In this study, we examined the protective effects of VK-28, a brain-permeable iron chelator, against hemoglobin toxicity in an ex vivo organotypic hippocampal slice culture (OHSC) model and in middle-aged mice subjected to an in vivo, collagenase-induced ICH model. We found that the effects of VK-28 were similar to those of deferoxamine (DFX), a well-studied iron chelator. Both decreased cell death and ROS production in OHSCs and in vivo, decreased iron-deposition and microglial activation around hematoma in vivo, and improved neurologic function. Moreover, compared with DFX, VK-28 polarized microglia to an M2-like phenotype, reduced brain water content, deceased white matter injury, improved neurobehavioral performance, and reduced overall death rate after ICH. The protection of VK-28 was confirmed in a blood-injection ICH model and in aged-male and young female mice. Our findings indicate that VK-28 is protective against iron toxicity after ICH and that, at the dosage tested, it has better efficacy and less toxicity than DFX does.

  12. Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis

    Science.gov (United States)

    VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

    2005-08-01

    Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. > 9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and δ13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched δ13C values compared to the upgradient mean. In addition, δ13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

  13. Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis.

    Science.gov (United States)

    VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

    2005-08-01

    Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. >9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and delta13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched delta13C values compared to the upgradient mean. In addition, delta13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

  14. A drainage data-based calculation method for coalbed permeability

    International Nuclear Information System (INIS)

    Lai, Feng-peng; Li, Zhi-ping; Fu, Ying-kun; Yang, Zhi-hao

    2013-01-01

    This paper establishes a drainage data-based calculation method for coalbed permeability. The method combines material balance and production equations. We use a material balance equation to derive the average pressure of the coalbed in the production process. The dimensionless water production index is introduced into the production equation for the water production stage. In the subsequent stage, which uses both gas and water, the gas and water production ratio is introduced to eliminate the effect of flush-flow radius, skin factor, and other uncertain factors in the calculation of coalbed methane permeability. The relationship between permeability and surface cumulative liquid production can be described as a single-variable cubic equation by derivation. The trend shows that the permeability initially declines and then increases after ten wells in the southern Qinshui coalbed methane field. The results show an exponential relationship between permeability and cumulative water production. The relationship between permeability and cumulative gas production is represented by a linear curve and that between permeability and surface cumulative liquid production is represented by a cubic polynomial curve. The regression result of the permeability and surface cumulative liquid production agrees with the theoretical mathematical relationship. (paper)

  15. GROUND WATER REMEDIATION OF CHROMIUM USING ZERO-VALENT IRON IN A PERMEABLE REACTIVE BARRIER

    Science.gov (United States)

    A series of laboratory experiments were performed to elucidate the chromium transformation and precipitation reactions caused by the corrosion of zero-valent iron in water-based systems. Reaction rates were determined for chromate reduction in the presence of different types of ...

  16. Uranium Removal from Groundwater by Permeable Reactive Barrier with Zero-Valent Iron and Organic Carbon Mixtures: Laboratory and Field Studies

    Directory of Open Access Journals (Sweden)

    Borys Kornilovych

    2018-06-01

    Full Text Available Zhovty Vody city, located in south-central Ukraine, has long been an important center for the Ukrainian uranium and iron industries. Uranium and iron mining and processing activities during the Cold War resulted in poorly managed sources of radionuclides and heavy metals. Widespread groundwater and surface water contamination has occurred, which creates a significant risk to drinking water supplies. Hydrogeologic and geochemical conditions near large uranium mine tailings storage facility (TSF were characterized to provide data to locate, design and install a permeable reactive barrier (PRB to treat groundwater contaminated by leachate infiltrating from the TSF. The effectiveness of three different permeable reactive materials was investigated: zero-valent iron (ZVI for reduction, sorption, and precipitation of redox-sensitive oxyanions; phosphate material to transform dissolved metals to less soluble phases; and organic carbon substrates to promote bioremediation processes. Batch and column experiments with Zhovty Vody site groundwater were conducted to evaluate reactivity of the materials. Reaction rates, residence time and comparison with site-specific clean-up standards were determined. Results of the study demonstrate the effectiveness of the use of the PRB for ground water protection near uranium mine TSF. The greatest decrease was obtained using ZVI-based reactive media and the combined media of ZVI/phosphate/organic carbon combinations.

  17. RCRA corrective measures using a permeable reactive iron wall US Coast Guard Support Center, Elizabeth City, North Carolina

    International Nuclear Information System (INIS)

    Schmithors, W.L.; Vardy, J.A.

    1997-01-01

    A chromic acid release was discovered at a former electroplating shop at the U.S. Coast Guard Support Center in Elizabeth City, North Carolina. Initial investigative activities indicated that chromic acid had migrated into the subsurface soils and groundwater. In addition, trichloroethylene (TCE) was also discovered in groundwater during subsequent investigations of the hexavalent chromium (Cr VI) plume. Corrective measures were required under the Resource Conservation and Recovery Act (RCRA). The in-situ remediation method, proposed under RCRA Interim Measures to passively treat the groundwater contaminants, uses reactive zero-valent iron to reductively dechlorinate the chlorinated compounds and to mineralize the hexavalent chromium. A 47 meter by 0.6 meter subsurface permeable iron wall was installed downgradient of the source area to a depth of 7 meters using a direct trenching machine. The iron filings were placed in the ground as the soils were excavated from the subsurface. This is the first time that direct trenching was used to install reactive zero-valent iron filings. Over 250 metric tons of iron filings were used as the reactive material in the barrier wall. Installation of the iron filings took one full day. Extensive negotiations with regulatory agencies were required to use this technology under the current facility Hazardous Waste Management Permit. All waste soils generated during the excavation activities were contained and treated on site. Once contaminant concentrations were reduced the waste soils were used as fill material

  18. Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites

    Science.gov (United States)

    Wu, Shen; Sun, Aizhi; Zhai, Fuqiang; Wang, Jin; Zhang, Qian; Xu, Wenhuan; Logan, Philip; Volinsky, Alex A.

    2012-03-01

    This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 °C increased the maximum permeability by 72.5%. The result of annealing at 580 °C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites.

  19. Magnetic permeability based diagnostic test for the determination of the canine C-reactive protein concentration in undiluted whole blood

    International Nuclear Information System (INIS)

    Ibraimi, Filiz; Kriz, Kirstin; Merin, Henrik; Kriz, Dario

    2009-01-01

    We describe an one-step 11-min magnetic permeability based two-site immunoassay for C-reactive protein (CRP) utilizing polyclonal anti-canine CRP antibody conjugated dextran iron oxide nanoparticles (79 nm) as superparamagnetic labels and polyclonal anti-canine CRP conjugated silica microparticles (15 to 40 μm) as carriers. An inductance based magnetic permeability reader was used to detect the target analyte, CRP, in 10 μL whole blood samples, by measuring the magnetic permeability increase of the silica microparticle sediment due to immuno complex superparamagnetic nanoparticles. Measurements on standards showed a linear response between 0 and 17.5 mg/L CRP. Measurements performed on 16 whole blood samples from mixed breeds showed good correlation with a commercially available ELISA assay.

  20. Effect of iron content on permeability and power loss characteristics of

    Indian Academy of Sciences (India)

    Magnetic properties like saturation magnetization, coercivity, retentivity have been measured by vibrating sample magnetometer (VSM). The permeability of cadmium doped lithium ferrites exhibited higher values than zinc doped lithium ferrites. The power loss of cadmium doped lithium ferrites is lesser as compared to zinc ...

  1. Optimum permeability for a cement based backfill material

    International Nuclear Information System (INIS)

    Jacobs, F.; Wittmann, F.H.; Iriya, K.

    1989-01-01

    In Switzerland it is planned to dispose low- and intermediate radioactive waste (LLW/ILW) in an underground repository. Between the materials present in a repository different chemical reactions may occur. Due to radiolytic decomposition, microbiological degradation and corrosion gas (mainly hydrogen) may be produced. The release of gas can cause the build-up of pressure in the cavern and finally lead to the formation of cracks and/or serious damage in the concrete structure or host rock. Through cracks a contamination of the groundwater and the biosphere could be possible. This investigation develops a suitable cement based material which can be used as backfill for the repository. Besides other aspects mentioned later a suitable backfill material has to be characterized by a certain minimum gas permeability and a as low as possible hydraulic conductivity. On the one hand gas permeability is necessary to release gas overpressure and on the other hand a low hydraulic conductivity should prevent leaching of backfill materials and contamination of the environment

  2. REMOVAL OF ADDED NITRATE IN THE SINGLE, BINARY, AND TERNARY SYSTEMS OF COTTON BURR COMPOST, ZEROVALENT IRON, AND SEDIMENT: IMPLICATIONS FOR GROUNDWATER NITRATE REMEDIATION USING PERMEABLE REACTIVE BARRIERS

    Science.gov (United States)

    Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe0) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and ...

  3. A Microring Resonator Based Negative Permeability Metamaterial Sensor

    Directory of Open Access Journals (Sweden)

    Yao-Zhong Lan

    2011-08-01

    Full Text Available Metamaterials are artificial multifunctional materials that acquire their material properties from their structure, rather than inheriting them directly from the materials they are composed of, and they may provide novel tools to significantly enhance the sensitivity and resolution of sensors. In this paper, we derive the dispersion relation of a cylindrical dielectric waveguide loaded on a negative permeability metamaterial (NPM layer, and compute the resonant frequencies and electric field distribution of the corresponding Whispering-Gallery-Modes (WGMs. The theoretical resonant frequency and electric field distribution results are in good agreement with the full wave simulation results. We show that the NPM sensor based on a microring resonator possesses higher sensitivity than the traditional microring sensor since with the evanescent wave amplification and the increase of NPM layer thickness, the sensitivity will be greatly increased. This may open a door for designing sensors with specified sensitivity.

  4. Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation

    International Nuclear Information System (INIS)

    Biermann, V.

    2007-01-01

    Elemental iron (Fe 0 ) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using 237 U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca 5 (PO 4 ) 3 OH, 99 % 0 (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe 0 columns with effluent uranium con-centrations being below the detection limit of 10 μg/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe 0 columns with 200 PV of uranium free AGW. However, columns with high Fe 0 content (≥ 50%) suffered from severe loss of permeability when AGW with ≥ 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 μg/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing from HAP surfaces. The uranium phases chernikovite and meta-ankoleite of the autunite group were identified by x-ray diffraction. The existence of these mineral phases proves that surface precipitation also occurs under favourable conditions. No uranium

  5. Progress in development of iron base alloys

    International Nuclear Information System (INIS)

    Zackay, V.V.; Parker, E.R.

    1980-01-01

    The ways of development of new iron base high-strength alloys are considered. Perspectiveness of ferritic steel strengthening with intermetallides (TaFe 2 , for instance) is shown. Favourable combination of plasticity, strength and fracture toughness in nickel-free iron-manganese alloys (16-20%) is also pointed out. A strength level of alloyed maraging steels can be achieved by changes in chemical composition and by proper heat treatments of low- and medium-alloyed steels

  6. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  7. Silane surface modification effects on the electromagnetic properties of phosphatized iron-based SMCs

    Science.gov (United States)

    Fan, Liang-Fang; Hsiang, Hsing-I.; Hung, Jia-Jing

    2018-03-01

    It is difficult to achieve homogeneous phosphatized iron powder dispersion in organic resins during the preparation of soft magnetic composites (SMCs). Inhomogeneous iron powder mixing in organic resins generally leads to the formation of micro-structural defects in SMCs and hence causes the magnetic properties to become worse. Phosphatized iron powder dispersion in organic resins can be improved by coating the phosphatized iron powder surfaces with a coupling agent. This study investigated the (3-aminopropyl) triethoxysilane (APTES) surface modification effects on the electromagnetic properties of phosphatized iron-based soft magnetic composites (SMCs). The results showed that the phosphatized iron powder surface can be modified using APTES to improve the phosphatized iron powder and epoxy resin compatibility and hence enhance phosphate iron powder epoxy mixing. The tensile strength, initial permeability, rated current under DC-bias superposition and magnetic loss in SMCs prepared using phosphatized iron powders can be effectively improved using APTES surface modification, which provides a promising candidate for power chip inductor applications.

  8. Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites

    International Nuclear Information System (INIS)

    Wu Shen; Sun Aizhi; Zhai Fuqiang; Wang Jin; Zhang Qian; Xu Wenhuan; Logan, Philip; Volinsky, Alex A.

    2012-01-01

    This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 °C increased the maximum permeability by 72.5%. The result of annealing at 580 °C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites. - Highlights: ► Silicone uniformly coated the powder, increased the operating frequency of SMCs. ► The annealing treatment increased the DC properties of SMCs. ► Annealing at 580 °C increased the maximum permeability by 72.5%. ► Compared with epoxy coated, the SMCs had higher resistivity annealing at 580 °C.

  9. A non-erasable magnetic memory based on the magnetic permeability

    International Nuclear Information System (INIS)

    Petrie, J.R.; Wieland, K.A.; Burke, R.A.; Newburgh, G.A.; Burnette, J.E.; Fischer, G.A.; Edelstein, A.S.

    2014-01-01

    A non-erasable memory based on using differences in the magnetic permeability is demonstrated. The method can potentially store information indefinitely. Initially the high permeability bits were 10–50 μm wide lines of sputtered permalloy (Ni 81 Fe 19 ) on a glass substrate. In a second writing technique a continuous film of amorphous, high permeability ferromagnetic Metglas (Fe 78 Si 13 B 9 ) was sputtered onto a similar glass substrate. Low permeability, crystalline 50 μm wide lines were then written in the film by laser heating. Both types of written media were read by applying an external probe field that is locally modified by the permeability of each bit. The modifications in the probe field were read by a nearby set of 10 micron wide magnetic tunnel junctions with a signal-to-noise ratio of up to 45 dB. This large response to changes in bit permeability is not altered after the media has been exposed to a 6400 Oe field. While being immediately applicable for data archiving and secure information storage, higher densities are possible with smaller read and write heads. - Highlights: • We demonstrate a non-erasable memory based on changes in the magnetic permeability. • Large change in permeability occur when Metglas changes from amorphous to crystalline. • Micron size regions of Metglas can be crystallized using a laser. • Permeability changes read by observing deviations of a probe field with an MTJ

  10. Theoretical analyses of superconductivity in iron based ...

    African Journals Online (AJOL)

    This paper focuses on the theoretical analysis of superconductivity in iron based superconductor Ba1−xKxFe2As2. After reviewing the current findings on this system, we suggest that phononexciton combined mechanism gives a right order of superconducting transition temperature (TC) for Ba1−xKxFe2As2 . By developing ...

  11. Effects of a Dicalcium and Tetracalcium Phosphate-Based Desensitizer on In Vitro Dentin Permeability.

    Directory of Open Access Journals (Sweden)

    Jianfeng Zhou

    Full Text Available The present study evaluated the effectiveness of a dicalcium and tetracalcium phosphate-based desensitizer in reducing dentin permeability in vitro. Dentin fluid flow was measured before and after treatment of dentin with patent dentinal tubules using 1 or 3 applications of the dicalcium and tetracalcium phosphate containing agent TeethmateTM (TM and comparing the results with two sodium fluoride varnishes VellaTM (VLA and VanishTM (VAN, after storage in artificial saliva for 24 h, 48 h and 7 days. Significant differences were observed among the 4 methods employed for reducing dentin permeability (p < 0.001 and the 3 post-treatment times (p < 0.001. VLA and VAN never achieved 50% permeability reductions consistently in any of the 3 time periods. Only the calcium phosphate-based desensitizer applied for 3 times consistently reduced dentin permeability by 50% after 24 h. When applied once, the permeability reduction of TM increased progressively over the 3 time periods. After 7 days, only one and three applications of the calcium phosphate-based desensitizer consistently reduced dentin permeability by more than 50%. Permeability reductions corresponded well with scanning electron microscopy examination of dentinal tubule orifice occlusion in dentin specimens treated with the agents. Overall, the dicalcium and tetracalcium phosphate-based desensitizer is effective in reducing dentin permeability via a tubule occlusion mechanism. The ability of the agent to reduce dentin permeability renders it to be potentially useful as a clinical dentin desensitizing agent, which has to be confirmed in future clinical studies. By contrast, the two sodium fluoride varnishes are not effective in dentin permeability reduction and should be considered as topical fluoride delivering agents rather than tubular orifice-blocking agents.

  12. Optical conductivity of iron-based superconductors

    International Nuclear Information System (INIS)

    Charnukha, A

    2014-01-01

    The new family of unconventional iron-based superconductors discovered in 2006 immediately relieved their copper-based high-temperature predecessors as the most actively studied superconducting compounds in the world. The experimental and theoretical effort made in order to unravel the mechanism of superconductivity in these materials has been overwhelming. Although our understanding of their microscopic properties has been improving steadily, the pairing mechanism giving rise to superconducting transition temperatures up to 55 K remains elusive. And yet the hope is strong that these materials, which possess a drastically different electronic structure but similarly high transition temperatures compared to the copper-based compounds, will shed essential new light onto the several-decade-old problem of unconventional superconductivity. In this work we review the current understanding of the itinerant-charge-carrier dynamics in the iron-based superconductors and parent compounds largely based on the optical-conductivity data the community has gleaned over the past seven years using such experimental techniques as reflectivity, ellipsometry, and terahertz transmission measurements and analyze the implications of these studies for the microscopic properties of the iron-based materials as well as the mechanism of superconductivity therein. (topical review)

  13. The system of thermoelectric air conditioning based on permeable thermoelements

    Directory of Open Access Journals (Sweden)

    Cherkez R. G.

    2009-04-01

    Full Text Available There is thermoelectric air conditioner unit on the basis of permeable cooling thermoelements presented. In thermoelectric air conditioner unit the thermoelectric effects and the Joule–Thomson effect have been used for the air stream cooling. There have been described the method of temperature distribution analysis, the determinations of energy conversion power characteristics and design style of permeable thermoelement with maximum coefficient of performance described. The results of computer analysis concerning the application of the thermoelement legs material on the basis of Bi2Te3 have shown the possibility of coefficient of performance increase by a factor of 1,6—1,7 as compared with conventional thermoelectric systems.

  14. Improved permeability of acyclovir: optimization of mucoadhesive liposomes using the phospholipid vesicle-based permeation assay.

    Science.gov (United States)

    Naderkhani, Elenaz; Erber, Astrid; Škalko-Basnet, Nataša; Flaten, Gøril Eide

    2014-02-01

    The antiviral drug acyclovir (ACV) suffers from poor solubility both in lipophilic and hydrophilic environment, leading to low and highly variable bioavailability. To overcome these limitations, this study aimed at designing mucoadhesive ACV-containing liposomes to improve its permeability. Liposomes were prepared from egg phosphatidylcholine (E-PC) and E-PC/egg phosphatidylglycerol (E-PC/E-PG) and their surfaces coated with Carbopol. All liposomal formulations were fully characterized and for the first time the phospholipid vesicle-based permeation assay (PVPA) was used for testing in vitro permeability of drug from mucoadhesive liposome formulations. The negatively charged E-PC/E-PG liposomes could encapsulate more ACV than neutral E-PC liposomes. Coating with Carbopol increased the entrapment in the neutral E-PC liposomes. The incorporation of ACV into liposomes exhibited significant increase in its in vitro permeability, compared with its aqueous solution. The neutral E-PC liposomal formulations exhibited higher ACV permeability values compared with charged E-PC/E-PG formulations. Coating with Carbopol significantly enhanced the permeability from the E-PC/E-PG liposomes, as well as sonicated E-PC liposomes, which showed the highest permeability of all tested formulations. The increased permeability was according to the formulations' mucoadhesive properties. This indicates that the PVPA is suitable to distinguish between permeability of ACV from different mucoadhesive liposome formulations developed for various routes of administration. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  15. Discovery of a new mitochondria permeability transition pore (mPTP) inhibitor based on gallic acid.

    Science.gov (United States)

    Teixeira, José; Oliveira, Catarina; Cagide, Fernando; Amorim, Ricardo; Garrido, Jorge; Borges, Fernanda; Oliveira, Paulo J

    2018-12-01

    Pharmacological interventions targeting mitochondria present several barriers for a complete efficacy. Therefore, a new mitochondriotropic antioxidant (AntiOxBEN 3 ) based on the dietary antioxidant gallic acid was developed. AntiOxBEN 3 accumulated several thousand-fold inside isolated rat liver mitochondria, without causing disruption of the oxidative phosphorylation apparatus, as seen by the unchanged respiratory control ratio, phosphorylation efficiency, and transmembrane electric potential. AntiOxBEN 3 showed also limited toxicity on human hepatocarcinoma cells. Moreover, AntiOxBEN 3 presented robust iron-chelation and antioxidant properties in both isolated liver mitochondria and cultured rat and human cell lines. Along with its low toxicity profile and high antioxidant activity, AntiOxBEN 3 strongly inhibited the calcium-dependent mitochondrial permeability transition pore (mPTP) opening. From our data, AntiOxBEN 3 can be considered as a lead compound for the development of a new class of mPTP inhibitors and be used as mPTP de-sensitiser for basic research or clinical applications or emerge as a therapeutic application in mitochondria dysfunction-related disorders.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  17. An improved method for permeability estimation of the bioclastic limestone reservoir based on NMR data.

    Science.gov (United States)

    Ge, Xinmin; Fan, Yiren; Liu, Jianyu; Zhang, Li; Han, Yujiao; Xing, Donghui

    2017-10-01

    Permeability is an important parameter in formation evaluation since it controls the fluid transportation of porous rocks. However, it is challengeable to compute the permeability of bioclastic limestone reservoirs by conventional methods linking petrophysical and geophysical data, due to the complex pore distributions. A new method is presented to estimate the permeability based on laboratory and downhole nuclear magnetic resonance (NMR) measurements. We divide the pore space into four intervals by the inflection points between the pore radius and the transversal relaxation time. Relationships between permeability and percentages of different pore intervals are investigated to investigate influential factors on the fluid transportation. Furthermore, an empirical model, which takes into account of the pore size distributions, is presented to compute the permeability. 212 core samples in our case show that the accuracy of permeability calculation is improved from 0.542 (SDR model), 0.507 (TIM model), 0.455 (conventional porosity-permeability regressions) to 0.803. To enhance the precision of downhole application of the new model, we developed a fluid correction algorithm to construct the water spectrum of in-situ NMR data, aiming to eliminate the influence of oil on the magnetization. The result reveals that permeability is positively correlated with percentages of mega-pores and macro-pores, but negatively correlated with the percentage of micro-pores. Poor correlation is observed between permeability and the percentage of meso-pores. NMR magnetizations and T 2 spectrums after the fluid correction agree well with laboratory results for samples saturated with water. Field application indicates that the improved method provides better performance than conventional models such as Schlumberger-Doll Research equation, Timur-Coates equation, and porosity-permeability regressions. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. An improved method for permeability estimation of the bioclastic limestone reservoir based on NMR data

    Science.gov (United States)

    Ge, Xinmin; Fan, Yiren; Liu, Jianyu; Zhang, Li; Han, Yujiao; Xing, Donghui

    2017-10-01

    Permeability is an important parameter in formation evaluation since it controls the fluid transportation of porous rocks. However, it is challengeable to compute the permeability of bioclastic limestone reservoirs by conventional methods linking petrophysical and geophysical data, due to the complex pore distributions. A new method is presented to estimate the permeability based on laboratory and downhole nuclear magnetic resonance (NMR) measurements. We divide the pore space into four intervals by the inflection points between the pore radius and the transversal relaxation time. Relationships between permeability and percentages of different pore intervals are investigated to investigate influential factors on the fluid transportation. Furthermore, an empirical model, which takes into account of the pore size distributions, is presented to compute the permeability. 212 core samples in our case show that the accuracy of permeability calculation is improved from 0.542 (SDR model), 0.507 (TIM model), 0.455 (conventional porosity-permeability regressions) to 0.803. To enhance the precision of downhole application of the new model, we developed a fluid correction algorithm to construct the water spectrum of in-situ NMR data, aiming to eliminate the influence of oil on the magnetization. The result reveals that permeability is positively correlated with percentages of mega-pores and macro-pores, but negatively correlated with the percentage of micro-pores. Poor correlation is observed between permeability and the percentage of meso-pores. NMR magnetizations and T2 spectrums after the fluid correction agree well with laboratory results for samples saturated with water. Field application indicates that the improved method provides better performance than conventional models such as Schlumberger-Doll Research equation, Timur-Coates equation, and porosity-permeability regressions.

  19. Iron-based soft magnetic composites with Mn-Zn ferrite nanoparticles coating obtained by sol-gel method

    Science.gov (United States)

    Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

    2012-11-01

    This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn-Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol-gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn-Zn ferrites. Mn-Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn-Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn-Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

  20. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

    Energy Technology Data Exchange (ETDEWEB)

    Yang Ji, E-mail: yangji@ecust.edu.cn [School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Cao Limei; Guo Rui; Jia Jinping [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-12-15

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m{sup 2} g{sup -1}, the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

  1. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

    International Nuclear Information System (INIS)

    Yang Ji; Cao Limei; Guo Rui; Jia Jinping

    2010-01-01

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m 2 g -1 , the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

  2. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

    Science.gov (United States)

    Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

    2010-12-15

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Iron-based soft magnetic composites with Mn–Zn ferrite nanoparticles coating obtained by sol–gel method

    International Nuclear Information System (INIS)

    Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

    2012-01-01

    This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn–Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol–gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn–Zn ferrites. Mn–Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn–Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn–Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability. - Highlights: ► Uniformly coated Mn–Zn ferrite powder increased the operating frequency of SMCs. ► Compared with epoxy coated, the permeability of SMCs increased by 33.5% at 10 kHz. ► 400 °C is the optimum annealing temperature to attain the desired permeability.

  4. Permeability Estimation of Rock Reservoir Based on PCA and Elman Neural Networks

    Science.gov (United States)

    Shi, Ying; Jian, Shaoyong

    2018-03-01

    an intelligent method which based on fuzzy neural networks with PCA algorithm, is proposed to estimate the permeability of rock reservoir. First, the dimensionality reduction process is utilized for these parameters by principal component analysis method. Further, the mapping relationship between rock slice characteristic parameters and permeability had been found through fuzzy neural networks. The estimation validity and reliability for this method were tested with practical data from Yan’an region in Ordos Basin. The result showed that the average relative errors of permeability estimation for this method is 6.25%, and this method had the better convergence speed and more accuracy than other. Therefore, by using the cheap rock slice related information, the permeability of rock reservoir can be estimated efficiently and accurately, and it is of high reliability, practicability and application prospect.

  5. Microstructure-based characterization of permeability using a random walk model

    International Nuclear Information System (INIS)

    Chen, F F; Yang, Y S

    2012-01-01

    Quantitative transport properties of materials are analysed using a random walk model, based on the microscopic compositional distribution of compositions in the materials. A material sample is defined on a simple-cubic lattice, with volume fractions specified for each composition on every volume pixel (voxel). The quantitative relation between bulk permeability and fine-scale anisotropy is investigated by assuming fully anisotropic and fully isotropic voxel morphology. Such a study has prompted an analytic approximate formulation to predict bulk permeability range for a heterogeneous multi-component system that lacks detailed microstructure information. The numerical approach is verified on synthetic structures with known permeability. The analysis technique is applied to a real-world rock sample, as illustrated by a case study detailed in this paper. The investigations show that the bulk permeability is affected significantly by fine length scale anisotropy. (paper)

  6. Research on the performance of sand-based environmental-friendly water permeable bricks

    Science.gov (United States)

    Cai, Runze; Mandula; Chai, Jinyi

    2018-02-01

    This paper examines the effects of the amount of admixture, the water cement ratio, the aggregate grading, and the cement aggregate ratio on the mechanical service properties and of porous concrete pavement bricks including strength, water permeability, frost resistance, and wear resistance. The admixture can enhance the performance of water permeable brick, and optimize the design mix. Experiments are conducted to determine the optimal mixing ratios which are given as; (1) the admixture (self-developed) within the content of 5% of the cement quality; (2) water-cement ratio equal to 0.34; (3) cement-aggregate ratio equal to 0.25; (4) fine aggregate of 70% (particle size 0.6-2.36mm); and coarse aggregate of 30% (particle size: 2.36-4.75mm). The experimental results that the sand-based permeable concrete pavement brick has a strength of 35.6MPa and that the water permeability coefficient is equal to 3.5×10-2cm/s. In addition, it was found that the concrete water permeable brick has good frost resistance and surface wear resistance, and that the its production costs are much lower than the similar sand-based water permeable bricks in China.

  7. Urban permeable pavement system design based on “sponge city” concept

    Science.gov (United States)

    Yu, M. M.; Zhu, J. W.; Gao, W. F.; Xu, D. P.; Zhao, M.

    2017-08-01

    Based on the “sponge city” concept, to implement the goal of building a city within the city to solve the sponge waterlogging, rational utilization of water resources, reduce water pollution this paper, combined with the city planning level in China, establishes the design system of city road flooding from the macro, medium and micro level, explore the design method of city water permeable pavement system, and has a practical significance the lower flood risk water ecological problems. On the macro level, we established an urban pavement sponge system under the regional ecological pattern by “spot permeable open space - low impact developing rain water road system - catchment area and catchment wetland”. On a medium level, this paper proposed the permeable suitability of pavement and the planning control indicators when combined with urban functional districts to conduct permeable pavement roads plans and controls. On micro level, the paper studied sponge technology design of permeable pavement from road structure, surface material, and other aspects aimed at the pavement permeability requirements.

  8. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  9. a Predictive Model of Permeability for Fractal-Based Rough Rock Fractures during Shear

    Science.gov (United States)

    Huang, Na; Jiang, Yujing; Liu, Richeng; Li, Bo; Zhang, Zhenyu

    This study investigates the roles of fracture roughness, normal stress and shear displacement on the fluid flow characteristics through three-dimensional (3D) self-affine fractal rock fractures, whose surfaces are generated using the modified successive random additions (SRA) algorithm. A series of numerical shear-flow tests under different normal stresses were conducted on rough rock fractures to calculate the evolutions of fracture aperture and permeability. The results show that the rough surfaces of fractal-based fractures can be described using the scaling parameter Hurst exponent (H), in which H = 3 - Df, where Df is the fractal dimension of 3D single fractures. The joint roughness coefficient (JRC) distribution of fracture profiles follows a Gauss function with a negative linear relationship between H and average JRC. The frequency curves of aperture distributions change from sharp to flat with increasing shear displacement, indicating a more anisotropic and heterogeneous flow pattern. Both the mean aperture and permeability of fracture increase with the increment of surface roughness and decrement of normal stress. At the beginning of shear, the permeability increases remarkably and then gradually becomes steady. A predictive model of permeability using the mean mechanical aperture is proposed and the validity is verified by comparisons with the experimental results reported in literature. The proposed model provides a simple method to approximate permeability of fractal-based rough rock fractures during shear using fracture aperture distribution that can be easily obtained from digitized fracture surface information.

  10. LONG-TERM GEOCHEMICAL BEHAVIOR OF A ZEROVALENT IRON PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM IN GROUNDWATER

    Science.gov (United States)

    Passive, in-situ reactive barriers have proven to be viable, cost-effective systems for the remediation of Cr-contaminated groundwater at some sites. Permeable reactive barriers (PRBs) are installed in the flow-path of groundwater, most typically as vertical treatment walls. Re...

  11. Experimental Study of Matrix Permeability of Gas Shale: An Application to CO2-Based Shale Fracturing

    Directory of Open Access Journals (Sweden)

    Chengpeng Zhang

    2018-03-01

    Full Text Available Because the limitations of water-based fracturing fluids restrict their fracturing efficiency and scope of application, liquid CO2 is regarded as a promising substitute, owing to its unique characteristics, including its greater environmental friendliness, shorter clean-up time, greater adsorption capacity than CH4 and less formation damage. Conversely, the disadvantage of high leak-off rate of CO2 fracturing due to its very low viscosity determines its applicability in gas shales with ultra-low permeability, accurate measurement of shale permeability to CO2 is therefore crucial to evaluate the appropriate injection rate and total consumption of CO2. The main purpose of this study is to accurately measure shale permeability to CO2 flow during hydraulic fracturing, and to compare the leak-off of CO2 and water fracturing. A series of permeability tests was conducted on cylindrical shale samples 38 mm in diameter and 19 mm long using water, CO2 in different phases and N2 considering multiple influencing factors. According to the experimental results, the apparent permeability of shale matrix to gaseous CO2 or N2 is greatly over-estimated compared with intrinsic permeability or that of liquid CO2 due to the Klinkenberg effect. This phenomenon explains that the permeability values measured under steady-state conditions are much higher than those under transient conditions. Supercritical CO2 with higher molecular kinetic energy has slightly higher permeability than liquid CO2. The leak-off rate of CO2 is an order of magnitude higher than that of water under the same injection conditions due to its lower viscosity. The significant decrease of shale permeability to gas after water flooding is due to the water block effect, and much longer clean-up time and deep water imbibition depth greatly impede the gas transport from the shale matrix to the created fractures. Therefore, it is necessary to substitute water-based fracturing fluids with liquid or super

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

    KAUST Repository

    Akhtar, Faheem Hassan

    2017-09-13

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

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

    KAUST Repository

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

    2017-01-01

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

  14. Theoretical Analyses of Superconductivity in Iron Based ...

    African Journals Online (AJOL)

    fire7-

    using double time temperature dependent Green's function formalism and a suitable decoupling approximation technique, we ... phenomenon of zero electric resistivity in mercury was soon followed by the observation of the superconducting state in ... The iron, Fe2+ forms tetrahedron within the layers. This means that, iron-.

  15. Elimination of Iron Based Particles in Al-Si Alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2015-03-01

    Full Text Available This paper deals with influence on segregation of iron based phases on the secondary alloy AlSi7Mg0.3 microstructure by chrome. Iron is the most common and harmful impurity in aluminum casting alloys and has long been associated with an increase of casting defects. In generally, iron is associated with the formation of Fe-rich phases. It is impossible to remove iron from melt by standard operations, but it is possible to eliminate its negative influence by addition some other elements that affect the segregation of intermetallics in less harmful type. Realization of experiments and results of analysis show new view on solubility of iron based phases during melt preparation with higher iron content and influence of chrome as iron corrector of iron based phases. By experimental work were used three different amounts of AlCr20 master alloy a three different temperature of chill mold. Our experimental work confirmed that chrome can be used as an iron corrector in Al-Si alloy, due to the change of intermetallic phases and shortening their length.

  16. Environmental transformations and ecological effects of iron-based nanoparticles.

    Science.gov (United States)

    Lei, Cheng; Sun, Yuqing; Tsang, Daniel C W; Lin, Daohui

    2018-01-01

    The increasing application of iron-based nanoparticles (NPs), especially high concentrations of zero-valent iron nanoparticles (nZVI), has raised concerns regarding their environmental behavior and potential ecological effects. In the environment, iron-based NPs undergo physical, chemical, and/or biological transformations as influenced by environmental factors such as pH, ions, dissolved oxygen, natural organic matter (NOM), and biotas. This review presents recent research advances on environmental transformations of iron-based NPs, and articulates their relationships with the observed toxicities. The type and extent of physical, chemical, and biological transformations, including aggregation, oxidation, and bio-reduction, depend on the properties of NPs and the receiving environment. Toxicities of iron-based NPs to bacteria, algae, fish, and plants are increasingly observed, which are evaluated with a particular focus on the underlying mechanisms. The toxicity of iron-based NPs is a function of their properties, tolerance of test organisms, and environmental conditions. Oxidative stress induced by reactive oxygen species is considered as the primary toxic mechanism of iron-based NPs. Factors influencing the toxicity of iron-based NPs are addressed and environmental transformations play a significant role, for example, surface oxidation or coating by NOM generally lowers the toxicity of nZVI. Research gaps and future directions are suggested with an aim to boost concerted research efforts on environmental transformations and toxicity of iron-based NPs, e.g., toxicity studies of transformed NPs in field, expansion of toxicity endpoints, and roles of laden contaminants and surface coating. This review will enhance our understanding of potential risks of iron-based NPs and proper uses of environmentally benign NPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. The Evidence-Based Evaluation of Iron Deficiency Anemia.

    Science.gov (United States)

    Hempel, Eliana V; Bollard, Edward R

    2016-09-01

    Anemia is a prevalent disease with multiple possible etiologies and resultant complications. Iron deficiency anemia is a common cause of anemia and is typically due to insufficient intake, poor absorption, or overt or occult blood loss. Distinguishing iron deficiency from other causes of anemia is integral to initiating the appropriate treatment. In addition, identifying the underlying cause of iron deficiency is also necessary to help guide management of these patients. We review the key components to an evidence-based, cost-conscious evaluation of suspected iron deficiency anemia. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Bayesian inference for heterogeneous caprock permeability based on above zone pressure monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Namhata, Argha; Small, Mitchell J.; Dilmore, Robert M.; Nakles, David V.; King, Seth

    2017-02-01

    The presence of faults/ fractures or highly permeable zones in the primary sealing caprock of a CO2 storage reservoir can result in leakage of CO2. Monitoring of leakage requires the capability to detect and resolve the onset, location, and volume of leakage in a systematic and timely manner. Pressure-based monitoring possesses such capabilities. This study demonstrates a basis for monitoring network design based on the characterization of CO2 leakage scenarios through an assessment of the integrity and permeability of the caprock inferred from above zone pressure measurements. Four representative heterogeneous fractured seal types are characterized to demonstrate seal permeability ranging from highly permeable to impermeable. Based on Bayesian classification theory, the probability of each fractured caprock scenario given above zone pressure measurements with measurement error is inferred. The sensitivity to injection rate and caprock thickness is also evaluated and the probability of proper classification is calculated. The time required to distinguish between above zone pressure outcomes and the associated leakage scenarios is also computed.

  19. Temperature dependence of nitrogen solubility in iron base multicomponent melts

    International Nuclear Information System (INIS)

    Sokolov, V.M.; Koval'chuk, L.A.

    1986-01-01

    Method for calculating temperature dependence of nitrogen solubility in iron base multicomponent melts is suggested. Application areas of existing methods were determined and advantages of the new method for calculating nitrogen solubility in multicomponent-doped iron melts (Fe-Ni-Cr-Mo, Fe-Ni-Cr-Mn, Fe-Mo-V) at 1773-2073 K are shown

  20. Tunable d-Limonene Permeability in Starch-Based Nanocomposite Films Reinforced by Cellulose Nanocrystals.

    Science.gov (United States)

    Liu, Siyuan; Li, Xiaoxi; Chen, Ling; Li, Lin; Li, Bing; Zhu, Jie

    2018-01-31

    In order to control d-limonene permeability, cellulose nanocrystals (CNC) were used to regulate starch-based film multiscale structures. The effect of sphere-like cellulose nanocrystal (CS) and rod-like cellulose nanocrystal (CR) on starch molecular interaction, short-range molecular conformation, crystalline structure, and micro-ordered aggregated region structure were systematically discussed. CNC aspect ratio and content were proved to be independent variables to control d-limonene permeability via film-structure regulation. New hydrogen bonding formation and increased hydroxypropyl starch (HPS) relative crystallinity could be the reason for the lower d-limonene permeability compared with tortuous path model approximation. More hydrogen bonding formation, higher HPS relative crystallinity and larger size of micro-ordered aggregated region in CS0.5 and CR2 could explain the lower d-limonene permeability than CS2 and CR0.5, respectively. This study provided new insight for the control of the flavor release from starch-based films, which favored its application in biodegradable food packaging and flavor encapsulation.

  1. Studies of anisotropy of iron based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Jason A. [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    To study the electronic anisotropy in iron based superconductors, the temperature dependent London penetration depth, Δλ(T), have been measured in several compounds, along with the angular dependent upper critical field, Hc2(T). Study was undertaken on single crystals of Ba(Fe1-xCox)2As2 with x=0.108 and x=0.127, in the overdoped range of the doping phase diagram, characterized by notable modulation of the superconducting gap. Heavy ion irradiation with matching field doses of 6 T and 6.5 T respectively, were used to create columnar defects and to study their effect on the temperature Δλ(T). The variation of the low-temperature penetration depth in both pristine and irradiated samples was fitted with a power-law function Δλ(T) = ATn. Irradiation increases the magnitude of the pre-factor A and decreases the exponent n, similar to the effect on the optimally doped samples. This finding supports the universal s ± scenario for the whole doping range.

  2. Pressure effect on iron based superconductors

    International Nuclear Information System (INIS)

    Arumugam, S.; Kanagaraj, M.

    2011-01-01

    A tuning of macroscopic thermo dynamical parameters such as temperature, pressure and volume play a crucial role in strongly correlated electron systems especially high T c superconductors, which leads to increasing conductivity as well as effective way of reducing intrinsic magnetic moments. Application of chemical and external pressure exhibits significant increases of critical temperature of recently discovered iron pnictides and chalcogenides superconductors. In this present report, we have investigated hydrostatic pressure effects on resistivity and magnetization of some 1111 type based oxypnictide superconductors such as Co doped CeFeAsO, La 0.8 Th 0.2 FeAsO, Ce 0.6 Y 0.4 FeAsO 0.8 F 0.2 and Yb doped CeFeAsO systems respectively. The initially applied pressure increases the T c and its down to lower value when beyond increasing pressure also has been observed and pressure effects on crystal structure were also discussed. From that all the obtained results reveal that controlling of magnetic instability and structure distortion at higher pressure is a dominant way to further developing of T c of these new ferropnictides compounds. (author)

  3. Automation of cell-based drug absorption assays in 96-well format using permeable support systems.

    Science.gov (United States)

    Larson, Brad; Banks, Peter; Sherman, Hilary; Rothenberg, Mark

    2012-06-01

    Cell-based drug absorption assays, such as Caco-2 and MDCK-MDR1, are an essential component of lead compound ADME/Tox testing. The permeability and transport data they provide can determine whether a compound continues in the drug discovery process. Current methods typically incorporate 24-well microplates and are performed manually. Yet the need to generate absorption data earlier in the drug discovery process, on an increasing number of compounds, is driving the use of higher density plates. A simple, more efficient process that incorporates 96-well permeable supports and proper instrumentation in an automated process provides more reproducible data compared to manual methods. Here we demonstrate the ability to perform drug permeability and transport assays using Caco-2 or MDCKII-MDR1 cells. The assay procedure was automated in a 96-well format, including cell seeding, media and buffer exchanges, compound dispense, and sample removal using simple robotic instrumentation. Cell monolayer integrity was confirmed via transepithelial electrical resistance and Lucifer yellow measurements. Proper cell function was validated by analyzing apical-to-basolateral and basolateral-to-apical movement of rhodamine 123, a known P-glycoprotein substrate. Apparent permeability and efflux data demonstrate how the automated procedure provides a less variable method than manual processing, and delivers a more accurate assessment of a compound's absorption characteristics.

  4. Method of coating an iron-based article

    Science.gov (United States)

    Magdefrau, Neal; Beals, James T.; Sun, Ellen Y.; Yamanis, Jean

    2016-11-29

    A method of coating an iron-based article includes a first heating step of heating a substrate that includes an iron-based material in the presence of an aluminum source material and halide diffusion activator. The heating is conducted in a substantially non-oxidizing environment, to cause the formation of an aluminum-rich layer in the iron-based material. In a second heating step, the substrate that has the aluminum-rich layer is heated in an oxidizing environment to oxidize the aluminum in the aluminum-rich layer.

  5. FERRIC CITRATE: AN IRON-BASED ORAL PHOSPHATE BINDER

    Directory of Open Access Journals (Sweden)

    T. Christopher Bond

    2012-06-01

    Based on actual physician behavior in response to ferritin and TSAT increases and ferric citrate clinical trial results, and assuming equivalent pricing to other PBs, there would be cost savings with ferric citrate use through reduced ESA and iron use.

  6. Mechanical properties of permeable materials with an organized structure on the base of continuous metal fibers

    International Nuclear Information System (INIS)

    Karpinos, D.M.; Rutkovskij, A.E.; Zorin, V.A.; Ivanchuk, A.A.

    1979-01-01

    The mechanical properties were studied for permeable fibrous materials with an organized structure on the base of continuous metal fibers (from Kh18N9T steel) subjected to preliminary reprocessing volumetric net half-finished products. The effect of geometrical parameters of the net half-finished products and of their orientation in packing are shown to affect the mechanical properties within a wide range of porosities

  7. Using a spin torque nano-oscillator to read memory based on the magnetic permeability

    International Nuclear Information System (INIS)

    Petrie, J R; Wieland, K A; Fischer, G A; Edelstein, A S; Urazhdin, S

    2014-01-01

    We present an archival memory utilizing a spin torque nano-oscillator (STNO) to read bits of data with different magnetic permeability. Basing a magnetic memory on this intrinsic property rather than remanent magnetization reduces the risk of data corruption. The permeability of the bits is read as changes in an applied probe field near the media. These changes in the probe field are measured by detecting microwave frequency shifts in STNOs. The probe field can be tuned over hundreds of Oe to optimize the reading of the media. Using a 400 Oe probe field, we have measured 2% frequency shifts in a STNO near micrometre-sized bits of (1) lithographically-patterned permalloy lines and (2) laser-crystallized Metglas lines. Data from either media was not corrupted by exposure to fields of 6400 Oe and temperatures of 523 K. (paper)

  8. Using a spin torque nano-oscillator to read memory based on the magnetic permeability

    Science.gov (United States)

    Petrie, J. R.; Urazhdin, S.; Wieland, K. A.; Fischer, G. A.; Edelstein, A. S.

    2014-02-01

    We present an archival memory utilizing a spin torque nano-oscillator (STNO) to read bits of data with different magnetic permeability. Basing a magnetic memory on this intrinsic property rather than remanent magnetization reduces the risk of data corruption. The permeability of the bits is read as changes in an applied probe field near the media. These changes in the probe field are measured by detecting microwave frequency shifts in STNOs. The probe field can be tuned over hundreds of Oe to optimize the reading of the media. Using a 400 Oe probe field, we have measured 2% frequency shifts in a STNO near micrometre-sized bits of (1) lithographically-patterned permalloy lines and (2) laser-crystallized Metglas lines. Data from either media was not corrupted by exposure to fields of 6400 Oe and temperatures of 523 K.

  9. Physically based model for extracting dual permeability parameters using non-Newtonian fluids

    Science.gov (United States)

    Abou Najm, M. R.; Basset, C.; Stewart, R. D.; Hauswirth, S.

    2017-12-01

    Dual permeability models are effective for the assessment of flow and transport in structured soils with two dominant structures. The major challenge to those models remains in the ability to determine appropriate and unique parameters through affordable, simple, and non-destructive methods. This study investigates the use of water and a non-Newtonian fluid in saturated flow experiments to derive physically-based parameters required for improved flow predictions using dual permeability models. We assess the ability of these two fluids to accurately estimate the representative pore sizes in dual-domain soils, by determining the effective pore sizes of macropores and micropores. We developed two sub-models that solve for the effective macropore size assuming either cylindrical (e.g., biological pores) or planar (e.g., shrinkage cracks and fissures) pore geometries, with the micropores assumed to be represented by a single effective radius. Furthermore, the model solves for the percent contribution to flow (wi) corresponding to the representative macro and micro pores. A user-friendly solver was developed to numerically solve the system of equations, given that relevant non-Newtonian viscosity models lack forms conducive to analytical integration. The proposed dual-permeability model is a unique attempt to derive physically based parameters capable of measuring dual hydraulic conductivities, and therefore may be useful in reducing parameter uncertainty and improving hydrologic model predictions.

  10. Unified Phase Diagram for Iron-Based Superconductors.

    Science.gov (United States)

    Gu, Yanhong; Liu, Zhaoyu; Xie, Tao; Zhang, Wenliang; Gong, Dongliang; Hu, Ding; Ma, Xiaoyan; Li, Chunhong; Zhao, Lingxiao; Lin, Lifang; Xu, Zhuang; Tan, Guotai; Chen, Genfu; Meng, Zi Yang; Yang, Yi-Feng; Luo, Huiqian; Li, Shiliang

    2017-10-13

    High-temperature superconductivity is closely adjacent to a long-range antiferromagnet, which is called a parent compound. In cuprates, all parent compounds are alike and carrier doping leads to superconductivity, so a unified phase diagram can be drawn. However, the properties of parent compounds for iron-based superconductors show significant diversity and both carrier and isovalent dopings can cause superconductivity, which casts doubt on the idea that there exists a unified phase diagram for them. Here we show that the ordered moments in a variety of iron pnictides are inversely proportional to the effective Curie constants of their nematic susceptibility. This unexpected scaling behavior suggests that the magnetic ground states of iron pnictides can be achieved by tuning the strength of nematic fluctuations. Therefore, a unified phase diagram can be established where superconductivity emerges from a hypothetical parent compound with a large ordered moment but weak nematic fluctuations, which suggests that iron-based superconductors are strongly correlated electron systems.

  11. Unified Phase Diagram for Iron-Based Superconductors

    Science.gov (United States)

    Gu, Yanhong; Liu, Zhaoyu; Xie, Tao; Zhang, Wenliang; Gong, Dongliang; Hu, Ding; Ma, Xiaoyan; Li, Chunhong; Zhao, Lingxiao; Lin, Lifang; Xu, Zhuang; Tan, Guotai; Chen, Genfu; Meng, Zi Yang; Yang, Yi-feng; Luo, Huiqian; Li, Shiliang

    2017-10-01

    High-temperature superconductivity is closely adjacent to a long-range antiferromagnet, which is called a parent compound. In cuprates, all parent compounds are alike and carrier doping leads to superconductivity, so a unified phase diagram can be drawn. However, the properties of parent compounds for iron-based superconductors show significant diversity and both carrier and isovalent dopings can cause superconductivity, which casts doubt on the idea that there exists a unified phase diagram for them. Here we show that the ordered moments in a variety of iron pnictides are inversely proportional to the effective Curie constants of their nematic susceptibility. This unexpected scaling behavior suggests that the magnetic ground states of iron pnictides can be achieved by tuning the strength of nematic fluctuations. Therefore, a unified phase diagram can be established where superconductivity emerges from a hypothetical parent compound with a large ordered moment but weak nematic fluctuations, which suggests that iron-based superconductors are strongly correlated electron systems.

  12. EDITORIAL: Focus on Iron-Based Superconductors FOCUS ON IRON-BASED SUPERCONDUCTORS

    Science.gov (United States)

    Hosono, Hideo; Ren, Zhi-An

    2009-02-01

    Superconductivity is the most dramatic and clear cut phenomenon in condensed matter physics. Realization of room temperature superconductors, which would lead to the revolution of our society, is an ultimate goal for researchers. The discovery of high Tc cuprate superconductors in 1986 by Bednorz and Müller triggered intensive research worldwide and the maximum critical temperature has been raised above 100 K. Scientific research on this break-through material clarified a new route to high Tc materials, carrier doping to a Mott insulator with anti-ferromagnetic ordering. High superconductivity occurs in the neighborhood of Mott-insulators and Fermi-metals. Such a view, which was completely new, now stands as a guiding principle for exploring new high Tc materials. Many theoretical approaches to the mechanism for cuprate superconductors have been carried out to understand this unexpected material and to predict new high Tc materials. In 2006 a new superconductor based on iron, LaFeOP, was discovered by a group at Tokyo Institute of Technology, Japan. Iron, as a ferromagnet, was believed to be the last element for the realization of superconductivity because of the way ferromagnetism competes against Cooper pair formation. Unexpectedly, however, the critical temperature remained at 4-6 K irrespective of hole/electron-doping. A large increase in the Tc to 26 K was then found in LaFe[O1-xFx]As by the same group (and was published on 23 February 2008, in the Journal of the American Chemical Society). The Tc of this material was further raised to 43 K under a pressure of 2 GPa and scientists in China then achieved a Tc of 56 K at ambient pressure by replacing La with other rare earth ions with smaller radius—a critical temperature that is second only to the high Tc cuprates. This fast progress has revitalized research within superconductivity and in 2008 there were more than seven international symposia specifically on Fe(Ni)-based superconductors. Through the rapid

  13. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...... of transcription factors, activation of the mitochondrial apoptotic machinery or of other cell death mechanisms. The pro-inflammatory cytokine IL-1β facilitates divalent metal transporter 1 (DMT1)-induced β-cell iron uptake and consequently ROS formation and apoptosis, and we propose that this mechanism provides...

  14. Enhanced Transdermal Permeability via Constructing the Porous Structure of Poloxamer-Based Hydrogel

    Directory of Open Access Journals (Sweden)

    Wen-Yi Wang

    2016-11-01

    Full Text Available A major concern for transdermal drug delivery systems is the low bioavailability of targeted drugs primarily caused by the skin’s barrier function. The resistance to the carrier matrix for the diffusion and transport of drugs, however, is routinely ignored. This study reports a promising and attractive approach to reducing the resistance to drug transport in the carrier matrix, to enhance drug permeability and bioavailability via enhanced concentration-gradient of the driving force for transdermal purposes. This approach simply optimizes and reconstructs the porous channel structure of the carrier matrix, namely, poloxamer 407 (P407-based hydrogel matrix blended with carboxymethyl cellulose sodium (CMCs. Addition of CMCs was found to distinctly improve the porous structure of the P407 matrix. The pore size approximated to normal distribution as CMCs were added and the fraction of pore number was increased by over tenfold. Transdermal studies showed that P407/CMCs saw a significant increase in drug permeability across the skin. This suggests that P407/CMC with improved porous structure exhibits a feasible and promising way for the development of transdermal therapy with high permeability and bioavailability, thereby avoiding or reducing use of any chemical enhancers.

  15. Structural and permeability characterization of biosynthetic PVA hydrogels designed for cell-based therapy.

    Science.gov (United States)

    Nafea, Eman H; Poole-Warren, Laura A; Martens, Penny J

    2014-01-01

    Incorporation of extracellular matrix (ECM) components to synthetic hydrogels has been shown to be the key for successful cell encapsulation devices, by providing a biofunctional microenvironment for the encapsulated cells. However, the influence of adding ECM components into synthetic hydrogels on the permeability as well as the physical and mechanical properties of the hydrogel has had little attention. Therefore, the aim of this study was to investigate the effect of incorporated ECM analogues on the permeability performance of permselective synthetic poly(vinyl alcohol) (PVA) hydrogels in addition to examining the physico-mechanical characteristics. PVA was functionalized with a systematically increased number of methacrylate functional groups per chain (FG/c) to tailor the permselectivity of UV photopolymerized hydrogel network. Heparin and gelatin were successfully incorporated into PVA network at low percentage (1%), and co-hydrogels were characterized for network properties and permeability to bovine serum albumin (BSA) and immunoglobulin G (IgG) proteins. Incorporation of these ECM analogues did not interfere with the base PVA network characteristics, as the controlled hydrogel mesh sizes, swelling and compressive modulii remained unchanged. While the permeation profiles of both BSA and IgG were not affected by the addition of heparin and gelatin as compared with pure PVA, increasing the FG/c from 7 to 20 significantly limited the diffusion of the larger IgG. Consequently, biosynthetic hydrogels composed of PVA with high FG/c and low percent ECM analogues show promise in their ability to be permselective for various biomedical applications.

  16. Study on Storm-Water Management of Grassed Swales and Permeable Pavement Based on SWMM

    Directory of Open Access Journals (Sweden)

    Jianguang Xie

    2017-10-01

    Full Text Available Grassed swales and permeable pavement that have greater permeable underlying surface relative to hard-pressing surface can cooperate with the city pipe network on participating in urban storm flood regulation. This paper took Nanshan village in Jiangsu Province as an example, the storm-water management model (SWMM was used to conceptualize the study area reasonably, and the low-impact development (LID model and the traditional development model were established in the region. Based on the storm-intensity equation, the simulation scene employed the Chicago hydrograph model to synthesize different rainfall scenes with different rainfall repetition periods, and then contrasted the storm-flood-management effect of the two models under the condition of using LID facilities. The results showed that when the rainfall repetition period ranged from 0.33a to 10a (a refers to the rainfall repetition period, the reduction rate of total runoff in the research area that adopted LID ranged from 100% to 27.5%, while the reduction rate of peak flow ranged from 100% to 15.9%, and when the values of unit area were the same, the combined system (permeable pavement + grassed swales worked more efficiently than the sum of the individuals in the reduction of total runoff and peak flow throughout. This research can provide technical support and theoretical basis for urban LID design.

  17. Iron

    Science.gov (United States)

    ... Share: Search the ODS website Submit Search NIH Office of Dietary Supplements Consumer Datos en español Health ... eating a variety of foods, including the following: Lean meat, seafood, and poultry. Iron-fortified breakfast cereals ...

  18. Inverse isotope effect in iron-based superconductor

    International Nuclear Information System (INIS)

    Shirage, Parasharam M.; Kihou, Kunihiro; Miyazawa, Kiichi; Lee, Chul-Ho; Kito, Hijiri; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Tanaka, Yasumoto; Iyo, Akira

    2010-01-01

    We have found that (Ba, K)Fe 2 As 2 superconductor (a transition temperature, T c ∼ 38 K) shows an inverse Iron isotope effect (α Fe = -0.18 ± 0.03, where T c ∼ M -αFe and M is the iron isotope mass), i.e. the sample containing the larger iron mass depicts higher T c . Systematic studies using three types of Fe-isotopes ( 54 Fe, natural Fe and 57 Fe) reveal a clear inverse shift on T c by measurements of temperature dependent magnetization and resistivity. The inverse isotope effect that is the first case in high-T c superconductors strongly suggests that superconducting mechanism of the iron-based system is not explained by conventional BCS theory mediated by phonons.

  19. Studies of anisotropy of iron based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Jason [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    To study the electronic anisotropy in iron based superconductors, the temperature dependent London penetration depth, Δλ (T), have been measured in several compounds, along with the angular dependent upper critical field, Hc2(T). Study was undertaken on single crystals of Ba(Fe1-xCox)2As2 with x=0.108 and x=0.127, in the overdoped range of the doping phase diagram, characterized by notable modulation of the superconducting gap. Heavy ion irradiation with matching field doses of 6 T and 6.5 T respectively, were used to create columnar defects and to study their effect on the temperature Δλ (T). The variation of the low-temperature penetration depth in both pristine and irradiated samples was fitted with a power-law function Δλ (T) = ATn. Irradiation increases the magnitude of the pre-factor A and decreases the exponent n, similar to the effect on the optimally doped samples. This finding supports the universal s± scenario for the whole doping range. Knowing that the s± gap symmetry exists across the superconducting dome for the electron doped systems, we next looked at λ (T), in optimally - doped, SrFe2(As1-xPx)2, x =0.35. Both, as-grown (Tc ~ 25 K) and annealed (Tc ~ 35 K) single crystals of SrFe2(As1-xPx)2 were measured. Annealing decreases the absolute value of the London penetration depth from λ(0) = 300 ± 10 nm in as-grown samples to λ (0) = 275±10 nm. At low temperatures, λ (T) ~ T indicates a superconducting gap with line nodes. Analysis of the full-temperature range superfluid density is consistent with the line nodes, but differs from the simple single-gap d-wave. The observed behavior is very similar to that of BaFe2(As1-xPx)2, showing that isovalently substituted pnictides are inherently different from

  20. Production-log base model for carbonate permeability distribution and steam flood optimization

    Energy Technology Data Exchange (ETDEWEB)

    Ahamed, S.F.; Choudhry, M.A.; Abdulbaqi, J.B. [Kuwait Gulf Oil Co. (Kuwait)

    2008-10-15

    This paper presented a model for the effective management of primary and thermal oil recovery operations in the Wafra Field in Kuwait, where a small huff and puff project was carried out in 1998 to determine if steam injection was a feasible recovery option for the field. The Eocene heavy oil reservoirs of the Wafra Field are carbonate rock admixtures with gypsum and anhydrite. They are the shallowest of the field's productive horizons and exhibit a high degree of fluid flow heterogeneity. The assessment of vertical and lateral permeability variation is a key factor for success of the reservoir development plan. Steam injection began in 2006 in a small scale test (SST) to determine if the innovative technology could produce steam from effluent water and to test the viability of steam injection in carbonate reservoirs. Following the success of the SST, a large scale pilot (LSP) is schedule to start in 2009. It can be used for completion strategies of injectors and producers in steam injection. The model showed that the productivity of the Eocene wells could be correlated with common available logs to develop a log based-permeability model. A series of cross plots for the perforated intervals of high and low productivity wells were constructed to develop a relationship between well productivity and location of log parameters on the plots. A relationship between rock quality, productivity and conventional log parameters was established. It was concluded that the vertical permeability and interwell continuity in the Eocene wells can be used to optimize new well placement for horizontal and vertical infill drilling. The model is also an effective tool to predict the steam injectivity profile to understand the anomalies related to temperature-depth distribution. The model can be used to improve the efficiency of formation heating by optimizing the steam flood process and steam pattern well completion. 16 refs.

  1. Fabrication and Properties of Iron-based Soft Magnetic Composites Coated with NiZnFe2O4

    Directory of Open Access Journals (Sweden)

    WU Shen

    2017-07-01

    Full Text Available This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing the sol-gel method prepared Ni-Zn ferrite particles as insulating compound to coat iron powder, and the influence of NiZnFe2O4 content and molding pressure on the magnetic properties was studied. The morphology, magnetic properties and density of Ni-Zn ferrite insulated compacts were investigated. Scanning electron microscope,line-scan EDX analysis and distribution maps show that the iron particle surface is covered with a thin layer of uniform Ni-Zn ferrites. The existing of the insulating layer can effectively improve the electrical resistivity of soft magnetic composites. Magnetic measurements show that the real part of permeability decreases with the increase of the Ni-Zn ferrite content, and the sample with 3%(mass fraction, the same below Ni-Zn ferrite has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Results show that the addition of NiZnFe2O4 can dramatically decrease the internal magnetic loss, the magnetic loss of coated samples decreases by 83.8% as compared with that of uncoated samples at 100kHz. The density of the Fe-3%NiZnFe2O4 compacts reaches 7.14g/cm3 and the saturation magnetization is 1.47T when the molding pressure is 1000MPa.

  2. Fabrication and properties of iron-based soft magnetic composites coated with parylene via chemical vapor deposition polymerization

    International Nuclear Information System (INIS)

    Wu, Shen; Sun, Aizhi; Lu, Zhenwen; Cheng, Chuan

    2015-01-01

    This paper focuses on novel iron-based soft magnetic composites synthesis utilizing low friction factor parylene C films to coat iron powder via chemical vapor deposition polymerization. The morphology, magnetic properties, density, and chemical stability of parylene insulated iron particles were investigated. The coated parylene insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The thickness of parylene C film is averagely 300 nm according to the results of transmission electron microscopy. Parylene C film uniformly coated the powder surface resulting in reducing the permeability imaginary part, increasing electrical resistivity and increasing the operating frequency of the synthesized magnets. It was shown that the parylene C coated compacts exhibited noticeably higher density compared to the epoxy resin coated compacts at the same pressure, suppress at 800 MPa increased the density by 17.02%. The result of Tafel curves indicated that the resistance of the iron particles to corrosion by NaCl solution is obviously improved after being insulated with parylene C film. - Highlights: • Parylene C uniformly coated the powder, increased the operating frequency of SMCs. • Compared with epoxy coated, the density of SMCs increased by 17.02% at 800 MPa. • The resistance of the iron particles is obviously improved with parylene film insulated

  3. Remediation of persistent organic pollutant-contaminated soil using biosurfactant-enhanced electrokinetics coupled with a zero-valent iron/activated carbon permeable reactive barrier.

