Experimental and theoretical performance evaluation of parabolic trough mirror as solar thermal concentrator to thermoelectric generators

This paper presents the prospects of harnessing radiative heat from the sun with a parabolic trough mirror, as a solar thermal concentrator, in comparison to the mathematical model and experimental quartz-halogen concentrator model for the electrical energy conversion utilizing thermoelectric generators (TEG). The construction and design of TEG-setup along with Parabolic trough mirrors and quartz-halogen lamps are presented. The Parabolic trough mirror used as a focal point at a distance of 19.05 cm. With eight quartz-halogen concentrated heat, the maximum performance achieved at ΔT of 11.8 K, Voc of 292 mV and Isc of 95.8 mA, recorded at the concentrated hot-side surface temperature of 317.8 K. When compared to the natural solar concentrated heat, higher temperature of 473.15 K at the hot-side surface temperature of TG was achieved. It is concluded that the heat concentration of the parabolic mirror increases with an increase in the intensity of heat using natural solar radiations. The Voc of 1.76 V and Isc of 1.1 A at a temperature difference of 110 K were measured, which are in good agreement with validated mathematical results. The parabolic through mirror utilized is smaller in size and thus collected lesser sun rays than the larger dish style mirror, and hence the heat in the focal point was very low, for better results, parabolic trough mirror with higher surface area would be important for future experiments

Seroprevalence of Brucellosis, Knowledge, and Risky Practices in Dairy Cattle Owners and Workers in Maekel and Debub Regions, Eritrea.

Brucellosis is a zoonotic disease with worldwide distribution. In Eritrea, the status of the disease in occupationally exposed dairy farmers is unknown. The objective of this study was to determine the seroprevalence of brucellosis, level of knowledge, and risky practices of dairy cattle owners/workers in Maekel and Debub regions, Eritrea. A cross-sectional study was conducted between August 2021 and February 2022. A total of 416 dairy cattle owners and workers underwent blood collection and interview using a standardized questionnaire. Blood samples were tested using Rose Bengal Plate Test, and positive samples were confirmed using competitive ELISA. Variation in knowledge scores by sociodemographic factors and practices were explored statistically. The apparent and true seroprevalence was 1.2% (95% CI: 0.05-2.8%) and 1.4% (95% CI: 0.6-3.4%), respectively. Apparent seroprevalence was similar in Maekel (1.1%) and Debub (1.2%) regions. Nearly half of the participants (49.5%) had never heard of brucellosis before. Overall, brucellosis knowledge score was low (mean score: 6.53/20). Knowledge score was higher in participants from Maekel region (P <0.001), older participants (P = 0.035), those with higher educational attainment (P = 0.001), and those with more years of experience working in dairy farming (P = 0.001). Knowledge score was lower in farm workers compared with family members (P = 0.016). No significant differences in knowledge score existed between participants who engaged in or did not engage in potential risky practices. In summary, the prevalence of brucellosis in dairy cattle owners/workers in Maekel and Debub regions, Eritrea, was low. Participants demonstrated limited knowledge of brucellosis and engaged in risky practices

Prevalence of brucellosis and associated risk factors in dairy cattle in Maekel and Debub Regions, Eritrea

IntroductionBrucellosis is a zoonotic disease with worldwide distribution. It is considered endemic in Eritrea, however, the current prevalence status and related risk factors in animals are unknown. The objective of this study was to determine the prevalence of and risk factors for brucellosis in dairy cattle in Maekel and Debub regions, Eritrea.MethodsA cross sectional study was conducted between August 2021 and February 2022. A total of 2,740 dairy cattle from 214 herds in 10 sub-regions of Eritrea were selected for blood and data collection. Blood samples were tested using Rose Bengal Plate Test (RBPT) and positive samples were confirmed using competitive (c-ELISA). Data on risk factors was collected using questionnaire and analyzed using logistic regression.ResultsIn total, 34/2740 animals tested positive by RBPT. Of these, 29 were confirmed positive by c-ELISA, giving an apparent and estimated true individual-level prevalence of 1.1% (95% CI: 0.7, 1.5%) and 1.3% (95% CI: 0.9, 1.8%), respectively. Sixteen herds (7.5%) tested positive by RBPT and of these 15 herds (7.0%) were confirmed positive by c-ELISA, giving an estimated true herd-level prevalence of 7.0% (95% CI: 4.0, 10.7). Animal and herd-level apparent prevalence was 1.6 and 9.2% in Maekel, while in Debub it was 0.6 and 5.5%, respectively. Multivariable regression analysis indicated that non-pregnant lactating cows (adjusted odds ratio [aOR] = 3.35; p = 0.042) were more likely to be Brucella sero-positive. History of abortion on the farm (aOR = 5.71; p = 0.026) and larger number of cows in the herd (aOR = 1.14; p &amp;lt; 0.001) were associated with brucellosis sero-positivity in herds.ConclusionBrucellosis prevalence was low in the study areas. Nonetheless, this low prevalence may increase if the disease is not controlled. Therefore, testing animals before movement, good farming practices, sanitary measures, and an awareness raising program on brucellosis are recommended.</jats:sec