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Artigos de revistas sobre o assunto "Natural nacre"
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Yin, Z., F. Hannard e F. Barthelat. "Impact-resistant nacre-like transparent materials". Science 364, n.º 6447 (27 de junho de 2019): 1260–63. http://dx.doi.org/10.1126/science.aaw8988.
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Glass has outstanding optical properties, hardness, and durability, but its applications are limited by its inherent brittleness and poor impact resistance. Lamination and tempering can improve impact response but do not suppress brittleness. We propose a bioinspired laminated glass that duplicates the three-dimensional “brick-and-mortar” arrangement of nacre from mollusk shells, with periodic three-dimensional architectures and interlayers made of a transparent thermoplastic elastomer. This material reproduces the “tablet sliding mechanism,” which is key to the toughness of natural nacre but has been largely absent in synthetic nacres. Tablet sliding generates nonlinear deformations over large volumes and significantly improves toughness. This nacre-like glass is also two to three times more impact resistant than laminated glass and tempered glass while maintaining high strength and stiffness.
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Vasiliu, Ana. "Natural Pearls". Key Engineering Materials 672 (janeiro de 2016): 80–102. http://dx.doi.org/10.4028/www.scientific.net/kem.672.80.
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A literature less traveled – peaking between 1900-1920 – draws on pre-classical concepts of crystal growth and a trove of field biology, to understand ectopic shell production, the natural source of pearls. By 1907, grafts from the calcifying mantle epithelium on gonads induced nacre mineralization consistently in Pinctada margaritifera, suggesting that anomalously displaced, readily specialized cells are at least a sufficient cause of natural pearl formation. Otherwise, the epithelial sacks wrapping natural nacreous pearls must specialize for nacre production independently from the shell producing mantle – an idea supported by experiments with shell regeneration, but not amenable to a method of inducing pearl formation. At the time, chasing epithelial cell migration was technically unfeasible, signalling was news, stemness was fiction. Boldly, Jameson & Rubbel [1902-1912] marshalled natural pearl nuclei and shell repairs as mineral records of cells specializing de novo into the shell’s secretory regimes. Much of this paper reenacts the historic debate on the origin of pearls: thence bold ideas connect smoothly with new work both on bone or shell. I replicate Jameson’s choice of samples and revisit his proposal to search for an “agency [other than the] shell-secreting mechanism“ acting on ”replacement cells” as the origin of pearls. Much has changed: specialized epithelial cells reportedly migrate; non-differentiated cells remain available throughout and near the calcifying mantle epithelium – both, open possibilities for natural pearl nucleation. Interest in understanding the latter now connects with results sketching the signalling cascade in cell specialization toward bone morphogenesis. Replicating Jameson’s choice of samples, I describe the more spectacular structural changes in the mineralization of pearls associated with two instances of cell specialization: toward producing one shell material – in the event of natural pearl nucleation, or switching between two in later pearl growth. Clusters of cells producing distinctly novel mineralization – nacre over fibrous-prismatic aragonite – could be singled out next to natural pearls by Jameson. The possibility has not been probed in roughly a hundred years. Natural pearl nucleation as a cellular event has never been explored.
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Rousseau, Marthe, Xavier Bourrat, Philippe Stempflé, Marcel Brendlé e Evelyne Lopez. "Multi-Scale Structure of the Pinctada Mother of Pearl: Demonstration of a Continuous and Oriented Organic Framework in a Natural Ceramic". Key Engineering Materials 284-286 (abril de 2005): 705–8. http://dx.doi.org/10.4028/www.scientific.net/kem.284-286.705.
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Sheet nacre is a promising natural bioceramic, which consists on the internal lustrous “mother of pearl” layer of many molluscan shells, e.g. Pinctada, our model. The aim of this work is to study the structure of the flat polygonal tablets of nacre, in order to understand the multi-scale organization of this composite material and the role of the organic template during the growth of the biocrystal. We studied the organic matrix, in situ with techniques such as darkfield transmission electronic microscopy (TEM) on small cross-sections of nacre of Pinctada maxima, or intermittent-contact atomic force microscopy coupled with phase imaging on samples of nacre of Pinctada margaritifera polished parallel to the surface of the tablets. In this study, we demonstrate the continuity of the organic framework and the crystallographic orientation in the biocrystal at 2 relevant levels : nano- and micro-scale.
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Wang, Jiaen, Tianliang Song, Huaxiang Chen, Wei Ming, Zhiming Cheng, Jingwen Liu, Benliang Liang, Yuting Wang e Guangsheng Wang. "Bioinspired High-Strength Montmorillonite-Alginate Hybrid Film: The Effect of Different Divalent Metal Cation Crosslinking". Polymers 14, n.º 12 (16 de junho de 2022): 2433. http://dx.doi.org/10.3390/polym14122433.
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The natural nacre has a regular ordered layered structure of calcium carbonate tablets and ion crosslinking proteins stacked alternately, showing outstanding mechanical properties. Inspired by nacre, we fabricated different divalent metal cation-crosslinked montmorillonite-alginate hybrid films (MMT-ALG-X2+; X2+ = Cu2+, Cd2+, Ba2+, Ca2+, Ni2+, Co2+ or Mn2+). The effect of ionic crosslinking strength and hydrogen bond interaction on the mechanical properties of the nacre-mimetics was studied. With the cations affinities with ALG being increased (Mn2+ < Co2+ = Ni2+ < Ca2+ < Ba2+ < Cd2+ < Cu2+), the tensile strength of nacre-mimetics showed two opposite influence trends: Weak ionic crosslinking (Mn2+, Co2+, Ni2+ and Ca2+) can synergize with hydrogen bonds to greatly increase the tensile properties of the sample; Strong ionic crosslinking (Ba2+, Cd2+, Cu2+) and hydrogen bonding form a competitive relationship, resulting in a rapid decrease in mechanical properties. Mn2+ crosslinking generates optimal strength of 288.0 ± 15.2 MPa with an ultimate strain of 5.35 ± 0.6%, obviously superior to natural nacre (135 MPa and 2%). These excellent mechanical properties arise from the optimum synergy of ion crosslinking and interfacial hydrogen bonds between crosslinked ALG and MMT nanosheets. In addition, these metal ion-crosslinked composite films show different colors, high visible transparency, and excellent UV shielding properties.
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Xu, X., H. Guo, M. Li e H. Fu. "Improving microbially induced calcium carbonate precipitation effects by nacre extractions". Géotechnique Letters 12, n.º 1 (março de 2022): 20–26. http://dx.doi.org/10.1680/jgele.21.00068.