    Science.gov (United States)

    Sun, Yuchao; Gao, Ke; Zhang, Yun; Zou, Hua

    2017-12-01

    Zero-valent iron/activated carbon (Fe/C) particles can degrade persistent organic pollutants via micro-electrolysis and therefore, they may be used to develop materials for permeable reactive barriers (PRBs). In this study, surfactant-enhanced electrokinetics (EK) was coupled with a Fe/C-PRB to treat phenanthrene (PHE) and 2,4,6-trichlorophenol (TCP) co-contaminated clay soil. An environment-friendly biosurfactant, rhamnolipid, was selected as the solubility-enhancing agent. Five bench-scale tests were conducted to investigate the performance of EK-PRB on PHE and TCP removal from soil as well as the impact of pH and rhamnolipid concentration. The results show that both PHE and TCP, driven by electro-osmotic flow (EOF), moved toward the cathode and reacted with the Fe/C-PRB. Catholyte acidification and rhamnolipid concentration increase improved the removal efficiencies of PHE and TCP. The highest removal efficiency of PHE in soil column was five times the efficiency of the control group on which only EK was applied (49.89 versus 9.40%). The highest removal efficiency of TCP in soil column was 4.5 times the efficiency of the control group (64.60 versus 14.30%). Desorption and mobility of PHE and TCP improved with the increase of rhamnolipid concentration when this exceeded the critical micelle concentration. This study indicates that the combination of EK and a Fe/C-PRB is efficient and promising for removing persistent organic pollutants (POPs) from contaminated soil with the enhancement of rhamnolipid.

  4. Magnetism and superconductivity in Eu-based iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Zapf, Sina [1. Physikalisches Institut, Universitaet Stuttgart (Germany)

    2015-07-01

    EuFe{sub 2}As{sub 2} is an extraordinary parent compound of the iron pnictides, as it exhibits at low temperatures - additional to the Fe spin density wave - long-range magnetic order of the Eu{sup 2+} local moments. Nevertheless, bulk superconductivity around 30 K can be induced by mechanical pressure or chemical substitution. In this talk we review the remarkable interplay of unconventional superconductivity, itinerant and local magnetism in Eu based iron pnictides. We focus on the appearance of a re-entrant spin glass phase that coexists with superconductivity and an indirect magneto-elastic coupling, enabling the persistent magnetic detwinning by small magnetic fields.

  5. Magnetic properties of iron-based soft magnetic composites with SiO{sub 2} coating obtained by reverse microemulsion method

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Shen [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Sun, Aizhi, E-mail: sunaizhi@126.com [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Lu, Zhenwen; Cheng, Chuan [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Gao, Xuexu [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-05-01

    In this work, iron-based soft magnetic composites coated with the amorphous SiO{sub 2} layer have been fabricated by utilizing tetraethoxysilane in the reverse microemulsion method, and then the effects of addition amount of SiO{sub 2} and annealing temperature on the magnetic properties were investigated. The results show that the surface of iron powders contains a thin amorphous SiO{sub 2} insulation layer, which effectively decreases the magnetic loss of synthesized magnets. The magnetic loss of coated samples decreased by 87.8% as compared with that of uncoated samples at 150 kHz. Magnetic measurements show that the sample with 1.25 wt% SiO{sub 2} has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Also, the annealing treatment increased the initial permeability, the maximum permeability and the magnetic induction and decreased the coercivity with increasing temperature in the range 300–600 °C. The results of the loss separation imply that the annealed SMCs have a higher hysteresis loss coefficient (k{sub 2}) and lower eddy current loss coefficient (k{sub 3}) as compared with the pure iron compacts after the same heat treatment due to the preservation of the SiO{sub 2} layer. - Highlights: • SiO{sub 2} coated the iron powder by reverse microemulsion method, decreased the magnetic loss of SMCs. • 25 wt% is the optimum coating amount to attain the desired permeability. • The influence of annealing temperature on the magnetic performance of the core was discussed. • Compare with the pure iron compacts, the annealed SMCs have lower value of eddy current coefficient.

  6. Iron-based radiochromic systems for UV dosimetry applications

    Science.gov (United States)

    Lee, Hannah J.; Alqathami, Mamdooh; Blencowe, Anton; Ibbott, Geoffrey

    2018-01-01

    Phototherapy treatment using ultraviolet (UV) A and B light sources has long existed as a treatment option for various skin conditions. Quality control for phototherapy treatment recommended by the British Association of Dermatologists and British Photodermatology Group generally focused on instrumentation-based dosimetry measurements. The purpose of this study was to present an alternative, easily prepared dosimeter system for the measurement of UV dose and as a simple quality assurance technique for phototherapy treatments. Five different UVA-sensitive radiochromic dosimeter formulations were investigated and responded with a measurable and visible optical change both in solution and in gel form. Iron(III) reduction reaction formulations were found to be more sensitive to UVA compared to iron(II) oxidation formulations. One iron(III) reduction formulation was found to be especially promising due to its sensitivity to UVA dose, ease of production, and linear response up to a saturation point.

  7. Symptoms-Based Evaluation of Iron Deficiency Anemia in Students ...

    African Journals Online (AJOL)

    Original Research Article. Symptoms-Based ... cravings, 22.33 % (46); and angular stomatitis 18.97 % (39). ... [6]. Pregnancy fallouts in an overall surplus iron constraint is about 1000 mg [7]. .... Evaluation of the Health-related Quality of Life of.

  8. Iron-based Nanocomposite Synthesised by Microwave Plasma Decomposition of Iron Pentacarbonyl

    Czech Academy of Sciences Publication Activity Database

    David, Bohumil; Pizúrová, Naděžda; Schneeweiss, Oldřich; Hoder, T.; Kudrle, V.; Janča, J.

    2007-01-01

    Roč. 263, - (2007), s. 147-152 ISSN 1012-0386. [Diffusion and Thermodynamics of Materials /IX/. Brno, 13.09.2006-15.09.2006] R&D Projects: GA ČR GA202/04/0221 Institutional research plan: CEZ:AV0Z20410507 Keywords : iron-based nanopowder * synthesis * microwave plasma method Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.483, year: 2005 http://www.scientific.net/3-908451-35-3/3.html

  9. Crustal permeability

    Science.gov (United States)

    Gleeson, Tom; Ingebritsen, Steven E.

    2016-01-01

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

  10. Iron-based superconductors via soft chemistry

    International Nuclear Information System (INIS)

    Friederichs, Gina Maya

    2015-01-01

    This thesis provides new soft chemistry approaches to Fe-based superconductors. Mild syntheses were demonstrated to be able to overcome difficulties, occurring in conventional synthesis and to enable the access to new metastable phases. A solvent-based metathesis reaction led to β-FeSe exclusively. Contrary to solid state syntheses, the formation of hexagonal α-FeSe could be avoided under mild conditions. The deintercalation of interstitial Fe (by formation of Fe 3 O 4 ) could be proven by low temperature O 2 -annealing of Fe 1+x Te 1-y Se y . By using redox (de)intercalations K 1-x Fe 2-y Se 2 , metastable Na 1-x Fe 2-y As 2 and Na 1-x ((Fe 1-y Co y ) 1-z As) 2 could successfully be obtained at room temperature. The mild synthesis conditions led to compounds like FeSe and K 1-x Fe 2-y Se 2 which exhibited different physical properties than found by conventional high temperature methods. In general, the developed (de)intercalation reactions represent a new, universally applicable tool in order to manipulate the structure along with the properties of Fe-based superconductors. The basic structural features of the characteristic FeX 4/4 tetrahedral layers, however, are preserved. Soft chemistry syntheses have been shown to allow the formation of a variety of phases, like Na 1-x Fe 2-y As 2 , Na 1-x ((Fe 1-y Co y ) 1-z As) 2 and K 1-x Fe 2-y Se 2 . Hence, especially low temperature approaches may enable the realization of complex stacking sequences, potentially leading to the fulfillment of the greatest goal in the research of superconductors - room temperature superconductivity.

  11. Iron-Based Superconductors as Odd-Parity Superconductors

    Directory of Open Access Journals (Sweden)

    Jiangping Hu

    2013-07-01

    Full Text Available Parity is a fundamental quantum number used to classify a state of matter. Materials rarely possess ground states with odd parity. We show that the superconducting state in iron-based superconductors is classified as an odd-parity s-wave spin-singlet pairing state in a single trilayer FeAs/Se, the building block of the materials. In a low-energy effective model constructed on the Fe square bipartite lattice, the superconducting order parameter in this state is a combination of an s-wave normal pairing between two sublattices and an s-wave η pairing within the sublattices. The state has a fingerprint with a real-space sign inversion between the top and bottom As/Se layers. The results suggest that iron-based superconductors are a new quantum state of matter, and the measurement of the odd parity can help to establish high-temperature superconducting mechanisms.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-01

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

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  14. Synthesis and characterization of iron based nanoparticles for novel applications

    Science.gov (United States)

    Khurshid, Hafsa

    The work in this thesis has been focused on the fabrication and characterization of iron based nanoparticles with controlled size and morphology with the aim: (i) to investigate their properties for potential applications in MICR toners and biomedical field and (ii) to study finite size effects on the magnetic properties of the nanoparticles. For the biomedical applications, core/shell structured iron/iron-oxide and hollow shell nanoparticles were synthesized by thermal decomposition of iron organometallic compounds [Fe(CO)5] at high temperature. Core/shell structured iron/iron-oxide nanoparticles have been prepared in the presence of oleic acid and oleylamine. Particle size and composition was controlled by varying the reaction parameters during synthesis. The as-made particles are hydrophobic and not dispersible in water. Water dispersibility was achieved by ligand exchange a with double hydrophilic diblock copolymer. Relaxometery measurements of the transverse relaxation time T2 of the nanoparticles solution at 3 Tesla confirm that the core/shell nanoparticles are an excellent MRI contrast agent using T2 weighted imaging sequences. In comparison to conventionally used iron oxide nanoparticles, iron/iron-oxide core/shell nanoparticles offer four times stronger T2 shortening effect at comparable core size due to their higher magnetization. The magnetic properties were studied as a function of particle size, composition and morphology. Hollow nanostructures are composed of randomly oriented grains arranged together to make a shell layer and make an interesting class of materials. The hollow morphology can be used as an extra degree of freedom to control the magnetic properties. Owing to their hollow morphology, they can be used for the targeted drug delivery applications by filling the drug inside their cavity. For the magnetic toners applications, particles were synthesized by chemically reducing iron salt using sodium borohydride and then coated with polyethylene

  15. Spin excitations in hole-overdoped iron-based superconductors.

    Science.gov (United States)

    Horigane, K; Kihou, K; Fujita, K; Kajimoto, R; Ikeuchi, K; Ji, S; Akimitsu, J; Lee, C H

    2016-09-12

    Understanding the overall features of magnetic excitation is essential for clarifying the mechanism of Cooper pair formation in iron-based superconductors. In particular, clarifying the relationship between magnetism and superconductivity is a central challenge because magnetism may play a key role in their exotic superconductivity. BaFe2As2 is one of ideal systems for such investigation because its superconductivity can be induced in several ways, allowing a comparative examination. Here we report a study on the spin fluctuations of the hole-overdoped iron-based superconductors Ba1-xKxFe2As2 (x = 0.5 and 1.0; Tc = 36 K and 3.4 K, respectively) over the entire Brillouin zone using inelastic neutron scattering. We find that their spin spectra consist of spin wave and chimney-like dispersions. The chimney-like dispersion can be attributed to the itinerant character of magnetism. The band width of the spin wave-like dispersion is almost constant from the non-doped to optimum-doped region, which is followed by a large reduction in the overdoped region. This suggests that the superconductivity is suppressed by the reduction of magnetic exchange couplings, indicating a strong relationship between magnetism and superconductivity in iron-based superconductors.

  16. Optical and magnetization studies on europium based iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Zapf, Sina Maria Ute

    2015-07-01

    The investigations carried out in the framework of this thesis mainly concentrate on europium based iron pnictides. These are a peculiar member of the 122 family as they develop at low temperatures (∝20K) an additional magnetic order of the local rare earth moments. Therefore, europium based iron pnictides provide a unique platform to study the interplay of structural, magnetic and electronic effects in high-temperature superconductors. For this challenging purpose, we have employed SQUID magnetometry and Fourier-transform infrared spectroscopy on EuFe{sub 2}(As{sub 1-x}P{sub x}){sub 2} single crystals. By systematic studies of the in- and out-of-plane magnetic properties of a series of single crystals, we derived the complex magnetic phase diagram of europium based iron pnictides, which contains an A-type antiferromagnetic and a re-entrant spin glass phase. Furthermore, we have investigated the magneto-optical properties of EuFe{sub 2}As{sub 2}, revealing a much more complex magnetic detwinning process than expected. These studies demonstrate a remarkable interdependence between magnetic, electronic and structural effects that might be very important to understand the unconventional superconductivity in these fascinating materials.

  17. Optical and magnetization studies on europium based iron pnictides

    International Nuclear Information System (INIS)

    Zapf, Sina Maria Ute

    2015-01-01

    The investigations carried out in the framework of this thesis mainly concentrate on europium based iron pnictides. These are a peculiar member of the 122 family as they develop at low temperatures (∝20K) an additional magnetic order of the local rare earth moments. Therefore, europium based iron pnictides provide a unique platform to study the interplay of structural, magnetic and electronic effects in high-temperature superconductors. For this challenging purpose, we have employed SQUID magnetometry and Fourier-transform infrared spectroscopy on EuFe 2 (As 1-x P x ) 2 single crystals. By systematic studies of the in- and out-of-plane magnetic properties of a series of single crystals, we derived the complex magnetic phase diagram of europium based iron pnictides, which contains an A-type antiferromagnetic and a re-entrant spin glass phase. Furthermore, we have investigated the magneto-optical properties of EuFe 2 As 2 , revealing a much more complex magnetic detwinning process than expected. These studies demonstrate a remarkable interdependence between magnetic, electronic and structural effects that might be very important to understand the unconventional superconductivity in these fascinating materials.

  18. Regeneration of Iron-based Adsorptive Media Used for Removing Arsenic from Groundwater

    Science.gov (United States)

    The journal article will describe batch and column regeneration tests and results that were conducted on six exhausted iron media products to determine whether an iron based media can be successfully regenerated and reused.

  19. Notional Permeability

    NARCIS (Netherlands)

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

    2012-01-01

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

  20. Iron oxide nanotubes synthesized via template-based electrodeposition

    Science.gov (United States)

    Lim, Jin-Hee; Min, Seong-Gi; Malkinski, Leszek; Wiley, John B.

    2014-04-01

    Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition. In the case of magnetite nanotubes, which consist of slightly larger nanoparticles, magnetization curves show ferromagnetism with weak coercivity at room temperature, while FC-ZFC curves exhibit the Verwey transition at 125 K.Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition

  1. A Discovery-Based Experiment Illustrating How Iron Metal Is Used to Remediate Contaminated Groundwater

    Science.gov (United States)

    Balko, Barbara A.; Tratnyek, Paul G.

    2001-12-01

    In this article, we describe an experiment for undergraduate general chemistry in which students investigate the chemistry behind iron-permeable reactive barriers (iron PRBs), a new technology that is widely used to remediate contaminated groundwater. Contaminant remediation involving iron PRBs is a redox process: the iron metal undergoes oxidative dissolution while the contaminant is reduced. The reaction is complicated, however, by the fact that it involves a surface that changes owing to the development of a layer of rust (iron oxide) on the iron. In this experiment, students examine the iron PRB-contaminant reaction by characterizing the kinetics of the degradation of a dye (the model contaminant) in the presence of granular iron under various experimental conditions. Students can be asked to design their own experiments to investigate aspects of the degradation reaction that are of particular interest to them. The material covered in the lab includes oxidation-reduction reactions, pseudo first-order kinetics, spectrophotometry, and the application of chemistry to solving environmental problems. The experiment can also be used as a vehicle to introduce more advanced topics in chemistry such as heterogeneous reactions, corrosion, passive film growth, and mass transport.

  2. Promising iron oxide-based magnetic nanoparticles in biomedical engineering.

    Science.gov (United States)

    Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Vo, Toi Van; Lee, Beom-Jin

    2012-12-01

    For the past few decades biomedical engineering has imprinted its significant impact on the map of science through its wide applications on many other fields. An important example obviously proving this fact is the versatile application of magnetic nanoparticles in theranostics. Due to preferable properties such as biocompatibility, non-toxicity compared to other metal derivations, iron oxide-based magnetic nanoparticles was chosen to be addressed in this review. Aim of this review is to give the readers a whole working window of these magnetic nanoparticles in the current context of science. Thus, preparation of magnetic iron oxide nanoparticles with the so-far techniques, methods of characterizing the nanoparticles as well as their most recent biomedical applications will be stated.

  3. Microfluidic-based Broadband Measurements of Fluid Permittivity and Permeability to 100 GHz

    Science.gov (United States)

    Little, Charles A. E.

    This dissertation concerns the development of unique microfluidic microwave devices and associated microwave calibrations to quantitatively extract the broadband permittivity and permeability of fluids between 100 kHz and 110 GHz. The devices presented here consist of SU-8- and PDMS-based microfluidic channels integrated lithographically with coplanar waveguides (CPWs), measured via an external vector network analyzer (VNA). By applying our hybrid set of microwave calibrations to the raw data we extract distributed circuit parameters, representative of the electromagnetic response of the microfluidic channel. We then correlate these parameters to the permittivity and permeability of the fluid within the channels. We are primarily focused on developing devices, calibrations, and analyses to characterize various chemical and biological systems. The small fluid volumes and overall scale of our devices lends the technique to point-of-care blood and cell analysis, as well as to the analysis of high-value chemicals. Broadband microwave microfluidics is sensitive to three primary categories of phenomena: Ionic, dipolar, and magnetic resonances. All three can occur in complex fluids such as blood, proteins and particle suspensions. In order to make quantitative measurements, we need to be able to model and separate all three types of responses. Here we first measure saline solutions (NaCl and water) as an ideal system to better understanding both the ionic and dipolar response. Specifically, we are targeting the electrical double-layer (EDL) response, an ionic effect, which dominates over the intrinsic fluid response at lower frequencies. We have found that the EDL response for saline obeys a strict Debye-type relaxation model, the frequency response of which is dependent solely on the conductivity of the solution. To develop a better understanding of the magnetic response, we first measure magnetic nanoparticles; showing it is possible to detect the magnetic resonances of

  4. Potential of Phytase-Mediated Iron Release from Cereal-Based Foods: A Quantitative View

    Science.gov (United States)

    Nielsen, Anne V. F.; Tetens, Inge; Meyer, Anne S.

    2013-01-01

    The major part of iron present in plant foods such as cereals is largely unavailable for direct absorption in humans due to complexation with the negatively charged phosphate groups of phytate (myo-inositol (1,2,3,4,5,6)-hexakisphosphate). Human biology has not evolved an efficient mechanism to naturally release iron from iron phytate complexes. This narrative review will evaluate the quantitative significance of phytase-catalysed iron release from cereal foods. In vivo studies have shown how addition of microbially derived phytases to cereal-based foods has produced increased iron absorption via enzyme-catalysed dephosphorylation of phytate, indicating the potential of this strategy for preventing and treating iron deficiency anaemia. Despite the immense promise of this strategy and the prevalence of iron deficiency worldwide, the number of human studies elucidating the significance of phytase-mediated improvements in iron absorption and ultimately in iron status in particularly vulnerable groups is still low. A more detailed understanding of (1) the uptake mechanism for iron released from partially dephosphorylated phytate chelates, (2) the affinity of microbially derived phytases towards insoluble iron phytate complexes, and (3) the extent of phytate dephosphorylation required for iron release from inositol phosphates is warranted. Phytase-mediated iron release can improve iron absorption from plant foods. There is a need for development of innovative strategies to obtain better effects. PMID:23917170

  5. Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy

    Science.gov (United States)

    Grathoff, Georg H.; Peltz, Markus; Enzmann, Frieder; Kaufhold, Stephan

    2016-07-01

    The goal of this study is to better understand the porosity and permeability in shales to improve modelling fluid and gas flow related to shale diagenesis. Two samples (WIC and HAD) were investigated, both mid-Jurassic organic-rich Posidonia shales from Hils area, central Germany of different maturity (WIC R0 0.53 % and HAD R0 1.45 %). The method for image collection was focused ion beam (FIB) microscopy coupled with scanning electron microscopy (SEM). For image and data analysis Avizo and GeoDict was used. Porosity was calculated from segmented 3-D FIB based images and permeability was simulated by a Navier Stokes-Brinkman solver in the segmented images. Results show that the quantity and distribution of pore clusters and pores (≥ 40 nm) are similar. The largest pores are located within carbonates and clay minerals, whereas the smallest pores are within the matured organic matter. Orientation of the pores calculated as pore paths showed minor directional differences between the samples. Both samples have no continuous connectivity of pore clusters along the axes in the x, y, and z direction on the scale of 10 to 20 of micrometer, but do show connectivity on the micrometer scale. The volume of organic matter in the studied volume is representative of the total organic carbon (TOC) in the samples. Organic matter does show axis connectivity in the x, y, and z directions. With increasing maturity the porosity in organic matter increases from close to 0 to more than 5 %. These pores are small and in the large organic particles have little connection to the mineral matrix. Continuous pore size distributions are compared with mercury intrusion porosimetry (MIP) data. Differences between both methods are caused by resolution limits of the FIB-SEM and by the development of small pores during the maturation of the organic matter. Calculations show no permeability when only considering visible pores due to the lack of axis connectivity. Adding the organic matter with a

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

    Science.gov (United States)

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

    2015-01-01

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

  7. Permeable pavement study (Edison)

    Data.gov (United States)

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

  8. Integrated evaluation of the performance of a more than seven year old permeable reactive barrier at a site contaminated with chlorinated aliphatic hydrocarbons (CAHs)

    DEFF Research Database (Denmark)

    Muchitsch, Nanna; Nooten, Thomas Van; Bastiaens, Leen

    2011-01-01

    An important issue of concern for permeable reactive iron barriers is the long-term efficiency of the barriers due to the long operational periods required. Mineral precipitation resulting from the anaerobic corrosion of the iron filings and bacteria present in the barrier may play an important...... performed equally well as virgin granular iron of the same type based on determined degradation rates despite that parts of the cored iron material were covered by mineral precipitates (especially iron sulfides, carbonate green rust and aragonite). The PCR analysis performed on the iron core samples...

  9. Determination of water-lock critical value of low-permeability sandstones based on digital core

    Directory of Open Access Journals (Sweden)

    Honglin Zhu

    2016-05-01

    Full Text Available Research and development of water lock inhibiting measures is very crucial in verifying the link mechanism between the internal factors of water lock and its extent of damage. Based on conventional water-lock physics experiments, however, only the consequence of macro water lock damage can be investigated, while the microscopic mechanism cannot be studied. In this paper, 3D digital cores of low-permeability sandstones were prepared by means of high-resolution micro-CT scan, and their equivalent pore network model was built as well. Virtual “imbibition” experiments controlled by capillary force were carried out by using pore-scale flow simulation. Then the link mechanism between the microscopic internal factors (e.g. wettability, water saturation and pore–throat structure parameters and the water-lock damage degree was discussed. It is shown that the damage degree of water lock reduces gradually as the wettability transits from water wet to gas wet. Therefore, the water lock damage can be reduced effectively and gas-well productivity can be improved so long as the capillary environment is changed from strong water wettability to weak gas wettability. The more different the initial water saturation is from the irreducible water saturation, the more serious the water lock damage is. The damage degree of water lock is in a negative correlation with the coordinate number, but a positive correlation with the pore–throat ratio. Based on the existing research results, water lock tends to form in the formations composed of medium-sized throats. It is concluded that there is a critical throat radius, at which the water lock is the most serious.

  10. Using electron irradiation to probe iron-based superconductors

    Science.gov (United States)

    Cho, Kyuil; Kończykowski, M.; Teknowijoyo, S.; Tanatar, M. A.; Prozorov, R.

    2018-06-01

    High-energy electron irradiation at low temperatures is an efficient and controlled way to create vacancy–interstitial Frenkel pairs in a crystal lattice, thereby inducing nonmagnetic point-like scattering centers. In combination with London penetration depth and resistivity measurements, the electron irradiation was used as a phase-sensitive probe to study the superconducting order parameter in iron-based superconductors (FeSCs), lending strong support to sign-changing s ± pairing. Here, we review the key results of the effect of electron irradiation in FeSCs.

  11. Potential of phytase-mediated iron release from cereal-based foods: a quantitative view

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Tetens, Inge; Meyer, Anne S.

    2013-01-01

    The major part of iron present in plant foods such as cereals is largely unavailable for direct absorption in humans due to complexation with the negatively charged phosphate groups of phytate (myo-inositol (1,2,3,4,5,6)-hexakisphosphate). Human biology has not evolved an efficient mechanism...... to naturally release iron from iron phytate complexes. This narrative review will evaluate the quantitative significance of phytase-catalysed iron release from cereal foods. In vivo studies have shown how addition of microbially derived phytases to cereal-based foods has produced increased iron absorption via...... phytate complexes, and (3) the extent of phytate dephosphorylation required for iron release from inositol phosphates is warranted. Phytase-mediated iron release can improve iron absorption from plant foods. There is a need for development of innovative strategies to obtain better effects....

  12. Iron oxide-based nanomagnets in nanomedicine: fabrication and applications

    Directory of Open Access Journals (Sweden)

    Meng Meng Lin

    2010-02-01

    Full Text Available Iron oxide-based nanomagnets have attracted a great deal of attention in nanomedicine over the past decade. Down to the nanoscale, superparamagnetic iron oxide nanoparticles can only be magnetized in the presence of an external magnetic field, which makes them capable of forming stable colloids in a physio-biological medium. Their superparamagnetic property, together with other intrinsic properties, such as low cytotoxicity, colloidal stability, and bioactive molecule conjugation capability, makes such nanomagnets ideal in both in-vitro and in-vivo biomedical applications. In this review, a chemical, physical, and biological synthetic approach to prepare iron oxide-based nanomagnets with different physicochemical properties was illustrated and compared. The growing interest in iron oxide-based nanomagnets with multifunctionalities was explored in cancer diagnostics and treatment, focusing on their combined roles in a magnetic resonance contrast agent, hyperthermia, and magnetic force assisted drug delivery. Iron oxides as magnetic carriers in gene therapy were reviewed with a focus on the sophisticated design and construction of magnetic vectors. Finally, the iron oxide-based nanomagnet also represents a very promising tool in particle/cell interfacing in controlling cellular functionalities, such as adhesion, proliferation, differentiation, and cell patterning, in stem cell therapy and tissue engineering applications. Meng Meng Lin received a BSc in biotechnology at the University of Hong Kong, China in 2004 and an MSc in biomedical nanotechnology at Newcastle University, UK, in 2005. She is currently working toward her PhD at the Institute of Science and Technology in Medicine, Keele University, UK. She was a visiting student at the Royal Institute of Technology, Sweden, in 2006. Her research interests include nanoparticles preparation, cell/nanomaterials interface, and cancer-oriented drug delivery. Hyung-Hwan Kim received an MSc degree in

  13. A topology optimization method based on the level set method for the design of negative permeability dielectric metamaterials

    DEFF Research Database (Denmark)

    Otomori, Masaki; Yamada, Takayuki; Izui, Kazuhiro

    2012-01-01

    This paper presents a level set-based topology optimization method for the design of negative permeability dielectric metamaterials. Metamaterials are artificial materials that display extraordinary physical properties that are unavailable with natural materials. The aim of the formulated...... optimization problem is to find optimized layouts of a dielectric material that achieve negative permeability. The presence of grayscale areas in the optimized configurations critically affects the performance of metamaterials, positively as well as negatively, but configurations that contain grayscale areas...... are highly impractical from an engineering and manufacturing point of view. Therefore, a topology optimization method that can obtain clear optimized configurations is desirable. Here, a level set-based topology optimization method incorporating a fictitious interface energy is applied to a negative...

  14. Carbon-based building blocks for alcohol dehydration membranes with disorder-enhanced water permeability

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Etmimi, H.; Mallon, P.E.

    2017-01-01

    Graphene oxide (GO) thin films have demonstrated outstanding water permeability and excellent selectivity towards organic molecules and inorganic salts, unlocking a new exciting direction in the development of nanofiltration, desalination and pervaporation membranes. However, there are still high......-HAL membranes promising devices for alcohol dehydration technologies....

  15. Leak-Based Method for the Measurement of Air Permeability of Papers

    Directory of Open Access Journals (Sweden)

    Colard Stéphane

    2016-01-01

    Full Text Available The air permeability of cigarette paper is currently assessed according to the international standard ISO 2965 by applying a constant pressure difference of 1 kPa between the two faces of a sample and by measuring the corresponding airflow.

  16. Hybrid crystals of cuprates and iron-based superconductors

    Science.gov (United States)

    Xia, Dai; Cong-Cong, Le; Xian-Xin, Wu; Jiang-Ping, Hu

    2016-07-01

    We propose two possible new compounds, Ba2CuO2Fe2As2 and K2CuO2Fe2Se2, which hybridize the building blocks of two high temperature superconductors, cuprates and iron-based superconductors. These compounds consist of square CuO2 layers and antifluorite-type Fe2 X 2 (X = As, Se) layers separated by Ba/K. The calculations of binding energies and phonon spectra indicate that they are dynamically stable, which ensures that they may be experimentally synthesized. The Fermi surfaces and electronic structures of the two compounds inherit the characteristics of both cuprates and iron-based superconductors. These compounds can be superconductors with intriguing physical properties to help to determine the pairing mechanisms of high T c superconductivity. Project supported by the National Basic Research Program of China (Grant No. 2015CB921300), the National Natural Science Foundation of China (Grant Nos. 1190020 and 11334012), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07000000).

  17. Comparative metatranscriptomics identifies molecular bases for the physiological responses of phytoplankton to varying iron availability.

    Science.gov (United States)

    Marchetti, Adrian; Schruth, David M; Durkin, Colleen A; Parker, Micaela S; Kodner, Robin B; Berthiaume, Chris T; Morales, Rhonda; Allen, Andrew E; Armbrust, E Virginia

    2012-02-07

    In vast expanses of the oceans, growth of large phytoplankton such as diatoms is limited by iron availability. Diatoms respond almost immediately to the delivery of iron and rapidly compose the majority of phytoplankton biomass. The molecular bases underlying the subsistence of diatoms in iron-poor waters and the plankton community dynamics that follow iron resupply remain largely unknown. Here we use comparative metatranscriptomics to identify changes in gene expression associated with iron-stimulated growth of diatoms and other eukaryotic plankton. A microcosm iron-enrichment experiment using mixed-layer waters from the northeastern Pacific Ocean resulted in increased proportions of diatom transcripts and reduced proportions of transcripts from most other taxa within 98 h after iron addition. Hundreds of diatom genes were differentially expressed in the iron-enriched community compared with the iron-limited community; transcripts of diatom genes required for synthesis of photosynthesis and chlorophyll components, nitrate assimilation and the urea cycle, and synthesis of carbohydrate storage compounds were significantly overrepresented. Transcripts of genes encoding rhodopsins in eukaryotic phytoplankton were significantly underrepresented following iron enrichment, suggesting rhodopsins help cells cope with low-iron conditions. Oceanic diatoms appear to display a distinctive transcriptional response to iron enrichment that allows chemical reduction of available nitrogen and carbon sources along with a continued dependence on iron-free photosynthetic proteins rather than substituting for iron-containing functional equivalents present within their gene repertoire. This ability of diatoms to divert their newly acquired iron toward nitrate assimilation may underlie why diatoms consistently dominate iron enrichments in high-nitrate, low-chlorophyll regions.

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

    Directory of Open Access Journals (Sweden)

    Ayşegül Güneş Seferoğlu

    2018-01-01

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

  19. EDITORIAL: The electromagnetic properties of iron-based superconductors The electromagnetic properties of iron-based superconductors

    Science.gov (United States)

    Prozorov, Ruslan; Gurevich, Alex; Luke, Graeme

    2010-05-01

    Iron-based superconductors, discovered just a few years ago, are members of a diverse family of pnictides and chalcogenides which may potentially contain hundreds of superconducting compounds. The unconventional, multiband superconductivity in these materials most likely emerges from the quintessential magnetic Fe ions. Along with many similarities to the high-Tc cuprates, the proximity of antiferromagnetism to superconductivity in these semi-metallic materials has attracted much attention. The massive effort aimed at understanding superconductivity in the high-Tc cuprates has stimulated the development of numerous state-of-the-art experimental techniques, improved crystal growth methods and a variety of new theoretical insights. These tools and models were already available and readily applied to the new iron-based superconductors for which lots of high quality new results are being reported literally every day. The current special section represents only a snapshot of these extensive studies performed in the second half of 2009, less than two years after the discovery of 26 K superconductivity in the LaFeAsO compound. The range of various experiments is impressive and this issue is mostly focused on the electromagnetic properties of these iron-based materials. The electromagnetic response is sensitive to the microscopic electronic behavior and therefore can be used to probe the mechanism of superconductivity. On the other hand, it is the electromagnetic response that determines many possible applications of these superconductors, particularly given their extremely high upper critical fields. At this point it is already quite clear that the iron-based superconductors cannot unambiguously fit into any known type of superconductor class and have been placed in one of their own. The metallic ground state of the parent compounds is different from the insulating state of the cuprates and generally exhibits a lower electromagnetic anisotropy. However, similar to the

  20. Experimental research on the characteristics of softening and melting of iron ores as significant factor of influence on gas permeability of blast furnace charge

    International Nuclear Information System (INIS)

    Branescu, E; Blajan, A O; Constantin, N

    2015-01-01

    It is widely accepted as a cohesive zone is directly influenced by softening and melting properties of iron ores, preparations (crowded, pellets, which represents about 90%, of the loads with metal furnace intake), or uncooked (raw ores ranked). Important results can be obtained through the study of behavior of ferrous materials at temperatures above 1000 ° C. Starting from research methods presented in the literature, this paper presents itself in carrying out their own laboratory experiments, conducted with the aim of analysing the softening and melting properties of sinter iron cores. (paper)

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. Complex permeability and core loss of soft magnetic Fe-based nanocrystalline powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Füzerová, Jana, E-mail: jana.fuzerova@tuke.sk [Faculty of Mechanical Engineering, Technical University, Letná 1, 042 00 Košice (Slovakia); Füzer, Ján; Kollár, Peter [Institute of Physics, P.J. Šafárik University, Park Angelinum 9, 040 23 Košice (Slovakia); Bureš, Radovan; Fáberová, Mária [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice (Slovakia)

    2013-11-15

    Rapidly quenched ribbons of Fe{sub 73}Cu{sub 1}Nb{sub 3}Si{sub 16}B{sub 7} were ball milled and cryomilled to get powder and warm consolidated to get bulk compacts. The data presented here are relative to different experimental procedures, one corresponding to milling at room temperature (sample R1) and the other corresponding to cryomilling at temperature of liquid nitrogen (sample L1). It was found that the properties of the initial powder influenced the density, the electrical resistivity and electromagnetic properties of the resulting bulk alloys. Permeability and core loss are structure sensitive and depend on factors such as powder size and shape, porosity, purity, and internal stress. Permeability spectra of sample R1 decreases with increasing the frequency and its values are larger than that for sample L1 at low frequencies. On the other hand the permeability of sample L1 remains steady up to 1 kHz and at certain frequency is larger than that for sample R1. Also there are different frequency dependences of the imaginary parts of permeability and loss factor, respectively. The cryomilling of the amorphous ribbon positively influences on the AC magnetic properties at higher frequencies (above 100 Hz) of resulting bulk sample. - Highlights: • We prepared two different amorphous powder vitroperm samples. • We have examined changes in the properties of the bulk samples prepared by compaction. • It was found that properties of the initial powder influence the density, the electrical resistivity and electromagnetic properties of the resulting bulk alloys.

  3. Retention behavior of flavonoids on immobilized artificial membrane chromatography and correlation with cell-based permeability.

    Science.gov (United States)

    Tsopelas, Fotios; Tsagkrasouli, Maria; Poursanidis, Pavlos; Pitsaki, Maria; Vasios, George; Danias, Panagiotis; Panderi, Irene; Tsantili-Kakoulidou, Anna; Giaginis, Constantinos

    2018-03-01

    The aim of the study was to investigate the immobilized artificial membrane (IAM) retention mechanism for a set of flavonoids and to evaluate the potential of IAM chromatography to model Caco-2 permeability. For this purpose, the retention behavior of 41 flavonoid analogs on two IAM stationary phases, IAM.PC.MG and IAM.PC.DD2, was investigated. Correlations between retention factors, logk w(IAM) and octanol-water partitioning (logP) were established and the role of hydroxyl groups of flavonoids to the underlying retention mechanism was explored. IAM retention and logP values were used to establish sound linear models with Caco-2 permeability (logP app ) taken from the literature. Both stepwise regression and multivariate analysis confirmed the contribution of hydrogen bond descriptors, as additional parameters in the either logk w(IAM) or logP models. Retention factors on both IAM stationary phases showed comparable performance with n-octanol-water partitioning towards Caco-2 permeability. Copyright © 2017 John Wiley & Sons, Ltd.

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

    Science.gov (United States)

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

    2007-01-01

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

  5. Prediction of Placental Barrier Permeability: A Model Based on Partial Least Squares Variable Selection Procedure

    Directory of Open Access Journals (Sweden)

    Yong-Hong Zhang

    2015-05-01

    Full Text Available Assessing the human placental barrier permeability of drugs is very important to guarantee drug safety during pregnancy. Quantitative structure–activity relationship (QSAR method was used as an effective assessing tool for the placental transfer study of drugs, while in vitro human placental perfusion is the most widely used method. In this study, the partial least squares (PLS variable selection and modeling procedure was used to pick out optimal descriptors from a pool of 620 descriptors of 65 compounds and to simultaneously develop a QSAR model between the descriptors and the placental barrier permeability expressed by the clearance indices (CI. The model was subjected to internal validation by cross-validation and y-randomization and to external validation by predicting CI values of 19 compounds. It was shown that the model developed is robust and has a good predictive potential (r2 = 0.9064, RMSE = 0.09, q2 = 0.7323, rp2 = 0.7656, RMSP = 0.14. The mechanistic interpretation of the final model was given by the high variable importance in projection values of descriptors. Using PLS procedure, we can rapidly and effectively select optimal descriptors and thus construct a model with good stability and predictability. This analysis can provide an effective tool for the high-throughput screening of the placental barrier permeability of drugs.

  6. Beyond liposomes: Recent advances on lipid based nanostructures for poorly soluble/poorly permeable drug delivery.

    Science.gov (United States)

    Teixeira, M C; Carbone, C; Souto, E B

    2017-10-01

    Solid lipid nanoparticle (SLN), nanostructured lipid carriers (NLC) and hybrid nanoparticles, have gained increasing interest as drug delivery systems because of their potential to load and release drugs from the Biopharmaceutical classification system (BCS) of class II (low solubility and high permeability) and of class IV (low solubility and low permeability). Lipid properties (e.g. high solubilizing potential, biocompatibility, biotolerability, biodegradability and distinct route of absorption) contribute for the improvement of the bioavailability of these drugs for a set of administration routes. Their interest continues to grow, as translated by the number of patents being field worldwide. This paper discusses the recent advances on the use of SLN, NLC and lipid-polymer hybrid nanoparticles for the loading of lipophilic, poorly water-soluble and poorly permeable drugs, being developed for oral, topical, parenteral and ocular administration, also discussing the industrial applications of these systems. A review of the patents filled between 2014 and 2017, concerning the original inventions of lipid nanocarriers, is also provided. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Corrosion of iron-base alloys by lithium

    International Nuclear Information System (INIS)

    Selle, J.E.

    1976-01-01

    A review of corrosion mechanisms operating in lithium-iron-base alloy systems is presented along with data obtained with thermal-convection loops of niobium-stabilized 2 1 / 4 percent Cr-1 percent Mo steel and types 304L and 321 stainless steels. A corrosion rate of 2.3 μm/year (0.09 mil/year) was obtained on the 2 1 / 4 percent Cr-1 percent Mo steel at 600 0 C. Considerably more mass transport of alloying constituents and a maximum corrosion rate of about 14 μm/year (0.55 mil/year) was obtained with the austenitic stainless steels. Results of metallography, x-ray fluorescence analysis, scanning electron microscopy, and weight-change data are presented and discussed

  8. Salt Fog Testing Iron-Based Amorphous Alloys

    International Nuclear Information System (INIS)

    Rebak, Raul B.; Aprigliano, Louis F.; Day, S. Daniel; Farmer, Joseph C.

    2007-01-01

    Iron-based amorphous alloys are hard and highly corrosion resistant, which make them desirable for salt water and other applications. These alloys can be produced as powder and can be deposited as coatings on any surface that needs to be protected from the environment. It was of interest to examine the behavior of these amorphous alloys in the standard salt-fog testing ASTM B 117. Three different amorphous coating compositions were deposited on 316L SS coupons and exposed for many cycles of the salt fog test. Other common engineering alloys such as 1018 carbon steel, 316L SS and Hastelloy C-22 were also tested together with the amorphous coatings. Results show that amorphous coatings are resistant to rusting in salt fog. Partial devitrification may be responsible for isolated rust spots in one of the coatings. (authors)

  9. Definition of Iron Deficiency Based on the Gold Standard of Bone Marrow Iron Staining in Heart Failure Patients.

    Science.gov (United States)

    Grote Beverborg, Niels; Klip, IJsbrand T; Meijers, Wouter C; Voors, Adriaan A; Vegter, Eline L; van der Wal, Haye H; Swinkels, Dorine W; van Pelt, Joost; Mulder, Andre B; Bulstra, Sjoerd K; Vellenga, Edo; Mariani, Massimo A; de Boer, Rudolf A; van Veldhuisen, Dirk J; van der Meer, Peter

    2018-02-01

    The most commonly used definition of iron deficiency (ID; ferritin the biomarker-based definition of ID in HF, using bone marrow iron staining as the gold standard. Second, we aimed to assess the prognostic value of the optimized definition. Bone marrow aspiration with iron staining was performed in 42 patients with HF and a reduced left ventricular ejection fraction (≤45%) undergoing median sternotomy for coronary artery bypass grafting. Patients were mostly male (76%) with mild-to-moderate HF and a mean age of 68±10 years. Bone marrow ID was found in 17 (40%) of the HF patients. The most commonly used definition of ID had a sensitivity of 82% and a specificity of 72%. A definition solely based on TSAT ≤19.8% or serum iron ≤13 µmol/L had a sensitivity of 94% and specificity of 84% and 88%, respectively ( P the former definition). Subsequently, we assessed the incidence of all-cause mortality in 387 consecutive outpatient HF patients (left ventricular ejection fraction ≤45%). In these patients, TSAT ≤19.8% and serum iron ≤13 µmol/L, and not ferritin, were independently associated with mortality. A TSAT ≤19.8% or a serum iron ≤13 µmol/L shows the best performance in selecting patients with ID and identifies HF patients at the highest risk of death. Our findings validate the currently used TSAT cutoff of the identification of ID in HF patients, but question the diagnostic value of ferritin. © 2018 American Heart Association, Inc.

  10. Fine-Tuned Intrinsically Ultramicroporous Polymers Redefine the Permeability/Selectivity Upper Bounds of Membrane-Based Air and Hydrogen Separations

    KAUST Repository

    Swaidan, Raja; Ghanem, Bader; Pinnau, Ingo

    2015-01-01

    Intrinsically ultramicroporous (<7 Å) polymers represent a new paradigm in materials development for membrane-based gas separation. In particular, they demonstrate that uniting intrachain “rigidity”, the traditional design metric of highly permeable

  11. Fiber laser cladding of nickel-based alloy on cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Arias-González, F., E-mail: felipeag@uvigo.es [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Val, J. del [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Comesaña, R. [Materials Engineering, Applied Mechanics and Construction Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain); Penide, J.; Lusquiños, F.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pou, J. [Applied Physics Dpt., University of Vigo, EEI, Lagoas-Marcosende, Vigo E-36310 (Spain)

    2016-06-30

    Highlights: • Fiber laser cladding of Ni-based alloy on cast iron was experimentally studied. • Two different types of cast iron have been analyzed: gray and ductile cast iron. • Suitable processing parameters to generate a Ni-based coating were determined. • Dilution is higher in gray cast iron samples than in ductile cast iron. • Ni-based coating presents higher hardness than cast iron but similar Young's modulus. - Abstract: Gray cast iron is a ferrous alloy characterized by a carbon-rich phase in form of lamellar graphite in an iron matrix while ductile cast iron presents a carbon-rich phase in form of spheroidal graphite. Graphite presents a higher laser beam absorption than iron matrix and its morphology has also a strong influence on thermal conductivity of the material. The laser cladding process of cast iron is complicated by its heterogeneous microstructure which generates non-homogeneous thermal fields. In this research work, a comparison between different types of cast iron substrates (with different graphite morphology) has been carried out to analyze its impact on the process results. A fiber laser was used to generate a NiCrBSi coating over flat substrates of gray cast iron (EN-GJL-250) and nodular cast iron (EN-GJS-400-15). The relationship between processing parameters (laser irradiance and scanning speed) and geometry of a single laser track was examined. Moreover, microstructure and composition were studied by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray Diffraction (XRD). The hardness and elastic modulus were analyzed by means of micro- and nanoindentation. A hardfacing coating was generated by fiber laser cladding. Suitable processing parameters to generate the Ni-based alloy coating were determined. For the same processing parameters, gray cast iron samples present higher dilution than cast iron samples. The elastic modulus is similar for the coating and the substrate, while the Ni-based

  12. A plate reader-based method for cell water permeability measurement

    DEFF Research Database (Denmark)

    Fenton, Robert A.; Moeller, H B; Nielsen, S

    2010-01-01

    Cell volume and water permeability measurements in cultured mammalian cells are typically conducted under a light microscope. Many of the employed approaches are time consuming and not applicable to a study of confluent epithelial cell monolayers. We present here an adaptation of a calcein......: AQP2-S256D > AQP2 wild-type > AQP2-S256A. We propose that the method can be applied to study AQP function and more generally to study cell volume changes in adherent cell lines. Furthermore, it should be adaptable for AQP inhibitor screening in chemical compound libraries....

  13. Cut-off frequency of magnetostrictive materials based on permeability spectra

    International Nuclear Information System (INIS)

    Meng Hao; Zhang Tianli; Jiang Chengbao

    2012-01-01

    The loss behavior and cut-off frequency of TbDyFe alloy and TbDyFe/epoxy composite have been investigated by measuring their permeability spectra. The loss factor of TbDyFe alloy increases exponentially as the frequency goes up, while it is almost unchanged for the TbDyFe/epoxy composite. The loss factor value for the TbDyFe composite is only 4.3% of that for the monolithic TbDyFe alloy at high frequency of 10 kHz under the peak magnetic induction of 10 mT. The cut-off frequency of TbDyFe/epoxy composite is 6800 kHz, 3 orders of magnitude larger than that of TbDyFe alloy. The cut-off frequency is found to be the ferromagnetic resonance frequency and can be calculated from Snoek's law. - Highlights: ► The cut-off frequency of TbDyFe alloy and TbDyFe/epoxy composite has been investigated. ► Permeability spectra are used to study loss behavior and cut-off frequency. ► A mathematic formula is deduced to predict the cut-off frequency. ► TbDyFe/epoxy composite presents high cut-off frequency of 6800 kHz.

  14. Versatile and biomass synthesis of iron-based nanoparticles supported on carbon matrix with high iron content and tunable reactivity

    International Nuclear Information System (INIS)

    Zhang Dongmao; Shi, Sheldon Q.; Pittman, Charles U.; Jiang Dongping; Che Wen; Gai Zheng; Howe, Jane Y.; More, Karren L.; Antonyraj, Arockiasamy

    2012-01-01

    Iron-based nanoparticles supported on carbon (FeNPs-C) have enormous potential for environmental applications. Reported is a biomass-based method for FeNP-C synthesis that involves pyrolysis of bleached wood fiber pre-mixed with Fe 3 O 4 nanoparticles. This method allows synthesis of iron-based nanoparticles with tunable chemical reactivity by changing the pyrolysis temperature. The FeNP-C synthesized at a pyrolysis temperature of 500 °C (FeNP-C-500) reacts violently (pyrophoric) when exposed to air, while FeNP-C prepared at 800 °C (FeNP-C-800) remains stable in ambient condition for at least 3 months. The FeNPs in FeNP-C-800 are mostly below 50 nm in diameter and are surrounded by carbon. The immediate carbon layer (within 5–15 nm radius) on the FeNPs is graphitized. Proof-of-concept environmental applications of FeNPs-C-800 were demonstrated by Rhodamine 6G and arsenate (V) removal from water. This biomass-based method provides an effective way for iron-based nanoparticle fabrication and biomass utilization.

  15. Microstructure and structural phase transitions in iron-based superconductors

    International Nuclear Information System (INIS)

    Wang Zhen; Cai Yao; Yang Huai-Xin; Tian Huan-Fang; Wang Zhi-Wei; Ma Chao; Chen Zhen; Li Jian-Qi

    2013-01-01

    Crystal structures and microstructural features, such as structural phase transitions, defect structures, and chemical and structural inhomogeneities, are known to have profound effects on the physical properties of superconducting materials. Recently, many studies on the structural properties of Fe-based high-T c superconductors have been published. This review article will mainly focus on the typical microstructural features in samples that have been well characterized by physical measurements. (i) Certain common structural features are discussed, in particular, the crystal structural features for different superconducting families, the local structural distortions in the Fe 2 Pn 2 (Pn = P As, Sb) or Fe 2 Ch 2 (Ch = S, Se, Te) blocks, and the structural transformations in the 122 system. (ii) In FeTe(Se) (11 family), the superconductivity, chemical and structural inhomogeneities are investigated and discussed in correlation with superconductivity. (iii) In the K 0.8 Fe 1.6+x Se 2 system, we focus on the typical compounds with emphasis on the Fe-vacancy order and phase separations. The microstructural features in other superconducting materials are also briefly discussed. (topical review - iron-based high temperature superconductors)

  16. Degradation of polychlorinated biphenyls using mesoporous iron-based spinels

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Linyan; Su, Guijin, E-mail: gjsu@rcees.ac.cn; Zhang, Aiqian; Shi, Yali; Xia, Chaobo; Lu, Huijie; Li, Liewu; Liu, Sha; Zheng, Minghui

    2013-10-15

    Highlights: • The NiFe{sub 2}O{sub 4} had the highest activity in degradation of CB-209, followed by Fe{sub 3}O{sub 4}. • Hydroxyl species, organic acids, PCBs and chlorobenzenes were identified as products. • Three degradation reactions and one combination reaction competitively occurred. • Hydrodechlorination of CB-209 was more favored over Fe{sub 3}O{sub 4} than NiFe{sub 2}O{sub 4}. • Oxidation reaction of CB-209 was more favored over NiFe{sub 2}O{sub 4} than Fe{sub 3}O{sub 4}. -- Abstract: A series of mesoporous iron-based spinel materials were synthesized to degrade polychlorinated biphenyls (PCBs), with CB-209 being used as a model compound. The materials were characterized by X-ray powder diffraction (XRD), pore structure analysis, and X-ray photoelectron spectroscopy (XPS). A comparison of the dechlorination efficiencies (DEs) of the materials revealed that NiFe{sub 2}O{sub 4} had the highest DE, followed by Fe{sub 3}O{sub 4}. Newly produced polychlorinated biphenyls, chlorinated benzenes, hydroxyl species and organic acids were detected by gas chromatography–mass spectrometry, high performance liquid chromatography–mass spectrometry and ion chromatograph. Identification of the intermediate products indicates that three degradation pathways, hydrodechlorination, the breakage of C-C bridge bond and oxidative reaction, accompanied by one combination reaction, are competitively occurring over the iron-based spinels. The relative amounts of produced three NoCB isomers were illustrated by the C-Cl BDEs of CB-209 at meta-, para- and ortho-positions, and their energy gap between HOMO and LUMO. The consumption of the reactive oxygen species caused by the transformation of Fe{sub 3}O{sub 4} into Fe{sub 2}O{sub 3} in the Fe{sub 3}O{sub 4} reaction system, and the existence of the highly reactive O{sub 2}{sup −}· species in the NiFe{sub 2}O{sub 4} reaction system, could provide a reason why the oxidation reaction was more favored over NiFe{sub 2}O

  17. MATHEMATICAL MODELING AND NUMERICAL SOLUTION OF IRON CORROSION PROBLEM BASED ON CONDENSATION CHEMICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    Basuki Widodo

    2012-02-01

    Full Text Available Corrosion process is a natural case that happened at the various metals, where the corrosion process in electrochemical can be explained by using galvanic cell. The iron corrosion process is based on the acidity degree (pH of a condensation, iron concentration and condensation temperature of electrolyte. Those are applied at electrochemistry cell. The iron corrosion process at this electrochemical cell also able to generate electrical potential and electric current during the process takes place. This paper considers how to build a mathematical model of iron corrosion, electrical potential and electric current. The mathematical model further is solved using the finite element method. This iron corrosion model is built based on the iron concentration, condensation temperature, and iteration time applied. In the electric current density model, the current based on electric current that is happened at cathode and anode pole and the iteration time applied. Whereas on the potential  electric model, it is based on the beginning of electric potential and the iteration time applied. The numerical results show that the part of iron metal, that is gristle caused by corrosion, is the part of metal that has function as anode and it has some influences, such as time depth difference, iron concentration and condensation temperature on the iron corrosion process and the sum of reduced mass during corrosion process. Moreover, difference influence of time and beginning electric potential has an effect on the electric potential, which emerges during corrosion process at the electrochemical cell. Whereas, at the electrical current is also influenced by difference of depth time and condensation temperature applied.Keywords: Iron Corrosion, Concentration of iron, Electrochemical Cell and Finite Element Method

  18. Rapid decision support tool based on novel ecosystem service variables for retrofitting of permeable pavement systems in the presence of trees.

    Science.gov (United States)

    Scholz, Miklas; Uzomah, Vincent C

    2013-08-01

    The retrofitting of sustainable drainage systems (SuDS) such as permeable pavements is currently undertaken ad hoc using expert experience supported by minimal guidance based predominantly on hard engineering variables. There is a lack of practical decision support tools useful for a rapid assessment of the potential of ecosystem services when retrofitting permeable pavements in urban areas that either feature existing trees or should be planted with trees in the near future. Thus the aim of this paper is to develop an innovative rapid decision support tool based on novel ecosystem service variables for retrofitting of permeable pavement systems close to trees. This unique tool proposes the retrofitting of permeable pavements that obtained the highest ecosystem service score for a specific urban site enhanced by the presence of trees. This approach is based on a novel ecosystem service philosophy adapted to permeable pavements rather than on traditional engineering judgement associated with variables based on quick community and environment assessments. For an example case study area such as Greater Manchester, which was dominated by Sycamore and Common Lime, a comparison with the traditional approach of determining community and environment variables indicates that permeable pavements are generally a preferred SuDS option. Permeable pavements combined with urban trees received relatively high scores, because of their great potential impact in terms of water and air quality improvement, and flood control, respectively. The outcomes of this paper are likely to lead to more combined permeable pavement and tree systems in the urban landscape, which are beneficial for humans and the environment. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Oxygen permeability of nanocomposite-based polyolefin films; Permeabilidade do oxigenio em filmes nanocompositos poliolefinicos

    Energy Technology Data Exchange (ETDEWEB)

    Fujiyama-Novak, Jane H.; Amaral, Rafael A.; Ruffino, Vivianne; Habert, A. Claudio; Borges, Cristiano P., E-mail: jane@peq.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEQ/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Mano, Barbara [BRASKEM S.A., Duque de Caxias, RJ (Brazil)

    2015-07-01

    Polyethylene and polypropylene are vastly employed for packaging due to their high versatility and low cost. However, their films are permeable at different degree to small molecules like gases and the use of additives improves the barrier properties. Therefore, the aim of this work is to investigate the effect of organically modified montmorillonite on oxygen transport properties of PE and PP films. Nanocomposites were prepared by means of polymer dissolution in organic solvent and subsequent nanoparticle addition at 3, 5 and 10% (w/w). Scanning electron microscopy images of the films indicate the presence of microcavities and some agglomerated nanoclay. On the other hand, X-rays diffraction analysis shows clay in well-dispersed state independent of polyolefin type. Enhancement of oxygen barrier is achieved, but this property is dependent on the nanoclay content, polyolefin type and film morphology. (author)

  20. Optimum Mix for Pervious Geopolymer Concrete (GEOCRETE Based on Water Permeability and Compressive Strength

    Directory of Open Access Journals (Sweden)

    Abdulsalam Arafa Salaheddin

    2017-01-01

    Full Text Available The production of ordinary Portland cement (OPC consumes considerable natural resources and energy, and it also affects the emission of a significant quantity of CO2 in the atmosphere. This pervious geopolymer concrete study aims to explore an alternative binder without OPC. Pervious geopolymer concretes were prepared from fly ash (FA, sodium silicate (NaSiO3, sodium hydroxide (NaOH solution, and coarse aggregate (CA. The effects of pervious geopolymer concrete parameters that affect water permeability and compressive strength are evaluated. The FA to CA ratios of 1:6, 1:7,1:8, and 1:9 by weight, CA sizes of 5–10, 10–14, and 14–20 mm, constant NaSiO3/NaOH ratio of 2.5, alkaline liquid to fly ash (AL/FA ratios of 0.4, 0.5, and 0.6, and NaOH concentrations of 8, 10, and 12 M were the pervious geopolymer concrete mix proportions. The curing temperature of 80 °C for 24 h was used. The results showed that a pervious geopolymer concrete with CA of 10 mm achieved water permeability of 2.3 cm/s and compressive strength of 20 MPa with AL/FA ratio of 0.5, NaOH concentration of 10 M, and FA:CA of 1:7. GEOCRETE is indicated to have better engineering properties than does pervious concrete that is made of ordinary Portland cement.

  1. A comparison of etched-geometry and overgrown silicon permeable base transistors by two-dimensional numerical simulations

    Science.gov (United States)

    Vojak, B. A.; Alley, G. D.

    1983-08-01

    Two-dimensional numerical simulations are used to compare etched geometry and overgrown Si permeable base transistors (PTBs), considering both the etched collector and etched emitter biasing conditions made possible by the asymmetry of the etched structure. In PTB devices, the two-dimensional nature of the depletion region near the Schottky contact base grating results in a smaller electron barrier and, therefore, a larger collector current in the etched than in the overgrown structure. The parasitic feedback effects which result at high base-to-emitter bias levels lead to a deviation from the square-law behavior found in the collector characteristics of the overgrown PBT. These structures also have lower device capacitances and smaller transconductances at high base-to-emitter voltages. As a result, overgrown and etched structures have comparable predicted maximum values of the small signal unity short-circuit current gain frequency and maximum oscillation frequency.

  2. Plasticized Starch Based Bionanocomposites Containing Cellulose Nanowhiskers and Titanium Dioxide Nanoparticles: Study of Structure and Water Vapor Permeability

    Directory of Open Access Journals (Sweden)

    Nasrin Jamshidi Kaljahi

    2014-08-01

    Full Text Available The starch-based films have some disadvantages such as weak mechanical and poor water barrier properties that restrict their applications in food packaging. In the present research, to improve the properties of the starch films, a constant level of citric acid and polyvinyl alcohol (PVA (10% with different amounts of glycerol (GLY as a lubricating agent, crystal nanowhiskers (CNW and titanium dioxide (TiO2 nanoparticles were used together. Finally, the effects of these compounds on permeability properties of the obtained starch-based bionanocomposites were studied and their optimum values were determined by central composite design of response surface methodology (RSM. The results of X-Ray diffraction (XRD test showed that at low levels of TiO2 and CNW there was no diffractogram peak obtained. However, at high levels of TiO2 and CNW there emerged distinct and sharp peak which was attributed to greater crystalline region and probably non-homogeneity in particle distribution. The Fourier transmission infrared (FTIR data showed that addition of CNW and TiO2 increased hydrogen binding between the nanofillers and biopolymer matrix. The effects of TiO2 and CNW concentrations as quadratic and glycerol concentration as linear and quadratic were significant on water vapor permeability (WVP. The optimum levels of TiO2, CNW and GLY for obtaining minimum WVP corresponded to 0.118, 0.3 g and 1.06 mL, respectively.

  3. Association of dietary and supplemental iron and colorectal cancer in a population-based study.

    Science.gov (United States)

    Ashmore, Joseph H; Lesko, Samuel M; Miller, Paige E; Cross, Amanda J; Muscat, Joshua E; Zhu, Junjia; Liao, Jason; Harper, Gregory; Lazarus, Philip; Hartman, Terryl J

    2013-11-01

    We evaluated the role of dietary iron, heme iron, and supplemental iron on colorectal cancer (CRC) risk in a population-based case-control study in Pennsylvania, including 1005 incident cases and 1062 controls. Diet was assessed through a modified food frequency questionnaire that included supplement use and a meat-specific module. Cases reported intakes for the year before diagnosis, whereas controls reported intakes for the year before interview. Heme iron intake was calculated using a new heme database developed by the US National Cancer Institute. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression. After multivariate adjustment, there were no significant associations between heme iron or total iron intake and CRC incidence. Dietary iron intake was inversely associated with CRC among women (OR Q5 vs. Q1=0.45; 95% CI=0.22-0.92), but not among men. Supplemental iron intake of more than 18 mg/day versus none was positively associated with CRC incidence (OR=2.31; 95% CI=1.48-3.59; P-trendconsumption of more than 18 mg/day of supplemental iron may increase risk for CRC.

  4. Comparative Review on Thin Film Growth of Iron-Based Superconductors

    Directory of Open Access Journals (Sweden)

    Yoshinori Imai

    2017-07-01

    Full Text Available Since the discovery of the novel iron-based superconductors, both theoretical and experimental studies have been performed intensively. Because iron-based superconductors have a smaller anisotropy than high-Tc cuprates and a high superconducting transition temperature, there have been a lot of researchers working on the film fabrication of iron-based superconductors and their application. Accordingly, many novel features have been reported in the films of iron-based superconductors, for example, the fabrication of the epitaxial film with a higher Tc than bulk samples, the extraction of the metastable phase which cannot be obtained by the conventional solid state reaction, and so on. In this paper, we review the progress of research on thin film fabrications of iron-based superconductors, especially the four categories: LnFeAs(O,F (Ln = Lanthanide, AEFe2As2 (AE = Alkaline-earth metal, FeCh (Ch = Chalcogen, and FeSe monolayer. Furthermore, we focus on two important topics in thin films of iron-based superconductors; one is the substrate material for thin film growth on the iron-based superconductors, and the other is the whole phase diagram in FeSe1-xTex which can be obtained only by using film-fabrication technique.

