209 research outputs found
micro-XRCT data sets and in situ measured ultrasonic wave propagation of pre-stressed monodisperse rubber and glass particle mixtures with 10%, 20%, and 30% volume rubber content: samples 2 and 3
No full textThis dataset contains 12 micro X-ray Computed Tomography (micro-XRCT) data sets from scans of cylindrical particulate mixture samples (diameter 80 mm; unloaded height 80 mm) under different uniaxial compression loads. The samples consist of monodisperse stiff (glass) and soft (rubber) particle mixtures. Both particles have an identical diameter of 4 mm. The considered samples have a volume fraction of 10%, 20%, and 30% rubber particles. Two individual mixtures were investigated for each volume fraction. The scans were performed in a low X-ray absorbing transparent oedometer cell with an integrated pair of P-wave ultrasonic transducers to determine in situ the sample stiffness based on wave propagation velocity measurements. On both sides, the wave travels through a 10 mm long Poly (methyl methacrylate) (PMMA) pre-run and after-run section before and after the wave enters and leaves the sample.
The respectively prepared sample inside the oedometer cell was uniaxially compressed in axial direction in subsequent force increments from F_stat. = 200 N to F_stat. = 1000 N (force-controlled) using a Universal Testing Machine (UTM) integrated into the XRCT system. At each force level, the system was relaxed for some time at the defined force to compensate the creep behavior of the soft particles. Subsequently, ultrasonic wave propagation measurements were performed at five different load levels, F_stat. = {200, 400, 600, 800, 1000} N. micro-XRCT scans were acquired in situ at F_stat. = {400, 800} N. For this, it was switched from force-controlled to displacement-controlled to avoid creeping and an eventual movement of the particles during the imaging.
In this data set, the reconstructed 3d volumes ("mixture_nu*_F400N_reconstructed.tar.gz" and "mixture_nu*_F800N_reconstructed.tar.gz"), as well as the projection images ("mixture_nu*_F400N_projections.tar.gz" and "mixture_nu*_F800N_projections.tar.gz") with * indicating the rubber volume fraction nu = {0.1, 0.2, 0.3} and the mixture counter {2, 3} for both preloads are given. For the datasets with counter "1" see the related datasets. The raw ultrasonic measurement data (transducer signals over time) is provided for all five preloads ("mixture_nu*_ultrasonic_data.tar.gz"), before and after the force-controlled relaxation, as an averaged signal of a stack of 32 signals. The file "mixture_nu*_utm_data.csv" contains the measured axial force and displacement from the UTM during the whole experiment. Based on the measured displacement of the UTM, the current mixture length was determined
micro-XRCT data sets and in situ measured ultrasonic wave propagation of pre-stressed monodisperse rubber and glass particle mixtures with 10%, 20%, 40%, and 60% volume rubber content: sample 1
No full textThis dataset contains 8 micro X-ray Computed Tomography (micro-XRCT) data sets from scans of cylindrical particulate mixture samples (diameter 80 mm; unloaded height 80 mm) under different uniaxial compression loads. The samples consist of monodisperse stiff (glass) and soft (rubber) particle mixtures. Both particles have an identical diameter of 4 mm. The considered samples have a volume fraction of 10%, 20%, 40%, and 60% rubber particles. The scans were performed in a low X-ray absorbing transparent oedometer cell with an integrated pair of P-wave ultrasonic transducers to determine in situ the sample stiffness based on wave propagation velocity measurements. On both sides, the wave travels through a 10 mm long Poly (methyl methacrylate) (PMMA) pre-run and after-run section before and after the wave enters and leaves the sample.
The respectively prepared sample inside the oedometer cell was uniaxially compressed in axial direction in subsequent force increments from F_stat. = 200 N to F_stat. = 1000 N (force-controlled) using a Universal Testing Machine (UTM) integrated into the XRCT system. At each force level, the system was relaxed for some time at the defined force to compensate the creep behavior of the soft particles. Subsequently, ultrasonic wave propagation measurements were performed at five different load levels, F_stat. = {200, 400, 600, 800, 1000} N. micro-XRCT scans were acquired in situ at F_stat. = {400, 800} N. For this, it was switched from force-controlled to displacement-controlled to avoid creeping and an eventual movement of the particles during the imaging.
