Cape Peninsula University of Technology
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Investigation into process parameter optimization of selective laser melting for producing AlSi12 parts using ANOV
No full textIn this study, AlSi12 alloy samples were produced via the selective laser melting (SLM) technique to produce high-density components with complex and customized parts for railway applications. Nonetheless, the production of dense samples necessitates the optimization of production process parameters. As a statistical design of the experimental method, response surface methodology was applied to optimize different combinations of SLM parameters. The outcomes were analyzed via analysis of variance (ANOVA) and signal-to-noise(S/N) ratios. The relationship between the hardness response to the process parameters (scanning speed and laser power) for determining the optimal processing conditions were examined. A hardness value of 133 HV was obtained. The process parameters were successfully optimized and the relationship between the parameters and the structures of the fabricated samples were reported
Comparative review of remote sensing methods for ocean plastic litter detection
No full textMarine ecosystems are significantly threatened by plastic litter, hence, effective detection and monitoring techniques are necessary. The identification and classification of ocean plastic litter is made possible by the development of remote sensing (RS) methods such as optical imaging, thermal infrared (TIR) sensing, hyperspectral imaging (HSI), multispectral imaging (MSI), and synthetic aperture radar (SAR). This article reviews the RS methods highlighting their unique strengths and limitations, emphasizing on their application contexts, data processing requirements, and potential integration for enhanced detection accuracy. It also investigates marine plastic characteristics such as size, specific gravity, spectral characteristics, thermal emissivity, surface roughness, and dielectric properties required for effective ocean plastic litter detection. The study shows different RS data collection methods, platforms used, applications, locations of study, data classes, dataset availability, benefits, and limitations. The raw data obtained by the various RS methods are susceptible to unwanted signals such as atmospheric conditions, cloud cover, and sunglint. Therefore, a detailed review of the different data preprocessing methods for RS data such as atmospheric correction, data fusion, noise reduction, cloud masking, sunglint correction, resampling, and image enhancement are performed. This contributes to enhancing the identification and monitoring of ocean plastic litter. The study further introduces a systematic review of existing ocean plastic litter detection methods based on RS, and shows the detailed process of data collection, preprocessing, data analysis, validation, mapping, and reporting. There are other factors contributing to the effective detection of ocean plastic litter using the RS methods such as sensor resolution, ground truth data, and classification methods which are discussed. Finally, the article investigates the sensor resolution, ground truth data, and classification methods. The study identifies significant gaps in the existing literature and recommends integrating multiple RS methods and optimizing preprocessing techniques to enhance ocean plastic litter detection
Antioxidant, anti-diabetic, and anti-inflammation activity of garcinia livingstonei aqueous leaf extract: a preliminary study
No full textDiabetes mellitus (DM) is the second leading cause of mortality globally. The increased concern for DM is due to the underlying complications accompanying hyperglycaemia, associated with oxidative stress and consequent inflammation. The investigation of safe and effective treatments for DM is necessary. In the present study, the cytotoxicity, phytochemical analysis, antioxidant capacity, anti-inflammatory, and antidiabetic effects in an aqueous extract of Garcinia livingstonei leaves were assessed. All tested extract concentrations showed no toxicity against C3A hepatocytes. Several phenolic compounds were identified using ultra-high performance liquid chromatography mass spectrometry (UHPLC-MS). The total polyphenol content was 100.9741 mg GAE/g, 16.7712 mg CE/g flavanols, and 2.3548 mg QE/g flavonols. The antioxidant capacity values were 253.4268 mg AAE/g, 192.232 mg TE/g, and 167.8724 mg TE/g for ferric reducing antioxidant power (FRAP), Trolox equivalent antioxidant capacity (TEAC), and 2,2-diphenyl-1-pycrylhydrazyl (DPPH), respectively. The plant extract significantly (p < 0.05) demonstrated anti-inflammatory and hypoglycaemic effects in a dose-dependent manner, with the α-glucosidase inhibition of the extract being higher (p < 0.05) than in the standard conventional drug (acarbose). The findings of this study revealed the potential of the constituents of G. livingstonei aqueous leaf extract in DM treatment. Further studies on the preparation and mechanisms of action of the plant in DM treatment are recommended
Linearization of newton’s second law
No full textThe geometric linearization of nonlinear differential equation is a robust method for the
construction of analytic solutions. The method is related to the existence of Lie symmetries
which can be used to determine point transformations such that to write the given differential
equation in a linear form. In this study we employ another geometric approach and we utilize
the Eisenhart lift to geometric linearize the Newtonian system describing the motion of a
particle in a line under the application of an autonomous force. Our findings reveal that
for the oscillator, the Ermakov potential with or without the oscillator term, and the Morse
potential, Newton’s second law can be globally expressed in the form of that of a free particle.