  5. Nematic fluctuations and resonance in iron-based superconductors

    Science.gov (United States)

    Gallais, Yann

    The spontaneous appearance of nematicity, a state of matter that breaks rotation but not translation symmetry, is ubiquitous in many iron based superconductors (Fe SC), and has relevance for the cuprates as well. Here I will review recent electronic Raman scattering experiments which report the presence of critical nematic fluctuations in the charge channel in the tetragonal phase of several Fe SC systems. In electron doped Co-BaFe2As2 (Co-Ba122), these fluctuations extend over most of the superconducting dome. Their associated nematic susceptibility shows Curie-Weiss behavior, and its doping dependence suggests the presence of a nematic quantum critical point near optimal TC Similar nematic fluctuations are also observed in FeSe despite the absence of magnetic order, raising the question of the link between nematicity and magnetism in Fe SC. In FeSe I will further contrast the evolution of nematic fluctuations under isoelectronic S substitution and hydrostatic pressures up to 8 GPa, with only the former showing evidence for a nematic quantum critical point. In the superconducting state of Co-Ba122, I will show that a resonance emerges in the Raman spectra near the nematic quantum critical point. This nematic resonance is a clear fingerprint of the coupling between nematic fluctuations and Bogoliubov quasiparticles, and can be thought as the nematic counterpart of the spin resonance observed in neutron scattering experiments. Support from Agence Nationale de la Recherche via ANR Grant ''Pnictides'' is acknowledged.

  6. Oxidation influence on crystallisation in iron-based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gloriant, T.; Surinach, S.; Munoz, J.S.; Baro, M.D. [Universitat Autonoma de Barcelona (Spain). Dept. de Fisica; Inoue, A. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    2001-07-01

    The partially crystalline iron-based nanophase composites elaborated by rapid solidification techniques are very attractive for their excellent soft magnetic properties and their potential for industrial applications. In these nanocomposite materials a control of both the structure (size, shape and distribution of the nanoparticles in the amorphous matrix) and the kinetic behaviour (nucleation and growth mechanism) is essential in order to obtain the best properties and to be able to produce them at the industrial scale. Our group has been working in this research area for a long time and the investigation presented here is the result of an international collaboration. This study deals with the effect of cobalt addition in Fe-Nb-B melt-spun amorphous alloys on the devitrification/crystallisation processes induced by thermal treatments and characterised by X-ray diffraction analysis (XRD), thermomagnetic analysis (TMG) and transmission electron microscopy observations (TEM). The transformation sequences, from the initial amorphous phase to the fully crystallised final state, were carried out using different annealing experiments (under vacuum and in air) and have revealed a strong influence of the environmental atmosphere during devitrification. It is shown that oxidation can greatly affect the crystallisation behaviour as a result of the high metastable state of the initial amorphous phase. The results and observations of this phenomenon will be presented. (orig.)

  7. Theoretical study of impurity effects in iron-based superconductors

    Science.gov (United States)

    Navarro Gastiasoro, Maria; Hirschfeld, Peter; Andersen, Brian

    2013-03-01

    Several open questions remain unanswered for the iron-based superconductors (FeSC), including the importance of electronic correlations and the symmetry of the superconducting order parameter. Motivated by recent STM experiments which show a fascinating variety of resonant defect states in FeSC, we adopt a realistic five-band model including electronic Coulomb correlations to study local effects of disorder in the FeSC. In order to minimize the number of free parameters, we use the pairing interactions obtained from spin-fluctuation exchange to determine the homogeneous superconducting state. The ability of local impurity potentials to induce resonant states depends on their scattering strength Vimp; in addition, for appropriate Vimp, such states are associated with local orbital- and magnetic order. We investigate the density of states near such impurities and show how tunneling experiments may be used to probe local induced order. In the SDW phase, we show how C2 symmetry-breaking dimers are naturally formed around impurities which also form cigar-like (pi,pi) structures embedded in the (pi,0) magnetic bulk phase. Such electronic dimers have been shown to be candidates for explaining the so-called nematogens observed previously by QPI in Co-doped CaFe2As2.

  8. Influence of diurnal variation and fasting on serum iron concentrations in a community-based population.

    Science.gov (United States)

    Nguyen, Leonard T; Buse, Joshua D; Baskin, Leland; Sadrzadeh, S M Hossein; Naugler, Christopher

    2017-12-01

    Serum iron is an important clinical test to help identify cases of iron deficiency or overload. Fluctuations caused by diurnal variation and diet are thought to influence test results, which may affect clinical patient management. We examined the impact of these preanalytical factors on iron concentrations in a large community-based cohort. Serum iron concentration, blood collection time, fasting duration, patient age and sex were obtained for community-based clinical testing from the Laboratory Information Service at Calgary Laboratory Services for the period of January 2011 to December 2015. A total of 276,307 individual test results were obtained. Iron levels were relatively high over a long period from 8:00 to 15:00. Mean concentrations were highest at blood collection times of 11:00 for adult men and 12:00 for adult women and children, however iron levels peaked as late as 15:00 in teenagers. With regard to fasting, iron levels required approximately 5h post-prandial time to return to a baseline, except for children and teenage females where no significant variation was seen until after 11h fasting. After 10h fasting, iron concentrations in all patient groups gradually increased to higher levels compared to earlier fasting times. Serum iron concentrations remain reasonably stable during most daytime hours for testing purposes. In adults, blood collection after 5 to 9h fasting provides a representative estimate of a patient's iron levels. For patients who have fasted overnight, i.e. ≥12h fasting, clinicians should be aware that iron concentrations may be elevated beyond otherwise usual levels. Copyright © 2017. Published by Elsevier Inc.

  9. Simple algorithm to estimate mean-field effects from minor differential permeability curves based on the Preisach model

    International Nuclear Information System (INIS)

    Perevertov, Oleksiy

    2003-01-01

    The classical Preisach model (PM) of magnetic hysteresis requires that any minor differential permeability curve lies under minor curves with larger field amplitude. Measurements of ferromagnetic materials show that very often this is not true. By applying the classical PM formalism to measured minor curves one can discover that it leads to an oval-shaped region on each half of the Preisach plane where the calculations produce negative values in the Preisach function. Introducing an effective field, which differs from the applied one by a mean-field term proportional to the magnetization, usually solves this problem. Complex techniques exist to estimate the minimum necessary proportionality constant (the moving parameter). In this paper we propose a simpler way to estimate the mean-field effects for use in nondestructive testing, which is based on experience from the measurements of industrial steels. A new parameter (parameter of shift) is introduced, which monitors the mean-field effects. The relation between the shift parameter and the moving one was studied for a number of steels. From preliminary experiments no correlation was found between the shift parameter and the classical magnetic ones such as the coercive field, maximum differential permeability and remanent magnetization

  10. Determination of hydrogen permeability in commercial and modified superalloys

    Science.gov (United States)

    Bhattacharyya, S.; Peterman, W.

    1983-01-01

    The results of hydrogen permeability measurements on several iron- and cobalt-base alloys as well as on two long-ranged ordered alloys over the range of 705 to 870 C (1300 to 1600 F) are summarized. The test alloys included wrought alloys N-155, IN 800, A-286, 19-9DL, and 19-9DL modifications with aluminum, niobium, and misch metal. In addition, XF-818, CRM-6D, SA-F11, and HS-31 were evaluated. Two wrought long-range ordered alloys, Ni3Al and (Fe,Ni)3(V,Al) were also evaluated. All tests were conducted at 20.7 MPa pressure in either pure and/or 1% CO2-doped H2 for test periods as long as 133 h. Detailed analyses were conducted to determine the relative permeability rankings of these alloys and the effect of doping, exit surface oxidation, specimen design variations, and test duration on permeability coefficient, and permeation activation energies were determined. The two long-range ordered alloys had the lowest permeability coefficients in pure H2 when compared with the eight commercial alloys and their modifications. With CO2 doping, significant decrease in permeability was observed in commercial alloys--no doped tests were conducted with the long-range ordered alloys.

  11. Positron Emission Tomography Based Elucidation of the Enhanced Permeability and Retention Effect in Dogs with Cancer Using Copper-64 Liposomes

    DEFF Research Database (Denmark)

    Hansen, Anders Elias; Petersen, Anncatrine Luisa; Henriksen, Jonas Rosager

    2015-01-01

    Since the first report of the enhanced permeability and retention (EPR) effect, the research in nanocarrier based antitumor drugs has been intense. The field has been devoted to treatment of cancer by exploiting EPR-based accumulation of nanocarriers in solid tumors, which for many years...... was considered to be a ubiquitous phenomenon. However, the understanding of differences in the EPR-effect between tumor types, heterogeneities within each patient group, and dependency on tumor development stage in humans is sparse. It is therefore important to enhance our understanding of the EPR......-effect in large animals and humans with spontaneously developed cancer. In the present paper, we describe a novel loading method of copper-64 into PEGylated liposomes and use these liposomes to evaluate the EPR-effect in 11 canine cancer patients with spontaneous solid tumors by PET/CT imaging. We thereby provide...

  12. Arsenate and Arsenite Sorption on Magnetite: Relations to Groundwater Arsenic Treatment Using Zerovalent Iron and Natural Attenuation

    Science.gov (United States)

    Magnetite (Fe3O4) is a zerovalent iron corrosion product; it is also formed in natural soil and sediment. Sorption of arsenate (As(V)) and arsenite (As(III)) on magnetite is an important process of arsenic removal from groundwater using zerovalent iron-based permeable reactive ba...

  13. Studies on the optimum conditions using acid-washed zero-valent iron/aluminum mixtures in permeable reactive barriers for the removal of different heavy metal ions from wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Han, Weijiang [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); South China Institute of Environmental Science, MEP, Guangzhou 510655 (China); Fu, Fenglian, E-mail: fufenglian2006@163.com [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Cheng, Zihang; Tang, Bing; Wu, Shijiao [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2016-01-25

    Highlights: • Acid-washed zero-valent iron and zero-valent aluminum were used in PRBs. • The time that removal efficiencies of heavy metal were above 99.5% can keep 300 h. • Removal mechanism of Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} was discussed. • Heavy metal ions were removed by reduction, adsorption, and co-precipitation. - Abstract: The method of permeable reactive barriers (PRBs) is considered as one of the most practicable approaches in treating heavy metals contaminated surface and groundwater. The mixture of acid-washed zero-valent iron (ZVI) and zero-valent aluminum (ZVAl) as reactive medium in PRBs to treat heavy metal wastewater containing Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} was investigated. The performance of column filled with the mixture of acid-washed ZVI and ZVAl was much better than the column filled with ZVI or ZVAl alone. At initial pH 5.4 and flow rates of 1.0 mL/min, the time that the removal efficiencies of Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} were all above 99.5% can keep about 300 h using 80 g/40 g acid-washed ZVI/ZVAl when treating wastewater containing each heavy metal ions (Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+}) concentration of 20.0 mg/L. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize ZVI/ZVAl before and after reaction and the reaction mechanism of the heavy metal ions with ZVI/ZVAl was discussed.

  14. Studies on the optimum conditions using acid-washed zero-valent iron/aluminum mixtures in permeable reactive barriers for the removal of different heavy metal ions from wastewater

    International Nuclear Information System (INIS)

    Han, Weijiang; Fu, Fenglian; Cheng, Zihang; Tang, Bing; Wu, Shijiao

    2016-01-01

    Highlights: • Acid-washed zero-valent iron and zero-valent aluminum were used in PRBs. • The time that removal efficiencies of heavy metal were above 99.5% can keep 300 h. • Removal mechanism of Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ was discussed. • Heavy metal ions were removed by reduction, adsorption, and co-precipitation. - Abstract: The method of permeable reactive barriers (PRBs) is considered as one of the most practicable approaches in treating heavy metals contaminated surface and groundwater. The mixture of acid-washed zero-valent iron (ZVI) and zero-valent aluminum (ZVAl) as reactive medium in PRBs to treat heavy metal wastewater containing Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ was investigated. The performance of column filled with the mixture of acid-washed ZVI and ZVAl was much better than the column filled with ZVI or ZVAl alone. At initial pH 5.4 and flow rates of 1.0 mL/min, the time that the removal efficiencies of Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ were all above 99.5% can keep about 300 h using 80 g/40 g acid-washed ZVI/ZVAl when treating wastewater containing each heavy metal ions (Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ) concentration of 20.0 mg/L. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize ZVI/ZVAl before and after reaction and the reaction mechanism of the heavy metal ions with ZVI/ZVAl was discussed.

  15. X-ray CT analysis on archaeological iron based artifacts

    International Nuclear Information System (INIS)

    Honda, Takashi; Gunji, Eiichi

    2005-01-01

    Corrosion analysis was carried out on twenty iron-plates, which had been dug out at the 6th Yamato ancient tomb (Nara-shi). It was evaluated through the inner-structural analysis by X-ray CT and the XRD and chemical analysis of the rusts that the most iron-plates had been buried in a slightly oxidizing environment and the maximum corrosion depth was 1.6 mm for about 1500 years. The analysis result of the extreme-value data indicates that the maximum depth of an overpack is estimated to be 2.5-2.7 mm. A part of small iron-plates were supposed to have been buried in an oxidizing environment, and about 1 mm-thick rust layers with cavities existed and the corrosion amount was figured out to be about 0.3 mm. (author)

  16. Microbial siderophore-based iron assimilation and therapeutic applications.

    Science.gov (United States)

    Li, Kunhua; Chen, Wei-Hung; Bruner, Steven D

    2016-06-01

    Siderophores are structurally diverse, complex natural products that bind metals with extraordinary specificity and affinity. The acquisition of iron is critical for the survival and virulence of many pathogenic microbes and diverse strategies have evolved to synthesize, import and utilize iron. There has been a substantial increase of known siderophore scaffolds isolated and characterized in the past decade and the corresponding biosynthetic gene clusters have provided insight into the varied pathways involved in siderophore biosynthesis, delivery and utilization. Additionally, therapeutic applications of siderophores and related compounds are actively being developed. The study of biosynthetic pathways to natural siderophores augments the understanding of the complex mechanisms of bacterial iron acquisition, and enables a complimentary approach to address virulence through the interruption of siderophore biosynthesis or utilization by targeting the key enzymes to the siderophore pathways.

  17. FIR spectroscopy of iron-based semimagnetic semiconductors

    NARCIS (Netherlands)

    Hausenblas, M.; Claessen, L.M.; Wittlin, A.; Twardowski, A.; Ortenberg, von M.; Jonge, de W.J.M.; Wyder, P.

    1989-01-01

    We report far-infrared studies of low energy levels of Fe2+ ions in ZnSe and related wide-gap semimagnetic semiconductors in magnetic fields up to 20 T. Transitions between 5E levels are observed and the experimental results are in good agreement with the standard model of single iron impurities in

  18. Microbial synthesis of iron-based nanomaterials—A review

    Indian Academy of Sciences (India)

    Nanoparticles; biosynthesis; microbes; iron reducing bacteria; sulphate reducing bacteria; magnetotactic bacteria. 1. Introduction. Nanoparticles are considered to be the building blocks for nanotechnology and are referred to as the particles having one or more dimensions of the order of 100 nm or less. (Huber 2005).

  19. Iron-based granules in body of bumblebees

    Czech Academy of Sciences Publication Activity Database

    Jandacka, P.; Kasparova, B.; Jirásková, Yvonna; Dedkova, K.; Mamulová-Kutláková, K.; Kukutschová, J.

    2015-01-01

    Roč. 28, č. 1 (2015), s. 89-99 ISSN 0966-0844 R&D Projects: GA ČR(CZ) GAP108/11/1350 Institutional support: RVO:68081723 Keywords : Magnetoreception * Bumblebee * Biomineralisation * Iron granules Subject RIV: BO - Biophysics Impact factor: 2.134, year: 2015

  20. Soft material-based microculture system having air permeable cover sheet for the protoplast culture of Nicotiana tabacum.

    Science.gov (United States)

    Ju, Jong Il; Ko, Jung-Moon; Kim, So Hyeon; Baek, Ju Yeoul; Cha, Hyeon-Cheol; Lee, Sang Hoon

    2006-08-01

    In plant cell culture, the delivery of nutrition and gas (mainly oxygen) to the cells is the most important factor for viability. In this paper, we propose a polydimethylsiloxane (PDMS)-based microculture system that is designed to have good aeration. PDMS is known to have excellent air permeability, and through the experimental method, we investigated the relation between the degree of air delivery and the thickness of the PDMS sheet covering the culture chamber. We determined the proper thickness of the cover sheet, and cultured protoplasts of Nicotiana tabacum in a culture chamber covered with a PDMS sheet having thickness of 400 microm. The cells were successfully divided, and lived well inside the culture chamber for 10 days. In addition, protoplasts were cultured inside the culture chambers covered with the cover glass and the PDMS sheet, respectively, and the microcolonies were formed well inside the PDMS covered chamber after 10 days.

  1. AN ALTERNATIVE HOST MATRIX BASED ON IRON PHOSPHATE GLASSES FOR THE VITRIFICATION OF SPECIALIZED WASTE FORMS

    International Nuclear Information System (INIS)

    Day, Delbert D.

    2000-01-01

    As mentioned above, the overall goal of this research project was to collect the scientific information essential to develop iron phosphate glass based nuclear wasteforms. The specific objectives of the project were: (1) Investigate the structure of binary iron phosphate glasses and it's dependence on the composition and melting atmosphere: Understand atomic arrangements and nature of the bonding. Establish structure-property relationships. Determine the compositions and melting conditions which optimize the critical properties of the base glass. (2) Understand the structure of iron phosphate wasteforms and it's dependence on the composition and melting atmosphere: Investigate how the waste elements are bonded and coordinated within the glass structure. Establish structure-property relationships for the waste glasses. Determine the compositions and melting atmosphere for which the critical properties of the waste forms would be optimum. (3) Determine the role(s) played by the valence states of iron ions and it's dependence on the composition and melting atmosphere: Understand the different roles of iron(II) and iron(III) ions in determining the critical properties of the base glass and the waste forms. Investigate how the iron valence and its significance depend on the composition and melting atmosphere. (4) Investigate glass forming and crystallization processes of the iron phosphate glasses and their waste forms: Understand the dependence of the glass forming and crystallization characteristics on overall glass composition and valence states of iron ions. Identify the products of devitrification and investigate the critical properties of these crystalline compounds which may adversely affect the chemical and physical properties of the waste forms

  2. Melting of Grey Cast Iron Based on Steel Scrap Using Silicon Carbide

    Directory of Open Access Journals (Sweden)

    Stojczew A.

    2014-08-01

    Full Text Available The paper presents the issue of synthetic cast iron production in the electric induction furnace exclusively on the steel scrap base. Silicon carbide and synthetic graphite were used as carburizers. The carburizers were introduced with solid charge or added on the liquid metal surface. The chemical analysis of the produced cast iron, the carburization efficiency and microstructure features were presented in the paper. It was stated that ferrosilicon can be replaced by silicon carbide during the synthetic cast iron melting process. However, due to its chemical composition (30% C and 70% Si which causes significant silicon content in iron increase, the carbon deficit can be partly compensated by the carburizer introduction. Moreover it was shown that the best carbon and silicon assimilation rate is obtained where the silicon carbide is being introduced together with solid charge. When it is thrown onto liquid alloy surface the efficiency of the process is almost two times less and the melting process lasts dozen minutes long. The microstructure of the cast iron produced with the silicon carbide shows more bulky graphite flakes than inside the microstructure of cast iron produced on the pig iron base.

  3. Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation; Langzeitverhalten von elementarem Eisen und Hydroxylapatit zur Uranrueckhaltung in permeablen reaktiven Waenden bei der Grundwassersanierung

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, V.

    2007-11-21

    Elemental iron (Fe{sup 0}) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using {sup 237}U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca{sub 5}(PO{sub 4}){sub 3}OH, 99 % < 0.42 mm) supplied by Che-mische Fabrik Budenheim CFB, Germany. Both materials exhibited uranium retention of more than 99.9% and sorption capacities of up to 28.3 mg U/g HAP and more than 38.4 mg U/g Fe{sup 0} (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe{sup 0} columns with effluent uranium con-centrations being below the detection limit of 10 {mu}g/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe{sup 0} columns with 200 PV of uranium free AGW. However, columns with high Fe{sup 0} content ({>=} 50%) suffered from severe loss of permeability when AGW with {>=} 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 {mu}g/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing

  4. Studies on neutron irradiation effects of iron alloys and nickel-base heat resistant alloys

    International Nuclear Information System (INIS)

    Watanabe, Katsutoshi

    1987-09-01

    The present paper describes the results of neutron irradiation effects on iron alloys and nickel-base heat resistant alloys. As for the iron alloys, irradiation hardening and embrittlement were investigated using internal friction measurement, electron microscopy and tensile testings. The role of alloying elements was also investigated to understand the irradiation behavior of iron alloys. The essential factors affecting irradiation hardening and embrittlement were thus clarified. On the other hand, postirradiation tensile and creep properties were measured of Hastelloy X alloy. Irradiation behavior at elevated temperatures is discussed. (author)

  5. Structure and properties of composite iron-based coatings obtained by the electromechanical technique

    Science.gov (United States)

    Dubinskii, N. A.

    2007-09-01

    The influence of the electrolyte temperature and current density on the content of inclusions of powder particles in composite coatings obtained by the electrochemical technique has been investigated. It has been found that the wear resistance of iron coatings with inclusions of powder particles of aluminum, kaolin, and calcium silicate increases from 5 to 10 times compared to coating without inclusions of disperse particles, and the friction coefficient therewith decreases from 0.097 to 0.026. It has been shown that the mechanical properties of iron obtained by the method of electrochemical deposition depend on their fine structure. The regimes of deposition of iron-based coatings have been optimized.

  6. Crystal growth iron based pnictide compounds; Kristallzuechtung eisenbasierter Pniktidverbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Nacke, Claudia

    2012-11-15

    The present work is concerned with selected crystal growth method for producing iron-based superconductors. The first part of this work introduces significant results of the crystal growth of BaFe{sub 2}As{sub 2} and the cobalt-substituted compound Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} with x{sub Nom} = 0.025, 0.05, 0.07, 0.10 and 0.20. For this purpose a test procedure for the vertical Bridgman method was developed. The second part of this work contains substantial results for growing a crystal of LiFeAs and the nickel-substituted compound Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As with x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 and 0.10. For this purpose a test procedure for the melt flow process has been developed successfully. [German] Die vorliegende Arbeit befasst sich mit ausgewaehlten Kristallzuechtungsverfahren zur Herstellung eisenbasierter Supraleiter. Der erste Teil dieser Arbeit fuehrt wesentliche Ergebnisse der Kristallzuechtung von BaFe{sub 2}As{sub 2} sowie der Cobalt-substituierten Verbindung Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} mit x{sub Nom} =0.025, 0.05, 0.07, 0.10 und 0.20 auf. Hierzu wurde eine Versuchsdurchfuehrung fuer das vertikale Bridgman-Verfahren konzipiert, mit welcher erfolgreich Kristalle dieser Zusammensetzungen gezuechtet wurden. Der zweite Teil dieser Arbeit enthaelt wesentliche Ergebnisse zur Kristallzuechtung von LiFeAs sowie der Nickel-substituierten Verbindung Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As mit x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 und 0.10. Hierfuer wurde erfolgreich eine Versuchsdurchfuehrung fuer das Schmelzfluss-Verfahren entwickelt.

  7. Interplay between superconductivity and magnetism in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chubukov, Andrey V [University of Wisconsin

    2015-06-10

    This proposal is for theoretical work on strongly correlated electron systems, which are at the center of experimental and theoretical activities in condensed-matter physics. The interest to this field is driven fascinating variety of observed effects, universality of underlying theoretical ideas, and practical applications. I propose to do research on Iron-based superconductors (FeSCs), which currently attract high attention in the physics community. My goal is to understand superconductivity and magnetism in these materials at various dopings, the interplay between the two, and the physics in the phase in which magnetism and superconductivity co-exist. A related goal is to understand the origin of the observed pseudogap-like behavior in the normal state. My research explores the idea that superconductivity is of electronic origin and is caused by the exchange of spin-fluctuations, enhanced due to close proximity to antiferromagnetism. The multi-orbital/multi-band nature of FeSCs opens routes for qualitatively new superconducting states, particularly the ones which break time-reversal symmetry. By all accounts, the coupling in pnictdes is below the threshold for Mott physics and I intend to analyze these systems within the itinerant approach. My plan is to do research in two stages. I first plan to address several problems within weak-coupling approach. Among them: (i) what sets stripe magnetic order at small doping, (ii) is there a preemptive instability into a spin-nematic state, and how stripe order affects fermions; (iii) is there a co-existence between magnetism and superconductivity and what are the system properties in the co-existence state; (iv) how superconductivity emerges despite strong Coulomb repulsion and can the gap be s-wave but with nodes along electron FSs, (v) are there complex superconducting states, like s+id, which break time reversal symmetry. My second goal is to go beyond weak coupling and derive spin-mediated, dynamic interaction between

  8. New Technique for TOC Estimation Based on Thermal Core Logging in Low-Permeable Formations (Bazhen fm.)

    Science.gov (United States)

    Popov, Evgeny; Popov, Yury; Spasennykh, Mikhail; Kozlova, Elena; Chekhonin, Evgeny; Zagranovskaya, Dzhuliya; Belenkaya, Irina; Alekseev, Aleksey

    2016-04-01

    A practical method of organic-rich intervals identifying within the low-permeable dispersive rocks based on thermal conductivity measurements along the core is presented. Non-destructive non-contact thermal core logging was performed with optical scanning technique on 4 685 full size core samples from 7 wells drilled in four low-permeable zones of the Bazhen formation (B.fm.) in the Western Siberia (Russia). The method employs continuous simultaneous measurements of rock anisotropy, volumetric heat capacity, thermal anisotropy coefficient and thermal heterogeneity factor along the cores allowing the high vertical resolution (of up to 1-2 mm). B.fm. rock matrix thermal conductivity was observed to be essentially stable within the range of 2.5-2.7 W/(m*K). However, stable matrix thermal conductivity along with the high thermal anisotropy coefficient is characteristic for B.fm. sediments due to the low rock porosity values. It is shown experimentally that thermal parameters measured relate linearly to organic richness rather than to porosity coefficient deviations. Thus, a new technique employing the transformation of the thermal conductivity profiles into continuous profiles of total organic carbon (TOC) values along the core was developed. Comparison of TOC values, estimated from the thermal conductivity values, with experimental pyrolytic TOC estimations of 665 samples from the cores using the Rock-Eval and HAWK instruments demonstrated high efficiency of the new technique for the organic rich intervals separation. The data obtained with the new technique are essential for the SR hydrocarbon generation potential, for basin and petroleum system modeling application, and estimation of hydrocarbon reserves. The method allows for the TOC richness to be accurately assessed using the thermal well logs. The research work was done with financial support of the Russian Ministry of Education and Science (unique identification number RFMEFI58114X0008).

  9. The Evaluation of Land Ecological Safety of Chengchao Iron Mine Based on PSR and MEM

    Science.gov (United States)

    Jin, Xiangdong; Chen, Yong

    2018-01-01

    Land ecological security is of vital importance to local security and sustainable development of mining activities. The study has analyzed the potential causal chains between the land ecological security of Iron Mine mining environment, mine resource and the social-economic background. On the base of Pressure-State-Response model, the paper set up a matter element evaluation model of land ecological security, and applies it in Chengchao iron mine. The evaluation result proves to be effective in land ecological evaluation.

  10. Comparison between traditional laboratory tests, permeability measurements and CT-based fluid flow modelling for cultural heritage applications

    Energy Technology Data Exchange (ETDEWEB)

    De Boever, Wesley, E-mail: Wesley.deboever@ugent.be [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281, 9000 Ghent (Belgium); Bultreys, Tom; Derluyn, Hannelore [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281, 9000 Ghent (Belgium); Van Hoorebeke, Luc [UGCT/Radiation Physics, Dept. of Physics & Astronomy, Ghent University, Proeftuinstraat 86, 9000 Ghent (Belgium); Cnudde, Veerle [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281, 9000 Ghent (Belgium)

    2016-06-01

    In this paper, we examine the possibility to use on-site permeability measurements for cultural heritage applications as an alternative for traditional laboratory tests such as determination of the capillary absorption coefficient. These on-site measurements, performed with a portable air permeameter, were correlated with the pore network properties of eight sandstones and one granular limestone that are discussed in this paper. The network properties of the 9 materials tested in this study were obtained from micro-computed tomography (μCT) and compared to measurements and calculations of permeability and the capillary absorption rate of the stones under investigation, in order to find the correlation between pore network characteristics and fluid management characteristics of these sandstones. Results show a good correlation between capillary absorption, permeability and network properties, opening the possibility of using on-site permeability measurements as a standard method in cultural heritage applications. - Highlights: • Measurements of capillary absorption are compared to in-situ permeability. • We obtain pore size distribution and connectivity by using micro-CT. • These properties explain correlation between permeability and capillarity. • Correlation between both methods is good to excellent. • Permeability measurements could be a good alternative to capillarity measurement.

  11. Improved Prediction of Blood-Brain Barrier Permeability Through Machine Learning with Combined Use of Molecular Property-Based Descriptors and Fingerprints.

    Science.gov (United States)

    Yuan, Yaxia; Zheng, Fang; Zhan, Chang-Guo

    2018-03-21

    Blood-brain barrier (BBB) permeability of a compound determines whether the compound can effectively enter the brain. It is an essential property which must be accounted for in drug discovery with a target in the brain. Several computational methods have been used to predict the BBB permeability. In particular, support vector machine (SVM), which is a kernel-based machine learning method, has been used popularly in this field. For SVM training and prediction, the compounds are characterized by molecular descriptors. Some SVM models were based on the use of molecular property-based descriptors (including 1D, 2D, and 3D descriptors) or fragment-based descriptors (known as the fingerprints of a molecule). The selection of descriptors is critical for the performance of a SVM model. In this study, we aimed to develop a generally applicable new SVM model by combining all of the features of the molecular property-based descriptors and fingerprints to improve the accuracy for the BBB permeability prediction. The results indicate that our SVM model has improved accuracy compared to the currently available models of the BBB permeability prediction.

  12. Permeability testing of biomaterial membranes

    Energy Technology Data Exchange (ETDEWEB)

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B [NMI Natural and Medical Sciences Institute at University Tuebingen, Markwiesenstr. 55, D-72770 Reutlingen (Germany); Ahlers, M [GELITA AG, Gammelsbacher Str. 2, D-69412 Eberbach (Germany)], E-mail: schlosshauer@nmi.de

    2008-09-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation.

  13. Permeability testing of biomaterial membranes

    International Nuclear Information System (INIS)

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B; Ahlers, M

    2008-01-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation

  14. Non-trivial role of interlayer cation states in iron-based superconductors

    Science.gov (United States)

    Valenti, Roser; Guterding, Daniel; Jeschke, Harald O.; Glasbrenner, J. K.; Bascones, E.; Mazin, I. I.

    Unconventional superconductivity in iron pnictides and chalcogenides has been suggested to be controlled by the interplay of low-energy antiferromagnetic spin fluctuations and the particular topology of the Fermi surface in these materials. Under this assumption, one would expect the large class of isostructural and isoelectronic iron germanide compounds to be good superconductors, but they aren't. In this talk we will argue that superconductivity in iron germanides is suppressed by strong ferromagnetic tendencies, which surprisingly do not originate from changes in bond-angles or bond-distances with respect to iron pnictides, but are due to changes in the electronic structure in a wide range of energies happening upon substitution of atom species (As by Ge and the corresponding spacer cations). We will discuss the implications of these results in the general context of Fe-based superconductors. Funding by the Deutsche Forschungsgemeinschaft is acknowledged.

  15. Vanadium Influence on Iron Based Intermetallic Phases in AlSi6Cu4 Alloy

    Directory of Open Access Journals (Sweden)

    Bolibruchová D.

    2014-10-01

    Full Text Available Negative effect of iron in Al-Si alloys mostly refers with iron based intermetallic phases, especially Al5FeSi phases. These phases are present in platelet-like forms, which sharp edges are considered as main cracks initiators and also as contributors of porosity formation. In recent times, addition of some elements, for example Mn, Co, Cr, Ni, V, is used to reduce influence of iron. Influence of vanadium in aluminium AlSi6Cu4 alloy with intentionally increased iron content is presented in this article. Vanadium amount has been graduated and chemical composition of alloy has been analysed by spectral analysis. Vanadium influence on microstructural changes was evaluated by microstructural analysis and some of intermetallic particles were reviewed by EDX analysis.

  16. Immunological effects of iron oxide nanoparticles and iron-based complex drug formulations: Therapeutic benefits, toxicity, mechanistic insights, and translational considerations.

    Science.gov (United States)

    Shah, Ankit; Dobrovolskaia, Marina A

    2018-04-01

    Nanotechnology offers several advantages for drug delivery. However, there is the need for addressing potential safety concerns regarding the adverse health effects of these unique materials. Some such effects may occur due to undesirable interactions between nanoparticles and the immune system, and they may include hypersensitivity reactions, immunosuppression, and immunostimulation. While strategies, models, and approaches for studying the immunological safety of various engineered nanoparticles, including metal oxides, have been covered in the current literature, little attention has been given to the interactions between iron oxide-based nanomaterials and various components of the immune system. Here we provide a comprehensive review of studies investigating the effects of iron oxides and iron-based nanoparticles on various types of immune cells, highlight current gaps in the understanding of the structure-activity relationships of these materials, and propose a framework for capturing their immunotoxicity to streamline comparative studies between various types of iron-based formulations. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Co-Production of Electricity and Hydrogen Using a Novel Iron-based Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Hilaly, Ahmad; Georgas, Adam; Leboreiro, Jose; Arora, Salil; Head, Megann; Trembly, Jason; Turk, Brian; Gupta, Raghubir

    2011-09-30

    The primary objective of this project was to develop a hydrogen production technology for gasification applications based on a circulating fluid-bed reactor and an attrition resistant iron catalyst. The work towards achieving this objective consisted of three key activities: Development of an iron-based catalyst suitable for a circulating fluid-bed reactor; Design, construction, and operation of a bench-scale circulating fluid-bed reactor system for hydrogen production; Techno-economic analysis of the steam-iron and the pressure swing adsorption hydrogen production processes. This report describes the work completed in each of these activities during this project. The catalyst development and testing program prepared and iron-based catalysts using different support and promoters to identify catalysts that had sufficient activity for cyclic reduction with syngas and steam oxidation and attrition resistance to enable use in a circulating fluid-bed reactor system. The best performing catalyst from this catalyst development program was produced by a commercial catalyst toll manufacturer to support the bench-scale testing activities. The reactor testing systems used during material development evaluated catalysts in a single fluid-bed reactor by cycling between reduction with syngas and oxidation with steam. The prototype SIP reactor system (PSRS) consisted of two circulating fluid-bed reactors with the iron catalyst being transferred between the two reactors. This design enabled demonstration of the technical feasibility of the combination of the circulating fluid-bed reactor system and the iron-based catalyst for commercial hydrogen production. The specific activities associated with this bench-scale circulating fluid-bed reactor systems that were completed in this project included design, construction, commissioning, and operation. The experimental portion of this project focused on technical demonstration of the performance of an iron-based catalyst and a

  18. Avidin-biotin-based approach to forming heterotypic cell clusters and cell sheets on a gas-permeable membrane

    Energy Technology Data Exchange (ETDEWEB)

    Hamon, M; Ozawa, T; Montagne, K; Kojima, N; Ishii, R; Sakai, Y [Institute of Industrial Science (IIS), University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Yamaguchi, S; Nagamune, T [Department of Bioengineering, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ushida, T, E-mail: mzh0026@auburn.edu [Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2011-09-15

    Implantation of sheet-like liver tissues is a promising method in hepatocyte-based therapies, because angiogenesis is expected to occur upon implantation from the surrounding tissues. In this context, we introduce here a new methodology for the formation of a functional thick hepatic tissue usable for cell sheet technology. First, we report the formation of composite tissue elements in suspension culture. Composite elements were composed of human hepatoma Hep G2 cells and mouse NIH/3T3 fibroblasts which are important modulators for thick-tissue formation. To overcome the very low attachment and organization capability between different cells in suspension, we synthesized a new cell-to-cell binding molecule based on the avidin-biotin binding system that we previously applied to attach hepatocytes on artificial substrata. This newly synthesized biotin-conjugated biocompatible anchoring molecule was inserted in the plasma membrane of both cell types. NIH/3T3 cells were further conjugated with avidin and incubated with biotin-presenting Hep G2 cells to form highly composite tissue elements. Then, we seeded those elements on highly gas-permeable membranes at their closest packing density to induce the formation of a thick, composite, functional hepatic tissue without any perfusion. This methodology could open a new way to engineer implantable thick liver tissue sheets where different cell types are spatially organized and well supplied with oxygen.

  19. Tomography based determination of permeability, Dupuit-Forchheimer coefficient, and interfacial heat transfer coefficient in reticulate porous ceramics

    International Nuclear Information System (INIS)

    Petrasch, Joerg; Meier, Fabian; Friess, Hansmartin; Steinfeld, Aldo

    2008-01-01

    A computer tomography based methodology is applied to determine the transport properties of fluid flow across porous media. A 3D digital representation of a 10-ppi reticulate porous ceramic (RPC) sample was generated by X-ray tomographic scans. Structural properties such as the porosity, specific interfacial surface area, pore-size distribution, mean survival time, two-point correlation function s 2 , and local geometry distribution of the RPC sample are directly extracted from the tomographic data. Reference solutions of the fluid flow governing equations are obtained for Re = 0.2-200 by applying finite volume direct pore-level numerical simulation (DPLS) using unstructured, body-fitted, tetrahedral mesh discretization. The permeability and the Dupuit-Forchheimer coefficient are determined from the reference solutions by DPLS, and compared to the values predicted by selected porous media flow models, namely: conduit-flow, hydraulic radius theory, drag models, mean survival time bound, s 2 -bound, fibrous bed correlations, and local porosity theory-based models. DPLS is further employed to determine the interfacial heat transfer coefficient and to derive a corresponding Nu-correlation, which is compared to empirical correlations

  20. Spin dynamics in 122-type iron-based superconductors

    International Nuclear Information System (INIS)

    Park, Jitae

    2012-01-01

    In this thesis, we present the experimental data on four different iron-based SC materials. It is mainly about the magnetic-dynamics study in the FeSC that is assumed to be among the most crucial ingredients for superconductivity in this system. Thus, the main goal of this thesis is to figure out the exact relationship between spin dynamics and superconductivity, and then further to realize what is the contribution of magnetic fluctuations for superconductivity by providing experimental data for modeling a microscopic mechanism of electron pairing in the FeSC system. In Chap. 2, we first discuss basic characteristics of FeSC, such as crystal structure and electron band-structure by briefly reviewing the relevant literature. Then, an introduction about magnetic and SC phases will follow based on the generic phase diagram. Details about current understanding of magnetic ground state in the parent compounds will be discussed in terms of spin-wave excitations which would be important when we are considering the spin dynamics in doped materials. To study magnetic dynamics in FeSC, we employed the inelastic-neutron-scattering (INS) method which can uniquely probe the underlying spin dynamics in the four dimensional energy and momentum space in a wide range. By taking advantage of the well developed theory for the magnetic neutron-scattering process, one can quantify the imaginary part of spin susceptibility that is an essential physical quantity the description of elementary magnetic excitations and can be compared with theoretical calculations directly. Moreover, the technique's energy-resolving scale spans over the most relevant energy range of magnetic fluctuations (from 0 to 100 meV). For these reasons, neutron scattering is a very powerful technique for magnetism study, and we introduce how neutron-scattering experiment works theoretically and practically in Chap. 3. For a slightly underdoped Ba 1-x K x Fe 2 As 2 compound, we report the phase separation between

  1. Spin dynamics in 122-type iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jitae

    2012-07-16

    In this thesis, we present the experimental data on four different iron-based SC materials. It is mainly about the magnetic-dynamics study in the FeSC that is assumed to be among the most crucial ingredients for superconductivity in this system. Thus, the main goal of this thesis is to figure out the exact relationship between spin dynamics and superconductivity, and then further to realize what is the contribution of magnetic fluctuations for superconductivity by providing experimental data for modeling a microscopic mechanism of electron pairing in the FeSC system. In Chap. 2, we first discuss basic characteristics of FeSC, such as crystal structure and electron band-structure by briefly reviewing the relevant literature. Then, an introduction about magnetic and SC phases will follow based on the generic phase diagram. Details about current understanding of magnetic ground state in the parent compounds will be discussed in terms of spin-wave excitations which would be important when we are considering the spin dynamics in doped materials. To study magnetic dynamics in FeSC, we employed the inelastic-neutron-scattering (INS) method which can uniquely probe the underlying spin dynamics in the four dimensional energy and momentum space in a wide range. By taking advantage of the well developed theory for the magnetic neutron-scattering process, one can quantify the imaginary part of spin susceptibility that is an essential physical quantity the description of elementary magnetic excitations and can be compared with theoretical calculations directly. Moreover, the technique's energy-resolving scale spans over the most relevant energy range of magnetic fluctuations (from 0 to 100 meV). For these reasons, neutron scattering is a very powerful technique for magnetism study, and we introduce how neutron-scattering experiment works theoretically and practically in Chap. 3. For a slightly underdoped Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} compound, we report the phase

  2. Corrosion modelling of iron based alloy in nuclear waste repository

    Energy Technology Data Exchange (ETDEWEB)

    Bataillon, C., E-mail: christian.bataillon@cea.f [CEA, DEN, DPC, SCCME, F-91191 Gif sur Yvette (France); Bouchon, F.; Chainais-Hillairet, C. [Clermont Universite, Universite Blaise Pascal, Laboratoire de Mathematiques, BP10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6620, Laboratoire de Mathematiques, F-63177 Aubiere (France); Desgranges, C. [CEA, DEN, DPC, SCCME, F-91191 Gif sur Yvette (France); Hoarau, E. [ANDRA/DS, 92298 Chatenay-Malabry Cedex (France); Martin, F.; Perrin, S. [CEA, DEN, DPC, SCCME, F-91191 Gif sur Yvette (France); Tupin, M. [CEA, DEN, DMN, SEMI, LM2E, F-91191 Gif sur Yvette (France); Talandier, J. [ANDRA/DS, 92298 Chatenay-Malabry Cedex (France)

    2010-06-01

    The Diffusion Poisson Coupled Model (DPCM) is presented to modelling the oxidation of a metal covered by an oxide layer. This model is similar to the Point Defect Model and the Mixed Conduction Model except for the potential profile which is not assumed but calculated in solving the Poisson equation. This modelling considers the motions of two moving interfaces linked through the ratio of Pilling-Bedworth. Their locations are unknowns of the model. Application to the case of iron in neutral or slightly basic solution is discussed. Then, DPCM has been first tested in a simplified situation where the locations of interfaces were fixed. In such a situation, DPCM is in agreement with Mott-Schottky model when iron concentration profile is homogeneous. When it is not homogeneous, deviation from Mott-Schottky model has been observed and is discussed. The influence of the outer and inner interfacial structures on the kinetics of electrochemical reactions is illustrated and discussed. Finally, simulations for the oxide layer growth are presented. The expected trends have been obtained. The steady-state thickness is a linear function of the applied potential and the steady-state current density is potential independent.

  3. Dimensional crossover in manganese based analogues of iron pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Zingl, Manuel; Assmann, Elias; Aichhorn, Markus [University of Technology, Institute of Theoretical Physics and Computational Physics, Graz (Austria)

    2016-07-01

    The manganese pnicitides BaMn{sub 2}As{sub 2} and LaOMnAs crystallize in the same structure as the extensively studied iron pnictide high-temperature superconductors BaFe{sub 2}As{sub 2} and LaOFeAs. In contrast to the d{sup 6} configuration of the iron systems, the manganese d-shell is only half-filled (d{sup 5}). As a consequence, electronic correlations are much stronger, placing these compounds at the verge of the Mott metal-insulator transition. In this region of the phase diagram materials are prone to enhanced magnetism, apparent in the remarkably high Neel temperature of 625 K for BaMn{sub 2}As{sub 2}. We demonstrate that the experimentally observed differences in the Neel temperatures, the band gap, and the optical properties of the manganese compounds under consideration can be traced back to their effective dimensionality. Our fully charge self-consistent DFT+DMFT calculations show excellent agreement with experiments, especially measured optical spectra.

  4. Nitrogen Cycling in Permeable Sediments: Process-based Models for Streams and the Coastal Ocean

    OpenAIRE

    Azizian, Morvarid

    2017-01-01

    Bioavailable forms of nitrogen, such as nitrate, are necessary for aquatic ecosystem productivity. Excess nitrate in aquatic systems, however, can adversely affect ecosystems and degrade both surface water and groundwater. Some of this excess nitrate can be removed in the sediments that line the bottom of rivers and coastal waters, through the exchange of water between surface water and groundwater (known as hyporheic exchange).Several process-based models have been proposed for estimating ni...

  5. Corrosion resistance and electrochemical potentiokinetic reactivation testing of some iron-base hardfacing alloys

    International Nuclear Information System (INIS)

    Cockeram, B.V.

    1999-01-01

    Hardfacing alloys are weld deposited on a base material to provide a wear resistant surface. Commercially available iron-base hardfacing alloys are being evaluated for replacement of cobalt-base alloys to reduce nuclear plant activation levels. Corrosion testing was used to evaluate the corrosion resistance of several iron-base hardfacing alloys in highly oxygenated environments. The corrosion test results indicate that iron-base hardfacing alloys in the as-deposited condition have acceptable corrosion resistance when the chromium to carbon ratio is greater than 4. Tristelle 5183, with a high niobium (stabilizer) content, did not follow this trend due to precipitation of niobium-rich carbides instead of chromium-rich carbides. This result indicates that iron-base hardfacing alloys containing high stabilizer contents may possess good corrosion resistance with Cr:C < 4. NOREM 02, NOREM 01, and NoCo-M2 hardfacing alloys had acceptable corrosion resistance in the as-deposited and 885 C/4 hour heat treated condition, but rusting from sensitization was observed in the 621 C/6 hour heat treated condition. The feasibility of using an Electrochemical Potentiokinetic Reactivation (EPR) test method, such as used for stainless steel, to detect sensitization in iron-base hardfacing alloys was evaluated. A single loop-EPR method was found to provide a more consistent measurement of sensitization than a double loop-EPR method. The high carbon content that is needed for a wear resistant hardfacing alloy produces a high volume fraction of chromium-rich carbides that are attacked during EPR testing. This results in inherently lower sensitivity for detection of a sensitized iron-base hardfacing alloy than stainless steel using conventional EPR test methods

  6. Virtual iron concentration imaging based on dual-energy CT for noninvasive quantification and grading of liver iron content: An iron overload rabbit model study

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian Fu; Yang, Yi; Xie, Xue Qian; Zhang, Huan; Chai, Wei Min; Yan, Fu Hua [Shanghai Jiao Tong University School of Medicine, Department of Radiology, Ruijin Hospital, Shanghai (China); Yan, Jing [Siemens Shanghai Medical Equipment Ltd., Shanghai (China); Wang, Li [Fudan University, Center of Analysis and Measurement, Shanghai (China); Schmidt, Bernhard [Siemens AG, Healthcare Sector, Forchheim (Germany)

    2015-09-15

    To assess the accuracy of liver iron content (LIC) quantification and grading ability associated with clinical LIC stratification using virtual iron concentration (VIC) imaging on dual-energy CT (DECT) in an iron overload rabbit model. Fifty-one rabbits were prepared as iron-loaded models by intravenous injection of iron dextran. DECT was performed at 80 and 140 kVp. VIC images were derived from an iron-specific algorithm. Postmortem LIC assessments were conducted on an inductively coupled plasma (ICP) spectrometer. Correlation between VIC and LIC was analyzed. VIC were stratified according to the corresponding clinical LIC thresholds of 1.8, 3.2, 7.0, and 15.0 mg Fe/g. Diagnostic performance of stratification was evaluated by receiver operating characteristic analysis. VIC linearly correlated with LIC (r = 0.977, P < 0.01). No significant difference was observed between VIC-derived LICs and ICP (P > 0.05). For the four clinical LIC thresholds, the corresponding cutoff values of VIC were 19.6, 25.3, 36.9, and 61.5 HU, respectively. The highest sensitivity (100 %) and specificity (100 %) were achieved at the threshold of 15.0 mg Fe/g. Virtual iron concentration imaging on DECT showed potential ability to accurately quantify and stratify hepatic iron accumulation in the iron overload rabbit model. (orig.)

  7. Mineralogy, geochemistry and origin of Zafarabad iron deposit based on REE and trace elements of magnetite

    Directory of Open Access Journals (Sweden)

    Mehrdad Barati

    2013-10-01

    Full Text Available Zafarabad iron deposit is located northwest of Divandareh, in the northern margin of Sanandaj-Sirjan plutonic-metamorphic zone. The deposit is in lentoid to tubular shape, within a shear zone and occrrued in host rocks of calc-schist and limestone. Magnetite with massive, cataclastic and replacement textures are the main phases, while pyrite and other sulfide minerals are found. Major and trace elements are measured by ICP-MS and ICP-AES methods. Based on some ratios of trace elements in the ore samples and (Ti+V vs. Cal+Al+Mn and Ti+V vs. Ni/(Cr+Mn diagrams which are used for classification of iron deposit types, Zafarabad iron deposit fall in the range of skarn deposits. Spider diagrams show a steady decline from LREE to HREE elements with Eu (mean value of 0.06 ppm and Ce (mean value of 0.94 ppm negative anomalies. Comparing the distribution patterns of REE for the Zafarabad magnetites with those of various types of iron deposits shows that the REE pattern for Zafarabad is similar to these deposits. Analysis of calculated parameters for REE shows that the hydrothermal fluids responsible for mineralization are mainly of magmatic origin through fractionation and crystallization processes of a deep iron rich fluid phase and its emplacement within the carbonate rocks, forming iron skarn.

  8. Antiferromagnetism and its origin in iron-based superconductors (Review Article)

    International Nuclear Information System (INIS)

    Ding, Ming-Cui; Zhang, Yu-Zhong; Lin, Hai-Qing

    2014-01-01

    In iron-based superconductors, unravelling the origin of the antiferromagnetism is a crucial step towards understanding the high-T c superconductivity as it is widely believed that the magnetic fluctuations play important roles in the formation of the Cooper pairs. Therefore, in this paper, we will briefly review experimental results related to the antiferromagnetic state in iron-based superconductors and focus on a review of the theoretical investigations which show applicability of the itinerant scenario to the observed antiferromagnetism and corresponding phase transitions in various families of the iron-based superconductors. A proposal of coupling between frustrated and un frustrated bands for understanding the reduced magnetic moment typically observed in iron pnictides is also reviewed. While all the above theoretical investigations do not rule out a possible existence of localized electrons in iron-based superconductors, these results strongly indicate a close relation between itinerant electrons and the magnetically ordered state and point out the importance of taking into account the orbital degrees of freedom.

  9. Interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials: A review.

    Science.gov (United States)

    He, Jie; Yang, Xiaofang; Men, Bin; Wang, Dongsheng

    2016-01-01

    The heterogeneous Fenton reaction can generate highly reactive hydroxyl radicals (OH) from reactions between recyclable solid catalysts and H2O2 at acidic or even circumneutral pH. Hence, it can effectively oxidize refractory organics in water or soils and has become a promising environmentally friendly treatment technology. Due to the complex reaction system, the mechanism behind heterogeneous Fenton reactions remains unresolved but fascinating, and is crucial for understanding Fenton chemistry and the development and application of efficient heterogeneous Fenton technologies. Iron-based materials usually possess high catalytic activity, low cost, negligible toxicity and easy recovery, and are a superior type of heterogeneous Fenton catalysts. Therefore, this article reviews the fundamental but important interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials. OH, hydroperoxyl radicals/superoxide anions (HO2/O2(-)) and high-valent iron are the three main types of reactive oxygen species (ROS), with different oxidation reactivity and selectivity. Based on the mechanisms of ROS generation, the interfacial mechanisms of heterogeneous Fenton systems can be classified as the homogeneous Fenton mechanism induced by surface-leached iron, the heterogeneous catalysis mechanism, and the heterogeneous reaction-induced homogeneous mechanism. Different heterogeneous Fenton systems catalyzed by characteristic iron-based materials are comprehensively reviewed. Finally, related future research directions are also suggested. Copyright © 2015. Published by Elsevier B.V.

  10. Risk-Based Questionnaires Fail to Detect Adolescent Iron Deficiency and Anemia.

    Science.gov (United States)

    Sekhar, Deepa L; Murray-Kolb, Laura E; Schaefer, Eric W; Paul, Ian M

    2017-08-01

    To evaluate the predictive ability of screening questionnaires to identify adolescent women at high-risk for iron deficiency or iron deficiency anemia who warrant objective laboratory testing. Cross-sectional study of 96 female individuals 12-21 years old seen at an academic medical center. Participants completed an iron deficiency risk assessment questionnaire including the 4 Bright Futures Adolescent Previsit Questionnaire anemia questions, along with depression, attention, food insecurity, and daytime sleepiness screens. Multiple linear regression controlling for age, race, and hormonal contraception use compared the predictive ability of 2 models for adolescent iron deficiency (defined as ferritin anemia (hemoglobin iron deficiency and 5% (5/96) had iron deficiency anemia. Model 1 (Bright Futures) poorly predicted ferritin and hemoglobin values (R 2  = 0.03 and 0.08, respectively). Model 2 demonstrated similarly poor predictive ability (R 2  = 0.05 and 0.06, respectively). Mean differences for depressive symptoms (0.3, 95% CI -0.2, 0.8), attention difficulty (-0.1, 95% CI -0.5, 0.4), food insecurity (0.04, 95% CI -0.5, 0.6), daytime sleepiness (0.1, 95% CI -0.1, 0.3), and body mass index percentile (-0.04, 95% CI -0.3, 0.2) were not significantly associated with ferritin in model 2. Mean differences for hemoglobin were also nonsignificant. Risk-based surveys poorly predict objective measures of iron status using ferritin and hemoglobin. Next steps are to establish the optimal timing for objective assessment of adolescent iron deficiency and anemia. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. RF plasma nitriding of severely deformed iron-based alloys

    International Nuclear Information System (INIS)

    Ferkel, H.; Glatzer, M.; Estrin, Y.; Valiev, R.Z.; Blawert, C.; Mordike, B.L.

    2003-01-01

    The effect of severe plastic deformation by cold high pressure torsion (HPT) on radio frequency (RF) plasma nitriding of pure iron, as well as St2K50 and X5CrNi1810 steels was investigated. Nitriding was carried out for 3 h in a nitrogen atmosphere at a pressure of 10 -5 bar and temperatures of 350 and 400 deg. C. Nitrided specimens were analysed by scanning electron microscopy (SEM), X-ray diffraction and micro hardness measurements. It was found that HPT enhances the effect of nitriding leading almost to doubling of the thickness of the nitrided layer for pure iron and the high alloyed steel. The largest increase in hardness was observed when HPT was combined with RF plasma nitriding at 350 deg. C. In the case of pure iron, the X-ray diffraction spectra showed the formation of ε and γ' nitrides in the compound layer, with a preferential formation of γ' at the expense of the α-phase at the higher nitriding temperature. The corresponding surface hardness was up to 950 HV0.01. While the HPT-processed St2K50 exhibits both nitride phases after nitriding at 350 deg. C, only the γ'-phase was observed after nitriding at 400 deg. C. A surface hardness of up to 1050 HV0.01 was measured for this steel. The high alloyed steel X5CrNi1810 exhibited the highest increase in surface hardness when HPT was combined with nitriding at 350 deg. C. The surface hardness of this steel was greater than 1400 HV0.025. The XRD analyses indicate the formation of the expanded austenite (S-phase) in the surface layer as a result of RF plasma nitriding. Furthermore, after HPT X5CrNi1810 was transformed completely into deformation martensite which did not transform back to austenite under thermochemical treatment. However, in the case of nitriding of the HPT-processed high alloyed steel at 400 deg. C, the formation of the S-phase was less pronounced. In view of the observed XRD peak broadening, the formation of nitrides, such as e.g. CrN, cannot be ruled out

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

    Science.gov (United States)

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

    2013-03-01

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

  13. Do sediment type and test durations affect results of laboratory-based, accelerated testing studies of permeable pavement clogging?

    Science.gov (United States)

    Nichols, Peter W B; White, Richard; Lucke, Terry

    2015-04-01

    Previous studies have attempted to quantify the clogging processes of Permeable Interlocking Concrete Pavers (PICPs) using accelerated testing methods. However, the results have been variable. This study investigated the effects that three different sediment types (natural and silica), and different simulated rainfall intensities, and testing durations had on the observed clogging processes (and measured surface infiltration rates) of laboratory-based, accelerated PICP testing studies. Results showed that accelerated simulated laboratory testing results are highly dependent on the type, and size of sediment used in the experiments. For example, when using real stormwater sediment up to 1.18 mm in size, the results showed that neither testing duration, nor stormwater application rate had any significant effect on PICP clogging. However, the study clearly showed that shorter testing durations generally increased clogging and reduced the surface infiltration rates of the models when artificial silica sediment was used. Longer testing durations also generally increased clogging of the models when using fine sediment (<300 μm). Results from this study will help researchers and designers better anticipate when and why PICPs are susceptible to clogging, reduce maintenance and extend the useful life of these increasingly common stormwater best management practices. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Determination of hydraulic conductivity coefficient in NSD site, Serpong, based on in-situ permeability test method

    International Nuclear Information System (INIS)

    Heri Syaeful; Sucipta

    2013-01-01

    In line with the increase of amount of radioactive waste, PTLR-BATAN plans to build the Near Surface Disposal (NSD) facility, especially in the preliminary stages is the Demo Plant of NSD facility. NSD is a low to medium level radioactive waste storage concept. Most important aspect in the site study for planning NSD is hydrogeological aspect especially related to the migration of radionuclides to the environment. In the study of radionuclide migration, a preliminary parameter which is required to know is the hydraulic conductivity in order to deliver the soil and rock hydraulic conductivity values in the site then conducted the in-situ permeability test. Based on the test, obtained soil and rock hydraulic conductivity values ranging from 10 -6 to 10 -2 cm/sec. The greatest hydraulic conductivity value located in the gravelly silt soil units which is in the site, constitute as aquifer, with depth ranging from 8 - 24 m, with hydraulic conductivity value reached 10 -2 cm/sec. (author)

  15. Bubble formation upon crystallization of high nitrogen iron base alloys

    International Nuclear Information System (INIS)

    Svyazhin, A.G.; Sivka, E.; Skuza, Z.

    2000-01-01

    A study is made into the conditions of nitrogen bubble formation during crystallization of unalloyed iron, alloys of Fe-O, Fe-O-S systems, steels 1Kh13, 0Kh18N9 and a two-phase Fe-11%Cr-1%Mo-0.2%V steel. It is revealed that the amount of bubbles in a high nitrogen steel casting increases with a degree of nitrogen supersaturation and decreases with a cooling rate growth and with a rise of surfactant concentration in the metal. In sound castings a nitrogen content can be increased due to a cooling rate growth, nitrogen dilution with inert gas, an increase of nitrogen pressure during crystallization as well as due to the introduction of such surfactants as sulphur, selenium, tellurium, tin [ru

  16. Developments in permeable and low permeability barriers

    International Nuclear Information System (INIS)

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

    1997-01-01

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

  17. Predicting the occurrence of iron chlorosis in grapevine with tests based on soil iron forms

    Directory of Open Access Journals (Sweden)

    Isabel Díaz de la Torre

    2010-06-01

    Significance and impact of study: This study has shown the limited usefulness of tests based on the contents and reactivity of the soil carbonate to predict the occurrence of Fe chlorosis in grapevine; tests capable of estimating the contents of the labile soil Fe forms constitute the best alternative.

  18. A Method for Monitoring Iron and Steel Factory Economic Activity Based on Satellites

    Directory of Open Access Journals (Sweden)

    Yi Zhou

    2018-06-01

    Full Text Available The Chinese government has promulgated a de-capacity policy for economic growth and environmental sustainability, especially for the iron and steel industry. With these policies, this study aimed to monitor the economic activities and evaluate the production conditions of an iron and steel factory based on satellites via Landsat-8 Thermal Infrared Sensor (TIRS data and high-resolution images from January 2013 to October 2017, and propel next economic adjustment and environmental protection. Our methods included the construction of a heat island intensity index for an iron and steel factory (ISHII, a heat island radio index for an iron and steel factory (ISHRI and a dense classifying approach to monitor the spatiotemporal changes of the internal heat field of an iron and steel factory. Additionally, we used GF-2 and Google Earth images to identify the main production area, detect facility changes to a factory that alters its heat field and verify the accuracy of thermal analysis in a specific time span. Finally, these methods were used together to evaluate economic activity. Based on five iron and steel factories in the Beijing-Tianjin-Hebei region, when the ISHII curve is higher than the seasonal changes in a time series, production is normal; otherwise, there is a shut-down or cut-back. In the spatial pattern analyses, the ISHRI is large in normal production and decreases when cut-back or shut-down occurs. The density classifying images and high-resolution images give powerful evidence to the above-mentioned results. Finally, three types of economic activities of normal production, shut-down or cut-back were monitored for these samples. The study provides a new perspective and method for monitoring the economic activity of an iron and steel factory and provides supports for sustainable development in China.

  19. Elastic characteristics and microplastic deformation of amorphous alloys on iron base

    International Nuclear Information System (INIS)

    Pol'dyaeva, G.P.; Zakharov, E.K.; Ovcharov, V.P.; Tret'yakov, B.N.

    1983-01-01

    Investigation results of elasticity and microplasticity properties (modulus of normal elasticity E, elasticity limit σsub(0.01) and yield limit σsub(0.2)) of three amorphous alloys on iron base Fe 80 B 20 , Fe 70 Cr 10 B 20 and Fe 70 Cr 5 Ni 5 B 20 are given. Amorphous band of the alloys is obtained using the method of melt hardening. It is shown that amorphous alloys on iron base possess high elasticity and yield limits and hardness and are very perspective for the use as spring materials

  20. Analysis of iron-base alloys by low-wattage glow discharge emission spectrometry

    International Nuclear Information System (INIS)

    Wagatsuma, K.; Hirokawa, K.