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In microbially induced calcium carbonate precipitation (MICP) process, it is the precipitated calcium carbonate that cements loose sand particles together to improve their mechanical properties. Seashell nacre composed of calcium carbonate is a natural product, which is worth researching for its remarkable hardness, strength and toughness. However, there has been no study that bridges this natural nacre mineralisation with MICP. Therefore, a precedent herein is established to modify the MICP process by way of the water-soluble matrix (WSM) extracted from nacre, where WSM contributes to the great mechanical properties of nacre. This study examines the effects of WSM with different concentrations on urease activity of bacteria and strength as well as the microstructure of bio-cemented sand samples. The results show that a small number of WSM (50 mg/l) can improve the average strength of bio-cemented sand samples by 1·5 times. This is because 50 mg/l WSM can significantly improve the urease activity. Thus, more calcium carbonate crystals are precipitated, and the higher unconfined compressive strength of bio-cemented sand samples is achieved. The microstructures are investigated by x-ray diffraction and scanning electron microscopy. Overall, this study is an unprecedented exploration imitating nacre that hopefully paves way for future studies.
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Li, Xuan Qi, e Hua Chun Zeng. "Calcium Carbonate Nanotablets: Bridging Artificial to Natural Nacre". Advanced Materials 24, n.º 47 (14 de setembro de 2012): 6277–82. http://dx.doi.org/10.1002/adma.201202733.
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Gong, Shanshan, Qi Zhang, Ruliang Wang, Lei Jiang e Qunfeng Cheng. "Synergistically toughening nacre-like graphene nanocomposites via gel-film transformation". Journal of Materials Chemistry A 5, n.º 31 (2017): 16386–92. http://dx.doi.org/10.1039/c7ta03535g.
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Luz, Gisela M., e João F. Mano. "Biomimetic design of materials and biomaterials inspired by the structure of nacre". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, n.º 1893 (28 de abril de 2009): 1587–605. http://dx.doi.org/10.1098/rsta.2009.0007.
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The micro-architecture of nacre (mother of pearl) has been classically illustrated as a ‘brick-and-mortar’ arrangement. It is clear now that hierarchical organization and other structural features play an important role in the amazing mechanical properties of this natural nanocomposite. The more important structural characteristics and mechanical properties of nacre are exposed as a base that has inspired scientists and engineers to develop biomimetic strategies that could be useful in areas such as materials science, biomaterials development and nanotechnology. A strong emphasis is given on the latest advances on the synthetic design and production of nacre-inspired materials and coatings, in particular to be used in biomedical applications.
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Sumitomo, Taro, Hideki Kakisawa, Yusuke Owaki e Yutaka Kagawa. "Structure of Natural Nano-Laminar Composites: TEM Observation of Nacre". Materials Science Forum 561-565 (outubro de 2007): 713–16. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.713.
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Nacre is a natural composite material making up the inner structure of mollusk shells. It has been of great interest in materials research due to its mechanical properties far exceeding that of its individual components: well ordered plates of aragonite (a CaCO3 polymorph) within an organic polymer matrix. Generally the aragonite plates had been treated as single crystals and mechanical behavior explained as the result of micro-scale mechanisms between plates and matrix. However, recent work has shown that the plates themselves are made up of smaller nano-scale structures, which are also thought to contribute to the bulk properties. In this work, transmission electron microscopy (TEM) was used to observe the nano-scale structure of nacre from abalone. “Nanograins” of aragonite surrounded by organic material was observed, showing composite structure within aragonite plates.
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Shao, Yue, Hong-Ping Zhao e Xi-Qiao Feng. "On flaw tolerance of nacre: a theoretical study". Journal of The Royal Society Interface 11, n.º 92 (6 de março de 2014): 20131016. http://dx.doi.org/10.1098/rsif.2013.1016.
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As a natural composite, nacre has an elegant staggered ‘brick-and-mortar’ microstructure consisting of mineral platelets glued by organic macromolecules, which endows the material with superior mechanical properties to achieve its biological functions. In this paper, a microstructure-based crack-bridging model is employed to investigate how the strength of nacre is affected by pre-existing structural defects. Our analysis demonstrates that owing to its special microstructure and the toughening effect of platelets, nacre has a superior flaw-tolerance feature. The maximal crack size that does not evidently reduce the tensile strength of nacre is up to tens of micrometres, about three orders higher than that of pure aragonite. Through dimensional analysis, a non-dimensional parameter is proposed to quantify the flaw-tolerance ability of nacreous materials in a wide range of structural parameters. This study provides us some inspirations for optimal design of advanced biomimetic composites.
Teses / dissertações sobre o assunto "Natural nacre"
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Hantz, Tematuanui a. tehei. "Béton à faible impact environnemental pour la valorisation de coquilles d'huitres perlières Pinctada de Polynésie Française". Electronic Thesis or Diss., Pau, 2024. http://www.theses.fr/2024PAUU3053.
