Dissertations / Theses on the topic 'Interphase'
To see the other types of publications on this topic, follow the link: Interphase.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Interphase.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Zhang, Jie. "Multifunctional composite interphase." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-88763.
Full textAbstract:
In this work, carbon nanotubes were deposited onto the insulative glass fibre surface to form a semiconductive network. Utilizing the unique properties of CNTs network, a multifunctional composite interphase could be achieved. The interfacial adhesion strength was improved by CNTs distributed in the interphase. The semiconductive interphase have been used as a chemical/phaysical sensor, strain sensor and microswitch.
2
Abdennur, Nezar(Nezar Alexander). "Unfolding genome organization in interphase." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122537.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Computational and Systems Biology Program, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 147-166).
Genomic contact frequency maps obtained from high throughput chromosome conformation capture technologies have revealed several organizing patterns of mammalian interphase chromosomes, including self-interacting topologically associating domains (TADs) which are believed to function as coherent gene regulatory neighborhoods. However, the mechanisms driving these patterns are still unknown. In this thesis, I describe and apply computational methods that test the predictions of a recently proposed loop extrusion model in the context of experimental perturbations of its key molecular players. In the first project I introduce a new data model, file format, and supporting software package to cope with the challenges of the increasing size and resolution of Hi-C datasets, including a parallel and scalable matrix balancing implementation.
In the second project, I show that depletion of the Structural Maintenance of Chromosomes (SMC) complex, cohesin, in non-cycling mouse liver cells completely eliminates the appearance of TADs in Hi-C maps while preserving genome compartmentalization. In the third project, I demonstrate that depletion of a closely related SMC complex, condensin II, which plays a major role in mitotic chromosome condensation but is also found in the nucleus in interphase, has no impact on gene expression or the maintenance of genome organization in non-dividing cells. In the final project, I compile further evidence for loop extrusion in interphase by employing a combination of polymer simulations and meta-analysis of several Hi-C studies that performed targeted perturbations to modulate the presence of cohesin and the insulator protein, CTCF, on chromatin.
Together, these projects show that rather than being folded in a hierarchical fashion, mammalian genomes in interphase are organized by at least two distinct and antagonistic processes: global compartmental segregation dependent on epigenetic state, and local compaction dependent on cohesin. The latter process is likely to be the dynamic extrusion of chromatin loops driven by a yet-to-be-characterized motor activity of cohesin complexes and limited by DNA-bound CTCF extrusion barriers.
by Nezar Abdennur.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Computational and Systems Biology Program
3
Didier, Yves. "In-situ interphase formation in polymer composites." Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434548.
Full text
4
Pomes-Hadda, Mickael. "Caractérisations et performances des assemblages collés époxyde-amine/aluminium." Thesis, Toulouse, INPT, 2015. http://www.theses.fr/2015INPT0067/document.
Full textAbstract:
La caractérisation et l’évaluation des propriétés physiques, chimiques, physico-chimiques et mécaniques sont un point important dans la compréhension du comportement des assemblages collés polymère/substrat. La spectroscopie diélectrique est une méthode de caractérisation efficace permettant d’étudier la dynamique moléculaire, et permettre aussi un suivi in situ de joints collés. La modélisation mathématique de résultats expérimentaux par la méthode de l’analyse par intervalle permet de s’affranchir de nombreux défauts de logiciels utilisés couramment (erreur expérimentale prise en compte dans les calculs du modèle, permet d’accepter ou de rejeter un modèle, …). Il a été démontré qu’en présence d’un substrat métallique, une compétition avait lieu entre la réaction de polymérisation et des réactions entre les monomères et les substrats métalliques, menant à une interphase (i.e. interface d’épaisseur non nulle) ayant des propriétés différentes des propriétés du même polymère en volume. Ces propriétés influent sur l’adhérence entre le polymère époxydeamine et le substrat d’aluminium. L’adhérence sera caractérisée par un test normé et reliée aux propriétés de l’interphase par diverses techniques. Des vieillissements de systèmes DGEBAanime/ aluminium ont été effectués. Durant ces vieillissements, des tests destructifs et non destructifs ont été effectués afin d’avoir un suivi sur les propriétés des interphases et interfaces de ces joints collés. Les résultats obtenus ont été mis en corrélation afin de pouvoir être capable par l’utilisation de tests non destructifs in situ, de pouvoir prévenir une rupture à l’interphase/interface entre l’adhésif et le substratCharacterization and evaluation of physical, chemical, physico-chemical and mechanical properties are an important point in the comprehension of the behavior of bonded polymer/substrate assemblies. Dielectric spectroscopy is an effective method of characterization to study molecular dynamics, and also allow in situ monitoring of bonded joints. Mathematical modeling of experimental results by the method of interval analysis overcomes many shortcomings of commonly used software (experimental error taken into account, accept or reject a model ...). It has been shown that in the presence of a metal substrate, a competition was held between the polymerization reaction and the reactions between the monomers and metal substrates, leading to an interphase (i.e. non-zero thickness of interface) having properties different than these of the bulk. These properties influence the adhesion between the epoxy-amine polymer and the aluminum substrate. Adhesion will be characterized by a standardized test and related to the properties of the interphase by various techniques. The aging of DGEBA-anime/aluminum system have been done during this study. During the aging, destructive and non-destructive tests were carried out in order to have a follow-up on the properties of interfaces and interphases of these bonded joints. The results were correlated in order to be able to use an in situ non-destructive testing to prevent the rupture at the interphase/interface between the adhesive and the substrate
5
Chung, Jaeun. "Nanoscale characterization of epoxy interphase on copper microstructures." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979725127.
Full text
6
Oostenbrugge, Robert Jan van. "Interphase cytogenetics in the cytodiagnosis of leptomeningeal metastases." [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 1999. http://arno.unimaas.nl/show.cgi?fid=6838.
Full text
7
Filippo, Miriam Di. "Analysis of the chromatin structure in interphase nuclei." Thesis, Open University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489905.
Full textAbstract:
This thesis is devoted to the characterization and detailed understanding of the base compositional patterns and the distribution of genes in the chromosomes of the chicken genome. Vertebrate chromosomes are organized into isochores, very long DNA segments (»300 kb) that are compositionally fairly homogenous, and characterized by different GC levels.
8
Kinloch, Stephen Adam. "Interphase modification in TATB filled polymer bonded explosives." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303329.
Full text
9
Cimaszewski, Steven A. (Steven Andrew). "Statistical analysis of fiber composite interphase inverse problem." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35411.
Full text
10
Ashirgade, Akshay A. "Mechanistic study of the rubber-brass adhesion interphase." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1291145141.
Full text
11
Safavi-Ardebili, Vahid. "Micromechanical characterization of the interphase zone in adhesive joints." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0009/NQ35308.pdf.
Full text
12
Wu, Shanqiang. "Development of zeolite containing catalytic membranes as interphase contactors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0025/NQ36339.pdf.
Full text
13
Stinson, Michael J. "Interphase transfer processes in cocurrent two phase channel flow." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17215.
Full text
14
Luo, Danhui. "Interphase transfer processes in cocurrent two phase channel flow." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/17222.
Full text
15
Choudhry, Mohammad Arshad. "Crystallography of phase transformations and interphase boundaries in materials." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/847304/.
Full textAbstract:
The main purposes of this study were; (i) to apply the theory of martensite crystallography to martensitic transformations in low-symmetry materials, (ii) to investigate, using the computer simulation method, the microscopic structure of complex interphase boundaries which are not yet fully understood in terms of the martensitic mechanism. Although the unique symmetry of a twin boundary makes it a rather exceptional kind of interface, it is clearly a particularly appropriate starting point especially due to the role which twinning plays in martensitic transformations. The accuracy of twinning modes is vital for their use as lattice-invariant shears in theories of martensite crystallography. Potential twinning modes for zirconia were determined using the analysis due to Bilby and Crocker (1965) and the associated atomic shuffling was also considered. Twinning orientation relationships involving a screw axis and a glide plane have been established. The theory of martensite crystallography (Acton et al. 1970) was then applied to the tetragonal to monoclinic martensitic transformation in zirconia. The predictions for the habit plane, shape strain and the direction of the shape deformation were obtained and compared with available experimental observations. The application of the theory was also extended to the face-centred cubic to monocline martensitic transformation in plutonium alloys. The predictions of the crystallographic features for this transformation are reported. The computer simulation method was applied to investigate the relaxed atomic structure and energies of the complex interphase boundaries. The (100)b//(100)f and the (011)b /(111)f interphase boundaries were investigated using interatomic potential. Special consideration was given to the misfit dislocations at the interface which can accomplish the lattice-invariant shear of the phenomenological theories of martensite crystallography. A new equilibrium interatomic potential for iron was developed to study the relaxed structure of the (225)f b. c. c. /f. c. c. interphase boundary. These results are also compared with experimental information. Finally the general results of the thesis are discussed and main conclusions summarized.