In this data set, the reconstructed 3d volumes ("mixture_nu*_F400N_reconstructed.tar.gz" and "mixture_nu*_F800N_reconstructed.tar.gz"), as well as the projection images ("mixture_nu*_F400N_projections.tar.gz" and "mixture_nu*_F800N_projections.tar.gz") with * indicating the rubber volume fraction nu = {0.1, 0.2, 0.4, 0.6} for both preloads are given. The raw ultrasonic measurement data (transducer signals over time) is provided for all five preloads ("mixture_nu*_ultrasonic_data.tar.gz") as an averaged signal of a stack of 32 signals. The file "mixture_nu*_utm_data.csv" contains the measured axial force and displacement from the UTM during the whole experiment. Based on the measured displacement of the UTM, the current mixture length was determined
Post-Columbian environmental history of Lago Petén Itzá, Guatemala. Revista Mexicana de Ciencias Geológicas
No full textABSTRACT Two ~40-cm-long sediment cores, Revista Mexicana de Ciencias Geológicas, v. 27, núm. 3, 2010, p. 490-507 Pérez, L., Bugja, R., Massaferro, J., Steeb, P., van Geldern, R., Frenzel,. P, Brenner, M., Scharf, B., Schwalb, A., 2010, Post-Columbian environmental history of Lago Petén Itzá, Guatemala: Revista Mexicana de Ciencias Geológicas, v. 27, núm. 3, p. 490-507. Post-Columbian environmental history of Lago Petén Itzá, Guatemala 491 RESUMEN Dos núcleos de sedimentos PI-SC-1-10m y PI-SC-2-40m de 40 cm de largo fueron extraídos bajo un tirante de agua de 10 y 40 m en el Lago Petén Itzá, Departamento de Petén, en el norte de Guatemala. Los núcleos abarcan los pasados ~525 años de acumulación de sedimentos en el lago. Este estudio explora los cambios en los niveles del lago y cambios en el estado trófico que el Lag
Effects of surface roughness on the kinetic interface-sensitive tracer transport during drainage processes
No full textPorous media surface roughness strongly influences the transport of solutes during drainage due to the formation of thick water films (capillary condensation) on the surface of the porous medium. For interfacially-reacted, water-based solutes, these water films increase both the solute production at the fluid-fluid interface, due to the increased number of fluid-fluid interfaces, and the loss of the solute due to retention in the water films. This study applied a pore-scale, direct numerical simulation with the phase-field method-based continuous solute transport model to simulate the reactive transport of the kinetic interfacial sensitive tracer. The study is implemented during primary drainage in a 2D slit with rough solid walls, where the fractal geometries of the solid surfaces were generated numerically. The moving interfacial area is found to be changing non monotonically with the root mean square of surface roughness. With increasing root mean square roughness, the average film thickness increases linearly, whereas the film-associated interfacial area per smooth surface area converges to a value slightly larger than one. The retention of the solute mass produced by the moving meniscus in the water film is observed, and this is described by a film-associated mobile mass retention term. An implicit relation between the mobile interfacial area and the solute mass in flowing zones is found. Finally, it is found that the film-associated mobile mass retention term is linearly related to the root mean square roughness.</p
Primary drainage experiments and fractal dimensions
No full textThe current repository contains raw data in the shape of images collected during a systematic laboratory study, examining the usability of the fractal dimension in the characterization of the flow regime. The study is presented in the paper by Karadimitriou et al., 2024. The two fluids were the wetting phase (WP), FluorinertTM, FC-43, and the non-wetting phase (NWP), deionized water mixed with ink, and occasionally with a specific amount of Glycerol. The wetting phase was initially introduced into the pore space of a Poly-Di-Methyl-Siloxane (PDMS) micromodel, fully saturating it. Then, primary drainage scenarios were realized with the introduction of the non-wetting phase under controlled-flux conditions.
The objective of the study was to investigate the usability of the fractal dimension of various geometrical entities, like the interfaces between phases, and the bulk non-wetting phase occupancy of the pore space, in the characterization of the flow regime.
