Academic literature on the topic 'Additifs de conduction'
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Journal articles on the topic "Additifs de conduction"
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Garcia, Michele Vargas, Dayane Domeneghini Didoné, José Ricardo Gurgel Testa, Rúbia Soares Bruno, and Marisa Frasson de Azevedo. "Visual Reinforcement Audiometry and Steady-State Auditory Evoked Potential in infants with and without conductive impairment." Revista CEFAC 20, no. 3 (May 2018): 324–32. http://dx.doi.org/10.1590/1982-0216201820312217.
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ABSTRACT Purpose: to compare the findings of minimum levels of answers through air and bone conductions between the Visual Reinforcement Audiometry and the Steady-State Auditory Evoked Potential in infants from six to twelve months, with and without conductive disorder. Methods: sixty children aged six to twelve months were evaluated, 30 presenting conductive disorder, and 30 not presenting it. Children with malformation in the external auditory meatus with neurological alteration and / or genetic syndrome were excluded, as well as patients with sensorineural or mixed hearing loss. The infants were subjected to Visual Reinforcement Audiometry and Steady-State Auditory Evoked Potential evaluation through air and bone conduction on the same day. The results of both assessments were compared and correlated. Results: in the comparison through air conduction, for the group without conductive disorder of the medium ear, the minimum levels of response for 500 and 1000Hz were lower (better thresholds) for Steady-State Auditory Evoked Potential in both ears, and through bone conduction were very similar in all frequencies. Concerning the infants that present conductive disorder, the responses through air conduction were better in all frequencies evaluated when obtained via Steady-State Auditory Evoked Potential test. Through bone conduction, the results were very similar for both groups. Conclusion: it was possible to compare the findings to the minimum levels of response through air and bone conductions between the Visual Reinforcement Audiometry and the Steady-State Auditory Evoked Potential, being that the comparison for bone conduction in both groups presents an equivalence in the results, being very similar. In addition, for the air conduction, in the control group, there was proximity of responses of some frequencies, while the values for the Steady-State Auditory Evoked Potential test were better than the behavioral responses in the conductive disorder group.
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Gaponov, A. V. "Non-ohmic conduction in tin dioxide based ceramics with copper addition." Semiconductor Physics Quantum Electronics and Optoelectronics 14, no. 1 (February 28, 2011): 71–76. http://dx.doi.org/10.15407/spqeo14.01.071.
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Zhang, Jianye, Zhiyong Huang, Chengen He, Jinlong Zhang, Peng Mei, Xiaoyan Han, Xianggang Wang, and Yingkui Yang. "Binary carbon-based additives in LiFePO4 cathode with favorable lithium storage." Nanotechnology Reviews 9, no. 1 (September 27, 2020): 934–44. http://dx.doi.org/10.1515/ntrev-2020-0071.
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AbstractA pairwise coupling of 0D Super-P (SP), 1D carbon nanotubes (CNTs), and 2D graphene nanosheets (GNs) into binary carbon-based conductive additives was used here for the LiFePO4 cathode in lithium-ion batteries. For comparison, the LiFePO4 cathode with SP, CNT, or GN unitary conductive agent was also examined. Electrochemical test results suggest that the cathodes with binary conducting additives present greatly improved electrochemical performance than the traditional cathode system (only SP used). Especially, the LiFePO4 cathode containing 3% CNT component exhibits the highest specific capacity and the best cycling stability among all the cathodes with binary conducting additives, indicating that an appropriate amount of CNTs is critical in enhancing the conductivity and practical capacity output. However, an excess of CNTs leads to entangling with each other, hampering the uniform distribution of active materials and resulting in poor electrode performance. Furthermore, the combination of CNT and GN can effectively improve the capacity and cycling stability of the LiFePO4 cathodes due to the synergistic effect of 3D conductive networks constructed by the two.
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Sun, Jinru, Xuanjiannan Li, Xiangyu Tian, Jingliang Chen, and Xueling Yao. "Dynamic electrical characteristics of carbon fiber-reinforced polymer composite under low intensity lightning current impulse." Advanced Composites Letters 29 (January 1, 2020): 2633366X2094277. http://dx.doi.org/10.1177/2633366x20942775.
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The distribution and conduction path of lightning current inside carbon fiber-reinforced polymer (CFRP) composites subjected to lightning strikes are determined by their dynamic conductive characteristics. An experimental platform that generates lightning current impulses with variable parameters was established to obtain the equivalent conductivities of CFRPs with different laminated structures. The experimental results indicated that the through-thickness conductivity (10−3 S/mm) was much lower than the in-plane conductivity (100 S/mm). Then, the dynamic conduction model of CFRPs was analyzed based on the anisotropic nonlinear conductivities of CFRPs under lightning currents of 50–1000 A. The CFRP laminate could be regarded as a series circuit of resistance and inductance. The dynamic conductance of the CFRP laminate first increased and then decreased during the single lightning current strike process, which was closely related to the conductive properties of the interlaminar resin. The inductive properties of the CFRP material were manifested in the test results, which showed that the voltage reached the peak value prior to the current waveform and the equivalent conductivities of the CFRPs increased as the rate of increase decreased and the duration increased. In addition, the equivalent inductance of the carbon fiber network was found to be an important part of the inductive effect of CFRP laminates. This research is helpful for understanding the complicated relationships in the lightning current conducting process and can provide experimental and theoretical support for CFRP coupled electrical–thermal simulation studies of lightning direct effects.
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Finegan, Ioana C., and Gary G. Tibbetts. "Electrical conductivity of vapor-grown carbon fiber/thermoplastic composites." Journal of Materials Research 16, no. 6 (June 2001): 1668–74. http://dx.doi.org/10.1557/jmr.2001.0231.
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Conducting polymers are required for applications such as radio frequency interference shielding, primerless electrostatic painting, and static discharge. We have used vapor-grown carbon fiber (VGCF) as an additive to investigate conducting thermoplastics for these applications. The electrical properties of VGCF/polypropylene (PP) and VGCF/nylon composites are very attractive compared with those provided by other conventional conducting additives. Because of the low diameter of the VGCF used, the onset of conductivity (percolation threshold) can be below 3 vol%. Because of the highly conductive nature of the fibers, particularly after a graphitization step, the composites can reach resistivities as low as 0.15 Ω cm.
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Li, Ji, Thomas Wasley, Duong Ta, John Shephard, Jonathan Stringer, Patrick J. Smith, Emre Esenturk, Colm Connaughton, Russell Harris, and Robert Kay. "Micro electronic systems via multifunctional additive manufacturing." Rapid Prototyping Journal 24, no. 4 (May 14, 2018): 752–63. http://dx.doi.org/10.1108/rpj-02-2017-0033.
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Purpose This paper aims to demonstrate the improved functionality of additive manufacturing technology provided by combining multiple processes for the fabrication of packaged electronics. Design/methodology/approach This research is focused on the improvement in resolution of conductor deposition methods through experimentation with build parameters. Material dispensing with two different low temperature curing isotropic conductive adhesive materials was characterised for their application in printing each of three different conductor designs, traces, z-axis connections and fine pitch flip chip interconnects. Once optimised, demonstrator size can be minimised within the limitations of the chosen processes and materials. Findings The proposed method of printing z-axis through layer connections was successful with pillars 2 mm in height and 550 µm in width produced. Dispensing characterisation also resulted in tracks 134 µm in width and 38 µm in height allowing surface mount assembly of 0603 components and thin-shrink small outline packaged integrated circuits. Small 149-µm flip chip interconnects deposited at a 457-µm pitch have also been used for packaging silicon bare die. Originality/value This paper presents an improved multifunctional additive manufacturing method to produce fully packaged multilayer electronic systems. It discusses the development of new 3D printed, through layer z-axis connections and the use of a single electrically conductive adhesive material to produce all conductors. This facilitates the surface mount assembly of components directly onto these conductors before stereolithography is used to fully package multiple layers of circuitry in a photopolymer.
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Lin, Jian Yang, and Bing Xun Wang. "Resistive Switching Characteristics in Nanocrystalline Silicon Films for Conductive-Bridging Resistive Random-Access Memory Applications." Applied Mechanics and Materials 284-287 (January 2013): 2565–69. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.2565.
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In this paper, intrinsic nanocrystalline silicon thin films were deposited onto the ITO/glass substrates by PECVD and were used as the conduction material for the conductive-bridging random-access memory devices. The resistive switching characteristics of the nanocrystalline silicon thin films were investigated. Experimental results have shown that the stable bipolar resistive switching of the nc-Si films and retention time over 104s. In addition, the current conduction mechanism of the nanocrystalline silicon films was examined with XPS depth file analysis. It clearly indicates that the conduction mechanism for the resistive switching is formation metallic bridges come form metal cation migration in the nanocrystalline silicon films.
