Measurement of thermal accommodation coefficients of steel surfaces

The thermal accommodation coefficient plays an important role in low density thermal energy transfer measurement. The object of this investigation was to measure the thermal energy transfer between a heated test surface and a water cooled reference surface (flat black lacquer) consisting of two infinite concentric cylinders separated by dry air. Two machined and sanded steel cylinders with mean surface roughnesses of 25 microinches and 7.5 microinches were used as the test surfaces . Measurements were made in the pressure range of 1.2 x 10⁻⁶ mm Hg. to 1.8 x 10⁻⁶ mm Hg. and temperature range for test cylinders of 110°- 200. 2°F. in determining the emittance. The pressure range was 1.0 x 10⁻³ mm Hg. to 1.35 x 10⁻³ mm Hg. and the temperature range 115.5° -197.6° F. in determining the thermal accommodation coefficients. The thermal accommodation coefficient for dry air on a steel surface with an average mean surface roughness of 25 microinches was 0.835 (emittance was 0.174) while for the 7.5 microinches surface condition, the thermal accommodation coefficient was 0.693 (emittance was 0.123). The experimental data indicated that for the same material, the rougher surface will have a higher value of thermal accommodation coefficient and emittance. The experimental results agree closely with those of classical theory (roughness causes more than one collision at the surface) and with some other investigators (2 & 7). The accuracy of the results as well as the experimental deviations are within the accepted engineering limits for this type of measurement --Abstract, Pages ii-iii

Immune-Mediated Drug Induced Liver Injury: A Multidisciplinary Approach

This thesis presents an approach to expose relationships between immune mediated drug induced liver injury (IMDILI) and the three-dimensional structural features of toxic drug molecules and their metabolites. The series of analyses test the hypothesis that drugs which produce similar patterns of toxicity interact with targets within common toxicological pathways and that activation of the underlying mechanisms depends on structural similarity among toxic molecules. Spontaneous adverse drug reaction (ADR) reports were used to identify cases of IMDILI. Network map tools were used to compare the known and predicted protein interactions with each of the probe drugs to explore the interactions that are common between the drugs. The IMDILI probe set was then used to develop a pharmacophore model which became the starting point for identifying potential toxicity targets for IMDILI. Pharmacophore screening results demonstrated similarities between the probe IMDILI set of drugs and Toll-Like Receptor 7 (TLR7) agonists, suggesting TLR7 as a potential toxicity target. This thesis highlights the potential for multidisciplinary approaches in the study of complex diseases. Such approaches are particularly helpful for rare diseases where little knowledge is available, and may provide key insights into mechanisms of toxicity that cannot be gleaned from a single disciplinary study

Immune-Mediated Drug Induced Liver Injury: A Multidisciplinary Approach

This thesis presents an approach to expose relationships between immune mediated drug induced liver injury (IMDILI) and the three-dimensional structural features of toxic drug molecules and their metabolites. The series of analyses test the hypothesis that drugs which produce similar patterns of toxicity interact with targets within common toxicological pathways and that activation of the underlying mechanisms depends on structural similarity among toxic molecules. Spontaneous adverse drug reaction (ADR) reports were used to identify cases of IMDILI. Network map tools were used to compare the known and predicted protein interactions with each of the probe drugs to explore the interactions that are common between the drugs. The IMDILI probe set was then used to develop a pharmacophore model which became the starting point for identifying potential toxicity targets for IMDILI. Pharmacophore screening results demonstrated similarities between the probe IMDILI set of drugs and Toll-Like Receptor 7 (TLR7) agonists, suggesting TLR7 as a potential toxicity target. This thesis highlights the potential for multidisciplinary approaches in the study of complex diseases. Such approaches are particularly helpful for rare diseases where little knowledge is available, and may provide key insights into mechanisms of toxicity that cannot be gleaned from a single disciplinary study