Main data
The dataset is populated with the raw images acquired during a primary drainage process. Every drainage process took place under a fixed boundary volumetric flux, which is depicted in the title of each file, in terms of the corresponding capillary number. Additionally, the title of each file also includes the viscosity ratio between the invading and the defending phase. A typical file name is in the form Ca=***,M=***.tar. In the images, the non-wetting phase, namely water, shows as dark, and the wetting phase, namely Fluorinert, shows as transparent within the boundaries of the pore network. Flow takes place from right to left.
Procedure followed for each constant Ca and M experiment
The term “experiment” pertains to the breakthrough of the non-wetting phase from its own inlet to the outlet, at a constant boundary flux. For every experiment, a fixed capillary number value, Cai, i = 1,2,3, is maintained, whereas the viscosity ratio between the invading and the defending phase remains the same through a single experiment. In order for the viscosity ratio to be fixed on demand, Glycerol was added to water at specific concentrations, so as to achieve the desired viscosity of water. The Ca used were 10-2, 10-3, 10-4, and 10-5. The viscosity ratios used were 0.2, 1, and 10.
The flow network has overall dimensions of 15 by 20 millimeters, with a mean pore size of 410 microns, and a depth of 100 microns. It is an exact replication of the network used in the work of Sivanesapillai et al., 2018.
The micromodel is initially saturated with the wetting phase. Then, the non-wetting phase is injected into the microfluidic pore network. The non-wetting phase is injected at a fixed volumetric flux to maintain a constant value of the capillary number, Ca, during the entire experiment. The wetting phase is getting passively displaced during this process. Even though the experiment, for the needs of the corresponding publication, concludes at breakthrough, some more images are acquired for future purposes.</p
Influence of the thickness of amorphous Fe Ni B ribbons on their mechanical properties under neutron-irradiation and thermal annealing
No full textSIGLESpecial print from: Steeb, S.; Warlimont, H. (eds.): Rapidly quenched metals, Elsevier, Amsterdam (Netherlands), 1985, p. 1377-1380 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
In vitro-Abzugsversuche an Mesostrukturen mittels Folienprägetechnik auf Zirkonoxidkeramik(ZrO2) und Sekundärkoni aus Kobalt-Chrom-Molybdän(Co-Cr-Mo)
No full textDoppelkronensysteme mit definierter und reproduzierbarer Haftkraft, mit einem dem natürlichen Prämolaren ähnlichen Aussehen und Wegfall der bisher bestehenden Korrosionsproblematik stehen im Mittelpunkt dieser Arbeit. Hierfür wurden 9 Zirkonoxidprimärkronen aus Cercon® (Fa. DeguDent, Hanau) zusammen mit NEM-Sekundärkronen aus Vi-Comp® (Fa. Austenal, Köln) hergestellt. Mit Hilfe einer Folienprägetechnik wurde für alle Prüfkörper jeweils eine Mesostruktur aus einer 50µm Gold-Platin-Folie gefaltet, welche dann mittels Composit Attachment Cement (Nimetic Cem®, Seelfeld) auf V2A-Stahlstäbe befestigt wurden. Diese Prüfkörper wurden mit je 50, 100, 200N belastet und unter Luft, Wasser und Clandosane® (cell pharm, Hannover) mit je 125, 150 und 500mm/min durch die Universalprüfmaschine Zwick Z 050 abgezogen. Anschließend wurde die für die Trennung notwendige Abzugskraft Fz gemessen. Pro Probenkörper wird ein Vorlauf von 100 Zyklen mit 50N Belastung durchgeführt. Die Messung wurde für alle 9 Prüfkörper je 3 mal wiederholt. Der Prüfkörper Nr. 4 wurde aufgrund seiner zu hohen Medianwerte von vergleichsweise >50% der Abzugskraft als Ausreißer von der Analyse ausgeschlossen, so dass 648 Messwerte resultierten. Mit Hilfe des Hystereseprogrammes testXpert® der Universalprüfmaschine Z 050 (Fa. Zwick, Ulm) konnte die Abzugskraft Fz entsprechend des Kurvenpeaks unterhalb der Nulllinie bestimmt werden. Die vorab erwarteten Ergebnisse haben sich alle bestätigt: Milieu (Viskosität), Aufpresskraft Fp und Abzugsgeschwindigkeit v haben in genannter Reihenfolge in absteigender Wertigkeit Einfluss auf die Haftkraft Fz. Die Abzugskraft FZ steigt bei gleich bleibender Abzugsgeschwindigkeit v mit zunehmender Aufpresskraft Fp bei gleichem Milieu bei Zimmertemperatur (ca. 20°C). Ebenso steigt sie mit zunehmender Milieuviskosität, bei gleicher Aufpresskraft Fp, bei gleich bleibender Abzugsgeschwindigkeit v und bei Zimmertemperatur (ca. 20°C). Die Abzugskraft FZ sinkt mit steigender Abzugsgeschwindigkeit v bei gleich bleibender Aufpresskraft Fp, sowohl bei gleichem Milieu, als auch bei Zimmertemperatur (ca. 20°C). 