Assessment of some mechanical properties and microstructure of particulate periwinkle shell-aluminium 6063 metal matrix composite (PPS-ALMMC) produced by two-step casting

This work investigates some mechanical properties and microstructures of PPS-AlMMC and compares the properties of the composites and those of the aluminium 6063 (AA6063) alloy. Periwinkle shells were milled to particle sizes of 75μm and 150μm and used to produce PPS-AlMMC at 1,5,10 and 15wt% filler loadings using two-step casting technique. The mechanical properties and microstructures of the composite materials were compared with those of the AA6063 alloy. It was observed that the filler distributes uniformly in the matrix due to the two-step casting technique. Improved strength, ductility, hardness and modulus were obtained when the filler was used to reinforce the alloy. However, using a filler of bigger particle size resulted to reduced tensile strength, ductility and toughness of composites.Key words: Composites, Periwinkle shell, Aluminum, Mechanical properties, Microstructur

Operability of Mobile Agent Applications in a Protected Environment

There is a shift toward increasingly heterogeneous networks in today�s communications environment. Such diversity requires that network operators have greater experience and increased training. Managing these diverse networks especially in institutions requires the collection of large quantities of data from a dependable network that must be analyzed before management of any activity can be comenced. In this research, we have identified the operability of mobile Agents in a protected network environment

Paclitaxel Succinate Analogs: Anionic Introduction as a Strategy to Impart Blood Brain Barrier Permeability

A focused library of TX-67 (C10 hemi-succinate) analogs have been prepared including regioisomeric, functional group, and one-carbon homologs. These were prepared to investigate TX-67’s lack of interaction with P-glycoprotein (Pgp). Tubulin stabilization ability, cytotoxicity, and Pgp interactions were evaluated. All carboxylic acid analogs had no apparent interactions with Pgp whereas the ester variants of the same compounds displayed characteristics of Pgp substrates. Furthermore, it is demonstrated that hydrogen-bonding properties were significant with respect to Pgp interactions. This anionic introduction strategy may allow for delivery of paclitaxel into the CNS as well as establishing a new method for delivery of other, non-CNS permeable drugs

Effects of Welding Power Input on the Microstructure and Impact Toughness of the Heat Affected Zone of 304L Austenitic Stainless Steel

The effects of welding power input on the microstructural characteristics and impact behaviour of the Heat Affected Zone (HAZ) of type 304L austenitic stainless steel were investigated. This is with a view to optimize the welding process and ensure high weldment integrity of the heat affected zone.  Chemical analysis of the as-received 304L austenitic stainless steel was determined using an Optical Emission Spectrometry AR 4 30 metal analyzer. Thereafter, 30 samples of the as-received 304L austenitic stainless steel plate with dimensions  of 70 mm length, 45 mm breadth and 8 mm thickness  were cut and labeled into A, B and C each of 10 numbers. The grouped samples were further cut into two equal halves with hacksaw and welded using Gas Metal Arc Welding (GTAW) process and 304L electrode to produce butt joint HAZ square geometry samples. The obtained HAZ and as-received samples were machined to standard charpy impact test specimens.  Also, the HAZ and as-received specimens were prepared for microscopy studies using optical microscopy. Results obtained showed that the microstructures are composed majorly of mixture of austenite and ferrite phases, also variations in volume fraction and grain size of the phases were observed under varied range of power input. In addition, chromium carbide formation and precipitation due to sensitization was seen at the grain boundaries. Optimum impact toughness (IT) of 42 J was obtained for HAZ sample at power input of 12.0 KW while the least IT of 39 J was obtained from sample welded using power input of 4.6 KW as compared with the as-received with IT of 58 J.Keywords - 304L austenitic stainless steel; gas metal arc welding; impact toughness; microstructures

Kidney function of HIV-infected children in Lagos, Nigeria: using Filler's serum cystatin C-based formula

<p>Abstract</p> <p>Background</p> <p>Limited data is available on kidney function in HIV-infected children in sub-Saharan Africa. In addition, malnutrition in these children further reduces the utility of diagnostic methods such as creatinine-based estimates of glomerular filtration rate. We determined the serum cystatin C level and estimated glomerular filtration rate of 60 antiretroviral-naïve, HIV-infected children and 60 apparently healthy age and sex matched children.</p> <p>Methods</p> <p>Serum cystatin C level was measured using enzyme-linked immunosorbent assay technique, while glomerular filtration rate was estimated using Filler's serum cystatin C formula. Student t test, Mann Whitney U test, Pearson chi square and Fisher's exact test were used, where appropriate, to test difference between groups.</p> <p>Results</p> <p>Compared to the controls, the HIV-infected group had significantly higher median (interquartile range) serum cystatin C levels {0.77 (0.29) mg/l versus 0.66 (0.20) mg/l; p = 0.025} and a higher proportion of children with serum cystatin C level >1 mg/l {10 (16.7%) versus one (1.7%); p = 0.004}. The HIV-infected children had a mean (± SD) eGFR of 96.8 (± 36.1) ml/min/1.73 m²compared with 110.5 (± 27.8) ml/min/1.73 m²in the controls (p = 0.021). After controlling for age, sex and body mass index, only the study group (HIV infected versus control) remained a significant predictor of serum cystatin C level (β = -0.216, p = 0.021). The proportion of HIV-infected children with eGFR <60 ml/min/1.73 m²was eight (13.3%) versus none (0%) in the control group (p = 0.006). However, the serum cystatin C level, eGFR and proportions of children with serum cystatin C level >1 mg/l and eGFR <60 ml/min/1.73 m²were not significantly different between the HIV-infected children with advanced disease and those with milder disease.</p> <p>Conclusions</p> <p>HIV-infected children in Nigeria have higher serum cystatin C level and lower eGFR compared to age and sex matched controls.</p

