7 research outputs found
Microstructural characterization and mechanical properties of carbon nanotube reinforced nickel aluminide composites
Get PDFPh.D. (Metallurgy)Abstract: Toughened nickel aluminides were successfully synthesized by incorporating multi-walled carbon nanotubes (MWCNTs) into nickel aluminide (NiAl) intermetallic matrix. The drive to retain the relative lightweight of NiAl motivated the choice of MWCNTs as the reinforcing agent in this study. Moreover, enhanced mechanical properties were anticipated in the reinforced composites owing to the exceptional properties of the MWCNTs. Elemental powders of nickel and aluminium were blended together with MWCNTs in a novel two stage ball milling for optimum dispersion and preservation of the structural integrity of the MWCNTs. The milled powders were consolidated by Spark Plasma Sintering (model HHPD- 25, FCT GmbH, Germany). The milled powders and sintered samples were characterized using Scanning Electron Microscopy, Transmission Electron Microscopy and X-Ray Diffraction. The nano-structural evolution of the MWCNTs during their dispersion via dry ball milling was further evaluated using Raman Spectroscopy. The mechanical properties and fracture behaviours of the reinforced sintered samples were critically evaluated using nanoindentation techniques. Results show that the integration of MWCNTs into the NiAl matrix led to an enhancement of the fracture toughness. An inverse relationship between the hardness and fracture toughness of the NiAl composites was established. The intergranular fracture morphology of the unreinforced NiAl transited to a dominantly dimpled fracture morphology in the NiAl-1.0 wt% CNTs composites indicating enhanced ductility and fracture toughness. The improvement of the fracture toughness of the reinforced NiAl is attributed to the uniform dispersion of theMWCNTs within the NiAl matrix, the preservation ofMWCNTs aspect ratios and the disordering of the B2 ordered NiAl intermetallic structure
LAND TENURE AND AGRICULTURAL INTENSIFICATION BY WOMEN FARMERS IN NIGERIA EFFECTS ON CROP COMMERCIALIZATION
Get PDFWomen make essential contributions to agriculture by playing a large role in food crop production. They require land as source of rural livelihood and monetary strengthening through land right security. Women’s ownership of land and property can be potentially transformative, not only as a store of value, but also as a means of acquiring other assets and engaging in a range of markets. However, women have lower access to productive resources (land and capital) compared to their male counterparts. Women are generally influenced on account of unbound land rights, particularly because of their victimization on their access to, possession and control of land. Commercialization is sometimes associated with the adoption of new technologies, which may further reduce the role of women due to poor access to land. This paper broadly examines land tenure and agricultural intensification by women farmers in Nigeria, and their effects on crop commercialization. Specifically, this paper examines land tenure systems, analyzed agricultural intensification and evaluated crop commercialization among women farmers in Nigeria. The Nigeria General Household Survey (GHS) 2018 were used. Data for 1,962 women farmers were extracted from the dataset. These include socioeconomic characteristics of women farmers as well as information on land tenure systems, agricultural intensification and crop commercialization. Data were analysed using descriptive statistics to examine land tenure systems, Ruthenberg Index, Labour Use Intensity, and Fertilizer Use Intensity to analyze agricultural intensification, Crop Commercialization Index (CCI) to evaluate crop commercialization and Tobit Regression Model to measure the effects of land tenure systems and agricultural intensification on crop commercialization among women farmers in Nigeria. Results show that the total number of plots held by women was 2,378 and the average farm size cultivated was 0.43hectare. Women gained access to land mainly by inheritance (42.9% of the plots). Though there are restrictions on land inheritance by women in some cultures, they have been able to have access to farm plots by land market; through outright purchase (39.9%) and rent (8.4%). Results on agricultural intensification show that the mean land use intensity was 0.26(±0.26). Also, on the average, labour use was approximately 55mandays/hectare and fertilizer use was 728kg/hectare. Crop commercialization results show that almost three-quarters (71.10%) of the women farmers were market oriented at different levels (0%<CCI<100%), 28.9% were fully subsistent (CCI=0%) and 2.30% fully commercialized their farm produce (CCI=100%). The mean CCI was 29.5(±31.3), meaning that only 29.5% of the quantity of the crops produced was commercialized. Tobit regression results show that land tenure systems and agricultural intensification have positive significant effects on crop commercialization among women farmers in Nigeria. Crop commercialization is low among women farmers. Land access and intensification improve crop commercialization by women farmers in Nigeria. There should be upgrading of informal land rights to legally enforceable rights for women farmers to provide greater protection (tenure security) for the women
Influence of sintering methods on the mechanical properties of aluminium nanocomposites reinforced with carbonaceous compounds: A review.