1 In vitro-Abzugsversuche an Mesostrukturen mittels Folienprägetechnik auf Primärkoni aus Zirkonoxidkeramik (ZrO2) und Sekundärkoni aus Kobalt-Chrom-Molybdän (Co-Cr-Mo) Autor: Annette Siebert-Steeb Vergleichbare Abzugswerte sind bei der konventionellen Folienkonusversion NEM-NEM 5° und der hier verwendeten ZrO2-NEM 6° Version zu finden. Der Zahntechniker kann über Variieren des Entlastungsspaltes mit Hilfe der Dicke des Platzhalterlackes auf die Haftungseigenschaften der Folienkonuskronen Einfluss nehmen, d.h. je kleiner der Spalt, desto schneller ist das Kraftmaximum erreicht. Wodurch extraoral die Haftkraft definiert werden, ohne nach intraoraler Verklebung böse Überraschungen zu erleben. Ursächlich für die Haftkraft ist das Tribologische System (der hydraulische und adhäsive Effekt), vergleichbar mit den Galvanodoppelkronen. Es zeigt sich ein signifikanter Einfluss der Aufpresskraft Fp auf die Abzugskraft FZ. Die Haftkraft des Konus durch den Winkel wirkt primär, dann sinkt bei steigender Abzugsgeschwindigkeit die Haftkraft entgegen den Galvanoteleskopen. Somit besteht ein umgekehrter linearer Zusammenhang zwischen Abzugskraft FZ und Abzugsgeschwindigkeit v.This investigation focused on double-crown systems with defined and replicable adhesive strength, a natural appearance similar to premolars and absence of the former problem of corrosion. Nine zirconium oxide primary crowns were manufactured using Cercon® (produced by DeguDent, Hanau) along with NEM secondary crowns made from Vi-Comp® (produced by Austenal, Cologne). A mesostructure was made by folding 50µm gold platinum foil for all the test specimens following the embossing foil technique. These structures were cemented onto V2A steel posts using a composite attachment cement (Nimetic Cem®, Seelfeld). The test specimens were subjected to 50, 100, 200N and retention tested for the treatment groups air, water and Clandosane® (cell pharm, Hannover) at 125, 150 and 500mm/min on the Universal Zwick Z 050 testing machine. Thereafter the pull-off Fz force required for separation was measured. Each test specimen was subjected to 100 cycles of 50N. The measurement was repeated 3 times for all nine test specimens. Test specimen no. 4 was excluded from the analysis as a maverick due to its high median values of >50% of the pull-off force, which resulted in a remaining 648 measurements. The pull-off force Fz was determined in accordance with the curve peak under the zero line by applying the hysteresis software testXpert® of the Universal Z 050 testing machine (Zwick, Ulm). All the predicted results were confirmed: Milieu (viscosity), compression load Fp and pull-off speed v affect the retention strength Fz in decreasing order of priority. The pull-off force Fz increases for a constant pull-off speed v with an increasing compression load Fp for the same milieu viscosity at room temperature (approx. 20°C). Likewise it increases with increasing milieu viscosity for a constant compression load Fp, constant pull-off speed v at room temperature (approx. 20°C). The pull-off force Fz decreases with increasing pull-off force v for constant compression load Fp, for a constant milieu and room temperature (approx. 20°C). 1 In vitro investigation of the retention strength of secondary structures based on embossing a foil on the primary abutment crowns made from zirconium oxide ceramic (ZrO2) and secondary structure from cobalt chrome molybdenum (Co-Cr-Mo) Author: Annette Siebert-Steeb The retention values of the conventional foil structure version NEM-NEM 5° are comparable to those of the ZrO2-NEM 6° version used in this investigation. The dental technician can influence the adhesion properties of the foil structure crown control by varying in the ease gap according to the thickness of the die spacer. The smaller the gap, the faster maximum strength is achieved. The adhesive strength is defined extra-orally without there being unpleasant surprises following intraoral adhesion. The source of the retention strength is the tribological system (hydraulic and adhesive effect) and is comparable to that of galvano double crowns. It is clear that compression load Fp has a significant effect on pull-off force FZ. The adhesive strength of the structure is primarily due to its angle, as the pull-off speed increases the retention strength of the galvano telescopes decreases. Thus there is an inverse linear correlation between the pull-off force FZ and pull-off speed v
A quantitative analysis of Salmonella Typhimurium metabolism during infection
No full textIn this thesis, Salmonella metabolism during infection was investigated. The goal was to gain a quantitative and comprehensive understanding of Salmonella in vivo nutrient supply, utilization and growth.
