Dissertations / Theses: 'Morphology of stem'

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O'Meara, John 1954. "Delaware stem morphology." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39236.

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The derivational morphology of Munsee Delaware, an Eastern Algonquian language spoken in southwestern Ontario, is analysed and described. Chapter I presents general information about Delaware, including a summary of grammatical information necessary for the understanding of word structure. The theoretical constructs assumed are summarized. A distinction is made between primary derivation, in which suffixes are attached to roots (and affixes) to form stems; and secondary derivation, in which suffixes are attached to stems to form new stems. Inflectional affixes are attached to stems which are formed in primary or secondary derivation. Chapter II discusses verb-forming suffixes ('finals') added to roots and certain suffixes to form verb stems. Chapter III discusses verb-forming suffixes which attach to existing noun and verb stems to form verb stems (secondary derivation). Chapter IV discusses 'medials', which prototypically occur between roots and 'final' suffixes. Chapter V discusses noun-forming suffixes which are attached to roots and medials. Chapter VI discusses noun-forming suffixes which attach to existing noun and verb stems to form noun stems (secondary derivation). Chapter VII discusses bound variants of noun stems, morphological elements which occur as members of morphologically complex noun stems.

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Partridge, Roland William. "Morphogenesis and morphology of intestinal villi." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28884.

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Paediatric intestinal failure following bowel resection causes significant morbidity and mortality. There is a pressing need for improved treatment modalities. Following loss of bowel, the remaining intestine undergoes a period of adaptation, characterised by an increase in height of the intestinal villi. Better understanding the factors that govern the formation and growth of villi may lead to therapeutic interventions that amplify the intrinsic adaptation response. This thesis aims to explore the processes by which intestinal villi form during embryological development, the contribution of intestinal stem cells to this, and candidate signalling pathways that may yield insights into new therapeutic interventions for patients with intestinal failure. Abstract: Aim I will examine the morphogenesis and morphology of intestinal villi by investigating three themes: 1) Villus morphogenesis: When and where do villi form along the gut tube? Can this process be quantified, both in vivo and in vitro? Is this initiated by a dominolike signaling-cascade along the bowel, or location-specific intrinsic triggers? 2) Stem cells: What is the spatiotemporal appearance of the Lgr5-expressing intestinal stem cells during development? How does this relate to the process of villus morphogenesis? 3) Signalling pathways: Can a genetic mutation mouse model help elucidate pathways by which post bowel resection adaptation might occur? Can this be used to help identify potential intestinotrophic agents? Abstract: Materials and Methods Three mice models were used as the foundation for this work. Embryonic tissue was analysed from wild-type CD1 and Lgr5-eGFP-IRES-CreERT2 mice, and adult intestinal tissue examined from tamoxifen-activated Villin-Cre-ERT2 Pten-/- Brafv600E mice. Culture of wild-type embryonic mouse intestine with and without segments removed and / or reversed was performed to investigate the question of what triggers the proximal-to-distal wave of villus morphogenesis. Immunohistochemical interrogation using anti-GFP antibodies was used in the Lgr5- GFP mice to identify the location of Lgr5-expressing cells during the development of villi. Bright-field microscopy, time-lapse in-incubator microscopy, and histological sections assessed villus morphology. The Villin-Cre-ERT2 Pten-/- Brafv600E mouse mutant was explored regarding the intestinal epithelial morphometric changes that occur following tamoxifen-induction. Abstract: Results The proximal-to-distal wave of villus morphogenesis was observed both in vivo and in vitro. Villus morphogenesis commences at embryonic day 14.5 in vivo and after three days in culture from e11.5 in vitro. The villus structures formed in vitro are significantly attenuated compared to in vivo development. An attempt was made to overcome this by providing intestinal explants with a blood supply to aid growth. Evidence is presented that suggest the proximal-to-distal wave of villus morphogenesis is driven by location specific factors intrinsic to each part of the bowel, rather than a domino-like signalling cascade travelling along the intestine. Lgr5-expressing intestinal stem cells were present in early development. Prior to villus morphogenesis they were uniformly distributed along the luminal surface of the intestinal epithelia. During the intense proliferation associated with villus morphogenesis they progressively congregated to the inter-villus spaces. Once villi are fully formed they were absent from the villi but identified in the inter-villus spaces. The Pten/Braf mouse mutant demonstrates villus morphological changes similar to those found following post-bowel resection adaptation. This suggests that there may be a role for Pten/Braf in the epithelial proliferation following extensive bowel resection. Signalling factors in these pathways may be candidate intestinotrophic agents for the treatment of short bowel syndrome. Abstract: Conclusions Before any processes that manipulate intestinal epithelia can be safely translated into therapies to aid adaptation in patients with intestinal failure, it is important to have a full and detailed understanding of the basic science principles that underpin the behaviour of the epithelial cells, both during development and in adulthood. I have explored and quantified the process of villus morphogenesis in the embryonic mouse, investigated the timing of appearance of Lgr5 intestinal stem cells, and interrogated a genetic mouse model with morphometric changes similar to those seen following small bowel resection. I propose two candidate intestinotrophic agents that may hold regenerative potential to augment post small bowel resection adaptation. The next stage of investigation would be to use a mouse model of small bowel resection with manipulation of cell signalling factors to assess impact on post resection adaptation. The ultimate goal would be to investigate epithelial activity in human neonatal intestine and explore methods of modulating this to improve the outcomes from post bowel resection intestinal failure.

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Roshan, Amit. "Stochasticity and order : studies of keratinocyte proliferation." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/252966.

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A central tenet of stem cell biology has been that proliferating tissues are maintained through a cellular hierarchy comprising of self-renewing stem cells at the apex, multiple lineage-restricted short-lived progenitor cells, and post-mitotic differentiated cells. The wide range of colony sizes in cultured human keratinocytes has been taken to support this hypothesis. Contrary to this model, researchers using genetic lineage tracing in mouse epidermis have inferred a single progenitor population for homeostasis, and a quiescent stem cell population activated upon wounding or genetic mutation. To study the proliferative behaviour of human keratinocytes, I used live imaging in vitro at single cell resolution. This shows two modes of proliferation: Type 1 cell division is stochastic with equal odds of generating dividing or non-dividing progeny, while Type 2 cell division predominantly produces two dividing daughters. These two modes are sufficient to explain the entire range of colony sizes seen after 7-12 days of culture and does not require a spectrum of proliferative ability. This insight provides a simple way to study the effects of external factors on cell fate. To exemplify this, I observed the effects of epidermal growth factor (EGF) and the Wnt agonist R-spondin on proliferation. Here I find proliferation in type 2 colonies changes by changing the proportion of cells dividing. This has implications for the limited success of EGF therapies in clinical trials following burns. To examine clonal contributions to wound repair, I used the mouse oesophageal epithelium which is exclusively composed of, and maintained by, a single progenitor population. I developed a micro-endoscopic wounding technique that produced localised superficial wounds. Here, I found that these wounds healed by uniform contribution from surrounding keratinocytes, demonstrating that reserve stem cells are not obligatory for wound repair. In summary, my work shows that human keratinocytes in vitro have two, and only two, modes of proliferation: a stochastic mode that is insensitive to external EGF signalling, and a EGF-sensitive exponential mode. Additionally, proliferation during wound repair can occur with stochastically dividing progenitors, and does not obligate stem cell recruitment in vivo.

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Siddiqi, Daniel A. "Minimize Exponence: Economy Effects on a Model of the Morphosyntactic Component of the Grammar." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/194752.

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Working within the morphosyntactic framework of Distributed Morphology (DM, Halle and Marantz 1993, 1994) within the Minimalist Program (Chomsky 1995), this dissertation proposes a new economy constraint on the grammar, MINIMIZE EXPONENCE, which selects the derivation that realizes all its interpretable features with the fewest morphemes. The purpose of this proposal is to capture the conflicting needs of the grammar to be both maximally contrastive and maximally efficient.I show that the constraint MINIMIZE EXPONENCE has a number of effects on analyses of morphosyntactic phenomena. I propose that, in order to satisfy MINIMIZE EXPONENCE, the roots in a derivation fuse with the functional heads projected above them, resulting in a simplex head that contains both a root and interpretable features. Following the tenets of DM, this head is now a target for the process of Vocabulary insertion. Since the target node contains both content and functional information, so too can Vocabulary Items (VIs) be specified for both types of information. This allows VIs such as eat and ate to compete with each other. This competition of forms linked to the same root allows for a new model of root allomorphy within the framework of DM. In this model of root allomorphy, following proposals by Pfau (2000), VIs that realize roots participate in competition in the same was as do VIs that realize abstract morphemes. Since root VIs are participating in competition and are specified for both content and formal features, the need for licensing through secondary exponence as proposed by Harley and Noyer (2000) is removed from the framework. Further, since eat and ate in this model are different VIs with different specifications that compete with each other for insertion, this model of root allomorphy also eliminates the need for readjustment rules as proposed by Halle and Marantz (1993, 1994) and elaborated on by Marantz (1997). This new model of root allomorphy allows for an account of the blocking of regular inflection in English nominal compounds (e.g. *rats-catcher), which was problematic for theorists working with DM, given the tenets of the framework.I also show that the fusion of roots and functional elements driven by MINIMIZE EXPONENCE allows for a new account of subcategorization. The model of subcategorization presented here falls out of the following facts: 1) arguments are introduced by functional heads; 2) those heads fuse with the root they are projected above, resulting in the node containing both the root and the features of the functional heads; 3) since the root now contains both the root and the formal features, the corresponding VI can be specified for both; 4) VIs that realize roots can also be specified for compatibility or incompatibility of the features of the functional heads that license argument structure. The result here is an underspecification model of subcategorization that predicts a number of behaviors of verbs with respect to their argument structure that it is difficult for a full specification model to account for. Those include polysemy (I ran the ball to Mary) and structural coercion (I thought the book to Mary).

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Heintz, Ilana. "Arabic Language Modeling with Stem-Derived Morphemes for Automatic Speech Recognition." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275053334.

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Boone, Jason Nathaniel 1976. "Characterization of novel neural stem cell populations in the Drosophila central nervous system." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8160.

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xi, 88 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
Neuroblasts are the neural stem cells of the Drosophlia central nervous system. They are large cells that divide asymmetrically to renew another neuroblast and generate a smaller ganglion mother cell (gmc) that will divide once to produce two neurons. Combining genetic lineage tracing experiments with cell fate markers I isolated two separate neural stem cell populations with distinct locations and cellular behaviors in the larval brain. In my first chapter I introduce the central nervous system of Drosophila and in the next two sections of chapter I, I introduce the development of the optic lobe and central brain, two separate structures of the central nervous system. In my second chapter I characterize the lineage relationship of cells within the developing larval optic lobe and use cell fate markers to determine the identity of these cells. Next I examine the effect of spindle orientation on cell fate within epithelial cells of the optic lobe. In my third chapter I characterize another novel neural stem cell lineage in the larval brain containing GMCs with greater proliferation potential than a "canonical" GMC, and I term these, transit amplifying gmcs (TA-GMCs). Further I show that the parent neuroblast of these novel TA-GMCs does not asymmetrically segregate the fate determinant Prospero (Pros) thereby producing a GMC with greater proliferation potential. Finally I show that TA-GMCs do asymmetrically segregate the fate determinant Pros, divide slowly and give rise to up to 10 neurons which normal gmcs never do. In my fourth chapter I show preliminary work on the characterization of a mutation that causes excessive production of neuroblasts specifically in novel TA-GMC lineages. These findings reveal novel neural stem cell lineages, patterns of asymmetric cell division and patterns of neurogenesis that could aid in our understanding of neural stem cell biology and tumorogenesis. This dissertation includes both my previously published and my co-authored materials.
Adviser: Chris Doe

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Lanci, Aliai <1987&gt. "Morphology and Microscopy of Equine Umbilical Cord and Characterization of Mesenchymal Stem Cells Isolated from Foetal Adnexa." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7890/1/TESI%20DOTTORATO%20ALIAI%20LANCI.pdf.