    1984-01-01

    Several iron-base alloys were investigated by low-wattage glow discharge emission spectrometry. The emission intensity principally depended on the sputtering parameters of constituent elements in the alloy. However, in the case of chromium, stable and firm oxides formed on the surface influencing the yield of ejected atoms. This paper discusses the relation between the sputtering parameters in Fe-Ni, Fe-Cr, and Fe-Co alloys and their relative emission intensities. Additionally, quantitative analysis was performed for some ternary iron-base alloys and commercial stainless steels with the calibration factors of binary alloy systems

  1. Elastic characteristics and microplastic deformation of amorphous alloys on iron base

    Energy Technology Data Exchange (ETDEWEB)

    Pol' dyaeva, G.P.; Zakharov, E.K.; Ovcharov, V.P.; Tret' yakov, B.N. (Tsentral' nyj Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii, Moscow (USSR))

    1983-01-01

    Investigation results of elasticity and microplasticity properties (modulus of normal elasticity E, elasticity limit sigmasub(0.01) and yield limit sigmasub(0.2)) of three amorphous alloys on iron base Fe/sub 80/B/sub 20/, Fe/sub 70/Cr/sub 10/B/sub 20/ and Fe/sub 70/Cr/sub 5/Ni/sub 5/B/sub 20/ are given. Amorphous band of the alloys is obtained using the method of melt hardening. It is shown that amorphous alloys on iron base possess high elasticity and yield limits and hardness and are very perspective for the use as spring materials.

  2. Determination of trace impurities in iron-based alloy using neutron activation analysis

    International Nuclear Information System (INIS)

    Zaidi, J.H.; Waheed, S.; Ahmad, S.

    2000-01-01

    A radiochemical neutron activation analysis procedure has been developed and applied to investigate 40 major, minor, and trace impurities in iron-based alloy. A comparison of RNAA and INAA indicated a significant improvement in the detection limits. The extensive use of these alloys in the heavy mechanical industry, manufacturing of aircraft engines, nuclear applications, medical devices and chemical equipment requires their precise characterization. The concentration of iron in the iron-based alloy was found to be 86.7%, whereas Ca, Cr, K, Mg, Mn, V and W were the other constituents of the alloy, which constituted to around 12.89%. The rest of the elements were present in minor or trace levels. Most of the rare earth elements were also present in trace amounts. (orig.)

  3. Low Permeability Polyimide Insulation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Resodyn Technologies proposes a new technology that enables the application of polyimide based cryogenic insulation with low hydrogen permeability. This effort...

  4. Segmentation of the potential consumers of ferric medicines based on data of iron deficiency anemia prevalence

    Directory of Open Access Journals (Sweden)

    Z. N. Mnushko

    2013-08-01

    Full Text Available INTRODUCTION. According to WHO 3.6 billion of people on the planet have latent iron deficiency and another 1.8 billion of people suffer from iron deficiency anemia (IDA. According to the Ministry of Health of Ukraine information the prevalence and the incidence of iron deficiency anemia is 1163.9 and 404.5 per 100 000 persons, respectively. However, this information is only clinically confirmed cases of IDA. The largest share in the structure of morbidity has the latent iron deficiency, which is characterized by less prominent clinical manifestations. Treatment of IDA aimed not only at addressing anemia as a symptom, but also at the elimination of iron deficiency and replenishment of its reserves in the organism, which can be achieved by taking ferric drugs. Today ferric drugs market is characterized by high leveled competition, stable demand and a wide range of products. Therefore, an important issue in the study of the market is to find the best ways to determining its potential capacity to expand the marketing potential and to provide iron supplementation as many consumers who need treatment and prevention of iron deficiency. GOAL OF THE STUDY. the segmentation of the population that needs treatment and prevention of iron deficiency on the basis of the etiological factors that cause development of anemia, based on official statistics on morbidity. MATERIALS AND METODS. According to the standard classification of the iron deficiency we have identified four main groups of etiological factors that lead to the development of IDA: bleeding, iron malabsorption, increased body's need for iron, as well as complicated genesis factors. In order to determine the total number of individual segments we have analyzed the reports of the State Statistics Committee of Ukraine, Health Statistics Centre of Ministry of Health of Ukraine, as well as electronic database of medical statistics “Health for All”. RESULTS AND DISCUSSION. According to the estimates

  5. The impact of a meat- versus a vegetable-based diet on iron status in women of childbearing age with small iron stores

    DEFF Research Database (Denmark)

    Tetens, Inge; Bendtsen, K.M.; Henriksen, M.

    2007-01-01

    about dietary intake before and during intervention, meat/fish intake, menstruation and contraceptive methods were recorded. Results: The women who consumed the meat-based diet had a significantly (P ... on iron status of women of childbearing age. Methods: For 20 weeks, 57 women aged 19-39 years with low iron stores (serum ferritin = 120 g/l) consumed either a meat-based or a vegetable-based diet. Haemoglobin and serum ferritin concentrations were measured at baseline, after 10 and 20 weeks. Information...

  6. Sodium butyrate attenuates soybean oil-based lipid emulsion-induced increase in intestinal permeability of lipopolysaccharide by modulation of P-glycoprotein in Caco-2 cells

    International Nuclear Information System (INIS)

    Yan, Jun-Kai; Gong, Zi-Zhen; Zhang, Tian; Cai, Wei

    2017-01-01

    Down-regulation of intestinal P-glycoprotein (P-gp) by soybean oil-based lipid emulsion (SOLE) may cause elevated intestinal permeability of lipopolysaccharide (LPS) in patients with total parenteral nutrition, but the appropriate preventative treatment is currently limited. Recently, sodium butyrate (NaBut) has been demonstrated to regulate the expression of P-gp. Therefore, this study aimed to address whether treatment with NaBut could attenuate SOLE-induced increase in intestinal permeability of LPS by modulation of P-gp in vitro. Caco-2 cells were exposed to SOLE with or without NaBut. SOLE-induced down-regulation of P-gp was significantly attenuated by co-incubation with NaBut. Nuclear recruitment of FOXO 3a in response to NaBut was involved in P-gp regulation. Transport studies revealed that SOLE-induced increase in permeability of LPS was significantly attenuated by co-incubation with NaBut. Collectively, our results suggested that NaBut may be a potentially useful medication to prevent SOLE-induced increase in intestinal permeability of LPS. - Highlights: • Caco-2 cells were used as models for studying parenteral nutrition in vitro. • NaBut restored SOLE-induced down-regulation of P-gp in Caco-2 cells. • Regulation of P-gp by NaBut was mediated via nuclear recruitment of FOXO 3a. • NaBut modulated the permeability of LPS by P-gp function, not barrier function.

  7. Optical fiber chemiluminescence sensor for iron (II) ion based on immobilized luminol

    International Nuclear Information System (INIS)

    Alipao, Arthur A.; Sevilla, Fortunato III.

    1999-01-01

    A chemiluminescence (CL) sensor for iron (II) was developed based on the catalytic action of the analyte on the CL reaction between luminol and oxygen. The reagents were immobilized on a cellulose membrane and set on a reaction cell which was coupled by means of an optical fiber to a spectrofluorometer. The concentration of iron(II) was quantified by measuring the intensity of the light generated from the CL reaction. The response of the sensor system was rapid and highly reproducible. Good sensitivity was displayed by the sensor system over the five orders of magnitude of iron(II) ion concentration. The calibration curve consisted of two portions: (1) a linear range at lower concentrations (7.5 x 10 -7 M to 1.0 x 10 -4 M) exhibiting a positive slope arising from a catalytic action, and (2) a linear range at higher concentrations (5.0 x 10 -2 M to 2.5 x 10 -4 M) wherein the slope is negative due to an inhibitory action of iron(II) on the CL reaction. The sensor system was highly selective for iron(II) ions. (Author)

  8. Comparison of Iron and Tungsten Based Oxygen Carriers for Hydrogen Production Using Chemical Looping Reforming

    Science.gov (United States)

    Khan, M. N.; Shamim, T.

    2017-08-01

    Hydrogen production by using a three reactor chemical looping reforming (TRCLR) technology is an innovative and attractive process. Fossil fuels such as methane are the feedstocks used. This process is similar to a conventional steam-methane reforming but occurs in three steps utilizing an oxygen carrier. As the oxygen carrier plays an important role, its selection should be done carefully. In this study, two oxygen carrier materials of base metal iron (Fe) and tungsten (W) are analysed using a thermodynamic model of a three reactor chemical looping reforming plant in Aspen plus. The results indicate that iron oxide has moderate oxygen carrying capacity and is cheaper since it is abundantly available. In terms of hydrogen production efficiency, tungsten oxide gives 4% better efficiency than iron oxide. While in terms of electrical power efficiency, iron oxide gives 4.6% better results than tungsten oxide. Overall, a TRCLR system with iron oxide is 2.6% more efficient and is cost effective than the TRCLR system with tungsten oxide.

  9. Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakar, Nirmal, E-mail: nirmalprabhakar@gmail.com; Thakur, Himkusha; Bharti, Anu; Kaur, Navpreet

    2016-10-05

    An electrochemical aptasensor based on chitosan-iron oxide nanocomposite (CHIT-IO) film deposited on fluorine tin Oxide (FTO) was developed for the detection of malathion. Iron oxide nanoparticles were prepared by co-precipitation method and characterized by Transmission electron microscopy and UV–Visible spectroscopy. The biotinylated DNA aptamer sequence specific to the malathion was immobilized onto the iron oxide doped-chitosan/FTO electrode by using streptavidin as linking molecule. Various characterization studies like Field Emission-Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Electrochemical studies were performed to attest the successful fabrication of bioelectrodes. Experimental parameters like aptamer concentration, response time, stability of electrode and reusability studies were optimized. Aptamer immobilized chitosan-iron oxide nanocomposite (APT/SA/CHIT-IO/FTO) bioelectrodes exhibited LOD of about 0.001 ng/mL within 15 min and spike-in studies revealed about 80–92% recovery of malathion from the lettuce leaves and soil sample. - Highlights: • An electrochemical aptasensor for the detection of Malathion has been developed. • Chitosan-iron oxide NP deposited FTO sheets provides platform for aptamer immobilization. • Aptasensor has efficiency to detect malathion upto 0.001 ng/mL within 15 min.

  10. Permeability of cork to gases.

    Science.gov (United States)

    Faria, David P; Fonseca, Ana L; Pereira, Helen; Teodoro, Orlando M N D

    2011-04-27

    The permeability of gases through uncompressed cork was investigated. More than 100 samples were assessed from different plank qualities to provide a picture of the permeability distribution. A novel technique based on a mass spectrometer leak detector was used to directly measure the helium flow through the central area of small disks 10 mm in diameter and 2 mm thick. The permeability for nitrogen, oxygen, and other gases was measured by the pressure rise technique. Boiled and nonboiled cork samples from different sections were evaluated. An asymmetric frequency distribution ranging 3 orders of magnitude (roughly from 1 to 1000 μmol/(cm·atm·day)) for selected samples without macroscopic defects was found, having a peak below 100 μmol/(cm·atm·day). Correlation was found between density and permeability: higher density samples tend to show lower permeability. However, boiled cork showed a mean lower permeability despite having a lower density. The transport mechanism of gases through cork was also examined. Calculations suggest that gases permeate uncompressed cork mainly through small channels between cells under a molecular flow regime. The diameter of such channels was estimated to be in the range of 100 nm, in agreement with the plasmodesmata size in the cork cell walls.

  11. Supercapacitors based on graphene-supported iron nanosheets as negative electrode materials.

    Science.gov (United States)

    Long, Conglai; Wei, Tong; Yan, Jun; Jiang, Lili; Fan, Zhuangjun

    2013-12-23

    We report a facile strategy to prepare iron nanosheets directly grown on graphene sheets nanocomposite (C-PGF) through the carbonization of iron ions adsorbed onto polyaniline nanosheet/graphene oxide hybrid material. Because of the synergistic effect of iron nanosheets and graphene sheets, the as-obtained C-PGF exhibits an ultrahigh capacitance of ca. 720 F g(-1) in 6 M KOH aqueous solution. Additionally, the assembled asymmetric supercapacitor (C-PGF//Ni(OH)2/CNTs) delivers a remarkable high power density and a noticeable ultrahigh energy density of ca. 140 Wh kg(-1) (based on the total mass of active materials) and an acceptable cycling performance of 78% retention after 2000 cycles. Therefore, the designed supercapacitors with high energy density, comparable to rechargeable lithium-ion batteries (LIBs), offer an important guideline for future design of advanced next-generation supercapacitors for both industrial and consumer applications.

  12. Synthesis and characterization of homogeneous interstitial solutions of nitrogen and carbon in iron-based lattices

    DEFF Research Database (Denmark)

    Brink, Bastian Klüge

    work in synthesis and characterization of interstitial solutions ofnitrogen and carbon in iron-based lattices. In order to avoid the influences of gradients incomposition and residual stresses, which are typically found in treated surface layers,homogenous samples are needed. These were prepared from...

  13. The renaissance of iron-based Fischer–Tropsch synthesis: on the multifaceted catalyst deactivation behaviour

    NARCIS (Netherlands)

    de Smit, E.|info:eu-repo/dai/nl/304824232; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2008-01-01

    Iron-based Fischer–Tropsch catalysts, which are applied in the conversion of CO and H2 into longer hydrocarbon chains, are historically amongst the most intensively studied systems in heterogeneous catalysis. Despite this, fundamental understanding of the complex and dynamic chemistry of the

  14. Iron Oxide Nanoparticle-Based Magnetic Ink Development for Fully Printed Tunable Radio-Frequency Devices

    KAUST Repository

    Vaseem, Mohammad

    2018-01-30

    The field of printed electronics is still in its infancy and most of the reported work is based on commercially available nanoparticle-based metallic inks. Although fully printed devices that employ dielectric/semiconductor inks have recently been reported, there is a dearth of functional inks that can demonstrate controllable devices. The lack of availability of functional inks is a barrier to the widespread use of fully printed devices. For radio-frequency electronics, magnetic materials have many uses in reconfigurable components but rely on expensive and rigid ferrite materials. A suitable magnetic ink can facilitate the realization of fully printed, magnetically controlled, tunable devices. This report presents the development of an iron oxide nanoparticle-based magnetic ink. First, a tunable inductor is fully printed using iron oxide nanoparticle-based magnetic ink. Furthermore, iron oxide nanoparticles are functionalized with oleic acid to make them compatible with a UV-curable SU8 solution. Functionalized iron oxide nanoparticles are successfully embedded in the SU8 matrix to make a magnetic substrate. The as-fabricated substrate is characterized for its magnetostatic and microwave properties. A frequency tunable printed patch antenna is demonstrated using the magnetic and in-house silver-organo-complex inks. This is a step toward low-cost, fully printed, controllable electronic components.

  15. Modification of fuel performance code to evaluate iron-based alloy behavior under LOCA scenario

    Energy Technology Data Exchange (ETDEWEB)

    Giovedi, Claudia; Martins, Marcelo Ramos, E-mail: claudia.giovedi@labrisco.usp.br, E-mail: mrmartin@usp.br [Laboratorio de Analise, Avaliacao e Gerenciamento de Risco (LabRisco/POLI/USP), São Paulo, SP (Brazil); Abe, Alfredo; Muniz, Rafael O.R.; Gomes, Daniel de Souza; Silva, Antonio Teixeira e, E-mail: ayabe@ipen.br, E-mail: dsgomes@ipen.br, E-mail: teixiera@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    Accident tolerant fuels (ATF) has been studied since the Fukushima Daiichi accident in the research efforts to develop new materials which under accident scenarios could maintain the fuel rod integrity for a longer period compared to the cladding and fuel system usually utilized in Pressurized Water Reactors (PWR). The efforts have been focused on new materials applied as cladding, then iron-base alloys appear as a possible candidate. The aim of this paper is to implement modifications in a fuel performance code to evaluate the behavior of iron based alloys under Loss-of-Coolant Accident (LOCA) scenario. For this, initially the properties related to the thermal and mechanical behavior of iron-based alloys were obtained from the literature, appropriately adapted and introduced in the fuel performance code subroutines. The adopted approach was step by step modifications, where different versions of the code were created. The assessment of the implemented modification was carried out simulating an experiment available in the open literature (IFA-650.5) related to zirconium-based alloy fuel rods submitted to LOCA conditions. The obtained results for the iron-based alloy were compared to those obtained using the regular version of the fuel performance code for zircaloy-4. The obtained results have shown that the most important properties to be changed are those from the subroutines related to the mechanical properties of the cladding. The results obtained have shown that the burst is observed at a longer time for fuel rods with iron-based alloy, indicating the potentiality of this material to be used as cladding with ATF purposes. (author)

  16. Modification of fuel performance code to evaluate iron-based alloy behavior under LOCA scenario

    International Nuclear Information System (INIS)

    Giovedi, Claudia; Martins, Marcelo Ramos; Abe, Alfredo; Muniz, Rafael O.R.; Gomes, Daniel de Souza; Silva, Antonio Teixeira e

    2017-01-01

    Accident tolerant fuels (ATF) has been studied since the Fukushima Daiichi accident in the research efforts to develop new materials which under accident scenarios could maintain the fuel rod integrity for a longer period compared to the cladding and fuel system usually utilized in Pressurized Water Reactors (PWR). The efforts have been focused on new materials applied as cladding, then iron-base alloys appear as a possible candidate. The aim of this paper is to implement modifications in a fuel performance code to evaluate the behavior of iron based alloys under Loss-of-Coolant Accident (LOCA) scenario. For this, initially the properties related to the thermal and mechanical behavior of iron-based alloys were obtained from the literature, appropriately adapted and introduced in the fuel performance code subroutines. The adopted approach was step by step modifications, where different versions of the code were created. The assessment of the implemented modification was carried out simulating an experiment available in the open literature (IFA-650.5) related to zirconium-based alloy fuel rods submitted to LOCA conditions. The obtained results for the iron-based alloy were compared to those obtained using the regular version of the fuel performance code for zircaloy-4. The obtained results have shown that the most important properties to be changed are those from the subroutines related to the mechanical properties of the cladding. The results obtained have shown that the burst is observed at a longer time for fuel rods with iron-based alloy, indicating the potentiality of this material to be used as cladding with ATF purposes. (author)

  17. Rapid small intestinal permeability assay based on riboflavin and lactulose detected by bis-boronic acid appended benzyl viologens.

    Science.gov (United States)

    Resendez, Angel; Abdul Halim, Md; Landhage, Caroline M; Hellström, Per M; Singaram, Bakthan; Webb, Dominic-Luc

    2015-01-15

    Although organoboronic acids are efficient high-throughput sugar sensors, they have not been pursued for gut permeability studies. A modification of the lactulose/mannitol assay is described by which small intestinal permeability is assessed at the time of urine collection using a lactulose/riboflavin ratio. Volunteers ingested 50mg riboflavin and either 5 g mannitol or 10 g lactulose. Urine was collected for 6 hrs. Riboflavin was assayed by autofluorescence. Riboflavin was removed by C18 solid phase extraction. Lactulose and mannitol were then assayed using 1,1'-bis(2-boronobenzyl)-4,4'-bipyridinium (4,4'oBBV) coupled to the fluorophore HPTS. The temporal profile over 6 hrs for riboflavin paralleled mannitol. Riboflavin recovery in urine was 11.1 ± 1.9 % (mean ± SEM, n=7), similar to mannitol. There was selective binding of 4,4'oBBV to lactulose, likely involving cooperativity between the fructose and galactose moieties. Lower limits of detection and quantification were 90 and 364 μM. The lactulose assay was insensitive to other permeability probes (e.g., sucrose, sucralose) while tolerating glucose or lactose. This assay can be adapted to automated systems. Stability of 4,4'oBBV exceeds 4 years. Riboflavin measured by autofluorescence combined with lactulose measured with 4,4'oBBV represents a useful new chemistry for rapid measurement of intestinal permeability with excellent stability, cost and throughput benefits. Copyright © 2014. Published by Elsevier B.V.

  18. Very heavy iron-punching concretes; Betons tres lourds a base de riblons

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1966-07-01

    The present report deals with all the heavy iron-punching concretes, metallic wastes produced by the transformation industry. After a detailed description of the physical properties of metallic aggregates, a classification of heavy mortars is given, into three main categories: steel-shot grouts d = 5,3 - 6; steel-shot grouts mixed with a mineral d = 3,7 - 4,2; injection heavy grouts d = 3,5 - 4. The following chapter describes iron-punching concretes the most used in the atomic industry: iron-punching concretes mixed with cast-iron - iron-punching concretes mixed with magnetite; iron-punching concretes mixed with barite; iron-punching concretes mixed with limonite; iron-punching concretes mixed with boron. The compositions of these concretes are given together with their physical and mechanical characteristics. Numerous diagrams make it possible to find rapidly the proportions of the constituents of these concretes as a function of the required density. Technical advice and specifications are given in an appendix together with a bibliography of these heavy concretes. (author) [French] Le present rapport traite de l'ensemble des betons lourds realises a l'aide de riblons, dechets metalliques fournis par l'industrie de transformation. Apres une description detaillee des proprietes physiques des agregats metalliques, les mortiers lourds sont d'abord presentes en les classant en trois grandes categories: les mortiers a base de grenailles d 5,3 a 6; les mortiers a base de grenailles avec addition d'un mineral d 3,7 a 4,2; les mortiers lourds injectables d = 3,5 a 4. Le chapitre suivant decrit les betons a base de riblons les plus utilises, dans l'industrie atomique: les betons de riblons avec addition de fonte; les betons de riblons avec addition de magnetite; les betons de riblons avec addition de barytine; les betons de riblons avec addition de limonite; les betons de riblons avec addition de bore. Les compositions de ces betons ainsi que leurs caracteristiques

  19. Very heavy iron-punching concretes; Betons tres lourds a base de riblons

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, F. [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

    1966-07-01

    The present report deals with all the heavy iron-punching concretes, metallic wastes produced by the transformation industry. After a detailed description of the physical properties of metallic aggregates, a classification of heavy mortars is given, into three main categories: steel-shot grouts d = 5,3 - 6; steel-shot grouts mixed with a mineral d = 3,7 - 4,2; injection heavy grouts d = 3,5 - 4. The following chapter describes iron-punching concretes the most used in the atomic industry: iron-punching concretes mixed with cast-iron - iron-punching concretes mixed with magnetite; iron-punching concretes mixed with barite; iron-punching concretes mixed with limonite; iron-punching concretes mixed with boron. The compositions of these concretes are given together with their physical and mechanical characteristics. Numerous diagrams make it possible to find rapidly the proportions of the constituents of these concretes as a function of the required density. Technical advice and specifications are given in an appendix together with a bibliography of these heavy concretes. (author) [French] Le present rapport traite de l'ensemble des betons lourds realises a l'aide de riblons, dechets metalliques fournis par l'industrie de transformation. Apres une description detaillee des proprietes physiques des agregats metalliques, les mortiers lourds sont d'abord presentes en les classant en trois grandes categories: les mortiers a base de grenailles d 5,3 a 6; les mortiers a base de grenailles avec addition d'un mineral d 3,7 a 4,2; les mortiers lourds injectables d = 3,5 a 4. Le chapitre suivant decrit les betons a base de riblons les plus utilises, dans l'industrie atomique: les betons de riblons avec addition de fonte; les betons de riblons avec addition de magnetite; les betons de riblons avec addition de barytine; les betons de riblons avec addition de limonite; les betons de riblons avec addition de bore. Les compositions de ces betons ainsi que

  20. Iron metabolism and toxicity

    International Nuclear Information System (INIS)

    Papanikolaou, G.; Pantopoulos, K.

    2005-01-01

    Iron is an essential nutrient with limited bioavailability. When present in excess, iron poses a threat to cells and tissues, and therefore iron homeostasis has to be tightly controlled. Iron's toxicity is largely based on its ability to catalyze the generation of radicals, which attack and damage cellular macromolecules and promote cell death and tissue injury. This is lucidly illustrated in diseases of iron overload, such as hereditary hemochromatosis or transfusional siderosis, where excessive iron accumulation results in tissue damage and organ failure. Pathological iron accumulation in the liver has also been linked to the development of hepatocellular cancer. Here we provide a background on the biology and toxicity of iron and the basic concepts of iron homeostasis at the cellular and systemic level. In addition, we provide an overview of the various disorders of iron overload, which are directly linked to iron's toxicity. Finally, we discuss the potential role of iron in malignant transformation and cancer

  1. Film Permeability Determination Using Static Permeability Cells

    Science.gov (United States)

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

  2. ARSENIC INTERACTION WITH IRON (II, III) HYDROXYCARBONATE GREEN RUST: IMPLICATIONS FOR ARSENIC REMEDIATION

    Science.gov (United States)

    Zerovalent iron is being used in permeable reactive barriers (PRBs) to remediate groundwater arsenic contamination. Iron(II, III) hydroxycarbonate green rust is a major corrosion product of zerovalent iron under anaerobic conditions. The interaction between arsenic and this green...

  3. Iron-based materials as tar cracking catalyst in waste gasification

    Energy Technology Data Exchange (ETDEWEB)

    Nordgreen, Thomas

    2011-07-01

    The treatment of municipal solid waste (MSW) in Sweden has changed during the past decades due to national legislation and European Union directives. The former landfills have more or less been abandoned in favour of material recycling and waste incineration. On a yearly basis approximately 2.2 million tonnes waste are incinerated in Sweden with heat recovery and to some extent also with electricity generation, though at a low efficiency. It is desirable to alter this utilisation and instead employ MSW as fuel in a fluid bed gasification process. Then electrical energy may be produced at a much higher efficiency. However, MSW contain about 1 % chlorine in the form of ordinary table salt (NaCl) from food scraps. This implies that the tar cracking catalyst, dolomite, which is normally employed in gasification, will suffer from poisoning if applied under such conditions. Then the tar cracking capacity will be reduced or vanish completely with time. Consequently, an alternative catalyst, more resistant to chlorine, is needed. Preliminary research at KTH has indicated that iron in its metallic state may possess tar cracking ability. With this information at hand and participating in the project 'Energy from Waste' an experimental campaign was launched. Numerous experiments were conducted using iron as tar cracking catalyst. First iron sinter pellets from LKAB were employed. They were reduced in situ with a stream of hydrogen before they were applied. Later iron-based granules from Hoeganaes AB were tested. These materials were delivered in the metallic state. In all tests the KTH atmospheric fluidised bed gasifier with a secondary catalytic reactor housing the catalytic material was deployed. Mostly, the applied fuel was birch. The results show that metallic iron possesses an intrinsic ability, almost in the range of dolomite, to crack tars. Calculations indicate that iron may be more resistant to chlorine than dolomite. The exploration of metallic iron

  4. Structure and magnetic properties of iron-based soft magnetic composite with Ni-Cu-Zn ferrite-silicone insulation coating

    Science.gov (United States)

    Li, Wangchang; Wang, Wei; Lv, Junjun; Ying, Yao; Yu, Jing; Zheng, Jingwu; Qiao, Liang; Che, Shenglei

    2018-06-01

    This paper investigates the structure and magnetic properties of Ni-Cu-Zn ferrite-silicone coated iron-based soft magnetic composites (SMCs). Scanning electron microscopy coupled with a energy-dispersive spectroscopy (EDS) analysis revealed that the Ni-Cu-Zn ferrite and silicone resin were uniformly coated on the surface of iron powders. By controlling the composition of the coating layer, low total core loss of 97.7 mW/cm3 (eddy current loss of 48 mW/cm3, hysteresis loss of 49.7 mW/cm3, measured at 100 kHz and 0.02 T) and relatively high effective permeability of 72.5 (measured at 100 kHz) were achieved. In addition, the as-prepared SMCs displayed higher electrical resistivity, good magnetic characteristics over a wide range of frequencies (20-200 kHz) and ideal the D-C bias properties (more than 75% at H = 50 Oe). Furthermore, higher elastic modulus and hardness of SMCs, which means that the coating layer has good mechanical properties and is not easily damaged during the pressing process, were obtained in this paper. The results of this work indicate that the Ni-Cu-Zn ferrite-silicone coated SMCs have desirable properties which would make them suitable for application in the fields of the electric-magnetic switching devices, such as inductance coils, transformer cores, synchronous electric motors and resonant inductors.

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

    Science.gov (United States)

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

    2017-05-01

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

  6. Wastewater engineering applications of BioIronTech process based on the biogeochemical cycle of iron bioreduction and (biooxidation

    Directory of Open Access Journals (Sweden)

    Volodymyr Ivanov

    2014-12-01

    Full Text Available Bioreduction of Fe(III and biooxidation of Fe(II can be used in wastewater engineering as an innovative biotechnology BioIronTech, which is protected for commercial applications by US patent 7393452 and Singapore patent 106658 “Compositions and methods for the treatment of wastewater and other waste”. The BioIronTech process comprises the following steps: 1 anoxic bacterial reduction of Fe(III, for example in iron ore powder; 2 surface renovation of iron ore particles due to the formation of dissolved Fe2+ ions; 3 precipitation of insoluble ferrous salts of inorganic anions (phosphate or organic anions (phenols and organic acids; 4 (biooxidation of ferrous compunds with the formation of negatively, positively, or neutrally charged ferric hydroxides, which are good adsorbents of many pollutants; 5 disposal or thermal regeration of ferric (hydroxide. Different organic substances can be used as electron donors in bioreduction of Fe(III. Ferrous ions and fresh ferrous or ferric hydroxides that are produced after iron bioreduction and (biooxidation adsorb and precipitate diferent negatively charged molecules, for example chlorinated compounds of sucralose production wastewater or other halogenated organics, as well as phenols, organic acids, phosphate, and sulphide. Reject water (return liquor from the stage of sewage sludge dewatering on municipal wastewater treatment plants represents from 10 to 50% of phosphorus load when being recycled to the aeration tank. BioIronTech process can remove/recover more than 90% of phosphorous from this reject water thus replacing the conventional process of phosphate precipitation by ferric/ferrous salts, which are 20–100 times more expensive than iron ore, which is used in BioIronTech process. BioIronTech process can remarkably improve the aerobic and anaerobic treatments of municipal and industrial wastewaters, especially anaerobic digestion of lipid- and sulphate-containing food-processing wastewater. It

  7. 3-D image-based numerical computations of snow permeability: links to specific surface area, density, and microstructural anisotropy

    Directory of Open Access Journals (Sweden)

    N. Calonne

    2012-09-01

    Full Text Available We used three-dimensional (3-D images of snow microstructure to carry out numerical estimations of the full tensor of the intrinsic permeability of snow (K. This study was performed on 35 snow samples, spanning a wide range of seasonal snow types. For several snow samples, a significant anisotropy of permeability was detected and is consistent with that observed for the effective thermal conductivity obtained from the same samples. The anisotropy coefficient, defined as the ratio of the vertical over the horizontal components of K, ranges from 0.74 for a sample of decomposing precipitation particles collected in the field to 1.66 for a depth hoar specimen. Because the permeability is related to a characteristic length, we introduced a dimensionless tensor K*=K/res2, where the equivalent sphere radius of ice grains (res is computed from the specific surface area of snow (SSA and the ice density (ρi as follows: res=3/(SSA×ρi. We define K and K* as the average of the diagonal components of K and K*, respectively. The 35 values of K* were fitted to snow density (ρs and provide the following regression: K = (3.0 ± 0.3 res2 exp((−0.0130 ± 0.0003ρs. We noted that the anisotropy of permeability does not affect significantly the proposed equation. This regression curve was applied to several independent datasets from the literature and compared to other existing regression curves or analytical models. The results show that it is probably the best currently available simple relationship linking the average value of permeability, K, to snow density and specific surface area.

  8. Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening

    International Nuclear Information System (INIS)

    Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C; Konofagou, Elisa E

    2015-01-01

    Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r 2   =  0.77); (2) the permeability of the opened BBB (r 2   =  0.82); (3) the likelihood of safe opening (P  <  0.05, safe opening compared to cases of damage; P  <  0.0001, no opening compared to safe opening). The inertial cavitation dose was correlated with the resulting BBB permeability (r 2   =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response

  9. Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening

    Science.gov (United States)

    Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C.; Konofagou, Elisa E.

    2015-12-01

    Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r2  =  0.77) (2) the permeability of the opened BBB (r2  =  0.82) (3) the likelihood of safe opening (P  cases of damage; P  <  0.0001, no opening compared to safe opening). The inertial cavitation dose was correlated with the resulting BBB permeability (r2  =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response therefore showed great promise in predicting the

  10. Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening.

    Science.gov (United States)

    Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C; Konofagou, Elisa E

    2015-12-07

    Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r(2)  =  0.77); (2) the permeability of the opened BBB (r(2)  =  0.82); (3) the likelihood of safe opening (P  cavitation dose was correlated with the resulting BBB permeability (r(2)  =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response therefore showed great promise in predicting the BBB opening duration, enabling thus control of opening according to the drug

  11. Effect of temperature and relative humidity on the water vapour permeability and mechanical properties of cassava starch and soy protein concentrate based edible films.

    Science.gov (United States)

    Chinma, C E; Ariahu, C C; Alakali, J S

    2015-04-01

    The effect of temperature and relative humidity on the water vapour permeability (WVP) and mechanical properties of cassava starch and soy protein concentrate (SPC) based edible films containing 20 % glycerol level were studied. Tensile strength and elastic modulus of edible films increased with increase in temperature and decreased with increase in relative humidity, while elongation at break decreased. Water vapour permeability of the films increased (2.6-4.3 g.mm/m(2).day.kPa) with increase in temperature and relative humidity. The temperature dependence of water vapour permeation of cassava starch-soy protein concentrate films followed Arrhenius relationship. Activation energy (Ea) of water vapour permeation of cassava starch-soy protein concentrate edible films ranged from 1.9 to 5.3 kJ/mol (R (2)  ≥ 0.93) and increased with increase in SPC addition. The Ea values were lower for the bio-films than for polyvinylidene chloride, polypropylene and polyethylene which are an indication of low water vapour permeability of the developed biofilms compared to those synthetic films.

  12. A study of lattice dynamics in iron-based superconductors by inelastic light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Um, Youngje

    2013-12-13

    After the discovery of high temperature (high T{sub c}) superconductivity in copper oxide-based materials (cuprates) in 1986, this phenomenon was a unique property of the cuprates for more than 20 years. The origin of high T{sub c} superconductivity is still under debate. In 2008, high T{sub c} superconductivity was discovered in iron-based compounds. This discovery presents new opportunities for the development of a fundamental understanding of high T{sub c} superconductivity. Density functional calculations indicate a weak electron-phonon coupling strength in iron-based superconductors and these suggest that superconductivity is not mediated by phonons. However, experimental report of a large isotope effect of the iron atoms on the superconductivity T{sub c} suggests that phonons play an important role in iron-based superconductors. Motivated by these findings, this thesis presents a Raman scattering study of the lattice dynamics of the iron-based superconductors Fe{sub 1+y}Te{sub 1-x}Se{sub x}, LiFeAs and NaFe{sub 1-x}Co{sub x}As as a function of chemical composition and temperature. In Fe{sub 1+y}Te{sub 1-x}Se{sub x}, an unconventional linewidth broadening of the c-axis polarized Fe phonon of B{sub 1g} symmetry is found with decreasing temperature, which indicates an unusual coupling between the phonon and iron excessinduced magnetic fluctuations in this compound. In LiFeAs, the Raman scattering data provide evidence for a weak electron-phonon coupling, which is consistent with non-phonon mediated Cooper pairing in this compound. In NaFe{sub 1-x}Co{sub x}As, upon cooling two features are observed: (i) an unconventional linewidth broadening of several phonons, which is indicative of spin fluctuation-phonon coupling, and (ii) a superconductivity-induced phonon lineshape renormalization, which can not be explained by standard model calculations.

  13. Modelling of water permeability in cementitious materials

    DEFF Research Database (Denmark)

    Guang, Ye; Lura, Pietro; van Breugel, K.

    2006-01-01

    This paper presents a network model to predict the permeability of cement paste from a numerical simulation of its microstructure. Based on a linked list pore network structure, the effective hydraulic conductivity is estimated and the fluid flow is calculated according to the Hagen-Poiseuille law....... The pressure gradient at all nodes is calculated with the Gauss elimination method and the absolute permeability of the pore network is calculated directly from Darcy's law. Finally, the permeability model is validated by comparison with direct water permeability measurements. According to this model...

  14. Thermal behaviour in dynamic recrystallisation. Application for iron base alloys

    International Nuclear Information System (INIS)

    Belkebir, A.; Kobylanski, A.

    1995-01-01

    A constitutive relationship for predicting the flow stress with dynamic recrystallization were proposed. The approach is based on a phenomenological formalism of the law θ-ε where θ correspond to the work-hardening rate at constant strain rate and temperature. The equations proposed were justified by the experimental data collected by hot compression test of low-alloy steels. The model can be used to estimate the critical strain for the onset of dynamic recrystallization. (orig.)

  15. Pure-iron/iron-based-alloy hybrid soft magnetic powder cores compacted at ultra-high pressure

    Science.gov (United States)

    Saito, Tatsuya; Tsuruta, Hijiri; Watanabe, Asako; Ishimine, Tomoyuki; Ueno, Tomoyuki

    2018-04-01

    We developed Fe/FeSiAl soft magnetic powder cores (SMCs) for realizing the miniaturization and high efficiency of an electromagnetic conversion coil in the high-frequency range (˜20 kHz). We found that Fe/FeSiAl SMCs can be formed with a higher density under higher compaction pressure than pure-iron SMCs. These SMCs delivered a saturation magnetic flux density of 1.7 T and iron loss (W1/20k) of 158 kW/m3. The proposed SMCs exhibited similar excellent characteristics even in block shapes, which are closer to the product shapes.

  16. Pure-iron/iron-based-alloy hybrid soft magnetic powder cores compacted at ultra-high pressure

    Directory of Open Access Journals (Sweden)

    Tatsuya Saito

    2018-04-01

    Full Text Available We developed Fe/FeSiAl soft magnetic powder cores (SMCs for realizing the miniaturization and high efficiency of an electromagnetic conversion coil in the high-frequency range (∼20 kHz. We found that Fe/FeSiAl SMCs can be formed with a higher density under higher compaction pressure than pure-iron SMCs. These SMCs delivered a saturation magnetic flux density of 1.7 T and iron loss (W1/20k of 158 kW/m3. The proposed SMCs exhibited similar excellent characteristics even in block shapes, which are closer to the product shapes.

  17. Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor.

    Science.gov (United States)

    Choi, Seokhwan; Choi, Hyoung Joon; Ok, Jong Mok; Lee, Yeonghoon; Jang, Won-Jun; Lee, Alex Taekyung; Kuk, Young; Lee, SungBin; Heinrich, Andreas J; Cheong, Sang-Wook; Bang, Yunkyu; Johnston, Steven; Kim, Jun Sung; Lee, Jhinhwan

    2017-12-01

    We explore a new mechanism for switching magnetism and superconductivity in a magnetically frustrated iron-based superconductor using spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single-crystal Sr_{2}VO_{3}FeAs shows that a spin-polarized tunneling current can switch the Fe-layer magnetism into a nontrivial C_{4} (2×2) order, which cannot be achieved by thermal excitation with an unpolarized current. Our tunneling spectroscopy study shows that the induced C_{4} (2×2) order has characteristics of plaquette antiferromagnetic order in the Fe layer and strongly suppresses superconductivity. Also, thermal agitation beyond the bulk Fe spin ordering temperature erases the C_{4} state. These results suggest a new possibility of switching local superconductivity by changing the symmetry of magnetic order with spin-polarized and unpolarized tunneling currents in iron-based superconductors.

  18. Fuzzy Comprehensive Evaluation of Ecological Risk Based on Cloud Model: Taking Chengchao Iron Mine as Example

    Science.gov (United States)

    Ruan, Jinghua; Chen, Yong; Xiao, Xiao; Yong, Gan; Huang, Ranran; Miao, Zuohua

    2018-01-01

    Aimed at the fuzziness and randomness during the evaluation process, this paper constructed a fuzzy comprehensive evaluation method based on cloud model. The evaluation index system was established based on the inherent risk, present level and control situation, which had been proved to be able to convey the main contradictions of ecological risk in mine on the macro level, and be advantageous for comparison among mines. The comment sets and membership functions improved by cloud model could reflect the uniformity of ambiguity and randomness effectively. In addition, the concept of fuzzy entropy was introduced to further characterize the fuzziness of assessments results and the complexities of ecological problems in target mine. A practical example in Chengchao Iron Mine evidenced that, the assessments results can reflect actual situations appropriately and provide a new theoretic guidance for comprehensive ecological risk evaluation of underground iron mine.

  19. Iron-phosphate-based chemically bonded phosphate ceramics for mixed waste stabilization

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    In an effort to develop chemically bonded phosphate ceramics for mixed waste stabilization, a collaborative project to develop iron-phosphate based ceramics has been initiated between Argonne National Laboratory and the V. G. Khlopin Radium Institute in St. Petersburg, Russia. The starter powders are oxides of iron that are generated as inexpensive byproduct materials in the iron and steel industry. They contain iron oxides as a mixture of magnetite (Fe 3 O 4 ) and haematite (Fe 2 O 3 ). In this initial phase of this project, both of these compounds were investigated independently. Each was reacted with phosphoric acid solution to form iron phosphate ceramics. In the case of magnetite, the reaction was rapid. Adding ash as the waste component containing hazardous contaminants resulted in a dense and hard ceramic rich in glassy phase. On the other hand, the reaction of phosphoric acid solution with a mixture of haematite and ash waste contaminated with cesium and americium was too slow. Samples had to be molded under pressure. They were cured for 2-3 weeks and then hardened by heating at 350 degrees C for 3 h. The resulting ceramics in both cases were subjected to physical tests for measurement of density, open porosity, compression strength, phase analyses using X-ray diffraction and differential thermal analysis, and leaching tests using toxicity characteristic leaching procedure (TCLP) and ANS 16.1 with 7 days of leaching. Using the preliminary information obtained from these tests, we evaluated these materials for stabilization of Department of Energy's mixed waste streams

  20. The Potential for the Treatment of Antimony-Containing Wastewater by Iron-Based Adsorbents

    Directory of Open Access Journals (Sweden)

    Ren-Jian Deng

    2017-10-01

    Full Text Available Antimony (Sb and its compounds are considered as global priority pollutants. Elevated concentrations of antimony in natural and industrial process wastewater are of global concern, particularly given interest in the potential toxicity and harm to the environment from aquatic exposure. Iron-based materials for treatment by adsorption are widely regarded to have potential merit for the removal of trace contaminants from water and especially in the search for efficient and low-cost techniques. In this paper, we review the application of iron-based materials in the sorption treatment of antimony contaminated water. The interaction of Sb is discussed in relation to adsorption performance, influencing factors, mechanism, modelling of adsorption (isotherm, kinetic and thermodynamic models, advantages, drawbacks and the recent achievements in the field. Although iron-based adsorbents show promise, the following three aspects are in need of further study. Firstly, a select number of iron based binary metal oxide adsorbents should be further explored as they show superior performance compared to other systems. Secondly, the possibility of redox reactions and conversion between Sb(III and Sb(V during the adsorption process is unclear and requires further investigation. Thirdly, in order to achieve optimized control of preferential adsorption sites and functional groups, the mechanism of antimony removal has to be qualitatively and quantitatively resolved by combining the advantages of advanced characterization techniques such as Fourier transform infrared spectroscopy(FTIR, X-ray photoelectron spectroscopy (XPS, Atomic force microscope(AFM, X-ray absorption near edge structure(XANES, and other spectroscopic methods. We provide details on the achievements and limitations of each of these stages and point to the need for further research.

  1. Permeability prediction in chalks

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  2. Negative permeability from random particle composites

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-15

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

  3. Antiferroic electronic structure in the nonmagnetic superconducting state of the iron-based superconductors.

    Science.gov (United States)

    Shimojima, Takahiro; Malaeb, Walid; Nakamura, Asuka; Kondo, Takeshi; Kihou, Kunihiro; Lee, Chul-Ho; Iyo, Akira; Eisaki, Hiroshi; Ishida, Shigeyuki; Nakajima, Masamichi; Uchida, Shin-Ichi; Ohgushi, Kenya; Ishizaka, Kyoko; Shin, Shik

    2017-08-01

    A major problem in the field of high-transition temperature ( T c ) superconductivity is the identification of the electronic instabilities near superconductivity. It is known that the iron-based superconductors exhibit antiferromagnetic order, which competes with the superconductivity. However, in the nonmagnetic state, there are many aspects of the electronic instabilities that remain unclarified, as represented by the orbital instability and several in-plane anisotropic physical properties. We report a new aspect of the electronic state of the optimally doped iron-based superconductors by using high-energy resolution angle-resolved photoemission spectroscopy. We find spectral evidence for the folded electronic structure suggestive of an antiferroic electronic instability, coexisting with the superconductivity in the nonmagnetic state of Ba 1- x K x Fe 2 As 2 . We further establish a phase diagram showing that the antiferroic electronic structure persists in a large portion of the nonmagnetic phase covering the superconducting dome. These results motivate consideration of a key unknown electronic instability, which is necessary for the achievement of high- T c superconductivity in the iron-based superconductors.

  4. FEATURES OF SPHEROIDIZING MODIFICATION OF HIGH-STRENGTH CAST IRON WITH MASTER ALLOYS BASED ON COPPER

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2016-01-01

    Full Text Available The increase of efficiency of modification process for ductile iron is topically, thereby increasing its mechanical and operational properties. For these purposes, in practice, various magnesium containing alloys are used, including «heavy» ones on the basis of Copper and Nickel. The analysis has shown that the application of bulk inoculating alloys based on copper basis were not effectively due to long dissolution period. From this point of view, the interest is high-speed casting, allowing the production of inoculating alloys in the form of strips – chips that are characterized by a low dissolution time and low piroeffekt. The aim of this work is to study the features of structure formation in nodular cast iron using different spheroidizing alloys based on copper. Studies have shown that the transition from the use of briquetted form alloys based on copper and magnesium to the «chips-inoculating alloys» allowed increasing the efficiency of the spheroidizing process. Further improvement in the quality of ductile iron can be achieved by the use in «chip-inoculating alloys» additives of nanosized yttrium oxide powder. 

  5. Prevention of blood transfusion with intravenous iron in gynecologic cancer patients receiving platinum-based chemotherapy.

    Science.gov (United States)

    Athibovonsuk, Punnada; Manchana, Tarinee; Sirisabya, Nakarin

    2013-12-01

    To compare the efficacy of intravenous iron and oral iron for prevention of blood transfusions in gynecologic cancer patients receiving platinum-based chemotherapy. Sixty-four non anemic gynecologic cancer patients receiving adjuvant platinum-based chemotherapy were stratified and randomized according to baseline hemoglobin levels and chemotherapy regimen. The study group received 200mg of intravenous iron sucrose immediately after each chemotherapy infusion. The control group received oral ferrous fumarate at a dose of 200mg three times a day. Complete blood count was monitored before each chemotherapy infusion. Blood transfusions were given if hemoglobin level was below 10mg/dl. There were 32 patients in each group. No significant differences in baseline hemoglobin levels and baseline characteristics were demonstrated between both groups. Nine patients (28.1%) in the study group and 18 patients (56.3%) in the control group required blood transfusion through 6 cycles of chemotherapy (p=0.02). Fewer median number of total packed red cell units were required in the study group compared to the control group (0 and 0.5 unit, respectively, p=0.04). Serious adverse events and hypersensitivity reactions were not reported. However, constipation was significantly higher in the control group (3.1% and 40.6%, p=gynecologic cancer patients receiving platinum-based chemotherapy, associated with less constipation than the oral formulation. © 2013 Elsevier Inc. All rights reserved.

  6. Iron based coatings deposited by arc thermal spray

    Directory of Open Access Journals (Sweden)

    Maritza Patiño-Infante

    2017-01-01

    Full Text Available En este trabajo se estudió la resistencia al desgaste y la dureza de recubrimientos a base de hierro, aplicados mediante el método de proyección térmica por arco sobre sustratos en acero AISI-SAE 4340 a temperatura ambiente. Los recubrimientos se realizan con tres tipos diferentes de alambres Castolin Eutectic: 530AS, 560AS y 140MXC; depositados en forma de capas de un solo elemento y bicapas de tipo 530AS/140MXC y 560AS/140MXC, las cuales fueron depositadas con diferentes espesores. Los recubrimientos se caracterizaron mediante difracción de rayos X (DRX, espectroscopia de rayos X de energía dispersiva (EDS, se determinó su nano dureza y se determinó su resistencia al desgaste mediante la técnica de Pin on Disk. Los recubrimientos obtenidos son altamente inhomogéneos, el mejor comportamiento frente al desgaste se encontró en las capas de material 140 MXC y en las bicapas 530AS/140MXC y 560AS/140MXC y fue independiente en general del número de capas aplicadas.

  7. Copper oxide nanoparticles analysis with water as base fluid for peristaltic flow in permeable tube with heat transfer.

    Science.gov (United States)

    Akbar, Noreen Sher; Raza, M; Ellahi, R

    2016-07-01

    The peristaltic flow of a copper oxide water fluid investigates the effects of heat generation and magnetic field in permeable tube is studied. The mathematical formulation is presented, the resulting equations are solved exactly. The obtained expressions for pressure gradient, pressure rise, temperature, velocity profile are described through graphs for various pertinent parameters. It is found that pressure gradient is reduce with enhancement of particle concentration and velocity profile is upturn, beside it is observed that temperature increases as more volume fraction of copper oxide. The streamlines are drawn for some physical quantities to discuss the trapping phenomenon. Copyright © 2016. Published by Elsevier Ireland Ltd.

  8. Identifying the optimal HVOF spray parameters to attain minimum porosity and maximum hardness in iron based amorphous metallic coatings

    Directory of Open Access Journals (Sweden)

    S. Vignesh

    2017-04-01

    Full Text Available Flow based Erosion – corrosion problems are very common in fluid handling equipments such as propellers, impellers, pumps in warships, submarine. Though there are many coating materials available to combat erosion–corrosion damage in the above components, iron based amorphous coatings are considered to be more effective to combat erosion–corrosion problems. High velocity oxy-fuel (HVOF spray process is considered to be a better process to coat the iron based amorphous powders. In this investigation, iron based amorphous metallic coating was developed on 316 stainless steel substrate using HVOF spray technique. Empirical relationships were developed to predict the porosity and micro hardness of iron based amorphous coating incorporating HVOF spray parameters such as oxygen flow rate, fuel flow rate, powder feed rate, carrier gas flow rate, and spray distance. Response surface methodology (RSM was used to identify the optimal HVOF spray parameters to attain coating with minimum porosity and maximum hardness.

  9. Iron oxide-based conjugates for cancer theragnostics

    Science.gov (United States)

    Phuc Nguyen, Xuan; Tran, Dai Lam; Thu Ha, Phuong; Pham, Hong Nam; Trang Mai, Thu; Linh Pham, Hoai; Le, Van Hong; Do, Hung Manh; Bich Hoa Phan, Thi; Giang Pham, Thi Ha; Nguyen, Dac Tu; Nhung Hoang, Thi My; Lam, Khanh; Quy Nguyen, Thi

    2012-09-01

    In this paper we first summarize our recent research on fabrication and structure characterization of conjugates of Fe3O4 nanoparticles (MNPs) encapsulated by several organic materials such as oleic acid (OL), starch (ST), dextran (D), chitosan (CS), O-carboxymethyl chitosan (OCMCS) and the copolymer of poly(styrene-co-acrylic acid (St-co-AA)). The ferrofluids stability and toxicity were also considered. The magnetic inductive heating (MIH) curves were measured using a set up with an alternating (ac) magnetic field of strength of 40-100 Oe and frequency of 180-240 kHz. We then present new results dealing with attempting to apply the MNP/copolymer ferrofluid for treatment of Sarcoma 180 tumor. In vitro as well as ex vivo MIH experiments were carried out as preparation steps in order to estimate the proper conditions for the in vivo MIH experiment. As for the latter, we have successfully carried out the treatment of solid tumor of size around 6 × 6 mm inoculated on Swiss mice with use of a dose of 0.3-0.4 mg ml-1 ferrofluid injected subcutaneously into the tumor and field-irradiated for 30 min. Two groups of treated mice recovered in three weeks from MIH treatment three times during the first week. We finally show that curcumin loaded MNP-based conjugates showed themselves to be a potential agent for application as a bimodal contrast enhancer of magnetic resonance imaging (MRI) and fluorescence imaging. Additionally, in vitro and ex vivo studies by these two techniques evidenced that macrophage is capable of uptake and tends to carry the MNPs into a tumor.

  10. Iron oxide-based conjugates for cancer theragnostics

    International Nuclear Information System (INIS)

    Nguyen, Xuan Phuc; Tran, Dai Lam; Ha, Phuong Thu; Pham, Hong Nam; Mai, Thu Trang; Pham, Hoai Linh; Le, Van Hong; Do, Hung Manh; Hoa Phan, Thi Bich; Giang Pham, Thi Ha; Nguyen, Dac Tu; Nhung Hoang, Thi My; Nguyen, Thi Quy; Lam, Khanh

    2012-01-01

    In this paper we first summarize our recent research on fabrication and structure characterization of conjugates of Fe 3 O 4 nanoparticles (MNPs) encapsulated by several organic materials such as oleic acid (OL), starch (ST), dextran (D), chitosan (CS), O-carboxymethyl chitosan (OCMCS) and the copolymer of poly(styrene-co-acrylic acid (St-co-AA)). The ferrofluids stability and toxicity were also considered. The magnetic inductive heating (MIH) curves were measured using a set up with an alternating (ac) magnetic field of strength of 40–100 Oe and frequency of 180–240 kHz. We then present new results dealing with attempting to apply the MNP/copolymer ferrofluid for treatment of Sarcoma 180 tumor. In vitro as well as ex vivo MIH experiments were carried out as preparation steps in order to estimate the proper conditions for the in vivo MIH experiment. As for the latter, we have successfully carried out the treatment of solid tumor of size around 6 × 6 mm inoculated on Swiss mice with use of a dose of 0.3–0.4 mg ml −1 ferrofluid injected subcutaneously into the tumor and field-irradiated for 30 min. Two groups of treated mice recovered in three weeks from MIH treatment three times during the first week. We finally show that curcumin loaded MNP-based conjugates showed themselves to be a potential agent for application as a bimodal contrast enhancer of magnetic resonance imaging (MRI) and fluorescence imaging. Additionally, in vitro and ex vivo studies by these two techniques evidenced that macrophage is capable of uptake and tends to carry the MNPs into a tumor. (review)

  11. Structure and magnetic exchange coupling of iron based trilayers

    International Nuclear Information System (INIS)

    Mendus, T.

    1998-12-01

    A study of the structural and magnetic properties of Fe based magnetic trilayers is presented. Sample preparation conditions were altered to achieve the best growth conditions and their effect on the magnetic properties determined. Structural information was obtained from RHEED, AES, STM and MEIS; this is believed to be the first time that MEIS has been used to look at this sort of sample. Magnetic characterisation was determined by MOKE with particular interest paid to the biquadratic coupling. The determination of magnetic coupling as a function of sample morphology was studied oil a series of Fe/Cr/Fe samples. Fe/Au/Fe samples oil MgO substrates were also prepared to facilitate MEIS studies. Results indicate that tile fluctuation model best describes tile observed biquadratic coupling in Fe/Cr/Fe trilayers and that the presence of clean, sharp interfaces is required. Annealing and growth at elevated temperature cause interdiffusion at the interfaces, weakening the biquadratic coupling. MEIS structural data from MgO/Fe/Au/Fe samples shows that tile layer structure is dependent oil thickness. There is an apparent reorganisation of tile Au interlayer between a 'bcc'-Iike phase towards tile bulk fcc phase as the layer thickness increases. MEIS is shown to be a very sensitive probe of the crystalline quality and is a powerful probe for the determination of postdeposition sample morphology. Results from an EC collaboration investigating Co/Cr/Co trilayers are also presented. They showed that interlayer coupling and anisotropy of the samples were very sensitive to the preparation conditions. A decrease in the coupling strength is found for sample growth under non-ideal conditions (growth in an applied field, growth at an angle and delays between layer growth). (author)

  12. Concealed d-wave pairs in the s± condensate of iron-based superconductors.

    Science.gov (United States)

    Ong, Tzen; Coleman, Piers; Schmalian, Jörg

    2016-05-17

    A central question in iron-based superconductivity is the mechanism by which the paired electrons minimize their strong mutual Coulomb repulsion. In most unconventional superconductors, Coulomb repulsion is minimized through the formation of higher angular momentum Cooper pairs, with Fermi surface nodes in the pair wavefunction. The apparent absence of such nodes in the iron-based superconductors has led to a belief they form an s-wave ([Formula: see text]) singlet state, which changes sign between the electron and hole pockets. However, the multiorbital nature of these systems opens an alternative possibility. Here, we propose a new class of [Formula: see text] state containing a condensate of d-wave Cooper pairs, concealed by their entanglement with the iron orbitals. By combining the d-wave ([Formula: see text]) motion of the pairs with the internal angular momenta [Formula: see text] of the iron orbitals to make a singlet ([Formula: see text]), an [Formula: see text] superconductor with a nontrivial topology is formed. This scenario allows us to understand the development of octet nodes in potassium-doped Ba1-x KXFe2As2 as a reconfiguration of the orbital and internal angular momentum into a high spin ([Formula: see text]) state; the reverse transition under pressure into a fully gapped state can then be interpreted as a return to the low-spin singlet. The formation of orbitally entangled pairs is predicted to give rise to a shift in the orbital content at the Fermi surface, which can be tested via laser-based angle-resolved photoemission spectroscopy.

  13. QbD based approach for optimization of Tenofovir disoproxil fumarate loaded liquid crystal precursor with improved permeability

    Directory of Open Access Journals (Sweden)

    Sharvil Patil

    2017-11-01

    Full Text Available BCS class III drugs suffer from a drawback of low permeability even though they have high aqueous solubility. The objective of current work was to screen the suitability of glyceryl monooleate (GMO/Pluronic F127 cubic phase liquid crystals precursors for permeation enhancement and in turn the bioavailability of tenofovir disoproxil fumarate (TDF, a BCS class III drug. Spray-drying method was used for preparation of TDF loaded liquid crystal precursors (LCP consisting of GMO/Pluronic F127 and lactose monohydrate with an ability to in situ transform into stable cubic phases upon hydration. The quality by design (QbD approach (Factorial design was used for batch optimization. Spherical TDF loaded LCP as revealed by scanning electron microscopy photographs when hydrated and analyzed by small angle X-ray scattering confirmed formation of cubic phase. Differential scanning calorimetry and X-ray diffraction studies confirmed the molecular dispersion of TDF in polymer matrix and also suggested the conversion of TDF from crystalline to amorphous form. In vitro TDF release from prepared LCP showed controlled drug release over a period of 10 h. Further ex vivo studies revealed permeation enhancing activity of prepared LCP, which was highest when tested in presence of digestive enzyme extract. Thus, formulation of stable liquid crystal powder precursor can serve as an alternative for designing oral delivery system for drugs with low permeability.

  14. Effect of spin fluctuations on the electronic structure in iron-based superconductors

    Science.gov (United States)

    Heimes, Andreas; Grein, Roland; Eschrig, Matthias

    2012-08-01

    Magnetic inelastic neutron scattering studies of iron-based superconductors reveal a strongly temperature-dependent spin-fluctuation spectrum in the normal conducting state, which develops a prominent low-energy resonance feature when entering the superconducting state. Angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy (STS) allow us to study the fingerprints of fluctuation modes via their interactions with electronic quasiparticles. We calculate such fingerprints in 122 iron pnictides using an experimentally motivated spin-fluctuation spectrum and make a number of predictions that can be tested in ARPES and STS experiments. This includes discussions of the quasiparticle scattering rate and the superconducting order parameter. In quantitative agreement with experiment we reproduce the quasiparticle dispersions obtained from momentum distribution curves as well as energy distribution curves. We discuss the relevance of the coupling between spin fluctuations and electronic excitations for the superconducting mechanism.

  15. Comparison study on transformation of iron oxyhydroxides: Based on theoretical and experimental data

    International Nuclear Information System (INIS)

    Lu Bin; Guo Hui; Li Ping; Liu Hui; Wei Yu; Hou Denglu

    2011-01-01

    We have investigated the catalytic transformation of ferrihydrite, feroxyhyte, and lepidocrocite in the presence of Fe(II). In this paper, the transformation from akaganeite and goethite to hematite in the presence of trace Fe(II) was studied in detail. The result indicates that trace Fe(II) can accelerate the transformation of akaganeite and goethite. Compared with the transformation of other iron oxyhydroxides (e.g., ferrihydrite, feroxyhyte, lepidocrocite, and akaganeite), a complete transformation from goethite to hematite was not observed in the presence of Fe(II). On the basis of our earlier and present experimental results, the transformation of various iron oxyhydroxides was compared based on their thermodynamic stability, crystalline structure, transformation mechanism, and transformation time. - Graphical abstract: The transformation of various iron oxyhydroxides in the presence of trace Fe(II) was compared based on experimental results, thermodynamic stability, crystalline structure, and transformation mechanism. Highlights: → Fe(II) can accelerate the transformation from akaganeite to hematite. → Small particles of goethite can transform to hematite in the presence of Fe(II). → Some hematite particles were found to be embedded within the crystal of goethite. → The relationship between structure and transformation mechanism was revealed.

  16. Solubility and Permeability Studies of Aceclofenac in Different Oils

    African Journals Online (AJOL)

    The solubility and permeability of aceclofenac were compared with the hydroalcoholic solution of ... the use of lipid based systems such as micro- or .... carriers/vehicles for enhanced solubility and permeability ... modifications: A recent review.

  17. Iron from Zealandic bog iron ore -

    DEFF Research Database (Denmark)

    Lyngstrøm, Henriette Syrach

    2011-01-01

    og geologiske materiale, metallurgiske analyser og eksperimentel arkæologiske forsøg - konturerne af en jernproduktion med udgangspunkt i den sjællandske myremalm. The frequent application by archaeologists of Werner Christensen’s distribution map for the occurrence of bog iron ore in Denmark (1966...... are sketched of iron production based on bog iron ore from Zealand....

  18. Micron-Size Zero-Valent Iron Emplacement in Porous Media Using Polymer Additives: Column and Flow Cell Ex-periments

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-03-20

    At the Hanford Site, an extensive In Situ Redox Manipulation (ISRM) permeable reactive barrier was installed to prevent chromate from reaching the Columbia River. However, chromium has been detected in several wells, indicating a premature loss of the reductive capacity in the aquifer. Laboratory experiments have been conducted to investigate whether barrier reductive capacity can be enhanced by adding micron-scale zero-valent iron to the high-permeability zones within the aquifer using shear-thinning fluids containing polymers. Porous media were packed in a wedge-shaped flow cell to create either a heterogeneous layered system with a high-permeability zone between two low-permeability zones or a high-permeability channel sur-rounded by low-permeability materials. The injection flow rate, polymer type, polymer concentration, and injected pore volumes were determined based on preliminary short- and long-column experiments. The flow cell experiments indicated that iron concentration enhancements of at least 0.6% (w/w) could be obtained using moderate flow rates and injection of 30 pore volumes. The 0.6% amended Fe0 concentration would provide approximately 20 times the average reductive capacity that is provided by the dithionite-reduced iron in the ISRM barrier. Calculations show that a 1-m-long Fe0 amended zone with an average concentration of 0.6% w/w iron subject to a groundwater velocity of 1 m/day will have an estimated longevity of 7.2 years.

