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Articles de revues sur le sujet "64Cu, low metal content"
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Martin, Sebastian, Stephan Maus, Tobias Stemler, Florian Rosar, Fadi Khreish, Jason P. Holland, Samer Ezziddin et Mark D. Bartholomä. « Proof-of-Concept Study of the NOTI Chelating Platform : Preclinical Evaluation of 64Cu-Labeled Mono- and Trimeric c(RGDfK) Conjugates ». Molecular Imaging and Biology 23, no 1 (27 août 2020) : 95–108. http://dx.doi.org/10.1007/s11307-020-01530-8.
Texte intégralRésumé :
Abstract Purpose We recently developed a chelating platform based on the macrocycle 1,4,7-triazacyclononane with up to three five-membered azaheterocyclic arms for the preparation of 68Ga- and 64Cu-based radiopharmaceuticals. Based on this platform, the chelator scaffold NOTI-TVA with three additional carboxylic acid groups for bioconjugation was synthesized and characterized. The primary aims of this proof-of-concept study were (1) to evaluate if trimeric radiotracers on the basis of the NOTI-TVA 6 scaffold can be developed, (2) to determine if the additional substituents for bioconjugation at the non-coordinating NH atoms of the imidazole residues of the building block NOTI influence the metal binding properties, and (3) what influence multiple targeting vectors have on the biological performance of the radiotracer. The cyclic RGDfK peptide that specifically binds to the αvß3 integrin receptor was selected as the biological model system. Procedures Two different synthetic routes for the preparation of NOTI-TVA 6 were explored. Three c(RGDfK) peptide residues were conjugated to the NOTI-TVA 6 building block by standard peptide chemistry providing the trimeric bioconjugate NOTI-TVA-c(RGDfK)39. Labeling of 9 with [64Cu]CuCl2 was performed manually at pH 8.2 at ambient temperature. Binding affinities of Cu-8, the Cu2+ complex of the previously described monomer NODIA-Me-c(RGDfK) 8, and the trimer Cu-9 to integrin αvß3 were determined in competitive cell binding experiments in the U-87MG cell line. The pharmacokinetics of both 64Cu-labeled conjugates [64Cu]Cu-8 and [64Cu]Cu-9 were determined by small-animal PET imaging and ex vivo biodistribution studies in mice bearing U-87MG xenografts. Results Depending on the synthetic route, NOTI-TVA 6 was obtained with an overall yield up to 58 %. The bioconjugate 9 was prepared in 41 % yield. Both conjugates [64Cu]Cu-8 and [64Cu]Cu-9 were radiolabeled quantitatively at ambient temperature in high molar activities of Am ~ 20 MBq nmol−1 in less than 5 min. Competitive inhibitory constants IC50 of c(RDGfK) 7, Cu-8, and Cu-9 were determined to be 159.5 ± 1.3 nM, 256.1 ± 2.1 nM, and 99.5 ± 1.1 nM, respectively. In small-animal experiments, both radiotracers specifically delineated αvß3 integrin-positive U-87MG tumors with low uptake in non-target organs and rapid blood clearance. The trimer [64Cu]Cu-9 showed a ~ 2.5-fold higher tumor uptake compared with the monomer [64Cu]Cu-8. Conclusions Functionalization of NOTI at the non-coordinating NH atoms of the imidazole residues for bioconjugation was straightforward and allowed the preparation of a homotrimeric RGD conjugate. After optimization of the synthesis, required building blocks to make NOTI-TVA 6 are now available on multi-gram scale. Modifications at the imidazole groups had no measurable impact on metal binding properties in vitro and in vivo suggesting that the NOTI scaffold is a promising candidate for the development of 64Cu-labeled multimeric/multifunctional radiotracers.
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Wagener, Karolin, Dennis Renisch, Meike Schinnerer, Matthias Worm, Yvonne Jakob, Klaus Eberhardt et Frank Rösch. « Copper-catalyzed click reactions : quantification of retained copper using 64Cu-spiked Cu(I), exemplified for CuAAC reactions on liposomes ». Radiochimica Acta 107, no 7 (26 juillet 2019) : 547–54. http://dx.doi.org/10.1515/ract-2018-3000.
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Abstract The Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is a powerful, highly reliable and selective reaction which allows for a rapid synthesis in high yields and under mild conditions (pH, temperature). However, the cytotoxicity of copper requires its complete removal prior to an application in vivo. This is an issue especially when it comes to CuAAC reactions on macromolecular structures or drug delivery systems, as copper might be retained by these systems. Thus, a quantification of the final copper content of these systems is inevitable, which we exemplified for a CuAAC reaction on liposomes using 64Cu-spiked Cu(I). In this respect, a Cu(II) nitrate solution was irradiated at the TRIGA Mark II research reactor Mainz to obtain c.a. [64Cu]Cu(II). The irradiated solution was directly used for a CuAAC on liposomes. After purification, their copper content was calculated utilizing γ-ray spectrometry. Only 0.018% of the added 64Cu-activity was still present in the liposome containing fractions after purification. This refers to a total amount of copper of 0.17 ng. The amount of retained copper is so low, that an in vivo application of the liposomes is absolutely reasonable. Besides this particular study, the experimental methodology may be applied to study many other CuAAC reactions, used for the synthesis of radiolabeled or non-radioactive species, which are intended for human applications.
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Kamal, A., S. M. D. Naqvi et F. Khan. « Production of Low Metal Content Re-refined Lubricating Oil ». Petroleum Science and Technology 27, no 16 (30 septembre 2009) : 1810–20. http://dx.doi.org/10.1080/10916460802624039.
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Ruiz-Trejo, Enrique, Paul Boldrin, Alexandra Lubin, Farid Tariq, Sarah Fearn, Richard Chater, Stuart N. Cook et al. « Novel Composite Cermet for Low-Metal-Content Oxygen Separation Membranes ». Chemistry of Materials 26, no 13 (20 juin 2014) : 3887–95. http://dx.doi.org/10.1021/cm501490n.
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Reid, Scott D., et D. G. McDonald. « Metal Binding Activity of the Gills of Rainbow Trout (Oncorhynchus mykiss) ». Canadian Journal of Fisheries and Aquatic Sciences 48, no 6 (1 juin 1991) : 1061–68. http://dx.doi.org/10.1139/f91-125.
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The objective of this study was to characterize the metal binding of the external gill surface in an attempt to interrelate metal chemistry, gill surface binding activity, and possibly metal toxicity. Individual gill arches from adult rainbow trout (Oncorhynchus mykiss) were exposed to various concentrations of either 140La, 45Ca, 109Cd, or 64Cu. The apparent dissociation constant (KD) and capacity (Bmax) of the external gill surface for the metals was calculated using Scatchard plot analysis. Half-saturation time (t1/2) and binding cooperativity (Hn) were also determined. The KD for gill metal binding ranged from 0.31 ± 0.02 mM for La3+ (high affinity) to 4.3 ± 0.04 mM for Cu2+ (low affinity). The gill binding affinity for Ca2+ was threefold lower than for La3+, but was similar to that for Cd2+. The gills had the lowest affinity for Cu2+, almost 14 times lower than that for La3+. Bmax for La3+ was found to be significantly lower than for any other metal (0.14 ± 0.001 μmol∙g−1), while nearly seven times as much Cu2+ was accumulated by the gills compared with La3+, The Ca2+ and Cd2+Bmax estimates were intermediate.