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The purpose of this PhD thesis is to perform a dissertation about the equine umbilical cord (UC), with particular attention to its macroscopic characteristics moving into its microscopic features. Furthermore, equine UC was microscopically and immunohistochemically described. The coiling makes the UC a structure both flexible and strong, and provides resistance to external forces, which could compromise blood flow. Data obtained from the present study could be considered as a normal range of number of coils and UCI in the equine physiological pregnancies. The second and major component of this dissertation was focused on umbilical cord as a Mesenchymal Stem Cells (MSCs) niche. In particular, the ultrastructural characterization and immune profile of equine MSCs derived from foetal tissues (Wharton’s jelly and blood) were investigated; equine foetal MSCs were then compared to human foetal MSCs and equine adult MSCs. The third section included the clinical applications of MSCs derived from AF and WJ on cutaneous wounds of different ages’ foals. The employ of foetal MSCs on cutaneous wounds decreased their healing both in neonatal foals and six-month foals, in comparison with other traditional treatments. In conclusion, one of the most important feature of placenta’s evaluation is the observation of normal characteristic of the equine UC. Furthermore, since the UC is a discarded material after delivery, it represents an excellent non-invasive alternative source of MSCs with reliable migration and differentiation capacities, and it is a convenient cell source for autologous or allogeneic regenerative therapies. Finally, it is important a constant update about regenerative medicine and the development of research in this field considering that the horse serves as a perfect model for humans.

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Koch, Britta. "Scaffold dimensionality and confinement determine single cell morphology and migration." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-194717.

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This thesis describes a highly interdisciplinary approach to discern the differing impact of scaffold dimensionality and physical space restrictions on the behavior of single cells. Rolled-up nanotechnology is employed to fabricate three-dimensional (3D) SiO/SiO2 microtube geometries of varied diameter, that after a biofunctionalization step are shown to support the growth of U2OS and six different types of stem cells. Cell confinement quantifiable through the given microtube diameter is tolerated by U2OS cells through a remarkable elongation of the cell body and nucleus down to a certain threshold, while the integrity of the DNA is maintained. This confinement for NSPCs also leads to the approaching of the in vivo morphology, underlining the space-restrictive property of live tissue. The dimensionality of the cell culture scaffold however is identified as the major determiner of NSPC migration characteristics and leads to a morphologically distinct mesenchymal to amoeboid migration mode transition. The 3D microtube migration is characterized by exclusively filopodia protrusion formation, a higher dependence on actin polymerization and adopts aspects of in vivo-reported saltatory movement. The reported findings contribute to the determination of biomaterial scaffold design principles and advance our current understanding of how physical properties of the extracellular environment affect cell migration characteristics.

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Yu, Leqian. "The Effect of Micro and Nano Mechanical Environment on Pluripotent Stem Cells." Kyoto University, 2017. http://hdl.handle.net/2433/227624.

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Demir, Özlem. "Functional Characterization of Microtubule Associated Proteins in ES Cell Division and Neuronal Differentiation." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-163103.

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Microtubules are tubular polymers that are involved in a variety of cellular processes such as cell movement, mitosis and intracellular transport. The dynamic behavior of microtubules makes this possible because all of these processes require quick responses. Embryonic stem (ES) cells were first isolated from mouse embryos and they have two unique characteristics; they can be kept undifferentiated for many passages with a stable karyotype and they can be differentiated into any type of cells under appropriate conditions. The pluripotency of ES cells, their ease of manipulation in culture, and their ability to contribute to the mouse germ-line provides us a model of differentiation both in vitro and in vivo. In my thesis I focused on the cell division and neuronal differentiation of ES cells and developed two methods to understand the effects of microtubule dynamics in spindle assembly and chromosome segregation and to reveal the roles of different Microtubule Associated Proteins (MAPs) in the neuronal morphology formation. In the first part, we developed a live-cell imaging method for ES cells to visualize, track and analyze the single cell behavior in a cell population over a time period. So far many techniques have been adapted and combined for imaging of cell lines, mainly for the cancer or immortalized ones. However, because ES cells are very prone to apoptosis, tend to form spheres and hard to stably label, it is quite tricky to image them in culture conditions. In our system, we combined the BAC-based gene expression with wide-field deconvolution microscopy for ES cells that are plated onto the laminin-511 coated surface and kept in CO2 independent culture conditions. This combined technique does not interfere with the growth of cells and keeps them healthy up to 24 hours on the microscope stage. In the second part, we analyzed the effects of MAPs chTOG, EB1, Kif18A and MCAK in the overall spindle morphology and mitotic progression in mES cells. For this purpose, we utilized our stable TUBB-GFP and H2A-GFP cell lines along with our live-cell imaging set-up to reveal the effects of the above-mentioned proteins and the interplay among each other. By using RNAi method we either single or co-depleted the genes by siRNAs and measured the spindle length and width in RNAi conditions. We further analyzed the mitotic progression in H2A-GFP cell line in terms of the metaphase timing and the percentage of chromosome segregation errors. Our results showed that, EB1 depletion did not cause any significant changes in the overall spindle morphology or in the metaphase timing. However, the co-depletion of EB1 with chTOG partially rescued the sichTOG specific mini-spindle phenotype. siKif18A produced longer spindles without any change in the spindle width. Surprisingly, the co-depletion of antagonistic chTOG and Kif18A proteins had additive effects on the spindle dynamics and on mitotic progression in a way that spindle assembly was severely disrupted by the absence of these two proteins and as a result of this, both metaphase timing and chromosome missegregation levels increased significantly. These results overall indicate that MAPs have important roles in the regulation of dynamic instability and these proteins have an interplay among each other to be able to control the morphology of the spindle as well as the correct segregation of chromosomes into daughter cells. In the last part, I will introduce you a new ES cell based differentiation and morphology model, which brings the advantages of high resolution imaging capacity, control over development and easy genetic manipulation and culturing. We have generated Tet-induced shRNA cell lines against chTOG, Kif18A and MCAK, which are also stably expressing TUBB-GFP. These labeled cells were mixed with unlabeled wild-type mES cells before differentiation at 1:1000 ratio and then they were differentiated into mouse cortical cells and spinal motor neurons. Our results showed that, all of the three genes could be successfully knocked-down by shRNA after 48 hours of Tet induction. After mixing the labeled and unlabeled cells, single neurons could be imaged at high resolution and their skeletons could be generated afterwards. The RNAi studies in shchTOG cell line showed that, the knock-down of this gene in early differentiation interferes with the neuronal differentiation.

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Strawbridge, Stanley Eugene. "Understanding the dynamics of embryonic stem cell differentiation." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287576.

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The two defining features of mouse embryonic stem (ES) cells are self-renewal and naive pluripotency, the ability to give rise to all cell lineages in the adult body. In addition to being a unique and interesting cell type, pluripotent ES cells have demonstrated their potential for continued advancements in biomedical science. Currently, there is an improved understanding in the chemical signals and the gene regulatory network responsible for the maintenance of ES cells in the naive pluripotent state. However, less is understood about how ES cells exit pluripotency. My main aim is to study the dynamics and the factors affecting the irreversible exit from pluripotency. Expression of the reporter Rex1-GFPd2, which is inactivated upon exit from naive pluripotency, was analyzed by quantitative long-term single-cell imaging over many generations. This technique allowed chemical, physical, and genealogical information to be recorded during the transition to exit. Culture conditions that provided homogeneous populations were used in all assays and these data were validated against bulk-culture data where appropriate. Changes in real-time cell behavior were seen in cell-cell contact, motility, and cell-cycle duration. Undifferentiated ES cells form tightly joined colonies, with cells that exhibit low motility and a constant cell-cycle duration. Exit is associated with increasing cell motility, decreased cell-cell contact, and an acceleration in cell proliferation. The onset of exit is associated with a sudden and irreversible inactivation of the Rex1-GFPd2 reporter. This inactivation is asynchronous, as it occurs at different times and in different generations during ES cell differentiation. However, examination of daughter cells generated from the same mother revealed a high level of synchronicity. Further investigation revealed that high levels of correlation in cell-cycle duration and Rex1-GFPd2 expression exist between differentiating sister and cousin cells, providing strong evidence that cell potency is inherited symmetrically in cell divisions during exit $\textit{in vitro}$. How cells change fate is a fundamental question in developmental biology. Knowing the cellular dynamics during the transition out of naive pluripotency is important for harnessing the potential of ES cells and understanding how cell fate decisions are made during embryonic development. The quantification of the timing of exit from naive pluripotency coupled with identifiable changes in cellular behaviors, such as motility, cell size, and cell-cycle duration, enhances the understanding of how cell fate changes are regulated during directed differentiation.

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Yuvaraj, Padhmavathy. "Role of Smad4 in the Morphological and Migratory properties of Mouse Trophoblast stem cells." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1310755757.

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Rajasimha, Harsha Karur. "Insights Into Mitochondrial Genetic and Morphologic Dynamics Gained by Stochastic Simulation." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29961.

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MtDNA mutations in mammalian cells are implicated in cellular ageing and encephalomyopathies, although mechanisms involved are not completely understood. The mitochondrial genetic bottleneck has puzzled biologists for a long time. Approximate models of genetic bottleneck proposed in the literature do not accurately model underlying biology. Recent studies indicate mitochondrial morphology changes during cellular aging in culture. In particular, the rates of mitochondrial fission and fusion are shown to be in tight balance, though this rate decreases with age. Some proteins involved in mitochondrial morphology maintenance are implicated in apoptosis. Hence, mitochondrial genetic and morphologic dynamics are critical to the life and death of cells. By working closely with experimental collaborators and by utilizing data derived from literature, we have developed stochastic simulation models of mitochondrial genetic and morphologic dynamics. Hypotheses from the mitochondrial genetic dynamics model include: (1) the decay of mtDNA heteroplasmy in blood is exponential and not linear as reported in literature. (2) Blood heteroplasmy measurements are a good proxy for the blood stem cell heteroplasmy. (3) By analyzing our simulation results in tandem with published longitudinal clinical data, we propose for the first time, a way to correct for the patient's age in the analysis of heteroplasmy data. (4) We develop a direct model of the genetic bottleneck process during mouse embryogenesis. (5) Partitioning of mtDNA into daughter cells during blastocyst formation and relaxed replication of mtDNA during the exponential growth phase of primordial germ cells leads to the variation in heteroplasmy inherited by offspring from the same mother. (6) We develop a “simulation control” for experimental studies on mtDNA heteroplasmy variation in cell cultures. Hypothesis from the mitochondrial morphologic dynamics model: (7) A cell adjusts the mitochondrial fusion rate to compensate for the fluctuations in the fission rate, but not vice versa. A deterministic model for this control is proposed. Contributions: extensible simulation models of mitochondrial genetic and morphologic dynamics to aide in the powerful analysis of published and new experimental data. Our results have direct relevance to cell biology and clinical diagnosis. The work also illustrates scientific success by tight integration of theory with practice.
Ph. D.