16
Laborie, Marie-Pierre Genevieve. "Investigation of the Wood/Phenol-Formaldehyde Adhesive Interphase Morphology." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26411.
Full textAbstract:
This work addresses the morphology of the wood/ Phenol-Formaldehyde (PF) adhesive interphase using yellow-poplar. In this case, morphology refers to the scale or dimension of adhesive penetration into wood. The objective is to develop methods for revealing ever smaller levels of wood/resin morphology. Dynamic techniques that are commonly utilized in polymer blend studies are investigated as potential methods for probing the wood/ adhesive interphase morphology. These are Dynamic Mechanical Analysis (DMA) and solid state NMR using CP/MAS. PF resin molecular weight is manipulated to promote or inhibit resin penetration in wood, using a very low or a very high molecular weight PF resin.
With DMA, the influence of PF resin on wood softening is investigated. It is first demonstrated that the cooperativity analysis according to the Ngai coupling model of relaxation successfully applies to the in-situ lignin glass transition of yellow-poplar and spruce woods. No significant difference in intermolecular coupling is detected between the two woods.
It is then demonstrated that combining simple DMA measurements with the cooperativity analysis yields ample sensitivity to the interphase morphology. From simple DMA temperature scans, a low molecular weight PF (PF-Low) does not influence lignin glass transition temperature. However, the Ngai coupling model of relaxation indicates that intermolecular coupling is enhanced with the low molecular weight PF. This behavior is ascribed to the low molecular weight PF penetrating lignin on a nanometer scale and polymerizing in-situ.
On the other hand, a high molecular weight resin with a broad distribution of olecular weights (PF-High) lowers lignin glass transition temperature dramatically. This plasticizing effect is ascribed to a small fraction of the PF resin being low enough in molecular weight to penetrate lignin on a nanoscale, but being too dispersed for forming a crosslinked network.
With CP/MAS NMR, intermolecular cross-polarization experiments are found unsuitable to probe the angstrom scale morphology of the wood adhesive interphase. However, observing the influence of the PF resins on the spin lattice relaxation time in the rotating frame, HT1r, and the cross-polarization time (TCH) is useful for probing the interphase morphology. None of the resins significantly affects the cross-polarization time, suggesting that angstrom scale penetration does not occur with a low nor a high molecular weight PF resin. However, the low molecular weight PF substantially modifies wood polymer HT1r, indicating that the nanometer scale environment of wood polymers is altered. On the other hand, the high molecular weight PF resin has no effect on wood HT1r. On average, the high molecular weight PF does not penetrate wood on a nanometer scale. Interestingly, the low molecular weight PF resin disrupts the spin coupling that is typical among wood components. Spin coupling between wood components is insensitive to the high molecular weight PF. Finally, it is noteworthy that the two PF resins have significantly different T1r 's in-situ. The low molecular weight resin T1r lies within the range of wood relaxations, suggesting some degree of spin coupling. On the other hand, the T1r of the high molecular weight PF appears outside the range of wood relaxations. Spin coupling between the high molecular weight resin and wood components is therefore inefficient.
The CP/MAS NMR and DMA studies converge to identify nanometer scale penetration of the low molecular weight PF in wood. On the other hand, the high molecular weight PF resin forms separate domains from wood, although a very small fraction of the PF-High is able to penetrate wood polymers on a nanoscale.Ph. D.
17
Giunta, Rachel K. "Durability of Polyimide/Titanium Adhesive Bonds: An Interphase Investigation." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29449.
Full textAbstract:
When bonded joints are subjected to harsh environmental conditions, the interphase, the three-dimensional region surrounding the adhesive/substrate interface, becomes critically important. Frequently, failure occurs in this region after adhesively bonded systems are subjected to elevated temperature oxidative aging. In a previous study, this was found to be the case with a polyimide adhesive bonded to chromic acid anodized (CAA) Ti-6Al-4V. The objective of the current research has been twofold: 1) to investigate the effect of thermal aging on the interphase region of polyimide/titanium adhesive joints, and 2) to evaluate the method used in the current study for durability characterization of other adhesive/substrate systems.
The method used in this research has been to characterize the effect of elevated temperature aging on the following systems: 1) Notched coating adhesion (NCA) specimens and 2) bulk samples of dispersed substrate particles in an adhesive matrix. The NCA test has the advantages of an accelerated aging geometry and a mode mix that leads to failure through the interphase, the region of interest. The bulk samples have the advantage of an increased interphase volume and allow for the application of bulk analysis techniques to the interphase, a region that is traditionally limited to surface analysis techniques.
The adhesive systems studied consisted of one of two polyimide adhesives, LaRC⠢ PETI-5 or Cytec Fiberite⠢ FM-5, bonded to CAA Ti-6Al-4V. The model filled system consisted of a PETI-5 matrix with amorphous titanium dioxide filler. Through the use of the NCA test, it was determined that bonded specimens made with FM-5 lose approximately 50% of their original fracture energy when aged in air at 177°C for 30 days. This aging temperature is well below the glass transition temperature of the adhesive, 250°C. At the same time, the failure location moves from the anodized oxide layer to the adhesive that is directly adjacent to the substrate surface, the interphase region. Through surface analysis of this region, it is determined that the adhesive penetrates the pores of the CAA surface to a depth of 70 to 100 nm, promoting adhesion at the interface. With aging, the adhesive in the interphase region appears to be weakening, although analysis of the bulk adhesive after aging shows little change. This indicates that adhesive degradation is enhanced in the interphase compared to the bulk.
Analysis of the model filled system gave similar information. Specimens containing titanium dioxide filler had glass transition temperatures that were approximately 20°C lower than the neat polyimide samples. In addition, the filled samples contained a significant portion of low molecular weight extractable material that was not present in the neat specimens.
The tan delta spectra from dynamic mechanical thermal analysis of the filled specimens exhibited a shoulder on the high-temperature side of the glass transition peak. This shoulder is attributed to the glass transition of the interphase, a distinct phase of the polyimide which is constrained by adsorption onto the filler particle surfaces. As a function of aging time at 177° or 204°C, the shoulder decreases substantially in magnitude, which may relate to loss of adhesive strength between the polyimide and the filler particles.
From this research, it has been illustrated that information relating to the durability of adhesively bonded systems is gained using an interfacially debonding adhesive test and a model system of substrate particles dispersed in an adhesive matrixPh. D.
18
Holmfeldt, Per. "Regulation of tubulin heterodimer partitioning during interphase and mitosis." Doctoral thesis, Umeå : Department of Molecular Biology, Umeå University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1923.
Full text
19
Liao, Nam. "Characterization and interphase mechanical properties of epoxy/PVP blends." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-11072008-063038/.
Full text
20
Mahmood, Haroon. "Multifunctionality in epoxy/glass fibers composites with graphene interphase." Doctoral thesis, Università degli studi di Trento, 2017. https://hdl.handle.net/11572/368851.
Full textAbstract:
In this project, the synergetic effect of a graphene interphase in epoxy/glass fibers composites was investigated by coating glass fibers (GF) with graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets by an electrophoretic deposition (EPD) technique. Graphite oxide was prepared using modified Hummers method in which raw graphite powder was oxidized using potassium permanganate (KMnO4) in acidic solution. Using ultrasonic technique, the graphite oxide was dispersed homogenously in water to create a stable GO suspension which was used as a bath in the EPD process. For the coating process, two copper plates were used as electrodes in the EPD process in which GF were placed in front of anode for GO deposition since GO tends to carry negative charges due to oxygen functional groups attached on the graphene structure as produced in the modified Hummers method. The deposition was carried out at different applied fields while maintaining the dispersion concentration and deposition time constant. This process produced GF coated with GO nanosheets, while to obtain GF coated with rGO, GO coated fibers were subjected to chemical reduction process where the fibers were placed in an environment of hydrazine hydrate which reduced the GO coating on GF. Through this step, rGO coated GF were obtained. The oxidation level of GO and rGO was evaluated using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron (XPS) spectroscopy techniques which confirmed the successful oxidation of graphite powder into graphite oxide due to liquid chemical oxidation process while the hydrazine reduction method reduced the oxygen amount from 34% to 10% in GO hence converting it into rGO. Scanning electron microscopy analysis of coated fibers revealed uniform coating of GF with GO and rGO where the amount of deposition increased with increased applied field.
