Pitch material is an important precursor in the production of carbon bre, carbon composites and synthetic graphite. It has a complex transformation during pyrolysis which incorporates the separation of a liquid crystalline phase, known as mesophase. This thesis attempts to enhance the understanding of this change in composition, structure and its resultant behaviour. In this study, two pitches, a coal-tar pitch (MP110) and a (SASOL) Lurgi-gasi er pitch, are pyrolised to produce material at di erent stages of mesophase development. These pitches produce mesophase of di erent mosaic type and therefore also resultant coke. The MP110 was thermally treated up to a temperature of 437 and produced anisotropic pitch (which still contains signi cant particulate matter). The nucleated mesophase spheres did not coalesce to produce domains; this behaviour being attributed to the particulate material. The SASOL pitch produced a di erent type of mesophase material. The mesophase produced was of ne mosaic domains; a sample with continuous mesophase regions was also produced with a mesophase content of approximately 60% (by volume). The aromatic starting material of MP110 produced higher quinolone and toluene insoluble (QI and TI) compounds after pyrolysis. This was also observed in the increase of C/H (molar ratio of carbon to hydrogen). The more aliphatic SASOL starting pitch showed similar trends to its MP110 counterparts with respect to QI (quinoline insolubles), TI (toluene insolubles) and C/H. The glass transition and associated temperatures of the pitches were analysed via thermal mechanical analysis (TMA), dynamic scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The techniques showed consistency between instruments, with TMA providing the likeliest re ection of the true thermodynamic glass transition temperature. The loss of volatile components was accompanied by an increase in glass transition temperature (observed in conjunction with C/H and mesophase content). For anisotropic MP110 pitches, two relaxations were observed, one for the isotropic fraction, the other for the mesophase. No such behaviour was easily observed for the SASOL pitches. Rheological measurements were obtained to understand the behaviour of the pitches. Measurements were limited to a speci c viscosity range. The measurements of the samples were therefore made at di erent temperatures. The relation of the measurement temperature to the glass transition temperature is thus of extreme importance. The temperature governs the state of the structure; whether it be suspension, emulsion or gel. Oscillatory shear experiments were undertaken for the pitch material. Predominantly isotropic material showed transition from viscoelastic solid to viscoelastic liquid as previously observed in pitch material. The anisotropic MP110 pitches did not allow for the production of mastercurves due to non-linear viscoelastic e ects caused by the softening of mesophase. This being the transition from a suspension of hard spheres to an emulsion of deformable droplets (depending on temperature). For the higher mesophase content anisotropic SASOL pitches, mastercurves were produced; it had a similar shape to the isotropic pitches (at temperatures closer to the glass transition), but signi cantly increased elasticity was observed at higher temperatures. This phenomenon supported the hypothesis of a strong interaction between the components and phases of the pitch, and thus the possibility of gelled systems. Rotational shear-rheometry was also utilised and showed that isotropic pitch material behaves as a predominantly isoviscous uid. The anisotropic MP110 pitches of approximately 30% mesophase showed high- and low-shear viscosity plateau uid behaviour. This being caused by the breakup of agglomerated mesophase spheres. This was tested by the implementation of the Krieger- Dougherty suspension model. The possibility of droplet deformation was investigated for these samples by utilising a Krieger-Douherty based emulsion analogue, which con- rmed suspension like behaviour (at the measured temperatures). MP110 samples with more mesophase were measured at higher temperatures. Their behaviour is more akin to Power-law shear-thinning behaviour. Being further away from the continuous isotropic phase glass transition temperature, the behaviour observed is similar to that of emulsions. SASOL anisotropic pitches showed signi cant yielding upon shear, which is attributed to structure breakdown. This behaviour is