Influence of the initial chemical conditions on the rational design of silica particles

The influence of the water content in the initial composition on the size of silica particles produced using the Stöber process is well known. We have shown that there are three morphological regimes defined by compositional boundaries. At low water levels (below stoichiometric ratio of water:tetraethoxysilane), very high surface area and aggregated structures are formed; at high water content (>40 wt%) similar structures are also seen. Between these two boundary conditions, discrete particles are formed whose size are dictated by the water content. Within the compositional regime that enables the classical Stöber silica, the structural evolution shows a more rapid attainment of final particle size than the rate of formation of silica supporting the monomer addition hypothesis. The clearer understanding of the role of the initial composition on the output of this synthesis method will be of considerable use for the establishment of reliable reproducible silica production for future industrial adoption

Basal Body Positioning Is Controlled by Flagellum Formation in Trypanosoma brucei

To perform their multiple functions, cilia and flagella are precisely positioned at the cell surface by mechanisms that remain poorly understood. The protist Trypanosoma brucei possesses a single flagellum that adheres to the cell body where a specific cytoskeletal structure is localised, the flagellum attachment zone (FAZ). Trypanosomes build a new flagellum whose distal tip is connected to the side of the old flagellum by a discrete structure, the flagella connector. During this process, the basal body of the new flagellum migrates towards the posterior end of the cell. We show that separate inhibition of flagellum assembly, base-to-tip motility or flagella connection leads to reduced basal body migration, demonstrating that the flagellum contributes to its own positioning. We propose a model where pressure applied by movements of the growing new flagellum on the flagella connector leads to a reacting force that in turn contributes to migration of the basal body at the proximal end of the flagellum

Development of Highly Repellent Silica Particles for Protection of Hemp Shiv Used as Insulation Materials

New bio-materials have recently gained interest for use in insulation panels in walls, but wider adoption by the building industry is hindered by their intrinsic properties. The fact that such materials are mainly composed of cellulose makes them combustible, and their hydrophilic surface presents a high water uptake, which would lead to faster biodegradation. A hydrophobic treatment with silica particles was successfully synthesised via Stöber process, characterised, and deposited on hemp shiv. The surface of hemp shiv coated several times with 45 and 120 nm particles were uniformly covered, as well as extensively water repellent. Those samples could withstand in humidity chamber without loss of their hydrophobic property and no sign of mould growth after 72 h of exposure

Non destructive monitoring of mechanical stress in concrete for the survey of nuclear power plants

Session 2-1 - NDE and NDT for Civil Engineering, paper QNDE2019-6837, 3 pagesInternational audienceTo prevent consequences of damage in case of accident, some barriers of pre-stressed concrete are included in the nuclear power plant structures. Hence, to insure the nuclear security, it is important to control these structures. The nuclear accident induces pressure and temperature increases. This case is studied in a French Project involving eight academic and industrial laboratories with skills in NDE (Non-Destructive Evaluation) methods. In this paper, we focus on the synthesis for the results with different techniques in relation with the evolution of stress in the structure. Experiments tests have been conducted on slabs 0.5 m x 0.25 m x 0.12 m submitted to compressive load, for one concrete mix formulated to be representative of nuclear containment. In situ NDE measurements have been done during a test simulating nuclear accident. These experiments were realized on the Vercors mock-up which is a 1/3 scaled concrete power plant (? 16 m x h 30 m cylinder, with 0.40 m thick walls) submitted to internal pressure up to 4 bars. This study includes electromagnetic techniques such as radar, capacitive, resistivity, permeability and ultrasonic measurements (impact echo, ultrasonic pulse velocity for volume and surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). Good agreements are observed between laboratory and in situ measurements. Industrial and research perspectives are presented

Surveillance non destructive de l'état du béton des enceintes de confinement des centrales nucléaires avec et sans précontrainte