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Kamaluddin, Siti, Denni Kurniawan, Muhammad Saifullah Abu Bakar, and Zuruzi Abu Samah. "Biochar as a Conducting Filler to Enhance Electrical Conduction Monitoring for Concrete Structures." Key Engineering Materials 847 (June 2020): 149–54. http://dx.doi.org/10.4028/www.scientific.net/kem.847.149.
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Smart and resilient concrete structures will require building materials such as cements that sense flaws. One mechanism of crack detection in structures is monitoring their electrical conduction. Two mechanisms of charge in cement is ionic movement and moisture diffusion. Carbon rich electrically-conducting char is produced by pyrolyzing rice husks and can be used to enhance electrical conduction in cement. This paper studies the evolution of electrical properties in ordinary Portland cement added with up to 15 wt% rice husk-derived biochar. Resistance of cements decreased with increasing biochar addition while moisture loss and resistance both increase as curing time increases. Cement with 15 wt% biochar experiences the largest moisture loss and the most conducting. This suggest charge transport along percolation paths of biochar particles is dominant mechanism in these materials. Electron microscopy and energy dispersive spectroscopic studies reveal formation of Ettringite phase and good wetting/bonding at the interface of biochar particles and cement.
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Cao, Zhengfeng, Yanqiu Xia, and Xiangyu Ge. "Conductive capacity and tribological properties of several carbon materials in conductive greases." Industrial Lubrication and Tribology 68, no. 5 (August 8, 2016): 577–85. http://dx.doi.org/10.1108/ilt-07-2015-0113.
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Purpose The purpose of this paper is to synthesize a new kind of conductive grease which possesses a prominent conductive capacity and good tribological properties. Design/methodology/approach A two-step method was used to prepare complex lithium-based grease. Ketjen black (KB), acetylene black (AB) and carbon black (CB) were characterized by transmission electron microscope and used as lubricant additives to prepare conductive greases. Conductive capacity was evaluated by a conductivity meter, a surface volume resistivity meter and a circuit resistance meter. Tribological properties were investigated by a reciprocating friction and wear tester (MFT-R4000). The worn surfaces were analyzed by a scanning electron microscope, Raman spectroscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscope. Findings The conductive grease prepared with KB has a prominent conductive capacity at room temperature, 100°C and 150°C. Further, this conductive grease also possesses better tribological properties than AB and KB greases. When the concentration of KB is 1.8 Wt.%, the coefficient of friction and wear width reduced by 11 and 14 per cent, respectively. Originality/value This work is a new application of nanometer KB as a lubricant additive in grease, which provides a direction for preparing conductive grease. The conductivity and tribology experiments have been carried out though the variation of experiment conductions.
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Polczyk, Tomasz, Wojciech Zając, Magdalena Ziąbka, and Konrad Świerczek. "Mitigation of grain boundary resistance in La2/3-xLi3xTiO3 perovskite as an electrolyte for solid-state Li-ion batteries." Journal of Materials Science 56, no. 3 (September 30, 2020): 2435–50. http://dx.doi.org/10.1007/s10853-020-05342-7.
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Abstract In this work, we report that modification of the chemical composition of grain boundaries of La2/3-xLi3xTiO3 double perovskite, one of the most promising Li-ion conducting solid electrolytes, can be a convenient and versatile way of controlling the space charge potential, leading to a mitigated electrical resistance of the grain boundaries. Two groups of additives are investigated: lithium-enriching agents (Li3BO3, LiF) and 3d metal ions (Co2+, Cu2+), both expected to reduce the Schottky barrier. It is observed that Li-containing additives work effectively at a higher sintering temperature of 1250 °C. Regarding copper, it shows a much stronger positive impact at lower temperature, 1150 °C, while the addition of cobalt is always detrimental. Despite overall complex behavior, it is documented that the decreased space charge potential plays a more important role in the improvement of lithium conduction than the thickness of the grain boundaries. Among the proposed additives, modification of La2/3-xLi3xTiO3 by 2 mol.% Cu2+ results in the space charge potential reduction by 32 mV in relation to the reference sample, and the grain boundary specific conductivity increase by 80%, as measured at 30 °C. Introduced additive allows to obtain a similar effect on the conductivity as elevating the sintering temperature, which can facilitate manufacturing procedure. Graphic abstract
Dissertations / Theses on the topic "Additifs de conduction"
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Storck-Gantois, Fanny. "Effet de la compression et de l’ajout d’additifs sur l’amélioration des performances d’un accumulateur au plomb." Paris 6, 2008. http://www.theses.fr/2008PA066370.
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Les travaux de cette thèse visent le développement d’un accumulateur au plomb-acide aux propriétés améliorées en combinant l’utilisation d’additifs et la mise en compression des cellules. L’utilisation d’additifs poreux vise à favoriser la diffusion de l’électrolyte au sein de la matière active positive et l’utilisation d’additifs de conductivité tend à optimiser le réseau de conduction des matériaux actifs. Le maintien de la cohésion des matières en cyclage est assuré par la mise en compression des électrodes. Dans cet objectif, un protocole de fabrication d’électrodes positives a été développé au laboratoire. Un comportement de référence a ensuite été définit en déterminant les performances électriques et les caractéristiques des électrodes témoins soumises à des pressions allant de 0 à 1bar. Puis les effets des additifs ont été évalués lors d’applications en compression. Notre but étant également une meilleure compréhension du système plomb-acide et du mode de fonctionnement des additifs, des mécanismes pour expliquer l’évolution texturale des matériaux actifs positifs en compression et l’interaction entre les additifs et l’application d’une pression ont été proposés
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Douin, Myriam. "Etude de phases spinelle cobaltées et d'oxydes lamellaires dérivés de Na0,6CoO2 employés comme additifs conducteurs dans les accumulateurs Ni-MH." Bordeaux 1, 2008. http://www.theses.fr/2008BOR13562.
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La technologie mousse utilisée actuellement pour la conception des électrodes positives des batteries Ni-MH, nécessite l'emploi d'un additif conducteur au cobalt en raison de la mauvaise conductivité électronique de la matière active Ni(OH)2. La recherche de nouveaux composés au cobalt constitue un point clé en vue du développement de ces batteries vers des applications de forte puissance. Dans ce contexte, deux additifs conducteurs potentiels ont été étudiés au cours de ces travaux de thèse. La première partie de l'étude a été focalisée sur des phases spinelle HxLiyCo3-8O4 conductrices, synthètisées par oxydation électrochimique de l'oxyde CoO. Une forte influence du traitement thermique du matériau sur sa conductivité électronique a été mise en évidence. Des analyses par diffraction des rayons X in situ, ATG-SM, RMN et des mesures de conductivités électroniques ont permis de mettre en évidence une redistribution catonique au sein de la structure spinelle, conduisant à une augmentation du rapport atomique Co4+/Co3+ dans le réseau octaédrique [Co2O4], sans variation du degré d'oxydation moyen du cobalt. Il s'ensuit une augmentation de la conductivité elctronique du matériau de trois ordres de grandeur. Le second axe de la thèse concerne l'étude du comportement électrochimique de l'additif Na0,6CoO2. Les réactions échange/insertion des ions alcalins mises en jeu au cours des processus d'oxydation et de réduction de la phase initiale ont été étudiées en détail et un mécanisme a pu être proposé. L'oxyhydroxyde de cobalt hydraté γ, formé par oxydation de Na0,6CoO2 au cours du cyclage, s'est avéré présenter de très bonnes performances lors de tests en batteries. La formation d'une phase interstratifiée intermédiaire, qui possède une cinétique de réduction lente, permet de conserver la stabilité de l'additif à bas potentiel et par conséquent, l'intégralité du réseau conducteur.
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Bouteloup, Rémi. "Estimation de propriétés d'intérêt pour les électrolytes liquides." Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4016/document.
