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Faculty of Commerce, Administration and Law Faculty of Education Faculty of Humanities and Social Sciences Faculty of Science, Agriculture and Engineering Research Articles and Conference Papers Articles published on Open Access Journals and conference proceddings
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Anti-aging potential of some freshwater microalgae extracts
(University of Zululand, 2023) Sithole, Siphesihle Zamajobe.
The aging of the skin is a progressive, multi- faceted phenomenon that alters skin tissue and is impacted by both intrinsic and external causes. Age and genetics contribute to intrinsic aging, whereas ultraviolet radiation (UVR) contributes to extrinsic
aging. Intrinsic aging is a predetermined process that produces fine wrinkles, whereas long-term UVR exposure (classified as photo-aging) causes patchy hyperpigmentation, dilated blood vessels, epidermal hyper proliferation, and sunburn. Existing skincare products for anti-aging are known to include hazardous substances associated with an elevated skin cancer risk. As a result, there is a need to look for natural alternative cosmetic items. Thus, this study aimed to assess the anti- aging potential of freshwater microalgal extracts.
Freshwater samples collected from the University of Zululand environment were enriched with BG-11 and cultured under UV illumination. Out of the ten (10) pure colonies isolated from the culture and characterised through 16s RNA, Cylindrospermum alatosporum (NR125682.1) and Loriellopsis cavernicola (NR117881.1) were cultivated for biomass. Dried biomass was sequentially extracted with solvents with varying polarities namely hexane, dichloromethane (DCM) and ethanol. The phytochemical screening of the extract was conducted using GC-MS and FTIR. The antioxidant activities of the microalgal extracts were estimated by various
in vitro assays including the scavenging of 1.1-Diphenyl-2-picryl hydrazil (DPPH), 2.2- Azinobis 3-ethylbenzothiazoline-6-sulfonate (ABTS), hydroxyl (·OH) radicals and metal ion chelating, In vitro experiments were conducted to explore the inhibition of
aging enzymes, namely collagenase, elastase, hyaluronidase, and tyrosinase. UVB and UVA photoprotective activity of the microalgal extracts was also investigated. Antibacterial susceptibility testing was conducted on commensals, Propionibacterium acnes and Staphylococcus aureus.
The results obtained indicate that the extracts contained phenols and sulfhydryl groupcontaining compounds that could be responsible for certain biological activities of importance to this study. The extracts were average scavengers of synthetic radicals (IC50 values in the range from 6.5 – 48.6 μg/ml) but were potent metal ion chelators (44.3- 75.7 μg/ml). All extracts inhibited (in vitro) tyrosinase (≈ 47.87%), hyaluronidase (≈ 89.51%), and collagenase (≈ 76.67%) activities, but were poor inhibitors of elastase (≈16.43%). UVA and UVB photoprotective activity were exhibited by the extracts with L cavernicola exhibiting better UVB photoprotective activity (SPF 14.67 – 78.96).
besides, this is observed for antimicrobial activity against strains of Staphylococcus aureus (ATCC 25923 and APO25177.1) and Propionibacterium acnes Kwik-stikTM. In conclusion, C alatosporum (NR125682.1) and L cavernicola (NR117881.1) possess
the potential to be exploited as anti-aging agents.
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Indium-based thiospinels via solid-state pyrolysis of metal-organic precursors for water splitting and supercapacitance
(University of Zululand, 2023) Mzimela, Zimele N. T.; Revaprasadu, Neerish and
Khan, Malik D.
