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 Collection: UNT Theses and Dissertations
Effect of Retting on Surface Chemistry and Mechanical Performance Interactions in Natural Fibers for High Performance Polymer Composites

Effect of Retting on Surface Chemistry and Mechanical Performance Interactions in Natural Fibers for High Performance Polymer Composites

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Date: May 2013
Creator: Ramesh, Dinesh
Description: Sustainability through replacement of non-renewable fibers with renewable fibers is an ecological need. Impact of transportation costs from South-east Asia on the life cycle analysis of the composite is detrimental. Kenaf is an easily grown crop in America. Farm based processing involves placing the harvested crop in rivers and ponds, where retting of the fibers from the plant (separation into fibers) can take 2 weeks or more. The objective of this thesis is to analyze industrially viable processes for generating fibers and examine their synergistic impact on mechanical performance, surface topography and chemistry for functional composites. Comparison has been made with commercial and conventional retting process, including alkali retting, enzymatic retting, retting in river and pond water (retting occurs by natural microbial population) with controlled microbial retting. The resulting kenaf fibers were characterized by dynamic mechanical analysis (DMA), Raman spectroscopy (FT-Raman), Fourier transform infrared spectroscopy (FT-IR), polarized optical microscopy (POM), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) optical fluorescence microscopy, atomic force microscopy (AFM) and carbohydrate analysis. DMA results showed that pectinase and microbe treated fibers have superior viscoelastic properties compared to alkali retting. XPS, Raman, FT-IR and biochemical analysis indicated that the controlled microbial and pectinase retting was ...
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Electrochemically Deposited Metal Alloy-silicate Nanocomposite Corrosion Resistant Materials

Electrochemically Deposited Metal Alloy-silicate Nanocomposite Corrosion Resistant Materials

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Date: May 2013
Creator: Conrad, Heidi Ann
Description: Zinc-nickel ?-phase silicate and copper-nickel silicate corrosion resistant coatings have been prepared via electrochemical methods to improve currently available corrosion resistant materials in the oil and gas industry. A layered silicate, montmorillonite, has been incorporated into the coatings for increased corrosion protection. For the zinc nickel silicate coatings, optimal plating conditions were determined to be a working pH range of 9.3 -9.5 with a borate based electrolyte solution, resulting in more uniform deposits and better corrosion protection of the basis metal as compared to acidic conditions. Quality, strongly adhering deposits were obtained quickly with strong, even overall coverage of the metal substrate. The corrosion current of the zinc-nickel-silicate coating is Icorr = 3.33E-6 for a borate based bath as compared to a zinc-nickel bath without silicate incorporation (Icorr = 3.52E-5). Step potential and direct potential methods were examined, showing a morphological advantage to step potential deposition. The effect of borate addition was examined in relation to zinc, nickel and zinc-nickel alloy deposition. Borate was found to affect the onset of hydrogen evolution and was examined for absorption onto the electrode surface. For copper-nickel silicate coatings, optimal conditions were determined to be a citrate based electrolytic bath, with pH = 6. ...
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Expression of G-protein Coupled Receptors in Young and Mature Thrombocytes and Knockdown of Gpr18 in Zebrafish

Expression of G-protein Coupled Receptors in Young and Mature Thrombocytes and Knockdown of Gpr18 in Zebrafish

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Date: May 2013
Creator: Potbhare, Vrinda Nikhil
Description: In this study, a novel method based on biotinylated antibodies and streptavidin coated magnetic beads was used to separate the thrombocyte subpopulations from zebrafish whole blood. DiI-C18, a lipophilic dye, labels only young thrombocytes when used at low concentrations. Commercially available biotinylated anti-Cy3 antibody was used to label the chromophore of DiI-C18 on the young thrombocytes and streptavidin coated magnetic beads were added subsequently, to separate young thrombocytes. The remaining blood cells were probed with custom-made biotinylated anti-GPIIb antibody and streptavidin magnetic beads to separate them from other cells. Further, thrombocytes are equivalents of mammalian platelets. Platelets play a crucial role in thrombus formation. The G-protein coupled receptors (GPCRs) present on the platelet surface are involved during platelet activation and aggregation processes. So, thrombocytes were studied for the presence of GPCRs. The GPCR mRNA transcripts expressed in the young and mature thrombocytes were subjected to densitometry analysis and pixel intensities of the bands were compared using one way ANOVA. This analysis did not show significant differences between the young and mature GPCR mRNA transcripts but identified a novel GPCR, GPR18 that was not reported in platelets earlier. To study the function of this GPCR, it was knocked down using GPR18 ...
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The Girl Disappeared: the Prostitute of La Isla De Santa Flora