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Les électrolytes liquides, composés d’un sel dissous dans un solvant, interviennent dans la composition des batteries et font l’objet de nombreuses études afin d’améliorer leurs performances et leur sécurité. Parmi toutes les propriétés essentielles d’un électrolyte, la plus importante est sa conductivité ionique, qui influe sur les performances de la batterie. Pour un sel donné, la conductivité est elle-même principalement déterminée par les propriétés physico-chimiques du solvant comme sa constante diélectrique ou sa viscosité. L’objectif de cette étude est de développer des modèles permettant d’estimer des propriétés d’intérêt des électrolytes liquides, afin d’offrir un gain de temps aux chimistes, qui pourront éliminer les compositions inadéquates du point de vue de telle ou telle propriété. La première partie de cette étude présente une méthode pour estimer la conductivité d’un électrolyte, constitué d’un sel LiPF6 dans un mélange de solvants. Cette méthode s’appuie sur de nouvelles équations, pour estimer les paramètres de l’équation de Casteel-Amis, à partir de propriétés physico-chimiques du mélange de solvants, dont la constante diélectrique. La seconde partie présente a par ailleurs permis de développer une méthode pour estimer la constante diélectrique d’un solvant pur, à partir de sa structure chimique. Cette méthode s’appuie sur de nouveaux modèles additifs qui permettent d’estimer les paramètres de l’équation de Kirkwood-Fröhlich. Parmi ces modèles, deux d’entre eux permettent l’estimation de la densité et de l’indice de réfraction d’un composé liquide à température ambiante. L’ensemble des modèles développés sont utilisables via une interface utilisateurLiquid electrolytes, composed of a salt dissolved in a solvent, are used in the composition of batteries and are the subject of numerous studies to improve their performance and safety. Of all the essential properties of an electrolyte, the most important is its ionic conductivity, which influences the battery's performance. For a given salt, the conductivity itself is mainly determined by the physico-chemical properties of the solvent such as its dielectric constant or its viscosity. The objective of this study is to develop models to estimate properties of interest of liquid electrolytes, in order to offer time savings to chemists, who will be able to eliminate inadequate compositions from the point of view of such or such property. The first part of this study presents a method to estimate the conductivity of an electrolyte, consisting of a LiPF6 salt in a solvent mixture. This method is based on new equations, to estimate the parameters of the Casteel-Amis equation, based on the physico-chemical properties of the solvent mixture, including the dielectric constant. The second part also presents a method to estimate the dielectric constant of a pure solvent, based on its chemical structure. This method is based on new additive models that estimate the parameters of the Kirkwood-Fröhlich equation. Two of these models estimate the density and refractive index of a liquid compound at room temperature. All the models developed can be used via a user interface
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Lambert, Romain. "Nouveaux copolymères et nanostructures dérivés de liquides ioniques à base d'imidazoliums : applications en catalyse et comme additifs conducteurs ioniques." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0306/document.
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Des poly(liquides ioniques) (PILs) arrangés sous la forme de copolymères statistiques,de nanoparticules à chaine unique ou bien sous la forme de copolymères à blocs autoassemblés ont été employés comme précurseurs de carbènes N-hétérocycliques (NHC)s à des fins de catalyses organiques ou organométalliques. L’introduction d’anions acétate dans des unités PIL dérivés d’imidazolium permet la génération in situ de NHCs actifs en catalyse. Les nanoparticules composées d’une chaine unique polymère repliée sur elle-même (SCNP) ont été spécialement conçues selon deux stratégies impliquant, d’une part, une réaction d’autoquaternisation entre groupements fonctionnels antagonistes portés par la chaine et, d’autre part, une réaction de complexation organométallique à l’aide d’un sel de palladium. Dans lesdeux cas, les chaines polymères ont été obtenues par polymérisation contrôlée (méthode RAFT). Les copolymères à blocs amphiphiles comportant un bloc PIL fonctionnalisé par du palladium ont été synthétisés par polymérisation RAFT et auto-assemblés dans l’eau sous forme de micelles.Un effet de confinement des sites catalytiques a clairement été démontré à travers des réactions de catalyse pour les couplages de Suzuki et de Heck dans l’eau, avec un gain cinétique très net par rapport à des homologues non micellisés, en plus d’une grande facilité de recyclage de ces supports micellaires.Enfin, des copolymères à blocs à base de PIL-benzimidazolium à contre anion bis(trifluoromethane)-sulfonylimide de lithium ont été développés comme agents dopants conducteurs ioniques de matrices structurantes PS-b-PEO. Des mélanges configurés en films minces avec une quantité minimale d’agent dopant ont conduit dans certaines conditions à des valeurs optimales de conductivité ionique grâce à une nano structuration des films à longue distancePoly(ionic liquid)s (PILs) in the form of random copolymers, single chain nanoparticles(SCNPs), or self assembled block copolymers have been used as N-heterocyclic carbenes(NHCs) precursors for the purpose of organic and organometallic catalysis. Introducing acetate derivative counter anion in imidazolium based PIL units enable in situ generation of catalyticallyactive NHC. SCNPs have been specially designed along two strategies including, firstly, a self quaternization reaction involving two antagonists groups supported on to the polymer chain and,secondly, an organometallic complexation featuring palladium salt. Both polymeric precursors were obtained using RAFT as controlled polymerization method. Amphiphilic block copolymers composed of a PIL block functionalized by palladium have been synthesized by RAFT and self-assembled in water, leading to micellar structures. Confinement effect has been demonstrated through Suzuki and Heck coupling in water showing kinetic gain compared to molecular homologue in addition to an easier recycling method.Finally, PIL-benzimidazolium based block copolymers with lithium bis(trifluoromethane)-sulfonylimide anion have been developed as ionic conductor doping agent for PS-PEO matrix. Thin films blends with minimum doping agent amount led to optimum ionic conductivity owing tolong range order
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Khan, Imran. "Electrically conductive nanocomposites for additive manufacturing." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670587.
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La tesi se centra en l’ús de nanocomposites conductors elèctricament en la fabricació d’additius. En aquest escenari, dos tipus de nanocomposites estan preparats per utilitzar-los com a matèria primera per a la impressió de nanocomposites conductors elèctricament amb dos tipus diferents de matrius; (1) un polímer termoplàstic i (2) una resina termoestable. Els nanotubs de carboni es van utilitzar com a partícules conductores elèctriques de nanoestructura. Aquestes nanoestructures formen xarxes complexes en una matriu de polímer de manera que el material de la matriu es transforma d’un material aïllant en un material conductor elèctricament. La policaprolactona és un polímer semicristal·lí i es considera material matricial adequat entre la classe de polímers termoplàstics, ja que ofereix unes excel·lents característiques reològiques, de flux i elàstiques. Les cadenes es van imprimir mitjançant una extrusora bio i es va mesurar la conductivitat elèctrica en aquestes cadenes amb l’efecte de la deformació uniaxial. La microstructura canvia sota l’efecte de la deformació uniaxial, provocant una alteració de l’orientació de nanotubs de carboni a la matriu de policaprolactona. Com a conseqüència de la reordenació de nanotubs, les vies conductores es desorganitzen o s’organitzen que poden augmentar o disminuir la conductivitat elèctrica en els nanocomposites. Les radiacions del sincrotró s’utilitzen per sondar aquests canvis en la microestructura. Es van preparar diferents composicions mitjançant nanotubs de carboni i es van estudiar les mostres impreses en termes de conductivitat elèctrica i microestructura mitjançant radiacions de sincrotró. A partir de l’anàlisi, es proposa un model que pugui predir la conductivitat elèctrica sota l’efecte de la deformació uniaxial. En termes de polímers termoestables, s’introdueix un sistema senzill per a la impressió de nanocomposites basats en polímers termoset. En un dels capítols es proporciona un detall complet del sistema d’impressió i de la tinta nanocomposita. Es va preparar tinta de nanocomposites basada en epoxi per contenir nanotubs de carboni com a partícules de farciment amb una petita porció de polímer termoplàstic, policaprolactona. Les mostres impreses estan subjectes al biaix extern que indiquen que són conductores elèctricament. Es van preparar diferents composicions utilitzant resina glicidil bisfenol-A epoxi, trietilenetetramina, policaprolactona, nanotubs de carboni i es destaquen els problemes per obtenir una qualitat d’impressió adequada. Les mostres impreses es van estudiar en termes de conductivitat elèctrica estudiant la conductivitat elèctrica de corrent altern i directe. El sistema material s’explora quant al nivell de reticulació, l’estructura i la morfologia i el comportament tèrmic. Es presenta un model per als nanocomposites mitjançant dades d’impedància obtingudes mitjançant l’espectroscòpia dielèctrica de banda ampla. La impressora s’utilitzarà en un futur per imprimir dispositius funcionals a petita escala, inclosos dispositius d’emmagatzematge d’energia, p. bateries d’estat sòlid, supercondensadors i plaques d’elèctrodes per a aquest tipus de dispositius.La fabricación aditiva (AM) es un proceso de fabricación de capas sucesivas de material para construir un objeto sólido tridimensional a partir de un modelo digital, a diferencia de las metodologías de fabricación sustractiva. AM ofrece la libertad de diseñar e innovar un producto para que se puedan obtener y revisar piezas complejas si es necesario, en un tiempo reducido en comparación con las tecnologías de fabricación tradicionales. En términos de su utilización total y generalizada, la tecnología tiene aplicaciones limitadas. Por motivos similares, la nanotecnología se considera la fuerza impulsora detrás de una nueva revolución industrial. Tiene la capacidad de incorporar funcionalidades específicas, que se producen debido a la escala nanométrica, a las partes deseadas para dispositivos funcionales como electrodos para dispositivos de almacenamiento de energía. La tesis se centra en el uso de nanocompuestos conductores de electricidad en la fabricación aditiva. En este escenario, dos tipos de nanocompuestos están preparados para usar como materia prima para la impresión de nanocompuestos conductores de electricidad que emplean dos tipos diferentes de material matricial; (1) un polímero termoplástico y (2) una resina termoestable. Los nanotubos de carbono se usaron como partículas de nanoestructura eléctricamente conductoras. Estas nanoestructuras forman redes complejas en una matriz polimérica de manera que el material de la matriz se transforma de un material aislante en un material eléctricamente conductor. La policaprolactona es un polímero semicristalino y se considera un material matriz adecuado entre la clase de polímeros termoplásticos, ya que ofrece excelentes características reológicas, de flujo y elásticas. Los hilos se imprimieron usando una extrusora biológica y se midió la conductividad eléctrica en estos hilos bajo el efecto de la deformación uniaxial. La microestructura cambia bajo el efecto de una deformación uniaxial que conduce a alterar la orientación de los nanotubos de carbono en la matriz de policaprolactona. Como consecuencia de la realineación de los nanotubos, las vías conductoras interrumpen u organizan, lo que puede aumentar o disminuir la conductividad eléctrica en los nanocompuestos. Las radiaciones de sincrotrón se utilizan para sondear tales cambios en la microestructura. Se prepararon diferentes composiciones usando nanotubos de carbono y las muestras impresas se estudiaron en términos de conductividad eléctrica y microestructura usando radiaciones sincrotrónicas. Basado en el análisis, se propone un modelo que puede predecir la conductividad eléctrica bajo el efecto de la deformación uniaxial. En términos de polímeros termoestables, se introduce un sistema simple para la impresión de nanocompuestos termoestables a base de polímeros. El detalle completo del sistema de impresión y la tinta de nanocompuestos se proporciona en uno de los capítulos. La tinta de nanocompuesto a base de epoxi se preparó para contener nanotubos de carbono como partículas de relleno con una pequeña porción de polímero termoplástico, policaprolactona. Las muestras impresas están sujetas al sesgo externo que indica que son eléctricamente conductoras. Se prepararon diferentes composiciones usando resina epoxi de glicidil bisfenol-A, trietilentetramina, policaprolactona, nanotubos de carbono y se resaltan los problemas para adquirir la calidad de impresión adecuada. Las muestras impresas se estudiaron en términos de conductividad eléctrica, estudiando la conductividad eléctrica de corriente alterna y continua. El sistema de materiales se explora en términos del nivel de reticulación, estructura y morfología y comportamiento térmico. Se presenta un modelo para los nanocompuestos utilizando datos de impedancia obtenidos mediante espectroscopía dieléctrica de banda ancha. La impresora se utilizará en el futuro para imprimir dispositivos funcionales a pequeña escala, incluidos dispositivos de almacenamiento de energía.