The effect of GO or rGO coating on GF obtained by EPD process was first evaluated by determining the adhesion between GF and epoxy matrix. Single fiber fragmentation test was utilized to determine the interfacial shear strength (ISS) between the uncoated or coated fibers and epoxy matrix. Single fiber epoxy composites were prepared by using GO and rGO coated fibers and were tested using a mini-tensile testing machine and monitoring the lengths of fragments of fibers obtained during the tensile test. It was observed that in case of GO coated fibers, the ISS increased by 218% in comparison to uncoated fiber based composite. The increase of interfacial adhesion in this case, it can be attributed to the fact that GO carries oxygen functional groups which creates physical and chemical bonding between both the GF surface and the epoxy matrix. For investigating the interactions between GF and GO, atomic force microscopy (AFM) was used to determine the interfacial adhesion between them by scratching GO on GF. It was proved that the delamination strength was higher than the ISS, hence proving the efficacy of the selected GO deposition method. On the other hand, single fiber fragmentation tests indicated a 70% increase in ISS for rGO coated GF when embedded in the epoxy matrix as compared to uncoated fibers. This increment is lower than that observed for GO coated fibers and it has been attributed to the fact that rGO does not possess enough oxygen based functional groups to efficiently interact with the polymer matrix. The observed increase in ISS with respect to uncoated GF is based on the frictional forces offered by the roughness of rGO nanosheets. This confirms that the presence of an interphase (either GO or rGO) creates favorable load transfer mechanism through either chemical or physical bonding or even both depending on the nature of the interphase. To test further the positive effect of GO based interphase in epoxy/glass composites in terms of mechanical reinforcement, multifiber (uncoated and GO or rGO coated) reinforced epoxy composites were created by hand lay-up method. Laminas of fibers were wetted by epoxy resin and stacked over one another in certain number depending on the thickness of the resultant composite. These composites were subjected to various mechanical tests, such as flexural tests, short-beam shear tests, mode I interlaminar fracture toughness and creep tests which also confirmed that GO and rGO based interphase in epoxy/glass composites increase the performances of the composite with respect to that of the uncoated GF based composites. GO proved to be the best interphase in terms of mechanical properties obtained, as proved before. The multifunctionality of such interphases based on graphene was analyzed and confirmed using multiple tests on epoxy/glass composites containing uncoated and coated (GO or rGO). In particular, the electrical and thermal conductivity of the composites were tested in which the composites based on rGO interphase showed the highest conductivity which not only confirms that rGO coated fibers in epoxy/glass composites render the composites conductive but also proves the successful chemical reduction process used in this work.
These conductive composites were subjected to piezoresistivity tests in which the applied longitudinal strain in different modes resulted in change in resistance thus showing a possibility of using such composites as strain sensing devices or for structural health monitoring purposes in automotive or aerospace applications.
These conductive composite specimens were also analyzed for their dielectric properties. The tests showed increased permittivity values as compared to both uncoated and GO coated composites thus revealing the possibility to use composites containing rGO coated fibers for electromagnetic interference shielding applications.
21
Mahmood, Haroon. "Multifunctionality in epoxy/glass fibers composites with graphene interphase." Doctoral thesis, University of Trento, 2017. http://eprints-phd.biblio.unitn.it/2077/1/Thesis_draft_(Final)_-_7_HM.pdf.
Full textAbstract:
In this project, the synergetic effect of a graphene interphase in epoxy/glass fibers composites was investigated by coating glass fibers (GF) with graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets by an electrophoretic deposition (EPD) technique. Graphite oxide was prepared using modified Hummers method in which raw graphite powder was oxidized using potassium permanganate (KMnO4) in acidic solution. Using ultrasonic technique, the graphite oxide was dispersed homogenously in water to create a stable GO suspension which was used as a bath in the EPD process. For the coating process, two copper plates were used as electrodes in the EPD process in which GF were placed in front of anode for GO deposition since GO tends to carry negative charges due to oxygen functional groups attached on the graphene structure as produced in the modified Hummers method. The deposition was carried out at different applied fields while maintaining the dispersion concentration and deposition time constant. This process produced GF coated with GO nanosheets, while to obtain GF coated with rGO, GO coated fibers were subjected to chemical reduction process where the fibers were placed in an environment of hydrazine hydrate which reduced the GO coating on GF. Through this step, rGO coated GF were obtained. The oxidation level of GO and rGO was evaluated using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron (XPS) spectroscopy techniques which confirmed the successful oxidation of graphite powder into graphite oxide due to liquid chemical oxidation process while the hydrazine reduction method reduced the oxygen amount from 34% to 10% in GO hence converting it into rGO. Scanning electron microscopy analysis of coated fibers revealed uniform coating of GF with GO and rGO where the amount of deposition increased with increased applied field.
The effect of GO or rGO coating on GF obtained by EPD process was first evaluated by determining the adhesion between GF and epoxy matrix. Single fiber fragmentation test was utilized to determine the interfacial shear strength (ISS) between the uncoated or coated fibers and epoxy matrix. Single fiber epoxy composites were prepared by using GO and rGO coated fibers and were tested using a mini-tensile testing machine and monitoring the lengths of fragments of fibers obtained during the tensile test. It was observed that in case of GO coated fibers, the ISS increased by 218% in comparison to uncoated fiber based composite. The increase of interfacial adhesion in this case, it can be attributed to the fact that GO carries oxygen functional groups which creates physical and chemical bonding between both the GF surface and the epoxy matrix. For investigating the interactions between GF and GO, atomic force microscopy (AFM) was used to determine the interfacial adhesion between them by scratching GO on GF. It was proved that the delamination strength was higher than the ISS, hence proving the efficacy of the selected GO deposition method. On the other hand, single fiber fragmentation tests indicated a 70% increase in ISS for rGO coated GF when embedded in the epoxy matrix as compared to uncoated fibers. This increment is lower than that observed for GO coated fibers and it has been attributed to the fact that rGO does not possess enough oxygen based functional groups to efficiently interact with the polymer matrix. The observed increase in ISS with respect to uncoated GF is based on the frictional forces offered by the roughness of rGO nanosheets. This confirms that the presence of an interphase (either GO or rGO) creates favorable load transfer mechanism through either chemical or physical bonding or even both depending on the nature of the interphase. To test further the positive effect of GO based interphase in epoxy/glass composites in terms of mechanical reinforcement, multifiber (uncoated and GO or rGO coated) reinforced epoxy composites were created by hand lay-up method. Laminas of fibers were wetted by epoxy resin and stacked over one another in certain number depending on the thickness of the resultant composite. These composites were subjected to various mechanical tests, such as flexural tests, short-beam shear tests, mode I interlaminar fracture toughness and creep tests which also confirmed that GO and rGO based interphase in epoxy/glass composites increase the performances of the composite with respect to that of the uncoated GF based composites. GO proved to be the best interphase in terms of mechanical properties obtained, as proved before. The multifunctionality of such interphases based on graphene was analyzed and confirmed using multiple tests on epoxy/glass composites containing uncoated and coated (GO or rGO). In particular, the electrical and thermal conductivity of the composites were tested in which the composites based on rGO interphase showed the highest conductivity which not only confirms that rGO coated fibers in epoxy/glass composites render the composites conductive but also proves the successful chemical reduction process used in this work.
These conductive composites were subjected to piezoresistivity tests in which the applied longitudinal strain in different modes resulted in change in resistance thus showing a possibility of using such composites as strain sensing devices or for structural health monitoring purposes in automotive or aerospace applications.
These conductive composite specimens were also analyzed for their dielectric properties. The tests showed increased permittivity values as compared to both uncoated and GO coated composites thus revealing the possibility to use composites containing rGO coated fibers for electromagnetic interference shielding applications.
22
Zhang, Wenyong. "Modification of carbon fiber / epoxy matrix interphase in a composite material : Design of a self-healing interphase by introducing thermally reversible Diels-Alder adducts." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0127/document.
