Numerical Modeling of Fluid Flow and Thermal Transport in Gravity - Dominated 3D Microchannels

The success recorded by the usage of microchannel in high flux cooling application, has led to several studies aimed at advancement in microchannel fluid flow and heat transfer technology. A recent study area with promising breakthrough is the effects of g ravity on microscale flow. Numerical simulations were conducted to study single phase flow and heat transfer in 3D microchannels. A priori, the 3D models were validated with experimental results and showed agreement. Two different aspects were simulated: f irstly a microchannel with hydraulic diameter of Dh =199 휇푚 for gravity effects on heat transfer. Secondly, gravity effects on friction factor with hydraulic diameter Dh = 1587 휇푚 . The 3D model confirmed the existence of gravity effects and scaled with significant factors previous 2D model predictions. This result realistically presents the potential of microchannel angular orientation as a passive tool for flow optimization and heat enhancement in portable electronics devices and compact - sized biomedic al devices

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

Development of an Efficient Chamber for Green-Drying Moringa Oleifera Leaves

The Moringa oleifera (M. oleifera) leaves are very nutritious leaves, rich in protein, vitamins and minerals. The leaves are also used for varied applications such as nutritional and medicinal purposes. This potential presents M. oleifera as a leaf with economic cum health prospects especially to agrarian communities. To sustain these potential benefits of M. oleifera, a means of processing them has to be developed and this process must not in any way reduce the nutritional value of the leaves. Drying under room condition is a usual process practice for M. oleifera, this is quite remote and would not encourage large scale production which could determine the economic feasibility. However, several efforts have been reported for processing M. oleifera, yet the balance between drying and retention of nutritional content is yet to be established for mechanized drying process. Therefore, there is the need to develop a mechanized chamber for green-drying M. oleifera. In this work, development of an efficient drying chamber was addressed using indigenous materials. The machine was designed, constructed and tested using fresh M. oleifera leaves. The machine is electrically-controlled via a switch and a thermocouple that will cut off the heater chamber when the required temperature is reached. To test the effectiveness of the dryer, M. oleifera leaves were dried using the designed dryer and the same quality dried using the room method. The method was able to dry M. oleifera leaves about three (3) hours compared to four (4) to seven (7) hours using the room method. The two samples were then sent to a laboratory for analysis. For nutrients like crude fibre of the sample dried using the new design yielded 7.4% crude fibre which is very close to 7.5% nutritional crude fibre content with room drying method. The drying chamber presented in this study showed efficient greendrying performance of M. oleifera with high nutritional content retention. The drying chamber presented in this work has the potential to benefit medium-scale production of M. oleiferawith nutritional components.Keywords: Nutritional leaves, drying, processing, chamber, minerals, medium-scale productio

The effects of solvent extracts of Citrulluslanatus seeds and Chrysophyllum albidum cotyledons on rat hepatocyte regeneration, cytochrome c oxidase activities and bacteriocin- producing gram-negative bacteria

Medicinal plants have been shown to exert a plethora of biological and pharmacological which has been associated with the presence of several bioactive components. In this study, the effects of crude extracts of Citrullus lanatus seeds (CACL) and Chrysophyllum albidum cotyledons (CACA) on rat hepatocyte regeneration, liver cytochrome c oxidase activities, and their antimicrobial properties on a few bacteriocin-producing Gram-negative bacteria were determined. CACL and CACA were screened for the presence of amino acids using TLC sprayed with ninhydrin, pyridine and modified Commassie brilliant blue (G250). The amino acids were elucidated by Gas Chromatography-Mass Spectrometry (GC/MS) and Fourier-transform infrared spectroscopy (FTIR). CACA enhanced tissue regeneration in rat hepatocytes, in situ and increased the collagen content. CACA also enhanced the activity cytochrome c oxidase in the liver mitochondrial portion, but inhibited same in the homogenate. CACA and CACL did not inhibit the bacteriocin-producing bacteria at the different concentrations tested. It is evident that CACA and CACL contain amino acids that can improve liver antioxidant functions and its mitochondrial electron transport. Both amino acid-rich fractions, combined with bacteriocin may accelerate aseptic wound healing.Fil: Molehin, O. R.. Ekiti State University; NigeriaFil: Ajayi, Ebenezer Idowu O. Department Of Biochemistry, Osun State University; Nigeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Attah, A. F.. University of Ibadan; NigeriaFil: Awope, O. R.. Osun State University; NigeriaFil: Ige, E. T.. Ekiti State University; NigeriaFil: Omotoyinbo, O. E.. Ekiti State University; NigeriaFil: Aladetuyi, B. J.. Ekiti State University; Nigeri

Thermo-economic comparative analysis of a simple and cascaded organic Rankine power plants fired by rice husks