Additive manufacturing is a process of making successive layers of material to build a three-dimensional solid object from a digital model, as opposed to subtractive manufacturing methodologies. This technology offers the freedom to design and innovation of a product so that complex parts can be obtained and revise if needed, within a small time as compared to traditional manufacturing technologies. In terms of its full utilization and widespread, the technology has limited applications. On similar grounds, nanotechnology is considered as the driving force behind a new industrial revolution. It has the ability to incorporate specific functionalities, occur due to the nanometric scale, to desired parts that offer freedom to design functional devices like electrodes for energy storage devices. The thesis is focusing on the use of electrically conductive nanocomposites into additive manufacturing. In this scenario, two types of nanocomposites are prepared to use as raw material for printing of electrically conductive nanocomposites employing two different types of matrix material; (1) a thermoplastic polymer and (2) a thermoset resin. Carbon nanotubes were used as electrically conductive nanostructure particles. These nanostructures form complex networks into a polymer matrix such that the matrix material transforms from an insulative material into an electrically conductive material. Polycaprolactone is a semicrystalline polymer and it is considered suitable matrix material amongst the class of thermoplastic polymers as it offers excellent rheological, flow and the elastic characteristics. Strands were printed using a bio extruder and electrical conductivity was measured in these strands under the effect of uniaxial deformation. The microstructure changes under the effect of uniaxial deformation leading to alter the orientation of carbon nanotubes in the polycaprolactone matrix. As a consequence of realignment of nanotubes, conductive pathways either disrupt or organize which can increase or decrease an electrical conductivity in the nanocomposites. Synchrotron radiations are used to probe such changes in the microstructure. Two different compositions were prepared using carbon nanotubes and the printed samples are studied in terms of electrical conductivity and microstructure using synchrotron radiations. Based on the analysis, a model is proposed that can predict the orientation of carbon nanotubes under the effect of uniaxial deformation. In terms of thermoset polymers, a simple system is introduced for the printing of thermoset polymer (epoxy) based nanocomposites. Complete detail of the printing system is provided in one of the chapters. Epoxy-based nanocomposite ink was prepared to contain carbon nanotubes as filler particles with a small portion of thermoplastic polymer, polycaprolactone. The printed samples are subject to the external bias which indicate that these are electrically conductive. A complete methodology was provided for the preparation of nanocomposite ink. Different compositions were prepared using glycidyl bisphenol-A epoxy resin, triethylenetetramine, polycaprolactone, carbon nanotubes and issues are highlighted to acquire appropriate print quality. The printed samples were studied in terms of electrical conductivity studying alternating and direct current electrical conductivity. The material system is explored in terms of the level of crosslinking, structure and morphology and thermal behaviour. A model is presented for the nanocomposites using impedance data obtained through broadband dielectric spectroscopy. The printer will be used in future to print small scale functional devices including energy storage devices e.g. solid-state batteries, supercapacitors and electrode plates for such kind of devices.
Universitat Autònoma de Barcelona. Programa de Doctorat en Ciència de Materials
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Ng, Yean Thye. "Electrically conductive melt-processed blends of polymeric conductive additives with styrenic thermoplastics." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/11016.
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The growing demand in portable and compact consumer devices and appliances has resulted in the need for the miniaturisation of electronic components. These miniaturised electronic components are sensitive and susceptible to damage by voltages as low as 20V. Electrically conductive styrenic thermoplastics are widely used in electronic packaging applications to protect these sensitive electronic components against electro-static discharge (ESD) during manufacturing, assembly, storage and shipping. Such ESD applications often require the optimal volume resistance range of ≥ 1.0x105 to < 1.0x108 Ω. The best known method to render styrenic thermoplastics conductive is by the incorporation of conductive fillers, such as carbon black but the main limitation is the difficulty in controlling the conductivity level due to the steep percolation curve. Thus the aim of this research is to develop electrically conductive styrenic thermoplastics by blending several styrenic resins with polymeric conductive additives to achieve optimal volume resistance range for ESD applications with the ease in controlling the conductivity level.
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Javaid, Salman. "Some aspects of ionic liquid blends and additives influencing bulk conductivity of commercial base paper." Thesis, Karlstads universitet, Avdelningen för kemiteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-26775.
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In this study, bulk conductivity of commercial base paper impregnated with different ionic liquids blends and additives, through bench coating was investigated. Bulk conductivity of base paper, ion conductive paper and surface sized ion conductive papers with and without the influence of calendering were evaluated at different concentrations of ionic liquids using at resistivity cell and four point probe technique. It was shown that bulk conductivity of base paper was increased by increasing the amount of ionic liquids. Nano fibril cellulose also showed positive influence on the bulk conductivity of coated papers. By increasing the line load in the calendering machine, a positive influence on the bulk conductivity was observed. The tensile index of all the coated papers was lower than that of the base paper.
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Nilssen, Benedicte Eikeland. "Stability of Conductive Carbon Additives for High-voltage Li-ion Battery Cathodes." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26847.
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Conductive carbon additives are important constituents of the current state-of-the-art Li-ion battery cathodes, as the traditional active cathode materials are characterized by too low electronic conductivities. In high-voltage Li-ion batteries, these additives are subject for anion intercalation and electrolyte oxidation, which might cause changes in the conductive carbon network in the cathode, and hence the overall cycling performance of the electrode. This thesis has focused on study the stability of three types of carbon additives operating at high voltages. Materials included were two conventional types of conductive additives, graphite, KS6, and carbon black, Super P Li, both provided from TIMCAL. In addition, a multilayer graphene powder, Graphene AO-2, provided from Graphene Supermarket has been investigated. The powder properties, size, shape and structure, were studied in a scanning electron microscope and by powder X-ray diffraction. Electrodes from these materials were cycled galvanostatically and with cyclic voltammetry to reveal their high-voltage behaviour, with respect to the two above mentioned electrochemical processes. More detailed investigations of anion intercalation in KS6 and Graphene AO-2 were conducted by in situ X-ray diffraction measurements and scanning electron microscopy. For cycling in 30:70 vol% EC/DMC 1 M LiPF6 to a voltage of 4.7 V vs. Li+/Li, the results showed that Super P Li can be considered as the most stable conductive additive. At 4.7 V vs. Li+/Li, both KS6 and Graphene AO-2 are electrochemically active, while Graphene AO-2 displays a more reversible behavior, and are more stable than KS6. For even higher operation potential, 5.0 V vs. Li+/Li, Graphene AO-2 showed the least stable behavior of the three materials, due to large degree of electrolyte oxidation, unstable anion intercalation upon continuous cycling, and the suggestions of structural degradation of the electrode. However, a small increase in the electrolyte stability window was shown with Graphene AO-2 when changing to a more viscous electrolyte (1:1 vol% EC/DMC 1 M LiPF6) or adding an anion receptor (tris(hexafluoroisopropyl)borate) to the electrolyte. The anion intercalation in KS6 was observed to form staged phases, starting at 4.83 V vs. Li+/Li. The electrode structure was suggested to be affected in a smaller extent compared to Graphene AO-2. In addition, less electrolyte was oxidized at the KS6 electrode surface, compared to the two other materials. However, the film formed on the Super P Li electrodes did not seem to affect the carbon negatively, because stable anion intercalation was observed upon continuous cycling. Indicating that Super P Li was not strongly affected by the intercalation process.