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Watanabe, Naoki. "Hbp1 regulates the timing of neuronal differentiation during cortical development by controlling cell cycle progression." Kyoto University, 2015. http://hdl.handle.net/2433/200496.

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Comez, Murat Ali. "Large Vocabulary Continuous Speech Recogniton For Turkish Using Htk." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1205491/index.pdf.

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This study aims to build a new language model that can be used in a Turkish large vocabulary continuous speech recognition system. Turkish is a very productive language in terms of word forms because of its agglutinative nature. For such languages like Turkish, the vocabulary size is far from being acceptable. From only one simple stem, thousands of new word forms can be generated using inflectional or derivational suffixes. In this thesis, words are parsed into their stems and endings. One ending includes the suffixes attached to the associated root. Then the search network based on bigrams is constructed. Bigrams are obtained either using stem and endings, or using only stems. The language model proposed is based on bigrams obtained using only stems. All work is done in HTK (Hidden Markov Model Toolkit) environment, except parsing and network transforming. Besides of offering a new language model for Turkish, this study involves a comprehensive work about speech recognition inspecting into concepts in the state of the art speech recognition systems. To acquire good command of these concepts and processes in speech recognition isolated word, connected word and continuous speech recognition tasks are performed. The experimental results associated with these tasks are also given.

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Oliveira, Inez Vilar de Morais [UNESP]. "Propagação e diferenciação floral do abacateiro." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/105226.

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Made available in DSpace on 2014-06-11T19:33:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-08Bitstream added on 2014-06-13T20:25:29Z : No. of bitstreams: 1 oliveira_ivm_dr_jabo.pdf: 1019049 bytes, checksum: 205fb28114ff3cf08f1d526343964c4e (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Esse trabalho teve por objetivo fornecer informações sobre aspectos morfológicos da semente; determinar a possibilidade de clonagem da variedade Duke 7 por alporquia; avaliar influência da época no pegamento da enxertia em abacateiro das variedades 'Hass' e 'Fortuna' e caracterizar, por estudos anatômicos e morfológicos, mudanças na gema vegetativa à florífera, para duas variedades de abacate 'Hass' e 'Fortuna'. As sementes são monoembriônicas e exalbuminosas, de germinação hipógea e a emergência das plântulas ocorreu 33 dias após a semeadura; a raiz primária é longa e de coloração branca e as raízes secundárias são curtas e filiformes; os cotilédones são maciços e de coloração rosada sendo que foi possível observar a presença de múltiplos caulículos na semente de abacate, originados do colo; os frutos são do tipo baga; as sementes apresentam policaulia; o início da estabilização da emergência de plântulas ocorre na oitava semana. Não houve enraizamento dos alporques; o período mais indicado para o sucesso da enxertia, é de modo geral, compreendido entre os meses de novembro e dezembro para ambas as variedades 'Hass' e 'Fortuna'. A transição entre a fase vegetativa e a reprodutiva ocorre no mês de maio, quando há diminuição da temperatura; a evocação floral ocorre um mês após, caracterizado pelo formato arredondado das gemas; a iniciação da inflorescência ocorre dois meses após a transição, no mês de julho.
This work aimed to study morphological aspects of seeds; determine the cloning possibility of Duke 7 cultivar by air layering; evaluate the influence of the season on grafting of Hass and Fortuna avocado cultivars and to characterize by anatomical and morphological studies the modifications on vegetative to flowering bud. The seeds are monoembryonic, the germination is hypogea and the emergence of seedlings occurred 33 days after planting; the main root is long, white and the secondary roots are short; the cotiledons are hard and pink; the seeds presented polystems it was observed the presence of many small stems on avocado seed; the fruit is a berry. The stabilization of seed emergency occurred with eight weeks. There was no rooting in the air-Iayerings; the season more indicated for grafting is between November and December for both cultivars. The change from vegetative to reproductive phase was in May, when there is lower temperatures; the floral evocation occurs one month after, characterized by the rounded format of buds; the initiation of the inflorescence occurs after two months of the transition, in July.

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Rezende, Karla Mayra Pinto e. Carvalho. "Células-tronco da polpa e papila apical dental humanas: análise morfológica, funcional e por microfluorescência de raios X." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/23/23132/tde-18032015-171529/.

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A proposta desse projeto de pesquisa foi analisar e caracterizar células-tronco encontradas na polpa dentária e papila apical de um mesmo doador tratadas sob as mesmas condições de cultivo utilizando abordagens que permitem analises de componentes intracelulares que nunca antes haviam sido analisados nessas células. Para tanto, populações enriquecidas pela expressão CD146, STRO-1 e CD90 foram isoladas de terceiros molares inclusos indicados para exodontia, totalizando 16 pacientes e 16 dentes. Como controles negativos, foram utilizadas as células negativas para esses marcadores. Células positivas e negativas para cada marcador foram comparadas entre si e com os resultados dos outros marcadores. Para cada um dos marcadores e respectivos controles foram realizadas analises de cinética celular, ensaios morfológicos e ensaios subcelulares utilizando microscopia de luz sincrotron. Os dados obtidos foram submetidos à teste ANOVA e teste de Tukey (a=0,05) quando pertinente e/ou a análises descritivas. As células isoladas da polpa dentária e papila apical se comportaram diferentemente uma das outras. Nos ensaios de cinética celular, as células enriquecidas (positivas) apresentaram crescimento mais lento quanto comparados com as células não enriquecidas (negativas), independente do marcador em questão. Nos ensaios morfológicos, células CD 90+ da polpa dentária exibiram a menor área e menor perímetro quando comparadas com as CD 146+ e STRO-1+. A presença de compostos iônicos vistos por luz sincrotron mostraram maior fração de massa nas células positivas da polpa dentária. Dentre os elementos traços estatisticamente mais prevalentes foram o fósforo, cobre, zinco, potássio, estrôncio, cálcio e cloro, sendo este último presente na polpa e papila nos 3 marcadores estudados. Concluímos que tanto da polpa dentária quanto na papila apical de dentes humanos, há presença de células tronco multipotentes expressados pelos três marcadores e que apesar de serem obtidos do mesmo dente e doador e cultivados de forma iguais ela tem comportamentos diferentes. As alterações bioquímicas celulares estudadas pelos elementos traços em células separadas por diferentes marcadores foi o primeiro passo para possibilitar os conhecimentos mecanicistas vitais celulares que não são observadas em microscopia padrão. Porém, novos estudos como permitir a visualização da localização espacial de biomarcadores espectrais caracterizados, pode ajudar a consolidar os resultados aqui encontrados. Assim, a análise e classificação desse método de estudo pode ser refinado em pesquisas futuras, incluindo no uso de outros tipos de tecidos dentais para caracterizar as células tronco dentais.
The purpose of this research project was to analyze and characterize stem cells found in dental pulp and apical papilla from the same donor treated under the same culture conditions using approaches that allow analysis of intracellular components that had never before been analyzed in these cells. Therefore, populations enriched for CD146 expression, STRO-1 and CD90 were isolated from third molars indicated for extraction, totaling 16 patients and 16 teeth. As negative controls, cells negative for these markers were used. Positive and negative cells for each marker were compared and the results of other markers. For each of the markers and their controls were carried out analysis of cell kinetics, morphological tests and subcellular assays using synchrotron light microscopy. The data were submitted to ANOVA and Tukey\'s test (a = 0.05) where relevant and / or descriptive analyzes. Cells isolated from the apical papilla and dental pulp behaved differently from each other. In cell kinetics assays, enriched cells (positive) showed slower growth as compared with non-enriched cells (negative), regardless of the marker in question. In morphological studies, CD 90+ cells in the dental pulp exhibited a smaller area and lower perimeter compared to CD 146+ and STRO-1 +. The presence of ionic compounds seen by synchrotron light showed higher mass fraction of positive cells in the dental pulp. Among the most prevalent statistical trace elements are phosphorous, copper, zinc, potassium, strontium, calcium and chlorine, the latter being present in the pulp, and the papilla 3 markers studied. We conclude that both the dental pulp as the apical papilla of human teeth, there is presence of multipotent stem cells expressed the three markers and that although they are obtained from the same tooth and donor and grown in the same way it has different behaviors. The biochemical cellular changes studied by trace elements in separate cells with different markers was the first step to allow mechanistic cellular vital knowledge that is not observed in standard microscopy. However, new studies as to visualize the spatial location characterized spectral biomarkers can help consolidate the present results. Thus, the analysis and classification of the study method can be refined in future research including the use of other types of dental tissues to characterize the dental stem cell.

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Sahin, Serkan. "Language Modeling For Turkish Continuous Speech Recognition." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/2/1223254/index.pdf.

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This study aims to build a new language model for Turkish continuous speech recognition. Turkish is very productive language in terms of word forms because of its agglutinative nature. For such languages like Turkish, the vocabulary size is far from being acceptable from only one simple stem, thousands of new words can be generated using inflectional and derivational suffixes. In this work, word are parsed into their stem and endings. First of all, we consider endings as words and we obtained bigram probabilities using stem and endings. Then, bigram probabilities are obtained using only the stems. Single pass recognition was performed by using bigram probabilities. As a second job, two pass recognition was performed. Firstly, previous bigram probabilities were used to create word lattices. Secondly, trigram probabilities were obtained from a larger text. Finally, one-best results were obtained by using word lattices and trigram probabilities. All work is done in Hidden Markov Model Toolkit (HTK) environment, except parsing and network transforming.

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McAllister, Donald P. "Shearing Mechanisms and Complex Particle Growth in Nickel Superalloy 718." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461079188.

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Ballester, Beltrán José. "Sandwich-like systems to engineer the cellular microenvironment." Doctoral thesis, Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/48166.