This study open new directions for the geometric linearization of differential equations via
equivalent dynamical system
Challenges in implementing corporate social responsibility: a study of SMES in South Africa’s construction industry
No full textTo date, very little research has been done on the concept of corporate social responsibility (CSR), particularly the practice of CSR within the global and local construction industry. This extends to studies identifying CSR implementation challenges affecting construction organisations. This work attempts to specifically identify CSR implementation challenges affecting small and medium-sized enterprises (SMEs) within the South African construction industry (SACI). Existing literature was used to provide an overview of the current CSR implementation challenges from both the global construction industry as well as generic business sectors guided by the St. Gallen Management Model. An empirical quantitative research approach study using an online questionnaire survey, with the data analysed using both descriptive (mean, standard deviation, etc.) and inferential (Analysis of Variance ANOVA) statistics was conducted. The findings revealed that SMEs in the SACI are affected by CSR implementation challenges related to a lack of integration in the SME culture and business objectives; Limited financial resources to undertake CSR initiatives; Lack of CSR skills and knowledge, and unstable economic conditions. In addition, novelty in the findings were importantly linked to the fact that although SEs and MEs are categorised differently in terms of their cidb grade and their upper limit of tender value range, the two groups of contractors’ experience similar CSR implementation challenges across four management levels as guided by the St. Gallen Management Model, carefully guiding future research into investigating mitigating factors pertaining to SEs and MEs
Basic circuit model of voltage source converters: methodology and modeling
No full textVoltage source converters (VSCs) have emerged as the key components in modern power systems, facilitating efficient energy conversion and flexible power flow control. Understanding the fundamental circuit model of VSCs is essential for their accurate modeling and analysis in power system studies. A basic voltage source converter circuit model connected to an LC filter is essential because it lowers the harmonic distortions and enhances the overall power quality of the micro-grid. This guarantees a clean and steady power supply, which is necessary for the integration of multiple renewable energy sources and sensitive loads. A comprehensive methodology for developing a basic circuit model of VSCs, focusing on the key components and principals involved, is presented in this paper. The methodology includes the modeling of space vector pulse-width modulation (SVPWM) as well as the direct quadrature zero synchronous reference frame. Different design controls, including the design of current control loop in the S-domain, the design of the direct current (DC) bus voltage control loop in the S-domain, and the design of the alternating current (AC) voltage control loop in the S-domain, are explored to capture the dynamic behavior and control strategies of VSCs accurately. The proposed methodology provides a systematic framework for modeling VSCs, enabling engineers and researchers to analyze their performance and assess their impact on power system stability and operation. Future studies can be conducted by using case studies and simulation scenarios to show the efficiency and applicability of the developed models in analyzing VSC-based power electronics applications, including high-voltage direct current (HVDC) transmission systems and flexible alternating current transmission systems (FACTS). The significance of this work lies in its potential to advance the understanding and application of VSCs, contributing to more resilient and efficient power systems. By providing a solid foundation for future research and development, this study supports the ongoing integration of renewable energy sources and the advancement of modern electrical infrastructure
Cardiovascular and renal oxidative stress-mediated toxicities associated with bisphenol-A exposures are mitigated by Curcuma longa in rats
No full textObjective: Curcuma longa Rhizome (CLR), due to its potent antioxidant phytochemical constituents, was investigated for its effects on bisphenol A (BPA)-induced cardiovascular and renal damage.