International audienceLes enceintes de confinement en béton précontraint des centrales nucléaires jouent un rôle majeur de sécurité en cas d'accident pour préserver l’environnement de fuites radioactives. Pour assurer la sûreté des installations, il est important de contrôler régulièrement les structures dont le prolongement de la durée de vie est acté et d’estimer leur endommagement en cas d’accident. Un accident provoque des augmentations de pression et de température dans l’enceinte interne et donc une diminution de la contrainte et une augmentation de la température du béton. Dans le projet PIA ANR ENDE, huit universitaires et laboratoires industriels avec des compétences en Évaluation Non Destructive (END), ont étudié le potentiel et la pertinence d’utiliser des ENDs pour suivre l’état du béton en termes de contrainte, d’endommagement et de fissuration dans de telles conditions. Dans cette présentation, nous nous concentrons sur la synthèse des résultats obtenus avec différentes techniques ENDs. Des tests expérimentaux ont été réalisés en laboratoire sur des dalles de 0,5 m x 0,25 m x 0,12 m, saines ou endommagées thermiquement, sous différents chargements statiques en compression, pour une formulation de béton spécifique. De manière complémentaire, des mesures ENDs ont été effectuées in-situ pendant une épreuve enceinte jusqu’à une pression de 4 bars sur le moyen d’essai VeRCoRs, maquette à l'échelle 1/3 d’une enceinte de confinement double paroi (cylindre de diamètre égal à 16 m, de 30 m de hauteur avec des parois de 0,40 m d'épaisseur). Des mesures radar (GPR), capacitive, de résistivité, de perméabilité et des mesures ultrasonores (impact echo,ondes de surface, pulse echo, interférométrie des ondes de coda, acoustique non linéaire, etc.) ont été entreprises. De bons accords sont observés entre les mesures de laboratoire et celles in situ. Cette étude ouvre des perspectives industrielles et de recherche notamment en lien avec la fusion de données pour l’estimation quantitative de propriétés telles que la teneur en eau, la porosité, la perméabilité

Surveillance non destructive de l'état du béton des enceintes de confinement des centrales nucléaires avec et sans précontrainte

International audienceLes enceintes de confinement en béton précontraint des centrales nucléaires jouent un rôle majeur de sécurité en cas d'accident pour préserver l’environnement de fuites radioactives. Pour assurer la sûreté des installations, il est important de contrôler régulièrement les structures dont le prolongement de la durée de vie est acté et d’estimer leur endommagement en cas d’accident. Un accident provoque des augmentations de pression et de température dans l’enceinte interne et donc une diminution de la contrainte et une augmentation de la température du béton. Dans le projet PIA ANR ENDE, huit universitaires et laboratoires industriels avec des compétences en Évaluation Non Destructive (END), ont étudié le potentiel et la pertinence d’utiliser des ENDs pour suivre l’état du béton en termes de contrainte, d’endommagement et de fissuration dans de telles conditions. Dans cette présentation, nous nous concentrons sur la synthèse des résultats obtenus avec différentes techniques ENDs. Des tests expérimentaux ont été réalisés en laboratoire sur des dalles de 0,5 m x 0,25 m x 0,12 m, saines ou endommagées thermiquement, sous différents chargements statiques en compression, pour une formulation de béton spécifique. De manière complémentaire, des mesures ENDs ont été effectuées in-situ pendant une épreuve enceinte jusqu’à une pression de 4 bars sur le moyen d’essai VeRCoRs, maquette à l'échelle 1/3 d’une enceinte de confinement double paroi (cylindre de diamètre égal à 16 m, de 30 m de hauteur avec des parois de 0,40 m d'épaisseur). Des mesures radar (GPR), capacitive, de résistivité, de perméabilité et des mesures ultrasonores (impact echo,ondes de surface, pulse echo, interférométrie des ondes de coda, acoustique non linéaire, etc.) ont été entreprises. De bons accords sont observés entre les mesures de laboratoire et celles in situ. Cette étude ouvre des perspectives industrielles et de recherche notamment en lien avec la fusion de données pour l’estimation quantitative de propriétés telles que la teneur en eau, la porosité, la perméabilité

Non Destructive Evaluation of concrete material properties for nuclear power plant survey: results in the laboratory and on the VeRCoRS mock-up