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Les atolls de la Polynésie française, en manque de ressources terrestres, génèrent des ressources économiques grâce à la perliculture. Cette activité produit plus d’un millier de tonnes de déchets annuels sous forme de coquilles d’huîtres perlières (Pinctada Margaritifera et Pinctada Maculata). Ces co-produits nacrés, présentant des performances mécaniques liées à leur microstructure, pourraient, une fois broyés, combler la carence en sable et granulats de construction des archipels producteurs de perles. L’objectif de cette thèse est de formuler un béton à faible impact environnemental, dont le squelette est composé de co-produits de la perliculture locale pour les habitants de Polynésie.Ces coquilles, souvent exposées à la météo tropicale, présentent des états de dégradation variés. La comparaison des performances des nacres fraîches et dégradées montre que l’absence de matière organique dans leur matrice entraîne une diminution de leur résistance à la traction et de leur élongation à la rupture. Toutefois, même dégradée, la nacre conserve des performances élevées parmi les matériaux synthétisés par les mollusques.Par ailleurs, une comparaison des mortiers composés à 100% de granulats issus de coquilles broyées (Pinctada Margaritifera, Pinctada Maculata, mais aussi Crassostrea Gigas et Pecten Maximus) a démontré que le matériau le plus performant n'est pas nécessairement celui réalisé avec les coquilles les plus solides, mais avec les granulats à la géométrie la plus complexe. De plus, la forme plate des granulats réduit la compacité du squelette granulaire, ce qui peut affecter les propriétés du béton. Pour limiter les vides entre les grains, les paramètres de broyage ont été optimisés afin d’obtenir un mélange de deux classes granulaires à faible porosité.Même optimisés, les squelettes granulaires composés à 100% de broyats de coquilles présentent encore une porosité intergranulaire supérieure à 45%. Cela nécessite l’ajout d’une quantité importante d’addition inerte pour conserver une quantité de ciment acceptable tout en comblant les vides. Cet ajout entraîne un asséchement de la pâte, nécessitant un ajustement de la quantité d’eau, en fonction de la porosité de l’addition inerte. Cette méthodologie a permis d’améliorer les formulations de béton, dont la résistance à la compression est passée de 2-5 MPa à plus de 20 MPa.Pour la suite du projet en Polynésie, un transfert des connaissances acquises en laboratoire a été amorcé vers les acteurs socio-économiques à partir de formulations utilisant des co-produits de coquilles d’huîtres d’Arcachon (Crassostrea Gigas), abondantes en Nouvelle-Aquitaine, où l’essentiel des travaux a été mené. L’impact de l’environnement sur des corps morts en béton de broyats de coquilles, placés à l’Île de Ré dans des conditions réelles, a d’abord été étudié dans le but d'y installer des mouillages de bateaux. Ensuite, un démonstrateur non structurel, composé d’un cheminement piéton et d’emmarchements, a été mis en place au pied de la Dune du Pilat dans le cadre de la rénovation du Village des Cabanes, centre d’accueil de ce site classé. En plus de prouver l'implémentation d’un processus innovant, ces chantiers ont démontré que les bétons de broyats de coquilles sont mécaniquement durables et que les formulations peuvent s’adapter à des squelettes non optimisésThe atolls of French Polynesia, despite lacking terrestrial resources, generate economic resources through pearl farming. This activity produces over a thousand tons of waste annually in the form of pearl oyster shells (Pinctada Margaritifera and Pinctada Maculata). These nacre co-products, with mechanical properties linked to their microstructure, could, once crushed, help address the shortage of sand and construction aggregates in the remote pearl-producing archipelagos. The goal of this thesis is to formulate an environmentally friendly concrete for the people of Polynesia, with a skeleton entirely composed of local pearl farming co-products.These shells, often exposed to tropical weather, can present varying levels of degradation. A comparison of the performances of fresh and degraded nacre revealed that the absence of organic matter in their matrix leads to reduced tensile strength and elongation at break. However, even in this state, nacre retains high performance among mollusk-synthesized materials.In addition, a comparison of mortars composed of 100% granular skeletons made from crushed shells (Pinctada Margaritifera, Pinctada Maculata, but also Crassostrea Gigas and Pecten Maximus) showed that the most efficient material is not necessarily the one made from the strongest shells, but rather from those with the most complex geometry. Moreover, the generally flat shape of crushed shells leads to a significant decrease in the compactness of the granular skeleton, which can negatively impact the concrete's properties. To reduce the void volume between grains, grinding parameters were optimized to achieve a blend of two granular classes with the lowest possible porosity.Even when optimized, granular skeletons composed of 100% crushed shells still exhibit intergranular porosity above 45%. Under these conditions, it is necessary to add a substantial amount of inert filler to maintain an acceptable cement quantity while filling all the intergranular voids. This addition, which dries out the filler paste, required a significant adjustment in the water quantity, depending on the porosity of the inert filler used. This methodology allowed the transition from unoptimized shell concrete, with very low compressive strength (2-5 MPa), to a much more efficient concrete with compressive strength exceeding 20 MPa.Looking ahead to the continuation of the project, which will take place in Polynesia beyond this thesis, knowledge transfer from the laboratory to socio-economic actors has begun using formulations incorporating co-products of oyster shells from Arcachon (Crassostrea Gigas), abundant in Nouvelle-Aquitaine, where most of the thesis work was conducted. The environmental impact on concrete structures made from crushed oyster shells, placed on the Île de Ré under real-world conditions with the aim of installing future boat moorings, was first studied. Next, a non-structural industrial demonstrator, consisting of a pedestrian walkway and steps, was implemented at the base of the Dune of Pilat as part of the renovation of the Village des Cabanes, a visitor center for this major classified site. In addition to proving the possible implementation of an innovative process in a complex societal and industrial chain, these projects have demonstrated that crushed shell concrete is mechanically durable and that it is even possible to adapt the formulations to non-optimized skeletons
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ZANINI, JEAN-MARC. "Stocks naturels de nacres - pinctada margaritifera - de polynesie francaise". Paris, EPHE, 1999. http://www.theses.fr/1999EPHE3034.
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L'estimation de stocks naturels de nacres pinctada margaritifera a ete realisee sur 7 lagons des tuamotu-gambier (polynesie francaise), a l'aide d'un protocole d'echantillonnage specifique, faisant intervenir donnees satellite, radiales d'echosondage et plongees de comptage. L'estimation totale du stock en effectif, assortie d'un intervalle de confiance, a ete obtenue sur 6 lagons. L'etude par tranche bathymetrique de 10 metres montre l'existence d'un stock profond (30-50m) representant plus de 50% du stock dans les lagons les plus riches. Les densites de peuplement varient d'un facteur 10 a 1000 d'un lagon a l'autre, les lagons fermes renfermant les stocks les plus importants. La comparaison avec les donnees de peche disponibles (1890-1983) indique un niveau d'exploitation passe raisonnable selon le critere de gulland, et les lagons les plus productifs a l'epoque restent aujourd'hui les plus riches, a l'exception de hikueru et takume qui ont connu des episodes de mortalite massive importants. De meme, le ratio stock en elevage sur stock naturel n'indique pas de risque de surcharge des lagons. La serie chronologique d'estimations de stocks sur l'atoll de takapoto montre une forte variabilite temporelle du stock a l'echelle de quelques annees. Le suivi de 3 sites sur une periode de 1 an confirme ce resultat, un episode de mortalite massive localise dans le temps et dans l'espace ayant pu etre observe. Les mortalites coincident avec des conditions meteorologiques particulieres (vent calme et fortes precipitations) et une baisse de l'oxygene dissous dans les zones les plus profondes et les plus enclavees. Ces crises sont envisagees comme explication de la difference d'effectifs de pinctada margaritifera dans les atolls ouverts et fermes.
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ENGUIX, EGEA ANGEL. "Desarrollo de lineas prioritarias de investigación del hábitat de interés comunitario 1120* Praderas de Posidonia (Posidonion oceanicae) en espacios marinos protegidos de la Comunidad Valenciana". Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/63242.
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[EN] The seagrass Posidonia oceanica is an important ecosystem endemic in the Mediterranean Sea and for their rightful protection they have been included as priority habitat in the European Union habitats directive.