appropriately described by a yield stress, shearthinning model such as Herschel-Bulkley. Measurements of viscosity for these samples were made at temperatures signi cantly further from the glass transition temperature as compared to that of the MP110 pitches. This corroborates strong interaction between its components. The observed shapes of the curve, at temperatures of measurement, support the notion of a gel structure. This behaviour is rst proposed via the complex structure observed (clusters of ne mosaic mesophase domains) and supported by strong interaction of the components inferred from obtained rheological properties. / Thesis (PhD)--University of Pretoria, 2015. / tm2015 / Chemical Engineering / PhD / Unrestricted

Förpackningsmaterial av plast är idag vida använt inom livsmedelsindustrin för att skydda livsmedel under transport, förvaring och tillagning. Vid tillverkning av plast används ett flertal olika additiv som visat sig kunna migrera till livsmedel och verka hormonstörande. Migrationen av ämnen från förpackningsmaterial påverkas av flera parametrar så som temperatur, förvaringstid, livsmedlets egenskaper som till exempel fetthalt eller aciditet samt det migrerade ämnenas egenskaper. Syftet med studien var att undersöka förekomst av östrogenlika ämnen i ett vanligt förekommande förpackningsmaterialet (TPH100) som används vid förvaring och uppvärmning samt om dessa ämnen migrerar till livsmedel under olika förhållanden. I Studien användes två livsmedelssimulanter, ättiksyra 3% (B) samt etanol 50% (D1) specificerade i gällande direktiv inom Europa. Temperaturens påverkan på migration från förpackningsmaterialet till livsmedelssimulantlösningarna undersöktes genom kylskåpsförvaring samt kylskåpsförvaring med efterföljande uppvärmning i ugn. Förekomst av östrogenlika ämnen i materialet och livsmedelssimulantlösningar analyserades med en mekanismspecifik östrogenreceptor (ER)-baserad bioanalys U2OS-ERα CALUX. För att undersöka om den östrogenlika aktiviteten som uppmättes i materialet kom från PAHer analyserades provet även med en aryl hydrocarbon (Ah)-receptor baserad bioanalys HII4E-luc. Studiens resultat visade förekomst av ämnen i förpackningsmaterialet som kunde binda till och aktivera östrogenreceptor ERα (4.1 pg EEQ/g plast). Vidare indikerade resultaten att dessa ämnen kan migrera till livsmedel med likvärdig aciditet som livsmedelssimulant B (< pH 4,5) vid upphettning till 121 Cº i ugn under en timme. Migrationen från materialet under dessa förhållanden var 1,1-2,0 pg EEQ/g. För livsmedelssimulant B uppmättes ingen kvantifierbar migration vid kylskåpsförvaring. Resultaten för livsmedelssimulant D1 vid kylskåpsförvaring och/eller uppvärmning visade att det inte förekom någon migration till livsmedel med hög fetthalt i kvantifierbara mängder. Ingen kvantifierbar Ah-receptor aktivitet kunde detekteras med HII4E-luc bioanalysen vilket visar att det troligen inte var PAHer som orsakade den östrogenlika effekten. Resultaten indikerar att materialet innehåller och kan avge kvantifierbara mängder östrogenlika ämnen till livsmedel vid användning. Vidare studier med kemiskanalys behövs för att identifiera vilka ämnen som orsakat effekten i bioanalysen.

Thymic stromal lymphopoietin (TSLP) produced by epithelial cells acts on dendritic cells (DCs) to drive differentiation of TH2-cells, and is therefore important in allergic disease pathogenesis. However, DCs themselves make significant amounts of TSLP in response to microbial products, but little is known about the key downstream signals that induce and modulate this TSLP secretion from human DCs. We show that human monocyte derived DC (mDC) secretion of TSLP in response to Candida albicans and β-glucans requires dectin-1, Syk, NF-κB, and p38 MAPK signaling. In addition, TSLP production by mDCs is greatly enhanced by IL-1β, but not TNF-α, in contrast to epithelial cells. Furthermore, TSLP secretion is significantly increased by signals emanating from the endoplasmic reticulum (ER) stress response, specifically the unfolded protein response sensors, inositol-requiring transmembrane kinase/endonuclease 1 and protein kinase R-like ER kinase, which are activated by dectin-1 stimulation. Thus, TSLP production by mDCs requires the integration of signals from dectin-1, the IL-1 receptor, and ER stress signaling pathways. Autocrine TSLP production is likely to play a role in mDC-controlled immune responses at sites removed from epithelial cell production of the cytokine, such as lymphoid tissue.

