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Optimal Mixture of Materials and Condition in Producing Flat Glasses for Automobile Windscreens in Nigeria
No full textThe selection of materials is an essential element for engineering designers. This study investigated the optimal mixture of materials and condition in producing flat glasses for automobile windscreens in Nigeria. To achieve this, 10 pairs of compositions of material mixtures and cullet (broken glasses) were used. The standard material mixture (80/20 wt. % of material mix/cullet) from the local industry was modified to have batches of up to 60/40 wt. % material mix/cullet. These material mixtures were used to produce flat glasses by adopting procedures of industrial float glass process of Pilkington Brothers in variable conditions of annealing temperature and time. The average density of each pair of flat glass was measured using water displacement method, and each pair was later laminated to produce a total of 10 automobile windscreens. The windscreens were subjected to 2.25kg drop ball impact test from a height of 4m at 900. The study revealed that the density of the flat glass produced was significantly (p< 0.01) related to squared composition (wt. %) of cullet (R2=97.65%). The highest and lowest densities of 2.23g/cm3 and 1.95g/cm3 were obtained at cullet inclusions of 40 wt. % and 20 wt. % respectively at constant annealing temperature (5500C) and time (60 min). The optimal batch obtained composed of 40 wt. % cullet inclusion, annealed at 5000C for 50 minutes. Increased cullet composition was found to reduce the melting temperature of the batch mixture and fractured characteristics of the windscreens produced. Employing this design in the windscreens manufacturing industry saves production cost, facilitates a competitive market, enhance the quality of windscreens, reduce emissions and curb environmental degradation
Determination of performance and associated economic costs of indirect air-cooling combined with evaporative cooling for storage of tomatoes in South Africa
No full textKnowledge of the cost of a storage structure for fruits and vegetables is paramount as a decision tool when farmers consider the return on investment. The performance and economic analysis associated with using a solar-powered indirect air-cooling (IAC) combined with evaporative cooling (EC) storage structure for storage of green harvested tomatoes was investigated. This study investigated the effect of IAC+EC system and period of storage on the quality of tomatoes over a 28 day storage period. The construction, maintenance and operation costs of an IAC+EC system were also studied. Various quality attributes of tomatoes were investigated by monitoring the storage of green harvested tomato fruit over 28 days under both IAC+EC system and ambient conditions with data collated every seven days. Tomatoes stored under IAC+EC conditions had significantly (P<0.01) higher firmness, lower total soluble solids content, lower physiological weight loss and higher average percentage marketability than those under ambient conditions over the storage period. The tomatoes stored in the cold storage conditions were 28.1% more resistant to puncture; had 7,3% less total soluble solids content, had three times less physiological weight loss, than those stored under ambient conditions over the same period. The h° and L* values decreased progressively over the period of storage from 84% at day 0 to 48.31% and 50.43% at day28 under ambient and IAC+EC conditions, respectively. Tomatoes stored under IAC+EC conditions had a higher average percentage marketability (72.4%) than those under ambient conditions (40.9%) over the storage period. The cost of constructing a 53-m3 IAC+EC system integrated with a solar photovoltaic system was US$8,680. The economic analysis that the payback period of the cooling system was less than two years. The results demonstrate that the IAC+EC system could be recommended for small-scale farmers in sub-Saharan Africa to maintain a better quality of produce if government and other funding agencies come on board. 
Effect of varied calcium formulations and time of application on postharvest quality and organoleptic acceptability of mango fruits
No full textMango (Mangifera indica L.) is a highly perishable fruit with a short shelf life at ambient conditions, which may lead to post-harvest losses approximated to be 40-45%. This reduces returns to farmers significantly. The problem is compounded by the fact that most farmers do not have access to cold storage facilities. Nutrient management has been shown to affect postharvest characteristics of fruits. Calcium particularly plays a critical role in cell membrane integrity, tissue firmness and delays lipid catabolism. Previous studies have indicated a deficiency of calcium in some mango growing regions in Kenya. A field study was carried out to determine the effect of varied calcium formulations applied at various stages of growth on mango fruits post-harvest quality and organoleptic acceptability. The study was carried out in Embu County Eastern Kenya during seasons 2017/2018 and 2018 /2019 using “Van Dyke” cultivar, aged approximately 10 years. The experiment was set up in a randomized complete block design with a split-split plot arrangement, three trees per replication, replicated thrice. Three calcium formulations: calcium chloride, calcium nitrate and Easygro™ were applied at rates of 0%,1.0%, 1.5% and 2.0% at fruit set, 30 days after fruit set and 30 days to physiological maturity. The calcium sources formed the main plots, the timing of application formed the subplots while the rates of application formed the sub-sub plots. Total soluble solids (TSS) and percentage titratable acidity (TA) were assessed at harvest and after 12 days of storage under ambient conditions (25±2ºC, 70±5% relative humidity) using standard procedures. Selected fruits’ sensory attributes were also evaluated after storage using a hedonic scale. Analysis of data was done using the 14th Edition of the Genstat software. The differences among the means of the treatments were compared using Fisher’s Protected LSD test at 5% probability level. Fruits sprayed with calcium chloride, 2.0% at fruit set had higher TSS (6.8 º brix and 6.3º brix) (10.47 º brix and 9.10 º brix), TA (1.29% and 1.27%), (0.77% and 0.675%) than other treatments at maturity and after storage in both seasons, respectively. Calcium chloride at 2.0% level of application led to a superior peel color appearance contrary to calcium nitrate and Easygro™ also applied at 2.0%, which led to an inferior peel color appearance and an inferior taste of fruits. Therefore, calcium nitrate and easy gro should be sprayed at concentration of 1.5% for good taste and peel colour appearance. 