From the priority lines of investigation proposed by the Ministry of Environment, Rural and Marine care for the conversation of the habitat of communal interest 1120*. In regards to the seagrass Posidonia (Posidonion oceanicae) in Spain, in some of the protected marine spaces and managed by the Generalitat Valenciana, the following have been developed:
The line "mapping and cataloging of the habitat type 1120*".
The line "effect of invading species".
The line "Effects of climate change in the priority habitat of seagrass of Posidonia oceanica".
The line "Development and validation of state indicators of the conservation, structure and function of the habitat type 1120*".[ES] Las praderas de Posidonia oceanica son un importante ecosistema endémico del mar mediterráneo y para su protección ha sido incluido como hábitat prioritario en la Directiva de Hábitats de la Unión Europea. De las líneas prioritarias de investigación propuestas por el Ministerio de Medio Ambiente, y Medio Rural y Marino, para la conservación del hábitat de interés comunitario 1120* Praderas de Posidonia (Posidonion oceanicae) en España, en algunos de los espacios marinos protegido creados y gestionado por la Generalitat Valenciana, se han desarrollado las siguientes: La línea "Cartografiado y catalogación del tipo de hábitat 1120*". La línea "Efecto de las especies invasoras". La línea "Efectos del cambio climático en el hábitat prioritario praderas de Posidonia oceanica". La línea "Desarrollo y validación de indicadores de estado de conservación, estructura y función del tipo de hábitat 1120*" .
[CAT] Els herbers de Posidonia oceanica són un important ecosistema endèmic del mar mediterrani i per a la seua protecció ha sigut inclòs com a hàbitat prioritari en la Directiva d'Hàbitats de la Unió Europea. De les línies prioritàries d'investigació proposades per el Ministeri de Medi Ambient , i Medi Rural i Marí, per a la conservació de l'hàbitat d'interés comunitari 1120* Herbers de Posidonia (Posidonion oceanicae) a Espanya, en alguns dels espais marins protegit creats i gestionat per la Generalitat Valenciana, s'han desenrotllat les següents: La línia "Cartografiat i catalogació del tipus d'hàbitat 1120*". La línia "Efecte de les espècies invasores". La línia "Efectes del canvi climàtic en l'hàbitat prioritari herbers de Posidonia oceanica". La línia "Desenrotllament i validació d'indicadors d'estat de conservació, estructura i funció del tipus d'hàbitat 1120*".
Enguix Egea, A. (2016). Desarrollo de lineas prioritarias de investigación del hábitat de interés comunitario 1120* Praderas de Posidonia (Posidonion oceanicae) en espacios marinos protegidos de la Comunidad Valenciana [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63242
TESIS
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Ibrahim, Mohamad. "Le contrat de service pétrolier". Electronic Thesis or Diss., Paris 2, 2020. http://www.theses.fr/2020PA020009.
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Le contrat de service, dernière génération des contrats pétroliers upstream, est apparu dans les années 70 lors de la révolution des pays pétroliers sur les contrats de concession. Depuis cette période, sa propagation dans le monde comme son évolution sont continues. Considéré comme l’un des contrats les plus complexes, son entrée en vigueur est précédée d’une période précontractuelle plus longue que celle d’un contrat classique et suivie d’une période contractuelle qui dure plusieurs décennies. La période précontractuelle est celle de l’étude, de la planification et des procédures de négociation. Elle aboutit à la conclusion d’un contrat conforme aux attentes des parties. C’est lors de la période contractuelle qu’apparaissent les effets du contrat sur les parties mais également sur l’environnement. Les droits et obligations issus du contrat doivent être exécutés conformément aux textes ; le cas échéant, un arbitrage est envisagéThe service contract, the latest generation of upstream petroleum contracts, appeared in the 70s during the revolution in petroleum countries on concession contracts. Since this period, its spread in the world as its evolution are continuous. Considered one of the most complex contracts, its entry into force is preceded by a pre-contractual period longer than that of a classic contract and followed by a contractual period which lasts several decades. The pre-contractual period is that of study, planning and negotiation procedures. It results in the conclusion of a contract that meets the expectations of the parties. It is during the contractual period that the effects of the contract appear on the parties but also on the environment. The rights and obligations arising from the contract must be executed in accordance with the texts; if necessary, arbitration is envisaged
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Heinemann, Fabian David [Verfasser]. "Investigation of biopolymer-mineral interactions in the natural composite material nacre / von Fabian David Heinemann". 2008. http://d-nb.info/992318653/34.
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Akella, Kiran. "Studies for Design of Layered Ceramic Armour Inspired by Seashells". Thesis, 2015. http://etd.iisc.ac.in/handle/2005/3768.
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Pearly layers in seashells, also known as nacreous layers, are reported to be three orders of magnitude tougher than their primary constituent, aragonite. Their high toughness is attributed to a particular structure of alternating layers of natural ceramic and polymer materials. This work tries to emulate it using engineering materials. The thickness, strength, and stiffness of the ceramic layer; the thickness, stiffness, strength, and toughness of the polymer interface layer; and the number of layers are the factors that contribute to different degrees. Furthermore, understanding the relative contribution of different toughening mechanisms in nacre would enable identification of key parameters to design tough engineered ceramics. As a step towards that, in this thesis, layered ceramic beams replicating nacre were studied analytically, computationally, and experimentally. The insights and findings from these studies were then used to develop a new method to make tough layered ceramics mimicking nacre. Subsequently, the use of layered ceramics for armour applications was evaluated.
Based on analytical numerical and experimental studies, we observed that the strength of the layers is a key factor to replicate the high toughness of nacre in engineered ceramics. We also demonstrated that, crack deflection and bridging observed in nacre in studies elsewhere, occur due to the high strength of platelets. Based on these findings, the new method developed in this study uses green alumina-based ceramic tapes stacked with screen printed stripes of graphite. During sintering, graphite oxidizes leaving empty channels in the stack. These channels were filled with tough interface materials afterwards. As a result, a ceramic- polymer composite with more than 2-fold increase in toughness was developed. Subsequently, we evaluated layered ceramics for armour applications based on numerical analysis validated with experiments. Consistent to the trends in literature, we observed that layers degrade the resistance to ballistic impact. However, improved energy absorption is demonstrated in layered ceramics. These conflicting dual trends were not presented and quantified in any earlier studies conducted elsewhere. Another new observation not documented earlier is the effect of interface strength. Using an interface material of sufficient strength, penetration resistance of layered ceramics can be improved beyond monolithic ceramics. Using these findings, new layered ceramic armour can be designed that is cost- effective and better performing than monolithic ceramics.
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Akella, Kiran. "Studies for Design of Layered Ceramic Armour Inspired by Seashells". Thesis, 2015. http://etd.iisc.ernet.in/2005/3768.