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Abstract While most of the in vitro cultures are carried out on bi-dimensional (2D) substrates, most of the in vivo extracellular matrices are threedimensional (3D). Consequently cells behave differently on 2D substrates as a way to self-adaptation to a non-physiological environment. This fact has encouraged the development of more relevant culture conditions seeking to provide more representative models for biomedicine (e.g. cancer, drug discovery and tissue engineering) and further insights into any dimension-dependent biological mechanism. Different 3D culture systems have been established though their variability and complexity hinder their standardisation in common cell culture procedures. So, this thesis deals with the dimensionality issue in cell/material interactions and introduces sandwich-like microenvironments as a versatile tool to study cell behaviour. Cells cultured within this system use both dorsal and ventral receptors to adhere and spread, undergoing important changes with respect to the 2D cultures and approaching to 3D conditions. Stimulation of dorsal receptors has been previously addressed by overlaying a protein gel on cells already attached on a 2D surface. Here we propose a sandwich-like system that consists of two 2D surfaces so that wider spectra of conditions can be investigated by changing the nature of the substrate (material, topography…) and the protein coatings of both ventral and dorsal sides. Since sandwich culture provides an altered cellular adhesion compared to the traditional 2D substrates by the excitation of the dorsal receptors, changes in the intracellular signalling are expected, which might alter important processes such as proliferation, morphology, migration and differentiation. Hence this thesis evaluates the effect of different sandwich culture parameters in cell behaviour. First, cell fate upon adhesion was evaluated in terms of morphology, proliferation and adhesion. Different conditions were studied such as materials with different properties or protein coatings (dorsal and ventral substrates), as well as the effect of sandwiching cells just after seeding or after been allowed to adhere to the ventral substrate. Interesting results were obtained such as the relationship between the ability of cells to reorganise the ECM with cell morphology, proliferation and adhesion, similarly as observed in 3D hydrogels (degradable vs nondegradable systems). Then, cell migration within sandwich culture was studied by live imaging of a wound healing assay. Results revealed the key effect of both ventral and dorsal substrates in determining the migration rate as well as the migration mode used by cells. Moreover cells within the sandwich culture migrating in the wound healing assay adopted an elongated cell morphology that resembled cells migrating in other 3D systems. Beyond differences in cell morphology and migration, dorsal stimulation promoted cell remodelling of the extra-cellular matrix (ECM) over simple ventral receptor activation in traditional 2D cultures. Finally the effect of sandwich culture on cell differentiation was evaluated. First we showed an increase in C2C12 myogenic differentiation when cultured within the sandwich system. This enhancement was shown to be dorsal stimulation dependent and related to an alteration of the signalling pathway and the growth factor release. To determine if sandwich culture leads only to myogenic differentiation or whether it allows differentiation to other lineages, 4 different human mesenchymal stem cells (hMSCs) lines were cultured under the same conditions. Results showed the same sandwich environment triggered different cell differentiation. This points out the importance of the microenvironment cell niche in vivo, which highly influence cell fate, and thus the need of mimicking it properly in vitro. Overall, sandwich-like microenvironments switch cell behaviour towards 3D-like patterns, demonstrating the importance of this versatile, simple and robust approach to mimic cell microenvironments in vivo.
Ballester Beltrán, J. (2014). Sandwich-like systems to engineer the cellular microenvironment [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48166
TESIS

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Soares, Manuela Gonoring. "Plasticidade fenotípica de plantas jovens de Handroanthus chrysotrichus (Mart. Ex DC.) Mattos (Bignoniaceae) em resposta a radiação solar." Universidade Federal do Espírito Santo, 2012. http://repositorio.ufes.br/handle/10/5728.

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Made available in DSpace on 2016-12-23T13:48:26Z (GMT). No. of bitstreams: 1 Manuela Gonoring Soares - texto.pdf: 1466930 bytes, checksum: 1d3ed3b45ce030e2a560ba080600448e (MD5) Previous issue date: 2012-02-28
A capacidade das plantas em apresentar respostas adaptativas funcionais em relação às condições ambientais é conhecida como plasticidade, podendo ser expressa pelo processo de aclimatação. No ambiente florestal, a luz é um dos fatores principais no estabelecimento e distribuição de espécies vegetais. Neste contexto, espécies mais plásticas apresentam maiores taxas de sobrevivência em relação à variação da disponibilidade luminosa. Os ajustes podem ser fisiológicos, morfológicos e anatômicos e variam de acordo com o nível de exposição à radiação e as características de plasticidade do indivíduo. Dessa forma, o presente estudo teve como objetivo avaliar a plasticidade de plantas jovens de Handranthus chrysotrichus em resposta a diferentes intensidades luminosas. Para tanto, as plantas foram submetidas a três tratamentos: pleno sol (100% de radiação), sombreamento moderado (50% de radiação solar) e sombreamento severo (5% de radiação solar). A plasticidade foi avaliada por meio da análise de modificações de características aos níveis fisiológicos, morfológicos e anatômicos. Foram realizadas análises de crescimento, teor de pigmentos fotossintetizantes, teor de carboidratos solúveis foliares, atividade de enzimas antioxidantes (catalase e peroxidase do ascorbato), anatomia foliar (espessura da cutícula, da epiderme, parênquima paliçádico, mesofilo paravenal, parênquima esponjoso e densidade estomática) e caulinar (espessura da periderme, floema secundário, faixa cambial, xilema secundário e diâmetro, comprimento e densidade dos vasos), testes histoquímicos e índice de plasticidade (IP), após 90 e 200 dias de tratamento. Para as folhas, foram realizadas avaliações em folhas pré-existentes à submissão aos tratamentos e em folhas novas emitidas. As plantas apresentaram respostas comumente encontradas em espécies adaptadas ao sol e à sombra. O crescimento foi estimulado em resposta à alta irradiância, pelo maior acúmulo de massa seca e carboidratos solúveis foliares. O teor de pigmentos fotossintetizantes foi superior nas plantas sob sombreamento severo. A atividade da enzima catalase foi inferior nas plantas submetidas ao pleno sol e a enzima peroxidase do ascorbato não apresentou variação entre os tratamentos ao final do experimento. Em relação à anatomia foliar, houve variações na espessura da cutícula, dos tecidos foliares e na densidade estomática. O caule apresentou variações quanto à espessura dos tecidos avaliados, diâmetro e densidade dos vasos. As variáveis anatômicas analisadas mostraram valores superiores nas plantas em pleno sol e sombreamento moderado. Em relação aos testes histoquímicos, foram encontradas diferenças na deposição de grãos de amido em tecidos caulinares, maior em pleno sol. A análise do IP demonstrou que os ajustes após 90 dias de tratamento foram predominantemente fisiológicos, sendo o teor de pigmentos fotossintetizantes e a massa seca total, as características mais plásticas. Entretanto, ao final de 200 dias de tratamento, os ajustes foram predominantemente morfológicos (massa foliar específica, área foliar específica, razão de área foliar, bem como a produção de massa seca total), anatômicos foliares (espessura do parênquima esponjoso, densidade estomática) e anatômicos caulinares (espessura da faixa cambial). Os resultados obtidos indicam que plantas jovens de H. chrysotrichus apresentam grande plasticidade frente à variação da disponibilidade de luz, o que torna essa espécie recomendada para projetos de reflorestamento e recuperação de áreas degradadas
The ability of plants to show functional adaptive responses in relation to environmental conditions is known as plasticity and can be expressed by the acclimation process. In the forest environment, light is a major factor in the establishment and distribution of plant species. In this context, more plastic species have higher survival rates in relation to the variation of light availability. Adjustments can be physiological, morphological and anatomical and vary with the level of radiation exposure and the characteristics of plasticity of the individual. Thus, this study aimed to evaluate the plasticity of young plants of Handranthus chrysotrichus in response to different light intensities. For this purpose, plants were subjected to three treatments: full sun (100% of solar radiation), moderate shade (50% of solar radiation) and severe shading (5% of solar radiation). The plasticity was evaluated by analyzing changes in physiological characteristics levels, morphological and anatomical. Analyses of growth, photosynthetic pigments content, leaf soluble carbohydrates, antioxidant enzymes (catalase and ascorbate peroxidase), leaf anatomy (thick cuticle, epidermis, palisade parenchyma, paravenal mesophyll, spongy mesophyll and stomatal density) and stem anatomy (thickness of the periderm, secondary phloem, vascular cambium, secondary xylem, diameter, length and density of vessels), histochemical tests and plasticity index (PI) after 90 and 200 days of treatment. For leaves, were evaluated leaves pre-existing to the treatments and new leaves that emerged. Plants show responses commonly found in species adapted to sun and shade. Growth was stimulated in response to high irradiance by the greater accumulation of dry weight and leaf soluble carbohydrates. The content of photosynthetic pigments was higher in plants under severe shading. The catalase activity was lower in plants grown under full sun and the enzyme ascorbate peroxidase did not vary between treatments at the end of the experiment. In relation to leaf anatomy, there were variations in the thickness of the cuticle, of measured leaves tissues and stomatal density. The stem showed variation in the measured tissue thickness, diameter and density of vessels. The anatomic variables analyzed showed higher values in plants in full sun and moderate shade. Regarding the histochemical tests, differences were found in the deposition of starch grains in stem tissues, most in full sun. The analysis of IP demonstrated that the adjustments after 90 days of treatment were predominantly physiological. The content of photosynthetic pigments and the total dry mass were the most plastic characteristics. However, after 200 days of treatment, the settings were predominantly morphological (specific leaf mass, specific leaf area, leaf area ratio, as well as the production of total dry mass), leaf anatomical (thickness of the spongy parenchyma, stomatal density) and anatomical stem (thickness range of vascular cambia). The results indicate that young plants of H. chrysotrichus exhibit great plasticity to the variation of light availability, which makes this recommended species for reforestation and reclamation

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Voß, Manja. "Revision of the Halitherium-species complex (Mammalia, Sirenia) from the late Eocene to early Miocene of Central Europe and North America." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16906.

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Die zu den Sirenia, oder Seekühen, zählende Gattung Halitherium ist mit Arten aus dem Obereozän bis Untermiozän bekannt. Obwohl Halitherium als monophyletisch angesehen wird, bestätigen alle bisherigen phylogenetischen Analysen die Paraphylie dieser Gruppe. Auch die auf Halitherium basierende nur fossil bekannte Unterfamilie Halitheriinae ist paraphyletisch und umfasst wiederum fast ausnahmslos paraphyletische Gattungen. Der Fokus liegt auf der Typusart H. schinzii. Deren Holotyp, ein Premolar, wird als undiagnostisch definiert und infolgedessen H. schinzii als nomen dubium eingestuft. Die Neubeschreibung sämtlicher dieser Art zugeordneter Skelettreste liefert neue morphologische Daten. So kann die Hypothese von zwei sympatrisch vorkommenden Morphospezies im Unteroligozän Zentraleuropas auf Basis mehrerer unterscheidender Merkmale gestützt werden. Für die Verwandtschaftsanalyse der „Halitherium“ traditionell zugeordneten Arten und die Ermittlung ihrer phylogenetischen Stellung innerhalb der Ordnung Sirenia finden strenge kladistische Prinzipien Berücksichtigung. Eine revidierte, ergänzte und erweiterte Merkmalsmatrix stellt dabei den bisher größten morphologischen Datensatz über Sirenia dar. Die phylogenetischen Analysen zeigen, dass die „Halitherium“ Arten keine monophyletische Gruppe bilden. Im Zuge dieser systematisch-taxonomischen Revision werden die „Halitheriinae“ eingezogen und vier neue Gattungen aufgestellt. Des Weiteren wird eine neue Klassifikation der Sirenia vorgeschlagen, in der eine konsequente Unterscheidung zwischen einer paraphyletischen Stammgruppe und einer monophyletischen Kronengruppe Anwendung findet. Diese Studie liefert neue Daten über die Diversität und Biogeographie von Sirenen. Die herausragendsten Ergebnisse sind zum einen die Revision einer der zweifelhaftesten Sirenia Gruppen, die „Halitheriinae“. Zum anderen wird für den Ursprung der Kronengruppensirenen ein eher unteroligozäner statt eozäner Zeitpunkt postuliert.
The genus Halitherium includes a number of fossil sirenian species, or sea cows, ranging from the late Eocene to early Miocene. Although Halitherium is assumed to be monophyletic, all previous phylogenetic analyses reveal this group to be paraphyletic. As such, the exclusively extinct subfamily Halitheriinae based on Halitherium is paraphyletic comprising mainly genera that are invariably paraphyletic as well. The focus lies on the type species H. schinzii and the morphological basis for its establishment. The holotype, a single premolar, is considered non-diagnostic, which resulted in the recognition of this taxon name as a nomen dubium. Abundant skeletal material originally assigned to “H. schinzii” is re-described providing new data on the morphology of this sirenian. In this process, the hypothesis of two sympatric morphospecies in the lower Oligocene of Central Europe is corroborated by a suite of distinguishing characters. For the analysis of the interrelationships of the species traditionally assigned to “Halitherium”, and the identification of their phylogenetic position within the order Sirenia, robust cladistic principles are applied. A revised, supplemented and extended data matrix represents the hitherto largest data set on Sirenia based on morphological characters. The phylogenetic analyses show that the “Halitherium” species do not form a monophyletic group. In the course of this systematic and taxonomic revision the “Halitheriinae” are refuted and four new genera are established. Furthermore, a new systematic framework is introduced for Sirenia primarily distinguishing between a paraphyletic stem group and a monophyletic crown group. This study provides new data on the past sirenian diversity and biogeography. The most important results are that one of the most disputed sirenian groups, the “Halitheriinae”, is revised, and that the divergence time of crown group sirenians is estimated as early Oligocene rather than Eocene.

