MODELLING, CHARACTERISATION AND INTERPRETATION OF RHEOLOGICAL EXPERIMENTS PERFROMED ON AQUEOUS SOLUTIONS OF WORM LIKE MICELLES

This thesis reports a series of theoretical, experimental and computational investigations concerning advanced rheometry and the dynamics of worm like micellular systems (WLMs) in superposition rheometry. A robust experimental data set is first obtained under both parallel and orthogonal superposition rheometry conditions before the ability of the Corotational Maxwell, Giesekus and, for the first time, Gordon-Schowolter constitutive models to capture the behaviour of WLMs under superposition flows is evaluated. The initiation of stress controlled oscillatory rheometry is then investigated both theoretically and experimentally (using the same WLM system) to determine the impact of instrument inertia on the establishment of steady state oscillatory flows. This study reveals that the time scale for the establishment of steady state oscillations can be dramatically impacted by the presence of instrument inertia. Finally, a Brownian Dynamics approach is used in an attempt to identify the polymer dynamics responsible for the appearance of negative values of the ‘parallel storage modulus’ under certain conditions, as is often noted in the literature

The Gordon–Schowalter/Johnson–Segalman model in parallel and orthogonal superposition rheometry and its application in the study of worm-like micellular systems

Parallel and Orthogonal Superposition experiments may be employed to probe a material’s non-linear rheological properties through the rate-dependent parallel and orthogonal superposition moduli, G∗ ∥(ω, γ˙ ) and G∗ ⊥(ω, γ˙ ), respectively. In a recent series of publications, we have considered the problem of interconversion between parallel and orthogonal superposition moduli as a means of probing flow induced anisotropy. However, as noted by Yamomoto in 1971 [Yamomoto, Trans. Soc. Rheol 15 (1971) 331-344]] superposition flows may be used to assess the ability of a particular constitutive model to describe the flow of complex fluids. Herein, we derive expressions for the superposition moduli of the Gordon-Schowalter (or Johnson-Segalman) fluid. This model contains, as special cases, the corotational Maxwell model, the upper (and lower) convected Maxwell models, the corotational Jeffreys model, and the Oldroyd-B model. We also consider the conditionsunder which the superposition moduli may take negative values before studying a specific, non shear banding, worm like micellular system of cetylpyridinium chloride and sodium salicylate. We find that, using a weakly non-linear analysis (in which the model parameters are rate independent) the Gordon-Schowalter/Johnson- Segalman (GS/JS) model is unable to describe the superposition moduli. However, by permitting strong non-linearity (allowing the GS/JS parameters to become shear rate dependent), the superposition moduli, at all rates studied, are described well by the model. Based on this strongly non-linear anlaysis, the shear rate dependency of the GS/JS ‘slip parameter’, a, suggests that the onset of shear thinning in the specific worm-like micellular system studied herein is driven by a combination of microstructural modification and a transition from rotation dominated (as in the corotational Jeffreys model) to shear dominated (as in the Oldroyd-B model) deformation of the microstructural elements

Peer Accusations of Acting White: Longitudinal Effects on Minority Adolescents' Ethnic Identity and Depressive Symptoms

The “acting white” (AW) accusation is an insult directed at minority adolescents for appearing to conform to norms associated with white society. Although the term was first introduced in the 1980’s, by John Ogbu and Signithia Fordham, as part of a theory on the increasing achievement gap between white students and their minority peers, few studies have examined how the AW accusation affects minority students psychologically. Data were collected from a sample of minority high school students (N=173), over four years, at three diverse high schools in rural North Carolina. There are two major aims in this study. First, this study seeks to identify and describe the characteristics of students who are accused of AW. Second, this study explores the longitudinal effects of the accusation, specifically with regard to ethnic identity and depressive symptoms. Results indicated that students who are accused of AW are more likely to be made fun of for they way that they speak, experience higher levels of social anxiety, and be more popular among their white peers. Longitudinally, students who reported stressful experiences with the AW accusation reported lower levels of ethnic identity and higher levels of depressive symptoms. The findings from this study suggest that the AW accusation may negatively affect the psychological adjustment of minority adolescents. Future research should further examine how the AW accusation is linked to negative mental health outcomes.Bachelor of Art

Thyroid hormone: a “prime suspect” in human immuno deficiency virus (hiv/aids) patients?