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Pearly layers in seashells, also known as nacreous layers, are reported to be three orders of magnitude tougher than their primary constituent, aragonite. Their high toughness is attributed to a particular structure of alternating layers of natural ceramic and polymer materials. This work tries to emulate it using engineering materials. The thickness, strength, and stiffness of the ceramic layer; the thickness, stiffness, strength, and toughness of the polymer interface layer; and the number of layers are the factors that contribute to different degrees. Furthermore, understanding the relative contribution of different toughening mechanisms in nacre would enable identification of key parameters to design tough engineered ceramics. As a step towards that, in this thesis, layered ceramic beams replicating nacre were studied analytically, computationally, and experimentally. The insights and findings from these studies were then used to develop a new method to make tough layered ceramics mimicking nacre. Subsequently, the use of layered ceramics for armour applications was evaluated.
Based on analytical numerical and experimental studies, we observed that the strength of the layers is a key factor to replicate the high toughness of nacre in engineered ceramics. We also demonstrated that, crack deflection and bridging observed in nacre in studies elsewhere, occur due to the high strength of platelets. Based on these findings, the new method developed in this study uses green alumina-based ceramic tapes stacked with screen printed stripes of graphite. During sintering, graphite oxidizes leaving empty channels in the stack. These channels were filled with tough interface materials afterwards. As a result, a ceramic- polymer composite with more than 2-fold increase in toughness was developed. Subsequently, we evaluated layered ceramics for armour applications based on numerical analysis validated with experiments. Consistent to the trends in literature, we observed that layers degrade the resistance to ballistic impact. However, improved energy absorption is demonstrated in layered ceramics. These conflicting dual trends were not presented and quantified in any earlier studies conducted elsewhere. Another new observation not documented earlier is the effect of interface strength. Using an interface material of sufficient strength, penetration resistance of layered ceramics can be improved beyond monolithic ceramics. Using these findings, new layered ceramic armour can be designed that is cost- effective and better performing than monolithic ceramics.
Livros sobre o assunto "Natural nacre"
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Hoffmann, Alicia. Darwin en Sudamérica: Nace un gran naturalista. [Chile]: Instituto de Ecología y Biodiversidad, 2009.
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Slattery, Juliet. Diet / health: Food industry initiatives : a review of developments in the UK food industry following the NACNE and COMA reports. Bradford: Food Policy Research, University of Bradford, 1986.
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Swamp, Jake. Gracias te damos: Una ofrenda de los nativos americanos al nacer de cada día. New York, United States of America: Lee & Low Books, 1996.
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National Association of Corrosion Engineers., ed. NACE International Standard: Petroleum and natural gas industries : materials for use in H2S containingt environments in oil and gas production : Part 3 : Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys. Houston: NACE, 2003.
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National Association of Corrosion Engineers., ed. NACE International Standard: Petroleum and natural gas industries : materials for use in H2S containingt environments in oil and gas production : Part 2 : Cracking-resistant CRAs an the use of cast irons. Houston: NACE, 2003.
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Nacer En Casa/home Birth. Rba Publicaciones Editores Revistas, 2004.
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Grobler, Piet, e Wendy Cooling. All the Wild Wonders. Quarto Publishing Group UK, 2017.
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Impressed Current Test Method for Laboratory Testing of Aluminum Anodes. AMPP, 1990. https://doi.org/10.5006/nace_tm0190-1990.
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Scope This standard test method describes a quality assurance procedure for determining the potential and current capacity characteristics under laboratory conditions for aluminum alloy anodes used for cathodic protection. Field performance of anodes should be evaluated to correspond to actual anode performance. This procedure was established in 1977-78 with revisions in 1980, 1982, and 1985. The committee knows of no NACE entity that has issued a comparable test method. This test method was prepared by NACE Task Group T-7L-2 on Aluminum Anode Quality Control, a component of Unit Committee T-7L on Cathodic Protection in Natural Waters, in conjunction with ASTM Task Group G01-09-02 T-1. This standard is issued by NACE under the auspices of Group Committee T-7 on Corrosion by Waters. These committees are composed of industry representatives, including producers, consumers and interested individuals. This standard test method describes a laboratory procedure for determining the potential and current capacity characteristics of aluminum alloy anodes used for cathodic protection. It provides a means for screening various heats or lots of anodes to determine performance consistency on a regular basis from lot to lot. In utilizing this test method, items such as sampling frequency and performance criteria (i.e., test values at intermediate times) are left to the discretion of the user of the test method. One method for anode potential evaluation and two methods for current capacity evaluations are described.
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Guerrero Sierra, Hugo Fernando, Ana Milena Molina, Alexander Rojas e Douglas Eduardo Molina Orjuela, eds. Gobernanza ambiental: Políticas públicas, sociedad civil y territorio. Universidad Militar Nueva Granada, 2021. http://dx.doi.org/10.18359/9789585103153.
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Hoy en día las problemáticas socio-ambientales han tomado un papel relevante, principalmente, al colocar en la mesa la crisis civilizatoria que ha afectado y cuestionado directamente el modelo económico, social, político y cultural implantado por nuestra civilización. Lo anterior, ha conllevado a que diferentes planes, proyectos y políticas para el cuidado y protección del ambiente y los ecosistemas empiecen a tomar lugar dentro de las agendas gubernamentales internacionales y nacionales, enfocándose especialmente en las realidades y particulares territoriales de las comunidades. En este contexto, el concepto de gobernanza ambiental nace como un referente a la gestión de los recursos naturales que desde un ejercicio político de diferentes actores plantea una discusión sobre como insertar en la agenda pública mecanismos de gobernanza en los programas y acciones a desarrollar desde lo local. Es decir, pensar globalmente pero actuar localmente. En este escenario, el espectro de factores para su abordaje es extenso; por ende, su aplicación puede ser en lo económico, político, cultural, social y ambiental. Dentro de la multiplicidad de enfoques de la gobernanza, este libro se enfoca en el factor ambiental, al considerar que existe un reclamo insistente de las personas que se preocupan por garantizar la sostenibilidad de los recursos naturales en el futuro, puesto que cada vez son más conscientes de la necesidad de generar acciones colectivas para atender a las crecientes y demandantes necesidades de la población mundial. Por consiguiente, el libro Gobernanza Ambiental: Políticas Públicas, Sociedad Civil y Territorio corresponde a todos aquellos lectores que quieran aproximarse desde una perspectiva analítica y reflexiva a los textos que aquí se ofrecen. Invitamos a todos nuestros colegas a hacer un recorrido en un orden secuencial o acudiendo a una ruta autónoma que les permita transitar acorde a sus expectativas. Las investigaciones, reflexiones, hipótesis, metodologías y conclusiones que aquí proponen cada uno de los autores buscan construir nuevos espacios de debate que permitan, desde la interacción con el conjunto de la comunidad académica, generar marcos de análisis multidimensionales que aporten elementos permitentes de análisis más allá de los simplemente conceptuales.