Full textAbstract:
Une interphase fibre de carbone/matrice époxy thermiquement auto-réparable a été construite sur la base de liaisons covalentes Diels-Alder (D-A) thermiquement réversibles. L’interphase modifiée par D-A a été formée en greffant des groupes maléimide sur la surface de la fibre de carbone et en introduisant des groupes furane dans le réseau polyépoxy. La capacité d’auto-réparation interfaciale a été caractérisée par le test de déchaussement de la micro-goutte. La surface de la fibre de carbone a subi un traitement en trois étapes : (i) oxydation par l’acide nitrique, (ii) amination par la tétraéthylènepentamine (TEPA) et (iii) greffage de bismaléimide (BMI). Après chaque étape de traitement, les modifications physico-chimiques de surfaces de la fibre ont été caractérisées par microscopies (MEB et AFM) et par spectroscopies (XPS, et ATR-FTIR). La modification de la matrice a été effectuée en copolymérisant le furfuryl glycidyl éther (FGE) au réseau époxy/amine et les propriétés de la matrice ont été évaluées par TGA, DSC, ATR-FTIR, et traction uniaxiale. Le caractère réversible des liaisons Diels-Alder a été également vérifié par DSC, TGA et RMN. Pour caractériser les capacités d'auto-réparation de l’interphase modifiée par D-A, les propriétés mécaniques et les capacités d'auto-réparation de l'interphase construite en combinant la matrice DGEBA-FGE/amine avec une série de fibres de carbone greffés par BMI ont été mesurées en fonction du temps d’oxydation préalable au greffage (gouvernant la réactivité de la fibre de carbone). Enfin, car le FGE joue un double rôle dans le système interfacial modifié par D-A, à la fois dans l’architecture en intervenant comme allongeur de chaîne entre nœuds de réticulation du réseau époxyde et au niveau de l’interphase en contribuant dans la formation des liaisons réversibles, l'influence de la concentration de FGE dans la matrice a été étudiée sur les propriétés mécaniques de l'interphase et également sur les propriétés mécaniques de la matrice. Par conséquent, ce travail a permis d’aboutir à la procédure optimale pour construire une interphase fibre de carbone/époxy thermiquement auto-réparable basée sur des liaisons covalentes Diels-Alder (thermo réversibles). L'interphase ainsi formée possède non seulement des capacités d’auto-réparations multiples, mais également des propriétés mécaniques compatibles avec une approche ‘matériau composite’. En effet, les propriétés mécaniques globales des matériaux composites, comme attendu, sont dépendantes des caractéristiques de cette interphase mais ne seront pas réduites par la présence de celle-ci notamment pour assurer la durabilité du matériau compositeA thermally self-healable carbon/epoxy interphase was designed based on Diels-Alder (D-A) thermally reversible covalent bonds. The D-A modified interphase was formed between maleimide groups grafted on carbon fiber surface and furan groups introduced into epoxy network. The self-healing ability was characterized by a micromechanical approach using the micro-droplet debonding test. In this work, carbon fiber surface underwent a three-step treatment to graft maleimide groups, including HNO3 oxidization, tetraethylenepentamine (TEPA) amination, and bismaleimide (BMI) grafting. The fiber surface physico-chemical modifications after each treatment step were characterized by microscopies (SEM, and AFM) and spectroscopies (XPS, and ATR-FTIR). The matrix modification was carried on mixing furfuryl glycidyl ether (FGE) into epoxy/amine network and the properties of modified matrix were studied by TGA, DSC, ATR-FTIR, and tensile tests. The reversible character of Diels-Alder bond was also followed by DSC, TGA, and NMR. The interfacial mechanical properties and the self-healing abilities of the D-A modified interphases, built by combining DGEBA-FGE/amine matrix with a serial of BMI-grafted carbon fibers tuned as a function of the oxidization time were investigated. At last, since FGE plays a double-role in D-A modified interfacial system, i.e. chain extender in epoxy network and self-healing agent in the interphase, the influences of FGE content in matrix on the mechanical properties of interphase and also on the mechanical properties of cured matrix were evaluated. As a consequence, this study allowed to achieve the best process to build a thermally self-healable carbon/epoxy interphase based on thermally reversible Diels-Alder covalent bonds. The formed interphase has not only the successive self-healable abilities but also the required mechanical properties. Additionally, the overall mechanical properties of the composite material based on this interphase will not be weakened significantly after the interfacial modifications
23
Svensson, Daniel, and Tomas Walander. "Evaluation of an Interphase Element using Explicit Finite Element Analysis." Thesis, University of Skövde, School of Technology and Society, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-3895.
Full textAbstract:
A research group at University of Skövde has developed an interphase element for implementation in the commercial FE-software Abaqus. The element is using the Tvergaard & Hutchinson cohesive law and is implemented in Abaqus Explicit version 6.7 using the VUEL subroutine. This bachelor degree project is referring to evaluate the interphase element and also highlight problems with the element.
The behavior of the interphase element is evaluated in mode I using Double Cantilever Beam (DCB)-specimens and in mode II using End Notch Flexure (ENF)-specimens. The results from the simulations are compared and validated to an analytical solution.
FE-simulations performed with the interphase element show very good agreement with theory when using DCB- or ENF-specimens. The only exception is when an ENF-specimen has distorted elements.
When using explicit finite element software the critical time step is of great importance for the results of the analyses. If a too long time step is used, the simulation will fail to complete or complete with errors. A feasible equation for predicting the critical time step for the interphase element has been developed by the research group and the reliability of this equation is evaluated.
The result from simulations shows an excellent agreement with the equation when the interphase element governs the critical time step. However when the adherends governs the critical time step the equation gives a time step that is too large. A modification of this equation is suggested.
24
Ciprari, Daniel L. "Mechanical Characterization of Polymer Nanocomposites and the Role of Interphase." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4872.
Full textAbstract:
Mechanical characterization of four polymer nanocomposite systems and two pure polymer reference systems was performed. Alumina (Al2O3) and magnetite (Fe3O4) nanoparticles were embedded in poly(methyl methacrylate) (PMMA) and polystyrene (PS) matrices. Mechanical testing techniques utilized include tensile testing, dynamic mechanical analysis (DMA), and nanoindentation. Consistent results from the three techniques proved that these nanocomposite systems exhibit worse mechanical properties than their respective pure polymer systems.
The interphase, an interfacial area between the nanoparticle filler and the polymer matrix, was investigated using two approaches to explain the mechanical testing results. The first approach utilized data from thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM) to predict the structure and density of the interphase for the four nanocomposite systems. The second approach analyzed the bonding between the polymer and the nanoparticle surfaces using Fourier Transform Infrared Spectroscopy (FT-IR) to calculate the density of the interphase for the two PMMA-based nanocomposite systems. Results from the two approaches were compared to previous studies. The results indicate that Al2O3 nanoparticles are more reactive with the polymer matrix than are Fe3O4 nanoparticles, but neither have strong interaction with the polymer matrix. The poor interaction leads to low density interphase which results in the poor mechanical properties.
25
Maierhofer, Christine. "Etablierung der Vielfarben Interphase FISH Dekonvolutions-Mikroskopie zur Einzelzell-Analyse." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-16586.
Full text
26
Park, Paul C. "Spatial localization of transcription and splicing compartments in interphase nuclei." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0013/NQ41483.pdf.
Full text
27
Chen, Meng-Yang. "Précipitations de carbure de vanadium (fibre, interphase) dans des aciers." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENI016/document.
Full textAbstract:
Le travail présenté dans cette thèse est consacré à la précipitation interphase dans les aciers microalliés au vanadium. Il s’agit principalement de mieux comprendre l’évolution des microstructures et des propriétés mécaniques résultantes à partir d’une double approche expérimentale et de modélisation. Les analyses effectuées conjointement en Microscopie Electronique en Transmission et en nanoindentation ont permis de mieux cerner les relations qui existent entre les paramètres microstructuraux de la précipitation interphase (taille moyenne des carbures, distances moyenne entre carbures et entre feuillets, morphologie des carbures) et les modifications de propriétés mécaniques locales induites dans les aciers à très haute résistance. Par ailleurs, nous avons développé un modèle original qui couple les cinétiques de transformation de phases à celle de la précipitation interphase. Ce modèle permet de décrire l’évolution des paramètres microstructuraux et les résultats obtenus sont en très bon accord avec les résultats expérimentauxThe present thesis gives an overview of carbide aggregates (interphase precipitation and carbide fiber) in vanadium-alloyed steels, covering the aspects of microstructure, modeling, and mechanical properties. The microstructural features of different carbide aggregates by the use of microscopies, and the transition of carbide morphologies is discussed. A new model considering the ledge mechanism as well as austenite decomposition is subsequently proposed according to the observed microstructure. The sheet spacing, particle spacing, and interface velocity, can be calculated and show good agreements with experimental data. Finally, the effect of interphase-precipitated carbide distribution (sheet spacing, particle spacing, and carbide radius) on Orowan strengthening contribution is examined by nano-indentation. By the virtue of small indenter, the mechanical properties of single ferrite grain are able to be extracted.Keyword:
28
Wilkinson, Steven P. "Toughened bismaleimides, their carbon fiber composites and interphase evaluation studies." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/38782.