The effect of aspect ratio on compressor performance

It is shown that the optimum aspect ratio at which max efficiency occurs is relatively low, typically between 1 and 1.5. At these aspect ratios, inaccuracies inherently exist in the decomposition of the flow field into freestream and endwall components due to the absence of a clear freestream. In this paper, a unique approach is taken; McKenzie’s ‘linear repeating stage’ concept is used plus a novel way of defining the freestream flow is proposed. Through this unique approach, physically accurate decomposition of the flow field for aspect ratios as low as ~0.7 can be achieved. This ability to accurately decompose the flow field leads to several key findings. Firstly, the endwall flow is found to be dependent on static pressure rise coefficient and endwall geometry, but independent of aspect ratio. Secondly, the commonly accepted relationship of endwall loss coefficient varying inversely with aspect ratio is physically inaccurate. Instead, a new term, which the authors refer to as ‘effective aspect rati o’, should replace aspect ratio. It is shown that not doing so can result in efficiency errors of ~0.6% at low aspect ratios. Finally, there exists a low aspect ratio limit below which the two endwall flows interact causing a large separation to occur along the span. From these findings, a low order model is developed to model the effect of varying aspect ratio on performance. The last section of the paper uses this low order model as well as a simple analytical model to show that to a first order, the optimum aspect ratio is just a function of the loss generated by the endwalls at zero clearance and the rate of change in profile loss due to blade thickness. This means that once the endwall configuration has been selected i.e. cantilever or shroud, the blade thickness sets the optimum aspect ratio.EPSR

The Effect of Aspect Ratio on Compressor Performance

Abstract The optimum aspect ratio at which maximum efficiency occurs is relatively low, typically between 1 and 1.5. At these aspect ratios, inaccuracies inherently exist in the decomposition of the flow field into freestream and endwall components due to the absence of a discernible freestream. In this paper, a unique approach is taken: a “linear repeating stage” concept is used in conjunction with a novel way of defining the freestream flow. Through this approach, physically accurate decomposition of the flow field for aspect ratios as low as ∼0.5 can be achieved. This ability to accurately decompose the flow leads to several key findings. First, the endwall flow is found to be dependent on static pressure rise coefficient and endwall geometry, but independent of the aspect ratio. Second, the commonly accepted relationship that endwall loss coefficient varies inversely with the aspect ratio is shown to be physically inaccurate. Instead, a new term, which the authors refer to as the “effective aspect ratio,” should replace the term “aspect ratio.” Moreover, not doing so can result in efficiency errors of ∼0.6% at low aspect ratios. Finally, there exists a low aspect ratio limit below which the two endwall flows interact causing a large separation to occur along the span. From these findings, a low-order model is developed to model the effect of varying aspect ratio on compressor performance. The last section of the paper uses this low-order model and a simple analytical model to show that to a first order, the optimum aspect ratio is just a function of the loss generated by the endwalls at zero clearance and the rate of change in profile loss due to blade thickness. This means that once the endwall configuration has been selected, i.e., cantilever or shroud, the blade thickness sets the optimum aspect ratio.</jats:p

Exploring the phase space of multiple states in highly turbulent Taylor-Couette flow

We investigate the existence of multiple turbulent states in highly turbulent Taylor-Couette flow in the range of $\mathrm{Ta}=10^{11}$ to $9\cdot10^{12}$, by measuring the global torques and the local velocities while probing the phase space spanned by the rotation rates of the inner and outer cylinder. The multiple states are found to be very robust and are expected to persist beyond $\mathrm{Ta}=10^{13}$. The rotation ratio is the parameter that most strongly controls the transitions between the flow states; the transitional values only weakly depend on the Taylor number. However, complex paths in the phase space are necessary to unlock the full region of multiple states. Lastly, by mapping the flow structures for various rotation ratios in a Taylor-Couette setup with an equal radius ratio but a larger aspect ratio than before, multiple states were again observed. Here, they are characterized by even richer roll structure phenomena, including, for the first time observed in highly turbulent TC flow, an antisymmetrical roll state.Comment: 9 pages, 7 figure

The Effects of Red Wine and Grape Juice Consumption in Overweight Individuals on Multiple Health Parameters