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Arredondo, M., V. Cambiazo, L. Tapia, M. González-Agüero, M. T. Núñez, R. Uauy et M. González. « Copper overload affects copper and iron metabolism in Hep-G2 cells ». American Journal of Physiology-Gastrointestinal and Liver Physiology 287, no 1 (juillet 2004) : G27—G32. http://dx.doi.org/10.1152/ajpgi.00297.2003.
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Divalent metal transporter #1 (DMT1) is responsible for intestinal nonheme Fe apical uptake. However, DMT1 appears to have an additional function in Cu transport in intestinal cells. Because the liver has an essential role in body Cu homeostasis, we examined the potential involvement of Cu in the regulation of DMT1 expression and activity in Hep-G2 cells. Cells exposed to 10 μM Cu exhibited a 22-fold increase in Cu content and a twofold decrease in Fe content compared with cells maintained in 0.4 μM Cu. 64Cu uptake in Cu-deficient Hep-G2 cells showed a twofold decrease in Km compared with cells grown in 10 μM Cu. The decreased Km may represent an adaptive response to Cu deficiency. Cells treated with >50 μM Cu, showed an eightfold increase in cytosolic metallothionein. DMT1 protein decreased (35%), suggesting that intracellular Cu caused a reduction of DMT1 protein levels. Our data indicate that, as a result of Cu overload, Hep-G2 cells reduced their Fe content and their DMT1 protein levels. These findings strongly suggest a relationship between Cu and Fe homeostasis in Hep-G2 cells in which Cu accumulation downregulates DMT1 activity.
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Chan, Sun, David Cryer et Roger I. Price. « Enhancement and Validation of a 3D-Printed Solid Target Holder at a Cyclotron Facility in Perth, Australia ». Instruments 3, no 1 (2 février 2019) : 12. http://dx.doi.org/10.3390/instruments3010012.
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A 3D-printed metal solid target using additive manufacturing process is a cost-effective production solution to complex and intricate target design. The initial proof-of-concept prototype solid target holder was 3D-printed in cast alloy, Al–7Si–0.6Mg (A357). However, given the relatively low thermal conductivity for A357 (max, 160 W/m·K), replication of the solid target holder in sterling silver (SS925) with higher thermal conductivity (max, 361 W/m·K) was investigated. The SS925 target holder enhances the cooling efficiency of the target design, thus achieving higher target current during irradiation. A validation production of 64Cu using the 3D-printed SS925 target holder indicated no loss of enriched 64Ni from proton bombardment above 80 µA, at 11.5 MeV.
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Coward, K. M., A. C. Jones, M. E. Pemble, S. A. Rushworth, L. M. Smith et T. Martin. « Next generation adduct purification techniques for low oxygen content metal alkyls ». Journal of Electronic Materials 29, no 1 (janvier 2000) : 151–55. http://dx.doi.org/10.1007/s11664-000-0111-7.
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Rogowski, Marcin, Tomasz Smoliński, Marta Pyszynska, Marcin Brykała et Andrzej G. Chmielewski. « Studies on hydrometallurgical processes using nuclear techniques to be applied in copper industry. II. Application of radiotracers in copper leaching from flotation tailings ». Nukleonika 63, no 4 (1 décembre 2018) : 131–37. http://dx.doi.org/10.2478/nuka-2018-0016.
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Abstract The use of radiotracers in the present study is intended to replace traditional steps of metal quantitative analysis (solution sampling and instrumental chemical analysis) and to allow real-time measurements of metal concentrations during the leaching process. In this study, 64Cu, an isotope of copper, was selected as a radiotracer. Samples of copper flotation tailings were irradiated in the Maria research reactor (Świerk, Poland) and mixed with an inactive portion of the milled fl otation waste. The leaching process was carried out in a glass reactor, and the radiation spectrum was measured using a gamma spectrometer. The material was then treated using various acids (sulphuric acid, nitric acid, acetic acid, citric acid, and ascorbic acid) in a wide range of their concentrations. Experiments with the radiotracer were conducted in sulphuric and nitric acids. The amount of the leached metal (copper) was calculated on the basis of the peak area ratio in the gamma-ray spectrum of the activated tailings and standard samples. Inductively coupled plasma mass spectrometry (ICP-MS) was also used to analyse the metal content. Maximum recovery of 56% Cu was achieved using 9 M HNO3, whereas the recovery was lowest for ascorbic acid (<1%). Both analytical methods were compared, and the results presented in this paper are in good agreement with radiometric measurements obtained using ICP-MS analysis.
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Li, Yuting, Zhiyong Liu, Tianxing Wang et Shuying Shang. « High-piezoresistive sensitivity of silicone matrix composites with low metal filler content ». Materials Letters 171 (mai 2016) : 252–54. http://dx.doi.org/10.1016/j.matlet.2016.02.093.
Texte intégralThèses sur le sujet "64Cu, low metal content"
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Poniger, S., H. Tochon-Danguy, H. Sachinidis, K. Alt, C. Hagemeyer et A. Scott. « Reducing metal contamination in Cu-64 production ». Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166071.
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Introduction
In the past several years there has been a growing interest in the development of radiopharmaceuticals labeled with metallic radionuclides (Anderson et al. 1999). Of particular interest is the positron emitter Cu-64 (t½ = 12.7 h) for molecular imaging of small molecules as well as peptides and antibodies (Smith 2004). This has led us to the recent implementation of a solid target production facility using commercially available target irradiation station and chemistry modules. Routine production of Cu-64 was achieved with an average production yield of 0.32 mCi/μAh, however purification of Cu-64 has proven to be problematic; with several metallic contaminants compromising subsequent radiolabeling. We report in this work, the step by step procedure which led us to the successful production of low metal contaminant 64Cu with high specific activity and high labeling efficiency.
Material and Methods
Detailed implementation of our solid target was reported earlier (Poniger et al. 2012). A Nirta Solid Target from IBA was coupled to our 18/9 cyclotron using a 2-meter external beam line. A pneumatic solid target transfer system (STTS) designed by TEMA was use to deliver the irradiated target disks to a dedicated hotcell. Modules from IBA (Pinctada metal) were used for electroplating 64Ni onto a Ag disk and for acid dissolution and purification of the irradiated target. Typical irradiation parameters were 14.9 MeV at 35 μA for 5–6 hours with 64Ni plating’s ranging from 10–60 μm thickness at 6–12 mm. Radionuclidic purities were evaluated by gamma spectroscopy and traces of metallic impurities were determined by ICP-MS or ICP-AES. Labeling efficiency was evaluated by measuring the amount of 64Cu uptake per 20 μg of scFv-cage.