Full textAbstract:
The concept of employing engineering thermoplastics as toughness modifiers for Bismaleimide resins was utilized to improve the fracture toughness properties of these important materials, which have applications as matrix resins for high performance composites. Modifier molecular weight, end group functionality, backbone structure and weight percent incorporation were all studied with respect to their influence on Kj, fracture toughness properties. Increases in fracture toughness were created with thermoplastic oligomers without sacrificing high temperature properties and desirable hot-melt processing conditions. Investigations were also made to study the morphological features that develop within these modified thermosets and their resistance to specific environments. In addition, unidirectional carbon fiber composites were prepared and their mode | and II strain energy release rates measured. Respectable increases in the interlaminar fracture toughness were obtained, 15 and 20 percent by weight loadings of maleimide terminated polysulfone modifiers yielded Gj, values of 489425 and 734+10 Jim2 respectively, a substantial improvement over the control value of 359+17 J/im2.
Laminates were prepared using carbon fibers that had been investigated in terms of their surface energies using Inverse Gas Chromatography. It was illustrated how this technique could distinguish between the acid-base properties of fibers possessing different degrees of proprietary surface treatments. Fiber composites containing both contrasting and subtle changes at the fiber-matrix interphase were prepared and their mechanical properties evaluated using a variety of test methods. Dramatic increases in laminate properties were measured for composites possessing contrasting interphases. Furthermore, the mode II fracture toughness test was sensitive to interphase differences; however, the mode | fracture toughness test was not.
Specimens subjected to the new Continuous Ball Indentation test method (mesoindentation) were compared with single fiber micro-indentation test results. Differences were detected in composites prepared using untreated and surface treated fibers. The new method was also sensitive to changes in matrix ductility. Certain anomalies that were noted to be surprising from micro-indentation measurements were not present in the meso-indentation test results. These observations brought to light certain limitations found within the micro-indentation test, but further supported the new test method as a potential technique for fiber-matrix interphase evaluation.Ph. D.
29
Wang, Jianfeng. "Micromechanics of Granular Media: A Fundamental Study of Interphase Systems." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/27216.
Full textAbstract:
The interphase is a localized region adjacent to a manufactured inclusion that is surrounded by granular soil. These regions are ubiquitous in civil infrastructure and often are components of large-scale composite systems. The interphase region influences load-deformation behavior of the entire composite system. However, mechanisms that control the mechanical behavior of the interphase region and, in turn, control the composite structure behavior, are not clearly understood. Few relationships exist for predicting interphase behavior from properties of granular materials and the inclusion surface that can be measured in the laboratory.
A two dimensional discrete element model of a general interphase system was developed and validated against laboratory data. Numerical experiments are conducted with varying soil to inclusion relative geometry. A new micromechanics-based approach, which utilizes microscopic quantities to explain the mechanics of granular media from a continuum point view, is adopted to investigate the mechanisms that underlie the interphase behavior.
It is shown that the grain to inclusion surface relative geometry controls the degree of granular media strength mobilization by controlling development of fabric and contact force anisotropy inside the interphase region. A unique bilinear relationship exists between the mobilized granular media strength and the principal direction of average contact force anisotropy at the interface between the particles touching the surface and the inclusion. These findings suggest the problem is one of contact and can not be solved using purely geometric correlations, as past research presumed. A fundamental mechanism of behavior, long sought in geomechanics problems, is presented. Publications resulting from this research are significant and original contributions to the geoengineering, material science, geophysics and granular physics literature.Ph. D.
30
Clark, Richard L. "Altering the fiber-matrix interphase in semicrystalline polymer matrix composites." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12042009-020216/.
Full text
31
Gunawardena, Shermali Dione Shiranthini Harina. "Interphase chromosome movement during the midblastula transition in Drosophila melanogaster." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284184.
Full textAbstract:
Eukaryotic chromatin is functionally active only in the interphase nucleus. Indirectly we know that global chromatin changes occur, such that gene expression and replication proceed. I undertook to directly observe the structural changes of interphase chromatin, at a time in Drosophila embryogenesis when many nuclear processes were just beginning to be established. I reasoned that cycle 14 was the ideal time in which to observe chromatin changes as a result of functional processes. During this embryonic stage cellular processes shifts from maternal to zygotic control. Chromosomes also undergo significant changes. To infer the native structure of chromatin, I developed an ultra-sensitive two colour in situ hybridization (FISH) technique and established its limits of resolution. Combining ultrasensitive FISH, with high resolution three-dimensional imaging techniques, I can visualize directly the compaction, position and orientation of genes within the interphase nucleus. I first characterized to a greater extent the chromatin changes in the Notch gene during the mid-blastula transition. I observe that the Notch gene decondense as the embryo ages in cycle 14. I further localized both individually and simultaneously, a variety of genes on the three large chromosomes of Drosophila. I observe that during a single interphase, portions of chromosomes move in a cell cycle specific and directed fashion; both independently and over long distances. From these results I conclude that global chromatin changes occur during interphase. I suggest that chromatin is organized beyond the Rab1 orientation such that the position of the gene on the chromosome allows loci to move independently within the active interphase nucleus. I propose a model for chromatin organization within the Drosophila interphase nucleus. Within the Rab1 order, higher-order chromatin is organized into loop domains, ranging in size from 5--100s of kb. I postulate that loop domains that are centromere proximal are small in size, 5-50 kb, while those centromere distal are larger, often greater than 100 kbs, consistent with the observation that the centromere proximal histone gene cluster is arranged in a 5 kb loop (Mirkovitch et al., 1984), while the Notch gene which is near the telomere, is part of a larger loop (Gunawardena et al., 1999a). The loops are attached to each other by a chromosomal backbone structure. My observations demonstrate that interphase nuclear function is superimposed and permitted on this loop-backbone chromatin organization, such that gene movement occurs (Gunawardena et al., 1999b).
32
Vassaux, Sabine. "Mouillabilité et miscibilité des bitumes : application au recyclage." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS008/document.
