Journals National University of Science and Technology (NUST)
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Optimization of solid state fermentation conditions for improved production of cellulases by didymella phacea
Get PDFEnzyme production by microorganisms may be improved by mutagenesis of the producing strains and/or the optimization ofconditions for production. The effective and efficient use of cellulases in industrial processes has been hampered by the highcost of the enzymes which in consequence lead to high overall production costs. This study aimed at optimizing solid statefermentation conditions using affordable susbtrates and sustainable additives for improved cellulase production by Didymellaphacea. Cellulase production during solid state fermentation of different lignocellulosic substrates and the effect of varyingphysical parameters including temperature, pH, additional supplements like nitrogen source and lactose were investigated. A188% increase in cellulase production by D. phacea was achieved using solid state fermentation of Jatropha seed cake,incubated at 30 °C for a period of 72 hours, with an initial pH of 6, peptone at a concentration of 1 g/L, lactose at a concentrationof 3.5 g/L and an additional 10% thatch grass as an additional carbon source. There was a significant difference in the increaseof cellulase production before and after the optimization process ( p< 0.05). Optimization of culture conditions may be usedas a quick, cheap and effective alternative to increase enzyme production
Soil moisture based automatic irrigation control system for a greenhouse
Get PDFWater stress continues to be a major factor that affects agricultural productivity in arid and semi-arid regions, which arecharacterized by high annual rainfall variability. Water-saving practices and sound water management strategies are urgentlyrequired to ensure the long-term viability of the agricultural industry in these regions. Automated irrigation systems providegreater control over the quantity of water applied which eventually improves water use efficiency. Thus, a new control strategyutilizing a control system made from mostly off-the-shelf electronic components was developed for controlling irrigation of atomato crop in a greenhouse. The newly designed soil moisture-based automatic irrigation controller (SMAIC) managed waterapplication using moisture sensors whereby data pertaining to soil moisture was used for the prediction of irrigation timing.SMAIC saved water by up to 74% compared to local farmer practice for greenhouse tomatoes. For all the treatmentsimplemented, the yield was not significantly different. Irrigation water use efficiency (IWUE) was significantly higher in theSMAIC treatment
A comparative study of RSM, ANN and ANFIS models for predicting circuit Thevenin voltage
Get PDFManual reduction of complex circuits using the conventional Thevenin’s theorem is a time consuming, laborious, and prone-to-mistakes task. Computational intelligence-based techniques have been successfully used in the prediction of process variables, albeit in fields other than circuit reduction. It is therefore necessary to test the suitability of these computational intelligence techniques in circuit analysis, for the elimination of the highlighted challenges of the Thevenin’s theorem. This research paper presents a comparative study of the Response Surface Methodology (RSM), Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System models for predicting the circuit Thevenin voltage. The Taguchi orthogonal array has been utilized in designing the experiment with three levels for each of the three control resistor variables. The Levenberg-Marquardt training algorithm has been implemented in the ANN modelling. Based on the Mean Absolute Percentage Error (MAPE), the ANN and RSM predicted values have been compared to each other. Research results show that the RSM, ANN and ANFIS models have prediction accuracies of 90.13%, 93.35% and 95.33%respectively, in predicting circuit Thevenin voltage. The results show that ANFIS has a higher prediction accuracy of 99.86% whenusing training data set. Based on the Student’s t-test, the research revealed that the mean values of RSM and ANN predicted Theveninvoltages are not significantly different at p < 0.05. The results are a clear exhibition of the superiority of ANN and ANFIS over the RSMmodel in circuit Thevenin voltage estimation. Based on the outcome, it is concluded that computational intelligence-based techniquescan be reliably used in circuit reduction
Guest Editors List Vol. 15 (2020)
No full textThe Zimbabwe Journal of Science and Technology, thank the Guest Editors and Reviewers for ZJST Volume 15 (2020)
Parasitic infestations in houseflies and soils collected from garbage dumps in parts of Ijebu-North, Ogun State Nigeria: A cross-sectional study
Get PDFOpen defecation and indiscriminate disposal of waste is a common practice and has been highlighted as a risk factor promoting transmission of gastrointestinal parasiteshence, we investigated the prevalence of parasites in Houseflies (Musca domestica) and soil samples from garbage dumps in Ijebu-North, Ogun State, Nigeria, where such data is non-existent. Flies were collected using baited traps and approximately 100g of surface soil were collected from the garbage dumps in the study area. Standard flotation and sedimentation techniques were used to process collected soil samples, including external and internal contents from Musca domestica (M. domestica). Isolated parasites were identified under a binocular microscope. Our findings showed that all the houseflies examined were infested with at least one kind of parasite on either external or internal surfaces. A total of 328 (78.8%) of the flies were infested with Taenia sp., followed by 296 (74.0%) for Ascaris lumbricoides, 200 (48.1%) for hookworms, and the least was 64 (15.6%) for Toxocara canis. There were significant differences in the proportions observed across the different garbage dumps in the study area for Hookworm (p=0.048), Fasciola sp. (p=0.002) and Toxocara canis (p=0.033). On their internal surfaces by location, Oru had the highestprevalence for all the parasites except for Hookworms, Toxocara canis, Strongyloides stercoralis and Trichuris trichuria.Significant differences were observed across the garbage dumps in the study area and Hookworm (p = 0.015) and Strongyloides stercolaris (p = 0.014). Similarly, at least one kind of parasite was recovered from all the 32 soil samples examined, with Taenia sp. (90.0%), Ascaris lumbricoides. (83.3%) and Hookworms (60.0%) been the most common parasites. This study highlights animportant issue of gross environmental contamination with parasite eggs/larvae across garbage dumps which requires prompt clearing of garbage dumps and proper sanitization to prevent disease epidemics