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Myers, Philip D. Jr. "Additives for Heat Transfer Enhancement in High Temperature Thermal Energy Storage Media: Selection and Characterization." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5749.
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Inorganic salts are very promising as high-temperature heat transfer fluids and thermal storage media in solar thermal power production. The dual-tank molten salt storage system, for example, has been demonstrated to be effective for continuous operation in solar power tower plants. In this particular storage regime, however, much of the thermal storage potential of the salts is ignored. Most inorganic salts are characterized by high heats of fusion, so their use as phase-change materials (PCMs) allows for substantially higher energy storage density than their use as sensible heat storage alone. For instance, use of molten sodium-potassium eutectic salt over a temperature range of 260 to 560°C (the approximate operating parameters of a proposed utility-scale storage system) allows for a volumetric energy storage density of 212 kWhth/m3, whereas the use of pure sodium nitrate (T_m = 307°C) over the same temperature range (utilizing both sensible and latent heat) yields a storage density of 347 kWhth/m3.
The main downside to these media is their relatively low thermal conductivity (typically on the order of 1 W/m-K). While low conductivity is not as much an issue with heat transfer fluids, which, owing to convective heat transfer, are not as reliant on conduction as a heat transfer mode, it can become important for PCM storage strategies, in which transient charging behavior will necessarily involve heating the solid-phase material up to and through the process of melting. This investigation seeks to develop new methods of improving heat transfer in inorganic salt latent heat thermal energy storage (TES) media, such as sodium / potassium nitrates and chlorides. These methods include two basic strategies: first, inclusion of conductivity-enhancing additives, and second, incorporation of infrared absorptive additives in otherwise transparent media. Also, in the process, a group of chloride based salts for use as sensible storage media and/or heat transfer fluids has been developed, based on relevant cost and thermophysical properties data.
For direct conductivity enhancement, the idea is simple: a PCM with low conductivity can be enhanced by incorporation of nanoparticulate additives at low concentration (~5 wt %). This concept has been explored extensively with lower temperature heat transfer fluids such as water, ethylene glycol, etc. (e.g., nanofluids), as well as with many lower temperature PCMs, such as paraffin wax. Extension of the concept to high temperature inorganic salt thermal storage media brings new challenges—most importantly, material compatibility. Also, maintenance of the additive distribution can be more difficult. Promising results were obtained in both these regards with nitrate salt systems.
The second heat transfer enhancement strategy examined here is more novel in principle: increasing the infrared absorption of a semitransparent salt PCM (e.g., NaCl) with a suitable additive can theoretically enhance radiative heat transfer (for sufficiently high temperatures), thereby compensating for low thermal conductivity. Here again, material compatibility and maintenance of additive dispersion become the focus, but in very different ways, owing to the higher temperatures of application (>600°C) and the much lower concentration of additives required (~0.5 wt %). Promising results have been obtained in this case, as well, in terms of demonstrably greater infrared absorptance with inclusion of additives.
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Oja, Thomas Edward. "Characterization of the Integration of Additively Manufactured All-Aromatic Polyimide and Conductive Direct-Write Silver Inks." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/101036.
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Hybridizing additive manufacturing (AM) structures and direct write (DW) deposition of conductive traces enables the design and physical creation of integrated, complex, and conformal electronics such as embedded electronics and complex routing on a fully AM structure. Although this hybridization has a promising outlook, there are several key AM substrate-related limitations that limit the final performance of these hybridized AM-DW electronic parts. These limitations include low-temperature processability (leading to high trace resistivity) and poor surface finish (leading to electronic shorts and disconnections). Recently discovered ultraviolet-assisted direct ink write (UV-DIW) all-aromatic polyimide (PI) provides an opportunity to address these previous shortcomings previously due to its high-temperature stability (450C) and superior surface finish (relative to other AM processes).
The primary goal of this thesis is to characterize the integration of this UV-DIW PI with DW-printed conductive inks as a means for obtaining high-performance hybrid AM-DW electronics. This goal has been achieved through an investigation into the increased temperature stability of AM PI on the conductivity and adhesion of DW extrusion and aerosol jet (AJ) silver inks, determining the dielectric constant and dissipation factor of processed UV-DIW PI, and determining the achievable microwave application performance of UV-DIW PI. These performance measurements are compared to commercially-available PI film and relative to existing AM substrates, such as ULTEM 1010.
The temperature stability of UV-DIW PI enabled higher-temperature post-processing for the printed silver traces, which decreased DIW trace resistivity from 14.94±0.55 times the value of bulk silver at 160 °C to 2.16±0.028 times the resistivity of bulk silver at 375 °C, and AJ silver trace resistivity from 5.27±0.013 times the resistivity of bulk silver at 200 °C to 1.95±0.15 times the resistivity of bulk silver at 350 °C. The adhesion of these traces was not negatively affected by higher processing temperatures, and the traces performed similarly on UV-DIW PI and commercial PI. Furthermore, at similar thicknesses, UV-DIW PI was found to have a similar dielectric constant and dissipation factor to commercial Dupont Kapton PI film from 1 kHz to 1 MHz, indicating its ability to perform highly as a dielectric electronics substrate. Finally, the decrease in resistivity was able to decrease the gap in microwave stripline transmission line performance when compared with ULTEM 1010 processed at 200°C, with peak 10 GHz S21 loss differences decreasing from 2.46 dB to 1.32 dB after increasing the UV-DIW processing temperature from 200 °C to 400°C.Master of Science
Due to the extensive potential benefits and applications, researchers are looking to hybridize additive manufacturing (AM) processes with direct write (DW) techniques to directly print a 3D part with integrated electronics. Unfortunately, there are several key substrate-related limitations that hinder the overall performance of a part fabricated by hybrid AM-DW processes. Specifically, typical AM materials are not capable of providing an electronics substrate with combined sufficient surface resolution, surface finish, and high-temperature processing stability. However, the recent discovery of a novel AM-processable all-aromatic polyimide (PI) presents an opportunity for addressing these limitations as its printed form offers a high surface resolution, superior surface finish, and mechanical stability up to 400 °C. The primary goal of this thesis is to evaluate the benefits and drawbacks of this PI, processed via ultraviolet-assisted direct ink write (UV-DIW) AM, as an AM-DW electronics substrate. Specifically, the author characterized the effect of the increased temperature stability of the printed PI on the resultant conductivity and adhesion of silver inks printed via direct ink write (DIW) and aerosol jetting (AJ) DW processes. These results were also compared to the performance of the inks on commercial PI. Furthermore, the dielectric performance of printed PI was evaluated and compared to commercial PI. To demonstrate and evaluate the hybridized approach in a potential end-use application, the author also characterized the achievable microwave application performance of UV-DIW polyimide relative to the existing highest performance commercially available printed substrate material. The experiments in this thesis found an 83% and 66% decrease in resistivity from extrusion and AJ printed inks due to the ability of the printed PI to be processed at higher temperatures. Furthermore, UV-DIW PI was found to have similar dielectric properties to commercial PI film, which indicates that it can serve as a high-performance dielectric substrate. Finally, the high-temperature processing stability was able to decrease the performance gap in microwave application performance between the higher performing dielectric substrate, ULTEM 1010. These results show that UV-DIW could serve as a dielectric substrate for hybridized AM-DW electronic parts with higher performance and the ability to be deployed in harsher environments than previous AM-DW electronic parts explored in literature.
Books on the topic "Additifs de conduction"
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John, Murphy. The additives for plastics handbook: Antioxidants, antistatics, compatibilisers, conductive fillers, flame-retardants, pigments, plasticisers, reinforcements : classification, data, tables, descriptions, market trends, suppliers/brand names. Oxford, UK: Elsevier Advanced Technology, 1996.
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Durrant, Colin. The Framing of Choirs and Their Conductors. Edited by Frank Abrahams and Paul D. Head. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199373369.013.12.