Results and Conclusion
Initial 64Cu purifications following the manufacturers recommended method resulted in high levels of Cu, Fe and Zn metal contaminants (see TABLE 1, ID 1). Note that little Ag contamination is observed nevertheless the 64Ni is plated directly on a Ag disk. After several productions, visual inspection of the module quickly revealed that the heater block used for heating the back of the Ag target disk was heavily corroded. Replacing the copper heater block with a PEEK heater block drastically reduced the levels of Cu and Fe contaminants.
Unfortunately unusually high levels of Zn were still observed regardless of the stringent conditions and ultrapure reagents used during the processing (see TABLE 1, ID 5). In our quest for answers, ICP-MS analysis of the 64Ni plating solution as well as critical stock reagents such as Milli-Q water (18 MΩ cm−1) and 30% HCl TraceSelect Ultra (Sigma) was performed (see TABLE 1, ID 2,3,4). The results were surprising, with high level of Zn found not only in the 64Ni plating solution, but as well in the HCl TraceSelect Ultra. It was hypothesized that the Pinctada’s glass bottles (Kay, 2004) used to store the reagents, especially concentrated acidic solutions were the source of Zn contamination and all glass bottles were replaced by LDPE or PFA types. Our hypothesis was confirmed by subsequent ICP-MS analysis of fresh samples of HCl TraceSelect Ultra and the 64Ni plating solution prepared/stored in plastic containers (see TABLE 1, ID 6,7). We also confirmed by ICP-MS analysis that no contamination occurred when performing a non-radioactive dissolution/purification sequence on the Pinctada module using a blank PTFE target disk in conjunction with the change to plastic reagent storage bottles (see TABLE 1, ID 8).
Initially the purification protocol was modified as described by Ometakova et al., 2012 to help reduce the co-elution of Zn contaminants with the 64Cu from the AG1-X8 resin. This change resulted in a significant amount of 64Cu eluting from the resin during the resin washing steps, so that protocol was abandoned and the protocol as described by Thieme et al., 2012 was adopted. By modifying the AG1-X8 resin washing protocol to this new method and eluting the 64Cu from with 0.1M HCl rather than Milli-Q water (see TABLE 1, ID 9), we were able to further reduce metal contaminants, especially Zn.
During the course of these experiments, the true specific activity of 64Cu increased from as low as 12 mCi/μmol of Cu (n = 2, TABLE 1, ID 1) to 649 mCi/μmol of Cu (n = 7, TABLE 1, ID 5) and finally to 4412 mCi/μmol of Cu (n = 3, TABLE 1, ID 9). In the same time, the effective specific activity increased from 0.03 ± 0.02 mCi per 20 μg of scFv-cage, to 3.7 ± 0.3 mCi per 20 g of scFv-cage with 64Cu.
In conclusion, a significant reduction in Cu, Fe and Zn contaminants was achieved when processing 64Cu using the Pinctada module: i) after replacement of the Cu heater block; ii) after elimination of glass reagent storage containers from the Pinctada module and procedures during preparation of the 64Ni plating solution and iii) after implementation of a new purification protocol (Thieme et al. 2012). Introduction of a 6M HCl wash-up cycle of the module prior to the dissolution procedure was also effective. However in recent 64Cu productions slightly elevated Ag levels have been observed and are under investigation (see TABLE 1, ID 9).
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Schön, Anke. « Development of alternative 3-way catalysts : Fe-based perovskites with low noble metal content ». Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10030.
Texte intégralRésumé :
Cette étude vise à développer de nouveaux catalyseurs 3-voies (TWC) pour le traitement de gaz d’échappement issus de moteurs à essence. TWC doivent simultanément éliminer le monoxyde de carbone, les hydrocarbures et les oxydes d’azote (NOx). Le remplacement partiel des métaux nobles (PGM) qui sont actuellement utilisés comme phase active dans les TWC est l’objectif de cette étude. Afin de parvenir à ce but, des perovskites à base de Fe ont été étudiées. L’inconvénient majeur des PGM est leur rareté qui cause un coût élevé d’exploitation et d’usage. La stabilité des nanoparticules ayant tendance de fritter lors de l’usage du TWC et la faible sélectivité en N2 (SN2) pendant la conversion de NO nécessitent une amélioration. Les réactions 3-voies ont été menées sur les perovskites à base de LaFeO3 dans des flux complexes contenant les 3 types de polluants et d’autres gaz naturellement présents comme O2, H2 ainsi que de hautes quantités d’inhibiteurs (CO2, H2O). Afin d’améliorer les résultats de la perovskite LaFeO3, 2 approches – l’optimisation des propriétés texturales et de la composition – ont été poursuivies. Les propriétés texturales ont pu être améliorées par l’optimisation de paramètres de synthèse comme le solvant ou l’atmosphère de calcination. Le changement de l’atmosphère de calcination a donné des résultats prometteurs sur la réduction des NOx. L’optimisation de la composition de la surface et du bulk a apporté un gain significatif en performance catalytique. De plus, une SN2 accrue est observée comparé à un catalyseur de référence commercial. Le dopage à faible teneur en métaux nobles amène à une performance élevée qui a été augmenté par un traitement réducteurThis study aims at developing alternative 3-way catalysts (TWC) for the exhaust gas treatment ofspark-ignition engines. Petrol engine exhaust comprises carbon monoxide, hydrocarbons and nitrogenoxides (NOx) which need to be eliminated simultaneously. The partial replacement of platinum groupmetals (PGM) which are nowadays used as TWC active phase was intended. To this end, Fe-basedperovskites were investigated. The main drawback of PGM is their scarcity which leads to high environmental, societal and economic exploitation and usage cost. The stability of PGM nanoparticles which tend to sinter during catalyst operation and the N2 selectivity during NOx reduction also deserve improvement. 3-way catalytic reactions have been performed on LaFeO3-based perovskites in complex feed streams containing all 3 kinds of pollutants and other naturally present gases such as O2 and H2 and high amounts of inhibitors (CO2, H2O). To improve results of the LaFeO3 perovskite, 2 approaches – textural properties and composition optimisation – were studied. Textural properties could be improved by optimising synthesis parameters such as the employed solvent and the calcination atmosphere. Interesting NOx reduction results were obtained by changing the calcination atmosphere during LaFeO3 synthesis. Surface and bulk composition optimisation lead to significantly enhanced catalytic performances. Furthermore, an increased N2 selectivity is observed compared to a commercial reference catalyst. Thedoping with low PGM content lead to enhanced performances which were increased by a reductivepre-treatment
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Spöri, Camillo Wolfgang [Verfasser], Peter [Akademischer Betreuer] Strasser, Peter [Gutachter] Strasser et Ifan E. L. [Gutachter] Stephens. « Structure-stability-activity studies on low Ir content mixed metal oxides for the electrochemical water oxidation in acidic media / Camillo Wolfgang Spöri ; Gutachter : Peter Strasser, Ifan E.L. Stephens ; Betreuer : Peter Strasser ». Berlin : Technische Universität Berlin, 2019. http://d-nb.info/119125688X/34.