The Girl Disappeared: the Prostitute of La Isla De Santa Flora

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Date: May 2013
Creator: Winston, Michael
Description: The novella, The Girl Disappeared, focuses on the life of Emalia, a street kid from Mexico. She is taken from the streets of Veracruz and forced into a life of prostitution on the fictitious island of La Isla de Santa Flora. The primary conflict that drives the action of the story is her pending choice between escaping her life of slavery and saving another young woman who is on the verge of being forced into a life of prostitution as well. The novella, as a literary piece, dwells on the question of character agency and explores the multilayered nature of code switching. Language for these women becomes a tool in their struggle against their captives and a means of self-preservation, or sanctuary, as they use their growing bilingualism to foment a limited agency, to act in their own defense.
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Interspecimen Study of Bone to Relate Macromechanical, Nanomechanical and Compositional Changes Across the Femoral Cortex of Bone

Interspecimen Study of Bone to Relate Macromechanical, Nanomechanical and Compositional Changes Across the Femoral Cortex of Bone

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Date: May 2013
Creator: Nar, Mangesh
Description: Mechanics of bone is widely studied and researched, mainly for the study of fracture. This has been done mostly on a macro scale. In this work hierarchical nature of bone has been explored to investigate bone mechanics in more detail. Flexural test were done to classify the bones according to their strength and deflection. Raman spectroscopy analysis was done to map the mineralization, collagen crosslinking changes across the thickness of the bone. Nanoindentation was done to map indentation hardness and indentation modulus across femoral cortex of the bone. The results indicate that the composition of the bone changes across the thickness of the femoral cortex. The hypothesis is confirmed as increase in mineralization, carbonate to phosphate ratio and collagen crosslinking shows the effect as increased indentation hardness and modulus and decreased deflection.
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Investigating Postpartum Depression in Southern Rural Egypt and Effects of Sertraline on Fsh and Lh Gene Expression on Fathead Minnows Using Rt-pcr

Investigating Postpartum Depression in Southern Rural Egypt and Effects of Sertraline on Fsh and Lh Gene Expression on Fathead Minnows Using Rt-pcr

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Date: May 2013
Creator: Mohamed, Hagar Abdo
Description: Postpartum depression (PPD) is a major health problem that affects many women worldwide. In Egypt, PPD is neglected despite the expected high prevalence rate among women during the transition period after the Egyptian revolution. This research investigated the prevalence, risk factors, and interventions of postpartum depression in southern rural Egypt. Interviews were conducted with 57 participants recruited from public and private hospitals. Questionnaires and the Arabic version of the Edinburgh Postnatal Depression Scale were administered. The prevalence of PPD is 73.7%. PPD is associated with low income and age at childbirth. Most participants regarded screening mothers after childbirth for PPD as effective; in comparison to, antidepressants that were regarded by most participants as ineffective. Women in southern rural Egypt prefer high number of pregnancies, so investigating the influence of sertraline, an antidepressant medication, on female hormones becomes important. In this research, fathead minnows were exposed to 3 and 10 ppb sertraline for 7 days. Real-time Polymerase Chain Reaction was used to detect the change in gene expression of the Follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Results showed that a down regulation at the 10 ppb was evident on the LH and to a lesser extent on FSH. Our results ...
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My Crown Is in My Heart, Not on My Head: Heart Burial in England, France, and the Holy Roman Empire From Medieval Times to the Present

My Crown Is in My Heart, Not on My Head: Heart Burial in England, France, and the Holy Roman Empire From Medieval Times to the Present