Capítulos de livros sobre o assunto "Natural nacre"
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Juster, Allison, Felix Latourte e Horacio D. Espinosa. "Novel Synthetic Material Mimicking Mechanisms from Natural Nacre". In Experimental and Applied Mechanics, Volume 6, 289–90. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-9792-0_46.
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Denkena, Berend, Luis de Leon, Marijke van der Meer e Analía Moral. "Scratch Tests on Natural Nacre - Reference for Implant Material". In Friction, Wear and Wear Protection, 227–33. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2011. http://dx.doi.org/10.1002/9783527628513.ch27.
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Sumitomo, Taro, Hideki Kakisawa, Yusuke Owaki e Yutaka Kagawa. "Structure of Natural Nano-Laminar Composites: TEM Observation of Nacre". In Materials Science Forum, 713–16. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-462-6.713.
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Zhu, Deju, e Francois Barthelat. "A Novel Biomimetic Material Duplicating the Structure and Mechanics of Natural Nacre". In Conference Proceedings of the Society for Experimental Mechanics Series, 181–87. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-0219-0_25.
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Sarikaya, Mehmet, e Ilhan A. Aksay. "Nacre of Abalone Shell: a Natural Multifunctional Nanolaminated Ceramic-Polymer Composite Material". In Results and Problems in Cell Differentiation, 1–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-540-47207-0_1.
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Wang, Xiao Xiang, Lei Xie, Cheng Luo e Ri Zhi Wang. "Natural Nacre Coatings on Titanium Implant Grown by Fresh Water Bivalve Shell". In Bioceramics 18, 743–46. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-992-x.743.
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Rousseau, Marthe. "Nacre, a Natural Biomaterial". In Biomaterials Applications for Nanomedicine. InTech, 2011. http://dx.doi.org/10.5772/22978.
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"14. Nacre: a biomineral, a natural biomaterial, and a source of bio-inspiration". In Highlights in Applied Mineralogy, 285–300. De Gruyter, 2017. http://dx.doi.org/10.1515/9783110497342-014.
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S., Kalpana, Dinesh R. e Bedabibhas Mohanty. "Biomimetic Lessons Learnt from Nacre". In Biomimetics Learning from Nature. InTech, 2010. http://dx.doi.org/10.5772/8788.
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Delgado Jácome, Jorge Isaac. "Laboratorios en la enseñanza de Ciencias Naturales en la Sierra y Amazonía del Ecuador". In VI Congreso de Educación Salesiana. Educación Salesiana e interculturalidad: reflexiones y prácticas para la transformación social, 121–42. spue, 2025. https://doi.org/10.17163/abyaups.114.923.
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La Guía de sugerencias para actividades experimentales nace en 2017 desde la Subsecretaría de Fundamentos Educativos en conjunto con la Dirección Nacional del Currículo, quienes en busca de enriquecer la enseñanza y el aprendizaje de las Ciencias Naturales, la Física, la Biología y la Química optaron por facilitar a nivel nacional una Guía de sugerencias para actividades experimentales, que sea metodológicamente fácil de usar e interpretar para los docentes a escala nacional.
Trabalhos de conferências sobre o assunto "Natural nacre"
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Gummow, R. A. "Cathodic Protection Criteria - a Critical Review of Nace Standard Rp-01-69". In CORROSION 1986, 1–13. NACE International, 1986. https://doi.org/10.5006/c1986-86343.
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Abstract NACE Recommended Practice RP-01-69 contains criteria for the cathodic protection of steel structures in natural soil and water environments and these criteria have been widely accepted both by the owners of cathodically protected structures and by cathodic protection practitioners. Despite this, it has become increasingly apparent that many of the criteria as stated in the standard are in serious error with the fundamental science and in conflict with other standards and the interpretation of some regulatory agencies. Recent studies, which have appeared in the literature, further confirm that the criteria require revision to ensure that only polarized potentials are used in the criteria and, furthermore, that potential measurements are corrected for IR drop error.
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Murray, John N., Richard A. Hays e Keith E. Lucas. "Testing Indium Activated, Aluminum Alloys Using NACE TM0190-90 and Long Term Exposures". In CORROSION 1993, 1–10. NACE International, 1993. https://doi.org/10.5006/c1993-93534.
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Abstract Four distinct purchase lots of indium activated, aluminum alloy, sacrificial anodes have been evaluated using the NACE Standard Test Method, TM0190-90. A comparison of the Faradaic efficiency values using the H2 evolution and weight loss methods showed quite reasonable agreement. The short-term (two week) laboratory test results agreed with the equivalent data from several samples in limited long-term testing up to 13 months in natural, full strength sea water. The test method itself is reviewed and testing problems and the rational for suggestions of minor changes to the Standard are also presented.
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Teevens, Patrick J., Zhenjin Zhu, Ashish Khera, Saleh Al-Sulaiman, Ahmad AL-Jasmi e Surya Prakash. "Internal Corrosion Direct Assessment of a High-Pressure Wet-Gas Pipeline Using NACE SP0110". In CORROSION 2013, 1–16. NACE International, 2013. https://doi.org/10.5006/c2013-02634.
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Abstract This paper describes the first implementation of a complete four-step wet gas internal corrosion direct assessment (WG-ICDA)1 for a high-pressure natural gas transmission pipeline in Kuwait in compliance with NACE SP0110. The preassessment step collected physical and production data, assessed WG-ICDA feasibility and identified pipeline regions. During the indirect inspection step, multiphase flow modeling was performed using in-house proprietary software to determine flow regime, pressure profile, temperature drop, water content, liquid holdup, solids settling velocity and general corrosion rate along the entire pipeline. Based on the developed dynamic pitting factors, historically cumulative wall losses of the pipeline to date were predicted, and locations with the greatest likelihood of internal corrosion were identified. During the in-the-ditch detailed examination step, remaining wall thicknesses at recommended excavation sites were measured. In the postassessment step, a comparison between the predicted and measured wall losses demonstrates that the conducted WG-ICDA for the subject wet-gas pipeline is successful and effective. The conducted root-cause analysis of metal degradation assists the pipeline operator to ascertain the overall integrity of this asset through optimizing corrosion mitigation strategies and operating conditions.