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Schöen, Anke. « Development of alternative 3-way catalysts : Fe-based perovskites with low noble metal content ». Thesis, 2015. http://www.theses.fr/2015LIL10030/document.
Texte intégralRésumé :
Cette étude vise à développer de nouveaux catalyseurs 3-voies (TWC) pour le traitement de gaz d’échappement issus de moteurs à essence. TWC doivent simultanément éliminer le monoxyde de carbone, les hydrocarbures et les oxydes d’azote (NOx). Le remplacement partiel des métaux nobles (PGM) qui sont actuellement utilisés comme phase active dans les TWC est l’objectif de cette étude. Afin de parvenir à ce but, des perovskites à base de Fe ont été étudiées. L’inconvénient majeur des PGM est leur rareté qui cause un coût élevé d’exploitation et d’usage. La stabilité des nanoparticules ayant tendance de fritter lors de l’usage du TWC et la faible sélectivité en N2 (SN2) pendant la conversion de NO nécessitent une amélioration. Les réactions 3-voies ont été menées sur les perovskites à base de LaFeO3 dans des flux complexes contenant les 3 types de polluants et d’autres gaz naturellement présents comme O2, H2 ainsi que de hautes quantités d’inhibiteurs (CO2, H2O). Afin d’améliorer les résultats de la perovskite LaFeO3, 2 approches – l’optimisation des propriétés texturales et de la composition – ont été poursuivies. Les propriétés texturales ont pu être améliorées par l’optimisation de paramètres de synthèse comme le solvant ou l’atmosphère de calcination. Le changement de l’atmosphère de calcination a donné des résultats prometteurs sur la réduction des NOx. L’optimisation de la composition de la surface et du bulk a apporté un gain significatif en performance catalytique. De plus, une SN2 accrue est observée comparé à un catalyseur de référence commercial. Le dopage à faible teneur en métaux nobles amène à une performance élevée qui a été augmenté par un traitement réducteurThis study aims at developing alternative 3-way catalysts (TWC) for the exhaust gas treatment ofspark-ignition engines. Petrol engine exhaust comprises carbon monoxide, hydrocarbons and nitrogenoxides (NOx) which need to be eliminated simultaneously. The partial replacement of platinum groupmetals (PGM) which are nowadays used as TWC active phase was intended. To this end, Fe-basedperovskites were investigated. The main drawback of PGM is their scarcity which leads to high environmental, societal and economic exploitation and usage cost. The stability of PGM nanoparticles which tend to sinter during catalyst operation and the N2 selectivity during NOx reduction also deserve improvement. 3-way catalytic reactions have been performed on LaFeO3-based perovskites in complex feed streams containing all 3 kinds of pollutants and other naturally present gases such as O2 and H2 and high amounts of inhibitors (CO2, H2O). To improve results of the LaFeO3 perovskite, 2 approaches – textural properties and composition optimisation – were studied. Textural properties could be improved by optimising synthesis parameters such as the employed solvent and the calcination atmosphere. Interesting NOx reduction results were obtained by changing the calcination atmosphere during LaFeO3 synthesis. Surface and bulk composition optimisation lead to significantly enhanced catalytic performances. Furthermore, an increased N2 selectivity is observed compared to a commercial reference catalyst. Thedoping with low PGM content lead to enhanced performances which were increased by a reductivepre-treatment
Chapitres de livres sur le sujet "64Cu, low metal content"
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Korovessis, Panagiotis, Thomas Repantis, Panagiotis Aroukatos et Maria Repanti. « Immunological Adverse Reaction Associated with Low Carbide Content Metal-on-Metal Bearings in a Contemporary Cementless Total Hip Arthroplasty ». Dans Total Hip Arthroplasty, 113–23. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-27361-2_10.
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Pal, Raikamal. « Ricinus communis ». Dans Recent Advancements in Bioremediation of Metal Contaminants, 147–64. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-4888-2.ch008.
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Contamination of soil and ground water with heavy metals is a great threat to human health, vegetation, and wildlife. Pb is the second most hazardous substance according to ATSDR. The main sources of Pb entering an ecosystem are atmospheric Pb (mainly from automobile emission), paint chips, fertilizers, and pesticides and Pb acid batteries or other industrial Pb products. Phytoremediation could provide sustainable techniques for metal remediation. Roots of Ricinus communis were found to accumulate maximum amount of Pb (275.12mg/kg dry wt,). Depending on soil Pb content, the concentration of Pb in shoots of Ricinus communis also varied. In most cases only a small part of Pb was translocated in the aerial parts. In 95% of the plant samples collected, the root Pb concentration are much greater than those of the shoot lead content, indicating low mobility of Pb from roots to the shoots. Their ability to accumulate higher amounts of Pb in their roots and considering their rapid growth rate and biomass, this plant has the potential for removal of Pb from contaminated soil.
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Kouass, Salah, Amor Fadhalaoui, Hassouna Dhaouadi et Fathi Touati. « Designing and Synthesis of (Cd2+, Li+), Cr3+, Bi3+ Doped CePO4 Materials Optical, Electrochemical, Ionic Conductivity Analysis ». Dans Electrochemical Impedance Spectroscopy. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.91330.
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Most of the work has been done on the optical properties of the rare earth doped CePO4, so there are few studies on the effect of metal ion doping on CePO4. The doping improves the properties of the compounds and can lead to new properties. It is the first time, that multi- ionic doping process is used in the CePO4matrix, in order to improve the ionic conductivity and the electrochemical stability. The low percentage of (Cd2+, Li+), Cr3+, Bi3+ dopant affect the structure showing a weak decrease in the lattice parameters compared to the CePO4. Impedance spectroscopy analysis was used to analyze the electrical behavior of samples as a function of frequency at different temperatures. The total electrical conductivity plots obtained from impedance spectra shows an increase of the total conductivity as Li, Cr-content increases. The determined energy gap values decrease with increasingly Li+, Cr3+ and Bi3+ doping content. Electrochemical tests showed an improved capacity when increasing the Li+, Cr3+ and Bi3+ content and a stable cycling performance.
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Dembaremba, Tendai O., Adeniyi S. Ogunlaja et Zenixole R. Tshentu. « Coordination Polymers and Polymer Nanofibers for Effective Adsorptive Desulfurization ». Dans Nanocomposites for the Desulfurization of Fuels, 168–234. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-2146-5.ch006.
