Analytical Modeling of a Novel Elastohydrodynamic Seal Design for Supercritical CO2 Power Cycles

Supercritical carbon dioxide (sCO2) power cycles show great potential for higher plant efficiencies and power densities for a wide range of power generation applications such as fossil fuel power plants, nuclear power production, solar power, and geothermal power generation. sCO2 leakage has been one of the main concerns in such applications, penalizing the cycle efficiencies. The effect of the seal leakage on the cycle efficiency could be as high as 0.65% for a utility sCO2 power cycle. Therefore, there is a pressing need for effective sealing solutions to get the full benefit of sCO2 power generation technology. To offer a potential solution, we propose an Elasto-Hydrodynamic (EHD) seal that can work at elevated pressures and temperatures with low leakage and minimal wear. The EHD seal has a very simple, sleeve like structure, wrapping on the rotor with minimal initial clearance at 25 to 50µm levels. In this work, a proof-of-concept study for the proposed EHD seal was presented by using the Reynolds equation, Lame’s formula, Barus Equation, and Dowson-Higginson formula to model the pressure distribution along the seal clearance as well as the seal deformation. The analytical modeling of the seal was carried out in MATLAB using its built-in ordinary differential equation solver. The seal was evaluated for a 2” diameter test seal with a pressure range of 0.2MPa to 20MPa. At the high pressure of 20MPa, the clearance height at the throat (ht) was found to be 24.7µm which is about 50.6% than the initial seal clearance (h0) of 50µm, which resulted in a mass flow rate of 0.00162 kg/s. Also, a parametric study was conducted to see the effects of the seal thickness, shaft diameter, and seal length on the performance of the seal. The results showed that all three geometric parameters play a major role in the seal deformation and the mass flow rate of the seal. For the seal thickness, the mass flow rate increased as the seal thickness increased. It resulted to be 0.00161 kg/s and 0.004055kg/s for seal thickness 0.5mm and 2.0mm, respectively at 20MPa. An increase in the shaft diameter led to a decrease in mass flow rate with 0.00187 kg/s and 0.00125 kg/s for 25mm and 50mm respectively at 20MPa. For the seal length, the mass flow rate decreased with increasing seal length with 0.00255 kg/s and 0.001185 kg/s for seal lengths of 13mm and 28mm respectively at 20MPa. The presented analytical study lays a solid foundation for future model developments that could be used in the design of the proposed EHD seal

Distribution of Lead and Cadmium in Soils on Koko Seaport, Delta State, Nigeria

Soil contamination by Lead and Cadmium is a prevalent ecological problem that requires attention because these two metals are toxic and could accumulate and translocate in soil over time, which poses a risk of entering the food chain and affecting the living organisms in the food web. The objective of this study is to evaluate the levels of Pb and Cd in soil from selected sampling locations of the Koko Seaport in Delta State, Nigeria. Five areas near Koko Seaport were investigated for the transport of these heavy metals in the soil. Statistical analysis using ANOVA and chart models was used to determine the concentration of these metals. Cadmium and lead levels that were significant were found in the studied areas. The data did not show any differences between the two metals due to the significance of the *p>0.05 value. The variations showed a surge in comparisons of the amounts of cadmium in stations 2 and 3, respectively, as well as significant values for cadmium compared to lead. The outcome was directly influenced by the type and quantity of hazardous wastes present in the research area. The recommended remedial actions for these metals include soil cleansing, immobilization, and the choice of plants with hyper bio accumulation for phytoremediation methods that allow the use of genetic engineering

Effects of Household Waste Generation, Disposal and Management on Farmers’ Health in Owerri Metropolis of IMO State, Nigeria

The study investigated the effects of household waste generation, disposal and management on farmers' health in Owerri metropolis. It specifically ascertained the socio-economic characteristics of the farmers, identified the types and sources of waste in the study area, examined the waste disposal and management methods in the study area examined the effects of inappropriate waste disposal and ascertained the appropriate waste disposal methods used in the study area. A multi stage sampling technique was used to select one hundred and eight farmers from the three Local Government Area in Owerri metropolis. Data were collected using a validated questionnaire and were analyzed using descriptive statistics tool such as mean, frequency, percentage, and mean scores. Results show that waste is majorly generated from markets and residential homes. Waste disposal methods were mainly burning, landfills and open dumping. Its effects includes destroys the beauty of the environment, blocks gutters and drainage system, pollutes the environment among others. Subsequently, appropriate waste disposal methods in the study area includes burning of waste (29.17%), placing of bins at appropriate places (16.07%). The study recommends amongst others that waste management environmental agency should make waste dumps or receptacles accessible to residents, public campaigns should be embarked upon to educate the citizens on ills of dirty environment