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Rosenberg, Maria. "La formation agentive en français : les composés [VN/A/Adv/P]_N/A et les dérivés V-ant, V-eur et V-oir(e)." Phd thesis, Stockholms universitet, Institutionen för franska, italienska och klassiska språk, 2008. http://tel.archives-ouvertes.fr/tel-00486981.

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This study addresses the French morphological construction [VN/A/Adv/P]N/A. The main objectives are to posit a single rule for its formation and to question the implications of the agent polysemy. The theoretical framework is lexeme-based morphology, which adheres to weak lexicalism. The first part of our analysis is qualitative and concerns the availability aspect of productivity. The method is introspective. The internal semantic patterns of the French construction are examined. Our results give evidence for the claim that a single morphological construction rule, [VN/A/Adv/P]N/A, is responsible for the cases where the first constituent is a verb stem, and the second constituent may correspond to an internal argument, an external argument or a semantic adjunct. All cases manifest the same patterns, which are related to the denotative meanings included in the agent polysemy: Agent, Instrument, Locative, Action, Result and Cause. Our contrastive analysis shows that the same patterns are found in the four Swedish agentive formations, [N/A/Adv/PV-are]N, [N/A/Adv/PV]N, [N/A/Adv/PV-a]N and [VN]N, which correspond to the French [VN/A/Adv/P]N/A construction and which also contain a verbal constituent and its internal or external argument, or an adjunct. The second part of our analysis is quantitative and concerns the profitability aspect of productivity. The method is inductive. The aim is to explore the polysemy of agent and its assumed hierarchical structure, in synchrony and diachrony. Four French agentive formations, [VN/A/Adv/P]N/A compounds and V-ant, V-eur and V-oir(e) derivations, are included in order to examine semantic competition and blocking effects. Our results give evidence for the existence of an agent polysemy but deny that it has a hierarchical structure valid for every agentive formation. The meanings in the agent polysemy are more or less profitable according to formation type: blocking effects could explain this behaviour.

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Milzow, Christian. "The step-pool morphology of a steep mountain stream /." ETH, Eidgenössische Technische Hochschule Zürich, Institut für Hydrologie und Wasserwirtschaft, 2004. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=137.

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Stewart, Thomas W. Jr. "Mutation as morphology: bases, stems, and shapes in Scottish Gaelic." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1086046888.

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Stewart, Thomas W. "Mutation as morphology bases, stems, and shapes in Scottish Gaelic /." Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5num=osu1086046888.

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Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains ix, 183 p. : ill. Advisor: Brian D. Joseph, Department of Linguistics. Includes bibliographical references (p. 173-183).

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Garcia-Jaldon, Catherine. "Caractérisation morphologique et chimique du chanvre (Cannabis sativa) : prétraitement à la vapeur et valorisation." Grenoble 1, 1995. http://www.theses.fr/1995GRE10140.

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La tige de chanvre est composee de deux regions de morphologie distincte: le cortex qui contient des fibres riches en pectines et en hemicelluloses et le bois qui est un tissu fortement lignifie constitue de vaisseaux, de fibres de bois et cellules de parenchyme ligneux. Une etude des pectines de chanvre a montre que ces polysaccharides sont constitues d'une chaine principale rhamnogalacturonane au sein de laquelle alternent des zones d'acide galacturonique (regions lisses) et des zones ramifiees (regions chevelues). Dans ces regions chevelues, a peu pres la moitie des unites rhamnose portent en position o-4 une courte chaine laterale compose principalement d'unites galactose et arabinose. D'autre part dans l'optique d'une valorisation des fibres contenues dans la tige de chanvre (fibres corticales et fibres du bois), nous avons etudie l'influence des parametres de traitement a la vapeur sur la purification et l'individualisation de ces fibres. Les fibres ainsi obtenues ont ete par la suite incorporees dans une matrice polypropylene et il ressort de cette etude que les fibres de chanvre peuvent ameliorer les proprietes mecaniques du materiau final a condition qu'il y ait une bonne adhesion entre fibre et matrice

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Jones, Aleksy K. "Kinetically determined surface morphology in epitaxial growth." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2499.

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Molecular beam epitaxy has recently been applied to the growth and self assembly of nanostructures on crystal substrates. This highlights the importance of understanding how microscopic rules of atomic motion and assembly lead to macroscopic surface shapes. In this thesis, we present results from two computational studies of these mechanisms. We identify a kinetic mechanism responsible for the emergence of low-angle facets in recent epitaxial regrowth experiments on patterned surfaces. Kinetic Monte Carlo simulations of vicinal surfaces show that the preferred slope of the facets matches the threshold slope for the transition between step flow and growth by island nucleation. At this crossover slope, the surface step density is minimized and the adatom density is maximized, respectively. A model is developed that predicts the temperature dependence of the crossover slope and hence the facet slope. We also examine the "step bunching" instability thought to be present in step flow growth on surfaces with a downhill diffusion bias. One mechanism thought to produce the necessary bias is the inverse Ehrlich Schwoebel (ES) barrier. Using continuum, stochastic, and hybrid models of one dimensional step flow, we show that an inverse ES barrier to adatom migration is an insufficient condition to destabilize a surface against step bunching.

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Zhang, Musan. "Advancing Step-Growth Polymers: Novel Macromolecular Design and Electrostatic Interactions in Polyesters and Polyurethanes." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23239.

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Conventional melt transesterification successfully synthesized high molecular weight segmented copolyesters. The cycloaliphatic monomers 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) and dimethyl-1,4-cyclohexane dicarboxylate (DMCD) afforded sterically hindered, ester carbonyls in high-Tg polyester precursors. Reaction between the polyester polyol precursor and a primary or secondary alcohol at melt polymerization temperatures revealed reduced transesterification of the polyester hard segment as a result of enhanced steric hindrance adjacent to the ester linkages. Subsequent polymerization of a 4,000 g/mol polyol with monomers comprising the low-Tg block yielded high molecular weight polymers that exhibited enhanced mechanical properties compared to a non-segmented copolyester control. Atomic force microscopy uncovered unique needle-like, interconnected, microphase separated surface morphologies, and small-angle X-ray scattering confirmed the presence of bulk microphase separation. This new synthetic strategy enabled selective control of ionic charge placement into the hard segment or soft segment block of segmented copolyesters using melt transesterification. The ionic placement impacted the microphase-separated morphology, which influenced its thermomechanical properties and resulting mechanical performance. Melt transesterification of low-Tg, sodium sulfonated copolyesters achieved up to 15 mol% ionic content. The 10 and 15 mol% sodium sulfonated copolyesters exhibited water-dispersibility, which enabled cation dialysis exchanges to divalent metal cations. The sulfonated copolyesters containing divalent metal cations exhibited enhanced rubbery plateau moduli to higher temperatures. Novel trialkylphosphonium ionic liquids chain extenders enabled the successful synthesis of poly(ethylene glycol)-based, cationic polyurethanes with pendant phosphoniums in the hard segments (HS). Aqueous size exclusion chromatography (SEC) confirmed the charged polyurethanes, which varied the phosphonium alkyl substituent length (ethyl and butyl) and cationic HS content (25, 50, 75 mol%), achieved high absolute molecular weights. Dynamic mechanical analysis (DMA) demonstrated the triethylphosphonium (TEP) and tributylphosphonium (TBP) polyurethanes displayed similar thermomechanical properties, including increased rubbery plateau moduli and flow temperatures. Fourier transform infrared spectroscopy (FTIR) emphasized the significance of ion-dipole interaction on hydrogen bonding. Atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and wide-angle X-ray diffraction (WAXD) supported microphase separated morphologies in the trialkylphosphonium polyurethanes, despite the presence of ionic interactions. Sorption isotherm experiments revealed TBP polyurethanes displayed similar water sorption profiles to the noncharged analogue and lower water absorptivity compared to TEP. The phosphonium polyurethanes displayed significantly improved tensile strain; however, lower tensile stress of the TEP polyurethane was presumably due to absorbed water. In addition, we also explored applications of the trialkylphosphonium polyurethanes as nucleic acid delivery vectors and demonstrated their abilities to form colloidally stable polyplexes in salt-containing media.
Ph. D.

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Pang, Angbo. "Mass transport during step motion on the Si(111) (1x1) surface studied by low energy electron microscopy /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202009%20PANG.

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Vissotto, Fernanda Zaratini. "Estudo do processo de aglomeração com vapor e perda de qualidade por caking de achocolatados em pó." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256468.