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Desulfurization of fuel oils is an essential process employed in petroleum refineries to reduce the sulfur content to levels mandated for environmental protection. Hydrodesulfurization (HDS), which is currently being employed, is limited in treating refractory organosulfur compounds and only reduces the sulfur content in fuels to a range of 200-500 ppmS. In this chapter, several scientific and technological advances reported in the literature for the desulfurization of fuels are reviewed and discussed. Amongst these techniques, oxidative desulfurization (ODS) and adsorptive desulfurization (ADS) are proposed as additional steps to complement HDS in meeting the mandated ultra-low sulfur levels (10 ppmS). In the ODS technique, refractory organosulfur compounds are oxidized to organosulfones, followed by solvent extraction or adsorption of the organosulfones. The chemistry involved in the development and fabrication of sulfur/sulfone responsive adsorbents is also discussed. The use of molecular imprinted polymers (MIPs) and coordination polymers (CPs) for the selective adsorption of organosulfone compounds (in ODS) and/or organosulfur (in ADS) offers various properties such as imprinting effect, hydrogen bonding, π-π interactions, van der Waals forces, π-complexation, and electrostatic interactions. CPs, in particular metal organic frameworks (MOFs), have been reported to possess suitable features to overcome most of these challenges associated with adsorptive ultra-deep desulfurization when design strategies to achieve good selectivity are strictly followed. Matching the sizes of the cavities to the critical dimensions of the sulfur containing compounds (SCCs), using suitable metal centres which allow for coordinative interaction with the SCCs and using linkers with suitable functionality as to enhance specific interaction (dispersion forces) with the SCCs were considered to be pivotal features to prioritize. The prospects for the use of MIPs and CPs for future industrial applications in desulfurization are envisaged.
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Dembaremba, Tendai O., Adeniyi S. Ogunlaja et Zenixole R. Tshentu. « Coordination Polymers and Polymer Nanofibers for Effective Adsorptive Desulfurization ». Dans Research Anthology on Synthesis, Characterization, and Applications of Nanomaterials, 730–83. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8591-7.ch032.
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Desulfurization of fuel oils is an essential process employed in petroleum refineries to reduce the sulfur content to levels mandated for environmental protection. Hydrodesulfurization (HDS), which is currently being employed, is limited in treating refractory organosulfur compounds and only reduces the sulfur content in fuels to a range of 200-500 ppmS. In this chapter, several scientific and technological advances reported in the literature for the desulfurization of fuels are reviewed and discussed. Amongst these techniques, oxidative desulfurization (ODS) and adsorptive desulfurization (ADS) are proposed as additional steps to complement HDS in meeting the mandated ultra-low sulfur levels (10 ppmS). In the ODS technique, refractory organosulfur compounds are oxidized to organosulfones, followed by solvent extraction or adsorption of the organosulfones. The chemistry involved in the development and fabrication of sulfur/sulfone responsive adsorbents is also discussed. The use of molecular imprinted polymers (MIPs) and coordination polymers (CPs) for the selective adsorption of organosulfone compounds (in ODS) and/or organosulfur (in ADS) offers various properties such as imprinting effect, hydrogen bonding, π-π interactions, van der Waals forces, π-complexation, and electrostatic interactions. CPs, in particular metal organic frameworks (MOFs), have been reported to possess suitable features to overcome most of these challenges associated with adsorptive ultra-deep desulfurization when design strategies to achieve good selectivity are strictly followed. Matching the sizes of the cavities to the critical dimensions of the sulfur containing compounds (SCCs), using suitable metal centres which allow for coordinative interaction with the SCCs and using linkers with suitable functionality as to enhance specific interaction (dispersion forces) with the SCCs were considered to be pivotal features to prioritize. The prospects for the use of MIPs and CPs for future industrial applications in desulfurization are envisaged.
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Bethke, Craig M. « Acid Drainage ». Dans Geochemical Reaction Modeling. Oxford University Press, 1996. http://dx.doi.org/10.1093/oso/9780195094756.003.0027.
Texte intégralRésumé :
Acid drainage is a persistent environmental problem in many mineralized areas. The problem is especially pronounced in areas that host or have hosted mining activity (e.g., Lind and Hem, 1993), but it also occurs naturally in unmined areas. The acid drainage results from the weathering of sulfide minerals that oxidize to produce hydrogen ions and contribute dissolved metals to solution. These acidic waters are toxic to plant and animal life, including fish and aquatic insects. Streams affected by acid drainage may be rendered nearly lifeless, their stream beds coated with unsightly yellow and red precipitates of oxy-hydroxide minerals. In some cases, the heavy metals in acid drainage threaten water supplies and irrigation projects. Where acid drainage is well developed and extensive, the costs of remediation can be high. In the Summitville, Colorado district (USA), for example, efforts to limit the contamination of fertile irrigated farmlands in the nearby San Luis Valley and protect aquatic life in the Alamosa River will cost an estimated $100 million or more (Plumlee, 1994a). Not all mine drainage, however, is acidic or rich in dissolved metals (e.g., Ficklin et al., 1992; Mayo et al., 1992; Plumlee et al., 1992). Drainage from mining districts in the Colorado Mineral Belt ranges in pH from 1.7 to greater than 8 and contains total metal concentrations ranging from as low as about 0.1 mg/kg to more than 1000 mg/kg. The primary controls on drainage pH and metal content seem to be (1) the exposure of sulfide minerals to weathering, (2) the availability of atmospheric oxygen, and (3) the ability of nonsulfide minerals to buffer acidity. In this chapter we construct geochemical models to consider how the availability of oxygen and the buffering of host rocks affect the pH and composition of acid drainage. We then look at processes that can attenuate the dissolved metal content of drainage waters. Acid drainage results from the reaction of sulfide minerals with oxygen in the presence of water. As we show in this section, water in the absence of a supply of oxygen gas becomes saturated with respect to a sulfide mineral after only a small amount of the mineral has dissolved.
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Evans, Hugh L. « Cognitive and Behavioral Manifestations of Lead ». Dans Cognitive and Behavioral Abnormalities of Pediatric Diseases. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195342680.003.0071.
Texte intégralRésumé :
The link between exposure to lead and children’s cognitive problems was implied in the earliest medical reports of frank lead poisoning of young children in Australia in the 1800s (Lin-Fu 1992). Children with acute severe toxicity of lead (Pb) are now rarely seen in the United States. However, millions of children may have subclinical neurobehavioral disorders associated with chronic low-level exposure to lead, representing a major public health concern (Bellinger 2008a). Lead is a nonessential metal that is recognized as a source of toxic exposure, with the developing nervous system particularly vulnerable. Because of this, U.S. regulations limiting the lead content of gasoline and household paint have led to a gradual reduction of the average blood lead concentration of Americans over the last three decades. Average blood lead levels of children in the United States dropped an estimated 78% from 1976 to 1991 (Brody et al. 1994; Caldwell et al. 2009). Despite these reductions in exposure to lead, new advances in research techniques have documented harmful consequences associated with lower blood lead levels. This raises the possibility that there is no threshold for occurrence of lead-induced toxicity. Bellinger (2008a) refers to “the silent pandemic of neurodevelopmental disorders resulting from children’s continuing exposure to low levels of lead.” The developing brain may be more sensitive to exposure to lead than the adult. Since the pioneering work of Needleman and colleagues (1979), a large scientific literature has documented the deleterious effects of pre- and neonatal exposure to lead. Decrements in IQ scores have proven to be among the most sensitive and consistent consequences of a child’s exposure to lead, but other cognitive and behavioral changes have been described as well, including attention-deficit hyperactivity disorder (ADHD). Among the important current sources of children’s exposure to lead is household dust (Dixon et al. 2009) the lead content in old water pipes, batteries, and from contamination by numerous industrial processes. Pre and postnatal exposure to cigarette smoke is a cofactor with lead exposure in children’s conduct disorders (Braun et al. 2008). Diagnosis of lead-induced disorders involves the determination of exposure to lead and the atomic absorption assay of lead in whole blood.