Quality compliance of fruits and vegetables sold at Street Vending Sites of Tshwane, South Africa
Get PDFThe selling of fruits and vegetables in the street is a common phenomenon in developing countries due to high levels of unemployment. In South Africa, street vending of fruits and vegetables brings valuable income to many impoverished households, thereby improving the livelihoods of people who are not formally employed. The Agricultural Product Standards Act No. 119 of 1990 of South Africa provides for the standardisation of quality norms for agricultural produce. Enforcing the Agricultural Product Standards Act is essential to ensure that agricultural produce sold in the streets is regulated and controlled so it is safe throughout the supply chain from the farm to the vending site. The purpose of this research was to investigate quality compliance of fresh fruits and vegetables sold by street vendors in the Tshwane metropolis, South Africa. A cross-sectional study survey was conducted in which stratified random sampling was used to sample 200 fresh fruit and vegetable vendors. Their knowledge of the requirements of the Agricultural Product Standards Act of South Africa was analysed. The compliance of their produce with quality regulations and the level of monitoring by authorities were also evaluated. Most respondents (89%) did not know about the Act. Only a small majority of fruit (51.5%) and vegetable (56%) retailers indicated that their agricultural products had been monitored. A large majority of fruits (86% to 99.8%) and vegetables (85.4% to 97.5%) met all the quality requirements in the Act. In general, a fair proportion of fruits (58%) and vegetables (65%) complied with the requirements of the Act. There was a significant positive correlation (p≤0.05) between monitoring by officials and the level of compliance. Only a small percentage of fresh fruits and vegetables vending sites are monitored by authorities. This paper is of interest to stakeholders in street vending of agricultural food produce because it raises awareness of areas of non-compliance and a need for effective compliance. Awareness and adequate enforcement can translate into selling and consuming agricultural high quality and safe food produce on the streets of Tshwane metropolis. 
Synthesis, characterization and DFT studies of Schiff bases of p-methoxysalicylaldehyde
Get PDFABSTRACT. Five new Schiff bases synthesized by the reaction between 2-(methylthio)aniline derivatives and p-methoxysalicylaldehyde are presented as MtH-1 (R = H), MtH-2 (R = CH3), MtH-3 (R = OCH3), MtH-4 (R = Cl) and MtH-5 (R = Br). They were characterized by CHNS analyses, NMR (1H, 13C, DEPT135, COSY and HSQC), FTIR and UV-Vis spectroscopic techniques. FT-IR, elemental analyses and NMR data supported the formation of the Schiff bases, with the chemical shifts of azomethine and phenol protons showing sensitivity to ring substitution. The crystal structure of MtH-1 featured the alignment of the phenyl rings to each other and to the C=N group with dihedral angles >170o. The DFT calculations corroborated the bond lengths and angles of MtH-1. The HOMO-LUMO energies, dipole moments and other reactivity parameters were calculated. The methyl-substituted MtH-2 was the least polar of the compounds. With calculated energy band gaps of almost 4 eV, the compounds may have applications in the semiconductors field.
Bull. Chem. Soc. Ethiop. 2023, 37(3), 675-688.