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In this dissertation, I explore how crossing national borders has made me aware of the many identity borders that I have crossed as a transnational Chinese, and how I am caught up in identity politics between the “Chinese,” who do not necessarily always identify as “Chinese” in the transnational context. However, as a racialized group in the U.S., transnational Chinese are perceived as a homogeneous population, usually through racially (“Yellow Peril” or “Chinese Virus”) and politically (“Red Scare”) charged lenses measured by Western/U.S. binaristic and hierarchical standards. Therefore, in this research project, I problematize dominant U.S. race logic, i.e., the White/Non-White binary, for its limited capabilities of understanding and explaining identity, communication, culture, and power in an increasingly interconnected world; and I also call for an alternative theorizing of race and identity in the transnational context. Border crossings within the conditions of contemporary globalization have intensified interconnectivities and complicated how we comprehend and communicate our identities. It thus becomes essential to find ways to “unsettle and restage” racial and cultural differences in the context of globalization (Shome & Hegde, 2002a, p. 174-5). With a different skin color, speaking English with a foreign accent while being perceived as “Model Minorities,” transnational Chinese have lately been ascribed with another pathologized identity label: “Chinese Virus,” which may be understood as an extension of the “Yellow Peril” rhetoric. Furthermore, within the Chinese communities, due to historical reasons, colonialism, political unrest, and civil war, many Taiwanese and Hong Kongers identify themselves very differently from mainland Chinese. When crossing borders to live together in the U.S., the identity tensions among Chinese ethnicities in addition to the interracial confrontations between transnational Chinese and local racial groups only make understanding what it means to be Chinese on the racial landscape of the U.S. even more complex.I weave together Yep’s (2010) notion of thick(er) intersectionalities and Kraidy’s (2005) description of transnationalism to build my conceptual framework. On the one hand, thick(er) intersectionalities advocates for more complex and embodied ways of theorizing intersectional identities and “the interplay between individual subjectivity, personal agency, systemic arrangements, and structural forces” (p. 173). On the other, transnationalism helps make sense of transnational identities with “a shifting location of contradictions that straddles multiple viewpoints,” which cannot be defined “in binary and essentialist terms” (Bardhan & Zhang, 2017, p. 288). I thus examine why an in-depth, transnational understanding of Chinese identity is necessary and how to move toward such an understanding, including that of racial, cultural, linguistic, and political identities of transnational Chinese living in the U.S., especially in the context of the current trade tensions between the U.S. and China, two nations tightly connected economically while largely differing culturally and politically.Methodologically, I employ a mixed-method approach by applying autoethnography and in-depth interview as my primary research methods. The dissertation mainly addresses three research questions through a communicative lens: 1) What does it mean to live in the U.S. as transnational Chinese? 2) How do transnational Chinese make sense of Chinese-ness(es) in such a context? 3) What is at stake in understanding Chinese-ness in a transnational context that necessitates an alternative theorization of race to the dominant/White U.S. race ideology? The findings show that there is no singular definition of what Chinese-ness(es) is(are) and what it(they) entail(s). It is a thick and fluid concept that is unique to each transnational Chinese based on their lived experiences and subjected to their own understandings while also constrained in the larger social framework by Chinese and U.S. cultural scripts and contexts. Chinese-ness, to transnational Chinese, cannot be compartmentalized in the limited identity categories specific to either cultural context. Being exposed to a broader world with multiple cultural references, they are flexible enough to creatively identify, dis-identify, or even counter-identify with either their avowed identities, or ascribed identities, or both in either or both cultural contexts. The complexities, specificities, and particularities of their transnational identity experiences, thus, cannot be adequately understood within the confines of simple intersections of U.S.-centric identity categories. I conclude that Chinese-ness(es) is local and global, racial and ethnic, cultural and political, and spatial and temporal. There is no such thing as a singular, uniform Chinese-ness. Not even in the imaginary. This study may contribute to critical intercultural communication scholarship by situating knowledge of race, identity, and power in a very specific and complex context that includes the U.S. but is transnational in scope. Further, with an aim to provincialize dominant U.S. race logic, it makes an effort to transnationalize and internationalize theorizing of race and identity. Finally, speaking in a voice from a non-Western perspective currently situated in the West, I practice self-reflexivity throughout my writing with the hope of avoiding re-essentializing identity, race, and power in a covert “oppressor-oppressed” Manichean dualism that I attempt to deconstruct.