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Esteban, P., B. Calleja e Alejandra López. "Evaluation of the Stress Corrosion Cracking of Different CRAs in Sour Well Environments". In CORROSION 2018, 1–9. NACE International, 2018. https://doi.org/10.5006/c2018-11450.
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Abstract In selecting materials for corrosive sour oil field environments, the materials of choice must be reliable and cost-effective. Materials have to meet criteria for both corrosion resistance and mechanical properties in sour environments for the required service life. This paper shows the results of the stress corrosion cracking evaluation of two different austenitic corrosion resistant alloys (CRAs), N08028 and N08825 under different conditions of temperature and pressure of H2S and CO2. Those testing conditions are demanded by several end users with oil and natural gas wells operating in different zones onshore and offshore. Depending on the well location the severe environment varies. Corrosion data are presented showing the performance of each grade using the slow strain rate according to NACE TM0198, the NACE TM0177 method A and the NACE TM0316.1-3 Both cold worked materials are typically specified as type 4c and are approved by the NACE MR0175 up to a hardness level of 40 HRC and a maximum yield strength of 150 ksi.
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Caldwell, Eric, Grant Gibson e Lee Jordan. "Further Analysis on M13Cr-110 NACE TM0177 Method a Test Acceptability Prediction". In CORROSION 2011, 1–15. NACE International, 2011. https://doi.org/10.5006/c2011-11099.
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Abstract Martensitic stainless steels continue to be one of the most widely used corrosion resistant alloys in oil and gas developments. Determining if a martensitic stainless steel is acceptable in an unproven environment requires testing to confirm, but predicting the outcome of a given test environment is often initially based on personal experience rather than a qualitative and quantitative assessment. An empirical method for improving the predictability of NACE TM0177 Method A Tensile tests on modified 13Cr 110 ksi grade martensitic stainless steels based on an H2S/Chloride/pH function has previously been developed based on published data in order to address this uncertainty. The environments considered by this function are only limited by the capabilities of the NACE TM0177 Method A test, and provide a method for rapidly estimating if a M13Cr 110ksi grade should pass or fail in multiple different environments. As a follow-on to the development of this empirical method, data points from new tests were used to check the general predictability of the H2S/Chloride/pH function. The general function was modified due to the addition of the new data, and subsequently checked again against a separate set of data. The nature and implications of these findings are discussed and conclusions drawn regarding the performance and value of the methodology for the evaluation of future materials applications.
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Ward, Darren. "Evaluation of ISO & NACE Testing Methods for Accelerated Testing of Offshore Coatings". In CORROSION 2006, 1–17. NACE International, 2006. https://doi.org/10.5006/c2006-06033.
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Abstract The advent of more stringent VOC legislation has resulted in a range of new technologies being utilized in the protective coatings industry. These new technologies require extensive testing to evaluate their performance due to a lack of track record in the market place. This is especially so in the offshore market where premature coating failure can lead to a significant loss of income for the facility owner and expensive repair costs. This has led facility owners to demand ever more stringent accelerated testing protocols to evaluate coating performance. Due to the global nature of the offshore business, an internationally recognized testing protocol is required for the evaluation of high performance coating systems. Both ISO and NACE have recently released test protocols for evaluating coatings in the offshore environment. Recent work has concentrated on evaluation of possible acceptance criteria and comparison of failure mode with that obtained on external coastal exposure. The aim of this paper is to evaluate these new standards using a number of typical offshore schemes and report the results obtained.
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Rippon, I. J. "A New Standard and State of the Art Report from TG169 Cathodic Protection in Seawater". In CORROSION 2006, 1–15. NACE International, 2006. https://doi.org/10.5006/c2006-06101.
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Abstract TG169 “Cathodic Protection in Seawater” technical committee has two assignments, to review the application and potential changes to ISO 15589-2 Petroleum and Natural Gas Industries—Cathodic Protection of Pipeline Transportation Systems and to write a committee report on offshore pipeline CP: electrical isolation/continuity and coating issues. Two new NACE documents have been issued in the last year under TG169 to meet these assignments. A modified adoption of “ISO 15589-2 Cathodic protection of pipeline transportation systems - Part 2: Offshore Pipelines”, was issued, making this a NACE standard. For items than were not included in ISO standard, but were still thought to be important, a NACE technical committee report was produced entitled “Electrical Isolation/Continuity and Coating Issues for Offshore Pipeline Cathodic Protection Systems”. This paper will give an explanation of the key issues of these two documents. Ian Rippon is the current chairman of TG169, and this paper represents the work done on that committee.
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Morales, Ivan, John Houben e Jorge J. Perdomo. "Qualification of Integral Finned UNS-S32205 Heat Exchanger Tubing for Refinery Wet H2S Service". In CORROSION 2016, 1–12. NACE International, 2016. https://doi.org/10.5006/c2016-07887.
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Abstract This paper describes the work process followed for the development of a new manufacturing route including annealing after finning of UNS-S32205 heat exchanger tubing to reduce the hardness of the tube to meet the hardness and delivery conditions requirements specified on NACE MR0103 for UNS-S32205 alloy. Integrally finned heat exchanger tubing has been widely used by Chemical Process Industry (CPI) and Liquefied Natural Gas (LNG) industries as a way to optimize heat transfer performance of shell and tube heat exchangers, however as these become more popular in Refining industry additional requirements need to be considered to prevent specific corrosion mechanism like sulfide stress corrosion cracking (SSC) as described by NACE MR0103. The manufacturing process used to fin the tubes is an intense cold work process that results in hardness as high as 430 HV 10 (37 HRC) and depending on which hardness conversion is used the whole cross section of the tube could be above the NACE MR0103 hardness limits for the alloy. The qualification discussed in this article included corrosion testing per ASTM(2) A923C, microstructural analysis, complete cross section micro hardness (HV10) survey of the tubes and cracking testing per NACE TM0177 to compare the SSC resistance of the tubes in their “as-finned” condition versus “finned and annealed”.
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Ward, Darren. "Correlation of Accelerated Corrosion Testing with Natural Exposure after 6+ Years in a Coastal Environment". In CORROSION 2008, 1–9. NACE International, 2008. https://doi.org/10.5006/c2008-08003.
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Abstract In the coatings industry new technologies are often necessary to produce high solids materials which are required to meet current and future VOC legislation. Due to the lack of track record with some of these technologies it is essential to use 00 It must be performed using commercially available equipmentPerformed in a relatively short time period (max 12 months)The results should correlate with real life exposure Presently there are a number of internationally recognized accelerated corrosion tests which can be used including NACE TM0304, ASTM B117, ASTM D5894 and ISO 20340. The following paper will discuss each of the test methods listed above and correlate data produced from the accelerated testing of various high performance coating systems with performance in real life exposure at a coastal environment. The major findings are that cyclic corrosion testing produces a higher degree of correlation with natural weathering and therefore provides a more reliable method of predicting coating performance.