Full textAbstract:
Le recyclage des matériaux routiers constitue une voie de développement durable qui présente des bénéfices en termes de consommation d’énergie et de ressources non renouvelables. Pour mieux prédire les propriétés finales de ces matériaux, la compréhension des phénomènes de mélange intervenant lors de la fabrication des enrobés à chaud et à tiède en centrale d’enrobage est indispensable. L’objectif de la thèse est donc de comprendre et d’identifier les facteurs influençant les phénomènes de mouillage, de remobilisation et de miscibilité des liants bitumineux. Pour cela, la démarche d’étude choisie consiste à étudier les interactions locales entre les constituants organiques et inorganiques du mélange selon une approche physico-chimique aux interfaces et interphases. Concernant le mouillage, des indicateurs ont été sélectionnés pour suivre son évolution à l’interface bitume/roche polie. L’influence du vieillissement du liant a aussi été prise en compte. La viscosité et le taux d’asphaltènes des bitumes ainsi que la composition de surface du substrat minéral influencent la qualité de mouillage. Les résultats ont montré que les évolutions étaient régies par un modèle applicable aux surfaces polies, poreuses et chimiquement hétérogènes. La remobilisation du liant vieilli (à température réduite) par le liant d’apport (chauffé à 160°C) a été étudiée à l’interface et à l’interphase sur des échantillons « bitume d’apport/bitume vieilli ». A l’interface, le temps d’étalement est influencé linéairement par la viscosité du liant vieilli. Concernant l’interphase, l’analyse des échantillons bitumineux a montré qu’une diminution de l’écart de températures entre les liants conduit à un meilleur mélange. Des méthodologies ont été développées pour suivre la migration du liant vieilli au moyen de techniques comme la micro fluorescence X, la microscopie infrarouge en mode ATR et en mode d’imagerie ATR. La microscopie infrarouge en mode d’imagerie ATR est particulièrement adaptée pour étudier la remobilisation du bitume vieilli à l’aide de la fonction carbonyle qui résulte de l’oxydation du bitume et traduit son état de vieillissement. Les résultats ont permis de déterminer les paramètres influents tels que la viscosité et la nature du liant vieilli ainsi que l’effet bénéfique d’un produit « régénérant » sur la remobilisation. L’effet d’une énergie d’agitation mécanique améliore également le mélange des liants. Concernant les résultats obtenus par micro fluorescence X, des éléments métalliques entrant dans la composition du bitume ont été choisis comme traceurs internes pour suivre la migration d’un liant. Des hypothèses ont été proposées pour expliquer les différences de migration des traceurs observées. Enfin, l’ensemble des méthodologies développées à l’échelle des liants a été appliqué à l’étude des produits routiers incorporant des granulats neufs et vieillis. Les résultats montrent une cohérence entre les tendances observées à l’échelle microscopique et macroscopique. Le procédé de fabrication à chaud favorise la remobilisation tandis que l’augmentation du taux d’agrégats d’enrobé le freine. L’augmentation du taux d’agrégats réduit également l’homogénéité du mélange bitumineux fabriqué qui a été évaluée au travers de la répartition spatiale de la fonction carbonyle, obtenue par un traitement statistique des cartographies chimiques par microscopie infrarougeIn the road industry, the main challenge is to produce warm-mix asphalt mixtures while incorporating high rates of reclaimed asphalt, which come from the deconstruction of old pavement. However, the combination of recycling and the reduction of mix manufacture temperatures (warm mixes) raises technical issues about performance and durability of final pavement materials. In order to better predict final properties of these recycled materials, it is also necessary to understand phenomena occurring during the manufacture of recycled asphalt mixtures in the plant. The objectives of the PhD thesis are to understand and identify factors impacting wetting, remobilization and miscibility phenomena existing between organic and inorganic constituents of the bituminous mixture happening during the manufacturing step. The selected experimental approach consists in studying materials interactions according to a physicochemical approach at interfaces and interphases.Concerning wetting mechanisms at the “bitumen/aggregate” interface, some indicators were selected to assess wetting evolutions on a polished mineral slide. The binder ageing influence has also been studied. The bitumen viscosity and asphaltene content influence the wetting quality as well as the surface composition of the mineral substrate. Results have shown that “bitumen/aggregate” wetting evolutions were governed by a model associated to polished, porous and chemically heterogeneous surfaces.Remobilization of the aged binder (at a lower temperature) by the virgin one (heated at 160°C) has been studied at the interface and at the interphase of “aged binder/virgin binder “samples. At the bituminous interface, the spreading time is linearly influenced by the aged binder viscosity. At the bituminous interphase, bituminous sample analysis has shown that a reduction in the binders temperature difference leads to a better blend. Methodologies have been developed to monitor the aged binder migration using techniques such as X-ray micro fluorescence, infrared microscopy in ATR mode and in imaging ATR mode. Infrared microscopy in imaging ATR mode is a suitable technique to monitor the aged binder migration coupled to the carbonyl function marker resulting from the bitumen oxidation and ageing. Results have identified influent parameters corresponding to the aged binder viscosity and chemical composition, as well as the beneficial effect of a rejuvenator on remobilization. The effect of mechanical agitation energy also improves the binders blend. Concerning X-ray micro fluorescence results, binders remobilization has been assessed by the migration of metals which are involved in the bitumen internal composition. Some hypotheses have been proposed to explain observed migration differences of studied markers.Finally, all customized binder-scale methodologies have been applied to the study of road products incorporating virgin aggregates and reclaimed asphalt pavement. Results have shown similarities between observed trends at the microscopic and macroscopic scales. The hot manufacturing process promotes remobilization while the increase in the reclaimed asphalt rate limits it. The increase in the reclaimed asphalt rate also reduces the asphalt mixture homogeneity degree which has been evaluated through the carbonyl function spatial distribution, obtained by a chemical mappings statistical treatment
33
Gao, Xiao. "Tailored interphase structure for improved strength and energy absorption of composites." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 5.63 Mb., 321 p, 2006. http://proquest.umi.com/pqdlink?did=1172119431&Fmt=7&clientId=79356&RQT=309&VName=PQD.
Full text
34
Zhang, Jie [Verfasser], Gert [Akademischer Betreuer] Heinrich, and Chokri [Akademischer Betreuer] Cherif. "Multifunctional composite interphase / Jie Zhang. Gutachter: Chokri Cherif. Betreuer: Gert Heinrich." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://d-nb.info/1067731997/34.
Full text
35
Chen, Carol Chia-Lu. "Interphase histone H3 serine 10 phosphorylation in mouse embryonic stem cells." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62509.
Full text
36
Yang, Zhibing. "Multiphase Contamination in Rock Fractures : Fluid Displacement and Interphase Mass Transfer." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183720.
Full textAbstract:
Multiphase flow and transport in fractured rock is of importance to many practical and engineering applications. In the field of groundwater hydrology an issue of significant environmental concern is the release of dense non-aqueous phase liquids (DNAPLs) which can cause long-term groundwater contamination in fractured aquifers. This study deals with two fundamental processes – fluid displacement and interphase mass transfer – concerning the behavior of the multiphase contaminants in fractured media. The focus of this work has been placed on improving the current understanding of small-scale (single fracture) physics by a combined effort of numerical modeling analysis, laboratory experiments and model development. This thesis contributes to the improved understanding through several aspects. Firstly, the effect of aperture variability, as characterized by geostatistical parameters such as standard deviation and correlation length, on the DNAPL entrapment, dissolution and source-depletion behaviors in single fractures was revealed. Secondly, a novel, generalized approach (adaptive circle fitting approach) to account for the effect of in-plane curvature of fluid-fluid interfaces on immiscible fluid displacement was developed; the new approach has demonstrated good performance when applied to simulate previously published experimental data. Thirdly, the performance of a continuum-based two-phase flow model and an invasion percolation model was compared for modeling fluid displacement in a variable-aperture fracture and the dependence of fracture-scale capillary pressure – saturation relationships on aperture variability was studied. Lastly, through experimental studies and mechanistic numerical modeling of DNAPL dissolution, kinetic mass transfer characteristics of two different entrapment configurations (residual blobs and dead-end pools) were investigated. The obtained understanding from this thesis will be useful for predictive modeling of multiphase contaminant behavior at a larger (fracture network) scale.Flerfasflöde och ämnestransport i sprickigt berg är av betydelse för många praktiska och tekniska problem. Tunga, svårlösliga organiska vätskor (engelska: dense non-aqueous phase liquids: DNAPLs; t.ex. klorerade lösningsmedel) kan orsaka långvarig förorening av vattenresurser, inklusive akviferer i sprickigt berg, och utgör ett viktigt miljöproblem inom grundvattenhydrologin. Denna studie behandlar två fundamentala processer för spridning av flerfasföroreningar i sprickiga medier – utbredning av den organiska vätskan och massöverföring mellan organisk vätska och vatten. Arbetet har fokuserat på att förbättra nuvarande kunskap om de fysikaliska processerna på liten skala (enskilda sprickor) genom en kombination av numerisk modellering, laboratorieexperiment och modellutveckling. Avhandlingen har bidragit till utökad processförståelse i flera avseenden. För det första har arbetet belyst effekterna av sprickaperturens variabilitet, uttryckt med geostatistiska parametrar som standardavvikelse och rumslig korrelationslängd, på fastläggning och lösning av organiska vätskor i enskilda sprickor, samt utmattningsbeteendet hos dessa källor till grundvattenförorening. För det andra har en ny, generell metod (adaptiva cirkelpassningsmetoden) för att ta hänsyn till effekten av krökningen av gränsytan mellan organisk vätska och vatten i sprickplanet utvecklats; denna metod har visats fungera väl i simuleringar av tidigare publicerade experimentella data. För det tredje, har en jämförelse gjorts mellan en kontinuumbaserad tvåfasflödesmodell och en invasions-perkolationsmodell med avseende på hur väl de kan simulera tvåfasflöde i en spricka med varierande apertur. Här studerades även hur relationen mellan kapillärtryck och mättnadsgrad på sprickplansskala beror av variabiliteten i sprickapertur. Till sist undersöktes lösning av den organiska vätskan i grundvatten för två fastläggningsscenarier (fastläggning i immobila droppar och ansamling i fällor – ”återvändssprickor”) både genom experiment och mekanistisk numerisk modellering. Kunskapen som tagits fram i denna avhandling bedöms vara användbar även för att modellera spridningen av flerfasföroreningar på större (spricknätverks-) skalor.