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Orientadores: Florencia Cecilia Menegalli, Maria Isabel Rodrigues
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Os achocolatados em pó são formulados com a mistura de cacau, açúcar, maltodextrina e aromas, podendo conter derivados lácteos. Para se obter uma adequada reconstituição em líquidos, os achocolatados são submetidos aos processos de lecitinação (adição de um agente tensoativo: lecitina de soja) e aglomeração com vapor. Um dos objetivos desse estudo foi o de avaliar os efeitos das variáveis do processo de aglomeração com vapor (pressão do vapor, temperatura do secador rotativo, vazão de sólidos da alimentação e frequência de rotação do secador) sobre as características físicas e físico-químicas de achocolatados em pó. A aglomeração com vapor levou a um aumento do diâmetro médio de partículas, sendo mais pronunciado no produto formulado com o açúcar moído. O processo foi responsável pelo escurecimento e redução da umidade dos achocolatados, além da diminuição dos tempos de molhabilidade. Adicionalmente foi caracterizada a morfologia dos grânulos de achocolatado, obtidos em diferentes condições operacionais do aglomerador (máxima, média e mínima), utilizando os descritores de tamanho e forma. Os resultados mostraram que não existe diferença entre os descritores de forma e quanto aos descritores de tamanho verificou-se diferença entre as condições de processo para grânulos maiores que 600 ?m. Concluiu-se que os grânulos de achocolatado aglomerados apresentaram formato alongado. Foram também determinadas as transições de fase e as temperaturas de transição vítrea (Tg) de achocolatados em pó e dos seus principais constituintes. Durante a aglomeração com vapor a alta temperatura levou o açúcar moído a uma condição acima da sua Tg, passando a ser esse componente um veículo para a granulação. A Tg da maltodextrina é pequena em atividades de água elevadas (Tg= - 4,9 °C; Aa= 0,843), o que também a torna um veículo para o processo de aglomeração. No cacau em pó alcalino foi observada a fusão da manteiga de cacau (aparecimento das formas polimórficas ?v e ?). Para o achocolatado lecitinado verificou-se que a Tg aumenta com o incremento da atividade de água do meio, portanto para esse tipo de produto a água, ao ser adsorvida, não consegue interagir com o material, não sendo verificado o efeito plasticizante. Para o achocolatado aglomerado com vapor verificou-se que a Tg diminuiu com o aumento da atividade de água do meio (efeito plasticizante). A evolução do caking dos constituintes dos achocolatados mostrou que o cacau em pó apresentou baixa higroscopicidade (pequeno aumento do ângulo de repouso com o tempo), pequena formação de aglomerados e a ausência do caking. A medida da força de compressão dos agregados formados mostrou que a sacarose formou pontes mais rígidas entre as partículas que a maltodextrina. Foi também monitorada a estabilidade de achocolatados em pó lecitinados e aglomerados com vapor, estocados a 25 e 35 °C, numa umidade relativa de 84%, buscando-se simular um clima quente e úmido (região norte do Brasil). Ao longo do tempo, verificou-se aumento do ângulo de repouso e escurecimento dos produtos. O achocolatado lecitinado mostrou-se mais susceptível ao empedramento que o aglomerado, com a formação de grumos a partir do 63° dia de armazenamento
Abstract: Cocoa beverage powders consist of a mixture of cocoa, sugar, maltodextrin, flavors, and may contain dairy products. To obtain products with adequate reconstitution in liquids, the cocoa beverage powders are subjected to the processes of lecithination (addition of the surfactant soy lecithin) and steam agglomeration. One objective of this study was to evaluate the effects of the main variables of the steam agglomeration process (vapor pressure, temperature of rotary dryer, solid feed rate and dryer rotation frequency) on the physical and physicochemical characteristics of cocoa beverage powders. The steam agglomeration led to an increased average particle diameter, being more pronounced in the product formulated with granulated sugar. The process was responsible for powder darkening, reduction of the product¿s moisture and decrease in the wettability. Additionally, the morphology of the cocoa beverage powder granules was characterized in different operating conditions of the steam agglomerator (maximum, average and minimum) using the descriptors of size and shape. There were no differences between the shape descriptors and as to the size descriptors there were differences in the process conditions studied for the granules of size above 600 ?m. It was observed that the steam agglomerated cocoa beverage granules had a more elongated shape. It was also determined phase transitions and the glass transition temperature (Tg) of cocoa beverage powders and the main constituents of these products. During the steam agglomeration, the high temperature led the granulate sugar to a condition above its Tg, making this ingredient a granulation vehicle. The Tg of maltodextrin is small at higher water activities (Tg = - 4.9 °C, aw = 0.843), which makes this ingredient a vehicle for the agglomeration process. For the alkaline cocoa powder the phase transition observed is the melting of the cocoa butter with the appearance of polymorphic forms ? and ?v. For the lecithinated cocoa beverage powder, it was verified that the Tg increases with the increasing of the water activity, which leads to the conclusion that for this type of product the adsorbed water cannot interact with the material, and the plasticizing effect is not noted. For the steam agglomerated cocoa beverage powder it was observed that the Tg decreases with increasing water activity (plasticizing effect). The evolution of the caking for the constituents of cocoa beverage powders showed that the cocoa powder had low hygroscopicity (small increase of the repose angle with time), little formation of granules and the absence of caking. The measurement of the compression strength of the aggregates showed that sucrose formed bridges more rigid between the particles than maltodextrin. Stability of lecithinated and steam agglomerated cocoa beverage powders stored at 25 and 35 °C, in a relative humidity of 84%,was also monitored, in order to simulate hot and humid climates (like northern Brazil). Overtime, it was observed increase of the repose angles and products darkening. The lecithinated cocoa beverage powder was more susceptible to caking than the steam agglomerated product, with the formation of lumps from the 63th day of storage
Doutorado
Engenharia de Alimentos
Doutora em Engenharia de Alimentos

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32

Ter, Veer Mirelle Jamilla Tamara. "Nanoscale imaging of synapse morphology in the mouse neocortex in vivo by two-photon STED microscopy." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0217/document.

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Le cerveau est un organe complexe composé de neurones et des cellules non-neuronales. La communication entre les neurones a lieu via les synapses, dont le remodelage morphologique est considéré essentiel pour le traitement et le stockage des informations dans le cerveau des mammifères. Récemment, ce point de vue neuro-centré de la fonction synaptique a évolué, en prenant également en compte les processus gliaux à proximité immédiate de la synapse. Cependant, comme leur structure est bien en deçà de la résolution spatiale de la microscopie optique conventionnelle, les progrès dans les enquêtes dans leur environnement physiologique, le cerveau intact, ont été entravés. En effet, on sait peu sur les variations nanométriques de la morphologie des épines dendritiques et l'interaction avec les processus gliaux, et, finalement, comment elles affectent la transmission synaptique in vivo. Dans cette thèse, nous cherchons à visualiser la dynamique de la nano-morphologie des épines dendritiques et les processus gliaux dans le cortex à tonneaux de souris in vivo. Nous avons donc mis en place l’imagerie super-résolution 2P-STED en temps réel, ce qui permet une haute résolution spatiale et la pénétration profonde des tissus, chez la souris anesthésiée in vivo. Nous montrons que la nano-morphologie des épines est diversifiée, variable, mais globalement stable, et que les différences dans la morphologie des épines peut avoir un effet sur leur compartimentation in vivo. En outre, la mise en œuvre de l’imagerie super-résolution en double couleur in vivo et le développement d'une approche de marquage astrocytaire, nous ont permis de fournir la caractérisation à l'échelle nanométrique des interactions neurone-glie. Ces résultats apportent un aperçu sans précédent dans la dynamique de la synapse à l'échelle nanométrique in vivo, et ouvrent la voie à une meilleure compréhension de la façon dont les réarrangements morphologiques des synapses contribuent à la physiologie du cerveau
The brain is a complex organ consisting of neurons and non-neuronal cells. Communication between neurons takes place via synapses, whose morphological remodeling is thought to be crucial for information processing and storage in the mammalian brain. Recently, this neuro-centric view of synaptic function has evolved, also taking into account the glial processes in close vicinity of the synapse. However, as their structure is well below the spatial resolution of conventional light microscopy, progress in investigating them in a physiological environment, the intact brain, has been impeded. Indeed, little is known on the nanoscale morphological variations of dendritic spines, the interaction with glial processes, and how these affect synaptic transmission in vivo. Here, we aim to visualize the dynamic nano-morphology of dendritic spines in mouse somatosensory cortex in vivo. We implemented super-resolution 2P-STED time-lapse imaging, which allows for high spatial resolution and deep tissue penetration, in anesthetized mice, and show that the nano-morphology of spines is diverse, variable, but on average stable, and that differences in spine morphology can have an effect on spine biochemical compartmentalization in vivo. Moreover, implementation of dual color in vivo super-resolution imaging and a novel astrocytic labeling approach provided the first steps towards nanoscale characterization of neuron-glia interactions in vivo. These findings bring new insights in synapse dynamics at the nanoscale in vivo, and our methodological endeavors help pave the way for a better understanding of how nanoscale aspects of spine morphology and their dynamics might contribute to brain physiology and animal behavior

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33

Kha, Stephanie Tieu. "An Investigation of Cellular Proliferation and Nuclear Morphology in the Multi-Step Progression of Cutaneous Squamous Cell Carcinoma." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/579258.

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With 3.5 million cases diagnosed in more than 2 million people in the United States annually, skin cancer leads as a frequent and devastating disease carrying a large public health burden. Understanding the multi-step disease progression is crucial for developing interventional strategies that can reduce the incidence as well as the risk of recurrence for non-melanoma skin cancers. In this study of 40 tissue samples, cellular proliferation is quantified and analyzed in four categories that represent the stages of progression for SCC carcinogenesis: Normal, Sun-exposed, Actinic Keratosis, and Squamous Cell Carcinoma. The results in this study show an exponential increase in levels of Proliferative Cell Nuclear Antigen (PCNA) expression with each progressed category, as well as a positive association with nuclear morphology feature values related to sun-damaged nuclei that were published in a previous study. These findings support the utility of investigative techniques from the field of immunohistochemistry in studying the UV-induced skin carcinogenesis model for the multi-step disease progression of cutaneous squamous cell carcinoma. Furthermore, this study elucidates the complexities involved in clinical histological diagnoses for non-melanoma skin cancers.

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Pakiru, Swapna. "Effect of Step Change in Growth Speed During Directional Solidification on Array Morphology of Al-7 wt% Si Alloy." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1323970093.

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Linnemann, J., J. Giorgio, K. Wagner, G. Mathieson, G. G. Wallace, and D. L. Officer. "A simple one step process for enhancement of titanium foil dye sensitised solar cell anodes." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36240.

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The photo-conversion efficiency and stability of back-illuminated dye sensitised solar cells with titanium foil based photoanodes are enhanced by a simple nitric acid treatment through which the foil is passivated. This treatment changes the morphology of the titanium foil and increases its electrochemical double layer capacitance.

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Rizo, Steven R. "Quantifying the Effect of Topographic Slope on Lava Flow Thickness: A First Step to Improve Lava Flow Volume Estimation Methods." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7222.

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The volume of lava flows provide important information on the magnitude of volcanic eruptions, and accurate volumes are necessary to produce reliable models of lava flow emplacement or constrain the internal structure of volcanoes. The most accurate lava flow volumes are obtainable when the topography before and after an eruption are both known, but information for the topography before lava flow emplacement is absent in non-historic lava flows. To calculate the volume of non-historic lava flows, this pre-emplacement topography needs to be reconstructed. Common methods for this include using inverse distance-weighted averages or global polynomial interpolation methods, but these can still underestimate the volume of the flow, and the surface of the flow itself is not considered in these interpolations. A new calculation method seems necessary to better constrain the volume of lava flows, and including the lava flow surface in the volume calculation, given that it is generally excluded during interpolation of pre-emplacement topography, may be the solution to improving lava flow volume calculation for flows where the base surface is unknown. The 2012-2013 Tolbachik lava flow is used to look at potential relationships due to the availability of elevation data before and after the eruption. A quantitative analysis on the relationships between the slope of topography before and after lava flow emplacement and on the relationship between the slope and thickness of lava flows is performed. In addition to this, the slope of the topography calculated over local and regional scales is used as a new interpolation method, and the calculated thickness from the interpolated surface is compared to the known thickness for the lava flow.