  19. Fine-Tuned Intrinsically Ultramicroporous Polymers Redefine the Permeability/Selectivity Upper Bounds of Membrane-Based Air and Hydrogen Separations

    KAUST Repository

    Swaidan, Raja

    2015-08-20

    Intrinsically ultramicroporous (<7 Å) polymers represent a new paradigm in materials development for membrane-based gas separation. In particular, they demonstrate that uniting intrachain “rigidity”, the traditional design metric of highly permeable polymers of intrinsic microporosity (PIMs), with gas-sieving ultramicroporosity yields high-performance gas separation membranes. Highly ultramicroporous PIMs have redefined the state-of-the-art in large-scale air (e.g., O2/N2) and hydrogen recovery (e.g., H2/N2, H2/CH4) applications with unprecedented molecular sieving gas transport properties. Accordingly, presented herein are new 2015 permeability/selectivity “upper bounds” for large-scale commercial membrane-based air and hydrogen applications that accommodate the substantial performance enhancements of recent PIMs over preceding polymers. A subtle balance between intrachain rigidity and interchain spacing has been achieved in the amorphous microstructures of PIMs, fine-tuned using unique bridged-bicyclic building blocks (i.e., triptycene, ethanoanthracene and Tröger’s base) in both ladder and semiladder (e.g., polyimide) structures.

  20. Power capability evaluation for lithium iron phosphate batteries based on multi-parameter constraints estimation

    Science.gov (United States)

    Wang, Yujie; Pan, Rui; Liu, Chang; Chen, Zonghai; Ling, Qiang

    2018-01-01

    The battery power capability is intimately correlated with the climbing, braking and accelerating performance of the electric vehicles. Accurate power capability prediction can not only guarantee the safety but also regulate driving behavior and optimize battery energy usage. However, the nonlinearity of the battery model is very complex especially for the lithium iron phosphate batteries. Besides, the hysteresis loop in the open-circuit voltage curve is easy to cause large error in model prediction. In this work, a multi-parameter constraints dynamic estimation method is proposed to predict the battery continuous period power capability. A high-fidelity battery model which considers the battery polarization and hysteresis phenomenon is presented to approximate the high nonlinearity of the lithium iron phosphate battery. Explicit analyses of power capability with multiple constraints are elaborated, specifically the state-of-energy is considered in power capability assessment. Furthermore, to solve the problem of nonlinear system state estimation, and suppress noise interference, the UKF based state observer is employed for power capability prediction. The performance of the proposed methodology is demonstrated by experiments under different dynamic characterization schedules. The charge and discharge power capabilities of the lithium iron phosphate batteries are quantitatively assessed under different time scales and temperatures.

  1. Designing metallic iron based water filters: Light from methylene blue discoloration.

    Science.gov (United States)

    Btatkeu-K, B D; Tchatchueng, J B; Noubactep, C; Caré, S

    2016-01-15

    Available water filtration systems containing metallic iron (Fe(0) filters) are pragmatically designed. There is a lack of sound design criteria to exploit the full potential of Fe(0) filters. A science-based design relies on valuable information on processes within a Fe(0) filter, including chemical reactions, hydrodynamics and their relation to the performance of the filter. The aim of this study was to establish a simple method to evaluate the initial performance of Fe(0) filters. The differential adsorptive affinity of methylene blue (MB) onto sand and iron oxide is exploited to characterize the evolution of a Fe(0)/sand system using the pure sand system as operational reference. Five systems were investigated for more than 70 days: pure sand, pure Fe(0), Fe(0)/sand, Fe(0)/pumice and Fe(0)/sand/pumice. Individual systems were characterized by the extent of changes in pH value, iron breakthrough, MB breakthrough and hydraulic conductivity. Results showed that for MB discoloration (i) pure sand was the most efficient system, (ii) hybrid systems were more sustainable than the pure Fe(0) system, and (iii) the pores of used pumice are poorly interconnected. Characterizing the initial reactivity of Fe(0) filters using MB discoloration has introduced a powerful tool for the exploration of various aspects of filter design. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Magnetic resonance cell-tracking studies: spectrophotometry-based method for the quantification of cellular iron content after loading with superparamagnetic iron oxide nanoparticles.

    Science.gov (United States)

    Böhm, Ingrid

    2011-08-01

    The purpose of this article is to present a user-friendly tool for quantifying the iron content of superparamagnetic labeled cells before cell tracking by magnetic resonance imaging (MRI). Iron quantification was evaluated by using Prussian blue staining and spectrophotometry. White blood cells were labeled with superparamagnetic iron oxide (SPIO) nanoparticles. Labeling was confirmed by light microscopy. Subsequently, the cells were embedded in a phantom and scanned on a 3 T magnetic resonance tomography (MRT) whole-body system. Mean peak wavelengths λ(peak) was determined at A(720 nm) (range 719-722 nm). Linearity was proven for the measuring range 0.5 to 10 μg Fe/mL (r  =  .9958; p  =  2.2 × 10(-12)). The limit of detection was 0.01 μg Fe/mL (0.1785 mM), and the limit of quantification was 0.04 μg Fe/mL (0.714 mM). Accuracy was demonstrated by comparison with atomic absorption spectrometry. Precision and robustness were also proven. On T(2)-weighted images, signal intensity varied according to the iron concentration of SPIO-labeled cells. Absorption spectrophotometry is both a highly sensitive and user-friendly technique that is feasible for quantifying the iron content of magnetically labeled cells. The presented data suggest that spectrophotometry is a promising tool for promoting the implementation of magnetic resonance-based cell tracking in routine clinical applications (from bench to bedside).

  3. Magnetic Resonance Cell-Tracking Studies: Spectrophotometry-Based Method for the Quantification of Cellular Iron Content after Loading with Superparamagnetic Iron Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ingrid Böhm

    2011-07-01

    Full Text Available The purpose of this article is to present a user-friendly tool for quantifying the iron content of superparamagnetic labeled cells before cell tracking by magnetic resonance imaging (MRI. Iron quantification was evaluated by using Prussian blue staining and spectrophotometry. White blood cells were labeled with superparamagnetic iron oxide (SPIO nanoparticles. Labeling was confirmed by light microscopy. Subsequently, the cells were embedded in a phantom and scanned on a 3 T magnetic resonance tomography (MRT whole-body system. Mean peak wavelengths Λpeak was determined at A720nm (range 719–722 nm. Linearity was proven for the measuring range 0.5 to 10 μg Fe/mL (r = .9958; p = 2.2 × 10−12. The limit of detection was 0.01 μg Fe/mL (0.1785 mM, and the limit of quantification was 0.04 μg Fe/mL (0.714 mM. Accuracy was demonstrated by comparison with atomic absorption spectrometry. Precision and robustness were also proven. On T2-weighted images, signal intensity varied according to the iron concentration of SPIO-labeled cells. Absorption spectrophotometry is both a highly sensitive and user-friendly technique that is feasible for quantifying the iron content of magnetically labeled cells. The presented data suggest that spectrophotometry is a promising tool for promoting the implementation of magnetic resonance-based cell tracking in routine clinical applications (from bench to bedside.

  4. Estimation of effective permeability for magnetoactive composites containing multi-chain-structured particles based on the generalized Mori–Tanaka approach

    International Nuclear Information System (INIS)

    Zhang, Haiyu; Wang, Xingzhe

    2014-01-01

    We present an analytic approach to evaluate the effective permeability of multi-chain-structured magnetic particle-filled composites which is formulated by a microstructure-based double-inclusion magnetic model with the generalized Mori–Tanaka theorem. The local magnetic field in a representative volume element (RVE) containing multi-chain-structured particles is derived by using a modified Green’s function. The average fields in the particles, in a matrix coated by particles, and in an effective medium far away from particles are rendered by homogenization of the local magnetic distributions. By means of the relation between the average magnetic field and induction, the effective magnetic permeability of magnetoactive composites is explicitly derived; it exhibits anisotropic and universal behavior. The proposed model has been compared with the available experimental data and other microstructure-based models in the literature; it shows good agreement and gives reliable predictions for magnetic particle-filled composites, especially in terms of capturing the magnetic anisotropic characteristics with respect to the multi-chain-structured particle distribution. (paper)

  5. Itinerant spin dynamics in iron-based superconductors and cerium-based heavy-fermion antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Friemel, Gerd

    2014-05-26

    This thesis contains a comprehensive study of the spin excitations by inelastic neutron scattering (INS) in two different correlated electron systems: the alkali-metal iron selenide superconductors (FeSe122) A{sub x}Fe{sub 2-y}Se{sub 2} (A=K, Rb, Cs) and the heavy-fermion antiferromagnet CeB6. Both systems exhibit intense modes in their spin-fluctuation spectrum below their respective transition temperatures that can be derived from the spin dynamics of the itinerant quasiparticles. However, the implications of these observations, presented here, are different for each particular compound. The A{sub x}Fe{sub 2-y}Se{sub 2} superconductors, with a uniform T{sub c} of 32 K, belong to a qualitative new family of superconductors. They possess a distinctly different Fermi surface compared to the iron-arsenide-based analogues XFe{sub 2}As{sub 2} (X=Ca, Sr, Ba). Instead of the central hole pockets at Γ and the electron pockets at X((1)/(2) 0), which are nested by the Q{sub AFM} = ((1)/(2) 0) vector, there exist only large electron pockets at the X point. Therefore, the magnetic instability along Q{sub AFM} that presumably provides the pairing glue for the superconductivity in the shape of spin fluctuations is absent in the FeSe122. The search for spin fluctuations by INS was motivated by a theoretical analysis that predicted their presence at an incommensurate wave vector near Q = (0.5 δ), δ = 0.3125 which results from a quasinesting by Q between the flat parts of the electron pockets. Two samples, namely Rb{sub 0.8}Fe{sub 1.6}Se{sub 2} and K{sub 0.77}Fe{sub 1.85}Se{sub 2}, were prepared and both showed a sizable anisotropic magnetic response at Q{sub sf} = ((1)/(2) (1)/(4)) in the normal state. Furthermore, upon entering the superconducting (SC) state a strong excitation appears at ℎω{sub res} = 14 meV in the spectrum at Q{sub sf}, which is referred to as magnetic resonant mode. This mode is interpreted as a bound spin-1 exciton below the SC charge gap. Its presence

  6. Itinerant spin dynamics in iron-based superconductors and cerium-based heavy-fermion antiferromagnets

    International Nuclear Information System (INIS)

    Friemel, Gerd

    2014-01-01

    This thesis contains a comprehensive study of the spin excitations by inelastic neutron scattering (INS) in two different correlated electron systems: the alkali-metal iron selenide superconductors (FeSe122) A x Fe 2-y Se 2 (A=K, Rb, Cs) and the heavy-fermion antiferromagnet CeB6. Both systems exhibit intense modes in their spin-fluctuation spectrum below their respective transition temperatures that can be derived from the spin dynamics of the itinerant quasiparticles. However, the implications of these observations, presented here, are different for each particular compound. The A x Fe 2-y Se 2 superconductors, with a uniform T c of 32 K, belong to a qualitative new family of superconductors. They possess a distinctly different Fermi surface compared to the iron-arsenide-based analogues XFe 2 As 2 (X=Ca, Sr, Ba). Instead of the central hole pockets at Γ and the electron pockets at X((1)/(2) 0), which are nested by the Q AFM = ((1)/(2) 0) vector, there exist only large electron pockets at the X point. Therefore, the magnetic instability along Q AFM that presumably provides the pairing glue for the superconductivity in the shape of spin fluctuations is absent in the FeSe122. The search for spin fluctuations by INS was motivated by a theoretical analysis that predicted their presence at an incommensurate wave vector near Q = (0.5 δ), δ = 0.3125 which results from a quasinesting by Q between the flat parts of the electron pockets. Two samples, namely Rb 0.8 Fe 1.6 Se 2 and K 0.77 Fe 1.85 Se 2 , were prepared and both showed a sizable anisotropic magnetic response at Q sf = ((1)/(2) (1)/(4)) in the normal state. Furthermore, upon entering the superconducting (SC) state a strong excitation appears at ℎω res = 14 meV in the spectrum at Q sf , which is referred to as magnetic resonant mode. This mode is interpreted as a bound spin-1 exciton below the SC charge gap. Its presence implies an unconventional order parameter, which changes the sign between the electron

  7. Effect of temperature on sandstone permeability

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Kjøller, Claus

    Hot water injection in geothermal sandstone aquifers is considered for seasonal energy storage in Denmark. However, an increase in the aquifer temperature might reduce permeability, and thereby increase production costs. An understanding of the factors that control permeability is required in order...... and the Klinkenberg procedure showed the expected correlation between the two measures, however, differences could be around one order of magnitude. In tight gas sandstones, permeability is often sensitive to net stress, which might change due to the pore pressure change in the Klinkenberg procedure. Besides...... affecting the Klinkenberg procedure, the combined effect of slip and changes in permeability would affect production during pressure depletion in tight gas sandstone reservoirs; therefore effects of gas slip and net stress on permeability were combined in a model based on the Klinkenberg equation. A lower...

  8. Permeability of porour rhyolite

    Science.gov (United States)

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

    2003-04-01

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

  9. DEVELOPMENT OF ATTRITION RESISTANT IRON-BASED FISCHER-TROPSCH CATALYSTS

    International Nuclear Information System (INIS)

    Adeyinka A. Adeyiga

    2001-01-01

    The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H 2 ) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. The use of iron-based catalysts is attractive not only due to their low cost and ready availability, but also due to their high water-gas shift activity which makes it possible to use these catalysts with low H 2 /CO ratios. However, a serious problem with use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, makes the separation of catalyst from the oil/wax product very difficult if not impossible, and results in a steady loss of catalyst from the reactor. Recently, fundamental understanding of physical attrition is being addressed by incorporating suitable binders into the catalyst recipe. This has resulted in the preparation of a spray dried Fe-based catalyst having aps of 70 mm with high attrition resistance. This Fe-based attrition resistant, active and selective catalyst gave 95% CO conversion through 125 hours of testing in a fixed-bed at 270 C, 1.48 MPa, H 2 /CO=0.67 and 2.0 NL/g-cat/h with C 5 + selectivity of >78% and methane selectivity of <5%. However, further development of the catalyst is needed to address the chemical attrition due to phase changes that any Fe-catalyst goes through potentially causing internal stresses within the particle and resulting in weakening, spalling or cracking. The objective of this research is to develop robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry bubble column reactor. Specifically we aim to develop to: (i) improve the performance and preparation procedure of the high activity, high attrition resistant, high alpha iron-based

  10. Controlling DC permeability in cast steels

    International Nuclear Information System (INIS)

    Sumner, Aaran; Gerada, Chris; Brown, Neil; Clare, Adam

    2017-01-01

    Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

  11. Controlling DC permeability in cast steels

    Energy Technology Data Exchange (ETDEWEB)

    Sumner, Aaran, E-mail: aaran.sumner@nottingham.ac.uk [University of Nottingham, Nottingham University Park Campus, Nottingham NG7 2RD, England (United Kingdom); Gerada, Chris, E-mail: chris.gerada@nottingham.ac.uk [Electrical Machines, University of Nottingham, Tower Building, Nottingham NG7 2RD, England (United Kingdom); Brown, Neil, E-mail: neil.brown@cummins.com [Advanced Electrical Machines Research and Technology at Cummins Power Generation, Peterborough PE2 6FZ, England (United Kingdom); Clare, Adam, E-mail: adam.clare@nottingham.ac.uk [Advanced Manufacturing, University of Nottingham, University Park Campus, Nottingham NG7 2RD, England (United Kingdom)

    2017-05-01

    Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

  12. Charge Ordering, Competing Magnetic Interactions, and Magneto-Resistance Effects in Layered Iron(IV)-Based Oxides

    International Nuclear Information System (INIS)

    Adler, P.; Ghosh, S.

    2002-01-01

    Iron(IV)-based Ruddlesden-Popper-type oxides Sr 3 Fe 2-x Co x O 7-y (0≤x≤1) have been synthesized and studied by various techniques. It is shown that iron-57 Moessbauer spectroscopy is a powerful tool for elucidating the intimate correlations between chemical composition, electron-transport properties, electronic state, magnetism, and the large magneto-resistance effects in this system.

  13. Is outdoor work associated with elevated rates of cerebrovascular disease mortality? : a cohort study based on iron-ore mining

    OpenAIRE

    Björ, Ove; Jonsson, Håkan; Damber, Lena; Burström, Lage; Nilsson, Tohr

    2016-01-01

    BACKGROUND: A cohort study that examined iron ore mining found negative associations between cumulative working time employed underground and several outcomes, including mortality of cerebrovascular diseases. In this cohort study, and using the same group of miners, we examined whether work in an outdoor environment could explain elevated cerebrovascular disease rates. METHODS: This study was based on a Swedish iron ore mining cohort consisting of 13,000 workers. Poisson regression models wer...

  14. 基于压水试验的深部煤层底板岩层阻渗性能研究∗%Study on permeability barrier performance of deep coal seam floor based on packer permeability test

    Institute of Scientific and Technical Information of China (English)

    孙晓倩; 张冬; 张新武; 王言剑

    2014-01-01

    In situ field packer permeability test,being a reliable method to obtain the param-eters of permeability barrier performance of strata,was used to explore this performance of deep coal seam floor. A large amount of measured data were obtained after the test on two layers of floor strata. The test results showed that these two layers of floor strata could not seep in initial state due to stronger barrier performance until the fracture and connection led to seepage. Co MPared with the first and repeated packer permeability tests on these two layers of floor strata, the variation of water pressure in measured pore was associated with that in water injection hole, but the seepage pressure in the first time was higher than that in second time,showing that the permeability barrier performance of strata turned weaker after first packer permeability test and was easy to form seepage. Using permeability coefficient and permeability barrier strength as in-dexes,the permeability barrier performance of floor strata has been quantitatively evaluated,and the results showed that the tested strata was characterized with high barrier performance and weak permeability.%原位现场压水试验是获取岩层阻渗性能参数的可靠方法,为探究某煤矿深部煤层底板阻渗能力,采用现场压水试验方法对底板两段岩层进行了测试并获取了大量的实测数据。结果分析表明:该底板两测试段岩层在原始状态均不导渗,阻渗性较强,直至压裂导通才形成导渗条件;对两段岩层均进行了初次和重复两个压水过程,对比两次试验可知,测渗孔水压力与注水孔水压力的关联变化趋势大致相同,但初次压水的起始导渗水压明显高于重复压水,表明在初次压水后岩层的阻渗能力降低,更易形成导渗;采用渗透系数和阻渗强度作为指标,对底板岩层的阻渗性能进行了量化评价,结果表明测试岩层表现出明显的高阻弱渗的特点。

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... conditions that can cause iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen ... the size of your liver and spleen. Blood tests Based on results from blood tests to screen ...

  16. Development and validation of a HPLC method for the assay of dapivirine in cell-based and tissue permeability experiments.

    Science.gov (United States)

    das Neves, José; Sarmento, Bruno; Amiji, Mansoor; Bahia, Maria Fernanda

    2012-12-12

    Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is being currently used for the development of potential anti-HIV microbicide formulations and delivery systems. A new high-performance liquid chromatography (HPLC) method with UV detection was developed for the assay of this drug in different biological matrices, namely cell lysates, receptor media from permeability experiments and homogenates of mucosal tissues. The method used a reversed-phase C18 column with a mobile phase composed of trifluoroacetic acid solution (0.1%, v/v) and acetonitrile in a gradient mode. Injection volume was 50μL and the flow rate 1mL/min. The total run time was 12min and UV detection was performed at 290nm for dapivirine and the internal standard (IS) diphenylamine. A Box-Behnken experimental design was used to study different experimental variables of the method, namely the ratio of the mobile phase components and the gradient time, and their influence in responses such as the retention factor, tailing factor, and theoretical plates for dapivirine and the IS, as well as the peak resolution between both compounds. The optimized method was further validated and its usefulness assessed for in vitro and ex vivo experiments using dapivirine or dapivirine-loaded nanoparticles. The method showed to be selective, linear, accurate and precise in the range of 0.02-1.5μg/mL. Other chromatographic parameters, namely carry-over, lower limit of quantification (0.02μg/mL), limit of detection (0.006μg/mL), recovery (equal or higher than 90.7%), and sample stability at different storage conditions, were also determined and found adequate for the intended purposes. The method was successfully used for cell uptake assays and permeability studies across cell monolayers and pig genital mucosal tissues. Overall, the proposed method provides a simple, versatile and reliable way for studying the behavior of dapivirine in different biological matrices and assessing its potential as an anti

  17. Evaluation of iron-base materials for waste package containers in a salt repository

    International Nuclear Information System (INIS)

    Westerman, R.E.; Nelson, J.L.; Kuhn, W.L.; Basham, S.G.; Moak, D.A.; Pitman, S.G.

    1983-11-01

    Design studies for high-level nuclear waste packages for salt repositories have identified low-carbon steel as a candidate material for containers. Among the requirements are strength, corrosion resistance, and fabricability. The studies of the corrosion resistance and structural stability of iron-base materials (particularly low-carbon steel) are treated in this paper. The materials have been exposed in brines that are characteristic of the potential sites for salt repositories. The effects of temperature, radiation level, oxygen level and other parameters are under investigation. The initial development of corrosion models for these environments is presented with discussion of the key mechanisms under consideration. 6 references, 5 figures

  18. Gigantic uniaxial pressure effect in single crystals of iron-based superconductors

    International Nuclear Information System (INIS)

    Nakashima, Y.; Yui, H.; Sasagawa, T.

    2010-01-01

    In order to elucidate the anisotropic pressure effect on superconductivity in an iron-based superconductor, magnetization measurements have been performed in Ba(Fe 0.92 Co 0.08 ) 2 As 2 single crystals under uniaxial pressures applied along the c-axis. Gigantic T c suppression, dT c /dP //c = -15 K/GPa, was observed when the anisotropic deformation with the a-expansion and c-compression was induced by the c-pressure, which should be compared with dT c /dP c .

  19. Interstitial-phase precipitation in iron-base alloys: a comparative study

    International Nuclear Information System (INIS)

    Pelton, A.R.

    1982-06-01

    Recent developments have elucidated the atomistic mechanisms of precipitation of interstitial elements in simple alloy systems. However, in the more technologically important iron base alloys, interstitial phase precipitation is generally not well understood. The present experimental study was therefore designed to test the applicability of these concepts to more complex ferrous alloys. Hence, a comparative study was made of interstitial phase precipitation in ferritic Fe-Si-C and in austenitic phosphorus-containing Fe-Cr-Ni steels. These systems were subjected to a variety of quench-age thermal treatments, and the microstructural development was subsequently characterized by transmission electron microscopy

  20. Soils - Mean Permeability

    Data.gov (United States)

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

  1. Hydrogen permeability through metals

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  2. In-gap bound states induced by interstitial Fe impurities in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Degang, E-mail: degangzhang@yahoo.com

    2015-12-15

    Highlights: • We provide an explanation for the interesting STM observation of the robust zero energy bound state on the interstitial Fe impurities in iron-based superconductors. - Abstract: Based on a two-orbit four-band tight binding model, we investigate the low-lying electronic states around the interstitial excess Fe ions in the iron-based superconductors by using T-matrix approach. It is shown that the local density of states at the interstitial Fe impurity (IFI) possesses a strong resonance inside the gap, which seems to be insensitive to the doping and the pairing symmetry in the Fe–Fe plane, while a single or two resonances appear at the nearest neighboring (NN) Fe sites. The location and height of the resonance peaks only depend on the hopping t and the pairing parameter Δ{sub I} between the IFI and the NN Fe sites. These in-gap resonances are originated in the Andreev’s bound states due to the quasiparticle tunneling through the IFI, leading to the change of the magnitude of the superconducting order parameter. When both t and Δ{sub I} are small, this robust zero-energy bound state near the IFI is consistent with recent scanning tunneling microscopy observations.

  3. Softening of the elastic shear mode C{sub 66} in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Boehmer, Anna; Burger, Philipp [Karlsruher Institut fuer Technologie, Institut fuer Festkoerperphysik, D-76021 Karlsruhe (Germany); Karlsruher Institut fuer Technologie, Fakultaet fuer Physik, D-76128 Karlsruhe (Germany); Hardy, Frederic; Schweiss, Peter; Fromknecht, Rainer; Wolf, Thomas; Meingast, Christoph [Karlsruher Institut fuer Technologie, Institut fuer Festkoerperphysik, D-76021 Karlsruhe (Germany); Reinecker, Marius; Schranz, Wilfried [Universitaet Wien, Fakultaet fuer Physik, A-1090 Wien, Vienna (Austria)

    2013-07-01

    The structural phase transition of underdoped iron-based superconductors is accompanied by a large softening of the elastic shear mode C{sub 66}, which has attracted considerable attention. This softening has been discussed both in terms of orbital and spin-nematic fluctuations which would be responsible for the structural phase transition and, possibly, superconductivity. However, sample requirements have so far restricted experimental investigations of C{sub 66} (via measurements of the ultrasound velocity) to the Ba(Fe,Co){sub 2}As{sub 2} system. Here, we report on a new technique, based on a three-point bending setup, to probe the Young's modulus of a sample with a capacitance dilatometer. For certain orientations, the Young's modulus is related to the elastic constant C{sub 66} whose effective temperature dependence can be obtained. Platelet-like samples, as frequently encountered for iron-based systems, are easily studied with our setup. Data on several systems are presented and discussed.

  4. Model-Assisted Control of Flow Front in Resin Transfer Molding Based on Real-Time Estimation of Permeability/Porosity Ratio

    Directory of Open Access Journals (Sweden)

    Bai-Jian Wei

    2016-09-01

    Full Text Available Resin transfer molding (RTM is a popular manufacturing technique that produces fiber reinforced polymer (FRP composites. In this paper, a model-assisted flow front control system is developed based on real-time estimation of permeability/porosity ratio using the information acquired by a visualization system. In the proposed control system, a radial basis function (RBF network meta-model is utilized to predict the position of the future flow front by inputting the injection pressure, the current position of flow front, and the estimated ratio. By conducting optimization based on the meta-model, the value of injection pressure to be implemented at each step is obtained. Moreover, a cascade control structure is established to further improve the control performance. Experiments show that the developed system successfully enhances the performance of flow front control in RTM. Especially, the cascade structure makes the control system robust to model mismatch.

  5. Nanoscale structure and atomic disorder in the iron-based chalcogenides

    Directory of Open Access Journals (Sweden)

    Naurang Lal Saini

    2013-01-01

    Full Text Available The multiband iron-based superconductors have layered structure with a phase diagram characterized by a complex interplay of charge, spin and lattice excitations, with nanoscale atomic structure playing a key role in their fundamental electronic properties. In this paper, we briefly review nanoscale structure and atomic disorder in iron-based chalcogenide superconductors. We focus on the Fe(Se,S1−xTex (11-type and K0.8Fe1.6Se2 (122-type systems, discussing their local structure obtained by extended x-ray absorption fine structure. Local structure studies on the Fe(Se,S1−xTex system reveal clear nanoscale phase separation characterized by coexisting components of different atomic configurations, similar to the case of random alloys. In fact, the Fe–Se/S and Fe–Te distances in the ternary Fe(Se,S1−xTex are found to be closer to the respective distances in the binary FeSe/FeS and FeTe systems, showing significant divergence of the local structure from the average one. The observed features are characteristic of ternary random alloys, indicating breaking of the local symmetry in these materials. On the other hand, K0.8Fe1.6Se2 is known for phase separation in an iron-vacancy ordered phase and an in-plane compressed lattice phase. The local structure of these 122-type chalcogenides shows that this system is characterized by a large local disorder. Indeed, the experiments suggest a nanoscale glassy phase in K0.8Fe1.6Se2, with the superconductivity being similar to the granular materials. While the 11-type structure has no spacer layer, the 122-type structure contains intercalated atoms unlike the 1111-type REFeAsO (RE = rare earth oxypnictides, having well-defined REO spacer layers. It is clear that the interlayer atomic correlations in these iron-based superconducting structures play an important role in structural stability as well as superconductivity and magnetism.

  6. Compact rock material gas permeability properties

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-15

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

  7. Permeability During Magma Expansion and Compaction

    Science.gov (United States)

    Gonnermann, Helge. M.; Giachetti, Thomas; Fliedner, Céline; Nguyen, Chinh T.; Houghton, Bruce F.; Crozier, Joshua A.; Carey, Rebecca J.

    2017-12-01

    Plinian lapilli from the 1060 Common Era Glass Mountain rhyolitic eruption of Medicine Lake Volcano, California, were collected and analyzed for vesicularity and permeability. A subset of the samples were deformed at a temperature of 975°, under shear and normal stress, and postdeformation porosities and permeabilities were measured. Almost all undeformed samples fall within a narrow range of vesicularity (0.7-0.9), encompassing permeabilities between approximately 10-15 m2 and 10-10 m2. A percolation threshold of approximately 0.7 is required to fit the data by a power law, whereas a percolation threshold of approximately 0.5 is estimated by fitting connected and total vesicularity using percolation modeling. The Glass Mountain samples completely overlap with a range of explosively erupted silicic samples, and it remains unclear whether the erupting magmas became permeable at porosities of approximately 0.7 or at lower values. Sample deformation resulted in compaction and vesicle connectivity either increased or decreased. At small strains permeability of some samples increased, but at higher strains permeability decreased. Samples remain permeable down to vesicularities of less than 0.2, consistent with a potential hysteresis in permeability-porosity between expansion (vesiculation) and compaction (outgassing). We attribute this to retention of vesicle interconnectivity, albeit at reduced vesicle size, as well as bubble coalescence during shear deformation. We provide an equation that approximates the change in permeability during compaction. Based on a comparison with data from effusively erupted silicic samples, we propose that this equation can be used to model the change in permeability during compaction of effusively erupting magmas.

  8. Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

    KAUST Repository

    Pan, Yue; Gao, Jinhao; Zhang, Bei; Zhang, Xixiang; Xu, Bing

    2010-01-01

    nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X

  9. Intestinal Permeability: The Basics

    Directory of Open Access Journals (Sweden)

    Ingvar Bjarnason

    1995-01-01

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

  10. Permeable treatment wall design and cost analysis

    International Nuclear Information System (INIS)

    Manz, C.; Quinn, K.

    1997-01-01

    A permeable treatment wall utilizing the funnel and gate technology has been chosen as the final remedial solution for one industrial site, and is being considered at other contaminated sites, such as a closed municipal landfill. Reactive iron gates will be utilized for treatment of chlorinated VOCs identified in the groundwater. Alternatives for the final remedial solution at each site were evaluated to achieve site closure in the most cost effective manner. This paper presents the remedial alternatives and cost analyses for each site. Several options are available at most sites for the design of a permeable treatment wall. Our analysis demonstrates that the major cost factor's for this technology are the design concept, length, thickness, location and construction methods for the reactive wall. Minimizing the amount of iron by placement in the most effective area and construction by the lowest cost method is critical to achieving a low cost alternative. These costs dictate the design of a permeable treatment wall, including selection of a variety of alternatives (e.g., a continuous wall versus a funnel and gate system, fully penetrating gates versus partially penetrating gates, etc.). Selection of the appropriate construction methods and materials for the site can reduce the overall cost of the wall

  11. Siderophore-based microbial adaptations to iron scarcity across the eastern Pacific Ocean

    Science.gov (United States)

    Boiteau, Rene M.; Mende, Daniel R.; Hawco, Nicholas J.; McIlvin, Matthew R.; Fitzsimmons, Jessica N.; Saito, Mak A.; Sedwick, Peter N.; DeLong, Edward F.; Repeta, Daniel J.

    2016-12-01

    Nearly all iron dissolved in the ocean is complexed by strong organic ligands of unknown composition. The effect of ligand composition on microbial iron acquisition is poorly understood, but amendment experiments using model ligands show they can facilitate or impede iron uptake depending on their identity. Here we show that siderophores, organic compounds synthesized by microbes to facilitate iron uptake, are a dynamic component of the marine ligand pool in the eastern tropical Pacific Ocean. Siderophore concentrations in iron-deficient waters averaged 9 pM, up to fivefold higher than in iron-rich coastal and nutrient-depleted oligotrophic waters, and were dominated by amphibactins, amphiphilic siderophores with cell membrane affinity. Phylogenetic analysis of amphibactin biosynthetic genes suggests that the ability to produce amphibactins has transferred horizontally across multiple Gammaproteobacteria, potentially driven by pressures to compete for iron. In coastal and oligotrophic regions of the eastern Pacific Ocean, amphibactins were replaced with lower concentrations (1-2 pM) of hydrophilic ferrioxamine siderophores. Our results suggest that organic ligand composition changes across the surface ocean in response to environmental pressures. Hydrophilic siderophores are predominantly found across regions of the ocean where iron is not expected to be the limiting nutrient for the microbial community at large. However, in regions with intense competition for iron, some microbes optimize iron acquisition by producing siderophores that minimize diffusive losses to the environment. These siderophores affect iron bioavailability and thus may be an important component of the marine iron cycle.

  12. Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors.

    Science.gov (United States)

    Li, Jun; Ji, Min; Schwarz, Tobias; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Yuan, Jie; Pereira, Paulo J; Huang, Ya; Zhang, Gufei; Feng, Hai-Luke; Yuan, Ya-Hua; Hatano, Takeshi; Kleiner, Reinhold; Koelle, Dieter; Chibotaru, Liviu F; Yamaura, Kazunari; Wang, Hua-Bing; Wu, Pei-Heng; Takayama-Muromachi, Eiji; Vanacken, Johan; Moshchalkov, Victor V

    2015-07-03

    The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm(2) cross-section. The impurities suppress superconductivity in a three-dimensional 'Swiss cheese'-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.

  13. Competing orders in strongly correlated systems. Dirac materials and iron-based superconductors

    International Nuclear Information System (INIS)

    Classen, Laura

    2016-01-01

    In this work we address the collective phenomena appearing in interacting fermion systems due to the competition of distinct orders at the example of Dirac materials and iron-based superconductors. On the one hand we determine leading ordering tendencies in an unbiased way, when Fermi liquid instabilities are expected simultaneously in the particle-particle and particle-hole channel. In this context we analyze the impact of electron-phonon interactions on the many-body instabilities of electrons on the honeycomb lattice. Furthermore we investigate the interplay between superconductivity, magnetism and orbital order in five-pocket iron-based superconductors including the full orbital composition of low-energy excitations. On the other hand we study how the close proximity of different phases affects the structure of the phase diagram and the nature of transitions, as well as the corresponding quantum multicritical behavior. To this end we consider the semimetal-insulator transitions to an antiferromagnetic and a staggered-density state of low-energy Dirac fermions. To account for the decisive role of interactions and the various degrees of freedom in these models, modern renormalization group techniques are applied.

  14. Anisotropy of the Seebeck and Nernst coefficients in parent compounds of the iron-based superconductors

    Science.gov (United States)

    Matusiak, Marcin; Babij, Michał; Wolf, Thomas

    2018-03-01

    In-plane longitudinal and transverse thermoelectric phenomena in two parent compounds of iron-based superconductors are studied. Namely, the Seebeck (S ) and Nernst (ν) coefficients were measured in the temperature range 10-300 K for BaF e2A s2 and CaF e2A s2 single crystals that were detwinned in situ. The thermoelectric response shows sizable anisotropy in the spin density wave (SDW) state for both compounds, while some dissimilarities in the vicinity of the SDW transition can be attributed to the different nature of the phase change in BaF e2A s2 and CaF e2A s2 . Temperature dependences of S and ν can be described within a two-band model that contains a contribution from highly mobile, probably Dirac, electrons. The Dirac band seems to be rather isotropic, whereas most of the anisotropy in the transport phenomena could be attributed to "regular" holelike charge carriers. We also observe that the off-diagonal element of the Peltier tensor αx y is not the same for the a and b orthorhombic axes, which indicates that the widely used Mott formula is not applicable to the SDW state of iron-based superconductors.

  15. Cyclic Oxidation and Hot Corrosion Behavior of Nickel-Iron-Based Superalloy

    Science.gov (United States)

    Chellaganesh, D.; Adam Khan, M.; Winowlin Jappes, J. T.; Sathiyanarayanan, S.

    2018-01-01

    The high temperature oxidation and hot corrosion behavior of nickel-iron-based superalloy are studied at 900 ° and 1000 °C. The significant role of alloying elements with respect to the exposed medium is studied in detail. The mass change per unit area was catastrophic for the samples exposed at 1000 °C and gradual increase in mass change was observed at 900 °C for both the environments. The exposed samples were further investigated with SEM, EDS and XRD analysis to study the metallurgical characteristics. The surface morphology has expressed the in situ nature of the alloy and its affinity toward the environment. The EDS and XRD analysis has evidently proved the presence of protective oxides formation on prolonged exposure at elevated temperature. The predominant oxide formed during the exposure at high temperature has a major contribution toward the protection of the samples. The nickel-iron-based superalloy is less prone to oxidation and hot corrosion when compared to the existing alloy in gas turbine engine simulating marine environment.

  16. Competing orders in strongly correlated systems. Dirac materials and iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Classen, Laura

    2016-11-04

    In this work we address the collective phenomena appearing in interacting fermion systems due to the competition of distinct orders at the example of Dirac materials and iron-based superconductors. On the one hand we determine leading ordering tendencies in an unbiased way, when Fermi liquid instabilities are expected simultaneously in the particle-particle and particle-hole channel. In this context we analyze the impact of electron-phonon interactions on the many-body instabilities of electrons on the honeycomb lattice. Furthermore we investigate the interplay between superconductivity, magnetism and orbital order in five-pocket iron-based superconductors including the full orbital composition of low-energy excitations. On the other hand we study how the close proximity of different phases affects the structure of the phase diagram and the nature of transitions, as well as the corresponding quantum multicritical behavior. To this end we consider the semimetal-insulator transitions to an antiferromagnetic and a staggered-density state of low-energy Dirac fermions. To account for the decisive role of interactions and the various degrees of freedom in these models, modern renormalization group techniques are applied.

  17. The 3-Dimensional Fermi Liquid Description for the Iron-Based Superconductors

    Science.gov (United States)

    Misawa, Setsuo

    2018-01-01

    The quasiparticles in the normal state of iron-based superconductors have been shown to behave universally as a 3-dimensional Fermi liquid. Because of interactions and the presence of sharp Fermi surfaces, the quasiparticle energy contains, as a function of the momentum \\varvec{p}, a term of the form ( p - p_0)^3 ln {( |p-p_0|/p_0)} , where p = | \\varvec{p} | and p_0 is the Fermi momentum. The electronic specific heat coefficient, magnetic susceptibility (Knight shift), electrical resistivity, Hall coefficient and thermoelectric power divided by temperature follow, as functions of temperature T, the logarithmic formula a-b T^2 ln {(T/T^*)}, a, b and T^* being constant; these formulae have been shown to explain the observed data for all iron-based superconductors. It is shown that the concept of non-Fermi liquids or anomalous metals which appears in the literature is not needed for descriptions of the present systems. When the superconducting transition temperature TC and the b / a value for the resistivity are plotted as functions of the doping content x, there appear various characteristic diagrams in which regions of positive correlation and those of negative correlation between TC and b / a are interconnected; from these diagrams, we may make speculations about the types of superconductivity and the crossover between them.

  18. Development of in-situ ZrC reinforced iron based composites for wear resistance applications

    International Nuclear Information System (INIS)

    Bandyopadhyay, T.K.; Das, K.

    2002-01-01

    A common objective behind the processing of iron-based composites is to improve the wear resistance of steels by incorporating some reinforcing phases, e.g., carbides and oxides. In the present investigation, iron-based zirconium carbide reinforced composite is produced by the aluminothermic reduction of zircon sand (ZrSiO 4 ) and blue dust (Fe 2 O 3 ) in the presence of carbon. Aluminothermic reduction of blue dust and zircon sand, being highly exothermic in nature, essentially leads to a self-propagating high-temperature synthesis (SHS) of the Fe-ZrC composite. The as-cast composite is characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical properties of the composite and the effect of heat treatment on the microstructure are evaluated. The composite possess sufficient hardness and promising abrasive wear resistance property. The abrasive wear resistance property of the Fe-ZrC composite is compared with that of a M2 grade tool material and it is found to be better than the tool material. The composite also possess good high temperature stability. (author)

  19. Embrittlement of nickel-, cobalt-, and iron-base superalloys by exposure to hydrogen

    Science.gov (United States)

    Gray, H. R.

    1975-01-01

    Five nickel-base alloys (Inconel 718, Udimet 700, Rene 41, Hastelloy X, and TD-NiCr), one cobalt-base alloy (L-605), and an iron-base alloy (A-286) were exposed in hydrogen at 0.1 MN/sq m (15 psi) at several temperatures in the range from 430 to 980 C for as long as 1000 hours. These alloys were embrittled to varying degrees by such exposures in hydrogen. Embrittlement was found to be: (1) sensitive to strain rate, (2) reversible, (3) caused by large concentrations of absorbed hydrogen, and (4) not associated with any detectable microstructural changes in the alloys. These observations are consistent with a mechanism of internal reversible hydrogen embrittlement.

  20. In Vitro Iron Bioavailability of Brazilian Food-Based by-Products.

    Science.gov (United States)

    Chiocchetti, Gabriela M; De Nadai Fernandes, Elisabete A; Wawer, Anna A; Fairweather-Tait, Susan; Christides, Tatiana

    2018-05-16

    Background : Iron deficiency is a public health problem in many low- and middle-income countries. Introduction of agro-industrial food by-products, as additional source of nutrients, could help alleviate this micronutrient deficiency, provide alternative sources of nutrients and calories in developed countries, and be a partial solution for disposal of agro-industry by-products. Methods : The aim of this study was to determine iron bioavailability of 5 by-products from Brazilian agro-industry (peels from cucumber, pumpkin, and jackfruit, cupuaçu seed peel, and rice bran), using the in vitro digestion/ Caco-2 cell model; with Caco-2 cell ferritin formation as a surrogate marker of iron bioavailability. Total and dialyzable Fe, macronutrients, the concentrations of iron-uptake inhibitors (phytic acid, tannins, fiber) and their correlation with iron bioavailability were also evaluated. Results : The iron content of all by-products was high, but the concentration of iron and predicted bioavailability were not related. Rice bran and cupuaçu seed peel had the highest amount of phytic acid and tannins, and lowest iron bioavailability. Cucumber peels alone, and with added extrinsic Fe, and pumpkin peels with extrinsic added iron, had the highest iron bioavailability. Conclusion : The results suggest that cucumber and pumpkin peel could be valuable alternative sources of bioavailable Fe to reduce iron deficiency in at-risk populations.

  1. Hydrogen transport in iron and steel

    International Nuclear Information System (INIS)

    Louthan, M.R. Jr.; Derrick, R.G.; Donovan, J.A.; Caskey, G.R. Jr.

    1975-01-01

    The permeabilities of protium, deuterium, and tritium in iron and T-1 steel at temperatures as low as 260 0 K are in agreement with the equation proposed by Gonzalez. However, the permeabilities of HP-9-4-20 and 4130 steel to hydrogen are typically lower than predicted. The present data also show that, within experimental accuracy, the isotope effect on the permeability of hydrogen in HP-9-4-20, 4130 and T-1 steel, and high purity iron can be estimated by an inverse square root of mass correction. Trapping effects prevent the development of diffusivity and solubility equations. (auth)

  2. Nature based solutions to mitigate soil sealing in urban areas: Results from a 4-year study comparing permeable, porous, and impermeable pavements.

    Science.gov (United States)

    Fini, A; Frangi, P; Mori, J; Donzelli, D; Ferrini, F

    2017-07-01

    Soil sealing is one of the most pervasive forms of soil degradation that follows urbanization and, despite innovative pavements (i.e. pervious) are being installed in urban areas to mitigate it, there is little research on the effects of pervious pavements on soil water and carbon cycle and on the physiology of urban trees. The aim of this 4-year experiment was to assess the effects of three pavements, differing in permeability to water and gases, on some soil physical parameters, and on growth and physiology of newly planted Celtis australis and Fraxinus ornus. Treatments were: 1) impermeable pavement (asphalt on concrete sub-base); 2) permeable pavement (pavers on crushed rock sub-base); 3) porous design (porous pavement on crushed rock sub-base); 4) control (unpaved soil, kept free of weed by chemical control). Soil (temperature, moisture, oxygen content and CO 2 efflux) and plant (above- and below-ground growth, leaf gas exchange, chlorophyll fluorescence, water relations) parameters were measured. All types of pavements altered the water cycle compared to unpaved soil plots, but this disturbance was less intense in porous pavements than in other soil cover types. Porous pavements allowed both higher infiltration and evaporation of water than both pavers and asphalt. Reduction of evaporative cooling from soil paved with permeable and impermeable pavements contributed to significant soil warming: at 20cm depth, soils under concrete pavers and asphalt were 4 and 5°C warmer than soil covered by porous pavements and unpaved soils, respectively. Thus, enhancing evaporation from paved soil by the use of porous pavements may contribute to mitigating urban heat islands. CO 2 greatly accumulated under impermeable and permeable pavements, but not under porous pavements, which showed CO 2 efflux rates similar to control. Soil oxygen slightly decreased only beneath asphalt. Growth of newly planted C. australis and F. ornus was little affected by pavement type. Tree

  3. Iron based superconductors and related compounds synthesized by solid state metathesis and high temperature reactions

    International Nuclear Information System (INIS)

    Frankovsky, Rainer

    2013-01-01

    The results of this thesis can be divided into three major topics, which can also be seen as different approaches of solid state chemistry to reveal interesting features of known and unknown compounds and to develop alternative synthesis routes. Firstly, known compounds with related structural motifs to the superconducting iron-arsenides were investigated regarding their structural and physical properties. In case of La 3 Pd 4 Ge 4 the influence of Fe doping on the properties was studied, whereas in the series ZrMAs (M=Ti,V) the physical properties have not yet been reported at all and were investigated for the first time. Secondly, an alternative synthesis route has been developed for the synthesis of superconducting LaFeAsO 1-x F x . This solid state metathesis reaction distinctly increased the quality of the samples compared to conventionally prepared products. Furthermore, the reaction pathway was investigated and clarified, which helps to understand the processes during high temperature solid state metathesis reactions in general. Thirdly, this alternative synthesis route was expanded to other systems and new compounds like co-substituted LaFe 1-x Mn x AsO 1-y F y were prepared and thoroughly investigated. This led to a complex study of the interplay of magnetism, electronic and structural conditions and the occurrence of superconducting properties. The investigation and understanding of such complex coherences will probably be decisive for the further understanding of the superconducting mechanism in iron based superconductors.

  4. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    Energy Technology Data Exchange (ETDEWEB)

    Zacchia, Nicholas A.; Valentine, Megan T. [Department of Mechanical Engineering and Materials Research Laboratory, University of California, Santa Barbara, California 93106 (United States)

    2015-05-15

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  5. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications.

    Science.gov (United States)

    Zacchia, Nicholas A; Valentine, Megan T

    2015-05-01

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  6. An Evaluation of Neutron Energy Spectrum Effects in Iron Based on Molecular Dynamics Displacement Cascade Simulations

    International Nuclear Information System (INIS)

    Greenwood, L.R.; Stoller, R.E.

    1998-01-01

    The results of molecular dynamics (MD) displacement cascade simulations in bcc iron have been used to obtain effective cross sections for two measures of primary damage production: (1) the number of surviving point defects expressed as a fraction of the displacements calculated using the standard secondary displacement model of Norgett, Robinson, and Torrens (NRT), and (2) the fraction of the surviving interstitials contained in clusters that formed during the cascade event. Primary knockon atom spectra for iron obtained from the SPECTER code have been used to weight these MD-based damage production cross sections in order to obtain spectrally-averaged values for several locations in commercial fission reactors and materials test reactors. An evaluation of these results indicates that neutron energy spectrum differences between the various enviromnents do not lead to significant differences between the average primary damage formation parameters. In particular, the defect production cross sections obtained for PWR and BWR neutron spectra were not significantly different. The variation of the defect production cross sections as a function of depth into the reactor pressure vessel wall is used as a sample application of the cross sections. A slight difference between the attenuation behavior of the PWR and BWR was noted; this difference could be explained by a subtle difference in the energy dependence of the neutron spectra. Overall, the simulations support the continued use of dpa as a damage correlation parameter

  7. Neutron Spin Resonance in the 112-Type Iron-Based Superconductor

    Science.gov (United States)

    Xie, Tao; Gong, Dongliang; Ghosh, Haranath; Ghosh, Abyay; Soda, Minoru; Masuda, Takatsugu; Itoh, Shinichi; Bourdarot, Frédéric; Regnault, Louis-Pierre; Danilkin, Sergey; Li, Shiliang; Luo, Huiqian

    2018-03-01

    We use inelastic neutron scattering to study the low-energy spin excitations of the 112-type iron pnictide Ca0.82La0.18Fe0.96Ni0.04As2 with bulk superconductivity below Tc=22 K . A two-dimensional spin resonance mode is found around E =11 meV , where the resonance energy is almost temperature independent and linearly scales with Tc along with other iron-based superconductors. Polarized neutron analysis reveals the resonance is nearly isotropic in spin space without any L modulations. Because of the unique monoclinic structure with additional zigzag arsenic chains, the As 4 p orbitals contribute to a three-dimensional hole pocket around the Γ point and an extra electron pocket at the X point. Our results suggest that the energy and momentum distribution of the spin resonance does not directly respond to the kz dependence of the fermiology, and the spin resonance intrinsically is a spin-1 mode from singlet-triplet excitations of the Cooper pairs in the case of weak spin-orbital coupling.

  8. Iron-based alloy and nitridation treatment for PEM fuel cell bipolar plates

    Science.gov (United States)

    Brady, Michael P [Oak Ridge, TN; Yang, Bing [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN

    2010-11-09

    A corrosion resistant electrically conductive component that can be used as a bipolar plate in a PEM fuel cell application is composed of an alloy substrate which has 10-30 wt. % Cr, 0.5 to 7 wt. % V, and base metal being Fe, and a continuous surface layer of chromium nitride and vanadium nitride essentially free of base metal. A oxide layer of chromium vanadium oxide can be disposed between the alloy substrate and the continuous surface nitride layer. A method to prepare the corrosion resistant electrically conductive component involves a two-step nitridization sequence by exposing the alloy to a oxygen containing gas at an elevated temperature, and subsequently exposing the alloy to an oxygen free nitrogen containing gas at an elevated temperature to yield a component where a continuous chromium nitride layer free of iron has formed at the surface.

  9. Calcium-sensitive MRI contrast agents based on superparamagnetic iron oxide nanoparticles and calmodulin.

    Science.gov (United States)

    Atanasijevic, Tatjana; Shusteff, Maxim; Fam, Peter; Jasanoff, Alan

    2006-10-03

    We describe a family of calcium indicators for magnetic resonance imaging (MRI), formed by combining a powerful iron oxide nanoparticle-based contrast mechanism with the versatile calcium-sensing protein calmodulin and its targets. Calcium-dependent protein-protein interactions drive particle clustering and produce up to 5-fold changes in T2 relaxivity, an indication of the sensors' potency. A variant based on conjugates of wild-type calmodulin and the peptide M13 reports concentration changes near 1 microM Ca(2+), suitable for detection of elevated intracellular calcium levels. The midpoint and cooperativity of the response can be tuned by mutating the protein domains that actuate the sensor. Robust MRI signal changes are achieved even at nanomolar particle concentrations (calcium levels. When combined with technologies for cellular delivery of nanoparticulate agents, these sensors and their derivatives may be useful for functional molecular imaging of biological signaling networks in live, opaque specimens.

  10. Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Kaveh Movlaee

    2017-11-01

    Full Text Available Iron oxide nanostructures (IONs in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (biochemical substances.

  11. Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

    Science.gov (United States)

    Movlaee, Kaveh; Ganjali, Mohmmad Reza; Norouzi, Parviz

    2017-01-01

    Iron oxide nanostructures (IONs) in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (bio)chemical substances. PMID:29168771

  12. Depositing Nickel-based Hardfacing to Join Carbon Steel and Cast Iron

    Directory of Open Access Journals (Sweden)

    Tomás Fernández-Columbié

    2016-10-01

    Full Text Available The objective of this investigation is to determine the micro-structural behavior of a joint between cast iron and carbon steel by depositing a nickel-based substrate in the carbon steel. The filler was added through Shielded Metal Arc Welding using Castec 3099 (UTP 8 electrodes while the base materials were joined through Gas Tungsten Arc Welding with ER 70S – A1 bare electrodes. The Schaeffler diagram was used to analyze the chemical composition of the resulting weld beads. The results of the analysis performed on the welded area and the heat influence zone indicated the formation of acicular structures near the welded line when Castec 3099 electrodes are used and the formation of skeletal ferrite on the heat influence zone during the application of this welding process. An austenitic mixture is formed when ER 70S – A1 electrodes are used.

  13. Analysis of Crystal Structure of Fe3O4 Thin Films Based on Iron Sand Growth by Spin Coating Method

    Science.gov (United States)

    Rianto, D.; Yulfriska, N.; Murti, F.; Hidayati, H.; Ramli, R.

    2018-04-01

    Recently, iron sand used as one of base materials in the steel industry. However, the content of iron sand can be used as starting materials in sensor technology in the form of thin films. In this paper, we report the analysis of crystal structure of magnetite thin film based on iron sand from Tiram’s Beach. The magnetic content of sand separated by a permanent magnet, then it was milled at 30 hours milling time. In order to increase the purity of magnetite, it washed after milling using aquades under magnetic separation by a magnet permanent. The thin film has been prepared using iron (III) nitrate by sol–gel technique. The precursor is resulted by dissolving magnetite in oxalic acid and nitric acid. Then, solution of iron (III) nitrate dissolved in ethylene glycol was applied on glass substrates by spin coating. The X-Ray Diffraction is operated thin film characterization. The structure of magnetite has been studied based on X-Ray Peaks that correspond to magnetite content of thin films.

  14. Effect of chromium and phosphorus on the physical properties of iron and titanium-based amorphous metallic alloy films

    Science.gov (United States)

    Distefano, S.; Rameshan, R.; Fitzgerald, D. J.

    1991-01-01

    Amorphous iron and titanium-based alloys containing various amounts of chromium, phosphorus, and boron exhibit high corrosion resistance. Some physical properties of Fe and Ti-based metallic alloy films deposited on a glass substrate by a dc-magnetron sputtering technique are reported. The films were characterized using differential scanning calorimetry, stress analysis, SEM, XRD, SIMS, electron microprobe, and potentiodynamic polarization techniques.

  15. Biostable glucose permeable polymer

    DEFF Research Database (Denmark)

    2017-01-01

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

  16. High Prevalence but Insufficient Treatment of Iron-Deficiency Anemia in Patients with Inflammatory Bowel Disease: Results of a Population-Based Cohort

    Science.gov (United States)

    Ott, Claudia; Liebold, Anne; Takses, Angela; Strauch, Ulrike G.; Obermeier, Florian

    2012-01-01

    Background. Iron-deficiency anemia is described to be a common problem in patients with inflammatory bowel disease (IBD), which is frequently associated with a reduced quality of life. Therefore, the aim of this study is to assess the prevalence of iron deficiency anemia in a population-based cohort at time of first diagnosis and during the early course of the disease. Methods. As far as available, lab values of patients registered in the population-based “Oberpfalz cohort” were screened. In anemic patients, we further investigated all laboratory results to differentiate between iron deficiency and other reasons for anemia. All patients with any kind of anemia were interviewed separately according to symptoms of iron-deficiency anemia and administration of iron. Results. In total, we evaluated hemoglobin values of 279 patients (183 Crohn's disease, 90 ulcerative colitis, and 6 indeterminate colitis). Lab data which allowed further differentiation of the type of anemia were available in 70% of anemic patients, in 34.4% values of iron, ferritin and transferrin saturation had been measured. At time of first diagnosis, an iron-deficiency anemia was diagnosed in 26 of 68 patients with anemia (38.2%, 20 CD, 4 UC, and 2 IC patients), but only 9 patients (34.6%) received subsequent iron therapy. After one year, 27 patients were identified to have an iron-deficiency anemia (19 CD, 8 UC), 20 of them were treated with iron (71.4%). Of 9 patients with proven iron-deficiency anemia at time of first diagnosis and subsequent administration of iron, 5 (55.5%) had iron-deficiency anemia despite permanent treatment after one year. In total, 38 patients (54.3%) did not receive any iron substitution at all despite of proven iron-deficiency anemia, and only 13 patients of 74 patients were treated with intravenous iron (17.6%). Conclusion. We found a high prevalence of iron-deficiency anemia at different points during the early course of disease in this population-based cohort of

  17. Transport Measurements and Synchrotron-Based X-Ray Absorption Spectroscopy of Iron Silicon Germanide Grown by Molecular Beam Epitaxy

    Science.gov (United States)

    Elmarhoumi, Nader; Cottier, Ryan; Merchan, Greg; Roy, Amitava; Lohn, Chris; Geisler, Heike; Ventrice, Carl, Jr.; Golding, Terry

    2009-03-01

    Some of the iron-based metal silicide and germanide phases have been predicted to be direct band gap semiconductors. Therefore, they show promise for use as optoelectronic materials. We have used synchrotron-based x-ray absorption spectroscopy to study the structure of iron silicon germanide films grown by molecular beam epitaxy. A series of Fe(Si1-xGex)2 thin films (2000 -- 8000å) with a nominal Ge concentration of up to x = 0.04 have been grown. X-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) measurements have been performed on the films. The nearest neighbor co-ordination corresponding to the β-FeSi2 phase of iron silicide provides the best fit with the EXAFS data. Temperature dependent (20 coefficient was calculated. Results suggest semiconducting behavior of the films which is consistent with the EXAFS results.

  18. Tailoring the properties of a zero-valent iron-based composite by mechanochemistry for nitrophenols degradation in wastewaters.

    Science.gov (United States)

    Cagnetta, Giovanni; Huang, Jun; Lomovskiy, Igor O; Yu, Gang

    2017-11-01

    Zero-valent iron (ZVI) is a valuable material for environmental remediation, because of its safeness, large availability, and inexpensiveness. Moreover, its reactivity can be improved by addition of (nano-) particles of other elements such as noble metals. However, common preparation methods for this kind of iron-based composites involve wet precipitation of noble metal salt precursors, so they are often expensive and not green. Mechanochemical procedures can provide a solvent-free alternative, even at a large scale. The present study demonstrates that it is possible to tailor functional properties of ZVI-based materials, utilizing high-energy ball milling. All main preparation parameters are investigated and discussed. Specifically, a copper-carbon-iron ternary composite was prepared for fast degradation of 4-nitrophenol (utilized as model pollutant) to 4-aminophenol and other phenolic compounds. Copper and carbon are purposely chosen to insert specific properties to the composite: Copper acts as efficient nano-cathode that enhances electron transfer from iron to 4-nitrophenol, while carbon protects the iron surface from fast oxidation in open air. In this way, the reactive material can rapidly reduce high concentration of nitrophenols in water, it does not require acid washing to be activated, and can be stored in open air for one week without any significant activity loss.

  19. An approach for the fatigue estimation of porous cast iron based on non-destructive testing results

    Directory of Open Access Journals (Sweden)

    Heinrietz André

    2014-06-01

    Full Text Available Big cast iron components made of spheroidal cast iron allow constructing big structures such as stone mills, engine blocks or wind mills with acceptable expenses. Thus, in economically optimized cast processes pores cannot be always prevented in thick walled cast iron components and these components are often rejected because of safety reasons. On the one hand the fatigue performance of high loadable spheroidal cast iron components is reduced significantly by the presence of local porosities which has been pointed out in the past. On the other hand concepts for the fatigue estimation based on fracture mechanics which take the size and localization of the defect into account can lead to erroneous estimations because the defect is modelled as a crack. The challenge of an estimation method is to derive a fatigue life without the necessity to perform component tests. In the contribution an estimation method is presented which is able to determine the fatigue strength of a material volume taking the pores into account. The method can be applied based on data from computer tomographic X-ray (CT or Sampling Phased Array (SPA ultrasonic analyses. The method is presented for three spheroidal cast iron types: ferritic GJS-400-18, ferritic GJS-450-15 with high silicon content and perlitic GJS-700-3.

  20. Contribution of macrophages in the contrast loss in iron oxide-based MRI cancer cell tracking studies

    Science.gov (United States)

    Danhier, Pierre; Deumer, Gladys; Joudiou, Nicolas; Bouzin, Caroline; Levêque, Philippe; Haufroid, Vincent; Jordan, Bénédicte F.; Feron, Olivier; Sonveaux, Pierre; Gallez, Bernard

    2017-01-01

    Magnetic resonance imaging (MRI) cell tracking of cancer cells labeled with superparamagnetic iron oxides (SPIO) allows visualizing metastatic cells in preclinical models. However, previous works showed that the signal void induced by SPIO on T2(*)-weighted images decreased over time. Here, we aim at characterizing the fate of iron oxide nanoparticles used in cell tracking studies and the role of macrophages in SPIO metabolism. In vivo MRI cell tracking of SPIO positive 4T1 breast cancer cells revealed a quick loss of T2* contrast after injection. We next took advantage of electron paramagnetic resonance (EPR) spectroscopy and inductively coupled plasma mass spectroscopy (ICP-MS) for characterizing the evolution of superparamagnetic and non-superparamagnetic iron pools in 4T1 breast cancer cells and J774 macrophages after SPIO labeling. These in vitro experiments and histology studies performed on 4T1 tumors highlighted the quick degradation of iron oxides by macrophages in SPIO-based cell tracking experiments. In conclusion, the release of SPIO by dying cancer cells and the subsequent uptake of iron oxides by tumor macrophages are limiting factors in MRI cell tracking experiments that plead for the use of (MR) reporter-gene based imaging methods for the long-term tracking of metastatic cells. PMID:28467814

  1. Iron telluride nanorods-based system for the detection of total mercury in blood

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Prathik; Lin, Zong-Hong [Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan (China); Liang, Chi-Te [Department of Physics, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan (China); Chang, Huan-Tsung, E-mail: changht@ntu.edu.tw [Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan (China)

    2012-12-15

    Graphical abstract: Elucidation of the detection of mercury using iron telluride nanorods (FeTe NRs), and dose-response curve for varying concentrations of Hg{sup 2+}. Highlights: Black-Right-Pointing-Pointer Iron telluride nanorods (FeTe NRs) are prepared from tellurium nanowires (Te NWs). Black-Right-Pointing-Pointer Mercury telluride nanorods (HgTe NRs) form by cation exchange reaction of FeTe NRs. Black-Right-Pointing-Pointer Fe{sup 2+} ions released catalyze the oxidation of ABTS by H{sub 2}O{sub 2}. Black-Right-Pointing-Pointer Mercury is effectively determined in blood with an LOD of 1.31 nM at S/N ratio 3. - Abstract: We have developed a simple, colorimetric iron telluride (FeTe) nanorods (NRs) based system for the detection of mercury, mainly based on the cation exchange reaction between FeTe NRs and Hg{sup 2+}. FeTe NRs (length, 105 {+-} 21 nm) react with Hg{sup 2+} to form HgTe NRs (length, 112 {+-} 26 nm) and consequently release Fe{sup 2+} ions that catalyzes the oxidation between a peroxidase substrate 2,2 Prime -azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) and H{sub 2}O{sub 2}. The concentration of Fe{sup 2+} and thereby Hg{sup 2+} can be determined by measuring the absorbance of the ABTS oxidized product at 418 nm. This approach allows the detection of Hg{sup 2+}, with a limit of detection of 1.31 nM at a signal-to-noise ratio 3 and a linear range 5-100 nM (R{sup 2} = 0.99). The low-cost, simple, sensitive, and reproducible assay has been validated for the detection of Hg{sup 2+} in a blood sample (SRM 955c), with the result being in good agreement with that provided by National Institute of Standards and Technology.