37
Zhang, Yang [Verfasser], and Dieter W. [Akademischer Betreuer] Heermann. "Chromosomes in Interphase and Mitosis / Yang Zhang ; Betreuer: Dieter W. Heermann." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1177888955/34.
Full text
38
Czarnecki, Sebastian [Verfasser]. "Biologically inspired glass/polyepoxide interphase with improved mechanical properties / Sebastian Czarnecki." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1202952267/34.
Full text
39
Sasai, Masaki, Tomoki P. Terada, and Naoko Tokuda. "Dynamical Modeling of Three-Dimensional Genome Organization in Interphase Budding Yeast." Elsevier, 2012. http://hdl.handle.net/2237/20622.
Full text
40
Lane, R. "Studies of load transfer through an interphase in fibre reinforced composites." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339964.
Full text
41
Atkinson, Kirsten Elizabeth. "A study of the interface/interphase in carbon fibre epoxy composites." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243263.
Full text
42
KIRMANN, JEROME. "Metallisation de materiaux composites a matrice organique par interposition d'une interphase." Besançon, 1997. http://www.theses.fr/1997BESA2036.
Full textAbstract:
La difficulte de metalliser les materiaux composites est multiple : heterogeneite du systeme renfort-resine, multiplicite des systemes et des parametres de fabrication, respect de l'integrite du substrat pour les composites de structures. En deposant une interphase metallisable, une partie du probleme est eliminee. Pour l'etude, deux types de composites (verre et carbone/epoxy) et d'interphases (film et poudre de nature epoxyde) ont ete retenus. L'electrolyte utilise est alcalin et a base de permanganate de potassium. Les conditions de decapage sont determinees de facon a ce que l'interphase mise en place protege le substrat composite et que l'adherence d'un revetement de cuivre soit de classe 0 au test de scarification. L'objectif majeur de ce travail a ete de comprendre le role du decapage permanganate sur les deux interphases, tant du point de vue chimique que geometrique, sur l'adherence d'un revetement metallique mesuree par pelage. Du point de vue chimique, des analyses de surface (xps et ir-atr) mettent en evidence la mise a nu des charges minerales incorporees aux interphases. Les oxydations de la chaine carbonee du film et de la poudre sont susceptibles de former des liaisons chimiques entre le revetement de cuivre et le polymere. La mouillabilite des interphases est affecte par la presence de ces charges minerales. La technique de mise en place du film sur le composite influe egalement sur la mesure de l'angle de raccordement (sur echantillon non decape). Du point de vue mecanique, des mesures de resistance au pelage d'un depot de cuivre sont correlees a des criteres caracteristiques de l'amplitude verticale moyenne de la rugosite (r#z) et de sa morphologique (s#k,e#k). L'outil metrologique consiste en une technique de mesure tridimensionnelle d'etat de surface couplee a une localisation precise d'une meme zone tout au long du decapage afin de suivre l'evolution micro-geometrique des deux interphases.
43
Huang, Hui. "Electrochemical Application and AFM Characterization of Nanocomposites : Focus on Interphase Properties." Doctoral thesis, KTH, Yt- och korrosionsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203239.
Full textAbstract:
The use of graphene and conductive polyaniline nanomaterials in the field of electrochemistry is increasing due to their excellent conductivity, rapid electron transfer and high specific surface area. However, these properties are strongly dependent on the preparation processes. To accelerate the development of advanced electrochemical sensors for the simultaneous detection of trace amounts of heavy metal ions, two facile and green methods are proposed to improve their performance in this thesis. The first one was dedicated to make graphene-carbon nanotube hybrid nanocomposites. The introduction of carbon nanotubes not only greatly enhances the conductivity of graphene but also suppresses, to some degree, the aggregation between graphene nanosheets. Another method proposed in this thesis work was to synthesize a phytic acid doped polyaniline nanofiber based nanocomposite. The synergistic contribution from polyaniline nanofibers and phytic acid enhances the accumulation efficiency and the charge transfer rate of metal ions during the differential pulse anodic stripping voltammetry analysis. The above-mentioned nanocomposite modified electrodes were all successfully applied to real samples for the simultaneous detection of Cd2+ and Pb2+ with good recovery rates. Meanwhile, corrosion protection is another important branch in the field of electrochemistry. In this direction, an active alkyd-polyaniline composite coating with self-healing functionality was prepared. The polyaniline used in this thesis was doped with p-toluene sulfonic acid, which was employed to increase the conductivity of polyaniline, and 1 wt.% of as-prepared polyaniline nanoparticles were found to offer an effective conductive network for anticorrosion. Finally, the reasons that such low loading levels of nanomaterials can result in significantly reinforced properties in nanocomposites were studied with combined atomic force microscopy (AFM) techniques. The results demonstrated that the interphase for a 40-nm-sized silica particle could extend to 55–70 nm in poly(ethyl methacrylate) (PEMA) and poly(isobutyl methacrylate) (PiBMA) polymer matrix, and the interphase exhibited a gradient distribution in surface nanomechanical properties.QC 20170315
44
Delpouve, Héloïse. "Relation microstructure et épaisseur d’une interphase BN et ses propriétés mécaniques." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0197/document.
Full textAbstract:
L’utilisation des composites à matrice céramiques (CMC), et particulièrement les matériaux SiC/SiC, à la place des alliages métalliques dans les moteurs aéronautiques peut permettre de réduire leur consommation. Ils possèdent en effet des propriétés physiques et mécaniques très intéressantes à haute température : faible densité, résistance élevée aux chocs thermiques et rupture non-fragile. Dans ces matériaux, une fine couche est insérée entre les fibres et la matrice : l’interphase. Le nitrure de bore pyrolytique est le matériau d’interphase de choix pour les applications visées. La bibliographie souligne bien la nécessité et la difficulté de « contrôler » l’intensité des liaisons interfaciales fibres/matrice (F/M) grâce à l’interphase. Mais l’influence exacte de la cristallinité et de l’épaisseur des interphases de type BN sur son contrôle, et par conséquent sur le comportement mécanique final du CMC industriel est encore mal connue.Une première problématique abordée dans cette thèse est l’échelle du CMC de laboratoire à utiliser. En effet jusqu’ici, les matériaux modèles les plus couramment employés sont les mini- et les micro- composites 1D. Ils peuvent être élaborés facilement et rapidement par dépôt chimique en phase vapeur mais ne rendent pas compte de phénomènes inévitablement présents au sein du composite industriel. C’est pourquoi l’utilisation de nouveaux matériaux modèles 2D comme les « monostrates » comprenant un pli de tissu, l’interphase BN et une matrice de SiC dont la porosité peut être comblée par du Si comme dans le cas des CMC industriels est plus pertinente et est proposée. Cependant, de par la faible épaisseur des éprouvettes, les protocoles de caractérisation et de tests mécaniques ont dû être revus. Il s’agit notamment de caractériser la liaison F/M par deux paramètres : la contrainte de cisaillement de la liaison interfaciale (τi) et le module de cisaillement du matériau (G12).Pour la partie mécanique, des essais de traction monotone et cyclée dans l’axe des fibres du renfort (exploités à l’aide de modèles micromécaniques), des essais de cisaillement Iosipescu, ainsi que des essais de push out ont été mis au point et exploités. Des analyses de micro caractérisation par microscopie électronique (MEB, FIB-MEB, MET) ont été réalisées avant et après essais mécaniques avec des interphases de différentes configurations afin de relier les différences de microstructures et d’épaisseurs aux chemins de fissuration matricielle et aux comportements mécaniques macroscopiques des composites. La liaison F/M la plus forte est notamment obtenue quand le degré de cristallisation et l’anisotropie structurale du BN sont peu élevés, pourvu que l’épaisseur de l’interphase soit suffisanteThe use of ceramic matrix composites (CMC), and particularly SiC/SiC materials, in place of metal alloys in aircraft engines has the potential to reduce their fuel consumption. They have very interesting physical and mechanical properties at high temperatures: low density, high resistance to thermal shock and non- brittle failure. In these materials, a thin layer is inserted between the fibres and the matrix: the interphase. Pyrolytic boron nitride is the interphase material of choice to achieve the desired applications. The bibliography clearly highlights the need and difficulty of "controlling" the intensity of fibre/matrix interfacial bonds (F/M) thanks to the interphase. But the exact influence of the crystallinity and thickness of BN-type interphases on its control, and consequently on the final mechanical behaviour of the industrial CMC, is still insufficiently known.A first issue addressed in this thesis is the scale of the CMC to be used in the laboratory. Indeed, so far, the most commonly used model materials are 1D mini and micro composites. They can be easily and quickly prepared by chemical vapour deposition but do not account for phenomena inevitably present in the industrial composite. Therefore, the use of new 2D model materials such as "monostrates" comprising a single-ply woven, the BN interphase and a SiC matrix in which the porosity can be filled with Si as in the case of industrial CMCs is more relevant and is proposed. However, due to the thinness of the specimens, the characterization and mechanical testing protocols had to be reviewed. This involves characterizing the F/M bond by two parameters: the shear stress of the interfacial bond (τi) and the shear modulus of the material (G12).For the mechanical part, monotonic and cycled tensile tests in the fibre axis of the reinforcement (operated using micromechanical models), Iosipescu shear tests, as well as push-out tests were developed and used. Micro characterization analyses by electron microscopy (SEM, FIB-SEM, TEM) were performed before and after mechanical tests with interphases of different configurations in order to link the differences in microstructures and thicknesses to the matrix cracking paths and macroscopic mechanical behaviours of the composites. The strongest F/M bond is obtained notably when the degree of crystallization and structural anisotropy of the BN are low, provided that the interphase is thick enough
45
Leversha, Margaret Anne. "Cytological estimations of molecular genetic difference : applications and implications of fluorescence in situ hybridisation mapping in the long arm of human chromosome 9." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337902.