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The British choral tradition is rooted in its ancient cathedrals and chapels, where the office of Evensong is sung, often daily. In addition, choral societies are to be found in most localities where singers come together and perform some of the major works in the western canon. Although singing itself occurs in a variety of forms this chapter looks at conductor-led choral singing. It does not give a fulsome picture of UK choral conducting and singing. Nonetheless, through a brief history starting from the John Curwen’s tonic sol-fa ideas for singing and culminating in a 20th century choral music renaissance; through an analysis of the English choral tradition; through a consideration of revivals of UK singing such as “Sing Up”; and through questionnaires and interviews with conductors and singers, the chapter explores some of the personal, cultural and sociological, educational, and musical issues and interests that can be found in the United Kingdom now.
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Abrahams, Daniel. Fostering Musical and Personal Agency. Edited by Frank Abrahams and Paul D. Head. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199373369.013.6.
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With the goal to create personal and musical agency in choral conductors, this chapter discusses the application of constructivist principles to choral pedagogy and the teaching of an undergraduate conducting class. In addition to teaching the requisite conducting skills, reflective practice, meaning making, and problem solving were included to foster habits of mind to prepare students to eventually conduct their own ensembles. Undergraduate students in their first conducting class provided the data, which included reflective journals, in class feedback, along with the teacher’s reflective memos. The chapter describes how conducting students navigated the challenges that called upon their previous experiences as ensemble members and their prior musical knowledge. In the end, conducting students expressed feelings of confidence and empowerment that suggested they had achieved both musical and personal agency.
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Katirji, Bashar. Specialized Electrodiagnostic Studies. Edited by Bashar Katirji. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190603434.003.0003.
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In addition to nerve conduction nerve studies and needle EMG, the clinical EMG study include more specialized examinations Some of the tests, such as the F waves and H reflexes are now often used as part of the routine nerve conduction studies. Others are utilized for specific indications: Repetitive nerve stimulation and single fiber EMG are used predominantly in patients with suspected neuromuscular junction disorders such as myasthenia gravis, Lambert-Eaton myasthenic syndrome or botulism; the blink reflexes are used in patients with disorders of the facial and trigeminal nerves as well as brainstem conditions. This chapter covers the late responses, including the F waves, H reflexes and blink reflexes and their applications in the diagnosis of peripheral nerve disorders. This is a followed by a discussion of the basic concepts of slow and rapid repetitive nerve stimulation and single fiber EMG, as well as their applications in the diagnosis of neuromuscular junction disorders.
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Enns, Charlotte. Making the Case for Case Studies in Deaf Education Research. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190455651.003.0010.
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When done well, case studies can provide rigorous and powerful evidence. This chapter provides a definition of case studies and outlines the process of conducting case study research in five stages: (1) determining the research questions, (2) designing the study (case selection and preparation), (3) collecting the data, (4) analyzing the data, and (5) reporting on the findings. In addition, the ways that case studies are uniquely suited to addressing particular questions in the field of deaf education are addressed. The contributions and benefits of conducting case studies to promote strength-based perspectives rather than deficit-model views of deaf students are highlighted throughout the chapter.
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Siebert, Stefan, Sengupta Raj, and Alexander Tsoukas. Complications of axial spondyloarthritis. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198755296.003.0009.
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In addition to the well-recognized extra-articular manifestations (EAMs) of ankylosing spondylitis (AS), this condition can also be associated with a number of clinically important complications. While EAMs are considered part of the spondyloarthritis (SpA), the complications are generally a consequence of having the disease. Patients with AS are at increased risk of osteoporosis and spinal fractures. The latter may occur after seemingly minor trauma and may lead to significant neurological compromise. Other potential neurological complications include atlantoaxial subluxation and compressive radiculopathy or myelopathy. Cardiac complications include cardiovascular events, valvular disease, and conduction disturbances. Pulmonary disease in AS relates to parenchymal involvement or mechanical constraint from chest wall inflammation. Renal disease is generally rare in AS.
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Burns, Tom, and Mike Firn. The role of medication. Edited by Tom Burns and Mike Firn. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198754237.003.0007.
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This chapter focuses mainly on the importance of maintenance antipsychotic medication and mood stabilizers. It examines procedures to support persistence with these drugs and maintain engagement. The techniques for initiating and monitoring clozapine therapy in the community for patients with resistant schizophrenia are outlined. The practical processes for ensuring and conducting regular structured reviews of long-term medication, both to assess progress and to identify side effects, are described in detail. In addition, the judicious use of antidepressants and benzodiazepines is outlined.
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Mirza-Babaei, Pejman. Reporting user research findings to the development team. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198794844.003.0018.
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As part of conducting research, reporting must occur. In addition to communicating the research result accurately, a report must motivate the team to act on the result, which often means modifying their build to increase the quality of their product. Approaches used to report user research findings back to the development team are just as important as the findings themselves. If the findings are not communicated to the development team effectively, the developers may not take action and miss potentially critical changes that could have made a difference in the development cycle and overall success of the project. If user researchers conduct the best possible study, identify the most critical issues, but fail to communicate or explain the findings in a way that motivates the development team, then changes may not occur. Many chapters in this book discuss methodologies for conducting user research; this chapter focuses on approaches to communicate the findings to the development team.
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Head, Paul D. The Choral Experience. Edited by Frank Abrahams and Paul D. Head. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199373369.013.3.
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Much has changed in the choral rehearsal room over the past two generations, particularly in regard to the role the choral conductor assumes—or commands—in the rehearsal process. This chapter discusses the ever-evolving stereotypical roles of the conductor, while examining alternatives to traditional leadership models with particular emphasis on the encouragement of student engagement and peer-based learning. In addition to the facilitation of collaborative learning exercises, the chapter outlines a specific process of written interaction with the choral ensemble. This section is inspired by the renowned “Dear People” letters of Robert Shaw. Finally, in response to the recently revised National Standards for Music Education in the United States, the author discusses possible implementation of the Standards in a performance-based classroom. In the shadow of the relatively recent phenomena of collegiate a cappella groups, these student ensembles have created a new paradigm for peer-led instruction.
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Hultaker, Annette. Transparent Conductive Tin Doped Indium Oxide: Characterization of Thin Films Made by Sputter Deposition With Silver Additive & by Spin Coating from Nanoparticle ... the Faculty of Science & Technology, 37). Uppsala Universitet, 2002.
Find full textBook chapters on the topic "Additifs de conduction"
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Bandara, Asoka J. "Conducting fillers for plastics: (2) Conducting polymer additives." In Plastics Additives, 180–88. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5862-6_21.
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Zilles, Joerg Ulrich. "Thermally Conductive Additives." In Encyclopedia of Polymers and Composites, 1–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-37179-0_37-1.
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Zilles, Joerg Ulrich. "Thermally Conductive Additives." In Encyclopedia of Polymers and Composites, 1–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-37179-0_37-2.
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Zilles, Joerg Ulrich. "Thermally Conductive Additives." In Polymers and Polymeric Composites: A Reference Series, 1–21. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-642-37179-0_37-3.
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Zilles, Joerg Ulrich. "Thermally Conductive Additives." In Fillers for Polymer Applications, 355–74. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-28117-9_37.
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Ollila, Richard G., and Donald M. Bigg. "Conducting fillers for plastics: (1) flakes and Fibers." In Plastics Additives, 170–79. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5862-6_20.
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Spahr, Michael E. "Carbon-Conductive Additives for Lithium-Ion Batteries." In Lithium-Ion Batteries, 1–38. New York, NY: Springer New York, 2008. http://dx.doi.org/10.1007/978-0-387-34445-4_5.
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Malekipour, Ehsan, Andres Tovar, and Hazim El-Mounayri. "Heat Conduction and Geometry Topology Optimization of Support Structure in Laser-Based Additive Manufacturing." In Mechanics of Additive and Advanced Manufacturing, Volume 9, 17–27. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-62834-9_4.
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Ayad, Mohamed M., K. Keiji Kanazawa, and J. C. Scott. "Film Thickness Control for Chemically Synthesized Conducting Polypyrrole." In Surface Phenomena and Additives in Water-Based Coatings and Printing Technology, 179–89. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4899-2361-5_14.
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Andrade, C., P. Garcés, F. J. Baeza, Ó. Galao, and E. Zornoza. "Electronic and Electrolytic Conduction of Cement Pastes with Additions of Carbonaceous Materials." In Durability of Reinforced Concrete from Composition to Protection, 11–25. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09921-7_2.
Full textConference papers on the topic "Additifs de conduction"
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Safavisohi, Babak, Ehsan Sharbati, Cyrus Aghanajafi, and Seyed Reza Khatami Firoozabadi. "Transient Radiative Heat Transfer Analysis of a Polypropylene Layer Using Hottel’s Zonal Method." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95438.