The Transfer Hydrogenation of Cinnamaldehyde Using Homogeneous Cobalt(II) and Nickel(II) (E)-1-(Pyridin-2-yl)-N-(3-(triethoxysilyl)propyl)methanimine and the Complexes Anchored on Fe3O4 Support as Pre-Catalysts: An Experimental and In Silico Approach

The imino pyridine Schiff base cobalt(II) and nickel(II) complexes (C1 and C2) and their functionalised γ-Fe3O4 counterparts (Fe3O4@C1 and Fe3O4@C2) were synthesised and characterised using IR, elemental analysis, and ESI-MS for C1 and C2, and single crystal X-ray diffraction for C1, while the functionalised materials Fe3O4@C1 and Fe3O4@C2 were characterized using IR, XRD, SEM, TEM, EDS, ICP-OES, XPS and TGA. Complexes C1, C2 and the functionalised materials Fe3O4@C1 and Fe3O4@C2 were tested as catalysts for the selective transfer hydrogenation of cinnamaldehyde and all four pre-catalysts showed excellent catalytic activity. Complexes C1 and C2 acted as homogeneous catalysts with high selectivity towards the formation of hydrocinnamaldehyde (88.7% and 92.6%, respectively) while Fe3O4@C1 and Fe3O4@C2 acted as heterogeneous catalysts with high selectivity towards cinnamyl alcohol (89.7% and 87.7%, respectively). Through in silico studies of the adsorption energies, we were able to account for the different products formed using the homogeneous and the heterogeneous catalysts which we attribute to the preferred interaction of the C=C moiety in the substrate with the Ni centre in C2 (−0.79 eV) rather than the C=O (−0.58 eV)

Fusarium and Sarocladium Species Associated with Rice Sheath Rot Disease in Sub-Saharan Africa

Sarocladium and Fusarium species are commonly identified as causal agents of rice sheath rot disease worldwide. However, limited knowledge exists about their genetic, pathogenic, and toxigenic diversity in sub-Saharan African (SSA) countries, where an increasing incidence of this disease has been observed. In this study, seventy fungal isolates were obtained from rice plants displaying disease symptoms in rice research programs and farmer fields in Mali, Nigeria, and Rwanda. Thus, an extensive comparative analysis was conducted to assess their genetic, pathogenic, and toxigenic diversity. The Fusarium spp. were characterized using the translation elongation factor (EF-1a) region, while a concatenation of Internal Transcribed Spacer (ITS) and Actin-encoding regions were used to resolve Sarocladium species. Phylogenetic analysis revealed four Fusarium species complexes. The dominant complex in Nigeria was the Fusarium incarnatum-equiseti species complex (FIESC), comprising F. hainanense, F. sulawesiense, F. pernambucatum, and F. tanahbumbuense, while F. incarnatum was found in Rwanda. The Fusarium fujikuroi species complex (FFSC) was predominant in Rwanda and Mali, with species such as F. andiyazi, F. madaense, and F. casha in Rwanda and F. annulatum and F. nygamai in Mali. F. marum was found in Nigeria. Furthermore, Fusarium oxysporum species complex (FOSC) members, F. callistephi and F. triseptatum, were found in Rwanda and Mali, respectively. Two isolates of F. acasiae-mearnsii, belonging to the Fusarium sambucinum species complex (FSAMSC), were obtained in Rwanda. Isolates of Sarocladium, which were previously classified into three phylogenetic groups, were resolved into three species, which are attenuatum, oryzae, and sparsum. S. attenuatum was dominant in Rwanda, while S. oryzae and S. sparsum were found in Nigeria. Also, the susceptibility of FARO44, a rice cultivar released by Africa Rice Centre (AfricaRice), was tested against isolates from the four Fusarium species complexes and the three Sarocladium species. All isolates evaluated could induce typical sheath rot symptoms, albeit with varying disease development levels. In addition, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine variation in the in vitro mycotoxins of the Fusarium species. Regional differences were observed in the in vitro mycotoxins profiling. Out of the forty-six isolates tested, nineteen were able to produce one to four mycotoxins. Notably, very high zearalenone (ZEN) production was specific to the two F. hainanense isolates from Ibadan, Nigeria, while Fusarium nygamai isolates from Mali produced high amounts of fumonisins. To the best of our knowledge, it seems that this study is the first to elucidate the genetic, pathogenic, and toxigenic diversity of Fusarium species associated with the rice sheath rot disease complex in selected countries in SSA

Chem4Energy: a consortium of the Royal Society Africa Capacity-Building Initiative

The Africa Capacity-Building Initiative is a Royal Society programme funded by the former UK Department for International Development to develop collaborative research between scientists in sub-Saharan Africa and the UK. Initially, four institutions were involved in the Chem4Energy consortium: Cardiff University in the UK and three African partners, the Kwame Nkrumah University of Science and Technology, Ghana, the University of Namibia and the University of Botswana, soon also including the Botswana International University of Science and Technology. The Chem4Energy research programme focused on ‘New materials for a sustainable energy future: linking computation with experiment’, aiming to deploy the synergy between state-of-the-art computational and experimental techniques to design and optimize new catalysts and semiconductor materials for renewable energy applications, based on materials that are abundant and readily available in African countries. The Chem4Energy consortium has achieved ambitious research goals, graduated seven PhD students and delivered a high-quality cross-disciplinary training programme in materials science and simulation techniques relevant to renewable energy applications. Since 2021, the extended consortium, including North-West University and the Centre for High-Performance Computing in South Africa, has remained active through an annual Chem4Energy conference series, with the sixth meeting taking place in Namibia in April 2025