  2. Water based suspensions of iron oxide obtained by laser target evaporation for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Novoselova, I.P. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Immanuel Kant Baltic Federal University, Science and Technology Park “Fabrica”, Gaidara St. 6, 236022 Kaliningrad (Russian Federation); Safronov, A.P. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Institute of Electrophysics UD RAS, Amundsena St. 106, 620016 Yekaterinburg (Russian Federation); Samatov, O.M. [Institute of Electrophysics UD RAS, Amundsena St. 106, 620016 Yekaterinburg (Russian Federation); Beketov, I.V.; Medvedev, A.I. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Institute of Electrophysics UD RAS, Amundsena St. 106, 620016 Yekaterinburg (Russian Federation); Kurlyandskaya, G.V. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Universidad del País Vasco, UPV/EHU, Dpto. de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain)

    2016-10-01

    In this work spherical magnetic nanoparticles (MNPs) of iron oxide were obtained by laser target evaporation technique (LTE). Water based suspensions were prepared on the basis of obtained MNPs and their properties were also studied including inductive heat capacity. Their structure and properties were studied by a number of techniques including magnetometry and heat capacity measurements. Magnetic induction heating experiment show the specific loss power (SLP) value in the narrow range from 1.30 to 1.45 W/g for all samples under consideration when using alternating magnetic field of 1.7 kA/m and frequency of 210 kHz. These parameters insure that LTE MNPs are interesting materials promising for magnetic fluid hyperthermia. - Highlights: • Spheric oxide nanoparticles obtained by productive laser target evaporation method. • Experiment shows the specific loss power value in the narrow range for all samples. • Obtained results insure these objects as interesting material for hyperthermia.

  3. Nematic fluctuations, fermiology and the pairing potential in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kretzschmar, Florian

    2015-08-18

    The thesis comprises a systematic study on the doping, temperature and momentum dependent electron dynamics in iron-based superconductors using inelastic light scattering. The observation of Bardasis-Schrieffer modes in the excitation spectrum of superconducting Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2} is reported and the energy and symmetry dependence of the modes are analyzed. The analysis yields the identification of a strong subdominant component of the interaction potential V(k,k{sup '}). Strong nematic fluctuations are investigated in Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2}. The nature of the fluctuations and the origin of nematicity in Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} are identified.

  4. Electronic Raman spectra in iron-based superconductors with two-orbital model

    International Nuclear Information System (INIS)

    Lu Hongyan; Wang Da; Chen San; Wang Wei; Gong Pifeng

    2011-01-01

    Electronic Raman spectra were calculated in orbital space in a microscopic theory. Both Raman spectra and spectra weight were presented. Raman spectra for the gap symmetries are different from each other. The results can help decide the gap symmetry by comparing with experiments. Electronic Raman spectra in iron-based superconductors with two-orbital model is discussed. In the orbital space, some possible pairing symmetries of the gap are selected. To further discriminate them, electronic Raman spectra and spectra weight at Fermi surface (FS) which helps understand the Raman spectra are calculated in each case. From the low energy threshold, the number of Raman peaks, and the low frequency power law behavior, we can judge whether it is full gap or nodal gap, and even one gap or multi-gaps. The results provide useful predictions for comparison with experiments.

  5. Water based suspensions of iron oxide obtained by laser target evaporation for biomedical applications

    International Nuclear Information System (INIS)

    Novoselova, I.P.; Safronov, A.P.; Samatov, O.M.; Beketov, I.V.; Medvedev, A.I.; Kurlyandskaya, G.V.

    2016-01-01

    In this work spherical magnetic nanoparticles (MNPs) of iron oxide were obtained by laser target evaporation technique (LTE). Water based suspensions were prepared on the basis of obtained MNPs and their properties were also studied including inductive heat capacity. Their structure and properties were studied by a number of techniques including magnetometry and heat capacity measurements. Magnetic induction heating experiment show the specific loss power (SLP) value in the narrow range from 1.30 to 1.45 W/g for all samples under consideration when using alternating magnetic field of 1.7 kA/m and frequency of 210 kHz. These parameters insure that LTE MNPs are interesting materials promising for magnetic fluid hyperthermia. - Highlights: • Spheric oxide nanoparticles obtained by productive laser target evaporation method. • Experiment shows the specific loss power value in the narrow range for all samples. • Obtained results insure these objects as interesting material for hyperthermia.

  6. Single molecular switch based on thiol tethered iron(II)clathrochelate on gold

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Subramanian [Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Tuwima 10, 10-747 Olsztyn (Poland); Voloshin, Yan Z. [Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 119991 Moscow (Russian Federation); Radecka, Hanna [Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Tuwima 10, 10-747 Olsztyn (Poland); Radecki, Jerzy [Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Tuwima 10, 10-747 Olsztyn (Poland)], E-mail: radecki@pan.olsztyn.pl

    2009-09-30

    Molecular electronics has been associated with high density nano-electronic devices. Developments of molecular electronic devices were based on reversible switching of molecules between the two conductive states. In this paper, self-assembled monolayers of dodecanethiol (DDT) and thiol tethered iron(II)clathrochelate (IC) have been prepared on gold film. The electrochemical and electronic properties of IC molecules inserted into the dodecanethiol monolayer (IC-DDT SAM) were investigated using voltammetric, electrochemical impedance spectroscopy (EIS), scanning tunneling microscopy (STM) and cross-wire tunneling measurements. The voltage triggered switching behaviour of IC molecules on mixed SAM was demonstrated. Deposition of polyaniline on the redox sites of IC-DDT SAM using electrochemical polymerization of aniline was performed in order to confirm that this monolayer acts as nano-patterned semiconducting electrode surface.

  7. Development of iron-based nanoparticles for Cr(VI removal from drinking water

    Directory of Open Access Journals (Sweden)

    Vourlias G.

    2013-01-01

    Full Text Available A great deal of research over recent decades has been motivated by the requirement to lower the concentration of chromium in drinking water. This study has been conducted to determine the feasibility of iron-based nanoparticles for chromium removal from contaminated water. Single Fe, Fe3O4 and binary Fe/Fe3O4 nanoparticles were grown at the 45-80 nm size range using the solar physical vapor deposition technique and tested as potential hexavalent chromium removing agents from aqueous solutions. Due to their higher electron donation ability compared to the Fe3O4 ones, single Fe nanoparticles exhibited the highest Cr(VI removal capacity of more than 3 µg/mg while maintaining a residual concentration 50 µg/L, equal to the regulation limit for drinking water. In combination to their facile and fast magnetic separation, the applicability of the studied particles in water treatment facilities should be considered.

  8. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, Gy.L.; Bizzeti, A.; Choumilov, E.; Civinini, C; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malinin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-01-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO2 (100%) and CF4/CO2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author) 23 refs

  9. Electron beam test of an iron/gas calorimeter based on ceramic parallel plate chambers

    International Nuclear Information System (INIS)

    Arefiev, A.; Bencze, G.L.; Bizzeti, A.; choumilov, E.; Civinini, C.; Dalla Santa, F.; D'Alessandro, R.; Ferrando, A.; Fouz, M.C.; Herve, A.; Iglesias, A.; Ivochkin, V.; Josa, M.I.; Maggi, F.; Malininin, A.; Meschini, M.; Pojidaev, V.; Radermacher, E.; Salicio, J.M.

    1995-12-01

    The baseline option for the very forward calorimetry in the CMS experiment is an iron/gas calorimeter based on parallel plate chambers. A small prototype module of such a calorimeter, has been tested using electrons of 5 to 100 GeV/c momentum with various high voltages and two gases: CO 2 (100%) and CF 4 /CO 2 (80/20), at atmospheric pressure. The collected charge has been measured as a function of the high voltage and of the electron energy. The energy resolution has also been measured. Comparisons have been made with Monte-Carlo predictions. Agreement between data an simulation allows to make and estimation of the expected performance of a full size calorimeter. (Author)

  10. Oxidation behavior of austenitic iron-base ODS alloy in supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Behnamian, Y.; Dong, Z.; Zahiri, R.; Kohandehghan, A.; Mitlin, D., E-mail: behnamia@ualberta.ca, E-mail: zdong@ualberta.ca, E-mail: kohandeh@ualberta.ca, E-mail: rzahiris@ualberta.ca, E-mail: dave.mitlin@ualberta.ca [Univ. of Alberta, Edmondon, AB (Canada); Zhou, Z., E-mail: zhouzhj@mater.ustb.edu.cn [Univ. of Science and Tech. Beijing, Beijing (China); Chen, W.; Luo, J., E-mail: weixing.chen@ualberta.ca, E-mail: Jingli.luo@ualberta.ca [Univ. of Alberta, Edmonton, AB (Canada); Zheng, W., E-mail: wenyue@nrcan.gc.ca [Natural Resources Canada, Canmet MATERIALS, Hamilton, ON (Canada); Guzonas, D. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

    2014-07-01

    In this study, the effect of exposure time on the corrosion of the 304 stainless steel based oxide dispersion strengthened alloy, SS304ODS, in supercritical water was investigated at 650 {sup o}C with constant dissolved oxygen concentration. The results show that the oxidation of SS304ODS in supercritical water followed a parabolic law at 650 {sup o}C. Discontinuous oxide scale with two distinct layers has formed after 550 hours. The inner layer was chromium-rich while the outer layer was iron-rich (Magnetite). The oxide islands grow with increasing the exposure time. With increasing exposure time, the quantity of oxide islands increased in which major preferential growth along oxide-substrate interface was observed. The possible mechanism of SS304ODS oxidation in supercritical water was also discussed. (author)

  11. Role of samarium additions on the shape memory behavior of iron based alloys

    International Nuclear Information System (INIS)

    Shakoor, R.A.; Khalid, F. Ahmad; Kang, Kisuk

    2011-01-01

    Research highlights: → The effect of samarium contents on shape memory behavior has been studied. → Addition of samarium increases the strength, c/a ratio and ε (hcp martensite). → Addition of samarium retards the nucleation of α (bcc martensite). → Improvement in shape memory effect with the increase in samarium contents. - Abstract: The effect of samarium contents on shape memory behavior of iron based shape memory alloys has been studied. It is found that the strength of the alloys increases with the increase in samarium contents. This effect can be attributed to the solid solution strengthening of austenite by samarium addition. It is also noticed that the shape memory effect increases with the increase in samarium contents. This improvement in shape memory effect presumably can be regarded as the effect of improvement in strength, increase in c/a ratio and obstruction of nucleation of α in the microstructure.

  12. Magnetism, Superconductivity, and Spontaneous Orbital Order in Iron-Based Superconductors: Which Comes First and Why?

    Directory of Open Access Journals (Sweden)

    Andrey V. Chubukov

    2016-12-01

    Full Text Available Magnetism and nematic order are the two nonsuperconducting orders observed in iron-based superconductors. To elucidate the interplay between them and ultimately unveil the pairing mechanism, several models have been investigated. In models with quenched orbital degrees of freedom, magnetic fluctuations promote stripe magnetism, which induces orbital order. In models with quenched spin degrees of freedom, charge fluctuations promote spontaneous orbital order, which induces stripe magnetism. Here, we develop an unbiased approach, in which we treat magnetic and orbital fluctuations on equal footing. Key to our approach is the inclusion of the orbital character of the low-energy electronic states into renormalization group (RG analysis. We analyze the RG flow of the couplings and argue that the same magnetic fluctuations, which are known to promote s^{+-} superconductivity, also promote an attraction in the orbital channel, even if the bare orbital interaction is repulsive. We next analyze the RG flow of the susceptibilities and show that, if all Fermi pockets are small, the system first develops a spontaneous orbital order, then s^{+-} superconductivity, and magnetic order does not develop down to T=0. We argue that this scenario applies to FeSe. In systems with larger pockets, such as BaFe_{2}As_{2} and LaFeAsO, we find that the leading instability is either towards a spin-density wave or superconductivity. We argue that in this situation nematic order is caused by composite spin fluctuations and is vestigial to stripe magnetism. Our results provide a unifying description of different iron-based materials.

  13. Long-term effects of the iron-based phosphate binder, sucroferric oxyhydroxide, in dialysis patients.

    Science.gov (United States)

    Floege, Jürgen; Covic, Adrian C; Ketteler, Markus; Mann, Johannes F E; Rastogi, Anjay; Spinowitz, Bruce; Chong, Edward M F; Gaillard, Sylvain; Lisk, Laura J; Sprague, Stuart M

    2015-06-01

    Hyperphosphatemia necessitates the use of phosphate binders in most dialysis patients. Long-term efficacy and tolerability of the iron-based phosphate binder, sucroferric oxyhydroxide (previously known as PA21), was compared with that of sevelamer carbonate (sevelamer) in an open-label Phase III extension study. In the initial Phase III study, hemo- or peritoneal dialysis patients with hyperphosphatemia were randomized 2:1 to receive sucroferric oxyhydroxide 1.0-3.0 g/day (2-6 tablets/day; n = 710) or sevelamer 2.4-14.4 g/day (3-18 tablets/day; n = 349) for 24 weeks. Eligible patients could enter the 28-week extension study, continuing the same treatment and dose they were receiving at the end of the initial study. Overall, 644 patients were available for efficacy analysis (n = 384 sucroferric oxyhydroxide; n = 260 sevelamer). Serum phosphorus concentrations were maintained during the extension study. Mean ± standard deviation (SD) change in serum phosphorus concentrations from extension study baseline to Week 52 end point was 0.02 ± 0.52 mmol/L with sucroferric oxyhydroxide and 0.09 ± 0.58 mmol/L with sevelamer. Mean serum phosphorus concentrations remained within Kidney Disease Outcomes Quality Initiative target range (1.13-1.78 mmol/L) for both treatment groups. Mean (SD) daily tablet number over the 28-week extension study was lower for sucroferric oxyhydroxide (4.0 ± 1.5) versus sevelamer (10.1 ± 6.6). Patient adherence was 86.2% with sucroferric oxyhydroxide versus 76.9% with sevelamer. Mean serum ferritin concentrations increased over the extension study in both treatment groups, but transferrin saturation (TSAT), iron and hemoglobin concentrations were generally stable. Gastrointestinal-related adverse events were similar and occurred early with both treatments, but decreased over time. The serum phosphorus-lowering effect of sucroferric oxyhydroxide was maintained over 1 year and associated with a lower pill burden, compared with sevelamer

  14. Electrochemically Generated cis-Carboxylato-Coordinated Iron(IV) Oxo Acid-Base Congeners as Promiscuous Oxidants of Water Pollutants

    DEFF Research Database (Denmark)

    de Sousa, David P; Miller, Christopher J; Chang, Yingyue

    2017-01-01

    The nonheme iron(IV) oxo complex [FeIV(O)(tpenaH)]2+ and its conjugate base [FeIV(O)(tpena)]+ [tpena- = N,N,N'-tris(2-pyridylmethyl)ethylenediamine-N'-acetate] have been prepared electrochemically in water by bulk electrolysis of solutions prepared from [FeIII2(μ-O)(tpenaH)2](ClO4)4 at potentials...... of the electrochemically generated iron(IV) oxo complexes, in terms of the broad range of substrates examined, represents an important step toward the goal of cost-effective electrocatalytic water purification....

  15. Polymeric precursors method for obtaining pigments based on Inorganic oxides of chromium and iron deposited on TiO2

    International Nuclear Information System (INIS)

    Silva, Everlania M. da; Galvao, Sheila B.; Paskocimas, C.A.

    2011-01-01

    The case study was the use of chromium oxides and iron, as a precursor in the synthesis of inorganic pigments. The synthesis was based on the dissolution of citric acid as a complexing agent, addition of metal oxides, such as ion chromophores; polymerization with ethylene glycol and doping with titanium oxide. Going through pre-calcination, breakdown, calcination at different temperatures (700, 900 and 1100 deg C resulting in pigments: green for pigment and chromium deposited on TiO2, orange for iron on TiO2. The thermal analysis (TG and DTA), evaluated their thermal decompositions, the XRD revealed the formation of crystalline phases such as iron titanate and chrome titanate; SEM showed the formation of hexagonal particles for both oxides. Under the different analysis, one can see the potential stability of pigments and powders, can be proposed its use as pigments in polymers. (author)

  16. Synthesis and characterization of ceramic pigments based on oxides of chromium and iron, on TiO2

    International Nuclear Information System (INIS)

    Silva, E.M. da; Galvao, S.B.; Paskocimas, C.A.

    2011-01-01

    This work used oxides of chromium and iron, as precursors of the synthesis of ceramic pigments. The synthesis is based on the dissolution of citric acid as a complexing agent, addition of metal oxides, such as ion chromophores; polymerization with ethylene glycol and doping with titanium oxide. Passing through pre-calcination, breakdown, calcination at different temperatures (900 and 1100 ° C), resulting in pigments: green for pigment chrome deposited on TiO 2 and orange for iron on TiO 2 . Noticing an increase in the opacity with increasing temperature. The thermal analysis (TG and DTA), evaluated their thermal behavior, the XRD revealed the formation of crystalline phases as Iron Titanate and Chrome Titanate; SEM showed the formation of hexagonal particles for both oxides. Thus, the synthesized oxides were within the requirements for application as ceramic pigments. (author)

  17. Size and Promoter Effects on Stability of Carbon-Nanofiber-Supported Iron-Based Fischer-Tropsch Catalysts

    NARCIS (Netherlands)

    Xie, Jingxiu; Torres Galvis, Hirsa; Koeken, Ard C J; Kirilin, Alexey; Dugulan, A Iulian; Ruitenbeek, Matthijs; de Jong, Krijn P

    2016-01-01

    The Fischer-Tropsch Synthesis converts synthesis gas from alternative carbon resources, including natural gas, coal, and biomass, to hydrocarbons used as fuels or chemicals. In particular, iron-based catalysts at elevated temperatures favor the selective production of C2-C4 olefins, which are

  18. Moessbauer study on the formation process of Fe-K composition in iron-based catalyst for dehydrogenation of ethylbenzene

    International Nuclear Information System (INIS)

    Jiang Keyu; Zhao Zhenjie; Yang Xielong

    2001-01-01

    Fe-K spinel structure is the predecessor of active phase of potassium promoted iron-based catalyst for dehydrogenation of ethylbenzene. Moessbauer spectroscopy has been used to study the formation process of Fe-K spinel structure which depends on the catalyst composition and preparing condition. The results may prove useful for production of industrial catalyst

  19. Sequential Proton Loss Electron Transfer in Deactivation of Iron(IV) Binding Protein by Tyrosine Based Food Components

    DEFF Research Database (Denmark)

    Tang, Ning; Skibsted, Leif Horsfelt

    2017-01-01

    The iron(IV) binding protein ferrylmyoglobin, MbFe(IV)=O, was found to be reduced by tyrosine based food components in aqueous solution through a sequential proton loss electron transfer reaction mechanism without binding to the protein as confirmed by isothermal titration calorimetry. Dopamine a...

  20. Constructal design of a blast furnace iron-making process based on multi-objective optimization

    International Nuclear Information System (INIS)

    Liu, Xiong; Chen, Lingen; Feng, Huijun; Qin, Xiaoyong; Sun, Fengrui

    2016-01-01

    For the fixed total raw material cost and based on constructal theory and finite time thermodynamics, a BFIM (blast furnace iron-making) process is optimized by taking a complex function as optimization objective. The complex function is integrated with HM (hot metal) yield and useful energy of the BF (blast furnace). The optimal cost distribution of raw materials (namely “generalized optimal construct”) is obtained. The effects of some parameters, such as oxygen enrichment, blast temperature and pulverized coal dosage, on the optimization results are analyzed. The results show that the HM yield, useful energy and complex function are, respectively, increased by 3.13%, 2.66% and 2.90% after generalized constructal optimization. The utilization efficiencies of the BFG (blast furnace gas) and slag are 41.3% and 57.1%, respectively, which means that the utilization potentials of the BFG and slag can be further exploited. Increasing pulverized coal dosage and decreasing the agglomerate ratio can increase the complex function. The performance the BFIM process can be improved by adjusting the oxygen enrichment, blast temperature, blast dosage, pressure ratio of the Brayton cycle's air compressor and relative pressure drop of the air compressor inlet to their optimal values, respectively, which are new findings of this paper. - Highlights: • Constructal optimization of a blast furnace iron-making process is performed. • Finite time thermodynamic model of open Brayton cycle is adopted. • Weighting function is taken as optimization objective. • Optimal cost distribution of the raw materials is obtained.

  1. Reactivity of tris(acetylacetonato) iron(III) with tridentate [ONO] donor Schiff base as an access to newer mixed-ligand iron(III) complexes

    Science.gov (United States)

    Bhattacharjee, Chira R.; Goswami, Pankaj; Pramanik, Harun A. R.; Paul, Pradip C.; Mondal, Paritosh

    2011-05-01

    Two new mixed-ligand iron(III) complexes, [Fe(L n)(acac)(C 2H 5OH)] incorporating coordinated ethanol from the reaction solvent were accessed from the reaction of [Fe(acac) 3] with [ONO] donor dibasic tridentate unsymmetrical Schiff base ligands derived from condensation of 2-hydroxy-1-napthaldehyde with 2-aminophenol (H 2L 1) or 2-aminobenzoic acid (H 2L 2). The thermal study (TGA-DTA) provided evidence for weakly bound ethanol which is readily substituted by neutral N-donor molecule imidazole, benzimidazole or pyridine to produce an array of newer complexes, [Fe(L n)(acac)X] ( n = 1, 2; X = Im, Bim, Py). The compounds were characterized by elemental analyses, FT-IR, UV-vis, solution electrical conductivity, FAB mass, 1H and 13C NMR spectroscopy. Room temperature magnetic susceptibility measurements ( μeff ˜ 5.8 B.M.) are consistent with spin-free octahedral iron(III) complexes. Cyclic voltammetry of ethanol complexes revealed a quasi-reversible one electron redox response (Δ Ep > 100 mV) for the Fe(III)/Fe(II) couple. Low half wave redox potential ( E1/2) values suggested easy redox susceptibility. The ground state geometries of the ethanol and imidazole complexes have been ascertained to be distorted octahedral by density functional theory using DMol3 program at BLYP/DNP level.

  2. Defining clogging potential for permeable concrete.

    Science.gov (United States)

    Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

    2018-08-15

    Permeable concrete is used to reduce urban flooding as it allows water to flow through normally impermeable infrastructure. It is prone to clogging by particulate matter and predicting the long-term performance of permeable concrete is challenging as there is currently no reliable means of characterising clogging potential. This paper reports on the performance of a range of laboratory-prepared and commercial permeable concretes, close packed glass spheres and aggregate particles of varying size, exposed to different clogging methods to understand this phenomena. New methods were developed to study clogging and define clogging potential. The tests involved applying flowing water containing sand and/or clay in cycles, and measuring the change in permeability. Substantial permeability reductions were observed in all samples, particularly when exposed to sand and clay simultaneously. Three methods were used to define clogging potential based on measuring the initial permeability decay, half-life cycle and number of cycles to full clogging. We show for the first time strong linear correlations between these parameters for a wide range of samples, indicating their use for service-life prediction. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Study of solubility of akaline earth metals in liquid iron and in alloys on its base

    International Nuclear Information System (INIS)

    Ageev, Yu.A.; Archugov, S.A.

    1985-01-01

    Solubility of magnesium, calcium, strontium and barium in liquid iron and its alloys with aluminium, silicon, nickel, chromium and carbon at 1600 deg C has been measured. Interaction parameters taking account of the effect of added elements on alkaline earth metal solubility in liquid iron have been estimated

  4. THE EFFECT OF PREPARATION CONDITIONS OF RAPIDLY SOLIDIFIED IRON BASED GRANULES ON PROPERTIES OF COMPOSITE MATERIAL FORMED BY CASTING TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    A. S. Kalinichenko

    2017-01-01

    Full Text Available The variety of requirements for friction pairs requires the development of different technologies for the production of tribological materials with reference to the operation modes. Composite materials obtained by the casting technology have been successfully applied for the normalization of the thermomechanical state of the steam turbines. These composites consist of the matrix based on copper alloys reinforced with cast iron granules. Because the structure and properties of cast iron are determined by the conditions of their production studies have been conducted on determination of preparation conditions on grain structure and properties of the synthesized composite material. Using an upgraded unit for production of granules technological regimes were determined providing narrow fractional composition. It has been found that granules formed are characterized with typical microstructure of white cast iron containing perlite and ledeburite. Microhardness of pilot cast iron granules is characterized by high values (from 7450 up to 9450 MPa and depends on the size of the fraction. Composite materials obtained using experimental granules had a microhardness of the reinforcing cast iron granules about 3500 MPa, and a bronze matrix – 1220 MPa, which is higher than the hardness of the composite material obtained by using the annealed DCL-1granules (2250 MPa. Metal base of experimental granules in the composite material has the structure of perlitic ductile iron with inclusions of ferrite not exceeding 10–15% and set around a flocculent graphite. As a result, the increase of physical-mechanical properties of finished products made of composite material is observed. 

  5. Critical determinant of intestinal permeability and oral bioavailability of pegylated all trans-retinoic acid prodrug-based nanomicelles: Chain length of poly (ethylene glycol) corona.

    Science.gov (United States)

    Li, Zhenbao; Han, Xiaopeng; Zhai, Yinglei; Lian, He; Zhang, Dong; Zhang, Wenjuan; Wang, Yongjun; He, Zhonggui; Liu, Zheng; Sun, Jin

    2015-06-01

    Pegylation method is widely used to prolong the blood circulation time of proteins and nanoparticles after intravenous administration, but the effect of surface poly (ethylene glycol) (PEG) chain length on oral absorption of the pegylated nanoparticles is poorly reported. The aim of our study was to investigate the influence of PEG corona chain length on membrane permeability and oral bioavailability of the amphiphilic pegylated prodrug-based nanomicelles, taking all trans-retinoic acid (ATRA) as a model drug. The amphiphilic ATRA-PEG conjugates were synthesized by esterification reaction between all trans-retinoic acid and mPEGs (mPEG500, mPEG1000, mPEG2000, and mPEG5000). The conjugates could self-assemble in aqueous medium to form nanomicelles by emulsion-solvent evaporation method. The resultant nanomicelles were in spherical shape with an average diameter of 13-20 nm. The drug loading efficiency of ATRA-PEG500, ATRA-PEG1000, ATRA-PEG2000, and ATRA-PEG5000 was about 38.4, 26.6, 13.1, and 5.68 wt%, respectively. With PEG chain length ranging from 500 to 5000, ATRA-PEG nanomicelles exhibited a bell shape of chemical stability in different pH buffers, intestinal homogenate and plasma. More importantly, they were all rapidly hydrolyzed into the parent drug in hepatic homogenate, with the half-time values being 0.3-0.4h. In comparison to ATRA solution and ATRA prodrug-based nanomicelles, ATRA-PEG1000 showed the highest intestinal permeability. After oral administration, ATRA-PEG2000 and ATRA-PEG5000 nanomicelles were not nearly absorbed, while the oral bioavailability of ATRA-PEG500 and ATRA-PEG1000 demonstrated about 1.2- and 2.0-fold higher than ATRA solution. Our results indicated that PEG1000 chain length of ATRA-PEG prodrug nanomicelles has the optimal oral bioavailability probably due to improved stability and balanced mucus penetration capability and cell binding, and that the PEG chain length on a surface of nanoparticles cannot exceed a key threshold with

  6. PREFACE: Celebrating 100 years of superconductivity: special issue on the iron-based superconductors Celebrating 100 years of superconductivity: special issue on the iron-based superconductors

    Science.gov (United States)

    Crabtree, George; Greene, Laura; Johnson, Peter

    2011-12-01

    In honor of this year's 100th anniversary of the discovery of superconductivity, this special issue of Reports on Progress in Physics is a dedicated issue to the 'iron-based superconductors'—a new class of high-temperature superconductors that were discovered in 2008. This is the first time the journal has generated a 'theme issue', and we provide this to the community to provide a 'snapshot' of the present status, both for researchers working in this fast-paced field, and for the general physics community. Reports on Progress in Physics publishes three classes of articles—comprehensive full Review Articles, Key Issues Reviews and, most recently, Reports on Progress articles that recount the current status of a rapidly evolving field, befitting of the articles in this special issue. It has been an exciting year for superconductivity—there have been numerous celebrations for this centenary recounting the fascinating history of this field, from seven Nobel prizes to life-saving discoveries that brought us medically useful magnetic resonance imaging. The discovery of a completely new class of high-temperature superconductors, whose mechanism remains as elusive as the cuprates discovered in 1986, has injected a new vitality into this field, and this year those new to the field were provided with the opportunity of interacting with those who have enjoyed a long history in superconductivity. Furthermore, as high-density current carriers with little or no power loss, high-temperature superconductors offer unique solutions to fundamental grid challenges of the 21st century and hold great promise in addressing our global energy challenges. The complexity and promise of these materials has caused our community to more freely share our ideas and results than ever before, and it is gratifying to see how we have grown into an enthusiastic global network to advance the field. This invited collection is true to this agenda and we are delighted to have received contributions

  7. Ab-initio simulations of pressure effects on structural and electronic properties of iron based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tomic, Milan

    2013-07-01

    The ab-initio molecular dynamics framework has been the cornerstone of computational solid state physics in the last few decades. Although it is already a mature field it is still rapidly developing to accommodate the growth in solid state research as well as to efficiently utilize the increase in computing power. Starting from the first principles, the ab-initio molecular dynamics provides essential information about structural and electronic properties of matter under various external conditions. In this thesis we use the ab-initio molecular dynamics to study the behavior of BaFe{sub 2}As{sub 2} and CaFe{sub 2}As{sub 2} under the application of external pressure. BaFe{sub 2}As{sub 2} and CaFe{sub 2}As{sub 2} belong to the family of iron based superconductors which are a novel and promising superconducting materials. The application of pressure is one of two key methods by which electronic and structural properties of iron based superconductors can be modified, the other one being doping (or chemical pressure). In particular, it has been noted that pressure conditions have an important effect, but their exact role is not fully understood. To better understand the effect of different pressure conditions we have performed a series of ab-initio simulations of pressure application. In order to apply the pressure with arbitrary stress tensor we have developed a method based on the Fast Inertial Relaxation Engine, whereby the unit cell and the atomic positions are evolved according to the metadynamical equations of motion. We have found that the application of hydrostatic and c axis uniaxial pressure induces a phase transition from the magnetically ordered orthorhombic phase to the non-magnetic collapsed tetragonal phase in both BaFe{sub 2}As{sub 2} and CaFe{sub 2}As{sub 2}. In the case of BaFe{sub 2}As{sub 2}, an intermediate tetragonal non-magnetic tetragonal phase is observed in addition. Application of the uniaxial pressure parallel to the c axis reduces the

  8. Ab-initio simulations of pressure effects on structural and electronic properties of iron based superconductors

    International Nuclear Information System (INIS)

    Tomic, Milan

    2013-01-01

    The ab-initio molecular dynamics framework has been the cornerstone of computational solid state physics in the last few decades. Although it is already a mature field it is still rapidly developing to accommodate the growth in solid state research as well as to efficiently utilize the increase in computing power. Starting from the first principles, the ab-initio molecular dynamics provides essential information about structural and electronic properties of matter under various external conditions. In this thesis we use the ab-initio molecular dynamics to study the behavior of BaFe 2 As 2 and CaFe 2 As 2 under the application of external pressure. BaFe 2 As 2 and CaFe 2 As 2 belong to the family of iron based superconductors which are a novel and promising superconducting materials. The application of pressure is one of two key methods by which electronic and structural properties of iron based superconductors can be modified, the other one being doping (or chemical pressure). In particular, it has been noted that pressure conditions have an important effect, but their exact role is not fully understood. To better understand the effect of different pressure conditions we have performed a series of ab-initio simulations of pressure application. In order to apply the pressure with arbitrary stress tensor we have developed a method based on the Fast Inertial Relaxation Engine, whereby the unit cell and the atomic positions are evolved according to the metadynamical equations of motion. We have found that the application of hydrostatic and c axis uniaxial pressure induces a phase transition from the magnetically ordered orthorhombic phase to the non-magnetic collapsed tetragonal phase in both BaFe 2 As 2 and CaFe 2 As 2 . In the case of BaFe 2 As 2 , an intermediate tetragonal non-magnetic tetragonal phase is observed in addition. Application of the uniaxial pressure parallel to the c axis reduces the critical pressure of the phase transition by an order of magnitude

  9. Improvement of the Early-Age Compressive Strength, Water Permeability, and Sulfuric Acid Resistance of Scoria-Based Mortars/Concrete Using Limestone Filler

    Directory of Open Access Journals (Sweden)

    Aref Al-Swaidani

    2017-01-01

    Full Text Available Natural pozzolan is being widely used as cement replacement. Despite the economic, ecological, and technical benefits of its adding, it is often associated with shortcomings such as the need of moist-curing for longer time and a lower early strength. This study is an attempt to investigate the effect of adding limestone filler on the compressive strength and durability of mortars/concrete containing scoria. Sixteen types of binders with different replacement levels of scoria (0, 10, 20, and 30% and limestone (0, 5, 10, and 15% were prepared. The development of the compressive strength of mortar/concrete specimens was investigated after 2, 7, 28, and 90 days’ curing. In addition, the acid resistance of the 28 days’ cured mortars was evaluated after 90 days’ exposure to 5% H2SO4. Concrete permeability was also evaluated after 2, 7, 28, and 90 days’ curing. Test results revealed that there was an increase in the early-age compressive strength and a decrease in water penetration depths with adding limestone filler. Contrary to expectation, the best acid resistance to 5% H2SO4 solution was noted in the mortars containing 15% limestone. Based on the results obtained, an empirical equation was derived to predict the compressive strength of mortars.

  10. A Novel Sensor for Monitoring of Iron(III) Ions Based on Porphyrins

    Science.gov (United States)

    Vlascici, Dana; Fagadar-Cosma, Eugenia; Popa, Iuliana; Chiriac, Vlad; Gil-Agusti, Mayte

    2012-01-01

    Three A3B porphyrins with mixed carboxy-, phenoxy-, pyridyl-, and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10−7–1 × 10−1 M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples. PMID:22969395

  11. Prediction of the Iron-Based Polynuclear Magnetic Superhalogens with Pseudohalogen CN as Ligands.

    Science.gov (United States)

    Ding, Li-Ping; Shao, Peng; Lu, Cheng; Zhang, Fang-Hui; Liu, Yun; Mu, Qiang

    2017-07-17

    To explore stable polynuclear magnetic superhalogens, we perform an unbiased structure search for polynuclear iron-based systems based on pseudohalogen ligand CN using the CALYPSO method in conjunction with density functional theory. The superhalogen properties, magnetic properties, and thermodynamic stabilities of neutral and anionic Fe 2 (CN) 5 and Fe 3 (CN) 7 clusters are investigated. The results show that both of the clusters have superhalogen properties due to their electron affinities (EAs) and that vertical detachment energies (VDEs) are significantly larger than those of the chlorine element and their ligand CN. The distribution of the extra electron analysis indicates that the extra electron is aggregated mainly into pseudohalogen ligand CN units in Fe 2 (CN) 5 ¯ and Fe 3 (CN) 7 ¯ cluster. These features contribute significantly to their high EA and VDE. Besides superhalogen properties, these two anionic clusters carry a large magnetic moment just like the Fe 2 F 5 ¯ cluster. Additionally, the thermodynamic stabilities are also discussed by calculating the energy required to fragment the cluster into various smaller stable clusters. It is found that Fe(CN) 2 is the most favorable fragmentation product for anionic Fe 2 (CN) 5 ¯ and Fe 3 (CN) 7 ¯ clusters, and both of the anions are less stable against ejection of Fe atoms than Fe(CN) n-x .

  12. Avoiding the Use of Exhausted Drinking Water Filters: A Filter-Clock Based on Rusting Iron

    Directory of Open Access Journals (Sweden)

    Arnaud Igor Ndé-Tchoupé

    2018-05-01

    Full Text Available Efficient but affordable water treatment technologies are currently sought to solve the prevalent shortage of safe drinking water. Adsorption-based technologies are in the front-line of these efforts. Upon proper design, universally applied materials (e.g., activated carbons, bone chars, metal oxides are able to quantitatively remove inorganic and organic pollutants as well as pathogens from water. Each water filter has a defined removal capacity and must be replaced when this capacity is exhausted. Operational experience has shown that it may be difficult to convince some low-skilled users to buy new filters after a predicted service life. This communication describes the quest to develop a filter-clock to encourage all users to change their filters after the designed service life. A brief discussion on such a filter-clock based on rusting of metallic iron (Fe0 is presented. Integrating such filter-clocks in the design of water filters is regarded as essential for safeguarding public health.

  13. Orbital-selective Mott phase of Cu-substituted iron-based superconductors

    International Nuclear Information System (INIS)

    Liu, Yang; Zhao, Yang-Yang; Song, Yun

    2016-01-01

    We study the phase transition in Cu-substituted iron-based superconductors with a new developed real-space Green’s function method. We find that Cu substitution has strong effect on the orbital-selective Mott transition introduced by the Hund’s rule coupling. The redistribution of the orbital occupancy which is caused by the increase of the Hund’s rule coupling, gives rise to the Mott–Hubbard metal-insulator transition in the half-filled d xy orbital. We also find that more and more electronic states appear inside that Mott gap of the d xy orbital with the increase of Cu substitution, and the in-gap states around the Fermi level are strongly localized at some specific lattice sites. Further, a distinctive phase diagram, obtained for the Cu-substituted Fe-based superconductors, displays an orbital-selective insulating phase, as a result of the cooperative effect of the Hund’s rule coupling and the impurity-induced disorder. (paper)

  14. A novel sensor for monitoring of iron(III) ions based on porphyrins.

    Science.gov (United States)

    Vlascici, Dana; Fagadar-Cosma, Eugenia; Popa, Iuliana; Chiriac, Vlad; Gil-Agusti, Mayte

    2012-01-01

    Three A(3)B porphyrins with mixed carboxy-, phenoxy-, pyridyl-, and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10(-7)-1 × 10(-1) M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples.

  15. Support effects on adsorption and catalytic activation of O2 in single atom iron catalysts with graphene-based substrates.

    Science.gov (United States)

    Gao, Zheng-Yang; Yang, Wei-Jie; Ding, Xun-Lei; Lv, Gang; Yan, Wei-Ping

    2018-03-07

    The adsorption and catalytic activation of O 2 on single atom iron catalysts with graphene-based substrates were investigated systematically by density functional theory calculation. It is found that the support effects of graphene-based substrates have a significant influence on the stability of the single atom catalysts, the adsorption configuration, the electron transfer mechanism, the adsorption energy and the energy barrier. The differences in the stable adsorption configuration of O 2 on single atom iron catalysts with different graphene-based substrates can be well understood by the symmetrical matching principle based on frontier molecular orbital analysis. There are two different mechanisms of electron transfer, in which the Fe atom acts as the electron donor in single vacancy graphene-based substrates while the Fe atom mainly acts as the bridge for electron transfer in double vacancy graphene-based substrates. The Fermi softness and work function are good descriptors of the adsorption energy and they can well reveal the relationship between electronic structure and adsorption energy. This single atom iron catalyst with single vacancy graphene modified by three nitrogen atoms is a promising non-noble metal single atom catalyst in the adsorption and catalytic oxidation of O 2 . Furthermore, the findings can lay the foundation for the further study of graphene-based support effects and provide a guideline for the development and design of new non-noble-metal single atom catalysts.

  16. Tribological behaviour and statistical experimental design of sintered iron-copper based composites

    Science.gov (United States)

    Popescu, Ileana Nicoleta; Ghiţă, Constantin; Bratu, Vasile; Palacios Navarro, Guillermo

    2013-11-01

    The sintered iron-copper based composites for automotive brake pads have a complex composite composition and should have good physical, mechanical and tribological characteristics. In this paper, we obtained frictional composites by Powder Metallurgy (P/M) technique and we have characterized them by microstructural and tribological point of view. The morphology of raw powders was determined by SEM and the surfaces of obtained sintered friction materials were analyzed by ESEM, EDS elemental and compo-images analyses. One lot of samples were tested on a "pin-on-disc" type wear machine under dry sliding conditions, at applied load between 3.5 and 11.5 × 10-1 MPa and 12.5 and 16.9 m/s relative speed in braking point at constant temperature. The other lot of samples were tested on an inertial test stand according to a methodology simulating the real conditions of dry friction, at a contact pressure of 2.5-3 MPa, at 300-1200 rpm. The most important characteristics required for sintered friction materials are high and stable friction coefficient during breaking and also, for high durability in service, must have: low wear, high corrosion resistance, high thermal conductivity, mechanical resistance and thermal stability at elevated temperature. Because of the tribological characteristics importance (wear rate and friction coefficient) of sintered iron-copper based composites, we predicted the tribological behaviour through statistical analysis. For the first lot of samples, the response variables Yi (represented by the wear rate and friction coefficient) have been correlated with x1 and x2 (the code value of applied load and relative speed in braking points, respectively) using a linear factorial design approach. We obtained brake friction materials with improved wear resistance characteristics and high and stable friction coefficients. It has been shown, through experimental data and obtained linear regression equations, that the sintered composites wear rate increases

  17. Synthesis, structures, and dearomatization by deprotonation of iron complexes featuring bipyridine-based PNN pincer ligands.

    Science.gov (United States)

    Zell, Thomas; Langer, Robert; Iron, Mark A; Konstantinovski, Leonid; Shimon, Linda J W; Diskin-Posner, Yael; Leitus, Gregory; Balaraman, Ekambaram; Ben-David, Yehoshoa; Milstein, David

    2013-08-19

    The synthesis and characterization of new iron pincer complexes bearing bipyridine-based PNN ligands is reported. Three phosphine-substituted pincer ligands, namely, the known (t)Bu-PNN (6-((di-tert-butylphosphino)methyl)-2,2'-bipyridine) and the two new (i)Pr-PNN (6-((di-iso-propylphosphino)methyl)-2,2'-bipyridine) and Ph-PNN (6-((diphenylphosphino)methyl)-2,2'-bipyridine) ligands were synthesized and studied in ligation reactions with iron(II) chloride and bromide. These reactions lead to the formation of two types of complexes: mono-chelated neutral complexes of the type [(R-PNN)Fe(X)2] and bis-chelated dicationic complexes of the type [(R-PNN)2Fe](2+). The complexes [(R-PNN)Fe(X)2] (1: R = (t)Bu, X = Cl, 2: R = (t)Bu, X = Br, 3: R = (i)Pr, X = Cl, and 4: R = (i)Pr, X = Br) are readily prepared from reactions of FeX2 with the free R-PNN ligand in a 1:1 ratio. Magnetic susceptibility measurements show that these complexes have a high-spin ground state (S = 2) at room temperature. Employing a 2-fold or higher excess of (i)Pr-PNN, diamagnetic hexacoordinated dicationic complexes of the type [((i)Pr-PNN)2Fe](X)2 (5: X = Cl, and 6: X = Br) are formed. The reactions of Ph-PNN with FeX2 in a 1:1 ratio lead to similar complexes of the type [(Ph-PNN)2Fe](FeX4) (7: X = Cl, and 8: X = Br). Single crystal X-ray studies of 1, 2, 4, 6, and 8 do not indicate electron transfer from the Fe(II) centers to the neutral bipyridine unit based on the determined bond lengths. Density functional theory (DFT) calculations were performed to compare the relative energies of the mono- and bis-chelated complexes. The doubly deprotonated complexes [(R-PNN*)2Fe] (9: R = (i)Pr, and 10: R = Ph) were synthesized by reactions of the dicationic complexes 6 and 8 with KO(t)Bu. The dearomatized nature of the central pyridine of the pincer ligand was established by X-ray diffraction analysis of single crystals of 10. Reactivity studies show that 9 and 10 have a slightly different behavior in

  18. Atomic-scale Visualization of Electronic Nematicity and Cooper Pairing in Iron-based Superconductors

    Science.gov (United States)

    Allan, Milan P.

    2013-03-01

    The mechanism of high-temperature superconductivity in the relatively novel iron-based high-Tc superconductors is unresolved, both in terms of how the phases evolve with doping, and in terms of the actual Cooper pairing process. To explore these issues, we used spectroscopic-imaging scanning tunneling microscopy to study the electronic structure of CaFe2As2 in the antiferromagnetic-orthorhombic `parent' state from which the superconductivity emerges. We discovered and visualized the now widely studied electronic `nematicity' of this phase, whose suppression is associated with the emergence of superconductivity (Science 327, 181, 2010). As subsequent transport experiments discovered a related anisotropic conductance which increases with dopant concentration, the interplay between the electronic structure surrounding each dopant atom, quasiparticle scattering therefrom, and the transport nematicity has become a pivotal focus of research. We find that substituting Co for Fe atoms in underdoped Ca(Fe1-xCox)2As2 generates a dense population of identical and strongly anisotropic impurity states that are distributed randomly but aligned with the antiferromagnetic a-axis. We also demonstrate, by imaging their surrounding interference patterns, that these impurity states scatter quasiparticles and thus influence transport in a highly anisotropic manner (M.P. Allan et al., 2013). Next, we studied the momentum dependence of the energy gaps of iron-based superconductivity, now focusing on LiFeAs. If strong electron-electron interactions mediate the Cooper pairing, then momentum-space anisotropic superconducting energy gaps Δi (k) were predicted by multiple techniques to appear on the different electronic bands i. We introduced intraband Bogoliubov quasiparticle scattering interference (QPI) techniques for the determination of anisotropic energy gaps to test these hypotheses and discovered the anisotropy, magnitude, and relative orientations of the energy gaps on multiple

  19. Permeability-Porosity Relationships of Subduction Zone Sediments

    Science.gov (United States)

    Gamage, K.; Screaton, E.; Bekins, B.; Aiello, I.

    2008-12-01

    Permeability-porosity relationships for sediments from Northern Barbados, Costa Rica, Nankai, and Peru subduction zones were examined based on their sediment type and grain size distribution. Greater correlation was observed between permeability and porosity for siliciclastic sediments, diatom oozes, and nannofossil chalk than for nannofossil oozes. For siliciclastic sediments, grouping of sediments by clay content yields relationships that are generally consistent with results from other marine settings and suggest decreasing permeability for a given porosity as clay content increases. Correction of measured porosities for smectite content generally improves the quality of permeability-porosity relationships. The relationship between permeability and porosity for diatom oozes may be controlled by the amount of clay present in the ooze, causing diatom oozes to behave similarly to siliciclastic sediments. For a given porosity the nannofossil oozes have higher permeability values by 1.5 orders of magnitude than the siliciclastic sediments. However, the use of a permeability-porosity relation may not be appropriate for unconsolidated carbonates such as nannofossil oozes. This study provided insight to the effects of porosity correction for smectite, variations in lithology and grain size in permeability-porosity relationships. However, further progress in delineating controls on permeability will require more careful and better documented permeability tests on characterized samples.

  20. Comparison of regeneration efficiency of strong base anion exchangers fouled by iron and humic acids

    Czech Academy of Sciences Publication Activity Database

    Kus, P.; Kunesova, K.; Šlouf, Miroslav

    2014-01-01

    Roč. 49, č. 15 (2014), s. 2352-2357 ISSN 0149-6395 Institutional support: RVO:61389013 Keywords : regeneration * iron * fouling Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.171, year: 2014

  1. Iron Oxide Nanoparticle-Based Magnetic Ink Development for Fully Printed Tunable Radio-Frequency Devices

    KAUST Repository

    Vaseem, Mohammad; Ghaffar, Farhan A.; Farooqui, Muhammad Fahad; Shamim, Atif

    2018-01-01

    . Functionalized iron oxide nanoparticles are successfully embedded in the SU8 matrix to make a magnetic substrate. The as-fabricated substrate is characterized for its magnetostatic and microwave properties. A frequency tunable printed patch antenna

  2. Colloidosome-based synthesis of a multifunctional nanostructure of silver and hollow iron oxide nanoparticles

    KAUST Repository

    Pan, Yue

    2010-03-16

    Nanoparticles that self-assemble on a liquid-liquid interface serve as the building block for making heterodimeric nanostructures. Specifically, hollow iron oxide nanoparticles within hexane form colloidosomes in the aqueous solution of silver nitrate, and iron oxide exposed to the aqueous phase catalyzes the reduction of silver ions to afford a heterodimer of silver and hollow iron oxide nanoparticles. Transmission electron microscopy, selected area electron diffraction, energy-dispersive X-ray spectrometry, X-ray diffraction, UV-vis spectroscopy, and SQUID were used to characterize the heterodimers. Interestingly, the formation of silver nanoparticles helps the removal of spinglass layer on the hollow iron oxide nanoparticles. This work demonstrates a powerful yet convenient strategy for producing sophisticated, multifunctional nanostructures. © 2010 American Chemical Society.

  3. Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

    International Nuclear Information System (INIS)

    Braga, Tiago P.; Vasconcelos, Igor F.; Sasaki, Jose M.; Fabris, J.D.; Oliveira, Diana Q.L. de; Valentini, Antoninho

    2010-01-01

    Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Moessbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Moessbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.

  4. Iron specificity of a biosensor based on fluorescent pyoverdin immobilized in sol-gel glass

    Science.gov (United States)

    2011-01-01

    Two current technologies used in biosensor development are very promising: 1. The sol-gel process of making microporous glass at room temperature, and 2. Using a fluorescent compound that undergoes fluorescence quenching in response to a specific analyte. These technologies have been combined to produce an iron biosensor. To optimize the iron (II or III) specificity of an iron biosensor, pyoverdin (a fluorescent siderophore produced by Pseudomonas spp.) was immobilized in 3 formulations of porous sol-gel glass. The formulations, A, B, and C, varied in the amount of water added, resulting in respective R values (molar ratio of water:silicon) of 5.6, 8.2, and 10.8. Pyoverdin-doped sol-gel pellets were placed in a flow cell in a fluorometer and the fluorescence quenching was measured as pellets were exposed to 0.28 - 0.56 mM iron (II or III). After 10 minutes of exposure to iron, ferrous ion caused a small fluorescence quenching (89 - 97% of the initial fluorescence, over the range of iron tested) while ferric ion caused much greater quenching (65 - 88%). The most specific and linear response was observed for pyoverdin immobilized in sol-gel C. In contrast, a solution of pyoverdin (3.0 μM) exposed to iron (II or III) for 10 minutes showed an increase in fluorescence (101 - 114%) at low ferrous concentrations (0.45 - 2.18 μM) while exposure to all ferric ion concentrations (0.45 - 3.03 μM) caused quenching. In summary, the iron specificity of pyoverdin was improved by immobilizing it in sol-gel glass C. PMID:21554740

  5. Anisotropic energy-gaps of iron-based superconductivity from intra-band quasiparticle interference in LiFeAs

    Energy Technology Data Exchange (ETDEWEB)

    Rost, A.W. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); Allan, M.P. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Mackenzie, A.P. [SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); Xie, Y. [CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Davis, J.C. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Kavli Institute at Cornell for Nanoscale Science, Cornell, Ithaca, NY 14853 (United States); Kihou, K.; Lee, C.H.; Iyo, A.; Eisaki, H. [AIST, Tsukuba, Ibaraki 305-8568 (Japan); Chuang, T.M. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Inst. of Physics, Academica Sinica, Nankang, Taipei 11529, Taiwan (China)

    2012-07-01

    Cooper pairing in the Fe-based superconductors is thought to occur due to the projection of the antiferromagnetic interactions between iron atoms onto the complex momentum-space electronic structure. A key consequence is that distinct anisotropic energy gaps {Delta}{sub i}(k) with specific relative orientations should occur on the different electronic bands i. To determine this previously unresolved gap structure high-precision spectroscopy is required. Here we introduce the STM technique of intra-band Bogolyubov quasiparticle scattering interference (QPI) to iron-based superconductor studies, focusing on LiFeAs. We identify the QPI signatures of three hole-like dispersions and, by introducing a new QPI technique, determine the magnitude and relative orientations of corresponding anisotropic {Delta}{sub i}(k). Intra-band Bogolyubov QPI therefore yields the spectroscopic information required to identify the mechanism of superconductivity in Fe-based superconductors.

  6. Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

    Directory of Open Access Journals (Sweden)

    S. Costabel

    2018-03-01

    Full Text Available The capability of nuclear magnetic resonance (NMR relaxometry to characterise hydraulic properties of iron-oxide-coated sand and gravel was evaluated in a laboratory study. Past studies have shown that the presence of paramagnetic iron oxides and large pores in coarse sand and gravel disturbs the otherwise linear relationship between relaxation time and pore size. Consequently, the commonly applied empirical approaches fail when deriving hydraulic quantities from NMR parameters. Recent research demonstrates that higher relaxation modes must be taken into account to relate the size of a large pore to its NMR relaxation behaviour in the presence of significant paramagnetic impurities at its pore wall. We performed NMR relaxation experiments with water-saturated natural and reworked sands and gravels, coated with natural and synthetic ferric oxides (goethite, ferrihydrite, and show that the impact of the higher relaxation modes increases significantly with increasing iron content. Since the investigated materials exhibit narrow pore size distributions, and can thus be described by a virtual bundle of capillaries with identical apparent pore radius, recently presented inversion approaches allow for estimation of a unique solution yielding the apparent capillary radius from the NMR data. We found the NMR-based apparent radii to correspond well to the effective hydraulic radii estimated from the grain size distributions of the samples for the entire range of observed iron contents. Consequently, they can be used to estimate the hydraulic conductivity using the well-known Kozeny–Carman equation without any calibration that is otherwise necessary when predicting hydraulic conductivities from NMR data. Our future research will focus on the development of relaxation time models that consider pore size distributions. Furthermore, we plan to establish a measurement system based on borehole NMR for localising iron clogging and controlling its remediation

  7. Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

    Science.gov (United States)

    Costabel, Stephan; Weidner, Christoph; Müller-Petke, Mike; Houben, Georg

    2018-03-01

    The capability of nuclear magnetic resonance (NMR) relaxometry to characterise hydraulic properties of iron-oxide-coated sand and gravel was evaluated in a laboratory study. Past studies have shown that the presence of paramagnetic iron oxides and large pores in coarse sand and gravel disturbs the otherwise linear relationship between relaxation time and pore size. Consequently, the commonly applied empirical approaches fail when deriving hydraulic quantities from NMR parameters. Recent research demonstrates that higher relaxation modes must be taken into account to relate the size of a large pore to its NMR relaxation behaviour in the presence of significant paramagnetic impurities at its pore wall. We performed NMR relaxation experiments with water-saturated natural and reworked sands and gravels, coated with natural and synthetic ferric oxides (goethite, ferrihydrite), and show that the impact of the higher relaxation modes increases significantly with increasing iron content. Since the investigated materials exhibit narrow pore size distributions, and can thus be described by a virtual bundle of capillaries with identical apparent pore radius, recently presented inversion approaches allow for estimation of a unique solution yielding the apparent capillary radius from the NMR data. We found the NMR-based apparent radii to correspond well to the effective hydraulic radii estimated from the grain size distributions of the samples for the entire range of observed iron contents. Consequently, they can be used to estimate the hydraulic conductivity using the well-known Kozeny-Carman equation without any calibration that is otherwise necessary when predicting hydraulic conductivities from NMR data. Our future research will focus on the development of relaxation time models that consider pore size distributions. Furthermore, we plan to establish a measurement system based on borehole NMR for localising iron clogging and controlling its remediation in the gravel pack of

  8. Subsurface iron and arsenic removal: Low-cost technology for community-based water supply in Bangladesh

    KAUST Repository

    Van Halem, Doris; Heijman, Bas G J; Johnston, Richard Bart; Huq, Imamul M.; Ghosh, Sanchari K.; Verberk, Jasper Q J C; Amy, Gary L.; Van Dijk, Johannis C.

    2010-01-01

    The principle of subsurface or in situ iron and arsenic removal is that aerated water is periodically injected into an anoxic aquifer through a tube well, displacing groundwater containing Fe(II). An oxidation zone is created around the tube well where Fe(II) is oxidised. The freshly formed iron hydroxide surfaces provide new sorption sites for soluble Fe(II) andarsenic. The system's efficiency is determined based on the ratio between abstracted volume with reduced iron/arsenic concentrations (V) and the injected volume (Vi). In the field studypresented in this paper, the small-scale application of this technology was investigated in rural Bangladesh. It was found that at small injection volumes (>1m3) iron removal was successful and became more effective with every successive cycle. For arsenic, however, the system did not prove to be very effective yet. Arsenic retardation was only limited and breakthrough of 10mg/L (WHO guideline) was observed before V/Vi = 1, which corresponds to arrival of groundwater at the well. Possible explanations for insufficient arsenic adsorption are the short contact times within the oxidation zone, and the presence of competing anions, like phosphate. © IWA Publishing 2010.

  9. Subsurface iron and arsenic removal: Low-cost technology for community-based water supply in Bangladesh

    KAUST Repository

    Van Halem, Doris

    2010-12-01

    The principle of subsurface or in situ iron and arsenic removal is that aerated water is periodically injected into an anoxic aquifer through a tube well, displacing groundwater containing Fe(II). An oxidation zone is created around the tube well where Fe(II) is oxidised. The freshly formed iron hydroxide surfaces provide new sorption sites for soluble Fe(II) andarsenic. The system\\'s efficiency is determined based on the ratio between abstracted volume with reduced iron/arsenic concentrations (V) and the injected volume (Vi). In the field studypresented in this paper, the small-scale application of this technology was investigated in rural Bangladesh. It was found that at small injection volumes (>1m3) iron removal was successful and became more effective with every successive cycle. For arsenic, however, the system did not prove to be very effective yet. Arsenic retardation was only limited and breakthrough of 10mg/L (WHO guideline) was observed before V/Vi = 1, which corresponds to arrival of groundwater at the well. Possible explanations for insufficient arsenic adsorption are the short contact times within the oxidation zone, and the presence of competing anions, like phosphate. © IWA Publishing 2010.

  10. Fermi surface deformation in a simple iron-based superconductor, FeSe

    Science.gov (United States)

    Coldea, Amalia; Watson, Matthew; Kim, Timur; Haghighirad, Amir; McCollam, Alix; Hoesch, Moritz; Schofield, Andrew

    2015-03-01

    One of the outstanding problems in the field superconductivity is the identification of the normal state out of which superconductivity emerges. FeSe is one of the simplest and most intriguing iron-based superconductors, since in its bulk form it undergoes a structural transition before it becomes superconducting, whereas its single-layer form is believed to be a high-temperature superconductor. The nature of the structural transition, occurring in the absence of static magnetism, is rather unusual and how the electronic structure is stabilized by breaking of the rotational symmetry is the key to understand the superconductivity in bulk FeSe. Here we report angle-resolved photoemission spectroscopy measurements on FeSe that gives direct access to the band structure and orbital-dependent effects. We complement our studies on bulk FeSe with low-temperature angular-dependent quantum oscillation measurements using applied magnetic fields that are sufficiently strong to suppress superconductivity and reach the normal state. These studies reveal a strong deformation of Fermi surface through the structural transition driven by electronic correlations and orbital-dependent effects. . This work was supported by EPSRC, UK (EP/I004475/1), Diamond Light Source, UK and HFML, Nijmegen.

  11. Magnetorheological fluids based on a hyperbranched polycarbosilane matrix and iron microparticles

    International Nuclear Information System (INIS)

    Vasiliev, V G; Buzin, M I; Papkov, V S; Muzafarov, A M; Kramarenko, E Yu; Sheremetyeva, N A; Turenko, D V; Klepikov, I A; Razumovskaya, I V

    2016-01-01

    Magnetorheological fluids (MFs) based on hyperbranched polycarbosilanes as a carrier medium and micron-sized carbonyl iron particles as filler have been synthesized for the first time. Their magnetorheological (MR) behavior has been studied in steady-state flow regime and under dynamic torsion oscillations on a commercial rheometer. At zero magnetic field, in spite of a rather high molecular mass, the hyperbranched polymers as well as their magnetic compositions with up to 72 mass% of magnetic filler demonstrate Newtonian behavior, and their viscosity considerably increases with magnetic filler content. In magnetic fields MFs show a huge MR response. Namely, in steady-state flow experiments a five orders of magnitude increase in viscosity was observed accompanied by magnetic-field-induced well-pronounced non-Newtonian behavior and a non-zero yield stress. Dynamic experiments demonstrate the transition from liquid-like to solid-like behavior of MFs with a large increase in both the storage and loss moduli under application of a magnetic field. In magnetic fields, the rheological behavior of the obtained MF resembles that of soft MR elastomers being mainly determined by the magnetic particle network formed due to magnetic interactions. In particular, like MR elastomers the MFs exhibit the Payne effect, i.e. dependence of the dynamic modulus on the strain amplitude. (paper)

  12. Soil-based screening for iron toxicity tolerance in rice using pots

    Directory of Open Access Journals (Sweden)

    Mouritala Sikirou

    2016-10-01

    Full Text Available The objective of this study was to assess the reliability of pot-based screening method for iron (Fe toxicity tolerance in rice using soils from hot spots. Five lowland rice varieties with known reaction to Fe toxicity were grown in pots in a screen house for three seasons. Fe-toxic soils from two hot spot fields – Edozighi, Nigeria and Niaouli, Benin were used and soil from Africa Rice Center (AfricaRice experimental farm, Cotonou, Benin was included as control. Leaf bronzing score (LBS was determined at different stages, and grain yield was determined at maturity. Heritability was estimated using data across the three seasons. High heritability was recorded for LBS and grain yield. Grain yield reduction in stress treatment relative to control varied from 15 to 56% depending on the variety and soil. Bao Thai, Suakoko 8, and WITA 4 had better performance under Fe toxicity in terms of LBS, yield and relative yield reduction, whereas Bouake 189 and IR64 had poorer performance. Grain yield and LBS were significantly correlated but negatively at 60 days after sowing (DAS. Overall, the results found in this experiment were consistent with previous field studies. Therefore, pot screening using soils from hot spots can be used by rice breeding programs to reliably assess Fe toxicity tolerance ex situ.

  13. Iron Oxide and Gold Based Magneto-Plasmonic Nanostructures for Medical Applications: A Review

    Directory of Open Access Journals (Sweden)

    Thi Thuy Nguyen

    2018-03-01

    Full Text Available Iron oxide and gold-based magneto-plasmonic nanostructures exhibit remarkable optical and superparamagnetic properties originating from their two different components. As a consequence, they have improved and broadened the application potential of nanomaterials in medicine. They can be used as multifunctional nanoprobes for magneto-plasmonic heating as well as for magnetic and optical imaging. They can also be used for magnetically assisted optical biosensing, to detect extreme traces of targeted bioanalytes. This review introduces the previous work on magneto-plasmonic hetero-nanostructures including: (i their synthesis from simple “one-step” to complex “multi-step” routes, including seed-mediated and non-seed-mediated methods; and (ii the characterization of their multifunctional features, with a special emphasis on the relationships between their synthesis conditions, their structures and their properties. It also focuses on the most important progress made with regard to their use in nanomedicine, keeping in mind the same aim, the correlation between their morphology—namely spherical and non-spherical, core-satellite and core-shell, and the desired applications.