NDE/NDT, Structural Materials Technology for Highways and Bridges (SMT) and the International Symposium on Non-Destructive Testing in Civil Engineering (NDT-CE) 2018, New Brunswick, ETATS-UNIS, 27-/08/2018 - 29/06/2018Pre-stressed concrete nuclear power plant containment vessel is the third barrier in case of an accident so that quantifying concrete properties with Non Destructive Evaluation (NDE) is a continuing goal. This includes the mapping of the following concrete properties: elastic modulus, water saturation, permeability. In addition, those measurements have to be challenged with the level of stress (which will be modified during an accident) possibly coupled with thermal induced damage. In the ANR French project 'Non Destructive Evaluation of containment nuclear plant structures' (ENDE) eight partners have carried out laboratory and in situ NDE measurements with the aim to compare and combine them to reach quantitative useful information about concrete conditions. In this paper we present a synthesis of the mains results obtained with classical and non-classical NDE methods. This includes electromagnetic techniques such as radar, capacitive measurements, resistivity measurements and ultrasonic measurements (impact echo, ultrasonic pulse velocity - in reflexion and transmission mode for longitudinal and transverse waves, surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). The laboratory experiments have been conducted on slabs 0.5 m x 0.25 m x 0.12 m, for one concrete mix formulated to be representative of nuclear containment walls, in different conditions: - sound concrete without any stress for different water saturations,- heat damage of partially saturated slab (at 80°C, 150°C, 200°C),- sound concrete under stress (up to 30% of the compressive strength),- heat damage concrete under stress.A series of NDE method combinations (using data fusion approach) is performed to solve the problem of multiple sensitivity issues. This laboratory work is then transposed on the VeRCoRS mock-up which is a 1/3 scaled concrete power plant (a Õ 16 m x h 30 m cylinder, with 0.40 m thick walls) heavily instrumented (700 sensors, 2 km of fiber optic). In this paper we present results obtained before, during and after a decennial test simulation which consists in increasing the internal pressure with air, maintaining its level to 4 bars during 2 hours and then decreasing back to the atmospheric pressure level.To conclude industrial and research perspectives are presented.Pre-stressed concrete nuclear power plant containment vessel is the third barrier in case of an accident so that quantifying concrete properties with Non Destructive Evaluation (NDE) is a continuing goal. This includes the mapping of the following concrete properties: elastic modulus, water saturation, permeability. In addition, those measurements have to be challenged with the level of stress (which will be modified during an accident) possibly coupled with thermal induced damage. In the ANR French project 'Non Destructive Evaluation of containment nuclear plant structures' (ENDE) eight partners have carried out laboratory and in situ NDE measurements with the aim to compare and combine them to reach quantitative useful information about concrete conditions. In this paper we present a synthesis of the mains results obtained with classical and non-classical NDE methods. This includes electromagnetic techniques such as radar, capacitive measurements, resistivity measurements and ultrasonic measurements (impact echo, ultrasonic pulse velocity - in reflexion and transmission mode for longitudinal and transverse waves, surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). The laboratory experiments have been conducted on slabs 0.5 m x 0.25 m x 0.12 m, for one concrete mix formulated to be representative of nuclear containment walls, in different conditions: - sound concrete without any stress for different water saturations,- heat damage of partially saturated slab (at 80°C, 150°C, 200°C),- sound concrete under stress (up to 30% of the compressive strength),- heat damage concrete under stress.A series of NDE method combinations (using data fusion approach) is performed to solve the problem of multiple sensitivity issues. This laboratory work is then transposed on the VeRCoRS mock-up which is a 1/3 scaled concrete power plant (a Õ 16 m x h 30 m cylinder, with 0.40 m thick walls) heavily instrumented (700 sensors, 2 km of fiber optic). In this paper we present results obtained before, during and after a decennial test simulation which consists in increasing the internal pressure with air, maintaining its level to 4 bars during 2 hours and then decreasing back to the atmospheric pressure level.To conclude industrial and research perspectives are presented

Non Destructive Evaluation of concrete material properties for nuclear power plant survey: results in the laboratory and on the VeRCoRS mock-up

NDE/NDT for Highways & Bridges: SMT 2018, NEWAK, ETATS-UNIS, 27-/08/2018 - 29/06/2018Pre-stressed concrete nuclear power plant containment vessel is the third barrier in case of an accident so that quantifying concrete properties with Non Destructive Evaluation (NDE) is a continuing goal. This includes the mapping of the following concrete properties: elastic modulus, water saturation, permeability. In addition, those measurements have to be challenged with the level of stress (which will be modified during an accident) possibly coupled with thermal induced damage. In the ANR French project 'Non Destructive Evaluation of containment nuclear plant structures' (ENDE) eight partners have carried out laboratory and in situ NDE measurements with the aim to compare and combine them to reach quantitative useful information about concrete conditions. In this paper we present a synthesis of the mains results obtained with classical and non-classical NDE methods. This includes electromagnetic techniques such as radar, capacitive measurements, resistivity measurements and ultrasonic measurements (impact echo, ultrasonic pulse velocity - in reflexion and transmission mode for longitudinal and transverse waves, surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). The laboratory experiments have been conducted on slabs 0.5 m x 0.25 m x 0.12 m, for one concrete mix formulated to be representative of nuclear containment walls, in different conditions: - sound concrete without any stress for different water saturations,- heat damage of partially saturated slab (at 80°C, 150°C, 200°C),- sound concrete under stress (up to 30% of the compressive strength),- heat damage concrete under stress.A series of NDE method combinations (using data fusion approach) is performed to solve the problem of multiple sensitivity issues. This laboratory work is then transposed on the VeRCoRS mock-up which is a 1/3 scaled concrete power plant (a Õ 16 m x h 30 m cylinder, with 0.40 m thick walls) heavily instrumented (700 sensors, 2 km of fiber optic). In this paper we present results obtained before, during and after a decennial test simulation which consists in increasing the internal pressure with air, maintaining its level to 4 bars during 2 hours and then decreasing back to the atmospheric pressure level.To conclude industrial and research perspectives are presented