The number of people living with diabetes worldwide is continually increasing. The majority of these people will eventually die of cardiovascular disease, the major underlying cause of which is atherosclerosis. Despite the efforts of many researchers, gaps in our knowledge still exist regarding the molecular mechanism(s) linking the two conditions. Current data suggests that the hexosamine biosynthetic pathway (HBP) may have a role in the development of hyperglycemia-accelerated atherosclerosis. About 2-3% of glucose entering a cell is diverted into this pathway where it is modified through a series of reactions to yield the end product, UDP-N-acetylglucosamine (UDP-GlcNAc); a substrate for both N- and O-linked glycosylation of various molecules. N-linked glycosylation occurs in the endoplasmic reticulum (ER) and is an important process in the maintenance of ER homeostasis. We hypothesized that a dysregulation in the HBP can ultimately trigger ER stress – an event associated with the development of atherosclerosis. We have established a method that allows us to monitor levels of UDP-GlcNAc both in cultured cells and mouse tissues through high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS). Using this technique, we’ve shown that both glucosamine supplementation and overexpression of the rate limiting enzyme of the HBP, GFAT, in cultured cells results in elevated UDP-GlcNAc levels. Furthermore, glucosamine was shown to trigger ER stress. In contrast, three GFAT inhibitors that were previously identified in a high throughput screen were shown to decrease UDP-GlcNAc levels and one inhibitor, dehydroiso-β-lapachone, appears to prevent ER stress induction. Finally, we use complementary methods to show that the HBP is augmented in the livers of hyperglycemic mice. This process may play a role in the accelerated development of atherosclerosis. Together, these results provide further insight into the role of the HBP in diabetic atherosclerosis and the established methods provide a platform for the further investigation of this mechanism. / Thesis / Master of Science (MSc)

Major diseases such as cardiovascular diseases, diabetes, obesity and tumor growth are known to involve inflammatory angiogenesis. MCP-induced protein 1 (MCPIP1) encoded by ZC3H12A gene, was reported to promote angiogenesis and is addressed in my dissertation as MCPIP. The mechanism/s involved in the angiogenic differentiation induced by MCPIP was however unknown. The aim of this study was to bridge this gap in our knowledge and delineate the molecular mechanisms and sequential processes involved in angiogenesis mediated via MCPIP. To determine if angiogenesis induced by inflammatory cytokines, TNF-, IL-1 and IL-8 is mediated via induction of MCPIP, knockdown of MCPIP by its specific siRNA, in human umbilical vein endothelial cells was performed. Oxidative stress, ER stress and autophagy are known to be involved in mediating inflammation. We hypothesized that MCPIP-induced angiogenic differentiation is mediated via induction of oxidative stress, ER stress and autophagy. Chemical inhibitors and specific gene knockdown approach were used to inhibit each process postulated. Oxidative stress was inhibited by apocynin or cerium oxide nanoparticles or knockdown of NADPH oxidase subunit, phox47. Endoplasmic reticulum (ER) stress was blocked by tauroursodeoxycholate or knockdown of ER stress signaling protein IRE-1 and autophagy was inhibited by the use of 3methyl adenine, or LY 294002 or by specific knockdown of beclin1. Matrigel assay was used as an in vitro tool to assay angiogenic differentiation. Inhibition of each step inhibited the subsequent steps postulated. The results reveal that angiogenesis induced by inflammatory agents is mediated via sequential induction of MCPIP that causes v oxidative and nitrosative stress resulting in ER stress leading to autophagy required for angiogenesis. MCPIP has deubiquitinase and anti-dicer RNase activities. If and how the dual enzymatic activities of MCPIP mediate angiogenesis was unknown. Our results showed that hypoxia-induced angiogenesis is mediated via MCPIP. MCPIP deubiquitinated ubiquitinated hypoxia-inducible factor (HIF-1) and the stabilized HIF-1 entered the nucleus to promote the transcription of its target genes, cyclooxygenase-2 and vascular endothelial growth factor causing the activation of p38 MAP kinase involved in angiogenesis. MCPIP expression promoted angiogenesis by inhibition of thrombospondin-1 synthesis via induction of silent information regulator (SIRT)-1 and/or via suppression of VEG-inhibitor levels caused by inhibition of NF-B activation. MCPIP inhibited the production of the anti-angiogenic microRNAs (miR)-20b and miR-34a that repress the translation of HIF-1 and SIRT-1, respectively. Cells expressing the RNasedead mutant of MCPIP, D141N, that had lost the ability to induce angiogenesis had deubiquitinase activity but did not inhibit the production of miR-20b and miR-34a. Mimetics of miR-20b and miR-34a inhibited MCPIP-induced angiogenesis. These results show for the first time that both deubiquitinase and anti-dicer RNase activities of MCPIP are involved in inflammatory angiogenesis. Results from our study delineate key processes that could be potential targets for therapeutic intervention against inflammatory angiogenesis.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21607号 / 理博第4514号 / 新制||理||1648(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)講師 嶋田 知生, 教授 長谷 あきら, 教授 鹿内 利治 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM