Mechanical and Morphological Properties of Bio-Phenolic/Epoxy Polymer Blends.

Polymer blends is a well-established and suitable method to produced new polymeric materials as compared to synthesis of a new polymer. The combination of two different types of polymers will produce a new and unique material, which has the attribute of both polymers. The aim of this work is to analyze mechanical and morphological properties of bio-phenolic/epoxy polymer blends to find the best formulation for future study. Bio-phenolic/epoxy polymer blends were fabricated using the hand lay-up method at different loading of bio-phenolic (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) in the epoxy matrix whereas neat bio-phenolic and epoxy samples were also fabricated for comparison. Results indicated that mechanical properties were improved for bio-phenolic/epoxy polymer blends compared to neat epoxy and phenolic. In addition, there is no sign of phase separation in polymer blends. The highest tensile, flexural, and impact strength was shown by P-20(biophenolic-20 wt% and Epoxy-80 wt%) whereas P-25 (biophenolic-25 wt% and Epoxy-75 wt%) has the highest tensile and flexural modulus. Based on the finding, it is concluded that P-20 shows better overall mechanical properties among the polymer blends. Based on this finding, the bio-phenolic/epoxy blend with 20 wt% will be used for further study on flax-reinforced bio-phenolic/epoxy polymer blends.

Tetanus and Diphtheria Seroprotection among Children Younger Than 15 Years in Nigeria, 2018: Who Are the Unprotected Children?

Serological surveys provide an objective biological measure of population immunity, and tetanus serological surveys can also assess vaccination coverage. We undertook a national assessment of immunity to tetanus and diphtheria among Nigerian children aged <15 years using stored specimens collected during the 2018 Nigeria HIV/AIDS Indicator and Impact Survey, a national cross-sectional household-based survey. We used a validated multiplex bead assay to test for tetanus and diphtheria toxoid-antibodies. In total, 31,456 specimens were tested. Overall, 70.9% and 84.3% of children aged <15 years had at least minimal seroprotection (≥0.01 IU/mL) against tetanus and diphtheria, respectively. Seroprotection was lowest in the north west and north east zones. Factors associated with increased tetanus seroprotection included living in the southern geopolitical zones, urban residence, and higher wealth quintiles (p < 0.001). Full seroprotection (≥0.1 IU/mL) was the same for tetanus (42.2%) and diphtheria (41.7%), while long-term seroprotection (≥1 IU/mL) was 15.1% for tetanus and 6.0% for diphtheria. Full- and long-term seroprotection were higher in boys compared to girls (p < 0.001). Achieving high infant vaccination coverage by targeting specific geographic areas and socio-economic groups and introducing tetanus and diphtheria booster doses in childhood and adolescence are needed to achieve lifelong protection against tetanus and diphtheria and prevent maternal and neonatal tetanus.

Baseline study for improving diagnostic stewardship at secondary health care facilities in Nigeria.

BACKGROUND: Blood culture diagnostics are critical tools for sepsis management and antimicrobial resistance (AMR) surveillance. A baseline study was conducted to assess reported sepsis case finding, blood culture diagnostics, antimicrobial susceptibility testing (AST) and antimicrobial use at secondary health care facilities to inform the development of diagnostic stewardship improvement strategies in Nigeria. METHODS: A cross-sectional online survey was conducted among 25 public secondary health care facilities in Abuja, Federal Capital Territory (FCT) and Lagos State in Nigeria to evaluate the capacity for pathogen identification and AST. Data were then prospectively extracted on all patients with reported suspected sepsis from electronic medical records from selected departments at two facilities in the Federal Capital Territory from October 2020 to May 2021 to further assess practices concerning sepsis case-finding, clinical examination findings, samples requested, and laboratory test results. Data were descriptively analysed, and a multivariate logistic regression analysis was conducted to determine factors associated with blood culture requests. RESULTS: In the online survey, 32% (8/25) of facilities reported performing blood cultures. Only one had access to a clinical microbiologist, and 28% (7/25) and 4% (1/25) used standard bacterial organisms for quality control of media and quality control strains for AST, respectively. At the two facilities where data abstraction was performed, the incidence of suspected sepsis cases reported was 7.1% (2924/41066). A majority of these patients came from the paediatrics department and were outpatients, and the median age was two years. Most did not have vital signs and major foci of infection documented. Blood cultures were only requested for 2.7% (80/2924) of patients, of which twelve were positive for bacteria, mainly Staphylococcus aureus. No clinical breakpoints were used for AST. Inpatients (adjusted odds ratio [aOR]: 7.5, 95% CI: 4.6-12.3) and patients from the urban health care facility (aOR:16.9, 95% CI: 8.1-41.4) were significantly more likely to have a blood culture requested. CONCLUSION: Low blood culture utilisation remains a key challenge in Nigeria. This has implications for patient care, AMR surveillance and antibiotic use. Diagnostic stewardship strategies should focus on improving access to clinical microbiology expertise, practical guidance on sepsis case finding and improving blood culture utilisation and diagnostics.

Thermo-oxidative stability and flammability properties of bamboo/kenaf/nanoclay/epoxy hybrid nanocomposites.

In this study, three types of nanoclay [halloysite nanotube (HNT), montmorillonite (MMT) and organically modified MMT (OMMT)] were incorporated into bamboo/kenaf (B/K) reinforced epoxy hybrid composites to compare their thermo-oxidative (TOD) stability and flammability properties. B/K (50 : 50) hybrid nanocomposites were fabricated by adding 1% loading (by weight) nanoclay through a hand lay-up technique. Wide angle X-ray scattering (WAXS) and field emission scanning electron microscopy (FESEM) were used to study the morphology of the nanoclay-epoxy mixture. The TOD stability of the hybrid nanocomposites was studied with a thermogravimetry analyzer (TGA) under oxygen atmosphere. The flammability properties were evaluated using the Underwriters Laboratories 94 horizontal burning test (UL-94HB), limiting oxygen index (LOI), cone calorimetry and smoke density test. The morphological study reveals that MMT/epoxy and HNT/epoxy are highly agglomerated while OMMT/epoxy reveals a more uniform distribution morphology. The obtained results reveal that B/K/HNT shows better TOD stability below 300 °C, but B/K/MMT and B/K/OMMT show high residue content and decomposition temperatures above 300 °C. The flame retardancy of the hybrid nanocomposites improved with the loading of all types of nanoclay, but B/K/OMMT shows higher flame retardancy than B/K/MMT and B/K/HNT hybrid nanocomposites. Hybrid nanocomposites show improvement in flame properties in terms of peak heat release rate (pHRR), total heat release, fire growth rate index (FIGRA) and maximum average rate of heat emission (MARHE) and smoke growth rate index (SMOGRA) indicators. The findings from this work can be utilized to prepare high-performance fire retardant natural fiber reinforced epoxy hybrid composites for automotive and construction applications to save human lives.

Improved Mechanical and Moisture-Resistant Properties of Woven Hybrid Epoxy Composites by Graphene Nanoplatelets (GNP).

This research investigated the effect of adding different wt.% (0, 0.25, 0.50, and 0.75) of GNP (graphene nanoplatelets) to improve the mechanical and moisture resistant properties of Kevlar (K)/cocos nucifera sheath (CS)/epoxy hybrid composites. The laminates were fabricated with different K/CS weight ratios such as 100/0 (S1), 75/25 (S2), 50/50 (S3), 25/75 (S4), and 0/100 (S5). The results revealed that the addition of GNP improved the tensile, flexural, and impact properties of laminated composites. However, the optimal wt.% of GNP varies with different laminates. A moisture diffusion analysis showed that the laminates with a 0.25 wt.% of GNP content efficiently hindered water uptake by closing all the unoccupied pores inside the laminate. Morphological investigations (SEM and FE-SEM (Field Emission Scanning Electron Microscope)) proved that the addition of GNP improved the interfacial adhesion and dispersion. Structural (XRD and FTIR) analyses reveals that at 0.25 wt.% of GNP, all the hybrid composites showed a better crystallinity index and the functional groups presents in the GNP can form strong interactions with the fibers and matrix. A statistical analysis was performed using One-way ANOVA, and it corroborates that the mechanical properties of different laminates showed a statistically significant difference. Hence, these GNP-modified epoxy hybrid composites can be efficiently utilized in load-bearing structures.

Enhanced Thermal and Dynamic Mechanical Properties of Synthetic/Natural Hybrid Composites with Graphene Nanoplateletes.

The aim of the present research work is to enhance the thermal and dynamic mechanical properties of Kevlar/Cocos nucifera sheath (CS)/epoxy composites with graphene nano platelets (GNP). Laminates were fabricated through the hand lay-up method followed by hot pressing. GNP at different wt.% (0.25, 0.5, and 0.75) were incorporated with epoxy resin through ultra-sonication. Kevlar/CS composites with different weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) were fabricated while maintaining a fiber/matrix weight ratio at 45/55. Thermal degradation and viscoelastic properties were evaluated using thermogravimetric analysys (TGA), differential scanning calorimetric (DSC) analysis, and a dynamic mechanical analyser (DMA). The obtained results revealed that Kevlar/CS (25/75) hybrid composites at 0.75 wt.% of GNP exhibited similar thermal stability compared to Kevlar/epoxy (100/0) composites at 0 wt.% of GNP. It has been corroborated with DSC observation that GNP act as a thermal barrier. However, DMA results showed that the Kevlar/CS (50/50) hybrid composites at 0.75 wt.% of GNP exhibited almost equal viscoelastic properties compared to Kevlar/epoxy (100/0) composites at 0 wt.% GNP due to effective crosslinking, which improves the stress transfer rate. Hence, this research proved that Kevlar can be efficiently (50%) replaced with CS at an optimal GNP loading for structural applications.