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Date: May 2013
Creator: Duch, Anna M.
Description: Heart burial is a funerary practice that has been performed since the early medieval period. However, relatively little scholarship has been published on it in English. Heart burial began as a pragmatic way to preserve a body, but it became a meaningful tradition in Western Europe during the medieval and early modern periods. In an anthropological context, the ritual served the needs of elites and the societies they governed. Elites used heart burial not only to preserve their bodies, but to express devotion, stabilize the social order and advocate legitimacy, and even gain heaven. Heart burial assisted in the elite Christian, his or her family, and society pass through the liminal period of death. Over the centuries, heart burial evolved to remain relevant. The practice is extant to the present day, though the motivations behind it are very different from those of the medieval and early modern periods.
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Novel Role of Trypsin in Zebrafish

Novel Role of Trypsin in Zebrafish

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Date: May 2013
Creator: Alsrhani, Abdullah Falleh
Description: It has been shown previously in our laboratory that zebrafish produce trypsin from their gills when they are under stress, and this trypsin is involved in thrombocyte activation via PAR2 during gill bleeding. In this study, I investigated another role of the trypsin that is secreted from zebrafish. This investigation has demonstrated a novel role of trypsin in zebrafish. Not only did this investigation demonstrate the role of trypsin in zebrafish behavior, but also it showed that PAR2 might be the receptor that is involved in trypsin-mediated behavioral response. In addition, we have shown that Gq and ERK inhibitors are able to block the trypsin pathway and prevent the escaping behavior. Finally, the results of this investigation suggest that the cells that respond to trypsin are surface cells, which have an appearance similar to that of neuromast cells.
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Primary Cilia in the Oligodendrocyte Lineage

Primary Cilia in the Oligodendrocyte Lineage

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Date: May 2013
Creator: Hao, Yung-Chia
Description: oligodendrocytes migrate from the corpus callosum into the overlying cortex. The incidence of cilia did not change markedly across age groups, and did not vary consistently with the number of processes per cell, which was used as an indication of the maturation stage of OPCs and young OLs. The mean percent of Olig1 immunopositive (Olig1+) cells having cilia across ages was 33.1% + 16.5%, with all ages combined. In O4+ cells of these mice, 56.7 + 3.6% had primary cilia. If it is the case that adult OLs do not have cilia, the point in the lineage when primary cilia are lost is still unknown. Adult mice that had been injected with cyclopamine to block cilia-dependent Shh signaling were examined to determine whether the rate of generating new OPCs was influenced. In the CC of control mice, the numerical density of Olig1+/BrdU+ cells was 1.29 + 0.07/mm2 was reduced to 0.68 + 0.38/mm2 in the cyclopamine-injected group, and the numerical density of all BrdU+ cells (including both Olig1+ and Olig1- cells) of 4.55 + 1.50/mm2 in the control group was reduced to 3.14 + 1.27/mm2 in the cyclopamine-injected group. However, there were only 2 mice in each group and the ...
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Warrior Women in Early Modern Literature

Warrior Women in Early Modern Literature

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Date: May 2013
Creator: Oxendine, Jessica Grace
Description: Fantasies about warrior women circulated in many forms of writing in early modern England: travel narratives such as Sir Walter Ralegh's The Discoverie of Guiana (1595) portray Amazon encounters in the New World; poems like Edmund Spenser's The Faerie Queene (1596) depict women's skill with a spear; and the plays of Shakespeare, John Fletcher, and others stage the adventurous feats of women on the battlefield. In this dissertation, I analyze the social anxieties that emerge when warrior women threaten gender hierarchies in the patriarchal society of early modern England. The battlefield has traditionally been a site for men to prove their masculinity against other men, so when male characters find themselves submitting to a sword-wielding woman, they are forced to reimagine their own masculine identities as they become the objects acted upon by women. In their experience of subjectivity, these literary warrior women often allude to the historical Queen Elizabeth I, whose reign destabilized ideas about gender and power in the period. Negative evaluations of warrior women often indicate anxiety about Elizabeth as an Amazon-like queen. Thus, portrayals of warrior women often end with a celebration of patriarchal dominance once the male characters have successfully contained the threat of the ...
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