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Djurin, Antonia, Ming Shen, Dijana Zrinski e Julie Holmquist. "Compostable VCI Film Brings Corrosion Protection ‘Back to Nature’". In CONFERENCE 2024, 1–8. AMPP, 2024. https://doi.org/10.5006/c2024-20431.
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Abstract Presented here is a certified industrial compostable vapor phase corrosion inhibitor film that meets EN 13432/ASTM D6400 standards for commercial compostability. It passes NACE VIA (Vapor Inhibiting Ability) requirements and provides the same corrosion protection as conventional inhibitor film. But unlike conventional film going to a landfill or, worse, becoming ocean debris, this compostable film will biodegrade in an industrial compost site and go back to soil components without posing an ecotoxicity threat to plant growth. The paper will discuss the material’s construction, mechanical properties, and corrosion performance. This film has been adopted successfully by a major European auto maker for shipping parts around the world.
Relatórios de organizações sobre o assunto "Natural nacre"
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Clark, Mooney e Colwell. L52198 External Corrosion Direct Assessment Validation. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), março de 2005. http://dx.doi.org/10.55274/r0011350.
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This report covers the evaluation and analyses of ten ECDA projects conducted by nine natural gas pipeline operators. The objective of this work was validation of the ECDA methods proposed in NACE RP 0502 as an integrity assessment method that could be used in place of or along the pressure testing and in-line inspection. Most of the ECDA projects utilized CIS, DCVG, PCM, and ACVG and other indirect inspection tools to a lesser extent.
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Thompson e Lawson. L51792 External Corrosion Control Monitoring Practices - Volumes I and II. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), maio de 2000. http://dx.doi.org/10.55274/r0010173.
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The primary means of corrosion control for buried pipelines is the use of an external pipeline coating and the application of cathodic protection (CP). Monitoring the effectiveness of the corro sion control system is critical to the safe operation of natural gas pipelines. NACE International has established criteria andrecommended practices for monitoring the effectiveness of CP systems (RPO169-96). These practices and criteria have generally been accepted by regulatory agencies. Over the years a significant amount of research has been performed that is related to monitoring practices. Much of this research has been directed at improving measurement techniques that are aimed at satisfying the NACE criteria. In general, no significant effort has been made to incorporate research into currently used monitoring practices. The overall objectives of this project were (1) to consolidate research previously performed on monitoring the effectiveness of cathodic protection of pipelines, (2) to analyze the different monitoring techniques in light of the research, and (3) to produce monitoring guidelines that describe the application of these monitoring techniques for typical natural gas pipelines. The scope of this project was limited to the review of previous work, both PRCI funded and the open literature, and discussions with industry personnel. No field work or laboratory experiments were conducted. This project was further limited to the review of methodologies related to monitoring the effectiveness of the CP system and does not include methods for evaluating coatings. The research project was divided into the following two tasks: Task 1 - Review of Research and Practices and Task 2 - Development of Guidelines. This work was a consolidation of research that has been performed by the PRCI and others over the past several years. This review took the individual monitoring techniques (on-potential, off-potential, depolarized potential, close interval survey, etc.) and applied them to the typical pipeline scenarios (poorly-coated line, well-coated line, foreign line crossing, area with dynamic stray current, etc.). Each individual monitoring technique is summarized in terms of purpose, description, application, limitations, special considerations, and equipment requirements. Each pipeline scenario is supported with composite and line maps and the guidelines for each scenario are described in terms of a general description, applicable techniques, special considerations, measurement procedures, measurement locations, measurement frequency, applicable criteria, and data interpretation.
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Nelson, Margot, Michael Antonioni, Vincent Santucci e Justin Tweet. Oxon Run Parkway: Paleontological resource inventory; supplement to the National Capital Parks-East paleontological resource inventory. National Park Service, agosto de 2021. http://dx.doi.org/10.36967/nrr-2287217.
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Oxon Run Parkway (OXRN) is a 51-hectare (126-acre) natural area within Washington, D.C. administered by the National Park Service under National Capital Parks East (NACE). The original plan called for a road, slated to follow Oxon Run stream, but this never came to fruition; despite this, the moniker stuck. The majority of the original Oxon Run Parkway is managed by the District of Columbia. The section of Oxon Run Parkway under NPS jurisdiction contains wetlands and forests, as well as the only McAteean magnolia bogs still remaining in the District. The lower Cretaceous Potomac Group, known as one of the few dinosaur-bearing rock units on the east coast of North America, crops out within Oxon Run. One of the most prevalent fossil-bearing resources are the siderite, or “bog iron” sandstone slabs that sometimes preserve the footprints or trackways of various vertebrates, including dinosaurs. Such trackways have been reported from Potomac Group outcrops throughout the Atlantic Coastal Plain of Maryland and Virginia. In 2019, National Capital Parks-East took possession of such a track, referred to a dinosaur, collected by paleontologist Dr. Peter Kranz. This report was compiled after a paleontological survey of Oxon Run Parkway and is intended as a supplement to the National Capital Parks East Paleontological Resource Inventory (Nelson et al. 2019). This report contains information on the history of Oxon Run Parkway and its geology, as well as discussion of the fossil track.
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Botros. L51715 Field Testing the Criteria for Cathodic Protection of Buried Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), fevereiro de 1994. http://dx.doi.org/10.55274/r0010115.
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There are three (3) documented Cathodic Protection (CP) criteria included in the NACE standards. The appropriate use of these are often debated and sometimes thought to be conservative in dry soils and possibly insufficient in some wet soil conditions. The need exists to evaluate the risks of an improperly installed and/or maintained CP system. The criteria for cathodic protection have been the subject of various research projects conducted for the Pipeline Research Council International, Inc. (PRCI) over a number of years. The programs have responded to the need to establish whether the present criteria are adequate or inadequate, and under what conditions, and whether the specific requirements for protection may depend upon the particular soil environment. The results of this study provide a comprehensive overview of the technical literature and the laboratory studies that formed the basis for this work. The results of this work include the first systematic study of the criteria as installed in the field. Field studies were initiated in 1984 with a multiyear (thru 1994) plan and objective of verifying the requirements for protection in a variety of natural environments, some of which were studied in the earlier laboratory research. Part I: Results of the research.Part II: Applications to the study, the limitations, methods of determining requirements of the pipeline, and the measurements needed to implement the results (60 figures and 56 tables).Part III: Study data (100 pages of charts and tables)