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Polymer films possess excellent optical properties, such as high transparency, and thermal characteristics, like low heat conductivity, as well as further polymer specific advantages. Consequently, polymer films have an outstanding potential for many solar applications. They are already used for encapsulation of photovoltaic (PV) cells, as convection barrier in solar collectors and as substrate or adhesive layers for glazing. In translucent polymers, energy can be transferred internally by radiation in addition to conduction. Since radiant propagation is very rapid, it can provide energy within the layer more quickly than diffusion by heat conduction. Thus, the transient thermal response of a layer for combined radiative and conduction may be extremely different from that of conduction alone. In this paper, the behavior of a heat conducting, absorbing, and emitting layer of Polypropylene is investigated during the transient interval when both conductive and radiative heat transfer are considered. The governing differential equations include the equation of radiative heat transfer within the material coupled to the transient energy equation, which contains both radiative and conductive terms. The solution procedure is based on nodal analysis and Hottel’s zonal method extended by the ray tracing method. The transient energy equation including the radiative internal energy source is solved using a time marching finite difference procedure with variable space and time increments. In addition, effects of variable parameters including optical thickness and thermal conductivity of the layer are investigated carefully.
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Demidenko, Natalia, Artem Kuksin, Denis Murashko, Nadezda Cherepanova, Anna Semak, Vladislav Bychkov, Alexey Komarchev, et al. "Laser formation of electrically conductive nanocomposites for bioelectronic applications." In 3D Printed Optics and Additive Photonic Manufacturing II, edited by Georg von Freymann, Alois M. Herkommer, and Manuel Flury. SPIE, 2020. http://dx.doi.org/10.1117/12.2564679.
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Hille, Carmen, Wolfgang Lippmann, Marion Herrmann, and Antonio Hurtado. "Non-Oxide Ceramics: Chances for Application in Nuclear Hydrogen Production." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48408.
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Research and development are increasingly focusing on the provision and utilization of heat in the high-temperature range above 900 °C, in particular under the aspect of resource-saving energy technologies. On the one hand, the exploitation of the high-temperature range helps to improve the efficiency of energy conversion processes; on the other hand, the provision of high-temperature heat makes it possible to utilize innovative thermochemical processes, which in turn represent environmentally compatible processes. An example to be quoted here is the thermally induced production of hydrogen by the iodine-sulfur process. The high temperatures alone place extremely high requirements on the materials to be used so that metallic materials soon reach their limits of application. If additionally chemically aggressive process media are used, as in the iodine-sulfur process, basically only ceramic materials can be considered as construction materials. In this application, notably silicon carbide (SiC) is favored owing to its excellent high-temperature properties. The possible technical fields of application of such high-performance ceramics can be broadly extended provided that suitable, highly efficient joining methods are available for these ceramics. In addition to its use as a constructional ceramic, SiC can principally also be used as a functional ceramic. For this purpose, the basic ceramic is modified with different additives, providing it with electrical properties that permit its application as a full ceramic heat conductor or sensor. In this case, it also holds true that a suitable joining method for making electrically conductive joints will extend the fields of application considerably. Laser-based joining technologies are being developed for both applications at the Dresden University of Technology. The research work presented here notably focuses on laser joining of electrically conductive SiC ceramics. In addition to a CO2 laser, a diode laser has been used. Basically, electrical connection has been made in two ways. In the first variants, graphite pins are inserted into the joining zone as electrically conductive bridges. In an alternative concept, the oxidic glass filler itself is made electrically conductive with additives. Like that a full ceramic heating conductor joined by means of laser radiation has been tested. The temperature resistance and functionality of the laser-joined heating conductor could be fully demonstrated.
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Martinez, Andrew, and Jacob Brouwer. "Monte Carlo Investigation of Particle Properties Affecting TPB Formation and Conductivity in Composite Solid Oxide Fuel Cell Electrode-Electrolyte Interfaces." In ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2009. http://dx.doi.org/10.1115/fuelcell2009-85191.
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A previously-developed microstructure model of the Solid Oxide Fuel Cell (SOFC) electrode-electrolyte interface has been applied to the study of particle properties in these devices through the use of the Monte Carlo simulation method. Previous findings that have demonstrated the necessity of accounting for the gaseous phase percolation have been re-emphasized through the current investigation. In particular, the effects of three-phase percolation critically affect the dependence of TPB formation and electrode conductivity on: 1) conducting phase particle size distributions, 2) electronic:ionic conduction phase contrast, and 3) the amount of Mixed Electronic-Ionic Conductor (MEIC) included in the electrode. In particular, the role of differing percolation effectiveness between electronic and ionic phases has been shown to counteract and influence the role of the phase contrast. Porosity, however, has been found to not be a significant factor for the range studied, but does not obviate the necessity of modeling the gas phase. In addition, the current work has investigated the inconsistencies in experimental literature results concerning the optimal particle size distribution. It has been found that utilizing smaller particles with a narrow size distribution is the preferable situation for electrode manufacturing. These findings stress the property-function relationships of fuel cell electrode materials.
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Chen, W., H. Jiang, Q. Zhang, and L. He. "A Simple Corner Correction Technique for Transient Thermal Measurement." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26622.
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The 1D conduction analytical and semi-analytical approaches for a semi-infinite domain have been widely adopted in the data processing of transient thermal experiments. The convective heat transfer coefficient (HTC) calculated by the 1D approach contains large errors when lateral conduction effects are significant, especially near a corner of solid domain. The problems could be addressed by alternative full 3D numerical conduction analyses, which tend to be complex as well as requiring extra experimental efforts to obtain the full thermal boundary conditions around corners, in addition to an access to a 3D conduction solver (CFD or FEA). In the present work, a simple and effective method is developed to correct such errors in the near-corner region without using any commercial tool. The present approach is based on the recognition that a temperature time trace in a 2D situation is the result of the accumulated heat conductions from the normal and lateral directions respectively and summatively. An equivalent semi-infinite 1D conduction temperature trace for a correct HTC can be generated by reconstructing and removing the lateral conduction effect at each discrete time step. This simple new correction procedure enables the standard 1D conduction analysis to be properly used to get the correct HTC, completely analytically without needing any aid of CFD or FEA solutions. Two test cases of practical interest with turbine blade tip heat transfer and film cooling are used for validation and demonstration. It has been consistently shown that the errors of the conventional 1D conduction analysis in the near corner regions can be greatly reduced by the new corner correction method. The demonstrated validity, the simplicity and robustness of the present method makes it a good candidate for future applications in transient thermal experimental studies.
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Kanazawa, Shusuke, Yasuyuki Kusaka, Ken-ichi Nomura, Noritaka Yamamoto, and Hirobumi Ushijima. "Fully additive manufacturing of a polymer cantilever with a conductive layer." In 2017 International Conference on Electronics Packaging (ICEP). IEEE, 2017. http://dx.doi.org/10.23919/icep.2017.7939420.
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MICHAEL, M. S., Y. R. SHAH, R. VIMALA, and S. R. S. PRABAHARAN. "CONDUCTIVE ADDITIVE CARBON FOR HIGH VOLTAGE ELECTROCHEMICAL DOUBLE LAYER CAPACITORS (EDLCs)." In Proceedings of the 8th Asian Conference. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812776259_0078.
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Sojoudi, Hossein, Fernando Reiter, and Samuel Graham. "Transparent Electrodes From Graphene/Single Wall Carbon Nanotube Composites." In ASME 2013 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ipack2013-73158.
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A transparent conductive electrode comprised of alternating layers of graphene grown by chemical vapor deposition (CVD) and metallic single wall nanotubes (M-SWNTs) is presented. It was found that the addition of two single-layer graphene sheets enhances the conduction pathways in the M-SWNT film, yielding up to a 75% decrease in the sheet resistance with little sacrifice in the optical transmittance. Enhancements in the electrical properties of the films were made through a heat treatment process followed by nitric acid and thionyl chloride doping, yielding a sheet resistance of 70 Ω/sq with a transmittance of 78% at 550 nm. Composite films having undergone an annealing step were found to have stable electrical properties upon exposure to atmospheric conditions while doped films demonstrated limited stability.
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Huang, Chyouhwu Brian, and Hung-Shyong Chen. "Heat Insulating Materials Thermal Conductivity Determination by Means of Comparison With a Standard Plate of Known Conductivity." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89382.
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Due to the soaring energy prices, the cost to maintain a basic living standard has increased, therefore choosing right insulated materials when building a new house/appliance is important. The heat transfer coefficient plays a vital role; therefore, developing an effective, accurate, and low cost testing machine is an important issue. This is also the goal of this research. The testing apparatus developed can be used to measure the thermal conductivity as a basis for the choice of the materials. The heat conduction testing equipment was designed using “the thermal conductivity comparison with a known conductivity” method in addition to the basic heat conduction theory. For the best results, several parameters were used to fine-tune the operating conductions, such as cooling flow rate, heat source temperature, etc. Three types of materials were used as the sample for verifying the accuracy of the developed apparatus: gypsum board, silicon cement and PE polyethylene foam. Four heat sources temperatures were tested: 30°C, 35°C, 40°C, and 45°C. Two cooling flow rates were used: 108 liter/hour and 90 liter/hour. In the end, ANSYS was used to validate the testing results. The testing results show that the measured thermal conductivity is accurate. Equilibrium can be reached faster when testing with high cooling flow rates. The best hot plate temperature is 30°C.
