LINEAR PROGRAMMING APPROACH TO MODELING FOUNDRY CUPOLA FURNACE CHARGE

In order to control the specifications of the cast iron produced by the cupola furnace, it is necessary to estimate the proportions of the contents of the furnace charge. Traditionally, knowing the percentage of elements present in each constituent of charge and the loss or gain of each element, the final analysis of cast iron can be estimated by trial and error approach - a common approach in most Nigerian foundry workshops. This study presents a programming model technique used to obtain the optimum cupola furnace charge. The objective function was to minimize total cost of raw material and processing costs. The model was developed and implemented using the hypothetical process data of a Foundry workshop. The model was analysed using MATLAB Software Version 7.0. The results obtained using the model is significantly superior to the conventional trial and error approach. It is faster and brings about satisfying a lot of requests at the most minimal expense.&nbsp

Investigations on the Material Efficacy of Failed Helical Gears in a Gear Train

An investigation on the material efficacy of failed helical gears in the gearbox of an automobile has been carried out. Two helical gear samples taken as representatives of the whole of six in the gearbox were denoted as samples A and B. Methods employed in the failure investigation include visual examination with the unaided eye and fractography; compositional analysis; hardness measurements and microstructural analysis. The results obtained showed that Gear sample A failed by oxidative wear essentially caused by insufficient lubrication. On the other hand, Sample B exhibited no outward sign of failure. Processes culminating in the formation of a wear particle were however noticed few micrometers below the surface of Gear Sample B. Furthermore, in the absence of sufficient lubrication, numerous carbide precipitates formed in both samples contributed to wear of the gear material. It was concluded that the premature service failures of the gears was caused by inadequate lubrication and not inadequate material selection. Keywords: material efficacy; helical gear; wear; lubricatio

Phenological Studies of Two Varieties of Hibiscus cannabinus Linn in Ile-Ife, South West, Nigeria

The phenological study of the flowering, fruiting, foliage and girth changes in two varieties of Hibiscus cannabinus L. with the aim of relating these stages to their different morphological characters. Seeds of the varieties identified as variety A and variety B were planted in different petridishes, they were later thinned downed to five stands and finally planted in medium sized buckets. The time, duration and frequency of leafing, flowering, fruiting, were tracked weekly from the germination period until maturity. The two varieties are different in phenology and can be cultivated for different purposes; the different morphological characters might be under endogenous control. Leaf production is more rapid in Variety B than in variety A hence variety B is recommended for cultivation where numerous, broad and matured leaves are needed. The cultivation of variety B that flowers almost every day of the week is recommended for farmers who wish to make use of the flower and/or fruit production of the plant. Variety A is encouraged for people who need the purple dye for beautifying faces. Keywords: Phenology, Hibiscus, flowering, fruiting, foliage, girth

Coronavirus survey; a bibliometric analysis from 2012-2019

Background: Coronaviruses have emerged from animal reservoirs over the past decades to create severe illness and death. They are the SARS-CoV, MERS-CoV and more recently, the SARS-CoV2. This study is focused at assessing the characteristics of published works involving SARS-CoV and MERS-CoV at global level; using bibliometric analysis. Methods: Peer-reviewed publications were retrieved from the Scopus database between 2012 and 2019. Data were analyzed in terms of the year, journal and number of publications, international collaboration patterns, research institutes, impact factor, h-index and number of times cited. Visual presentation and analysis of the data were performed using RStudio, Tableau and Microsoft Excel. Results: A total of 1707 research publications were published across the world between 2012 and 2019 with the highest and lowest number of publications in 2016 (288) and 2012 (87). USA had 249 articles, followed by South Korea (186) and Saudi Arabia (111). The total number of citations achieved was 39,094 with Journal of Virology (133) had the highest number of published articles, followed by Emerging Infectious Disease (85) and PLOS One (60). Conclusion: This research showed the international diversity of MERS-CoV and SARS-CoV research with 106 countries. It is also not surprising that United States leads in the number of publications, authors and citations because of its global power and economic strength; this can also be said with the other top countries. Saudi Arabia was among the top rank because of the origination of the MERS-CoV in the middle east

Impacts of rainfall and temperature on photoperiod insensitive sorghum cultivar : model evaluation and sensitivity analysis

A combination of local-scale climate and crop simulation model were used to investigate the impacts of change in temperature and rainfall on photoperiod insensitive sorghum in the Sudanian zone of Mali. In this study, the response of temperature and rainfall to yield patterns of photoperiod insensitive sorghum (Sorghum bicolor L. Moench) using the Agricultural Production Systems Simulator (APSIM) model was evaluated. Following model calibration of the cultivar at varying sowing dates over two growing seasons (2013 and 2014), a long-term simulation was run using historical weather data (1981-2010) to determine the impacts of temperature and rainfall on grain yield, total biomass and water use efficiency at varying nitrogen fertilizer applications. The results showed that model performance was excellent with the lowest mean bias error (MBE) of -2.2 days for flowering and 1.4 days for physiological maturity. Total biomass and grain yield were satisfactorily reproduced, indicating fairly low RMSE values of 21.3% for total biomass and very low RMSE of 11.2 % for grain yield of the observed mean. Simulations at varying Nfertilizer application rate with increased temperature of 2 °C, 4 °C and 6 °C and decreased rainfall by 25 and 50 % (W-25% and W-50%) posed a highly significant risk to low yield compared to increase in rainfall. However, the magnitude of temperature changes showed a decline in grain yield by 10%, while a decrease in rainfall by W-25% and W-50% resulted in yield decline between 5% and 37%, respectively. Thus, climate-smart site-specific utilization of the photoperiod insensitive sorghum cultivar suggests more resilient and productive farming systems for sorghum in semi-arid regions of Mali

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Investigations on the Material Efficacy of Failed Helical Gears in a Gear Train

Abstract An investigation on the material efficacy of failed helical gears in the gearbox of an automobile has been carried out. Two helical gear samples taken as representatives of the whole of six in the gearbox were denoted as samples A and B. Methods employed in the failure investigation include visual examination with the unaided eye and fractography; compositional analysis; hardness measurements and microstructural analysis. The results obtained showed that Gear sample A failed by oxidative wear essentially caused by insufficient lubrication. On the other hand, Sample B exhibited no outward sign of failure. Processes culminating in the formation of a wear particle were however noticed few micrometers below the surface of Gear Sample B. Furthermore, in the absence of sufficient lubrication, numerous carbide precipitates formed in both samples contributed to wear of the gear material. It was concluded that the premature service failures of the gears was caused by inadequate lubrication and not inadequate material selection

Changes in lipid profile of aqueous and Ethanolic extract of Blighia sapida in rats

Abstract: Aqueous and ethanolic leaf extracts of Blighia sapida was assessed for some lipid profile parameters in normal albino rats. Daily administration of the extracts (50 and 100 mg/kg body weight) for 21days showed that the extract significantly (p<0.05) reduced the levels of total cholesterol, triglycerides and LDL-cholesterol in all the treated groups when compared with the control. While significantly (p<0.05) higher value was observed for the HDL-cholesterol of all the treated groups when compared with the control, this effect was observed as dose dependent for aqueous extract. For the atherogenic indices, there was a significant (p<0.05) increase in HDL-cholesterol/Total cholesterol ratio, while LDL-cholesterol/HDL-cholesterol and log (TG/HDL-CH) ratio showed a significant (p<0.05) decrease in treated groups compared to the control group. These findings may be of clinical importance to individuals at risk of cardiovascular disease