PURPOSE: To investigate the effects of muscadine red wine and grape juice on weight, body fat, lipids, inflammation, and antioxidant capacity in overweight individuals. METHODS: In a randomized crossover design, 19 subjects consumed 300 mL of wine (WG) or grape juice (JG) for two weeks and acutely upon returning to the lab. Blood was drawn at baseline, post two weeks, and acutely. The statistical design was a 2 (treatments) x 3 (times) repeated measures ANOVA. RESULTS: Overall weight gain occurred in both groups with treatment effect (P=0.044) and time effect (P=0.018). Significant weight gain was found in WG (P=0.027). Total fat mass percentage, C-reactive protein and lipids were not affected by red wine or grape juice consumption. Ferric reducing ability of plasma significantly increased after acute, but not chronic, consumption of red wine (P&lt;0.001). Oxygen radical absorptive capacity of plasma did not change significantly for either treatment. CONCLUSION: Adding wine or grape juice to the diets of overweight sedentary individuals, with no other dietary alterations, resulted in significant weight gain. Acute consumption of red wine resulted in significant changes in antioxidant capacity which may confer potential benefits on health variables other than ones examined in the present study

Awareness, knowledge and attitude on cleft lip and palate among antenatal clinic attendees of tertiary hospitals in Nigeria

Background: Adequate knowledge and awareness of cleft lip and palate (CLP) deformity may help to counter the negative beliefs and attitudes toward the condition. The objective of this study was to assess the level of awareness, knowledge and attitude of women attending antenatal clinics about CLP.Materials and Methods: A cross‑sectional descriptive study with the aid of a structured interview administered questionnaire was conducted among 200 women attending antenatal clinics in three Federal Government Teaching Hospitals in the Northern and Southwestern regions of Nigeria. The main outcome measure was the level of awareness and the mean cumulative knowledge score.Results: The mean age of the subjects was 28.9 ± 5.1 years (age range: 16‑42 years). Half of the women (50.5%) reported that they had seen or heard about CLP. The mean cumulative knowledge score was 6.9, with only 19.8% having adequate knowledge. Many respondents had neither read an article on CLP nor participated in any public enlightenment program, and 31.5% indicated that they would like to know more about the condition. Level of educational attainment had a statistically significant effect on the level of awareness and knowledge on CLP, as more educated respondents tend to be more aware and knowledgeable (P &lt; 0.001).Conclusion: There is need for increased public enlightenment/health education to increase awareness and subsequently help develop more positive attitudes toward children with CLP. Such programs should include distribution of pamphlets on CLP at clinics, especially antenatal clinics, media campaigns on radio, TV and newspaper as well as establishment of cleft support groups by the relevant governmental and professional organizations.Key words: Antenatal clinics, awareness, cleft lip, knowledge, pregnant wome

Effect of Hydrogen Peroxide and Superoxide Anions on Cytosolic Ca2+: Comparison of Endothelial Cells from Large-Sized and Small-Sized Arteries

We compared the Ca2+ responses to reactive oxygen species (ROS) between mouse endothelial cells derived from large-sized arteries, aortas (aortic ECs), and small-sized arteries, mesenteric arteries (MAECs). Application of hydrogen peroxide (H2O2) caused an increase in cytosolic Ca2+ levels ([Ca2+]i) in both cell types. The [Ca2+]i rises diminished in the presence of U73122, a phospholipase C inhibitor, or Xestospongin C (XeC), an inhibitor for inositol-1,4,5-trisphosphate (IP3) receptors. Removal of Ca2+ from the bath also decreased the [Ca2+]i rises in response to H2O2. In addition, treatment of endothelial cells with H2O2 reduced the [Ca2+]i responses to subsequent challenge of ATP. The decreased [Ca2+]i responses to ATP were resulted from a pre-depletion of intracellular Ca2+ stores by H2O2. Interestingly, we also found that Ca2+ store depletion was more sensitive to H2O2 treatment in endothelial cells of mesenteric arteries than those of aortas. Hypoxanthine-xanthine oxidase (HX-XO) was also found to induce [Ca2+]i rises in both types of endothelial cells, the effect of which was mediated by superoxide anions and H2O2 but not by hydroxyl radical. H2O2 contribution in HX-XO-induced [Ca2+]i rises were more significant in endothelial cells from mesenteric arteries than those from aortas. In summary, H2O2 could induce store Ca2+ release via phospholipase C-IP3 pathway in endothelial cells. Resultant emptying of intracellular Ca2+ stores contributed to the reduced [Ca2+]i responses to subsequent ATP challenge. The [Ca2+]i responses were more sensitive to H2O2 in endothelial cells of small-sized arteries than those of large-sized arteries