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Kajishima, Takeo, Katsuya Kondo, and Shintaro Takeuchi. "Numerical Simulation of Heat Transfer in Shear Flow of Liquid-Solid Two-Phase Media by Immersed Solid Approach." In ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-07513.
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We developed a direct numerical simulation (DNS) method of solid-fluid two-phase flows to study the effects of heat conductivity within a solid particle and the particle motion on the heat transfer. Heat transfer and particle behaviors were studied for different ratios of heat conductivity (solid to liquid) and solid volume fractions. The simulation results emphasize the effect of temperature distributions within the particles, and the heat transfer through each particle plays an important role for the motion of the particulate flow. The particle-laden flow in a two-dimensional channel of instable thermal stratification, namely hot wall at the bottom and cold wall at the top, is simulated. In the two-dimensional computation, the heat transfer attenuates by increasing the neutral conductive particles because of the resistance to the thermal convection. In case of highly conductive particles, the thermal convection and conductions are enhanced to some extent of addition but the overload of particles suddenly reduces the intensity of convection, resulting in the lower heat transfer. The inverse gradient of mean temperature is observed particularly in case of moderate loading of neutral conductive particles. It is due to the modulation of the profile of convection cells. Most of the above-mentioned findings are reproduced by the fully three-dimensional simulation.
Reports on the topic "Additifs de conduction"
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Jones, Robert M., Alison K. Thurston, Robyn A. Barbato, and Eftihia V. Barnes. Evaluating the Conductive Properties of Melanin-Producing Fungus, Curvularia lunata, after Copper Doping. Engineer Research and Development Center (U.S.), November 2020. http://dx.doi.org/10.21079/11681/38641.
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Melanins are pigmented biomacromolecules found throughout all domains of life. Of melanins’ many unique properties, their malleable electrically conductive properties and their ability to chelate could allow them to serve as material for bioelectronics. Studies have shown that sheets or pellets of melanin conduct low levels of electricity; however, electrical conductance of melanin within a cellular context has not been thoroughly investigated. In addition, given the chelating properties of melanin, it is possible that introducing traditionally con-ductive metal ions could improve the conductivity. Therefore, this study investigated the conductive properties of melanized cells and how metal ions change these. We measured the con-ductivity of pulverized Curvularia lunata, a melanized filamentous fungi, with and without the addition of copper ions. We then com-pared the conductivity measurements of the fungus to chemically synthesized, commercially bought melanin. Our data showed that the conductivity of the melanized fungal biomass was an order of magnitude higher when grown in the presence of copper. However, it was two orders of magnitude less than that of synthetic melanin. Interestingly, conductance was measurable despite additional constituents in the pellet that may inhibit conductivity. Therefore, these data show promising results for using melanized cells to carry electrical signals.
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Stoyanova-Ivanova, Angelina, Alexander Vasev, Peter Lilov, Violeta Petrova, Yordan Marinov, Antonia Stoyanova, Galia Ivanova, and Valdek Mikli. Conductive Ceramic Based on the Bi-Sr-Ca-Cu-O HTSC System as an Additive to the Zinc Electrode Mass in the Rechargeable Ni-Zn Batteries – Electrochemical Impedance Study. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, February 2019. http://dx.doi.org/10.7546/crabs.2019.02.05.
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Robayo Botiva, Diana María. Brief Current Context of the Types of Electronic Commerce in Colombia. Ediciones Universidad Cooperativa de Colombia, April 2021. http://dx.doi.org/10.16925/gclc.17.
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In the current context, e-commerce has improved significantly as consumers have increased online shopping in different sectors of the economy. Therefore, the term “e-commerce” is becoming increasingly well-known and relevant for conducting business transactions. In addition, the current context of the COVID-19 pandemic has contributed to the extreme growth of e-commerce, and in the long term it will be a vital part of companies to achieve a greater competitive advantage as it offers benefits to the end consumer. However, it is important to note that there will be technological and non-technological limitations that will affect its growth. Nevertheless, the advance of information and communication technologies (ICTS) will tend to correct these limitations, consolidating the generalized increase of e-commerce worldwide. Consequently, it is pertinent that students of economics, administrative and accounting sciences, engineering, among others, expand their knowledge in e-commerce and thus be at the forefront of the different issues surrounding the digital transformation in companies and the digital economy.
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Michalak, Julia, Josh Lawler, John Gross, and Caitlin Littlefield. A strategic analysis of climate vulnerability of national park resources and values. National Park Service, September 2021. http://dx.doi.org/10.36967/nrr-2287214.
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The U.S. national parks have experienced significant climate-change impacts and rapid, on-going changes are expected to continue. Despite the significant climate-change vulnerabilities facing parks, relatively few parks have conducted comprehensive climate-change vulnerability assessments, defined as assessments that synthesize vulnerability information from a wide range of sources, identify key climate-change impacts, and prioritize vulnerable park resources (Michalak et al. In review). In recognition that funding and planning capacity is limited, this project was initiated to identify geographies, parks, and issues that are high priorities for conducting climate-change vulnerability assessments (CCVA) and strategies to efficiently address the need for CCVAs across all U.S. National Park Service (NPS) park units (hereafter “parks”) and all resources. To help identify priority geographies and issues, we quantitatively assessed the relative magnitude of vulnerability factors potentially affecting park resources and values. We identified multiple vulnerability factors (e.g., temperature change, wildfire potential, number of at-risk species, etc.) and sought existing datasets that could be developed into indicators of these factors. To be included in the study, datasets had to be spatially explicit or already summarized for individual parks and provide consistent data for at least all parks within the contiguous U.S. (CONUS). The need for consistent data across such a large geographic extent limited the number of datasets that could be included, excluded some important drivers of climate-change vulnerability, and prevented adequate evaluation of some geographies. The lack of adequately-scaled data for many key vulnerability factors, such as freshwater flooding risks and increased storm activity, highlights the need for both data development and more detailed vulnerability assessments at local to regional scales where data for these factors may be available. In addition, most of the available data at this scale were related to climate-change exposures, with relatively little data available for factors associated with climate-change sensitivity or adaptive capacity. In particular, we lacked consistent data on the distribution or abundance of cultural resources or accessible data on infrastructure across all parks. We identified resource types, geographies, and critical vulnerability factors that lacked data for NPS’ consideration in addressing data gaps. Forty-seven indicators met our criteria, and these were combined into 21 climate-change vulnerability factors. Twenty-seven indicators representing 12 vulnerability factors addressed climate-change exposure (i.e., projected changes in climate conditions and impacts). A smaller number of indictors measured sensitivity (12 indicators representing 5 vulnerability factors). The sensitivity indicators often measured park or landscape characteristics which may make resources more or less responsive to climate changes (e.g., current air quality) as opposed to directly representing the sensitivity of specific resources within the park (e.g., a particular rare species or type of historical structure). Finally, 6 indicators representing 4 vulnerability factors measured external adaptive capacity for living resources (i.e., characteristics of the park and/or surrounding landscape which may facilitate or impede species adaptation to climate changes). We identified indicators relevant to three resource groups: terrestrial living, aquatic living (including living cultural resources such as culturally significant landscapes, plant, or animal species) and non-living resources (including infrastructure and non-living cultural resources such as historic buildings or archeological sites). We created separate indicator lists for each of these resource groups and analyzed them separately. To identify priority geographies within CONUS,...
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Manual for the classification of intervention best-practices with rural NEETs. OST Action CA 18213: Rural NEET Youth Network: Modeling the risks underlying rural NEETs social exclusion, December 2020. http://dx.doi.org/10.15847/cisrnyn.mn1.2020.12.
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targeting rural NEETs. In my opinion, this is the most outstanding contribution of this manual, and also an original one, considering that to date no other efforts have been made with the intention of developing a grid of how to describe interventions dealing with rural NEETs. This manual offers, therefore, valuable contributions for upcoming research efforts within and beyond RNYN, including: (a) a complete methodological framework for future case stu-dies; (b) practical tools to conduct field research than can be combined with many different methodological approaches (qualitative, mixed-methods, etc.); and, (c) strategic criteria for conducting research in complex settings such as community-based programs. In addition, this manual sets the necessary conditions to present evidence-based conclusions about programs targeting rural NEETs, further aiding policy-makers to opt for solutions that clearly produce better results. This manual would not have been possible without the efforts and best knowledge from its editorial team. Therefore, as the Chair of RNYN, but also in a more personal note, I would like to thank Claudia Petrescu, Emre Erdogan and Paul Flynn for the impeccable and rigorous way in which they conducted all the process. I would also like to thank the Working Group 2 mem-bers traversing many countries who contributed to this document.