Repeatability of ultrasound parameters in measuring blood flow in the lower limb arteries of asymptomatic diabetic patients with earlystage peripheral artery disease
Get PDFThe objectives of the study were to i) To determine the repeatability of ultrasound parameters in measuring lower limb bloodflow in diabetic patients with early-stage peripheral artery Disease (PAD) and ii) To determine whether any differences independent variables between sessions are significant or meaningful. Ultrasound parameters consisting of peak systolic velocity(PSV), pulsatility index (PI), resistive index (RI) and vessel diameter inner to inner (VDI) were assessed for repeatability inmeasuring blood flow in the popliteal arteries (PA), anterior tibial arteries (ATA) and posterior tibial arteries (PTA) of 10asymptomatic Black-African diabetic patients [3 males, 7 females; mean age - 49.5 (13.8) years; mean glycated haemoglobinlevels (HbA1c) - 5.9 (0.7)%; mean Ankle Brachial Index (ABI) 1.1 (0.1)and median Body Mass Index (BMI - 29.5 (24-33.7)] withearly stage peripheral artery Disease (PAD). Within and between sessions reliability intraclass correlation coefficients [ICC],percentage coefficient of variation [%CV]), measurement error (standard error of measurement [SEM] and smallest detectabledifference [SDD] were calculated for Ultrasound parameters which include peak systolic velocity (PSV), resistive index (RI),pulsatility index (PI), and vessel diameter inner to the inner (VDI) to establish their repeatability in measuring blood flow in thepopliteal arteries [PA], anterior tibial arteries [ATA] and posterior tibial arteries [PTA] of diabetic patients with early-stageperipheral artery disease [PAD]. Paired t-tests were performed and effect sizes calculated to establish if the differencesbetween sessions were significant or meaningful. PSV, PI and RI showed very good (ICC ≥0.8; 0.6 – 0.9, 95% CI) to excellent(ICC ≤1.0; 1.0 -1.0, 95% CI) reliability and acceptably low variability (≤5.6%CV) both within and between sessions. The SEMwas only high for VDI-PTA (SDD = 13.6%). PSV, PI and RI were repeatable in measuring blood flow in the lower limbs ofdiabetic patients with early-stage PAD
The electronic human resources management effectiveness link: a survey of private security industry firms in Zimbabwe
Get PDFThis study investigated the link between implementation of electronic human resources management practices andeffective human resources function in the private security sector in Zimbabwe. The research evaluated the effectiveness ofelectronic human resources practices on organisational performance, quality of human resources service, operationalefficiency and the involvement of human resources in the business The post positivist paradigm was adopted for this crosssectional quantitative study, employing a deductive approach and mono method quantitative method as methodologicalchoices. 18 research participants were selected from 3 security companies that had implemented electronic humanresources management practices. Close ended questionnaires were used in data collection and SPSS software used fordata analysis. Electronic human resources management practices were found to have an impact on effective humanresources management performance for quality of human resources management service delivery, and operationalperformance with respect to cost and time saving. No significant impact on the strategic involvement of human resourcesmanagement and organisational performance were identified. Challenges of implementing electronic human resourcessystems were found to include high cost concerns in licensing fees, maintenance and training expenses, and alignment tothe business needs. Implementation of electronic human resources management was pointed out to require a change ofmanagement strategy which proved difficult to apply due to lack of support from senior management
Improvement of low-quality diesel through the use of biodiesel
Get PDFThe transportation of petroleum diesel, petrol and jet fuel using the same pipeline lead to the formation of an off-specification productknown as the interface. The interface cannot be used on its own as it does not meet the quality specifications. It should be blendedwith a product of higher quality. Failure to blend the interface results in loss of the product and costs will arise that are associated withits disposal. In this paper, the authors examine the use of jatropha biodiesel to improve the quality of the interface. The tests wereperformed using the American Society for Testing and Materials (ASTM) methods. Jatropha biodiesel was used since it is beingproduced locally. Blending ratios of 3%, 5% and 7% interface were used and the biodiesel was found to have average flash pointvalues of 138 oC, 135 oC and 132 oC respectively. These values are greater than 130 oC which is the minimum expected value. Thesulphur content and acid number improved indicating that biodiesel can be effectively used to improve the quality of petroleum diesel
Disinfection of Escherichia Coli in water using moderate electric and magnetic fields
Get PDFBacteria play a key role in both human health and disease. One of the most prevalent harmful bacteria is E. coli which is responsible for several illnesses ranging from diarrhea, stomach cramp and fever. In this work we explore the application of moderate electric or magnetic fields for treating distilled and deionized water that is contaminated with E. coli. We found that moderate alternating current (AC) electric fields (10 V/cm to 1kV/cm) and moderate static magnetic fields (10 mT to 65 mT) can significantly inactivate E. coli by up to 90% or more. This provides the possibilities of developing a low cost and a practical bacteria inactivation technique using electric or magnetic fields.