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Florin Danet, Andrei. « Recent Advances in Antioxidant Capacity Assays ». Dans Antioxidants - Benefits, Sources, Mechanisms of Action. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96654.
Texte intégralRésumé :
This work presents a survey of the important antioxidant capacity/activity assays applied for a diversity of samples including plant extracts, foods, biological material, etc. The published materials are critically discussed, emphasizing the recent findings in the field. New and emergent antioxidant capacity assays, such as nanoparticles-based assay, are also presented. The discussion includes chemical-based methods as well as biochemical and cellular assays. Chemical methods detailed are radical/ROS-based scavenging assays (the trolox equivalent antioxidant capacity (TEAC/ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical absorbance capacity (ORAC) assays, chemiluminescence methods, total radical-trapping antioxidant parameter (TRAP), total oxy radical scavenging capacity (TOSC), and β-carotene bleaching assays), non-radical redox potential-based assays (ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), nanoparticle-based methods and electrochemical methods), metal chelation capacity and total phenolic content tests. The biochemical-based assays and in vivo assays discussed include the oxidation of low density lipoprotein (LDL), the thiobarbituric acid reactive substances (TBARS) and the cellular antioxidant activity (CAA) assays. While a direct link between the antioxidant capacity and health benefits is still a matter of debate, the antioxidant testing methodologies presented in this chapter remain valuable for the high efficiency and cost-effective evaluation of antioxidants, from compound discovery to quality control.
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Schilsky, Michael L., et Pramod K. Mistry. « Inherited diseases of copper metabolism : Wilson’s disease and Menkes’ disease ». Dans Oxford Textbook of Medicine, sous la direction de Timothy M. Cox, 2115–20. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198746690.003.0234.
Texte intégralRésumé :
Copper is an essential metal that is an important cofactor for many proteins and enzymes. Two related genetic defects in copper transport have been described, each with distinct phenotypes. Wilson’s disease—an uncommon disorder (1 in 30 000) caused by autosomal recessive loss-of-function mutations in a metal-transporting P-type ATPase (ATP7B) that result in defective copper excretion into bile and hence copper toxicity. Typical presentation is in the second and third decade of life with liver disease (ranging from asymptomatic to acute fulminant hepatic failure or chronic end-stage liver disease) or neurological or psychiatric disorder (dystonia, dysarthria, parkinsonian tremor, movement disorder, a spectrum of psychiatric ailments). While no single biochemical test or clinical finding is sufficient for establishing the diagnosis, typical findings include low serum ceruloplasmin, high urinary copper excretion, and elevated liver copper content. Corneal Kayser–Fleischer rings may be seen. Treatment is with copper chelating agents and zinc. Liver transplantation is required for fulminant hepatic failure and decompensated liver disease unresponsive to medical therapy. Menkes’ disease—a rare disorder (1 in 300 000) caused by X-linked loss-of-function mutations in a P-type ATPase homologous to ATP7B (ATP7A) that result in defective copper transport across intestine, placenta, and brain and hence cellular copper deficiency. Clinical presentation is in infancy with facial dimorphism, connective tissue disorder, hypopigmentation, abnormal hair, seizures, and failure to thrive, usually followed by death by age 3 years (although some variants with a milder phenotype result from milder mutations, e.g. occipital horn syndrome). Treatment, which is only effective when presymptomatic diagnosis is made in a sibling after florid presentation in a previous affected sibling, is with intravenous copper histidine.
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Wang, J. H. « Lime Potential ». Dans Chemistry of Variable Charge Soils. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195097450.003.0015.
Texte intégralRésumé :
The properties of hydrogen and aluminum ions have been examined in Chapters 10 and 11. These two ion species are ions that directly induce the acid reaction in soils. In soils devoid of soluble salts, the content of cations is constant and the negative surface charges are saturated by, besides hydrogen and aluminum ions, alkali metal and alkaline earth metal ions. These ions are called base ions. The acidity of a soil is determined chiefly by the ratio of the quantity of hydrogen and aluminum ions to that of base ions. Among these base ions, calcium ions occupy the most important position, because they generally account for 65-80% of the total amount of base ions in variable charge soils. Therefore, calcium is an ion species closely related to the acidity of soils. In addition to the parameter pH that directly reflects the concentration of hydrogen ions, one other desirable way is to find a parameter that can reflect the ratio of the hydrogen ions to the calcium ions. This parameter is the lime potential. Since the introduction of the concept of lime potential 40 years ago, little practical application has been made in soil science, although some further theoretical considerations were advanced in the 1950s and the 1960s. Actually, as shall be seen in this chapter, for strongly acid soils, such as variable charge soils, because the quantity of hydrogen ions is too high and at the same time the quantity of calcium ions is too low, lime potential that can reflect the relative ratio of these two ion species is of significance not only in theory but also in practice. The mathematical expression of lime potential is pH-0.5pCa. Lime potential is a simple function of the chemical potential of calcium hydroxide, lime. Hence it may be called lime potential. The physical meaning of pH-0.5pCa can be derived as follows.
Actes de conférences sur le sujet "64Cu, low metal content"
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NYO, Tun Tun, Antti KAIJALAINEN, Jaakko HANNULA, Mahesh SOMANI et Jukka KÖMI. « Influence of Chromium content on the mechanical properties and HAZ simulations of Low-Carbon Bainitic Steels ». Dans METAL 2019. TANGER Ltd., 2019. http://dx.doi.org/10.37904/metal.2019.712.
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Nelson, Carl V., et Toan B. Huynh. « Spatial scanning time-domain electromagnetic sensor : high spatial and time resolution signatures from metal targets and low-metal content land mines ». Dans AeroSense 2002, sous la direction de J. Thomas Broach, Russell S. Harmon et Gerald J. Dobeck. SPIE, 2002. http://dx.doi.org/10.1117/12.479150.
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Nelson, Blaine A., Deborah Schofield et Leslie M. Collins. « A comparison of neural networks and subspace detectors for the discrimination of low-metal-content landmines ». Dans AeroSense 2003, sous la direction de Russell S. Harmon, John H. Holloway, Jr. et J. T. Broach. SPIE, 2003. http://dx.doi.org/10.1117/12.487220.
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Pristipa, K. V., T. A. Kukulyanskaya et E. A. Khramtsova. « The content of low molecular weight antioxidants in transgenic plants Nicotiana tabacum under heavy metal salts conditions ». Dans 2nd International Scientific Conference "Plants and Microbes : the Future of Biotechnology". PLAMIC2020 Organizing committee, 2020. http://dx.doi.org/10.28983/plamic2020.199.
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We were studied several of antioxidants in transgenic Nicotiana tabacum, plants cultivated in heavy metal polluted soils. The content of phenolic compounds, vitamins C and E in plants increased under these conditions.