Recruitment and Retention Strategies for Minority or Poor Clinical Research Participants: Lessons From the Healthy Aging in Neighborhoods of Diversity Across the Life Span Study

PURPOSE OF THE STUDY: Investigating health disparities requires studies designed to recruit and retain racially and socioeconomically diverse cohorts. It is critical to address the barriers that disproportionately affect participation in clinical research by minorities and the socioeconomically disadvantaged. This study sought to identify and rectify these barriers to recruit and retain a biracial (African American and non-Hispanic White) and socioeconomically diverse cohort for a longitudinal study. DESIGN AND METHOD: The Healthy Aging in Neighborhoods of Diversity across the Life Span study is a 20-year longitudinal examination of how race and socioeconomic status influence the development of age-related health disparities. One goal was to create a multifactorial recruitment and retention strategy. The recruitment paradigm targeted known barriers and identified those unique to the study's urban environment. The retention paradigm mirrored the recruitment plan but was based on specifically developed approaches. RESULTS: This cohort recruitment required attention to developing community partnerships, designing the research study to meet the study hypotheses and to provide benefit to participants, providing a safe community-based site for the research and creating didactics to develop staff cultural proficiency. These efforts facilitated study implementation and enhanced recruitment resulting in accrual of a biracial and socioeconomically diverse cohort of 3,722 participants. IMPLICATIONS: Recruiting and retaining minority or poor research participants is challenging but possible. The essential facets include clear communication of the research hypothesis, focus on providing a direct benefit for participants, and selection of a hypothesis that is directly relevant to the community studied.http://dx.doi.org/10.1093/geront/gnr02

Jungle Honey Enhances Immune Function and Antitumor Activity

Jungle honey (JH) is collected from timber and blossom by wild honey bees that live in the tropical forest of Nigeria. JH is used as a traditional medicine for colds, skin inflammation and burn wounds as well as general health care. However, the effects of JH on immune functions are not clearly known. Therefore, we investigated the effects of JH on immune functions and antitumor activity in mice. Female C57BL/6 mice were injected with JH (1 mg/mouse/day, seven times intra-peritoneal). After seven injections, peritoneal cells (PC) were obtained. Antitumor activity was assessed by growth of Lewis Lung Carcinoma/2 (LL/2) cells. PC numbers were increased in JH-injected mice compared to control mice. In Dot Plot analysis by FACS, a new cell population appeared in JH-injected mice. The percent of Gr-1 surface antigen and the intensity of Gr-1 antigen expression of PC were increased in JH-injected mice. The new cell population was neutrophils. JH possessed chemotactic activity for neutrophils. Tumor incidence and weight were decreased in JH-injected mice. The ratio of reactive oxygen species (ROS) producing cells was increased in JH-injected mice. The effective component in JH was fractionized by gel filtration using HPLC and had an approximate molecular weight (MW) of 261. These results suggest that neutrophils induced by JH possess potent antitumor activity mediated by ROS and the effective immune component of JH is substrate of MW 261

High-Frequency Ultrasound Imaging of the Intestine in Normal Subjects and Patients with Intestinal Parasites

High-frequency ultrasound imaging was used to evaluate the intestinal walls of the duodenum and colon in patients with intestinal parasitic infections. Ultrasound images were obtained from 100 consecutive patients with symptomatic intestinal parasitic diseases and 40 healthy controls. High-frequency annular array transducer of 7.5 MHz was used to obtain B-mode ultrasound gray-scale and color images of the duodenum and colon with and without water contrast. The diagnosis of parasitic infections was based on clinical presentation, serial stool microscopy, and finding of parasites in duodenal aspirates. We demonstrated normal duodenum and colon echoanatomy in control subjects. In patients with giardiasis, the lesions of the duodenum and colon were associated with increased dimensions and wall thickness compared to healthy controls (p < 0.05). The ultrasound features of giardial lesions were characterized by increased wall echogenicity, flattening or loss of duodenal folds, and/or colonic haustration, hyperechoic floating foci demonstrating chaotic motility, increased perilesional tissue echogenicity, and altered colonic peristalsis. In amebic lesions there were hyperechoic floating foci with bulk motility. There is loss of wall thickness at amebic ulcer sites or wall thickening at amebic granuloma. Helminths were visualized as large hyperechoic linear or curvilinear foci with serpentine or jolting motility. In conclusion, high-frequency B-mode ultrasound imaging with water contrast demonstrated details of duodenal and colonic echoanatomy in normal subjects and patients with giardiasis

Perceived Role of Agricultural Extension Services in Promoting Cooperative Entrepreneurship among Farmers in Ahiazu Mbaise Local Government Area, IMO State