Non Destructive Evaluation of concrete material properties for nuclear power plant survey: results in the laboratory and on the VeRCoRS mock-up

NDE/NDT, Structural Materials Technology for Highways and Bridges (SMT) and the International Symposium on Non-Destructive Testing in Civil Engineering (NDT-CE) 2018, New Brunswick, ETATS-UNIS, 27-/08/2018 - 29/06/2018Pre-stressed concrete nuclear power plant containment vessel is the third barrier in case of an accident so that quantifying concrete properties with Non Destructive Evaluation (NDE) is a continuing goal. This includes the mapping of the following concrete properties: elastic modulus, water saturation, permeability. In addition, those measurements have to be challenged with the level of stress (which will be modified during an accident) possibly coupled with thermal induced damage. In the ANR French project 'Non Destructive Evaluation of containment nuclear plant structures' (ENDE) eight partners have carried out laboratory and in situ NDE measurements with the aim to compare and combine them to reach quantitative useful information about concrete conditions. In this paper we present a synthesis of the mains results obtained with classical and non-classical NDE methods. This includes electromagnetic techniques such as radar, capacitive measurements, resistivity measurements and ultrasonic measurements (impact echo, ultrasonic pulse velocity - in reflexion and transmission mode for longitudinal and transverse waves, surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). The laboratory experiments have been conducted on slabs 0.5 m x 0.25 m x 0.12 m, for one concrete mix formulated to be representative of nuclear containment walls, in different conditions: - sound concrete without any stress for different water saturations,- heat damage of partially saturated slab (at 80°C, 150°C, 200°C),- sound concrete under stress (up to 30% of the compressive strength),- heat damage concrete under stress.A series of NDE method combinations (using data fusion approach) is performed to solve the problem of multiple sensitivity issues. This laboratory work is then transposed on the VeRCoRS mock-up which is a 1/3 scaled concrete power plant (a Õ 16 m x h 30 m cylinder, with 0.40 m thick walls) heavily instrumented (700 sensors, 2 km of fiber optic). In this paper we present results obtained before, during and after a decennial test simulation which consists in increasing the internal pressure with air, maintaining its level to 4 bars during 2 hours and then decreasing back to the atmospheric pressure level.To conclude industrial and research perspectives are presented.Pre-stressed concrete nuclear power plant containment vessel is the third barrier in case of an accident so that quantifying concrete properties with Non Destructive Evaluation (NDE) is a continuing goal. This includes the mapping of the following concrete properties: elastic modulus, water saturation, permeability. In addition, those measurements have to be challenged with the level of stress (which will be modified during an accident) possibly coupled with thermal induced damage. In the ANR French project 'Non Destructive Evaluation of containment nuclear plant structures' (ENDE) eight partners have carried out laboratory and in situ NDE measurements with the aim to compare and combine them to reach quantitative useful information about concrete conditions. In this paper we present a synthesis of the mains results obtained with classical and non-classical NDE methods. This includes electromagnetic techniques such as radar, capacitive measurements, resistivity measurements and ultrasonic measurements (impact echo, ultrasonic pulse velocity - in reflexion and transmission mode for longitudinal and transverse waves, surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). The laboratory experiments have been conducted on slabs 0.5 m x 0.25 m x 0.12 m, for one concrete mix formulated to be representative of nuclear containment walls, in different conditions: - sound concrete without any stress for different water saturations,- heat damage of partially saturated slab (at 80°C, 150°C, 200°C),- sound concrete under stress (up to 30% of the compressive strength),- heat damage concrete under stress.A series of NDE method combinations (using data fusion approach) is performed to solve the problem of multiple sensitivity issues. This laboratory work is then transposed on the VeRCoRS mock-up which is a 1/3 scaled concrete power plant (a Õ 16 m x h 30 m cylinder, with 0.40 m thick walls) heavily instrumented (700 sensors, 2 km of fiber optic). In this paper we present results obtained before, during and after a decennial test simulation which consists in increasing the internal pressure with air, maintaining its level to 4 bars during 2 hours and then decreasing back to the atmospheric pressure level.To conclude industrial and research perspectives are presented