Full text
46
Gardner, Slade Havelock II. "An Investigation of the Structure-Property Relationships for High Performance Thermoplastic Matrix, Carbon Fiber Composites with a Tailored Polyimide Interphase." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30757.
Full textAbstract:
The aqueous suspension prepregging technique was used to fabricate PEEK and PPS matrix composites with polyimide interphases of tailored properties. The structure-property relationships of Ultem-type polyimide and BisP-BTDA polyimide which were made from various water soluble polyamic acid salts were studied. The molecular weight of the polyimides was shown to be dependant upon the selection of the base used for making the polyamic acid salt. The development of an Ultem-type polyimide with controlled molecular weight and properties similar to commercial Ultem 1000 was accomplished with the Ultem-type TPA+ polyamic acid salt. Both the Ultem-type polyimides and the BisP-BTDA polyimides derived from the NH4+ salt and the TMA+ salt were shown to crosslink at elevated temperatures.
Blends of Ultem-type polyimide with PEEK and BisP-BTDA polyimide with PEEK were prepared to study the structure-property relationships of model composite matrices. Since both polyimides are miscible with PEEK, interdiffusion of the polyimides with PEEK is expected, however, the interdiffusion behavior is complicated by the crosslinking mechanism of the polyimides.
Ultem-type polyimide interphase, PEEK matrix composites and BisP-BTDA polyimide interphase, PEEK matrix composites were fabricated using the aqueous suspension prepregging technique and evaluated to determine the effects of the interphase properties on the bulk composite performance and durability. Three different Ultem-type polyimides from the NH4+, TMA+ and TPA+ polyamic acid salts were used and two different BisP-BTDA polyimides from the NH4+ and TMA+ polyamic acid salts were used. The transverse flexure strength was used to qualitatively rank the composites by level of interfacial shear strength. The longitudinal tensile strength of the composites was shown to vary with relative interfacial shear strength. The trend of these data qualitatively support the existence of a maximum longitudinal tensile strength at an optimum interfacial shear strength. Notched fatigue testing of the Ultem-type polyimide interphase, PEEK matrix composites showed that the initial split growth rate increased with decreasing relative interfacial shear strength.
Ultem-type polyimide interphase, PPS matrix composites were fabricated using the aqueous suspension prepregging technique and evaluated to determine the effects of the interphase properties on the bulk composite performance. Three different Ultem-type polyimides from the NH4+, TMA+ and TPA+ polyamic acid salts were used. The transverse flexure strength was used to qualitatively rank the composites by level of interfacial shear strength. The longitudinal tensile strength of the composites was shown to vary with relative interfacial shear strength. The trend of these data qualitatively support the existence of a maximum longitudinal tensile strength at an optimum interfacial shear strength.Ph. D.
47
Mercier, Dimitri. "Étude des mécanismes de formation de l'interphase dans les systèmes époxy-amine/aluminium." Paris 12, 2006. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990003939410204611&vid=upec.
Full textAbstract:
Dans les systèmes collés ou peints époxy-amine / aluminium, la mise en contact du liquide polymérique sur le substrat métallique, provoque, par dissolution de l'oxyde de surface par les groupements amine du durcisseur aminé, la formation d'une zone modifiée appelée interphase. Les propriétés finales de ces systèmes dépendent fortement des caractéristiques de cette interphase. Pourtant les molécules aminées sont reconnues et utilisées comme inhibiteurs dans les problèmes de corrosion. L'étude de l'interaction d'une molécule aminée simple (le 1,2-diaminoéthane) avec un substrat d'aluminium a permis de mettre en évidence un double effet sur le substrat. En effet la molécule peut former un complexe de sphère interne bidentate mononucléaire instable (adsorption des deux pôles amines sur le même cation métallique) provoquant la dissolution du substrat et permettant d'expliquer le phénomène de formation de l'interphase dans les systèmes époxy-amine / aluminium. Par ailleurs, cette molécule peut former des complexes stables de sphère externe (monodentate ou bidentate) qui permet, dans certaines conditions, la protection du substratWhen they are applied onto aluminium substrates, epoxy-amine liquid monomers react with the oxide-covered metal to form an interphase by dissolution of the oxide layer by amine hardener. This interphase is of particular interest to determine the physical and chemical properties of the bondary (practical adhesion, corrosion resistance and durability). On the other hand diamine molecules are often used as inhibitors of corrosion. The study of the interaction of 1,2-diaminoethane (molecule used as amine curing agent and inhibitor) with aluminium susbstrate has displayed different effects of the molecule on the substrate. The diamine molecule can form a mononuclear inner-sphere complex (bidentate). This complex is not stable and leads to the dissolution of the substrate thus explaining the formation of the interphase. On the other hand the diamine molecule can form a binuclear outer-sphere complex (monodentate or bidentate). This complex is very stable and can protect the substrate
48
Vlasie-Belloncle, Valentina. "Modélisation mécanique et caractérisation ultrasonore de structures collées." Paris 6, 2003. http://www.theses.fr/2003PA066497.
Full text
49
Lacrampe, Valérie. "Influence du type d'ensimage sur la nature des zones interfaciales dans les matériaux composites polyépoxy/fibres de verre." Lyon, INSA, 1992. http://www.theses.fr/1992ISAL0068.
Full textAbstract:
La spectrométrie mécanique dynamique est utilisée pour mettre en évidence les interfaces ou interphases fibres de verre/matrice époxy-anhydride dans des composites unidirectionnels. Des fibres de verre ont été ensimées à partir d'émulsions aqueuses à base de divers agents collants et d'un agent de couplage unique (gamma- aminopropyl- triéthoxysilane). Les caractéristiques viscoélastiques des ensimages sont étudiées séparément sont étudiées séparément par analyse de films (obtenus par séchage des émulsions), de fibres ensimées et de modèles plans (lames de verre ensimées) simulant ces dernières. Une étude comparative met en évidence les réactions chimiques entre agents collants et silane et démontre la présence d'interactions chimiques et physiques entre verre/agent collant/silane. Une modélisation plane des composites unidirectionnels est effectué et met en évidence une structure différente de la matrice en masse et au voisinage du renfort, ainsi que la possibilité de réactions chimiques entre ensima e et matrice dans certains cas. Ces résultats sont confirmés par l'étude des composites unidirectionnels. Enfin une tentative de corrélation est réalisée entre les propriétés mécaniques dynamiques et statiques des composites unidirectionnelsDynamic mechanical analysis is used to highlight epoxy-anhydride matrix/glass fibres interfaces or interphase in unidirectional composites. Glass fibres have been sized from aqueous emulsions made of several polymer coating and only one silane coupling agent (y-Amino propyltriethoxysilane). The viscoelastic characteristics of sizing are separately achieved first on films analysis obtained from dried emulsions ; then on sized fibres, and lastly on a plane model composed of sized glass plates which simulate sized fibres. Plane model of unidirectional composite is done and bas shown that the structure. Around the fibre and in the bulk matrix are different. More over through this modelling, reactions between matrix and sizing can occur in some cases. Then we have tried to correlate static and dynamic mechanical properties of unidirectional composites
50
Holder, Elisabeth. "Polysiloxanes with luminescent molecular probes synthesis, characterization and application of ordered and non-ordered structures /." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9986608.
Full text