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Cameron, Kimberly K., et Alfred M. Pettinger. « The Effect of Low Sulfur Content on the Weldability of Linepipe Steel ». Dans 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90488.
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Over time, the demand for high-strength linepipe has increased significantly. One of the challenges for developing higher strength linepipe has been maintaining an appropriate level of fracture toughness, yield to tensile strength ratio, and weldability. Fortunately, significant progress has been made in the production of high strength line pipe steel. A major improvement in steel making has been the utilization of secondary steel treatments to refine the steel and accurately control alloy additions to achieve a higher level of steel cleanliness. In particular, these refining treatments have enabled the achievement of extremely low sulfur levels. For most purposes, restricting sulfur content is desirable to help prevent a reduction in mechanical properties such as fracture toughness of the steel. Fortunately, steelmaking and desulfurization technologies have advanced to the point where pipeline steel with sulfur contents less than the requirements by API 5L are available on a large scale. Extremely low sulfur contents, however, can lead to other problems when welding steels. These weldability problems are related to the fact that sulfur is a known surface active agent for steels. Low sulfur concentrations lead to a reversal of the Marangoni convection in the weld pool, which is responsible for the large differences in weld penetration on otherwise identical steels. Additionally, when welding heats of unmatched sulfur concentrations, the arc will tend to deviate towards the low sulfur heat and axially shift the root of the weld if one of the heats was below a critical value for the sulfur content and the other was above this value. Although this phenomenon has been primarily observed in stainless steels, the increasing ability to produce linepipe steel with extremely low sulfur contents has led to the possibility that this phenomenon could also occur in low carbon pipeline steels. One pipeline system utilizing cellulosic consumables for shielded metal arc welding (SMAW) of X70 steel with sulfur contents an order of magnitude below that permitted by API 5L and with widely varying sulfur contents shows evidence of this effect. The profiles of the welds in this system exhibited a tendency for lack of penetration, asymmetric weld roots, and concave welds. One approach to ameliorate this would be the specification of a lower permissible amount of sulfur.
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Turhan-Sayan, Gönül, Mesut Dogan et Omer Yesilyurt. « Inside-the-wall detection of objects with low metal content using the GPR sensor : effects of different wall structures on the detection performance ». Dans Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XXIII, sous la direction de Jason C. Isaacs et Steven S. Bishop. SPIE, 2018. http://dx.doi.org/10.1117/12.2304611.
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Nakano, Masakatsu, Tomohiro Tanaka, Masamitsu Abe, Mitsuyoshi Nakatani et Hidenori Terasaki. « Improvement of Low-Temperature Toughness in Weld Metal Made of 9Cr-1Mo-V Steel by GTAW Method ». Dans ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93466.
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Abstract Energy demand will increase due to global population growth in the future. As one of solutions for the demand, it will be necessary to operate petroleum service plants more efficiently. To improve refining efficiency, operation at higher temperatures is required of reactors used in high-pressure hydrogen service at the plants. 9Cr-1Mo-V steel has excellent creep strength compared to 2 1/4Cr-1Mo steel and 2 1/4Cr-1Mo-V steel, which have been conventionally applied to reactors, and has been already put into commercial use for boilers of thermal power plants, etc. Further application of 9Cr-1Mo-V steel is expected for reactors at petroleum refining plants. As materials applied to reactors, low-temperature toughness should be considered for weld joints in addition to creep strength. However, 9Cr-1Mo-V steel has poor low-temperature toughness compared to 2 1/4Cr-1Mo steel and 2 1/4Cr-1Mo-V steel. As for the welding methods applied to reactors, Submerged Arc Welding (SAW), Shielded Metal Arc Welding (SMAW), and Gas Tungsten Arc Welding (GTAW) can be used. The 9Cr-1Mo-V steel weld metals formed by SAW and SMAW have a high oxygen content, and their low-temperature toughness is inferior to that of the weld metal formed by GTAW. On the other hand, the GTAW weld metal has a low oxygen content and excellent low-temperature toughness. Therefore, GTAW is an effective way to improve the toughness of the weld metal. However, GTAW has low productivity compared with others, so it is necessary to apply to a narrow groove and a hot wire method to improve the productivity. In this paper, the application of narrow gap GTAW using the hot wire method was considered for welding of 9Cr-1Mo-V steel. When using the hot wire method, productivity of GTAW increases in comparison to the conventional method, leading to increased weld pass thickness. With the increase in pass thickness, the area of coarse grains increases because of decreasing thermal effect by the subsequent pass, then the low-temperature toughness decreases. Therefore, in order to improve the low-temperature toughness by refining the grains of the GTAW weld metal, the melt-run method, arc re-melting without adding fillers, was conducted after the former weld pass metal solidified. The weld metal from the melt-run method had finer grains compared with those of the weld metal without the melt-run method, and the low-temperature toughness increased. On the other hand, the melt-run method requires two processes: welding and melt-run. Therefore, a tandem electrode GTAW machine was produced in which an electrode for welding and the other one for melt-run were placed continuously to make it possible to execute welding and a melt-run without a time lag. As a result, it is possible to manufacture reactors made of 9Cr-1Mo-V steel for petroleum refining plants with sufficient low-temperature toughness by applying a welding method with narrow gap GTAW and a melt-run method combined.
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Honma, Yuta, Rinzo Kayano, Mikihiro Sakata et Ken Yamashita. « Existence Form of Boron in Dissimilar Weld Metals of Low Alloy Steel With Boron Bearing High Chromium Steel ». Dans ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97253.
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Recently, boron bearing high chromium steel is applied to structural material of a fossil power generation plant. Dissimilar weld joints between this steel and low alloy steel are applied for various parts such as boiler or other equipments in this plant. In this weld joint, boron added to low alloy steel weld metals by the dilution from boron bearing base metal. However, the existence form of boron and the effect of boron on reheat cracking susceptibility during post weld heat treatment (PWHT) have not been surveyed in previous literature. So, reheat cracking test, precipitated carbide observation of boron bearing Cr-Mo low alloy steel weld metal was carried out in this study. From these test results, the reheat cracking susceptibility clearly increased by boron addition. Moreover, it decreased according to increasing chromium content. It was estimated that the structural form of boron was recognized in four kinds, such as BN, M2B, M23(C,B)6 and dissolved boron by thermo-dynamic calculation. The amount of M23C6 type carbide was increased with increasing chromium content. On the basis of these results, it was presumed that large amounts of dissolved boron existed in boron bearing low chromium steel weld metal compared with high chromium one during PWHT.
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Silva, Fernando F., Fabio Arroyo, Philippe Darcis, Marcelo Fritz, Marcelo Salani et Adriano Silva. « Advanced SAWL Developments and Optimizations for High Toughness, Low Hardness and Sour Environment ». Dans 2018 12th International Pipeline Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/ipc2018-78108.