Cooperative entrepreneurship avails participating entrepreneurs the opportunity to combine different skills and competencies to set up an enterprise. This study assessed the perceived roles of agricultural extension services in promoting cooperative entrepreneurship among farmers in Ahiazu Mbaise Local Government Area, Imo State. Data was collected from 120 respondents with the aid of a well-structured questionnaire. Results revealed that farmers in the study area were engaged in different entrepreneurial activities. They perceived the roles of agricultural extension services as effective in promoting cooperative entrepreneurship with the provision of vocational/skill training; sanitation activities; provision of storage/processing facilities; procurement of agricultural input and information on credit sources. The perceived constraints militating against extension service delivery to the respondents were inadequate finding; lack of technical support and poor infrastructure in communities. It was recommended that government and non-governmental organizations should provide adequate funding and technical support to extension personnel to enable them deliver agricultural extension services geared at promoting cooperative entrepreneurship to farmers

Gender and Resource Productivity in Rice Production n Ebonyi State, Nigeria

Abstract: The inadequacy of information on resource productivity and their differentials by gender in rice production has prevented rice farmers from knowing the resources they are yet to realize their full potentials. This study analyzed resource productivity by gender in rice production in Ebonyi State of Nigeria. Multi-stage random sampling techniques were used to select a sample of 130 rice farmers comprised of 65 males and 65 females from the 13 Local government areas of Ebonyi State. Data were collected with structured and validated questionnaire and analyzed using descriptive statistics and productivity model. Results showed that marginal productivity of labour, capital and land for male farmers were higher than those of female farmers, while the marginal productivity of fertilizer and seed for female farmers were higher than those of male farmers. Rice farmers should be encouraged to use more of the resource imputs since a unit change in their use increases rice output

Recruitment and Retention Strategies for Minority or Poor Clinical Research Participants: Lessons From the Healthy Aging in Neighborhoods of Diversity Across the Life Span Study

Purpose of the study: Investigating health disparities requires studies designed to recruit and retain racially and socioeconomically diverse cohorts. It is critical to address the barriers that disproportionately affect participation in clinical research by minorities and the socioeconomically disadvantaged. This study sought to identify and rectify these barriers to recruit and retain a biracial (African American and non-Hispanic White) and socioeconomically diverse cohort for a longitudinal study. Design and Method: The Healthy Aging in Neighborhoods of Diversity across the Life Span study is a 20-year longitudinal examination of how race and socioeconomic status influence the development of age-related health disparities. One goal was to create a multifactorial recruitment and retention strategy. The recruitment paradigm targeted known barriers and identified those unique to the study's urban environment. The retention paradigm mirrored the recruitment plan but was based on specifically developed approaches. Results: This cohort recruitment required attention to developing community partnerships, designing the research study to meet the study hypotheses and to provide benefit to participants, providing a safe community-based site for the research and creating didactics to develop staff cultural proficiency. These efforts facilitated study implementation and enhanced recruitment resulting in accrual of a biracial and socioeconomically diverse cohort of 3,722 participants. Implications: Recruiting and retaining minority or poor research participants is challenging but possible. The essential facets include clear communication of the research hypothesis, focus on providing a direct benefit for participants, and selection of a hypothesis that is directly relevant to the community studie

Cluster randomized trial assessing the effects of rapid ethical assessment on informed consent comprehension in a low-resource setting

Background Maximizing comprehension is a major challenge for informed consent processes in low-literacy and resource-limited settings. Application of rapid qualitative assessments to improve the informed consent process is increasingly considered useful. This study assessed the effects of Rapid Ethical Assessment (REA) on comprehension, retention and quality of the informed consent process. Methods A cluster randomized trial was conducted among participants of HPV sero-prevalence study in two districts of Northern Ethiopia, in 2013. A total of 300 study participants, 150 in the intervention and 150 in the control group, were included in the study. For the intervention group, the informed consent process was designed with further revisions based on REA findings. Informed consent comprehension levels and quality of the consent process were measured using the Modular Informed Consent Comprehension Assessment (MICCA) and Quality of Informed Consent (QuIC) process assessment tools, respectively. Result Study recruitment rates were 88.7 % and 80.7 % (p = 0.05), while study retention rates were 85.7 % and 70.3 % (p < 0.005) for the intervention and control groups respectively. Overall, the mean informed consent comprehension scores for the intervention and control groups were 73.1 % and 45.2 %, respectively, with a mean difference in comprehension score of 27.9 % (95 % CI 24.0 % - 33.4 %; p < 0.001,). Mean scores for quality of informed consent for the intervention and control groups were 89.1 % and 78.5 %, respectively, with a mean difference of 10.5 % (95 % CI 6.8 -14.2 %; p < 0.001). Conclusion Levels of informed consent comprehension, quality of the consent process, study recruitment and retention rates were significantly improved in the intervention group. We recommend REA as a potential modality to improve informed consent comprehension and quality of informed consent process in low resource settings