The application of organic working fluids in the Organic Rankine Cycle (ORC) has been demonstrated to be an attractive option for shifted integrated power and heat production. The procedure allows for the implementation of low-temperature heat sources, which provides advantages in small-scale uses. This study models the organic Rankine cycle for use with rice husk waste from a typical agricultural farm. The comparative analysis of agro-fired simple and cascaded organic Rankine power plants. Toluene and R245fa were considered as the working fluids for both simple and cascaded ORCs. Basic thermodynamic and economic governing equations were utilized in the analyses and embedded in the Engineering Equation Solver. The net powers, energy, exergy, and economic analyses of the two ORCs form the basis for comparison. Afterward, sensitivity analysis was carried out to ascertain the effects of variability of pertinent parameters on the plants. Results revealed that the net power output, thermal and exergy efficiencies of the simple and cascade ORC plants were 1.154 MW, 15.53% and 20.38%, and 1.599 MW, 21.51%, and 28.23%, respectively. The largest exergy destruction rate was obtained in the combustion chamber (1531 kW), and the least exergy destruction was recorded in the recirculation working fluid pump (1.073 kW). The simple ORC showed better economic performance as reflected in the unit cost of energy of 35.11 N/kWh as against 37.68 N/kWh of the cascaded ORC. The proposed energy system has the potential for a viable business enterprise based on the favorable Federal Government of Nigeria's fiscal and energy policies

Experience of quality management system in a clinical laboratory in Nigeria

Issues: Quality-management systems (QMS) are uncommon in clinical laboratories in Nigeria, and until recently, none of the nation’s 5 349 clinical laboratories have been able to attain the certifications necessary to begin the process of attaining international accreditation. Nigeria’s Human Virology Laboratory (HVL), however, began implementation of a QMS in 2006, and in 2008 it was determined that the laboratory conformed to the requirements of ISO 9001:2000 (now 2008), making it the first diagnostic laboratory to be certified in Nigeria. The HVL has now applied for the World Health Organization (WHO) accreditation preparedness scheme. The experience of the QMS implementation process and the lessons learned therein are shared here. Description: In 2005, two personnel from the HVL spent time studying quality systems in a certified clinical laboratory in Dakar, Senegal. Following this peer-to-peer technical assistance, several training sessions were undertaken by HVL staff, a baseline assessment was conducted, and processes were established. The HVL has monitored its quality indicators and conducted internal and external audits; these analyses (from 2007 to 2009) are presented herein. Lessons learned: Although there was improvement in the pre-analytical and analytical indicators analysed and although data-entry errors decreased in the post-analytical process, the delay in returning laboratory test results increased significantly. There were several factors identified as causes for this delay and all of these have now been addressed except for an identified need for automation of some high-volume assays (currently being negotiated). Internal and external audits showed a trend of increasing non-conformities which could be the result of personnel simply becoming lax over time. Application for laboratory accreditation, however, could provide the renewed vigour needed to correct these non-conformities. Recommendation: This experience shows that sustainability of the QMS at present is a cause for concern. However, the tiered system of accreditation being developed by WHO–Afro may act as a driving force to preserve the spirit of continual improvement

Full length genomic sanger sequencing and phylogenetic analysis of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Nigeria.

In an outbreak, effective detection of the aetiological agent(s) involved using molecular techniques is key to efficient diagnosis, early prevention and management of the spread. However, sequencing is necessary for mutation monitoring and tracking of clusters of transmission, development of diagnostics and for vaccines and drug development. Many sequencing methods are fast evolving to reduce test turn-around-time and to increase through-put compared to Sanger sequencing method; however, Sanger sequencing remains the gold standard for clinical research sequencing with its 99.99% accuracy This study sought to generate sequence data of SARS-CoV-2 using Sanger sequencing method and to characterize them for possible site(s) of mutations. About 30 pairs of primers were designed, synthesized, and optimized using endpoint PCR to generate amplicons for the full length of the virus. Cycle sequencing using BigDye Terminator v.3.1 and capillary gel electrophoresis on ABI 3130xl genetic analyser were performed according to the manufacturers' instructions. The sequence data generated were assembled and analysed for variations using DNASTAR Lasergene 17 SeqMan Ultra. Total length of 29,760bp of SARS-CoV-2 was assembled from the sample analysed and deposited in GenBank with accession number: MT576584. Blast result of the sequence assembly shows a 99.97% identity with the reference sequence. Variations were noticed at positions: nt201, nt2997, nt14368, nt16535, nt20334, and nt28841-28843, which caused amino acid alterations at the S (aa614) and N (aa203-204) regions. The mutations observed at S and N-gene in this study may be indicative of a gradual changes in the genetic coding of the virus hence, the need for active surveillance of the viral genome