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Natural gas exploitation has been increasing progressively and the pipeline community are facing more challenging demands to ensure safe and reliable operations. In that direction, gas fields in very harsh environments are demanding material and welding procedure selections to comply with a combination of important requirements such as toughness at low temperature, sour environment, very low hardness, manual ultrasonic inspection (for UOE longitudinal weld soundness assurance) and others. Looking forwarding big challenges, Tenaris Confab has been successfully working to continue improving the know how regarding plate to pipe mechanical properties behavior, through steel selection using TMCP plates, welding consumables definition and process control to assure material performance. Considering this scenario, the main challenge is to comply with a combination of toughness and hardness requirements, assuring the material soundness through manual ultrasonic testing after 48h. These combination lead to a careful selection of welding consumable to add the right content of alloy element at the welding pool aiming a specific weld metal chemical composition after dilution. The alloy element selection has to be considered due to the aimed final microstructure at the weld metal, i.e. increases acicular ferrite, in order to achieve the toughness, hardness and manual ultrasonic performance for delayed hydrogen cracking (DHC); it is important to avoid grain boundary ferrite (GBF) nucleation. High wall thickness and high heat input increases residual stress after pipe welding, high residual stress combined to poor microstructure and hydrogen, is a perfect scenario for DHC. To avoid hydrogen cracks, a robust pipe forming process and welding concept is needed to give enough energy to diffuse hydrogen out from weld metal. Quality controls were applied to strict hydrogen content such as welding consumable specifications, evaluating the correlation curve between flux moisture and diffusible hydrogen, flux temperature control and others. As a result of those actions, good mechanical properties were achieved and overcoming the hydrogen cracking performance during automatic and manual ultrasonic testing confirm a robust pipe forming and welding procedure for demanding projects.
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Almostaneer, Hamad H., Stephen Liu et David L. Olson. « Characterizing Metal Arc Welding Under Oil (MAW-UO) ». Dans ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50286.
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Metal arc welding under oil (MAW-UO) is a new, revolutionary process for the repair of pipelines without the need of hot tapping and constructing bypass lines. The process uses an automated metal arc welding setup with a continuous wire feed. This process was developed for in-situ internal repairs of in-service cross-country pipelines, tanks and vessels by using a smart-pig with a modified mechanical design that allows for welding. Since some of the cross-country pipeline segments are either buried or under highways making access difficult, the new process will provide great flexibility to the repair of these pipelines. In this paper, the development of the MAW-UO process is described. Process parameters that successfully produced weldments are identified and the consumables tested are reported and discussed. The unique characteristics found in the under oil welds will be discussed in detail and related to the processing parameters and the oil environment. Welding is possible under oil because of the vaporization of the oil to form an oil vapor bubble that surrounds the welding arc plasma and protects the molten steel weld pool. Contrary to general belief, oil does not combust in the presence of a welding arc. The low oxygen content within the oil itself and the low diffusivity of oxygen within the oil even at elevated temperatures are the two main factors that prevent oil combustion during welding. Decomposition of the oil and the decomposed products are expected to significantly affect the weld metal composition and microstructure.
Rapports d'organisations sur le sujet "64Cu, low metal content"
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Wang, Jia X., et Michael Furey. Low Noble Metal Content Catalysts/Electrodes for Hydrogen Production by Water Electrolysis. Office of Scientific and Technical Information (OSTI), novembre 2013. http://dx.doi.org/10.2172/1104660.
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Wang, Jia. Low Noble Metal Content Catalysts/Electrodes for Hydrogen Production by Water Electrolysis. Office of Scientific and Technical Information (OSTI), août 2015. http://dx.doi.org/10.2172/1466639.
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Busby, Ryan, Thomas Douglas, Joshua LeMonte, David Ringelberg et Karl Indest. Metal accumulation capacity in indigenous Alaska vegetation growing on military training lands. Engineer Research and Development Center (U.S.), août 2021. http://dx.doi.org/10.21079/11681/41443.
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Permafrost thawing could increase soil contaminant mobilization in the environment. Our objective was to quantify metal accumulation capacities for plant species and functional groups common to Alaskan military training ranges where elevated soil metal concentrations were likely to occur. Plant species across multiple military training range sites were collected. Metal content in shoots and roots was compared to soil metal concentrations to calculate bioconcentration and translocation factors. On average, grasses accumulated greater concentrations of Cr, Cu, Ni, Pb, Sb, and Zn relative to forbs or shrubs, and bioconcentrated greater concentrations of Ni and Pb. Shrubs bioconcentrated greater concentrations of Sb. Translocation to shoots was greatest among the forbs. Three native plants were identified as candidate species for use in metal phytostabilization applications. Elymus macrourus, a grass, bioconcentrated substantial concentrations of Cu, Pb, and Zn in roots with low translocation to shoots. Elaeagnus commutata, a shrub, bioconcentrated the greatest amounts of Sb, Ni, and Cr, with a low translocation factor. Solidago decumbens bio-concentrated the greatest amount of Sb among the forbs and translocated the least amount of metals. A combination of forb, shrub, and grass will likely enhance phytostabilization of heavy metals in interior Alaska soils through increased functional group diversity.
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Akinleye, Taiwo, Idil Deniz Akin, Amanda Hohner, Indranil Chowdhury, Richards Watts, Xianming Shi, Brendan Dutmer, James Mueller et Will Moody. Evaluation of Electrochemical Treatment for Removal of Arsenic and Manganese from Field Soil. Illinois Center for Transportation, juin 2021. http://dx.doi.org/10.36501/0197-9191/21-019.
Texte intégralRésumé :
Soils containing inorganic compounds are frequently encountered by transportation agencies during construction within the right-of-way, and they pose a threat to human health and the environment. As a result, construction activities may experience project delays and increased costs associated with management of inorganic compounds containing soils required to meet environmental regulations. Recalcitrance of metal-contaminated soils toward conventional treatment technologies is exacerbated in clay or organic content-rich fine-grained soils with low permeability and high sorption capacity because of increased treatment complexity, cost, and duration. The objective of this study was to develop an accelerated in situ electrochemical treatment approach to extract inorganic compounds from fine-grained soils, with the treatment time comparable to excavation and off-site disposal. Three reactor experiments were conducted on samples collected from two borehole locations from a field site in Illinois that contained arsenic (As)(~7.4 mg/kg) and manganese (Mn)(~700 mg/kg). A combination of hydrogen peroxide (H2O2) and/or citrate buffer solution was used to treat the soils. A low-intensity electrical field was applied to soil samples using a bench-scale reactor that resembles field-scale in situ electrochemical systems. For the treatment using 10% H2O2 and citrate buffer solution, average removal of 23% and 8% were achieved for Mn and As, respectively. With 4% H2O2 and citrate buffer, 39% and 24% removal were achieved for Mn and As; while using only citrate buffer as the electrolyte, 49% and 9% removal were achieved for Mn and As, respectively. All chemical regimes adopted in this study reduced the inorganic compound concentrations to below the maximum allowable concentration for Illinois as specified by the Illinois Environmental Protection Agency. The results from this work indicate that electrochemical systems that leverage low concentrations of hydrogen peroxide and citrate buffer can be effective for remediating soils containing manganese and arsenic.