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Jindra, Sarah A. "Hydrothermal Atomic Force Microscopy Investigation of Barite Growth: The Role of Spectator Ions in Elementary Step Edge Growth Kinetics and Hillock Morphology." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1503503972572962.

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Lantiat, David. "Morphologie et auto-organisation de nanoparticules métalliques dispersées dans des matrices diélectriques : influence sur les propriétés optiques." Phd thesis, Université de Poitiers, 2008. http://tel.archives-ouvertes.fr/tel-00331903.

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L'objectif de ce travail est d'ajuster la position spectrale de la résonance plasmon de surface de nanoparticules de métaux nobles dispersées dans une matrice diélectrique en contrôlant leur morphologie et leur organisation spatiale. Nous montrons que lorsque la croissance est réalisée sur des substrats plans, il est possible de jouer sur la nature de la matrice pour modifier le rapport d'aspect hauteur sur diamètre H/D des particules, et donc leur réponse optique. Des analyses structurales quantitatives menées par microscopie électronique en transmission à balayage (HAADF-STEM) font apparaître que H/D est une fonction décroissante du diamètre D, indépendamment de la quantité de métal déposé. Afin de comprendre ces effets de la matrice sur les propriétés structurales et optiques des particules, différentes études (influence du métal et de la quantité déposés, présence d'une couche tampon, influence des conditions d'élaboration, vitesse de recouvrement des particules, ... ) sont menées et des simulations numériques des spectres du facteur de transmission sont réalisées en intégrant dans un modèle de Yamaguchi les paramètres structuraux issus de l'analyse HAADF. Une autre approche consiste à utiliser des surfaces d'alumine nanostructurées afin d'induire une organisation surfacique des particules et ainsi entraîner une anisotropie de leurs propriétés optiques. Nous montrons que selon la géométrie de dépôt utilisée (incidence normale, incidence rasante, orientation et angle d'incidence du flux atomique), il est possible par effet d'ombrage de sélectionner le type de facettes sur lesquelles la croissance a lieu, et par conséquent d'organiser les nanoparticules d'argent sur la surface sous forme de bandes ou de chaînes linéaires, dont les propriétés optiques présentent une dépendance à la polarisation de la lumière incidente.

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Nielsen, Jon F. "Energetically and Kinetically Driven Step Formation and Evolution on Silicon Surfaces." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu998579834.

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Hu, Chen. "Surface Optimization of the Silicon Templates for Monolithic Photonics Integration." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37226.

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Silicon photonics is emerging as a potential field to achieve optical interconnects towards the realization of ultra high bandwidth. The indirect band-gap property of silicon still remains as a big challenge to incorporate silicon photonic active device, for example, silicon-based laser. In the Laboratory of Semiconductor Materials at KTH, a monolithic integration platform based on nano-epitaxial lateral overgrowth (nano-ELOG) technique has been proposed to integrate III-V semiconductor materials with silicon for light source application. The integration process involves uneven surface morphology at different stages. The surfaces of the indium phosphide seed layer on silicon used for ELOG, the mask deposited on it (the silicon/silicon dioxide waveguide) and the ELOG indium phosphide layer grown on it prior to laser growth are often rough. In this thesis work, we have optimized chemical mechanical polishing (CMP) technique in order to achieve an even surface. The same procedure is also necessary to reach the optimal thickness of different layers to enable effective coupling of light from the laser source into the waveguide. CMP of indium phosphide to obtain an average surface roughness of < 1 nm has been optimized by a two-step polishing using different slurries; it results in a step height of ca 3 nm. Similarly the surface of silicon/silicon dioxide “waveguide” has also been optimized with the roughness of ~ 0.5 nm. In the latter case, a step height of 40 nm is retained and this increase with respect to InP is identified to be mainly due to limitations of the polishing machine which is different from that used for indium phosphide. The reduction in step heights with polishing time is analyzed and compared with an existing theoretical model. Our results are in good qualitative agreement with the model. The optimized surface morphology obtained in this work was tested for its suitability for integration. For this evaluation, InP was grown by ELOG in a hydride vapour phase epitaxy reactor with and without CMP of the involved surfaces. The surface after CMP yields layers of better surface morphology with fewer defects as revealed by atomic force microscopy, surface profilometer and cathodoluminescence analysis. The results indicate that the CMP process is useful for monolithic integration for silicon photonics.

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Dion, Kenneth Michael. "Channel morphology and the distribution of juvenile Atlantic salmon habitat in the Ste. Marguerite River following the historic Saguenay flood of July 1996." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0006/MQ44157.pdf.

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Lange, Heinz [Verfasser]. "Ingredients, Morphology and Color Changes of Herbal Drugs and Spices after Mechanical Saturated Steam Decontamination / Heinz Lange. Julius Kühn-Institut. Technische Universität Carolo-Wilhelmina zu Braunschweig." Quedlinburg : Julius Kühn-Institut, 2013. http://d-nb.info/1105566595/34.

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43

Le, Goff Eric. "Morphologie de surfaces vicinales de métaux purs et d'alliages : stabilité et rugosité. Expériences et modélisations." Phd thesis, Université Paris Sud - Paris XI, 1999. http://tel.archives-ouvertes.fr/tel-00004237.

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Pour les applications technologiques impliquant des propriétés de surface, il est nécessaire de comprendre et de maîtriser les phénomènes de rugosité et d'instabilité de surface des cristaux de métaux purs et d'alliages. Dans ce but, trois surfaces ont été étudiées expérimentalement : Cu(1,1,5), Cu83Pd17(1,1,5) et Cu3Au(1,1,11). La face Cu(1,1,5) a été étudiée par STM (Scanning Tunneling Microscopy) à température variable entre 300 K et 365 K. Nous avons observé, dans toute la gamme de température explorée, que cette surface est stable et non rugueuse. La comparaison des résultats expérimentaux avec des simulations Monte Carlo a permis de déterminer la constante d'interaction entre marches A=100 K (interaction élastique entre marches en A/L^2) et l'énergie de formation de crans en bord de marches Ek=1430 K. La détermination de la température de transition rugueuse du Cu(1,1,5) nous a conduit à étendre ce résultat en calculant le diagramme de phases des faces vicinales dans l'espace des paramètres (A, Ek et angle de coupe). Ce diagramme de phases complet (A>0, A<0) d'un système de marches en interaction a été obtenu par la méthode du cylindre (méthode de la matrice de transfert avec conditions aux limites périodiques). Concernant les alliages, la face Cu83Pd17(1,1,5) a été étudiée par STM à température ambiante. Cette face présente une structure formée de marches simples qui contraste avec la structure en marches appariées de la face Cu83Pd17(1,1,11), en accord avec les prédictions théoriques. Enfin, la face vicinale de Cu3Au(1,1,11) a été étudiée par STM à température variable (entre 300 K et 700 K) et par diffraction d'hélium. On observe, sur cette surface, que les marches s'apparient sous la température critique TC (=663 K), tandis qu'au-dessus de TC la surface présente une structure marches simples qui facettent. Ces résultats illustrent les multiples manifestations de l'influence de l'ordre chimique sur la morphologie de surface.

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Loustau, Cazalet Charlotte. "Relation morphologie/réactivité des substrats lignocellulosiques : impact du prétraitement par explosion à la vapeur." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI099/document.

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Dans un contexte de transition énergétique et de lutte contre le réchauffement climatique, la production d’éthanol de seconde génération semble une voie très prometteuse afin de réduire notre dépendance aux énergies fossiles. Il existe 3 étapes clés pour la production de ce nouveau biocarburant : le prétraitement qui permet de déstructurer la matrice lignocellulosique afin de rendre la cellulose plus accessible aux enzymes, l’hydrolyse enzymatique qui a pour but de produire des sucres fermentescibles et la fermentation qui permet de transformer ces sucres en éthanol. Actuellement, le prétraitement considéré comme le plus efficace, et principalement retenu par les industriels, est le prétraitement par explosion à la vapeur. Cependant, certains aspects comme les effets physicochimiques induits par le prétraitement ainsi que leurs impacts sur les caractéristiques de la biomasse prétraitée restent encore mal compris.Schématiquement, le prétraitement par explosion vapeur peut se décomposer en deux étapes : la première se rapproche d’une cuisson acide réalisée à 150-200°C durant 5 30 min et permet principalement l’hydrolyse des hémicelluloses, alors que la seconde est une détente explosive qui permet un éclatement mécanique du substrat rendant potentiellement la cellulose plus réactive à l’hydrolyse enzymatique. Globalement les effets de ce type de prétraitement sur la biomasse lignocellulosique sont aujourd’hui bien connus mais la compréhension des différents phénomènes physico-chimiques ayant lieu en son sein reste limitée. En effet le découplage de l’étape de cuisson et de l’étape de détente est délicat car, la température du réacteur (qui impacte principalement les réactions de cuisson) est directement liée à sa pression (qui impacte principalement la détente) par la thermodynamique des phases.Ce travail de thèse se propose donc de mieux appréhender l’ensemble des phénomènes physico-chimiques ayant lieu durant le prétraitement par explosion à la vapeur en s’appuyant notamment sur une discrimination expérimentale des phénomènes chimiques (réactions de dépolymérisation) et des phénomènes physiques (détente explosive) ainsi que sur une caractérisation multi-techniques et multi-échelles de la biomasse lignocellulosique obtenue après ce type de prétraitement. L’objectif est aussi de comprendre quelles sont les principales caractéristiques de la biomasse qui expliquent les différences de réactivité observées lors de l’étape d’hydrolyse enzymatique et d’expliquer l’impact du prétraitement par explosion à la vapeur sur les propriétés physicochimiques et donc sur la réactivité
In a context of energy transition and climate change challenge, the production of second generation ethanol seems to be a very promising way to reduce our dependence on fossil fuels. There are 3 key steps for producing this new biofuel: pretreatment to decompose the lignocellulosic biomass and to make cellulose more accessible to enzyme attacks, enzymatic hydrolysis to produce fermentable sugars and fermentation to convert these sugars into ethanol. Currently, the pretreatment considered to be the most efficient, and mainly retained for industrialization, is the steam explosion pretreatment. However, some aspects such as the physicochemical effects induced by pretreatment and their impacts on the characteristics of pretreated biomass remain misunderstood.Schematically, the steam explosion pretreatment can be separated into two stages: the first is similar to an acid cooking carried out at 150-200°C during 5-30 min and allows mainly the hydrolysis of hemicelluloses, while the second is an explosive release which allows a mechanical bursting of the substrate potentially making the cellulose more reactive to enzymatic hydrolysis. As a whole, the effects of this type of pretreatment on lignocellulosic biomass are now well known, but the understanding of the different physicochemical phenomena occurring within it remains limited. Indeed, decoupling the cooking stage and the expansion stage is complicated because the reactor temperature (which mainly impacts the cooking reactions) is directly related to its pressure (which mainly impacts the explosive release) by the phase thermodynamics.This thesis work aims to better understand all the physicochemical phenomena occurring during a steam explosion pretreatment, based in particular on experimental discrimination of chemical phenomena (depolymerization reactions) and physical phenomena (explosive release) as well as on a multi-technical and multi-scale characterization of the lignocellulosic biomass obtained after this type of pretreatment. The objective is also to understand what are the main characteristics of biomass that explain the differences in reactivity observed during the enzymatic hydrolysis step and to explain the impact of the steam explosion pretreatment on the physicochemical properties and therefore the reactivity

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Goapper, Sylvain. "Morphologie de surface et ordre chimique : Faces vicinales d'alliage cuivre-palladium." Phd thesis, Université de Marne la Vallée, 1998. http://tel.archives-ouvertes.fr/tel-00243115.