No full textThis paper succinctly reviews from the corpus of literature the reinforcement of aluminium with carbonaceous nanocompounds (CNTs, GNPs, graphenes etc.), with particular emphasis on the strength and ductility of the resulting composites based on the utilized fabrication routes. Owing to the unique intrinsic properties of these carbonaceous nanocompounds, they have been widely reported as ideal reinforcement materials for aluminium and its compounds. Significant amount of work has been published on the use of solid-state sintering as a novel route for the incorporation of these nanocompounds in aluminium matrices. This paper therefore aims to review some relevant aspects of the fabrication processes of
these aluminium based composites such as (i) effects of the sintering routes and parameters on the resulting properties of the composites; (ii) the effect of dispersion techniques on the resulting properties of the composites; (iii) the strength-ductility trade-off in the reinforced composites; and (iv) the intermetallics formed between the carbonaceous nanocompounds and aluminium
The effect of alloying additions on the mechanical properties of nickel aluminide NiAl — A review
No full textInfluence of sintering methods on the mechanical properties of aluminium nanocomposites reinforced with carbonaceous compounds: A review
No full textNurses’ knowledge and willingness to recommend malaria vaccination to caregivers of under-5 in Nigeria: a nationwide survey
No full textAbstract Background Malaria is a major public health problem in Nigeria. This study set out to ascertain Nigerian nurses' knowledge and willingness to recommend malaria vaccination to caregivers of under-5 children. Methods This was a cross-sectional study carried out among nurses from all six geopolitical zones of Nigeria. A pretested semi-structured questionnaire was used to collect data on participants' demographics, their knowledge of the RTS S/AS01 and R21 Matrix M malaria vaccines, how they obtain malaria vaccine-related information, and the factors that the nurses consider when recommending any malaria vaccine. Univariate association between each of the demographics characteristics and the key research variables: knowledge of the vaccine and willingness to recommend was used. This was examined using the Chi-Square test and multiple logistic regression. Results The study found that nearly two out of every three nurses had poor knowledge and perception of the vaccines (p < 0.05). Awareness of the malaria vaccine was the only factor that was found to be associated with their knowledge (p <0.05). The odds of willingness to promote the vaccine were about 21 times higher among nurses with high perceptions of efficacy than their counterparts who have low perceptions. Conclusions The findings highlight major gaps in Nigerian nursing's knowledge and awareness of malaria vaccinations, as well as their willingness to recommend the vaccine to parents. Addressing these gaps will enable nurses to play a critical role in the successful implementation of malaria immunization campaigns, lowering the illness burden among vulnerable populations
Proceedings of the International Workshop on Social Impact of AI for Africa 2022
Get PDFThis workshop proceedings contain articles on the various research ideas of the International Workshop on Social Impact of AI for Africa 2022 (SIAIA-22). This Workshop served as a critical juncture in the academic exploration of Artificial Intelligence (AI) within the African context. As an auxiliary event of the thirty-sixth AAAI Conference on Artificial Intelligence (AAAI-22), the workshop was positioned at the forefront of ongoing international scholarly discourse on the social implications and equitable deployment of AI technologies in Africa. SIAIA-22 was Organized by the AAAI Diversity and Inclusion Program, United States on 26 February 2022.
Workshop Title: International Workshop on Social Impact of AI for Africa 2022Workshop Acronym: SIAIA-22Workshop Date: 16 February 2022Workshop Location: OnlineWorkshop Organizers: AAAI Diversity and Inclusion Program, United State