To achieve this goal, we used a combined experimental / in silico approach. First, we generated a reconstruction of Salmonella metabolism ([1], see 2.1). This reconstruction was then combined with in vivo data from experimental mutant phenotypes to build a comprehensive quantitative in vivo model of Salmonella metabolism during infection (unpublished data, see 2.2). The data indicated that Salmonella resided in a quantitatively nutrient poor environment, which limited Salmonella in vivo growth. On the other hand, the in vivo niche of Salmonella was qualitatively rich with at least 45 different metabolites available to Salmonella. We then used the in vivo model of infection to analyze reasons for the preponderance of Salmonella genes with undetectable virulence phenotype (unpublished data, see 2.3). Our data indicated that host supply with diverse nutrients resulted in large-scale inactivity of numerous Salmonella metabolic pathways. This together with extensive metabolic redundancy was the main cause of the massive Salmonella gene dispensability during infection. To verify this hypothesis experimentally, an unbiased method for large scale mutagenesis was developed (unpublished data, see 2.4). Results from 20 Salmonella mutator lines indicate that Salmonella can tolerate at least some 2700 to 3900 mutations, emphasizing again that a vast majority of Salmonella genes are dispensable in a defined environment
RECENT STRUCTURAL RESULTS WITH AMORPHOUS ALLOYS USING NEUTRON DIFFRACTION
No full textLes facteurs de structure partielle, les distances atomiques, les nombres de coordination partielle et les paramètres d'ordre à courte distance ont été déterminés pour les alliages amorphes Dy80 Ni20 et Ni80 P20. Les corrélations D - D ont été également déterminées dans un alliage amorphe Dyo69 Nio31 deutéré à 10 % at. Enfin, des mesures de diffusion aux petits angles utilisant le contraste variable de Ni dans am - Ni80 P20 ont mis en évidence l'existence de deux phase de compositions différentes.Partial structure factors and partial pair correlation functions as well as atomic distances, partial coordination numbers and short range order parameters are presented for the amorphous alloys Dy80Ni20 and Ni80P20. Comparing to partial functions obtained earlier with Ni81Bl9 and Y67Ni33 we report on striking similarities between the partial pair correlation functions between those pairs which belong to one and the same of the following groups : Group 1 : Ni -P (from Ni80P20) ; Ni-B(Ni81B19) ; Ni-Dy(Dy69Ni31) ; Ni-Y(Y67Ni33) Group 2 : P-P(Ni80P20) ; B-B(Ni81B19) ; Ni-Ni(Dy69Ni31) ; Ni-Ni (Y67Ni33) Group 3 : Ni-Ni (Ni80P20) ; Ni-Ni (Ni81B19) ; Dy-Dy (Dy69Ni31 ; Y-Y(Y67Ni33). With a-Dy69Ni31 containing 10a/o D we show that it will be possible to determine D-D correlations by neutron diffraction with an alloy made from zero-scattering Dy and from zero-scattering Ni. With a-Ni80P20 we report for the first time on the evaluation of partial structure factors in the small Q-Region which show that a-Ni80P20 consists of two phases namely a matrix a certain cNi/cp-ratio and regions with diameters of 15Å and a different cNi/cp-ratio
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