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L'objet de cette thèse a été de caractériser la distribution des marches atomiques sur une surface vicinale d'alliage Cu-17%Pd(1,1,11) de structure ordonnée L12. Cet alliage présente une transition chimique ordre-désordre à 778 K (Tc) (1er ordre). Par une observation directe en STM et par diffraction d'hélium, nous avons observé que la face vicinale a une structure en marches appariées à température ambiante. En fonction de la température, on montre que la morphologie de la surface transite de façon continue vers une structure de marches simples pour une température proche de Tc.

La diffraction de rayons X à l'ESRF nous a permis d'observer l'apparition du désordre chimique à la surface et l'évolution simultanée du changement de structure des marches. On observe que la séparation des paires de marches évolue proportionnellement à la composante parallèle du paramètre d'ordre dans le plan de surface.

Pour des temps courts de mise en ordre, le STM montre une structure en domaines, des marches appariées. On identifie les frontières entre domaines par le dédoublement local des paires de marches. Ce phénomène traduit l'émergence à la surface de parois. Cette structure en domaine, caractéristique de l'ordre chimique dans les premiers plans de surface, nous a permis, par STM et diffraction d'hélium, de suivre la cinétique de mise en ordre en présence d'une surface. La taille caractéristique des domaines évolue avec le temps de recuit en A(T).t1/2. Un diagramme d'Arrhénius du facteur d'échelle temporel A(T) a permis de mesurer une énergie d'activation de mise en ordre de 2 eV à la surface ainsi qu'en volume.

Dans une seconde étude, nous avons caractérisé l'influence du dépôt de palladium sur une surface vicinale de cuivre. Nous avons montré par diffraction d'hélium que cet alliage de surface provoque un appariement des marches similaires à celles observées sur l'alliage massif Cu3Pd. Cependant, cette modification de la distribution des marches présente un faible degré d'ordre qui peut être du à l'absence d'ordre chimique à longue distance.

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46

Cappello, Giovanni. "Stabilisation et morphologie de la surface de symétrie cinq du quasicristal Al70Pd20Mn10." Université Joseph Fourier (Grenoble), 1999. https://tel.archives-ouvertes.fr/tel-01140300.

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Les quasicristaux sont des materiaux non periodiques, avec un ordre d'orientation a longue portee et qui presentent un axe de symetrie d'ordre cinq. La physique des surfaces ne permet pas de decrire, a priori, la structure et la morphologie de la surface d'un quasicristal. Nous avons donc etudie les aspects structuraux et morphologiques de la surface de symetrie cinq du quasicristal alpdmn. Cette surface a ete preparee par bombardement ionique et recuit sous ultravide. Nous avons explore le diagramme de phase de cette surface en fonction de la temperature du recuit : apres bombardement et recuit a basse temperature, on observe l'apparition d'une phase cristalline en epitaxie sur le quasicristal. Un recuit a plus haute temperature (t > 700k) permet d'obtenir une surface quasicristalline de bonne qualite. La composition chimique de la surface a ete caracterisee par spectroscopie d'electrons (auger et xps) et sa structure par diffraction d'electrons lents (leed). Des mesure de microscopie en champ proche (afm a l'air et stm sous ultra vide) et de diffraction des rayons x in situ ont montre que la morphologie de cette surface est dominee, a l'echelle du micron, par une structure en terrasses et marches macroscopiques et, a l'echelle du nanometre, par une structure en clusters. Nous avons observe que des recuits a plus haute temperature (t > 900k) induisent une transformation irreversible de la surface, qui evolue vers une surface plate et qui peut se decrire en terme de marches et terrasses jusqu'a l'echelle du nanometre. Dans la derniere partie de la these, on presente une experience de generation d'ondes stationnaires dans le quasicristal. Nous avons montre la reponse de la surface du quasicristal au passage d'une onde stationnaire et la possibilite de sonder, par cette technique, la relation de coherence entre la surface et le volume du quasicristal.

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Ma, Li. "Premières étapes d’oxydation d’un acier inoxydable austénitique et influence sur la passivation." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEC034.

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Le but de cette recherche est de comprendre le rôle de la résistance à l'amorçage de la corrosion des hétérogénéités chimiques et structurelles créées dans la passivation par les mécanismes d'oxydation/passivation des surfaces d'alliage contenant du Cr. Ceci sera réalisé en utilisant un système UHV permettant la surveillance de la croissance de l'oxyde pendant et après l'exposition à l'oxygène par XPS et STM, et permettant aussi le transfert direct (sans exposition à l'air) à une boîte à gants remplie d'argon équipée d'une cellule électrochimique pour contrôler précisement de l'exposition aux électrolytes aqueux agressifs. Les environnements aqueux corrosifs avec des conditions agressives contrôlées (pH, potentiel électrochimique, concentration en chlorure) peuvent résulter des modifications de surface (chimiques et nanostructurales) qui sont observées par XPS et STM. La croissance du film passif et l'enrichissement en chrome seront analysés in situ par XPS et par STM afin de comprendre l'effet des paramètres d'oxydation sur le comportement local
The aim of this research proposal is to understand the role in the corrosion initiation resistance of the chemical and structural heterogeneities created in the passivating oxide by the oxidation/passivation mechanisms of Cr-containing alloy surfaces. This will be achieved using a UHV system enabling XPS and STM monitoring of oxide growth during and after oxygen exposure and direct transfer without air exposure to an argon-filled glove box equipped with an electrochemical cell for precise control of exposure to aggressive aqueous electrolytes. The aqueous corrosive environments in controlled aggressive conditions (pH, electrochemical potential, chloride concentration) can results the surface modifications (chemical and nanostructural) will be analyzed by XPS and STM. Passive film growth and chromium enrichment will be analyzed in situ by XPS and by STM so as to understand the effect of the oxidation parameters on the local behaviour

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Chevalier, Eric. "Les surfaces à marches des cristaux d'hélium 4." Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10150.

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Le travail presente dans ce memoire est une mesure experimentale des proprietes des surfaces a marches, surfaces faiblement desorientees par rapport a l'axe cristallographique c, des cristaux d'helium-4, a partir des ondes de fusion-cristallisation. Nous montrons pour la premiere fois, l'existence d'un passage entre le regime rugueux et le regime a marches en fonction de l'angle. Nous le mettons en evidence par la mesure independante des deux composantes transverses et longitudinales du tenseur de rigidite de surface. Dans le regime a marches, nous avons non seulement montre que l'interaction repulsive entre les marches cristallines est bien proportionnelle a l'inverse de la distance entre marches au carre, mais avons aussi mesure a la fois la contribution entropique et elastique de cette interaction

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Mantilla, Miguel. "Structure de films supportés : polarité de films MgO/Ag (111)- évolution de la morphologie d'agrégats Au/ TiO2(111) lors de la réaction catalytique d'oxydation du Co." Paris 6, 2009. http://www.theses.fr/2009PA066195.

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L’observation in situ de nano-objets en cours de croissance ou lors d’une réaction est un objectif important pour les nanosciences. Le présent travail porte sur deux thématiques qui relèvent de cette approche : -la croissance de films d’oxyde de magnésium MgO d’orientation polaire et -la caractérisation de films Au/TiO2(110) catalytiques. Peu de films d’orientation polaire ont été synthétisés à ce jour. La formation de films MgO par oxydation de Mg/Ag(111) est analysé ici par microscopie tunnel (STM). Les symétries 3 ou 6 excluent l’orientation MgO(100) et suggèrent l’existence de films MgO d’orientation polaire. Des hauteurs apparentes ~ 120 pm sont cohérentes avec l’hypothèse de la formation de films de structure de type NaCl orientés suivant (111). Les périodicités à longue distance qui sont mises en évidence par STM sont attribuées à des mailles de coïncidence MgO(111)/Ag(111). Très débattue, l’activité de l’or catalytique supporté dépend fortement de la taille des particules et n’est effective que pour des diamètres < 5 nm. Deux types de mécanisme sont proposés, l’un fondé sur un effet quantique associé à des particules bidimensionnelles, l’autre sur un rôle accru de la surface pour des particules tridimensionnelles de petite taille. L’objectif du travail présenté est de caractériser la les agrégats d’or in situ, pendant la réaction d’oxydation du CO, dans le cadre d’une analyse simultanée de la morphologie, de la cristallographie et de la réactivité des particules (seuls les résultats de l’étude de réactivité sont évoqués ici). Les films Au/TiO2(110) sont examinées par diffraction des rayons X aux petits (GISAXS) et aux grands (GIXS) angles. La réactivité est observable pour des agrégats de taille ≈ 5 nm et augmente au fur et à mesure que la taille des particules décroît. Il est remarquable que, même aux plus faibles tailles explorées (1,7 nm de diamètre), les agrégats d’or Au(111)/TiO2(110) sont tridimensionnels. La forte relaxation du paramètre provoquée par l’adsorption de l’oxygène démontre que l’oxygène est chimisorbé sur l’or et qu’il couvre une part significative de la surface de l’agrégat. La mise en place de la réaction catalytique qui suit l’introduction de CO provoque un mûrissement des particules, qui est attribué à l’échauffement local dû à la réaction d’oxydation, et une rotation de 4. 9° des agrégats qui témoigne de l’existence de sites préférentiels à l’interface Au(111)/TiO2(110).

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Wouters, Yves. "Oxydation thermique des métaux dans la vapeur d'eau : cas du nickel et du titane." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0056.

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Les cinetiques d'oxydation a haute temperature de nombreux metaux et alliages metalliques, ainsi que la morphologie des couches de corrosion formees, peuvent etre tres influencees par la presence de vapeur d'eau dans l'atmosphere oxydante. Cependant l'interpretation des resultats est la plupart du temps vague et les mecanismes d'oxydation restent mal connus. Pour porter un eclairage nouveau sur ce domaine de la cinetique heterogene, cette these tente de relier les aspects classiques de modelisation macroscopique de l'oxydation thermique des metaux et ceux, plus novateurs, de perception microscopique des phenomenes physiques impliques. Pour ce faire, nous avons mene une etude cinetique parametrique et une caracterisation des couches utilisant notamment les methodes photo-electrochimiques ex-situ, dans le cas du nickel et du titane. Pour la premiere fois, l'utilisation systematique de la photo-electrochimie, apporte des eclairages inattendus sur les ecarts a la stoechiometrie, le niveau de contrainte et la nature des defauts des oxydes formes. Ces resultats permettent de proposer une modelisation cinetique en accord avec la totalite des observations experimentales

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Dissertations / Theses on the topic 'Morphology of stem'

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