Acquired Immunodeficiency Syndrome (AIDS) is the final and most serious stage of the disease caused by human immunodeficiency virus. The Immune system is the target of AIDS. We investigate presentlyany possible involvement of thyroid hormone, the deficiency of which gives rise to oedema and susceptibility to nonspecific infections; with a view to finding the primary factor seeding the disease. It has been reported that circumcision reduced the incidence of HIV/AIDS infection. Beyond circumcision however there might be someconstitutional factor that comprises HIV infection to clinical AIDS. It is against this background that our research team turned to possible dyshormonopoisis and to thyroid hormone as a prime suspect among other possible factors that cause clinical AIDS. Moreover the hormone has been reported to be crucial for optimum immune function. A population of 200 seropositive AIDS patients were investigated against a control of 50 subjects made up of 25 healthy circumcised males and 25 healthy females; all of who were seronegative for the disease. The parameters investigated include thyrotropin (TSH), Thyroxine (T4), Total protein (TP), Albumin (Alb), Globulin (Glob), Immune complex (IC3) and Bence Jones proteins (BJP) levels in serum or urine. All seropositive clinically HIV/AIDS patients were hypothyroid. Seronegatives had significantly higher T4, TP, and Alb levels at

The Relationship of Gamma Immunoglobin (IgG) Density and Apgar Score in Normal Term Pregnancy

The transfer of maternal IgG provides the neonate with humoral immunity during early life. The population of transferred IgG or IgG density (IgGρ) was estimated to find out if it has any relevance to the condition of an infant 1-5 minutes after birth or APGAR score which gives an insight into the state of health of the infant and thus its chances of survival and its milestone of development. Ex-vivo, term placenta of forty euthyroid mothers, the maternal serum, and cord blood were used to estimate the IgGρ in both maternal and cord blood by taking blood samples from the antecubital vein of the mother and from the umbilical cord (mixed blood) immediately after birth; having determined the APGAR score within 1-5 minutes post-partum. The findings featured the following: the mean APGAR score (10); mean IgGρ of the neonates (11.94 ± 0.12mg/100ml of blood); mean IgGρ of the maternal blood (10.9 ± 0.29/100ml). The difference however, was not statistically significant (P>0.05). The findings provide evidence suggesting that IgGρ, not only relates to, but determines APGAR score of the neonates.Keywords: APGAR score, IgG density, Term placenta, Cord bloo

The Influence of Thyroid Hormones on Gamma Immunoglobulin Density (Ig-Gp) and Apgar Score

Observations over the years, particularly in the labour rooms of Jos University Teaching Hospital (JUTH), and TANDAM Medical Centre, Jos, Plateau, Nigeria, indicates that several neonates respond differently to these parameters. However, the experience of four mothers who had protracted labour and neonates with weak cry and low muscle tone, prompted this present investigation. Ex-vivo placenta, maternal and cord blood of twenty deliveries (10 primipara and ten multipara; five of which were by elective caesarean section) were assayed for thyroid hormone in maternal serum and IgGp in maternal and cord sera; while the APGAR scores of the neonates were as well, documented. Results showed that the mean immunoglobulin G population (IgGp) or density of neonates compared with that of their euthyriod mothers though higher in neonates was not statistically significant (P> 0.05). It was however significant (p < 0.01) between neonates and their hypothyroid mothers. APGAR score of the neonates of the euthyroid mothers were higher (p < 0.05) than those hypothyroid mothers who also bled for longer periods postpartum. It is our opinion that there could perhaps be an insight into the cause of such agonizing deliveries and to that effect, we recommended possible interventions.Keywords: Euthyroidism, hypothyroidism, APGAR score, Gamma Immunoglobulin (IgG

Butyrylcholinesterase as a prognostic marker: a review of the literature.

BACKGROUND: Butyrylcholinesterase (BChE) is an α-glycoprotein synthesized in the liver. Its serum level decreases in many clinical conditions such as acute and chronic liver damage, inflammation, injury and infections, and malnutrition. METHODS AND RESULTS: This review collects the main evidence on the emerging role of butyrylcholinesterase as a prognostic marker of liver and nonliver diseases as well as a marker of protein-energy malnutrition and obesity. In fact, serum concentrations and BChE activity seem to accurately reflect the availability of amino acidic substrates and/or derangement in protein synthesis due to hepatocellular damage. In cancer, with or without liver impairment, serum BChE levels serve as an accurate functional and prognostic indicator, useful for monitoring clinical and therapeutic interventions according to patients’ prognosis. In the absence of inflammation, BChE could also serve as an index of the effectiveness of nutritional support. CONCLUSIONS: Serum BChE assessment should be included in routine clinical diagnostic procedures to evaluate patient clinical conditions, in particular in cases of inflammation and/or protein-energy malnutrition

Gertrude Chinwe Ogunkeye oral history interview

Oral history interview with Gertrude Chinwe Ogunkeye, a survivor of the Asaba Massacre, a mass killing of civilians which occurred in 1967 during the Nigerian Civil War. Ogunkeye, her mother, and her siblings were living in Enugu but left shortly after Biafra seceded from Nigeria; they returned home to Asaba, where they stayed with Ogunkeye\u27s grandfather. When the Nigerian soldiers arrived in Asaba, they ordered her family to leave their house and they complied, except for Ogunkeye\u27s uncle, who hid and was later killed. They were taken to the town square, where Ogunkeye saw the soldiers kill two young men and heard machine guns as others were shot. The women, children, and elders were taken by bus to a nearby village, where they stayed for several months until her father, who was living in Lagos, managed to find them. The family did not return to Asaba until after the war was over. Ogunkeye was one of the speakers at the Oputa Panel, the commission which investigated the massacre. In this interview, she also comments on the conflict\u27s causes and emphasizes the need for a memorial