  14. Risk based service life prediction of underground cast iron pipes subjected to corrosion

    International Nuclear Information System (INIS)

    Li, C.Q.; Mahmoodian, M.

    2013-01-01

    Aging and deterioration of underground cast iron pipes is inevitable after their long time in service, with corrosion being the most predominant mechanism for pipe failures. Although considerable research has been undertaken in the past few decades, more is on the effects of corrosion on structural capacity of pipes than that on the prediction of their service life. This paper presents a methodology to quantitatively assess the risk of pipe collapse and predict its remaining service life using a time-dependent reliability theory. The concept of stress intensity in fracture mechanics is employed to establish the failure criterion of pipe collapse. An empirical model is derived for maximum pit growth of corrosion from the available data based on mathematical regressions. An example is provided to illustrate the application of the proposed method. It is found in the paper that the risk of pipe collapse increases with an increase in the diameter of the pipe for both external and internal corrosion. It is also found that the tougher the pipe is, the smaller the risk of its collapse. The paper concludes that a time-dependent reliability method is a very useful tool to predict the risk of pipe collapse and its remaining service life. The proposed method can help the water industry develop rehabilitation or replacement strategy for existing pipe networks with a view for better management of the pipe asset

  15. Preliminary neutronic assessment for ATF (Accident Tolerant Fuel) based on iron alloy

    International Nuclear Information System (INIS)

    Abe, Alfredo; Carluccio, Thiago; Piovezan, Pamela; Giovedi, Claudia; Martins, Marcelo R.

    2015-01-01

    After Fukushima Daiichi nuclear accident in 2011, the nuclear fuel performance under accident condition became a very important issue and currently different research and development program are in progress toward to reliability and withstand under accident condition. These initiatives are known as ATF (Accident Tolerant Fuel) R and D program, which many countries with different research institutes, fuel vendors and others are nowadays involved. Accident Tolerant Fuel (ATF) can be defined as enhanced fuel which can tolerate loss of active cooling system capability for a considerably longer time period and the fuel/cladding system can be maintained without significant degradation and can also improve the fuel performance during normal operations and transients, as well as design-basis accident (DBA) and beyond design-basis (BDBA) accident. Different materials have being proposed as fuel cladding candidates considering thermo-mechanical properties and lower reaction kinetic with steam and slower hydrogen production. The aim of this work is to perform a neutronic assessment for several cladding candidates based on iron alloy considering a standard PWR fuel rod (fuel pellet and dimension). The purpose of the assessment is to address different parameters that might contribute for possible neutronic reactivity gain in order to overcome the penalty due to increase of neutron absorption in the cladding materials. All the neutronic assessment is performed using MCNP, Monte Carlo code. (author)

  16. Role of the orbital degree of freedom in iron-based superconductors

    Science.gov (United States)

    Yi, Ming; Zhang, Yan; Shen, Zhi-Xun; Lu, Donghui

    2017-10-01

    Almost a decade has passed since the serendipitous discovery of the iron-based high temperature superconductors (FeSCs) in 2008. The fact that, as in the copper oxide high temperature superconductors, long-range antiferromagnetism in the FeSCs arises in proximity to superconductivity immediately raised the question of the degree of similarity between the two. Despite the great resemblance in their phase diagrams, there exist important differences between the FeSCs and the cuprates that need to be considered in order to paint a full picture of these two families of high temperature superconductors. One of the key differences is the multi-orbital multi-band nature of the FeSCs, which contrasts with the effective single-band nature of the cuprates. Systematic studies of orbital related phenomena in FeSCs have been largely lacking. In this review, we summarize angle-resolved photoemission spectroscopy (ARPES) measurements across various FeSC families that have been reported in literature, focusing on the systematic trends of orbital dependent electron correlations and the role of different Fe 3d orbitals in driving the nematic transition, the spin-density-wave transition, and superconductivity.

  17. High temperature cathodic charging of hydrogen in zirconium alloys and iron and nickel base alloys

    International Nuclear Information System (INIS)

    John, J.T.; De, P.K.; Gadiyar, H.S.

    1990-01-01

    These investigations lead to the development of a new technique for charging hydrogen into metals and alloys. In this technique a mixture of sulfates and bisulfates of sodium and potassium is kept saturated with water at 250-300degC in an open pyrex glass beaker and electrolysed using platinum anode and the material to be charged as the cathode. Most of the studies were carried out on Zr alloys. It is shown that because of the high hydrogen flux available at the surface and the high diffusivity of hydrogen in metals at these temperatures the materials pick up hydrogen faster and more uniformly than the conventional electrolytic charging at room temperature and high temperature autoclaving in LiOH solutions. Chemical analysis, metallographic examination and XRD studies confirm this. This technique has been used to charge hydrogen into many iron and nickel base austentic alloys, which are very resistant to hydrogen pick up and to H-embrittlement. Since this involved a novel method of electrolysing water, the hydrogen/deuterium isotopic ratio has been studied. At this temperatures the D/H ratio in the evolved hydrogen gas was found to be closer to the value in the liquid water, which means a smaller separation factor. This confirm the earlier observation that separation factor decreases with increase of temperature. (author). 16 refs., 21 fi gs., 6 tabs

  18. Effect of iron salt type and dosing mode on Fenton-based pretreatment of rice straw for enzymatic hydrolysis.

    Science.gov (United States)

    Gan, Yu-Yan; Zhou, Si-Li; Dai, Xiao; Wu, Han; Xiong, Zi-Yao; Qin, Yuan-Hang; Ma, Jiayu; Yang, Li; Wu, Zai-Kun; Wang, Tie-Lin; Wang, Wei-Guo; Wang, Cun-Wen

    2018-06-15

    Fenton-based processes with four different iron salts in two different dosing modes were used to pretreat rice straw (RS) samples to increase their enzymatic digestibility. The composition analysis shows that the RS sample pretreated by the dosing mode of iron salt adding into H 2 O 2 has a much lower hemicellulose content than that pretreated by the dosing mode of H 2 O 2 adding into iron salt, and the RS sample pretreated by the chloride salt-based Fenton process has a much lower lignin content and a slightly lower hemicellulose content than that pretreated by the sulphate salt-based Fenton process. The higher concentration of reducing sugar observed on the RS sample with lower lignin and hemicellulose contents justifies that the Fenton-based process could enhance the enzymic hydrolysis of RS by removing hemicellulose and lignin and increasing its accessibility to cellulase. FeCl 3 ·6H 2 O adding into H 2 O 2 is the most efficient Fenton-based process for RS pretreatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. EFFECTIVENESS OF USING DILUTE OXALIC ACID TO DISSOLVE HIGH LEVEL WASTE IRON BASED SLUDGE SIMULANT

    International Nuclear Information System (INIS)

    Ketusky, E

    2008-01-01

    At the Savannah River Site (SRS), near Aiken South Carolina, there is a crucial need to remove residual quantities of highly radioactive iron-based sludge from large select underground storage tanks (e.g., 19,000 liters of sludge per tank), in order to support tank closure. The use of oxalic acid is planned to dissolve the residual sludge, hence, helping in the removal. Based on rigorous testing, primarily using 4 and 8 wt% oxalic acid solutions, it was concluded that the more concentrated the acid, the greater the amount of residual sludge that would be dissolved; hence, a baseline technology on using 8 wt% oxalic acid was developed. In stark contrast to the baseline technology, reports from other industries suggest that the dissolution will most effectively occur at 1 wt% oxalic acid (i.e., maintaining the pH near 2). The driver for using less oxalic acid is that less (i.e., moles) would decrease the severity of the downstream impacts (i.e., required oxalate solids removal efforts). To determine the initial feasibility of using 1 wt% acid to dissolve > 90% of the sludge solids, about 19,000 liters of representative sludge was modeled using about 530,000 liters of 0 to 8 wt% oxalic acid solutions. With the chemical thermodynamic equilibrium based software results showing that 1 wt% oxalic acid could theoretically work, simulant dissolution testing was initiated. For the dissolution testing, existing simulant was obtained, and an approximate 20 liter test rig was built. Multiple batch dissolutions of both wet and air-dried simulant were performed. Overall, the testing showed that dilute oxalic acid dissolved a greater fraction of the stimulant and resulted in a significantly larger acid effectiveness (i.e., grams of sludge dissolved/mole of acid) than the baseline technology. With the potential effectiveness confirmed via simulant testing, additional testing, including radioactive sludge testing, is planned

  20. Nanobiocomposite platform based on polyaniline-iron oxide-carbon nanotubes for bacterial detection.

    Science.gov (United States)

    Singh, Renu; Verma, Rachna; Sumana, G; Srivastava, Avanish Kumar; Sood, Seema; Gupta, Rajinder K; Malhotra, B D

    2012-08-01

    The nanocomposite based on polyaniline (PANI)-iron oxide nanoparticles (nFe(3)O(4)) and multi walled carbon-nanotubes (CNT) has been fabricated onto indium tin oxide (ITO) coated glass plate via facile electrochemical synthesis of polyaniline in presence of nFe(3)O(4) (~20 nm) and CNT (20-80 nm in diameter). The results of transmission electron microscopic studies show evidence of coating of PANI and nFe(3)O(4) onto the CNT. The PANI-nFe(3)O(4)-CNT/ITO nanoelectrode has been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy studies. The biotinylated nucleic acid probe sequence consisting of 20 bases has been immobilized onto PANI-nFe(3)O(4)-CNT/ITO nanoelectrode using biotin-avidin coupling. It is shown that the PANI-nFe(3)O(4)-CNT platform based biosensor can be used to specifically detect bacteria (N. gonorrhoeae) at minute concentration as low as (1×10(-19) M) indicating high sensitivity within 45 s of hybridization time at 298 K by differential pulse voltammetry using methylene blue as electroactive indicator. This bacterial sensor has also been tested with 4 positive and 4 negative PCR amplicons of gonorrhoea affected patient samples. The results of these studies have implications towards the fabrication of a handheld device for Neisseria gonorrhoeae detection that may perhaps result in a decrease in the human immunodeficiency virus infections. Copyright © 2012 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2010-10-04

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

  2. Sub-core permeability and relative permeability characterization with Positron Emission Tomography

    Science.gov (United States)

    Zahasky, C.; Benson, S. M.

    2017-12-01

    This study utilizes preclinical micro-Positron Emission Tomography (PET) to image and quantify the transport behavior of pulses of a conservative aqueous radiotracer injected during single and multiphase flow experiments in a Berea sandstone core with axial parallel bedding heterogeneity. The core is discretized into streamtubes, and using the micro-PET data, expressions are derived from spatial moment analysis for calculating sub-core scale tracer flux and pore water velocity. Using the flux and velocity data, it is then possible to calculate porosity and saturation from volumetric flux balance, and calculate permeability and water relative permeability from Darcy's law. Full 3D simulations are then constructed based on this core characterization. Simulation results are compared with experimental results in order to test the assumptions of the simple streamtube model. Errors and limitations of this analysis will be discussed. These new methods of imaging and sub-core permeability and relative permeability measurements enable experimental quantification of transport behavior across scales.

  3. Permeability measuremens of brazilian Eucalyptus

    Directory of Open Access Journals (Sweden)

    Marcio Rogério da Silva

    2010-09-01

    Full Text Available The permeability of Brazilian Eucalyptus grandis and Eucalyptus citriodora wood was measured in a custom build gas analysis chamber in order to determine which species could be successfully treated with preservatives. Liquid permeability was tested using an emulsion of Neen oil and a control of distillated water. Air was used to test the gas phase permeability. For both Eucalyptus grandis and Eucalyptus citriodora, the longitudinal permeability of gas was shown to be about twice as great as the liquid phase permeability. No radial permeability was observed for either wood. The permeability of air and water through the sapwood of Eucalyptus grandis was greater than that through the sapwood of Eucalyptus citriodora. The permeability of neen oil preservative through the sapwood of Eucalyptus grandis was also greater than through the sapwood of E. Citradora, but the difference was not statistically significant. Scanning Electron Microscopy images showed that the distribution and obstruction in the vessels could be correlated with observed permeability properties. Irrespective of the causes of differences in permeability between the species, the fluid phase flux through the sapwood of both species was significant, indicating that both Eucalyptus grandis and Eucalyptus citriodora could be successfully treated with wood preservative.

  4. Fast Laplace solver approach to pore-scale permeability

    Science.gov (United States)

    Arns, C. H.; Adler, P. M.

    2018-02-01

    We introduce a powerful and easily implemented method to calculate the permeability of porous media at the pore scale using an approximation based on the Poiseulle equation to calculate permeability to fluid flow with a Laplace solver. The method consists of calculating the Euclidean distance map of the fluid phase to assign local conductivities and lends itself naturally to the treatment of multiscale problems. We compare with analytical solutions as well as experimental measurements and lattice Boltzmann calculations of permeability for Fontainebleau sandstone. The solver is significantly more stable than the lattice Boltzmann approach, uses less memory, and is significantly faster. Permeabilities are in excellent agreement over a wide range of porosities.

  5. Effect of desensitizing agents on dentin permeability.

    Science.gov (United States)

    Ishihata, Hiroshi; Kanehira, Masafumi; Nagai, Tomoko; Finger, Werner J; Shimauchi, Hidetoshi; Komatsu, Masashi

    2009-06-01

    To investigate the in vitro efficacy of two dentin desensitizing products at reducing liquid permeability through human dentin discs. The tested hypothesis was that the products, in spite of different chemical mechanisms were not different at reducing or eliminating flow through dentin discs. Dentin slices (1 mm thick) were prepared from 16 extracted human third molars and their permeability was indirectly recorded in a split chamber model, using a chemiluminescence technique, after EDTA treatment (control), after soaking with albumin, and after desensitizer application. Two products were studied: MS Coat, a self-curing resin-containing oxalate product, and Gluma Desensitizer, a glutaraldehyde/HEMA-based agent without initiator. The dentin slices were mounted between an upper chamber, filled with an aqueous solution of 1% potassium ferricyanide and 0.3% hydrogen peroxide, and a lower chamber filled with 1% sodium hydroxide solution and 0.02% luminol. The upper solution was pressurized, and upon contact with the luminol solution a photochemical signal was generated and recorded as a measure of permeability throughout two consecutive pressurizing cycles at 2.5 and 13 kPa (26 and 133 cm H2O), respectively. The permeability of the control and albumin-soaked samples was similarly high. After application of the desensitizing agents, dentin permeability was reduced to virtually zero at both pressure levels (P < 0.001).

  6. Microstructural development and mechanical properties of iron based cermets processed by pressureless and spark plasma sintering

    International Nuclear Information System (INIS)

    Alvaredo, P.; Gordo, E.; Van der Biest, O.; Vanmeensel, K.

    2012-01-01

    Highlights: ► Processing of Fe-based cermets by pressureless sintering and spark plasma sintering. ► Influence of carbon content on the sintering mechanism and hardness. ► The cermet phase diagram was calculated and permits to explain the microstructure. ► SPS provides ferritic matrix and different carbide distribution than CPS samples. ► Pressureless sintered samples contain retained austenite at room temperature. - Abstract: Iron-based cermets are an interesting class of metal-ceramic composites in which properties and the factors influencing them are to be explored. In this work the metal matrix contains Cr, W, Mo and V as alloying elements, and the hard phase is constituted by 50 vol% of titanium carbonitride (TiCN) particles. The work studies the influence of the C content and the processing method on the sinterability, microstructure and hardness of the developed cermet materials. For that purpose, cermet samples with different C content in the matrix (0 wt%, 0.25 wt%, 0.5 wt%, 1.0 wt%) were prepared by conventional pressureless sintering (CPS) and, in order to achieve finer microstructures and to reduce the sintering time, by spark plasma sintering (SPS). The density and hardness (HV30) of the processed materials was evaluated, while their phase composition and microstructure was characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The equilibrium phase diagram of the composite material was calculated by ThermoCalc software in order to elucidate the influence of the carbon content on the obtained phases and developed microstructures.

  7. Development of an abiraterone acetate formulation with improved oral bioavailability guided by absorption modeling based on in vitro dissolution and permeability measurements.

    Science.gov (United States)

    Solymosi, Tamás; Ötvös, Zsolt; Angi, Réka; Ordasi, Betti; Jordán, Tamás; Semsey, Sándor; Molnár, László; Ránky, Soma; Filipcsei, Genovéva; Heltovics, Gábor; Glavinas, Hristos

    2017-10-30

    Particle size reduction of drug crystals in the presence of surfactants (often called "top-down" production methods) is a standard approach used in the pharmaceutical industry to improve bioavailability of poorly soluble drugs. Based on the mathematical model used to predict the fraction dose absorbed this formulation approach is successful when dissolution rate is the main rate limiting factor of oral absorption. In case compound solubility is also a major factor this approach might not result in an adequate improvement in bioavailability. Abiraterone acetate is poorly water soluble which is believed to be responsible for its very low bioavailability in the fasted state and its significant positive food effect. In this work, we have successfully used in vitro dissolution, solubility and permeability measurements in biorelevant media to describe the dissolution characteristics of different abiraterone acetate formulations. Mathematical modeling of fraction dose absorbed indicated that reducing the particle size of the drug cannot be expected to result in significant improvement in bioavailability in the fasted state. In the fed state, the same formulation approach can result in a nearly complete absorption of the dose; thereby, further increasing the food effect. Using a "bottom-up" formulation method we improved both the dissolution rate and the apparent solubility of the compound. In beagle dog studies, this resulted in a ≫>10-fold increase in bioavailability in the fasted state when compared to the marketed drug and the elimination of the food effect. Calculated values of fraction dose absorbed were in agreement with the observed relative bioavailability values in beagle dogs. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The kinetics of phase transformations of undercooled austenite of the Mn-Ni iron based model alloy

    OpenAIRE

    E. Rożniata; R. Dziurka; J. Pacyna

    2011-01-01

    Purpose: Present work corresponds to the research on the kinetics of phase transformations of undercooled austenite of Mn-Ni iron based model alloy. The kinetics of phase transformations of undercooled austenite of investigated alloy was presented on CCT diagram (continuous cooling transformation). Also the methodology of a dilatometric samples preparation and the method of the critical points determination were described.Design/methodology/approach: The austenitising temperature was defined ...

  9. Innovative design of ironing board based on Kansei Engineering and usability test

    Directory of Open Access Journals (Sweden)

    Zhafira Nadia

    2018-01-01

    Full Text Available Laundry business is popular service business in Indonesia that mostly involve muscle activity for lifting and ironing activity. It causes the worker get muscular fatigue and injury especially for ironing activity that is included in the static and monotonous activity. moreover, existed ironing board design in the market is not easy to be adjusted to standing or sitting position of workers. Hence, this paper aimed to design the innovative and adjustable ironing board to minimize the musculoskeletal complaint. The preliminary study is conducted by NBM questionnaires found that fatigue experienced mostly in the back, right upper arm, and calves. The product designed by Kansei engineering to satisfy consumer's feeling and assessed by USE questionnaire to fulfil consumer's usability. Orthogonal array and conjoint analysis were conducted to incorporate all attribute potentials in developing a new single concept design. Statistical analysis was also done to test the hypothesis. 80 respondents have participated in this study. The result of this study is an innovative design of ironing board which is valid to meet consumers' needs such as comfort, secure, attractive, sturdy, durable and multifunction and practical at 5% of the significant level.

  10. Effect of single interstitial impurity in iron-based superconductors with sign-changed s-wave pairing symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiang-Long, E-mail: xlyu@theory.issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Liu, Da-Yong; Quan, Ya-Min; Zheng, Xiao-Jun [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Zou, Liang-Jian, E-mail: zou@theory.issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Department of Physics, University of Science and Technology of China, Hefei 230026 (China)

    2015-12-15

    Highlights: • Effects of single interstitial impurity are studied in iron-based superconductors. • Bound states within the superconducting gap can be induced. • The interstitial impurity can induce a π phase shift of pairing order parameter. • For strong magnetic scattering the bound-state peak can appear at the Fermi level. - Abstract: We employ the self-consistent Bogoliubov-de Gennes (BdG) formulation to investigate the effect of single interstitial nonmagnetic/magnetic impurity in iron-based superconductors with s ± -wave pairing symmetry. We find that both the nonmagnetic and magnetic impurities can induce bound states within the superconducting (SC) gap and a π phase shift of SC order parameter at the impurity site. However, different from the interstitial-nonmagnetic-impurity case characterized by two symmetric peaks with respect to zero energy, the interstitial magnetic one only induces single bound-state peak. In the strong scattering regime this peak can appear at the Fermi level, which has been observed in the recent scanning tunneling microscope (STM) experiment of Fe(Te,Se) superconductor with interstitial Fe impurities (Yin et al. 2015 [44]). This novel single in-gap peak feature also distinguishes the interstitial case from the substitutional one with two peaks. These results provide important information for comparing the different impurity effects in the iron-based superconductors.

  11. The impact of in-situ stress and outcrop-based fracture geometry on hydraulic aperture and upscaled permeability in fractured reservoirs

    DEFF Research Database (Denmark)

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamid

    2016-01-01

    explicitly, we quantify equivalent permeability, i.e. combined matrix and stress-dependent fracture flow. Fracture networks extracted from a large outcropping pavement form the basis of these models. The results show that the angle between fracture strike and σ 1 has a controlling impact on aperture...

  12. Towards the rational design of novel drugs based on solubility, partitioning/distribution, biomimetic permeability and biological activity exemplified by 1,2,4-thiadiazole derivatives

    DEFF Research Database (Denmark)

    Volkova, T. V.; Terekhova, I. V.; Silyukov, O. I.

    2017-01-01

    -octanol/buffer (pH 7.4) and 1-hexane/buffer (pH 7.4) immiscible phases as model systems imitating the gastrointestinal tract epithelium and the blood-brain barrier were determined. Permeation experiments the new Permeapad™ barrier using Franz diffusion cells were conducted and the apparent permeability...

  13. Low temperature irradiation effects on iron-boron based amorphous metallic alloys

    International Nuclear Information System (INIS)

    Audouard, Alain.

    1983-01-01

    Three iron-boron amorphous alloys and the crystalline Fe 3 B alloy have been irradiated at liquid hydrogen temperature. 2,4 MeV electron irradiation induces the creation of point defects in the amorphous alloys as well as in the crystalline Fe 3 B alloy. These point defects can be assimilated to iron ''Frenkel pairs''. They have been characterized by determining their intrinsic electrical resistivity and their formation volume. The displacement threshold energy of iron atoms has also been determined. 10 B fission fragments induce, in these amorphous alloys, displacement cascades which lead to stable vacancy rich zones. This irradiation also leads to a structural disorder in relation with the presence of defects. 235 U fission fragments irradiation modifies drastically the structure of the amorphous alloys. The results have been interpreted on the basis of the coexistence of two opposite processes which induce local disorder and crystallisation respectively [fr

  14. Polyvinylpyrrolidone and arsenic-induced changes in biological responses of model aquatic organisms exposed to iron-based nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Llaneza, Verónica [University of Florida, Engineering School of Sustainable Infrastructure and Environment, Department of Environmental Engineering Sciences (United States); Rodea-Palomares, Ismael [Univ. Autonoma de Madrid, Dept. de Biologia, Facultad de Ciencias (Spain); Zhou, Zuo [University of Florida, Engineering School of Sustainable Infrastructure and Environment, Department of Environmental Engineering Sciences (United States); Rosal, Roberto [Univ. de Alcalá, Dept. de Ingeniería Química (Spain); Fernández-Pina, Francisca [Univ. Autonoma de Madrid, Dept. de Biologia, Facultad de Ciencias (Spain); Bonzongo, Jean-Claude J., E-mail: bonzongo@ufl.edu [University of Florida, Engineering School of Sustainable Infrastructure and Environment, Department of Environmental Engineering Sciences (United States)

    2016-08-15

    The efficiency of zero-valent iron particles used in the remediation of contaminated groundwater has, with the emergence of nanotechnology, stimulated interest on the use of nano-size particles to take advantage of high-specific surface area and reactivity characteristics of nanoparticles (NPs). Accordingly, engineered iron-NPs are among the most widely used nanomaterials for in situ remediation. However, while several ecotoxicity studies have been conducted to investigate the adverse impacts of these NPs on aquatic organisms, research on the implications of spent iron-based NPs is lacking. In this study, a comparative approach is used, in which the biological effects of three iron-based NPs (Fe{sub 3}O{sub 4} and γ-Fe{sub 2}O{sub 3} NPs with particle sizes ranging from 20 to 50 nm, and Fe{sup 0}-NPs with an average particle size of 40 nm) on Raphidocelis subcapitata (formely known as Pseudokirchneriella subcapitata) and Daphnia magna were investigated using both as-prepared and pollutant-doped Fe-based NPs. For the latter, arsenic (As) was used as example sorbed pollutant. The results show that improved degree of NP dispersion by use of polyvinylpyrrolidone overlapped with both increased arsenic adsorption capacity and toxicity to the tested organisms. For R. subcapitata, Fe-oxide NPs were more toxic than Fe{sup 0}-NPs, due primarily to differences in the degree of NPs aggregation and ability to produce reactive oxygen species. For the invertebrate D. magna, a similar trend of biological responses was observed, except that sorption of As to Fe{sup 0}-NPs significantly increased the toxic response when compared to R. subcapitata. Overall, these findings point to the need for research on downstream implications of NP-pollutant complexes generated during water treatment by injection of NPs into aquatic systems.

  15. Polyvinylpyrrolidone and arsenic-induced changes in biological responses of model aquatic organisms exposed to iron-based nanoparticles

    International Nuclear Information System (INIS)

    Llaneza, Verónica; Rodea-Palomares, Ismael; Zhou, Zuo; Rosal, Roberto; Fernández-Pina, Francisca; Bonzongo, Jean-Claude J.

    2016-01-01

    The efficiency of zero-valent iron particles used in the remediation of contaminated groundwater has, with the emergence of nanotechnology, stimulated interest on the use of nano-size particles to take advantage of high-specific surface area and reactivity characteristics of nanoparticles (NPs). Accordingly, engineered iron-NPs are among the most widely used nanomaterials for in situ remediation. However, while several ecotoxicity studies have been conducted to investigate the adverse impacts of these NPs on aquatic organisms, research on the implications of spent iron-based NPs is lacking. In this study, a comparative approach is used, in which the biological effects of three iron-based NPs (Fe_3O_4 and γ-Fe_2O_3 NPs with particle sizes ranging from 20 to 50 nm, and Fe"0-NPs with an average particle size of 40 nm) on Raphidocelis subcapitata (formely known as Pseudokirchneriella subcapitata) and Daphnia magna were investigated using both as-prepared and pollutant-doped Fe-based NPs. For the latter, arsenic (As) was used as example sorbed pollutant. The results show that improved degree of NP dispersion by use of polyvinylpyrrolidone overlapped with both increased arsenic adsorption capacity and toxicity to the tested organisms. For R. subcapitata, Fe-oxide NPs were more toxic than Fe"0-NPs, due primarily to differences in the degree of NPs aggregation and ability to produce reactive oxygen species. For the invertebrate D. magna, a similar trend of biological responses was observed, except that sorption of As to Fe"0-NPs significantly increased the toxic response when compared to R. subcapitata. Overall, these findings point to the need for research on downstream implications of NP-pollutant complexes generated during water treatment by injection of NPs into aquatic systems.

  16. Polyvinylpyrrolidone and arsenic-induced changes in biological responses of model aquatic organisms exposed to iron-based nanoparticles

    Science.gov (United States)

    Llaneza, Verónica; Rodea-Palomares, Ismael; Zhou, Zuo; Rosal, Roberto; Fernández-Pina, Francisca; Bonzongo, Jean-Claude J.

    2016-08-01

    The efficiency of zero-valent iron particles used in the remediation of contaminated groundwater has, with the emergence of nanotechnology, stimulated interest on the use of nano-size particles to take advantage of high-specific surface area and reactivity characteristics of nanoparticles (NPs). Accordingly, engineered iron-NPs are among the most widely used nanomaterials for in situ remediation. However, while several ecotoxicity studies have been conducted to investigate the adverse impacts of these NPs on aquatic organisms, research on the implications of spent iron-based NPs is lacking. In this study, a comparative approach is used, in which the biological effects of three iron-based NPs (Fe3O4 and γ-Fe2O3 NPs with particle sizes ranging from 20 to 50 nm, and Fe0-NPs with an average particle size of 40 nm) on Raphidocelis subcapitata (formely known as Pseudokirchneriella subcapitata) and Daphnia magna were investigated using both as-prepared and pollutant-doped Fe-based NPs. For the latter, arsenic (As) was used as example sorbed pollutant. The results show that improved degree of NP dispersion by use of polyvinylpyrrolidone overlapped with both increased arsenic adsorption capacity and toxicity to the tested organisms. For R. subcapitata, Fe-oxide NPs were more toxic than Fe0-NPs, due primarily to differences in the degree of NPs aggregation and ability to produce reactive oxygen species. For the invertebrate D. magna, a similar trend of biological responses was observed, except that sorption of As to Fe0-NPs significantly increased the toxic response when compared to R. subcapitata. Overall, these findings point to the need for research on downstream implications of NP-pollutant complexes generated during water treatment by injection of NPs into aquatic systems.

  17. Iron based pnictide and chalcogenide superconductors studied by muon spin spectroscopy

    International Nuclear Information System (INIS)

    Shermadini, Zurab

    2014-01-01

    In the present thesis the superconducting properties of the Iron-based Ba 1-x Rb x Fe 2 As 2 arsenides, and A x Fe 2-y Se 2 (A=Cs,Rb,K) chalcogenides are investigated by means of Muon Spin Rotation Spectroscopy. The temperature and pressure dependence of the magnetic penetration depth is obtained form μSR experiments and analyzed to probe the superconducting gap-symmetries for each samples. The Ba 1-x Rb x Fe 2 As 2 system is described within the multi-gap s+s-wave scenario and results are discussed in the light of the suppression of inter-band processes upon hole doping. Due to the lowered upper critical field B c2 and reduced T c , a large section of B-T-p phase diagram is studied for the hole-overdoped x=1 case. By applying hydrostatic pressure, the RbFe 2 As 2 system exhibits a classical BCS superconducting characteristics. The A x Fe 2-y Se 2 chalcogenide represents a system containing magnetically ordered and superconducting phases simultaneously. In all investigated chalcogenide samples, about 90% of the total volume show the strong antiferromagnetic phase and 10% exhibit a paramagnetic behavior. Magnetization measurements reveal a 100% Meissner effect, while μSR clearly indicates that the paramagnetic phase is a perfect superconductor. Up to now, there is no clear evidence whether the antiferromagnetic phase is also superconducting. The microscopic coexistence and/or phase separation of superconductivity and magnetism is discussed. Moreover, a new hydrostatic double-wall pressure cell is developed and produced, satisfying the demands of μSR experiments. The designs and characteristics of the new pressure cell are reviewed in the present thesis.

  18. Redox switching and oxygen evolution at oxidized metal and metal oxide electrodes: iron in base.

    Science.gov (United States)

    Lyons, Michael E G; Doyle, Richard L; Brandon, Michael P

    2011-12-28

    Outstanding issues regarding the film formation, redox switching characteristics and the oxygen evolution reaction (OER) electrocatalytic behaviour of multicycled iron oxyhydroxide films in aqueous alkaline solution have been revisited. The oxide is grown using a repetitive potential multicycling technique, and the mechanism of the latter hydrous oxide formation process has been discussed. A duplex layer model of the oxide/solution interphase region is proposed. The acid/base behaviour of the hydrous oxide and the microdispersed nature of the latter material has been emphasised. The hydrous oxide is considered as a porous assembly of interlinked octahedrally coordinated anionic metal oxyhydroxide surfaquo complexes which form an open network structure. The latter contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution, and also charge compensating cations. The dynamics of redox switching has been quantified via analysis of the cyclic voltammetry response as a function of potential sweep rate using the Laviron-Aoki electron hopping diffusion model by analogy with redox polymer modified electrodes. Steady state Tafel plot analysis has been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slope values of ca. 60 mV dec(-1) and ca. 120 mV dec(-1) are found at low and high overpotentials respectively, whereas the reaction order with respect to hydroxide ion activity changes from ca. 3/2 to ca. 1 as the potential is increased. These observations are rationalised in terms of a kinetic scheme involving Temkin adsorption and the rate determining formation of a physisorbed hydrogen peroxide intermediate on the oxide surface. The dual Tafel slope behaviour is ascribed to the potential dependence of the surface coverage of adsorbed intermediates.

  19. First-principles investigations of iron-based alloys and their properties

    Science.gov (United States)

    Limmer, Krista Renee

    Fundamental understanding of the complex interactions governing structure-property relationships in iron-based alloys is necessary to advance ferrous metallurgy. Two key components of alloy design are carbide formation and stabilization and controlling the active deformation mechanism. Following a first-principles methodology, understanding on the electronic level of these components has been gained for predictive modeling of alloys. Transition metal carbides have long played an important role in alloy design, though the complexity of their interactions with the ferrous matrix is not well understood. Bulk, surface, and interface properties of vanadium carbide, VCx, were calculated to provide insight for the carbide formation and stability. Carbon vacancy defects are shown to stabilize the bulk carbide due to increased V-V bonding in addition to localized increased V-C bond strength. The VCx (100) surface energy is minimized when carbon vacancies are at least two layers from the surface. Further, the Fe/VC interface is stabilized through maintaining stoichiometry at the Fe/VC interface. Intrinsic and unstable stacking fault energy, gammaisf and gamma usf respectively, were explicitly calculated in nonmagnetic fcc Fe-X systems for X = Al, Si, P, S, and the 3d and 4d transition elements. A parabolic relationship is observed in gamma isf across the transition metals with minimums observed for Mn and Tc in the 3d and 4d periods, respectively. Mn is the only alloying addition that was shown to decrease gamma isf in fcc Fe at the given concentration. The effect of alloying on gammausf also has a parabolic relationship, with all additions decreasing gammaisf yielding maximums for Fe and Rh.

  20. Shock Wave Response of Iron-based In Situ Metallic Glass Matrix Composites.

    Science.gov (United States)

    Khanolkar, Gauri R; Rauls, Michael B; Kelly, James P; Graeve, Olivia A; Hodge, Andrea M; Eliasson, Veronica

    2016-03-02

    The response of amorphous steels to shock wave compression has been explored for the first time. Further, the effect of partial devitrification on the shock response of bulk metallic glasses is examined by conducting experiments on two iron-based in situ metallic glass matrix composites, containing varying amounts of crystalline precipitates, both with initial composition Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4. The samples, designated SAM2X5-600 and SAM2X5-630, are X-ray amorphous and partially crystalline, respectively, due to differences in sintering parameters during sample preparation. Shock response is determined by making velocity measurements using interferometry techniques at the rear free surface of the samples, which have been subjected to impact from a high-velocity projectile launched from a powder gun. Experiments have yielded results indicating a Hugoniot Elastic Limit (HEL) to be 8.58 ± 0.53 GPa for SAM2X5-600 and 11.76 ± 1.26 GPa for SAM2X5-630. The latter HEL result is higher than elastic limits for any BMG reported in the literature thus far. SAM2X5-600 catastrophically loses post-yield strength whereas SAM2X5-630, while showing some strain-softening, retains strength beyond the HEL. The presence of crystallinity within the amorphous matrix is thus seen to significantly aid in strengthening the material as well as preserving material strength beyond yielding.

  1. Computational thermodynamics and genetic algorithms to design affordable γ′-strengthened nickel–iron based superalloys

    International Nuclear Information System (INIS)

    Tancret, F

    2012-01-01

    Computational thermodynamics based on the CALPHAD approach (Thermo-Calc software) are used to design creep-resistant and affordable superalloys for large-scale applications such as power plants. Cost is reduced by the introduction of iron and by avoiding the use of expensive alloying elements such as Nb, Ta, Mo, Co etc. Strengthening is ensured by the addition of W, and of Al and Ti to provoke the precipitation of γ′. However, the addition of iron reduces the maximum possible volume fraction of γ′. The latter is maximized automatically using a genetic algorithm during simulation, while keeping the alloys free of undesirable phases at high temperatures. New superalloys with 20 wt% Cr are designed, with Fe content up to 37 wt%. They should be forgeable, weldable, oxidation resistant and significantly cheaper than existing alloys with equivalent properties. (paper)

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... other conditions that can cause iron-deficiency anemia. Blood tests to screen for iron-deficiency anemia To screen ... check the size of your liver and spleen. Blood tests Based on results from blood tests to screen ...

  3. Microelectrodes Based investigation of the Impacts of Water Chemistry on Copper and Iron Corrosion

    Science.gov (United States)

    The effect of bulk drinking water quality on copper and iron pipe corrosion has been extensively studied. Despite past research, many have argued that bulk water quality does not necessarily reflect water quality near the water-metal interface and that such knowledge is necessary...

  4. In vitro degradation and surface bioactivity of iron-matrix composites containing silicate-based bioceramic

    NARCIS (Netherlands)

    Wang, S; Xu, Y; Zhou, J.; Li, H; Chang, Jiang; Huan, Z

    2017-01-01

    Iron-matrix composites with calcium silicate (CS) bioceramic as the reinforcing phase were fabricated through powder metallurgy processes. The microstructures, mechanical properties, apatite deposition and biodegradation behavior of the Fe-CS composites, as well as cell attachment and proliferation

  5. {Fe6O2}-Based Assembly of a Tetradecanuclear Iron Nanocluster

    Directory of Open Access Journals (Sweden)

    Svetlana G. Baca

    2011-01-01

    Full Text Available The tetradecanuclear FeIII pivalate nanocluster [Fe14O10(OH4(Piv18], comprising a new type of metal oxide framework, has been solvothermally synthesized from a hexanuclear iron pivalate precursor in dichlormethane/acetonitrile solution. Magnetic measurements indicate the presence of very strong antiferromagnetic interactions in the cluster core.

  6. New strategies to prolong the in vivo life span of iron-based contrast agents for MRI.

    Directory of Open Access Journals (Sweden)

    Antonella Antonelli

    Full Text Available Superparamagnetic iron oxide (SPIO and ultra small superparamagnetic iron oxide (USPIO nanoparticles have been developed as magnetic resonance imaging (MRI contrast agents. Iron oxide nanoparticles, that become superparamagnetic if the core particle diameter is ~ 30 nm or less, present R1 and R2 relaxivities which are much higher than those of conventional paramagnetic gadolinium chelates. Generally, these magnetic particles are coated with biocompatible polymers that prevent the agglomeration of the colloidal suspension and improve their blood distribution profile. In spite of their potential as MRI blood contrast agents, the biomedical application of iron oxide nanoparticles is still limited because of their intravascular half-life of only few hours; such nanoparticles are rapidly cleared from the bloodstream by macrophages of the reticulo-endothelial system (RES. To increase the life span of these MRI contrast agents in the bloodstream we proposed the encapsulation of SPIO nanoparticles in red blood cells (RBCs through the transient opening of cell membrane pores. We have recently reported results obtained by applying our loading procedure to several SPIO nanoparticles with different chemical physical characteristics such as size and coating agent. In the current investigation we showed that the life span of iron-based contrast agents in the mice bloodstream was prolonged to 12 days after the intravenous injection of murine SPIO-loaded RBCs. Furthermore, we developed an animal model that implicates the pretreatment of animals with clodronate to induce a transient suppression of tissue macrophages, followed by the injection of human SPIO-loaded RBCs which make it possible to encapsulate nanoparticle concentrations (5.3-16.7 mM Fe higher than murine SPIO-loaded RBCs (1.4-3.55 mM Fe. The data showed that, when human RBCs are used as more capable SPIO nanoparticle containers combined with a depletion of tissue macrophages, Fe concentration in

  7. Facile fabrication of iron-based superhydrophobic surfaces via electric corrosion without bath

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Qinghe [College of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Liu, Hongtao, E-mail: liuht100@126.com [College of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Chen, Tianchi [College of Mechanical & Electrical Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China); Wei, Yan; Wei, Zhu [College of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221116 (China)

    2016-04-30

    carbon steel substrate under appropriate process; the contact angle of the as-prepared superhydrophobic surface can be up to 152 ± 0.5°, and the sliding angle is 1–2°; its anti-corrosion property, anti-icing performance and the friction property all show an excellent level. This method provides the possibility of industrialization of superhydrophobic surface based on iron substrate as it can prepare massive superhydrophobic surface quickly.

  8. Spectrophotometric determination of iron species using a combination of artificial neural networks and dispersive liquid–liquid microextraction based on solidification of floating organic drop

    International Nuclear Information System (INIS)

    Moghadam, Masoud Rohani; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh

    2011-01-01

    Highlights: ► Combination of DLLME-SFO/fiber optic-linear array detection/chemometric methods. ► Simultaneous determination of complexes with overlapping spectra. ► A novel DLLME-SFO method is proposed for extraction of iron species. ► The extracted iron species are simultaneous determined using PC-ANNs. ► The enhancement factor of 162 and 125 are achieved for Fe 3+ and Fe 2+ , respectively. - Abstract: A dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and artificial neural networks method was developed for the simultaneous separation/preconcentration and speciation of iron in water samples. In this method, an appropriate mixture of ethanol (as the disperser solvent) and 1-undecanol (as the extracting solvent) containing appropriate amount of 2-thenoyltrifluoroacetone (TTA) (as the complexing agent) was injected rapidly into the water sample containing iron (II) and iron (III) species. At this step, the iron species interacted with the TTA and extracted into the 1-undecanol. After the phase separation, the absorbance of the extracted irons was measured in the wavelength region of 450–600 nm. The artificial neural networks were then applied for simultaneous determination of individual iron species. Under optimum conditions, the calibration graphs were linear in the range of 95–1070 μg L −1 and 31–350 μg L −1 with detection limits of 25 and 8 μg L −1 for iron (II) and iron (III), respectively. The relative standard deviations (R.S.D., n = 6) were lower than 4.2%. The enhancement factor of 162 and 125 were obtained for Fe 3+ and Fe 2+ ions, respectively. The procedure was applied to power plant drum water and several potable water samples; and accuracy was assessed through the recovery experiments and independent analysis by graphite furnace atomic absorption spectrometry.

  9. Bio-mimicked atomic-layer-deposited iron oxide-based memristor with synaptic potentiation and depression functions

    Science.gov (United States)

    Wan, Xiang; Gao, Fei; Lian, Xiaojuan; Ji, Xincun; Hu, Ertao; He, Lin; Tong, Yi; Guo, Yufeng

    2018-06-01

    In this study, an iron oxide (FeO x )-based memristor was investigated for the realization of artificial synapses. An FeO x resistive switching layer was prepared by self-limiting atomic layer deposition (ALD). The movement of oxygen vacancies enabled the device to have history-dependent synaptic functions, which was further demonstrated by device modeling and simulation. Analog synaptic potentiation/depression in conductance was emulated by applying consecutive voltage pulses in the simulation. Our results suggest that the ALD FeO x -based memristor can be used as the basic building block for neural networks, neuromorphic systems, and brain-inspired computers.

  10. Diffusion of hydrogen in iron oxides

    International Nuclear Information System (INIS)

    Bruzzoni, P.

    1993-01-01

    The diffusion of hydrogen in transitions metals oxides has been recently studied at room temperature through the permeability electrochemical technique. This work studies thin oxide layers grown in air or in presence of oxidizing atmospheres at temperatures up to 200 deg C. The substrate was pure iron with different superficial treatments. It was observed that these oxides reduce up to three magnitudes orders, the hydrogen stationary flux through membranes of usual thickness in comparison with iron membranes free of oxide. (Author)

  11. Electrokinetic effects and fluid permeability

    International Nuclear Information System (INIS)

    Berryman, J.G.

    2003-01-01

    Fluid permeability of porous media depends mainly on connectivity of the pore space and two physical parameters: porosity and a pertinent length-scale parameter. Electrical imaging methods typically establish connectivity and directly measure electrical conductivity, which can then often be related to porosity by Archie's law. When electrical phase measurements are made in addition to the amplitude measurements, information about the pertinent length scale can then be obtained. Since fluid permeability controls the ability to flush unwanted fluid contaminants from the subsurface, inexpensive maps of permeability could improve planning strategies for remediation efforts. Detailed knowledge of fluid permeability is also important for oil field exploitation, where knowledge of permeability distribution in three dimensions is a common requirement for petroleum reservoir simulation and analysis, as well as for estimates on the economics of recovery

  12. Comparison of Tensile, Permeability and Color Properties of Starch-based Bionanocomposites Containing Two Types of Fillers: Sodium Montmorilonite and Cellulose Nanocrystal

    Directory of Open Access Journals (Sweden)

    Nooshin Noushirvani

    2013-01-01

    Full Text Available The objective of this research was to compare the tensile, permeability, solubility and color properties of plasticized starch-polyvinyl alcohol-Montmo-rillonite (PS-PVA-MMT and plasticized starch-polyvinyl alcohol-cellulose nanocrystal (PS-PVA-NCC bionanocomposite flms. The results showed that adding MMT (7%, increased the ultimate tensile strenght from 4.2 MPa to 4.61 MPa, however, NCC (7% did not show signifcant (p < 0.5 effect on the ultimate tensile strength. Addition of MMT decreased while NCC  increased  the  strain-to-break of  the flms. The solubility in water decreased from 23.56% to 18.77% and 11.75% for the flms containing NCC and MMT, respectively. Similarly, water vapor permeability value of 7.41 ×10-7 g/m.h.Pa was dropped to 7.05×10-7 g/m.h.Pa and 6.19×10-7 g/m.h.Pa in flms containing NCC and MMT, respectively. The results showed that the effects of MMT on tensile and permeability were higher than NCC, which can be attributed to differences in the structure and hydrophilicity of two nanoparticles.

  13. Effect of phospholipid-based formulations of Boswellia serrata extract on the solubility, permeability, and absorption of the individual boswellic acid constituents present.

    Science.gov (United States)

    Hüsch, Jan; Gerbeth, Kathleen; Fricker, Gert; Setzer, Constanze; Zirkel, Jürgen; Rebmann, Herbert; Schubert-Zsilavecz, Manfred; Abdel-Tawab, Mona

    2012-10-26

    Boswellia serrata gum resin extracts are used widely for the treatment of inflammatory diseases. However, very low concentrations in the plasma and brain were observed for the boswellic acids (1-6, the active constituents of B. serrata). The present study investigated the effect of phospholipids alone and in combination with common co-surfactants (e.g., Tween 80, vitamin E-TPGS, pluronic f127) on the solubility of 1-6 in physiologically relevant media and on the permeability in the Caco-2 cell model. Because of the high lipophilicity of 1-6, the permeability experiments were adapted to physiological conditions using modified fasted state simulated intestinal fluid as apical (donor) medium and 4% bovine serum albumin in the basolateral (receiver) compartment. A formulation composed of extract/phospholipid/pluronic f127 (1:1:1 w/w/w) increased the solubility of 1-6 up to 54 times compared with the nonformulated extract and exhibited the highest mass net flux in the permeability tests. The oral administration of this formulation to rats (240 mg/kg) resulted in 26 and 14 times higher plasma levels for 11-keto-β-boswellic acid (1) and acetyl-11-keto-β-boswellic acid (2), respectively. In the brain, five times higher levels for 2 compared to the nonformulated extract were determined 8 h after oral administration.

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

    Science.gov (United States)

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

    2016-06-01

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

  15. Accelerated testing for studying pavement design and performance (FY 2001) : evaluation of the performance of permeable and semi-permeable unbound granular bases under Portland Cement Concrete Pavement (PCCP) slabs and alternate load transfer devices for

    Science.gov (United States)

    2003-11-01

    The objectives of this research are to determine the effect of unbound drainable base types on the performance of PCCP and the efficiency of fiber-reinforced polymer (FRP) dowels, compared to epoxy coated steel dowels, when retrofitted to re-establis...

  16. Dietary iron intake, iron status, and gestational diabetes.

    Science.gov (United States)

    Zhang, Cuilin; Rawal, Shristi

    2017-12-01

    Pregnant women are particularly vulnerable to iron deficiency and related adverse pregnancy outcomes and, as such, are routinely recommended for iron supplementation. Emerging evidence from both animal and population-based studies, however, has raised potential concerns because significant associations have been observed between greater iron stores and disturbances in glucose metabolism, including increased risk of type 2 diabetes among nonpregnant individuals. Yet, the evidence is uncertain regarding the role of iron in the development of gestational diabetes mellitus (GDM), a common pregnancy complication which has short-term and long-term adverse health ramifications for both women and their children. In this review, we critically and systematically evaluate available data examining the risk of GDM associated with dietary iron, iron supplementation, and iron status as measured by blood concentrations of several indicators. We also discuss major methodologic concerns regarding the available epidemiologic studies on iron and GDM. © 2017 American Society for Nutrition.

  17. Polypyridyl iron(II) complexes showing remarkable photocytotoxicity ...

    Indian Academy of Sciences (India)

    reported a high spin (S=5/2) ternary iron(III) complex. [Fe(BHA)(L)Cl] of a ... designed low-spin iron(II) complexes as a new class of ..... They were moderately soluble in methanol, ethanol and .... Cell permeable DCFDA on oxidation by cel-.

  18. A Reconciliation of Packed Column Permeability Data: Column Permeability as a Function of Particle Porosity

    Directory of Open Access Journals (Sweden)

    Hubert M. Quinn

    2014-01-01

    Full Text Available In his textbook teaching of packed bed permeability, Georges Guiochon uses mobile phase velocity as the fluid velocity term in his elaboration of the Darcy permeability equation. Although this velocity frame makes a lot of sense from a thermodynamic point of view, it is valid only with respect to permeability at a single theoretical boundary condition. In his more recent writings, however, Guiochon has departed from his long-standing mode of discussing permeability in terms of the Darcy equation and has embraced the well-known Kozeny-Blake equation. In this paper, his teaching pertaining to the constant in the Kozeny-Blake equation is examined and, as a result, a new correlation coefficient is identified and defined herein based on the velocity frame used in his teaching. This coefficient correlates pressure drop and fluid velocity as a function of particle porosity. We show that in their experimental protocols, Guiochon et al. have not adhered to a strict material balance of permeability which creates a mismatch of particle porosity and leads to erroneous conclusions regarding the value of the permeability coefficient in the Kozeny-Blake equation. By correcting the experimental data to properly reflect particle porosity we reconcile the experimental results of Guiochon and Giddings, resulting in a permeability reference chart which is presented here for the first time. This reference chart demonstrates that Guiochon’s experimental data, when properly normalized for particle porosity and other related discrepancies, corroborates the value of 267 for the constant in the Kozeny-Blake equation which was derived by Giddings in 1965.

  19. The role of palladium in iron based Fischer-Tropsch catalysts prepared by flame spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Minnermann, M.; Zielasek, V.; Baeumer, M. [Bremen Univ. (DE). Inst. of Applied and Physical Chemistry (IAPC); Pokhrei, S.; Maedler, L. [Bremen Univ. (DE). Foundation Inst. of Materials Science (IWT); Thiel, K. [Fraunhofer Institute for Manufactoring Technology and Applied Materials Research, Bremen (Germany)

    2011-07-01

    Flame spray pyrolysis (FSP) is a novel technique for the fabrication of nanostructured catalysts with far-reaching options to control structure and composition even in cases where complex composites need to be prepared. In this study, we took advantage of this technique to synthesize highly dispersed pure and Pd-doped iron oxide nanoparticles and investigated them as Fischer-Tropsch (FT) catalysts. By systematically varying the Pd content over a large range from 0.1 wt % to 10 wt %, we were able to directly analyze the influence of the Pd content on activity and selectivity. In addition to catalytic measurements, the structure and composition of the particles were characterized before and after these measurements, using transmission electron microscopy, adsorption measurements, X-ray diffraction and EXAFS. The comparison revealed, on the one hand, that small Pd clusters (diameter: 1-2 nm) evolve from initially homogeneously distributed Pd and, on the other hand, that the iron oxide transforms into iron carbides depending on the Pd content. The presence of Pd influences the particle size in the pristine samples (8 - 11 nm), resulting in specific surface areas that increase as the Pd content increases. However, after activation and reaction the specific surface areas become similar due to partial agglomeration and sintering. In a fixed bed FT reaction test, enhanced FT activity was observed with increasing Pd content while the selectivity shifts to longer chain hydrocarbons, mainly paraffins. (orig.)

  20. Contrast agents for MRI based on iron oxide nanoparticles prepared by laser pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Morales, M.P. E-mail: puerto@icmm.csic.es; Bomati-Miguel, O.; Perez de Alejo, R.; Ruiz-Cabello, J.; Veintemillas-Verdaguer, S.; O' Grady, K

    2003-10-01

    Colloidal suspensions of magnetic particles with application as contrast agents in magnetic resonance imaging have been prepared by coating iron oxide nanoparticles with dextran. The particles were prepared by laser-induced pyrolysis of iron pentacarbonyl vapors. By adjusting the experimental conditions, the particle and crystal size of the iron oxide nanoparticles were varied in the range 2-7 nm with a very narrow size distribution. The suspensions consisted of dextran-coated nanoparticle aggregates with a hydrodynamic diameter of around 50 nm and unimodal size distributions. It was observed that an important enhancement of the magnetic properties of the nanoparticles and the suspensions (saturation magnetization and susceptibility values) takes place as the particle and the crystallite size increases. Consequently, the {sup 1}H NMR relaxation times of the suspensions, characterized by the longitudinal (R{sub 1}) and transversal (R{sub 2}) relaxation rates, also increase with the crystal order. This effect was more pronounced for the values of R{sub 2}. The mechanism of MRI enhancement appears to be related to water protons diffusing within the inhomogeneous magnetic field created by the magnetic clusters. The global structure of the cluster, the anisotropy and the magnetic field around it are important factors affecting the value of R{sub 2}.

  1. Contrast agents for MRI based on iron oxide nanoparticles prepared by laser pyrolysis

    International Nuclear Information System (INIS)

    Morales, M.P.; Bomati-Miguel, O.; Perez de Alejo, R.; Ruiz-Cabello, J.; Veintemillas-Verdaguer, S.; O'Grady, K.

    2003-01-01

    Colloidal suspensions of magnetic particles with application as contrast agents in magnetic resonance imaging have been prepared by coating iron oxide nanoparticles with dextran. The particles were prepared by laser-induced pyrolysis of iron pentacarbonyl vapors. By adjusting the experimental conditions, the particle and crystal size of the iron oxide nanoparticles were varied in the range 2-7 nm with a very narrow size distribution. The suspensions consisted of dextran-coated nanoparticle aggregates with a hydrodynamic diameter of around 50 nm and unimodal size distributions. It was observed that an important enhancement of the magnetic properties of the nanoparticles and the suspensions (saturation magnetization and susceptibility values) takes place as the particle and the crystallite size increases. Consequently, the 1 H NMR relaxation times of the suspensions, characterized by the longitudinal (R 1 ) and transversal (R 2 ) relaxation rates, also increase with the crystal order. This effect was more pronounced for the values of R 2 . The mechanism of MRI enhancement appears to be related to water protons diffusing within the inhomogeneous magnetic field created by the magnetic clusters. The global structure of the cluster, the anisotropy and the magnetic field around it are important factors affecting the value of R 2

  2. Wear Resistant Thermal Sprayed Composite Coatings Based on Iron Self-Fluxing Alloy and Recycled Cermet Powders

    Directory of Open Access Journals (Sweden)

    Heikki SARJAS

    2012-03-01

    Full Text Available Thermal spray and WC-Co based coatings are widely used in areas subjected to abrasive wear. Commercial  cermet thermal spray powders for HVOF are relatively expensive. Therefore applying these powders in cost-sensitive areas like mining and agriculture are hindered. Nowadays, the use of cheap iron based self-fluxing alloy powders for thermal spray is limited. The aim of this research was to study properties of composite powders based on self-fluxing alloys and recycled cermets and to examine the properties of thermally sprayed (HVOF coatings from composite powders based on iron self-fluxing alloy and recycled cermet powders (Cr3C2-Ni and WC-Co. To estimate the properties of  recycled cermet powders, the sieving analysis, laser granulometry and morphology were conducted. For deposition of coatings High Velocity Oxy-Fuel spray was used. The structure and composition of powders and coatings were estimated by SEM and XRD methods. Abrasive wear performance of coatings was determined and compared with wear resistance of coatings from commercial powders. The wear resistance of thermal sprayed coatings from self-fluxing alloy and recycled cermet powders at abrasion is comparable with wear resistance of coatings from commercial expensive spray powders and may be an alternative in tribological applications in cost-sensitive areas.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1338

  3. Relative Permeability of Fractured Rock

    Energy Technology Data Exchange (ETDEWEB)

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  4. Lithium iron phosphate based battery – Assessment of the aging parameters and development of cycle life model

    International Nuclear Information System (INIS)

    Omar, Noshin; Monem, Mohamed Abdel; Firouz, Yousef; Salminen, Justin; Smekens, Jelle; Hegazy, Omar; Gaulous, Hamid; Mulder, Grietus; Van den Bossche, Peter; Coosemans, Thierry; Van Mierlo, Joeri

    2014-01-01

    Highlights: • Extended life cycle tests. • Investigation of the battery life cycle at different working conditions. • Investigation of the impact fast charging on the battery performances. • Extraction all required relationship for development of a cycle life model. • Development of a new life cycle model. - Abstract: This paper represents the evaluation of ageing parameters in lithium iron phosphate based batteries, through investigating different current rates, working temperatures and depths of discharge. From these analyses, one can derive the impact of the working temperature on the battery performances over its lifetime. At elevated temperature (40 °C), the performances are less compared to at 25 °C. The obtained mathematical expression of the cycle life as function of the operating temperature reveals that the well-known Arrhenius law cannot be applied to derive the battery lifetime from one temperature to another. Moreover, a number of cycle life tests have been performed to illustrate the long-term capabilities of the proposed battery cells at different discharge constant current rates. The results reveal the harmful impact of high current rates on battery characteristics. On the other hand, the cycle life test at different depth of discharge levels indicates that the battery is able to perform 3221 cycles (till 80% DoD) compared to 34,957 shallow cycles (till 20% DoD). To investigate the cycle life capabilities of lithium iron phosphate based battery cells during fast charging, cycle life tests have been carried out at different constant charge current rates. The experimental analysis indicates that the cycle life of the battery degrades the more the charge current rate increases. From this analysis, one can conclude that the studied lithium iron based battery cells are not recommended to be charged at high current rates. This phenomenon affects the viability of ultra-fast charging systems. Finally, a cycle life model has been developed, which

  5. Bioaccessibility, bioavailability and toxicity of commercially relevant iron- and chromium-based particles: in vitro studies with an inhalation perspective

    Directory of Open Access Journals (Sweden)

    Hedberg Yolanda

    2010-09-01

    Full Text Available Abstract Background Production of ferrochromium alloys (FeCr, master alloys for stainless steel manufacture, involves casting and crushing processes where particles inevitably become airborne and potentially inhaled. The aim of this study was to assess potential health hazards induced by inhalation of different well-characterized iron- and chromium-based particles, i.e. ferrochromium (FeCr, ferrosiliconchromium (FeSiCr, stainless steel (316L, iron (Fe, chromium (Cr, and chromium(IIIoxide (Cr2O3, in different size fractions using in vitro methods. This was done by assessing the extent and speciation of released metals in synthetic biological medium and by analyzing particle reactivity and toxicity towards cultured human lung cells (A549. Results The amount of released metals normalized to the particle surface area increased with decreasing particle size for all alloy particles, whereas the opposite situation was valid for particles of the pure metals. These effects were evident in artificial lysosomal fluid (ALF of pH 4.5 containing complexing agents, but not in neutral or weakly alkaline biological media. Chromium, iron and nickel were released to very low extent from all alloy particles, and from particles of Cr due to the presence of a Cr(III-rich protective surface oxide. Released elements were neither proportional to the bulk nor to the surface composition after the investigated 168 hours of exposure. Due to a surface oxide with less protective properties, significantly more iron was released from pure iron particles compared with the alloys. Cr was predominantly released as Cr(III from all particles investigated and was strongly complexed by organic species of ALF. Cr2O3 particles showed hemolytic activity, but none of the alloy particles did. Fine-sized particles of stainless steel caused however DNA damage, measured with the comet assay after 4 h exposure. None of the particles revealed any significant cytotoxicity in terms of cell death

  6. Magnetophotonic crystals based on yttrium-iron-garnet infiltrated opals: Magnetization-induced second-harmonic generation

    Science.gov (United States)

    Murzina, T. V.; Kim, E. M.; Kapra, R. V.; Moshnina, I. V.; Aktsipetrov, O. A.; Kurdyukov, D. A.; Kaplan, S. F.; Golubev, V. G.; Bader, M. A.; Marowsky, G.

    2006-01-01

    Three-dimensional magnetophotonic crystals (MPCs) based on artificial opals infiltrated by yttrium iron garnet (YIG) are fabricated and their structural, optical, and nonlinear optical properties are studied. The formation of the crystalline YIG inside the opal matrix is checked by x-ray analysis. Two templates are used for the infiltration by YIG: bare opals and those covered by a thin platinum film. Optical second-harmonic generation (SHG) technique is used to study the magnetization-induced nonlinear-optical properties of the composed MPCs. A high nonlinear magneto-optical Kerr effect in the SHG intensity is observed at the edge of the photonic band gap of the MPCs.

  7. Identification of the iron oxidation state and coordination geometry in iron oxide- and zeolite-based catalysts using pre-edge XAS analysis.

    Science.gov (United States)

    Boubnov, Alexey; Lichtenberg, Henning; Mangold, Stefan; Grunwaldt, Jan Dierk

    2015-03-01

    Analysis of the oxidation state and coordination geometry using pre-edge analysis is attractive for heterogeneous catalysis and materials science, especially for in situ and time-resolved studies or highly diluted systems. In the present study, focus is laid on iron-based catalysts. First a systematic investigation of the pre-edge region of the Fe K-edge using staurolite, FePO4, FeO and α-Fe2O3 as reference compounds for tetrahedral Fe(2+), tetrahedral Fe(3+), octahedral Fe(2+) and octahedral Fe(3+), respectively, is reported. In particular, high-resolution and conventional X-ray absorption spectra are compared, considering that in heterogeneous catalysis and material science a compromise between high-quality spectroscopic data acquisition and simultaneous analysis of functional properties is required. Results, which were obtained from reference spectra acquired with different resolution and quality, demonstrate that this analysis is also applicable to conventionally recorded pre-edge data. For this purpose, subtraction of the edge onset is preferentially carried out using an arctangent and a first-degree polynomial, independent of the resolution and quality of the data. For both standard and high-resolution data, multiplet analysis of pre-edge features has limitations due to weak transitions that cannot be identified. On the other hand, an arbitrary empirical peak fitting assists the analysis in that non-local transitions can be isolated. The analysis of the oxidation state and coordination geometry of the Fe sites using a variogram-based method is shown to be effective for standard-resolution data and leads to the same results as for high-resolution spectra. This method, validated by analysing spectra of reference compounds and their well defined mixtures, is finally applied to track structural changes in a 1% Fe/Al2O3 and a 0.5% Fe/BEA zeolite catalyst during reduction in 5% H2/He. The results, hardly accessible by other techniques, show that Fe(3+) is

  8. ARSENATE AND ARSENITE SORPTION AND ARSENITE OXIDATION BY IRON (II, III) HYDROXYCARBONATE GREEN RUST

    Science.gov (United States)

    Iron (II, III) hydroxycarbonate green rust is a major corrosion product of zerovalent iron that is being used in permeable reactive barriers to remediate groundwater arsenic contamination. To optimize the design of iron barriers, it is important to evaluate the influence of geoch...

  9. CHEMICAL INTERACTIONS OF ARSENATE, ARSENITE, PHOSPHATE, AND SILICATE WITH IRON (II, III) HYDROXYCARBONATE GREEN RUST

    Science.gov (United States)

    Granular zerovalent iron has been proposed to be used as a medium in permeable reactive barriers (PRBs) to remove arsenic from contaminated groundwater. Iron(II, III) hydroxycarbonate green rust (carbonate green rust, or CGR) is a major corrosion product of zerovalent iron under ...

  10. Mathematical Model to Predict the Permeability of Water Transport in Concrete Structure

    OpenAIRE

    Solomon Ndubuisi Eluozo

    2013-01-01

    Mathematical model to predict the permeability of water transport in concrete has been established, the model is to monitor the rate of water transport in concrete structure. The process of this water transport is based on the constituent in the mixture of concrete. Permeability established a relation on the influence of the micropores on the constituent that made of concrete, the method of concrete placement determine the rate of permeability deposition in concrete structure, permeability es...

  11. Effect of injection water quality on permeability of productive sands in Shaimsk group of oil fields

    Energy Technology Data Exchange (ETDEWEB)

    Andreeva, N I; Ivanov, V N; Lazarev, V N; Maksimov, V P

    1966-01-01

    Water from the Kond River is used to flood Shaimsk oil fields. Effect of raw and filtered waters on permeability of Shaimsk cores was experimentally determined. The raw river water contained 26 mg/liter of suspended solids, 10.7 mg/liter of total iron, 4.3 mg/liter of suspended iron oxide, and a pH of 6.4. The filtered river water was free of suspended solids and had a pH of 6.2. It was found that both raw and filtered water decreased core permeability. The unfiltered water decreased permeability 2 to 7 times more than the filtered water. Also, the decrease in permeability occurs much more slowly with the filtered than the unfiltered water. The effect of water on core permeability is essentially irreversible. Efforts to restore core permeability by reversing flow direction were not successful. Among the reasons for the permeability decrease were hydration and swelling of clays and evolution of gases from water in the cores. (10 refs.)

  12. New insights into iron deficiency and iron deficiency anemia.

    Science.gov (United States)

    Camaschella, Clara

    2017-07-01

    Recent advances in iron metabolism have stimulated new interest in iron deficiency (ID) and its anemia (IDA), common conditions worldwide. Absolute ID/IDA, i.e. the decrease of total body iron, is easily diagnosed based on decreased levels of serum ferritin and transferrin saturation. Relative lack of iron in specific organs/tissues, and IDA in the context of inflammatory disorders, are diagnosed based on arbitrary cut offs of ferritin and transferrin saturation and/or marker combination (as the soluble transferrin receptor/ferritin index) in an appropriate clinical context. Most ID patients are candidate to traditional treatment with oral iron salts, while high hepcidin levels block their absorption in inflammatory disorders. New iron preparations and new treatment modalities are available: high-dose intravenous iron compounds are becoming popular and indications to their use are increasing, although long-term side effects remain to be evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. A model of protocell based on the introduction of a semi-permeable membrane in a stochastic model of catalytic reaction networks

    Directory of Open Access Journals (Sweden)

    Marco Villani

    2013-09-01

    Full Text Available In this work we introduce some preliminary analyses on the role of a semi-permeable membrane in the dynamics of a stochastic model of catalytic reaction sets (CRSs of molecules. The results of the simulations performed on ensembles of randomly generated reaction schemes highlight remarkable differences between this very simple protocell description model and the classical case of the continuous stirred-tank reactor (CSTR. In particular, in the CSTR case, distinct simulations with the same reaction scheme reach the same dynamical equilibrium, whereas, in the protocell case, simulations with identical reaction schemes can reach very different dynamical states, despite starting from the same initial conditions.

  14. Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

    Science.gov (United States)

    Samadi-Maybodi, Abdolraouf; Rezaei, Vida; Rastegarzadeh, Saadat

    2015-02-05

    A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Pairing symmetries of several iron-based superconductor families and some similarities with cuprates and heavy-fermions

    Directory of Open Access Journals (Sweden)

    Das Tanmoy

    2012-03-01

    Full Text Available We show that, by using the unit-cell transformation between 1 Fe per unit cell to 2 Fe per unit cell, one can qualitatively understand the pairing symmetry of several families of iron-based superconductors. In iron-pnictides and iron-chalcogenides, the nodeless s±-pairing and the resulting magnetic resonance mode transform nicely between the two unit cells, while retaining all physical properties unchanged. However, when the electron-pocket disappears from the Fermi surface with complete doping in KFe2As2, we find that the unit-cell invariant requirement prohibits the occurrence of s±-pairing symmetry (caused by inter-hole-pocket nesting. However, the intra-pocket nesting is compatible here, which leads to a nodal d-wave pairing. The corresponding Fermi surface topology and the pairing symmetry are similar to Ce-based heavy-fermion superconductors. Furthermore, when the Fermi surface hosts only electron-pockets in KyFe2-xSe2, the inter-electron-pocket nesting induces a nodeless and isotropic d-wave pairing. This situation is analogous to the electron-doped cuprates, where the strong antiferromagnetic order creates similar disconnected electron-pocket Fermi surface, and hence nodeless d-wave pairing appears. The unit-cell transformation in KyFe2-xSe2 exhibits that the d-wave pairing breaks the translational symmetry of the 2 Fe unit cell, and thus cannot be realized unless a vacancy ordering forms to compensate for it. These results are consistent with the coexistence picture of a competing order and nodeless d-wave superconductivity in both cuprates and KyFe1.6Se2.

  16. Solution phase and membrane immobilized iron-based free radical reactions: Fundamentals and applications for water treatment

    Science.gov (United States)

    Lewis, Scott Romak

    Membrane-based separation processes have been used extensively for drinking water purification, wastewater treatment, and numerous other applications. Reactive membranes synthesized through functionalization of the membrane pores offer enhanced reactivity due to increased surface area at the polymer-solution interface and low diffusion limitations. Oxidative techniques utilizing free radicals have proven effective for both the destruction of toxic organics and non-environmental applications. Most previous work focuses on reactions in the homogeneous phase; however, the immobilization of reactants in membrane pores offers several advantages. The use of polyanions immobilized in a membrane or chelates in solution prevents ferric hydroxide precipitation at near-neutral pH, a common limitation of iron(Fe(II/III))-catalyzed hydrogen peroxide (H 2O2) decomposition. The objectives of this research are to develop a membrane-based platform for the generation of free radicals, degrade toxic organic compounds using this and similar solution-based reactions, degrade toxic organic compounds in droplet form, quantify hydroxyl radical production in these reactions, and develop kinetic models for both processes. In this study, a functionalized membrane containing poly(acrylic acid) (PAA) was used to immobilize iron ions and conduct free radical reactions by permeating H2O2 through the membrane. The membrane's responsive behavior to pH and divalent cations was investigated and modeled. The conversion of Fe(II) to Fe(III) in the membrane and its effect on the decomposition of hydrogen peroxide were monitored and used to develop kinetic models for predicting H2O2 decomposition in these systems. The rate of hydroxyl radical production, and hence contaminant degradation can be varied by changing the residence time, H2O2 concentration, and/or iron loading. Using these membrane-immobilized systems, successful removal of toxic organic compounds, such as pentachlorophenol (PCP), from water

  17. Geothermal Permeability Enhancement - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Joe Beall; Mark Walters

    2009-06-30

    The overall objective is to apply known permeability enhancement techniques to reduce the number of wells needed and demonstrate the applicability of the techniques to other undeveloped or under-developed fields. The Enhanced Geothermal System (EGS) concept presented in this project enhances energy extraction from reduced permeability zones in the super-heated, vapor-dominated Aidlin Field of the The Geysers geothermal reservoir. Numerous geothermal reservoirs worldwide, over a wide temperature range, contain zones of low permeability which limit the development potential and the efficient recovery of heat from these reservoirs. Low permeability results from poorly connected fractures or the lack of fractures. The Enhanced Geothermal System concept presented here expands these technologies by applying and evaluating them in a systematic, integrated program.

  18. IRON BIOAVAILABILITY IN CAMEROON WEANING FOODS AND ...

    African Journals Online (AJOL)

    Dialyzable iron value were enhanced with lime juice and significantly reduced by legumes (beans, soy bean, and groundnut), egg and egg yolk. Irish potatoes based diets were the best sources of dialyzable iron. Iron intakes were sufficient for most balanced diets to cover the recommended daily intakes of iron for children ...

  19. Process evaluation of a national school-based iron supplementation program for adolescent girls in Iran.

    Science.gov (United States)

    Kheirouri, Sorayya; Alizadeh, Mohammad

    2014-09-16

    Iron deficiency anemia remains as one of the most common nutritional problems in Iran, especially in women and girls. A process evaluation study of the national iron supplementation program targeting girls attending high schools was conducted to examine degree of exposure and satisfaction of the targets with the intervention components, and to assess the delivery (quantity), fidelity (quality), and environmental mediators of the intervention. Three assessment tools were developed and used for the process evaluation. A total of 8 schools were selected using a simple randomization method. Data were collected from students (n = 658 of 661 participants), teachers (n = 80), and school principals (n = 7 of 8). For the qualitative measures semi-structured interviews were conducted with the three study groups. Mean continuous compliance was 62.3%. Intolerance to pills and no water supply in classrooms accounted for 47.72% and 36.21% of the refusals, respectively. The refusal rate was significantly correlated (p knowledge of iron deficiency issues (p < 0.05). The odds of refusal in the absence of a classroom water supply were 2.02 (95% CI 1 · 044 to 3 · 900) times greater than for those classrooms with a water supply. Student exposure to the program's goal was satisfactory; however, delivery and fidelity of educational materials and training sessions were inadequate. The findings suggest that the methods of delivery and the fidelity of the program components, education materials and training sessions were insufficient and need to be improved. Additionally, specific attention has to be given to contextual factors to ensure the success of the program.

  20. Graphitic Layer Encapsulated Iron Based Non‐precious Catalysts for the Oxygen Reduction Reaction

    DEFF Research Database (Denmark)

    Zhong, Lijie

    consisting of uniform metallic nanoparticles encapsulated in graphitic layers. The thesis work is conducted aiming at three major objectives: further optimization of the pyrolysis to achieve improved performance of catalysts, investigation of the complex Fe-containing components, and exploration...... of the nitrogen functionalities. Two anions in the electrolyte are used to probe the iron containing active sites towards the ORR, cyanide (CN-) in alkaline and thiocyanate (SCN-) in acidic medium, which seem supporting the above conclusions. These findings provide new insights to the encapsulation structure...

  1. A numerical study of crack initiation in a bcc iron system based on dynamic bifurcation theory

    International Nuclear Information System (INIS)

    Li, Xiantao

    2014-01-01

    Crack initiation under dynamic loading conditions is studied under the framework of dynamic bifurcation theory. An atomistic model for BCC iron is considered to explicitly take into account the detailed molecular interactions. To understand the strain-rate dependence of the crack initiation process, we first obtain the bifurcation diagram from a computational procedure using continuation methods. The stability transition associated with a crack initiation, as well as the connection to the bifurcation diagram, is studied by comparing direct numerical results to the dynamic bifurcation theory [R. Haberman, SIAM J. Appl. Math. 37, 69–106 (1979)].

  2. Low temperature irradiation effects on iron boron based amorphous metallic alloys

    International Nuclear Information System (INIS)

    Audouard, A.

    1982-09-01

    Three Fe-B amorphous alloys (Fe 80 B 20 , Fe 27 Mo 2 B 20 and Fe 75 B 25 ) and the crystallized Fe 3 B alloy have been irradiated at the temperature of liquid hydrogen. Electron irradiation and irradiation by 10 B fission fragments induce point defects in amorphous alloys. These defects are characterized by an intrinsic resistivity and a formation volume. The threshold energy for the displacement of iron atoms has also been calculated. Irradiation by 235 U fission fragments induces some important structural modifications in the amorphous alloys [fr

  3. Powder metallurgical processing of magnetostrictive materials based on rare earth-iron intermetallic compounds

    International Nuclear Information System (INIS)

    Malekzadeh, M.

    1978-01-01

    Procedures are described for fabrication of high density rare earth-iron magnetostrictive compounds by powder metallurgical techniques. The fabrication involves a sequence of steps which includes preparing the pre-alloyed compounds, pulverizing them into a fine powder, compacting in suitable sizes and shapes, and sintering. Samples prepared by these procedures are carefully characterized by scanning electron microscopy, x-ray diffraction, dilatometry, and magnetic measurements. Process steps are found to exert important influences upon densities, microstructure and magnetic properties attained after densification. Investigations on a number of these process steps, including milling time and medium, sintering, and magnetic powder alignment are described

  4. Permeability, storage and hydraulic diffusivity controlled by earthquakes

    Science.gov (United States)

    Brodsky, E. E.; Fulton, P. M.; Xue, L.

    2016-12-01

    Earthquakes can increase permeability in fractured rocks. In the farfield, such permeability increases are attributed to seismic waves and can last for months after the initial earthquake. Laboratory studies suggest that unclogging of fractures by the transient flow driven by seismic waves is a viable mechanism. These dynamic permeability increases may contribute to permeability enhancement in the seismic clouds accompanying hydraulic fracking. Permeability enhancement by seismic waves could potentially be engineered and the experiments suggest the process will be most effective at a preferred frequency. We have recently observed similar processes inside active fault zones after major earthquakes. A borehole observatory in the fault that generated the M9.0 2011 Tohoku earthquake reveals a sequence of temperature pulses during the secondary aftershock sequence of an M7.3 aftershock. The pulses are attributed to fluid advection by a flow through a zone of transiently increased permeability. Directly after the M7.3 earthquake, the newly damaged fault zone is highly susceptible to further permeability enhancement, but ultimately heals within a month and becomes no longer as sensitive. The observation suggests that the newly damaged fault zone is more prone to fluid pulsing than would be expected based on the long-term permeability structure. Even longer term healing is seen inside the fault zone of the 2008 M7.9 Wenchuan earthquake. The competition between damage and healing (or clogging and unclogging) results in dynamically controlled permeability, storage and hydraulic diffusivity. Recent measurements of in situ fault zone architecture at the 1-10 meter scale suggest that active fault zones often have hydraulic diffusivities near 10-2 m2/s. This uniformity is true even within the damage zone of the San Andreas fault where permeability and storage increases balance each other to achieve this value of diffusivity over a 400 m wide region. We speculate that fault zones

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

    Directory of Open Access Journals (Sweden)

    Shichun Chi

    2015-01-01

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

  6. Redox-active media for permeable reactive barriers

    International Nuclear Information System (INIS)

    Sivavec, T.M.; Mackenzie, P.D.; Horney, D.P.; Baghel, S.S.

    1997-01-01

    In this paper, three classes of redox-active media are described and evaluated in terms of their long-term effectiveness in treating TCE-contaminated groundwater in permeable reactive zones. Zero-valent iron, in the form of recycled cast iron filings, the first class, has received considerable attention as a reactive media and has been used in about a dozen pilot- and full-scale subsurface wall installations. Criteria used in selecting commercial sources of granular iron, will be discussed. Two other classes of redox-active media that have not yet seen wide use in pilot- or full-scale installations will also be described: Fe(II) minerals and bimetallic systems. Fe(II) minerals, including magnetite (Fe 3 O 4 ), and ferrous sulfide (troilite, FeS), are redox-active and afford TCE reduction rates and product distributions that suggest that they react via a reductive mechanism similar to that which operates in the FeO system. Fe(II) species within the passive oxide layer coating the iron metal may act as electron transfer mediators, with FeO serving as the bulk reductant. Bimetallic systems, the third class of redox-active media, are commonly prepared by plating a second metal onto zero-valent iron (e.g., Ni/Fe and Pd/Fe) and have been shown to accelerate solvent degradation rates relative to untreated iron metal. The long-term effectiveness of this approach, however, has not yet been determined in groundwater treatability tests. The results of a Ni-plated iron column study using site groundwater indicate that a change in reduction mechanism (to catalytic dehydrohalogenation/hydrogenation) accounts for the observed rate enhancement. A significant loss in media reactivity was observed over time, attributable to Ni catalyst deactivation or poisoning. Zero-valent iron systems have not shown similar losses in reactivity in long-term laboratory, pilot or field investigations

  7. Least momentum space frustration as a condition for a ‘high Tc sweet spot’ in iron-based superconductors

    International Nuclear Information System (INIS)

    Usui, Hidetomo; Suzuki, Katsuhiro; Kuroki, Kazuhiko

    2012-01-01

    In the present paper, we describe how the band structure and the Fermi surface of iron-based superconductors vary as the Fe–As–Fe bond angle changes. We discuss how these Fermi surface configurations affect the superconductivity mediated by spin fluctuations, and show that, in several situations, frustration in the sign of the gap function arises due to the repulsive pairing interactions that requires a sign change of the order parameter. Such a frustration can result in nodes or very small gaps, and generally works destructively against superconductivity. Conversely, we propose that the optimal condition for superconductivity is realized for the Fermi surface configuration that gives the least frustration while maximizing the Fermi surface multiplicity. This is realized when there are three hole Fermi surfaces, where two of them have d XZ/YZ orbital character and one has d X 2 −Y 2 for all k z in the three-dimensional Brillouin zone. Looking at the band structures of various iron-based superconductors, the occurrence of such a ‘sweet spot’ situation is limited to a narrow window. (paper)

  8. Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline

    Directory of Open Access Journals (Sweden)

    Ameen Uddin Ammar

    2018-02-01

    Full Text Available Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy and electrochemical DC corrosion testing using the “three electrode system”. Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene and TiO2/GO (graphene oxide nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and “produce water” of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples.

  9. Experimental evidence for importance of Hund's exchange interaction for incoherence of charge carriers in iron-based superconductors

    Science.gov (United States)

    Fink, J.; Rienks, E. D. L.; Thirupathaiah, S.; Nayak, J.; van Roekeghem, A.; Biermann, S.; Wolf, T.; Adelmann, P.; Jeevan, H. S.; Gegenwart, P.; Wurmehl, S.; Felser, C.; Büchner, B.

    2017-04-01

    Angle-resolved photoemission spectroscopy is used to study the scattering rates of charge carriers from the hole pockets near Γ in the iron-based high-Tc hole-doped superconductors KxBa1 -xFe2As2 , x =0.4 , and KxEu1 -xFe2As2 , x =0.55 , and the electron-doped compound Ba (Fe1-xCox) 2As2 , x =0.075 . The scattering rate for any given band is found to depend linearly on the energy, indicating a non-Fermi-liquid regime. The scattering rates in the hole-doped compound are considerably higher than those in the electron-doped compounds. In the hole-doped systems the scattering rate of the charge carriers of the inner hole pocket is about three times higher than the binding energy, indicating that the spectral weight is heavily incoherent. The strength of the scattering rates and the difference between electron- and hole-doped compounds signals the importance of Hund's exchange coupling for correlation effects in these iron-based high-Tc superconductors. The experimental results are in qualitative agreement with theoretical calculations in the framework of combined density functional dynamical mean-field theory.

  10. Iron Intermetallic Phases in the Alloy Based on Al-Si-Mg by Applying Manganese

    Directory of Open Access Journals (Sweden)

    Podprocká R.

    2017-09-01

    Full Text Available Manganese is an effective element used for the modification of needle intermetallic phases in Al-Si alloy. These particles seriously degrade mechanical characteristics of the alloy and promote the formation of porosity. By adding manganese the particles are being excluded in more compact shape of “Chinese script” or skeletal form, which are less initiative to cracks as Al5FeSi phase. In the present article, AlSi7Mg0.3 aluminium foundry alloy with several manganese content were studied. The alloy was controlled pollution for achieve higher iron content (about 0.7 wt. % Fe. The manganese were added in amount of 0.2 wt. %, 0.6 wt. %, 1.0 wt. % and 1.4 wt. %. The influence of the alloying element on the process of crystallization of intermetallic phases were compared to microstructural observations. The results indicate that increasing manganese content (> 0.2 wt. % Mn lead to increase the temperature of solidification iron rich phase (TAl5FeSi and reduction this particles. The temperature of nucleation Al-Si eutectic increase with higher manganese content also. At adding 1.4 wt. % Mn grain refinement and skeleton particles were observed.

  11. Technologies for Decentralized Fluoride Removal: Testing Metallic Iron-based Filters

    Directory of Open Access Journals (Sweden)

    Arnaud Igor Ndé-Tchoupé

    2015-11-01

    Full Text Available Since the realization in the 1930s that elevated fluoride concentrations in drinking water can have detrimental effects on human health, new methods have been progressively developed in order to reduce fluoride to acceptable levels. In the developing world the necessity for filtration media that are both low-cost and sourced from locally available materials has resulted in the widespread use of bone char. Since the early 1990s metallic iron (Fe0 has received widespread use as both an adsorbent and a reducing agent for the removal of a wide range of contaminant species from water. The ion-selectivity of Fe0 is dictated by the positively charged surface of iron (hydroxides at circumneutral pH. This suggests that Fe0 could potentially be applied as suitable filter media for the negatively charged fluoride ion. This communication seeks to demonstrate from a theoretical basis and using empirical data from the literature the suitability of Fe0 filters for fluoride removal. The work concludes that Fe0-bearing materials, such as steel wool, hold good promise as low-cost, readily available and highly effective decentralized fluoride treatment materials.

  12. Oxygen kinetics and mechanism at electrocatalysts on the base of palladium-iron system

    International Nuclear Information System (INIS)

    Tarasevich, M.R.; Zhutaeva, G.V.; Bogdanovskaya, V.A.; Radina, M.V.; Ehrenburg, M.R.; Chalykh, A.E.

    2007-01-01

    Binary nanodispersed carbon XC72 supported PdFe catalysts with different atomic palladium-to-iron ratios are synthesized and studied in oxygen reduction reaction in acid solution at 60 o C. The Pd:Fe ratio was well controlled by the initial concentrations of Pd and Fe in the precursor solutions. The nanoparticles were characterized by transmission electron microscopy, X-ray diffractometry and X-ray photoelectron spectroscopy. The optimum Pd:Fe ratio for this reaction was determined to be 3:1. The comparison of activities of the catalysts with component ratios equaled 3:1 and 10:1 is shown that the activities are differed from each other by 10-15 times in advantage of catalyst with lesser content of palladium. This phenomenon can be related to the different particle size of both catalysts and different distribution of particles by size discovered by TEM method. The achievement of maximum activity near the ratio of Pd:Fe = 3:1 is due to as effect of alloy-forming and the influence of binary system component ratio and synthesis conditions on dispersity degree of metallic phase nanoparticles. Under optimal conditions of precursor mixture high-temperature pyrolysis, iron produces the stabilizing effect palladium. It gives rise to obtaining the uniform and finely divided (7-8 nm) metallic particles

  13. Improved performance of brazed plate heat exchangers made of stainless steel type EN 1.4401 (UNS S31600) when using a iron-based braze filler

    Energy Technology Data Exchange (ETDEWEB)

    Sjoedin, P. [Alfa Laval Materials, Lund (Sweden)

    2004-07-01

    The mechanical properties of brazed plate heat exchangers, made of stainless steel plates type EN 1.4401, brazed with a new iron-based braze filler ''AlfaNova'', have been evaluated. The results were compared with heat exchangers brazed with a copper (pure copper) and a nickel-based (MBF 51) braze filler. Their resistance against pressure- and temperature fatigue, which are important for the lifetime of a heat exchanger, and the burst pressure, which is important for pressure vessel approvals, were tested and evaluated. It was found that the pressure fatigue resistance was extraordinary good for the heat exchangers brazed the iron-based filler and its temperature fatigue resistance was better than those brazed with nickel-based braze filler and slightly lower than those brazed with copper. The highest burst pressures were achieved for the copper brazed units followed by the iron-brazed units and rearmost the nickel-brazed units. (orig.)

  14. Immobilization of gadolinium in iron borophosphate glasses and iron borophosphate based glass-ceramics: Implications for the immobilization of plutonium(Ⅲ)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fu, E-mail: wangfu@swust.edu.cn; Liao, Qilong, E-mail: liaoqilong@swust.edu.cn; Dai, Yunya; Zhu, Hanzhen

    2016-08-15

    Immobilization of gadolinium (Gd), a nonradioactive surrogate for Pu{sup 3+}, in iron borophosphate glasses/glass-ceramics (IBP glasses/glass-ceramics) has been investigated. The IBP glass containing 4 mol% Gd{sub 2}O{sub 3} is homogeneously amorphous. At higher Gd{sub 2}O{sub 3} concentrations, additional Gd is retained in the glasses as crystalline inclusions of monazite GdPO{sub 4} crystalline phase detected with X-ray diffraction. Moreover, Gd{sub 2}O{sub 3} addition increases the T{sub g} of the IBP glasses in glass formation range, which is consistent with the structural modification of the glasses. The structure of the Gd{sub 2}O{sub 3}-loaded IBP glasses/glass-ceramics is mainly based on pyrophosphate units. The chemical durability of Gd{sub 2}O{sub 3}-loaded IBP glasses/glass-ceramics is comparable to widely used borosilicate glass waste forms and the existence of monazite GdPO{sub 4} crystalline phase does not degrade the aqueous chemical durability of the IBP glasses/glass-ceramics. The Gd-loading results imply that the solubility should not be a limiting factor in processing nuclide Pu{sup 3+} if the formed crystalline phase(s) have high chemical durability. - Highlights: • Monazite GdPO{sub 4} are identified in the IBP glasses containing up to 6 mol% Gd{sub 2}O{sub 3}. • R{sub L} of the Gd{sub 2}O{sub 3}-loaded IBP glasses/glass-ceramics are about 10{sup −2} g m{sup −2} d{sup −1}. • Existence of GdPO{sub 4} does not degrade aqueous chemical durability of the IBP glass. • T{sub g} increases with increasing Gd{sub 2}O{sub 3} content in glass formation range. • IBP glasses are potential hosts for the immobilization of Pu{sup 3+} containing HLWs.

  15. Determination of filtrations and permeability of an earth dam

    International Nuclear Information System (INIS)

    Gomez, H.R.; Baro, G.B.; Gillen, Ricardo.

    1975-11-01

    The aim of this work was to measure with the aid of a radioactive tracer the speed flow of the water filtrating from Sumampa Dam in northeastern Catamarca, while being in operation, and with these data determine if the actual permeability corresponds to the projected one. Iodine-131 was used as tracer and periodical samples were taken from the down stream water in order to determine its activity concentration. In previous perforations ionic interchange resines were used so as to measure simultaneously the fixed Iodine-131. The permeability of the dam was calculated from the obtained speed based on time-concentration curves and applying Darcy formulas for permeability. (author) [es

  16. Electrical conductivity and magnetic permeability measurement of case hardened steels

    Science.gov (United States)

    Tian, Yong

    2015-03-01

    For case carburized steels, electrical conductivity and magnetic permeability profiles are needed to develop model-based case depth characterization techniques for the purpose of nondestructive quality control. To obtain fast and accurate measurement of these material properties, four-point potential drop approaches are applied on circular-shaped discs cut from steel rings with different case depths. First, a direct current potential drop (DCPD) approach is applied to measure electrical conductivity. Subsequently, an alternating current potential drop (ACPD) approach is used to measure magnetic permeability. Practical issues in measurement design and implementation are discussed. Depth profiles of electrical conductivity and magnetic permeability are reported.

  17. The Molecular Bases of the Dual Regulation of Bacterial Iron Sulfur Cluster Biogenesis by CyaY and IscX

    Directory of Open Access Journals (Sweden)

    Salvatore Adinolfi

    2018-02-01

    Full Text Available IscX (or YfhJ is a protein of unknown function which takes part in the iron-sulfur cluster assembly machinery, a highly specialized and essential metabolic pathway. IscX binds to iron with low affinity and interacts with IscS, the desulfurase central to cluster assembly. Previous studies have suggested a competition between IscX and CyaY, the bacterial ortholog of frataxin, for the same binding surface of IscS. This competition could suggest a link between the two proteins with a functional significance. Using a hybrid approach based on nuclear magnetic resonance, small angle scattering and biochemical methods, we show here that IscX is a modulator of the inhibitory properties of CyaY: by competing for the same site on IscS, the presence of IscX rescues the rates of enzymatic cluster formation which are inhibited by CyaY. The effect is stronger at low iron concentrations, whereas it becomes negligible at high iron concentrations. These results strongly suggest the mechanism of the dual regulation of iron sulfur cluster assembly under the control of iron as the effector.

  18. Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization

    International Nuclear Information System (INIS)

    Alves, Vinicius M.; Muratov, Eugene; Fourches, Denis; Strickland, Judy; Kleinstreuer, Nicole; Andrade, Carolina H.; Tropsha, Alexander

    2015-01-01

    Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R 2 = 0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q 2 ext = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. - Highlights: • It was compiled the largest publicly-available skin permeability dataset. • Predictive QSAR models were developed for skin permeability. • No concordance between skin sensitization and

  19. Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Vinicius M. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Muratov, Eugene [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Laboratory of Theoretical Chemistry, A.V. Bogatsky Physical–Chemical Institute NAS of Ukraine, Odessa 65080 (Ukraine); Fourches, Denis [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Strickland, Judy; Kleinstreuer, Nicole [ILS/Contractor supporting the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM), P.O. Box 13501, Research Triangle Park, NC 27709 (United States); Andrade, Carolina H. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Tropsha, Alexander, E-mail: alex_tropsha@unc.edu [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States)

    2015-04-15

    Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R{sup 2} = 0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q{sup 2}{sub ext} = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. - Highlights: • It was compiled the largest publicly-available skin permeability dataset. • Predictive QSAR models were developed for skin permeability. • No concordance between skin

  20. High-Performance Corrosion-Resistant Materials: Iron-Based Amorphous-Metal Thermal-Spray Coatings

    International Nuclear Information System (INIS)

    Farmer, J C; Haslam, J J; Wong, F; Ji, X; Day, S D; Branagan, D J; Marshall, M C; Meacham, B E; Buffa, E J; Blue, C A; Rivard, J K; Beardsley, M B; Weaver, D T; Aprigliano, L F; Kohler, L; Bayles, R; Lemieux, E J; Wolejsza, T M; Martin, F J; Yang, N; Lucadamo, G; Perepezko, J H; Hildal, K; Kaufman, L; Heuer, A H; Ernst, F; Michal, G M; Kahn, H; Lavernia, E J

    2004-01-01

    The multi-institutional High Performance Corrosion Resistant Materials (HPCRM) Team is cosponsored by the Defense Advanced Projects Agency (DARPA) Defense Science Office (DSO) and the Department of Energy (DOE) Office of Civilian Radioactive Waste Management (OCRWM), and has developed new corrosion-resistant, iron-based amorphous metals that can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The Fe-based corrosion-resistant, amorphous-metal coatings under development may prove of importance for applications on ships. Such coatings could be used as an ''integral drip shield'' on spent fuel containers, as well as protective coatings that could be applied over welds, thereby preventing exposure to environments that might cause stress corrosion cracking. In the future, such new high-performance iron-based materials could be substituted for more-expensive nickel-based alloys, thereby enabling a reduction in the $58-billion life cycle cost for the long-term storage of the Nation's spent nuclear fuel by tens of percent

  1. Fractal Theory for Permeability Prediction, Venezuelan and USA Wells

    Science.gov (United States)

    Aldana, Milagrosa; Altamiranda, Dignorah; Cabrera, Ana

    2014-05-01

    Inferring petrophysical parameters such as permeability, porosity, water saturation, capillary pressure, etc, from the analysis of well logs or other available core data has always been of critical importance in the oil industry. Permeability in particular, which is considered to be a complex parameter, has been inferred using both empirical and theoretical techniques. The main goal of this work is to predict permeability values on different wells using Fractal Theory, based on a method proposed by Pape et al. (1999). This approach uses the relationship between permeability and the geometric form of the pore space of the rock. This method is based on the modified equation of Kozeny-Carman and a fractal pattern, which allows determining permeability as a function of the cementation exponent, porosity and the fractal dimension. Data from wells located in Venezuela and the United States of America are analyzed. Employing data of porosity and permeability obtained from core samples, and applying the Fractal Theory method, we calculated the prediction equations for each well. At the beginning, this was achieved by training with 50% of the data available for each well. Afterwards, these equations were tested inferring over 100% of the data to analyze possible trends in their distribution. This procedure gave excellent results in all the wells in spite of their geographic distance, generating permeability models with the potential to accurately predict permeability logs in the remaining parts of the well for which there are no core samples, using even porority logs. Additionally, empirical models were used to determine permeability and the results were compared with those obtained by applying the fractal method. The results indicated that, although there are empirical equations that give a proper adjustment, the prediction results obtained using fractal theory give a better fit to the core reference data.

  2. Using artificial intelligence to predict permeability from petrographic data

    Energy Technology Data Exchange (ETDEWEB)

    Maqsood Ali; Adwait Chawathe [New Mexico Petroleum Recovery Research Centre (Mexico)

    2000-10-01

    Petrographic data collected during thin section analysis can be invaluable for understanding the factors that control permeability distribution. Reliable prediction of permeability is important for reservoir characterization. The petrographic elements (mineralogy, porosity types, cements and clays, and pore morphology) interact with each other uniquely to generate a specific permeability distribution. It is difficult to quantify accurately this interaction and its consequent effect on permeability, emphasizing the non-linear nature of the process. To capture these non-linear interactions, neural networks were used to predict permeability from petrographic data. The neural net was used as a multivariate correlative tool because of its ability to learn the non-linear relationships between multiple input and output variables. The study was conducted on the upper Queen formation called the Shattuck Member (Permian age). The Shattuck Member is composed of very fine-grained arkosic sandstone. The core samples were available from the Sulimar Queen and South Lucky Lake fields located in Chaves County, New Mexico. Nineteen petrographic elements were collected for each permeability value using a combined minipermeameter-petrographic technique. In order to reduce noise and overfitting the permeability model, these petrographic elements were screened, and their control (ranking) with respect to permeability was determined using fuzzy logic. Since the fuzzy logic algorithm provides unbiased ranking, it was used to reduce the dimensionality of the input variables. Based on the fuzzy logic ranking, only the most influential petrographic elements were selected as inputs for permeability prediction. The neural net was trained and tested using data from Well 1-16 in the Sulimar Queen field. Relying on the ranking obtained from the fuzzy logic analysis, the net was trained using the most influential three, five, and ten petrographic elements. A fast algorithm (the scaled conjugate

  3. Is outdoor work associated with elevated rates of cerebrovascular disease mortality? A cohort study based on iron-ore mining.

    Science.gov (United States)

    Björ, Ove; Jonsson, Håkan; Damber, Lena; Burström, Lage; Nilsson, Tohr

    2016-01-01

    A cohort study that examined iron ore mining found negative associations between cumulative working time employed underground and several outcomes, including mortality of cerebrovascular diseases. In this cohort study, and using the same group of miners, we examined whether work in an outdoor environment could explain elevated cerebrovascular disease rates. This study was based on a Swedish iron ore mining cohort consisting of 13,000 workers. Poisson regression models were used to generate smoothed estimates of standardized mortality ratios and adjusted rate ratios, both models by cumulative exposure time in outdoor work. The adjusted rate ratio between employment classified as outdoor work ≥25 years and outdoor work 0-4 years was 1.62 (95 % CI 1.07-2.42). The subgroup underground work ≥15 years deviated most in occurrence of cerebrovascular disease mortality compared with the external reference population: SMR (0.70 (95 % CI 0.56-0.85)). Employment in outdoor environments was associated with elevated rates of cerebrovascular disease mortality. In contrast, work in tempered underground employment was associated with a protecting effect.

  4. Dry sliding wear behaviour of heat treated iron based powder metallurgy steels with 0.3% Graphite + 2% Ni additions

    International Nuclear Information System (INIS)

    Tekeli, S.; Gueral, A.

    2007-01-01

    To determine the effect of various heat treatments on the microstructure and dry sliding wear behaviour of iron based powder metallurgy (PM) steels, atomized iron powder was mixed with 0.3% graphite + 2% Ni. The mixed powders were cold pressed at 700 MPa and sintered at 1200 deg. C for 30 min under pure Ar gas atmosphere. One of the sintered specimens was quenched from 890 deg. C and then tempered at 200 deg. C for 1 h. The other sintered specimens were annealed at different intercritical heat treatment temperatures of 728 and 790 deg. C and water quenched. Through this intercritical annealing heat treatment, the specimens with various ferrite + martensite volume fractions were produced. Wear tests were carried out on the quenched + tempered and intercritically annealed specimens under dry sliding conditions using a pin-on-disk type machine at constant load and speed and the results were compared in terms of microstructure, hardness and wear strength. It was seen that hardness and wear strength in intercritically annealed specimens were higher than that of quenched + tempered specimen

  5. Iron oxide nanoparticle-based magnetic resonance method to monitor release kinetics from polymeric particles with high resolution.

    Science.gov (United States)

    Chan, Minnie; Schopf, Eric; Sankaranarayanan, Jagadis; Almutairi, Adah

    2012-09-18

    A new method to precisely monitor rapid release kinetics from polymeric particles using super paramagnetic iron oxide nanoparticles, specifically by measuring spin-spin relaxation time (T(2)), is reported. Previously, we have published the formulation of logic gate particles from an acid-sensitive poly-β-aminoester ketal-2 polymer. Here, a series of poly-β-aminoester ketal-2 polymers with varying hydrophobicities were synthesized and used to formulate particles. We attempted to measure fluorescence of released Nile red to determine whether the structural adjustments could finely tune the release kinetics in the range of minutes to hours; however, this standard technique did not differentiate each release rate of our series. Thus, a new method based on encapsulation of iron oxide nanoparticles was developed, which enabled us to resolve the release kinetics of our particles. Moreover, the kinetics matched the relative hydrophobicity order determined by octanol-water partition coefficients. To the best of our knowledge, this method provides the highest resolution of release kinetics to date.

  6. Transmission electron microscopy characterization of laser-clad iron-based alloy on Al-Si alloy

    International Nuclear Information System (INIS)

    Mei, Z.; Wang, W.Y.; Wang, A.H.

    2006-01-01

    Microstructure characterization is important for controlling the quality of laser cladding. In the present work, a detailed microstructure characterization by transmission electron microscopy was carried out on the iron-based alloy laser-clad on Al-Si alloy and an unambiguous identification of phases in the coating was accomplished. It was found that there is austenite, Cr 7 C 3 and Cr 23 C 6 in the clad region; α-Al, NiAl 3 , Fe 2 Al 5 and FeAl 2 in the interface region; and α-Al and silicon in the heat-affected region. A brief discussion was given for their existence based on both kinetic and thermodynamic principles

  7. An advanced lithium-ion battery based on a graphene anode and a lithium iron phosphate cathode.

    Science.gov (United States)

    Hassoun, Jusef; Bonaccorso, Francesco; Agostini, Marco; Angelucci, Marco; Betti, Maria Grazia; Cingolani, Roberto; Gemmi, Mauro; Mariani, Carlo; Panero, Stefania; Pellegrini, Vittorio; Scrosati, Bruno

    2014-08-13

    We report an advanced lithium-ion battery based on a graphene ink anode and a lithium iron phosphate cathode. By carefully balancing the cell composition and suppressing the initial irreversible capacity of the anode in the round of few cycles, we demonstrate an optimal battery performance in terms of specific capacity, that is, 165 mAhg(-1), of an estimated energy density of about 190 Wh kg(-1) and a stable operation for over 80 charge-discharge cycles. The components of the battery are low cost and potentially scalable. To the best of our knowledge, complete, graphene-based, lithium ion batteries having performances comparable with those offered by the present technology are rarely reported; hence, we believe that the results disclosed in this work may open up new opportunities for exploiting graphene in the lithium-ion battery science and development.

  8. Structural and morphological investigation of magnetic nanoparticles based on iron oxides for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, Paula S. [Laboratorio Nacional de Luz Sincrotron (LNLS), Caixa Postal 6192, CEP 13083-970, Campinas-SP (Brazil)], E-mail: pferreira@lnls.br; Martins, Tatiana M. [Laboratorio Nacional de Luz Sincrotron (LNLS), Caixa Postal 6192, CEP 13083-970, Campinas-SP (Brazil); Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), Caixa Postal 6165, CEP 13083-970, Campinas-SP (Brazil); D' Souza-Li, Lilia [Laboratorio de Endocrinologia Pediatrica da Faculdade de Ciencias Medicas (FCM), UNICAMP, Caixa Postal 6111, CEP 13083-970, Campinas-SP (Brazil); Li, Li M. [Departamento de Neurologia da FCM, UNICAMP, Caixa Postal 6111, CEP 13083-970, Campinas-SP (Brazil); Metze, Konradin; Adam, Randall L. [Grupo interdisciplinar ' Patologia Analitica Celular' , Departamento de Anatomia Patologica da FCM, UNICAMP, Caixa Postal 6111, CEP 13083-970, Campinas-SP (Brazil); Knobel, Marcelo [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), Caixa Postal 6165, CEP 13083-970, Campinas-SP (Brazil); Zanchet, Daniela [Laboratorio Nacional de Luz Sincrotron (LNLS), Caixa Postal 6192, CEP 13083-970, Campinas-SP (Brazil)

    2008-05-01

    The present work reports the synthesis, characterization and properties of magnetic iron oxide nanoparticles for biomedical applications, correlating the nanoscale tunabilities in terms of size, structure, and magnetism. Magnetic nanoparticles in different conditions were prepared through thermal decomposition of Fe(acac){sub 3} in the presence of 1,2 hexadecanodiol (reducing agent) and oleic acid and oleylamine (ligands) in a hot organic solvent. The 2,3-dimercaptosuccinic acid (DMSA) was exchanged onto the nanocrystal surface making the particles stable in water. Nanoparticles were characterized by X-ray diffraction (XRD) measurements, small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Preliminary tests of incorporation of these nanoparticles in cells and their magnetic resonance image (MRI) were also carried out. The magnetization characterizations were made by isothermal magnetic measurements.

  9. Characterization of the impregnated iron based catalyst for direct coal liquefaction by EXAFS

    International Nuclear Information System (INIS)

    Yang Jianli; Zhun Jisheng; Liu Zhenyu; Zhong Bing

    2002-01-01

    Catalyst plays an important role in direct coal liquefaction (DCL). Iron catalysts are regarded as the most attractive catalysts for DCL. To maximize catalytic effect and minimize catalysts usage, ultra-fine size catalysts are preferred. The most effective catalysts are found to be those impregnated onto coal because of their high dispersion on coal surface and intimate contact with coal particles. Besides the physical size, chemical form of a catalyst or a catalyst precursor is also important in determination of DCL activity. The expended X-ray absorption fine structure spectroscopy technique were used in this study. It was shown that the catalysts tested are in nanomater range and have structure mainly in the form of γ-FeOOH and FeS, or possibly of Fe/O/S. The presence of γ-FeOOH can be attributed to the interaction between Fe and the oxygen containing groups of coal or oxygen from moisture

  10. Estimation of the effect of molybdenum on chemical and electrochemical stability of iron-based alloys

    International Nuclear Information System (INIS)

    Tyurin, A.G.

    2003-01-01

    The E-pH diagram for Mo-H 2 O system is made more precise. It is shown that a passivating film on molybdenum in weakly acid, neutral and alkali solutions may constitute MoO 2 only. In strongly acid solutions at anodic polarization the film should transform according to the following scheme: MoO 2 → Mo 4 O 11 → Mo 9 O 26 → MoO 3 . Sections of a Fe-Mo-O system phase diagram and a Fe-Mo-H 2 O system E-pH diagram at 25 deg C are plotted. MoO 2 is found to be a product of iron-molybdenum alloy oxidation in the air and in water. For the system of alloy Kh17N13M2-H 2 O the section of a E-pH diagram is plotted at 25 deg C [ru

  11. Formation of coatings from a liquid phase on the surface of iron-base alloys

    Directory of Open Access Journals (Sweden)

    A. Tatarek

    2008-12-01

    Full Text Available The study discloses the present state of the art regarding the technology and investigations of the phenomena that take place during the formation and growth of aluminum and zinc coatings hot-dip formed on iron products. In its cognitive aspect, the study offers an in-depth analysis of the partial processes that proceed in metal bath at the solid body – liquid metal interface. It is expected that the present study will help in a more detailed description of the respective phenomena and in full explanation of the mechanism of the coating growth, taking as an example the growth of aluminum coatings. The obtained results can serve as a background for some general conclusions regarding the thickness evolution process in other hot-dip coatings.

  12. Fractionation separation of human plasma proteins using HPLC with a homemade iron porphyrin based monolithic column.

    Science.gov (United States)

    Zhang, Doudou; Zhao, Yu; Lan, Dandan; Pang, Xiaomin; Bai, Ligai; Liu, Haiyan; Yan, Hongyuan

    2017-11-15

    In this work a polymer monolithic column was fabricated within the confines of a stainless steel column (50×4.6mm i.d.) via radical polymerization by using iron porphyrin and butyl methacrylate as co-monomers, ethylene glycol dimethacrylate as crosslinking agent, ethylene glycol, isopropyl alcohol and N, N-dimethylformamide as tri-porogens, benzoyl peroxide and N,N-dimethylaniline as initiators. The resulting monolithic column was characterized by elemental analysis, scanning electron microscopy, nitrogen adsorption BET surface area, and mercury intrusion porosimetry, respectively. Results showed that the homemade monolith occupied relatively uniform pore structure, low back pressure, and enhanced selectivity for proteins in complex bio-samples. The present work described a simple and efficient method for "fractionation separation" of human plasma proteins, and it is a promising separation method for complex bio-samples in proteomic research. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. MRI contrast demonstration of antigen-specific targeting with an iron-based ferritin construct

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, Edward G., E-mail: edward_walsh@brown.edu [Brown University, Department of Neuroscience (United States); Mills, David R. [Rhode Island Hospital/Warren Alpert Medical School of Brown University, Division of Hematology and Oncology, Department of Medicine (United States); Lim, Sierin; Sana, Barindra [Nanyang Technological University, Division of Bioengineering (Singapore); Brilliant, Kate E. [Rhode Island Hospital/Warren Alpert Medical School of Brown University, Division of Hematology and Oncology, Department of Medicine (United States); Park, William K. C. [Rhode Island Hospital, Department of Diagnostic Imaging (United States)

    2013-01-15

    A genetically modified ferritin has been examined for its properties as a tumor-selective magnetic resonance imaging (MRI) contrast agent. The engineered ferritin described herein was derived from Archaeoglobus fulgidus (AfFtn-AA), which stores a significantly greater quantity of iron than wild-type ferritins. Relaxivity measurements were taken at 3 Tesla of ferritin particles uniformly distributed in an agarose gel to assess relaxivities r{sub 1} and r{sub 2}. The r{sub 1} and r{sub 2} values of the uniformly distributed modified ferritin were significantly higher (r{sub 1} = 1,290 mM{sup -1} s{sup -1} and r{sub 2} = 5,740 mM{sup -1} s{sup -1}) than values observed for wild-type ferritin (e.g., horse spleen, r{sub 1} = 0.674 mM{sup -1} s{sup -1}, r{sub 2} = 95.54 mM{sup -1} s{sup -1}). The modified iron-enriched ferritin (14.5 nm diameter) was conjugated with a monoclonal antibody (10 nm length) against rat Necl-5, a cell surface glycoprotein overexpressed by many epithelial cancers. In vitro studies showed strong reactivity of the assembled nanoconjugate to transformed Necl-5 positive rat prostate epithelial cells. Furthermore, MRI demonstrated a significant T{sub 2} contrast with negligible T{sub 1} effect when bound to cells. These findings highlight the utility of the modified ferritin construct as a novel MRI contrast agent that can be manipulated to target antigen-specific tissues.

  14. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  15. Bentonite Permeability at Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Katherine A. Daniels

    2017-01-01

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

  16. [Iron and invasive fungal infection].

    Science.gov (United States)

    Álvarez, Florencio; Fernández-Ruiz, Mario; Aguado, José María

    2013-01-01

    Iron is an essential factor for both the growth and virulence of most of microorganisms. As a part of the innate (or nutritional) immune system, mammals have developed different mechanisms to store and transport this element in order to limit free iron bioavailability. To survive in this hostile environment, pathogenic fungi have specific uptake systems for host iron sources, one of the most important of which is based on the synthesis of siderophores-soluble, low-molecular-mass, high-affinity iron chelators. The increase in free iron that results from iron-overload conditions is a well-established risk factor for invasive fungal infection (IFI) such as mucormycosis or aspergillosis. Therefore, iron chelation may be an appealing therapeutic option for these infections. Nevertheless, deferoxamine -the first approved iron chelator- paradoxically increases the incidence of IFI, as it serves as a xeno-siderophore to Mucorales. On the contrary, the new oral iron chelators (deferiprone and deferasirox) have shown to exert a deleterious effect on fungal growth both in vitro and in animal models. The present review focuses on the role of iron metabolism in the pathogenesis of IFI and summarises the preclinical data, as well as the limited clinical experience so far, in the use of new iron chelators as treatment for mucormycosis and invasive aspergillosis. Copyright © 2012 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

  17. Hydrogen production from natural gas using an iron-based chemical looping technology: Thermodynamic simulations and process system analysis

    International Nuclear Information System (INIS)

    Kathe, Mandar V.; Empfield, Abbey; Na, Jing; Blair, Elena; Fan, Liang-Shih

    2016-01-01

    Highlights: • Design of iron-based chemical looping process using moving bed for H_2 from CH_4. • Auto-thermal operation design using thermodynamic rationale for 90% carbon capture. • Cold gas efficiency: 5% points higher than Steam Methane Reforming baseline case. • Net thermal efficiency: 6% points higher than Steam Methane Reforming baseline case. • Sensitivity analysis: Energy recovery scheme, operating pressure, no carbon capture. - Abstract: Hydrogen (H_2) is a secondary fuel derived from natural gas. Currently, H_2 serves as an important component in refining operations, fertilizer production, and is experiencing increased utilization in the transportation industry as a clean combustion fuel. In recent years, industry and academia have focused on developing technology that reduces carbon emissions. As a result, there has been an increase in the technological developments for producing H_2 from natural gas. These technologies aim to minimize the cost increment associated with clean energy production. The natural gas processing chemical looping technology, developed at The Ohio State University (OSU), employs an iron-based oxygen carrier and a novel gas–solid counter-current moving bed reactor for H_2 production. Specifically, this study examines the theoretical thermodynamic limits for full conversion of natural gas through iron-based oxygen carrier reactions with methane (CH_4), by utilizing simulations generated with ASPEN modeling software. This study initially investigates the reducer and the oxidizer thermodynamic phase diagrams then derives an optimal auto-thermal operating condition for the complete loop simulation. This complete loop simulation is initially normalized for analysis on the basis of one mole of carbon input from natural gas. The H_2 production rate is then scaled to match that of the baseline study, using a full-scale ASPEN simulation for computing cooling loads, water requirements and net parasitic energy consumption. The

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

    International Nuclear Information System (INIS)

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

    1994-03-01

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

  19. Experimental Validation of a Permeability Model for Enrichment Membranes

    International Nuclear Information System (INIS)

    Orellano, Pablo; Brasnarof, Daniel; Florido Pablo

    2003-01-01

    An experimental loop with a real scale diffuser, in a single enrichment-stage configuration, was operated with air at different process conditions, in order to characterize the membrane permeability.Using these experimental data, an analytical geometric-and-morphologic-based model was validated.It is conclude that a new set of independent measurements, i.e. enrichment, is necessary in order to fully characterize diffusers, because of its internal parameters are not univocally determinated with permeability experimental data only

  20. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... risk for iron-deficiency anemia, including: Vegetarian or vegan eating patterns. Not eating enough iron-rich foods, ... iron-fortified foods that have iron added. Vegetarian diets can provide enough iron if you choose nonmeat ...

  1. Permeability enhancement by shock cooling

    Science.gov (United States)

    Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

    2015-04-01

    The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of

  2. What Is the Real Public Health Significance of Iron Deficiency and Iron Deficiency Anaemia in Croatia? A Population-Based Observational Study on Pregnant Women at Early Pregnancy from Eastern Croatia.

    Science.gov (United States)

    Banjari, Ines; Kenjerić, Daniela; Mandić, Milena L

    2015-06-01

    Studies imply that significance of iron deficiency (ID) and iron deficiency anaemia (IDA) for pregnancy outcomes is especially highlighted in the early pregnancy. Prevalence around the world varies widely, however, no data is available up to date for Croatia or neighbouring countries. Therefore, the objective was to determine the prevalence of ID and IDA among pregnant women from Croatia at the first trimester. Also, the aim was to compare two criterions; the World Health Organization (WHO) one and the clinical one. Randomised observational population based study was set up and 265 pregnant women at the first trimester were enrolled. Based on the WHO criteria, 17.7% on haemoglobin basis and 18.5% on haematocrit basis had either ID or IDA. Clinical criteria showed that even 32.8% had either ID or IDA (transferrin saturation pregnancy as iron deficient, presents a potentially high risk for the pregnancy outcomes, especially in terms of a newborn, and it is fully justified to treat them as diseases of public health significance. Copyright© by the National Institute of Public Health, Prague 2015.

  3. Antiphase Fermi-surface modulations accompanying displacement excitation in a parent compound of iron-based superconductors

    Science.gov (United States)

    Okazaki, Kozo; Suzuki, Hakuto; Suzuki, Takeshi; Yamamoto, Takashi; Someya, Takashi; Ogawa, Yu; Okada, Masaru; Fujisawa, Masami; Kanai, Teruto; Ishii, Nobuhisa; Itatani, Jiro; Nakajima, Masamichi; Eisaki, Hiroshi; Fujimori, Atsushi; Shin, Shik

    2018-03-01

    We investigate the transient electronic structure of BaFe2As2 , a parent compound of iron-based superconductors, by time- and angle-resolved photoemission spectroscopy. In order to probe the entire Brillouin zone, we utilize extreme ultraviolet photons and observe photoemission intensity oscillation with the frequency of the A1 g phonon which is antiphase between the zone-centered hole Fermi surfaces (FSs) and zone-cornered electron FSs. We attribute the antiphase behavior to the warping in one of the zone-centered hole FSs accompanying the displacement of the pnictogen height and find that this displacement is the same direction as that induced by substitution of P for As, where superconductivity is induced by a structural modification without carrier doping in this system.

  4. Spin resonance in the new-structure-type iron-based superconductor CaKFe4As4

    International Nuclear Information System (INIS)

    Iida, Kazuki; Ishikado, Motoyuki; Nagai, Yuki; Yoshida, Hiroyuki; Christianson, Andrew D.; Murai, Naoki; Kawashima, Kenji; Yoshida, Yoshiyuki; Eisaki, Hiroshi; Iyo, Akira

    2017-01-01

    The dynamical spin susceptibility in the new-structure-type iron-based superconductor CaKFe 4 As 4 was investigated by using a combination of inelastic neutron scattering (INS) measurements and random phase approximation (RPA) calculations. Powder INS measurements show that the spin resonance at Q res = 1.17(1) Å -1 , corresponding to the (π, π) nesting wave vector in tetragonal notation, evolves below T c . The characteristic energy of the spin resonance E res = 12.5 meV is smaller than twice the size of the superconducting gap (2Δ). The broad energy feature of the dynamical susceptibility of the spin resonance can be explained by the RPA calculations, in which the different superconducting gaps on different Fermi surfaces are taken into account. Our INS and PRA studies demonstrate that the superconducting pairing nature in CaKFe 4 As 4 is the s ± symmetry. (author)

  5. Synchrotron radiation-based x-ray analysis of bronze artifacts from an Iron Age site in the Judean hills

    International Nuclear Information System (INIS)

    Friedman, E. S.; Brody, A. J.; Young, M. L.; Almer, J. D.; Serge, C. U.; Mini, S. M.

    2008-01-01

    Seven bronze bangles from Tell en-Nasbeh, northern Judah, were investigated to understand the phase composition and manufacturing process of the artifacts, and possibly suggest a provenance for their origin. Synchrotron x-ray radiation diffraction (XRD) and fluorescence (XRF) were used in the analysis to avoid any destructive sampling and at the same time penetrate through the surface into the core metal. These techniques enabled us to determine that the bangles were not just tin bronze, but leaded tin bronze. Based on excavation reports, it is unlikely that the metal objects were manufactured locally at Tell en-Nasbeh; rather, preliminary XRD and XRF data point towards the neighboring region of Edom as their origin. Despite their political enmity during the Iron Age II, the data suggest that Judahite social demands for bronze may have fostered a strong economic relationship between these two polities

  6. Removal of As, Cd, Cr, Cu, Ni and Zn from polluted water using an iron based sorbent

    DEFF Research Database (Denmark)

    Genc-Fuhrman, Hülya; Wu, P.; Zhou, Y.

    2008-01-01

    In this study fixed-bed sorption filters are filled with an iron based sorbent (ferrosorp plus, FP) and used to remove a range of heavy metals (i.e. As, Cd, Cr, Cu, Ni, and Zn) from polluted water. It is found that FP is very effective at simultaneous removal of the heavy metals, and the magnitude...... inflow pH of 6.8 and heavy metal concentration of ≈2.8 μM. It is concluded that FP has high affinity to heavy metals and it can be used (e.g. as a filter medium) to treat waters containing a wide range of heavy metals, e.g. stormwater, industrial wastewater....

  7. Structural phase transitions in Iron - based superconductors BaFe2-xCrxAs2 under high pressure

    International Nuclear Information System (INIS)

    Uhoya, W.O.; Montgomery, J.M.; Samudrala, G.K.; Tsoi, G.M.; Vohra, Y.K.; Sefar, A.S.

    2011-01-01

    Pure BaFe 2 As 2 with the ThCr 2 Si 2 -type crystal structure under ambient conditions is known to superconduct under high pressure and undergo an isostructural phase transition from tetragonal to collapsed tetragonal phase which is accompanied by anomalous compressibility effects. Presently, there is no reported work on the crystal structure on any of the chemically doped 122- iron based superconductors under high pressure. We have carried out the electrical resistance measurements and high pressure X-ray diffraction studies on Chromium doped samples of BaFe 2-x Cr x As 2 (x = 0, 0.05, 0.15, 0.4, 0.61) to a pressure of 75 GPa and a temperature of 10K using a synchrotron source and designer diamond anvils, so as to investigate the influence of chemical doping and high pressure on crystal structure and superconductivity

  8. The effect of different surface materials on runoff quality in permeable pavement systems.

    Science.gov (United States)

    Li, Haiyan; Li, Zhifei; Zhang, Xiaoran; Li, Zhuorong; Liu, Dongqing; Li, Tanghu; Zhang, Ziyang

    2017-09-01

    To investigate the effect of different permeable pavement surface materials on the removal of pollutants from urban storm-runoff, six commonly surface materials (porous asphalt, porous concrete, cement brick, ceramic brick, sand base brick, and shale brick) were selected in this study and the research was carried out by column experiments. Except the concentrations of total suspended solids (TSS), chemical oxygen demand (COD), ammonia nitrogen (NH 4 -N), nitrate nitrogen (NO 3 -N), total nitrogen (TN), and total phosphorus (TP) in the influent and effluent that were measured, the removal mechanism of pollutants was discussed further. The results indicate that the surface materials influence the removal efficiency of pollutants greatly and have different effects on certain pollutant. Furthermore, the physical interception and adsorption would be the main mechanism for the removal of pollutants from runoff. For example, for all surface materials, the average removal efficiency of TSS is nearly about 90.0% because of physical interception. Due to the amount of iron oxide, the removal efficiency of COD, NO 3 -N, and TN of shale brick was 88.2, 35.1, and 17.5%, respectively. NH 4 -N and TN can be easily removed by porous asphalt due to the high content of organic matter. By lacking of useful adsorption sites, all the surface materials had little effect on the removal of TP from runoff. This research could offer useful guidelines for the better design of permeable pavement system and promote the insight into the removal mechanism of pollutants in permeable pavement system. Graphical abstract Different types of materials for the different types of pollutants in the runoff purification capacity were significantly different, overall, shale brick and porous asphalt Shale bricks and porous asphalt have a better purification effect according to the six kinds of materials.

  9. Estimation of permeability and permeability anisotropy in horizontal wells through numerical simulation of mud filtrate invasion

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Nelson [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Exploracao e Producao; Altman, Raphael; Rasmus, John; Oliveira, Jansen [Schlumberger Servicos de Petroleo Ltda., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    This paper describes how permeability and permeability anisotropy is estimated in horizontal wells using LWD (logging-while-drilling) laterolog resistivity data. Laterolog-while-drilling resistivity passes of while-drilling and timelapse (while reaming) were used to capture the invasion process. Radial positions of water based mud invasion fronts were calculated from while-drilling and reaming resistivity data. The invasion process was then recreated by constructing forward models with a fully implicit, near-wellbore numerical simulation such that the invasion front at a given time was consistent with the position of the front predicted by resistivity inversions. The radial position of the invasion front was shown to be sensitive to formation permeability. The while-drilling environment provides a fertile scenario to investigate reservoir dynamic properties because mud cake integrity and growth is not fully developed which means that the position of the invasion front at a particular point in time is more sensitive to formation permeability. The estimation of dynamic formation properties in horizontal wells is of particular value in marginal fields and deep-water offshore developments where running wireline and obtaining core is not always feasible, and where the accuracy of reservoir models can reduce the risk in field development decisions. (author)

  10. Antibacterial properties of an iron-based hemostatic agent in vitro and in a rat wound model.

    Science.gov (United States)

    Bracho, David O; Barsan, Lauren; Arekapudi, Subramanyeswara R; Thompson, John A; Hen, John; Stern, Susan A; Younger, John G

    2009-07-01

    Topical hemostatic agents are currently employed on the battlefield for control of major hemorrhage and have potential for use in civilian settings. Some of these compounds may also be antibacterial. Given the behavior of these compounds, the purpose of this study was to assess the potential antibacterial properties of an iron oxyacid-based topical hemostatic agent against three problematic species of wound-contaminating microorganisms: Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and methicillin-resistant Staphylococcus epidermidis. Bacteria were treated in vitro with the test powder for 30 minutes and then assessed for viabi