DOI: https://dx.doi.org/10.4314/bcse.v37i3.11
KEY WORDS: Schiff bases, p-methoxysalicylaldehyde, Crystal structure, Spectroscopic properties, DFT calculation
Net convergence structures with applications to vector lattices
No full textConvergence is a fundamental topic in analysis that is most commonly modeled using topology. However, there are many natural convergences that are not given by any topology; e.g., convergence almost everywhere of a sequence of measurable functions and order convergence of nets in vector lattices. The theory of convergence structures provides a framework for studying more general modes of convergence. It also has one particularly striking feature: it is formalized using the language of filters. This paper develops a general theory of convergence in terms of nets. We show that it is equivalent to the filter-based theory and present some translations between the two areas. In particular, we provide a characterization of pretopological convergence structures in terms of nets. We also use our results to unify certain topics in vector lattices with general convergence theory
New approach to property (ω) for functions of operators
No full textLet H be an infinite dimensional complex Hilbert space and B(H) be the algebra of all bounded linear operators on H. For T ∈ B(H), we say T satisfies property (ω) if σa(T) \ σea(T) = π00(T), where π00(T) = {λ ∈ isoσ(T) : 0 < n(T − λI) < ∞}. In this paper, we research on the property (ω) for functions of operators by using the new spectrum σvea(T) which is a variant of the Weyl essential approximate point spectrum. At the same time, the stability of SVEP as well as the relationships between the two parts is also given
Survey of plant parasitic nematodes and disease severity of common bean lines evaluated for reaction to root knot nematodes infestation
Get PDFPlant parasitic nematodes are important pests in crop production in sub-Saharan Africa. The objective of this study was to identify the occurrence of nematodes associated with common bean (Phaseolus vulgaris L.) and evaluate breeding lines for their reaction to Meloidogyne spp. in Ghana. Common bean rhizosphere soil was sampled and processed using Modified Baermann Tray method. Five nematode genera, namely Meloidogyne, Pratylenchus, Rotylenchulus, Helicotylenchus and Trichodorus were extracted. The first four genera listed above were prevalent across locations, with Trichodorus present in 30% of the fields sampled. The highest nematode population density of 319 juveniles per 200 cubic centimeter of soil was recorded for Meloidogyne spp. compared to 45 juveniles per 200 cubic centimeter, for Trichodorus. Twelve breeding lines were evaluated by inoculating roots of two-weeks-old plants with 2000 infective-stage juveniles of Meloidogyne sp. Reactions of test lines to Meloidogyne sp. infection were assessed by determining the number of egg masses and galling index (GI) on roots. Reproduction index (RI) was used to classify test lines as resistant or susceptible. Significant differences (P < 0.05) were observed in the number of eggs, GI and RI among lines tested. No resistant line was identified; however, lines SEF 47, BFS 35 and BFS 60 were moderately resistant, with RI of 13.1, 17.4 and 23.7%, respectively. Line SEF 60, although classified as slightly resistant, recorded a 100 seed weight of 26.0 g, which was 60% higher than line SEF 53 with seed weight of 16.2 g. Moderately resistant common bean lines identified could be used in common bean improvement programmes to develop elite cultivars tolerant to root knot nematodes. 
Seasonal evaluation of yield and yield component traits of thirteen okra genotypes in a derived savannah
No full textTen improved okra genotypes obtained from National Institute for Horticultural Research and Training, Okigwe, Nigeria and three local cultivars were evaluated under early and late planting seasons of 2014 and 2015. The aim of this study is to estimate the relationship and magnitude of direct effects among the traits as well as determine the degree of heritability and variability among the genotypes. Genotypic stability analysis was also performed on the yield and the two traits most related to yield. ‘Ele Uhie’ genotype had the highest values for most of the parameters measured for both early and late planting seasons. Among the improved genotypes, ‘TAE 38’ had relatively appreciable yield. In both seasons, all the traits studied showed positive and significant (p < 0.01) correlation with total fruit yield, although number of fruits/plant and plant height at maturity had the strongest relationship. The yield stability estimates showed that the genotypes independently expressed their traits in the four different stability groups. Path coefficient analysis revealed that number of fruits/plant and plant height at maturity had higher positive and higher magnitude of direct effect than the direct effects of the associated parameters studied for both planting seasons. Thus, selecting ‘Ele Uhie’, ‘Ele Ogwu’, ‘Ele Ndu’ and ‘TAE 38’ genotypes with relatively stable and high number of fruits/plant and plant height at maturity would have greater impact in sustaining high yields in okra
Environmental factors affecting pre-weaning mortality of Turkish Saanen kids
No full textOne of the most important problems encountered in breeding Turkish Saanen goats, the dominant dairy goat in Turkey, is the death of kids. Deaths cause serious economic losses and jeopardize the need for qualified breeders. This study aimed to determine the factors that affected the survival of kids in the period between birth and weaning, when most deaths are observed. A total of 3343 records of Turkish Saanen kids were collected in 2019. The importance and order of the effects of environmental factors, such as gender, birth type, sex, birth weight, farm, season of birth, weight at death, and maternal age at the kid’s mortality were determined by using the decision tree statistical method. As a result of this study, the farm effect was the first effective factor in the survivability of kids, and death was less common in small farms (F3), with a rate of 7.8%. The death times of kids were divided into four groups: birth–first 24 hours (M1), 1–7 days (M2), 7–30 days (M3), and 30 days–weaning (90 days) (M4). Deaths were highest in M2 with 40.1% and least in M3 with 5.7%. The death weight variable had a primary effect on deaths. This was followed by birth weight, then farm variables. Two other factors came to the forefront to increase the survivability of the kids: deaths could be greatly reduced by providing good nutrition to the mothers in the prenatal period and offering good management, especially in the first week after birth, to obtain offspring with higher birth weights