Materials and Methods: Sixty rats were randomly selected, and grouped as control, BPA (100 mg/ kg), BPA and CLR 100 mg/kg, BPA and CLR 200 mg/kg, CLR 100 mg/kg, and CLR 200 mg/kg for 21 days. Oxidative stress indices, antioxidant status, blood pressure parameters, genotoxicity, and immunohistochemistry were determined.
Results: Rats exposed to the toxic effects of BPA had heightened blood pressure, lowered frequency of micronucleated polychromatic erythrocytes, and decreased activities of antioxidant enzymes compared with rats treated with CLR. Moreover, administration of CLR significantly (p<0.05) lowered malondialdehyde content and reduced the serum myeloperoxidase activity. Immunohistochemical evaluation revealed significantly (p<0.05) increased expressions of cardiac troponin and Caspase 3 in the BPA group compared with the CLR-treated groups.
Conclusion: C. longa ameliorated cardiotoxic and nephrotoxic actions of bisphenol-A via mitigation of oxidative stress, hypertension, and genotoxicity
The effect of rooibos tea (Aspalathus linearis) consumption on human health outcomes: a systematic literature review
No full textRooibos tea, traditionally consumed by Indigenous populations, is naturally caffeine-free and contains unique polyphenols with strong antioxidant, anti-inflammatory and anti-hyperglycaemic properties. As such, a systematic review was conducted following PRISMA 2020 guidelines (PROSPERO ID: CRD42023467829) to evaluate the potential association between rooibos tea consumption and health outcomes. Relevant articles were searched from journal inception until October 2024 using five electronic databases (CINAHL, MEDLINE, Scopus, Web of Science Core Collection and Google Scholar) and one register (Cochrane Clinical Register of Controlled Trials). Included studies involved consumption of any rooibos tea beverage or supplement in humans 18 years or older and reported any health outcomes measured pre- and post-intervention. Following article screening and full text review, eight studies (175 participants) fulfilled the inclusion criteria and investigated the effects of rooibos consumption on biological [blood (n = 6); urine (n = 1)] and physiological [heart metrics (n = 2); muscle strength (n = 1)] health markers. Based on the included studies, the findings suggest benefits of rooibos consumption, particularly related to cardiometabolic health, with five studies supporting significant (p < 0.05) results. However, there is insufficient evidence to support the health benefits of rooibos consumption given the limited studies meeting inclusion criteria, the narrow scope of markers assessed and interstudy heterogeneity
The student voice on integrative teaching and learning of academic literacy at a South African university of technology
No full textAcademic literacy skills are universally considered as a valuable and integral part of academic development in higher education, yet they often remain peripheral to or are completely absent from many qualifications. At the presently selected institution, there is little consensus on the most effective model to design for and implement as far as academic literacy is concerned, and whether this should be embedded within core curricula, or as a stand-alone, credit-bearing subject. Conspicuously absent in conversations on this matter however, is the student voice, which is what the present study seeks to draw on. An analysis of students’ reflections on an integrated model of learning and teaching of academic literacy was evaluated, where the skills are taught within the context of an academic discipline. The academic literacy component was embedded within a single course taught in a Biotechnology qualification. Upon completion of the learning activities, ten students were interviewed, and a questionnaire was administered to a further fifteen students, to gauge feedback on the usefulness of the integrated model of academic literacy. We report that the pedagogy improved and enriched the overall learning experience. Students reflected that the approach enabled better access to Biotechnology content and made the discourse of the discipline more explicit, as they unlocked academic literacy skills, compared to if an academic literacy course was taken alone. More broadly, the study highlights the need to draw on student reflection and experiences in the design and implementation of pedagogies and the value of remaining responsive to student voices