The ever-increasing global energy demands emanating from population growth and technological advancements have propelled the research community into modelling plausible breakthroughs in the fabrication of electrochemical energy storage and conversion technologies with improved performances. As a result, the past few years have witnessed significant developments in the synthesis of electrode materials with refined electrochemical activities for water splitting and supercapacitance applications. The work outlined in this thesis focuses on the synthesis and evaluation of various indium-based thiospinel nanomaterials for enhanced electrochemical energy applications. Firstly, a comparative evaluation of the energy application capabilities of bare and oleylamine-capped NiIn2S4 nanosheets fabricated from dithiocarbamate and xanthate molecular precursors is outlined. Experimental results showed that the best energy storage activities were achieved with NiIn2S4 synthesized from the xanthate mixture through the colloidal route, which presented the highest Csp of 40 F/g at a current density of 0.5 A/g. In terms of electrocatalysis for water splitting, the highest performance was observed for NiIn2S4 synthesized from the xanthate mixture through the solventless thermolysis route, which presented an HER performance with an η of 138 mV at 10 mA/cm2 and a Tafel slope of 118 mV/dec. In terms of OER performance, an η of 382 mV at 10 mA/cm2 was obtained along with a Tafel slope of 145 mV/dec. Furthermore, the scalable fabrication of compositionally-tuned Ni1-xCoxIn2S4 solid solutions through the solventless thermolysis approach is outlined. All the alloyed nanomaterials outperformed the parent compounds in terms of both supercapacitance and water splitting applications. The best OER electrocatalytic performance was obtained when x = 0.6, which displayed an overpotential of 340 mV at 10 mA/cm2 along with a Tafel slope of 87 mV/dec. In terms of HER, the highest performance was obtained when x = 0.2, which reached an overpotential of 110 mV and a Tafel slope of 176 mV/dec. For supercapacitance applications, the nanoparticles synthesized at x = 0.8 yielded the highest specific capacitance of 118 F/g at 1 A/g, along with a maximum power density of 3450 W/kg at an energy density of 2.4 Wh/kg. The work also dwells into the amplification of the electrochemical properties of MnIn2S4 through the fabrication of Mn0.5M0.5In2S4 (where M= Ni/Co) solid solutions/alloys via the solventless thermolysis of compositionally-tuned xanthate precursors. Experimental results showed that the Ni2+ and Co2+-modified MnIn2S4 outperformed pure MnIn2S4 for both water splitting and supercapacitance applications. Overall, Mn0.5Co0.5In2S4 displayed the best electrocatalytic water splitting and supercapacitance activities amongst all the synthesized nanomaterials. We further describe the synthesis of Cd1-xZnxIn2S4 composites and their subsequent evaluation for electrochemical water splitting and supercapacitance applications. Structural analyses revealed the formation of cubic and hexagonal CdIn2S4 and ZnIn2S4 thiospinels with the Fd3m and P63mc spacegroups, respectively. Furthermore, a range of stoichiometric nanostructured composite materials, whose diffraction patterns are located between those of the two thiospinels were formed between x = 0.2 and x = 0.8. Morphological evaluation showed the formation of nanosheets. All alloyed materials displayed improved supercapacitive properties, with Cd0.2Zn0.8In2S4 achieving the best results. In terms of electrocatalytic hydrogen generation, the alloyed materials displayed lower capabilities than the parent compounds. Evidently, the ternary thiospinels, solid solutions and composite nanomaterials displayed improved performances for water splitting and supercapacitance applications. This is primarily due to the synergistic effects arising from the influence of different elements. Other factors, such as the morphology proved to play a significant role in the suitability of the materials for electrochemical water splitting and supercapacitance.
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Modelling the effect of ventilation on the concentration and distribution of radon in closed environments
(University of Zululand, 2023) Mngonyama, Sifiso; Ntshangase S.S. and
Lindsay R.
Epidemiological studies show that radon (222Rn and 220Rn) is the second most important cause of lung cancer after smoking. Prolonged exposure to high levels of this radioactive gas in various indoor environments is linked to multiple lung cancer-related deaths around the world. It was classified as a human carcinogen by The International Agency for Research on Cancer. One of the most effective techniques used to mitigate radon is adequate ventilation, which can be natural (e.g., natural winds) or mechanical (e.g., fans). Recently, Computational Fluid Dynamics (CFD) has become an efficient and powerful tool for studying radon concentration and distribution in ventilated environments. This is mainly because these codes are time and cost-effective. The current work aimed to study the effects of natural ventilation in the Huguenot second tunnel and mechanical ventilation in the Steenkampskraal monazite mine on the concentration and distribution of radon using a CFD package called ANSYS FLUENT based on realistic values for the radon exhalation and ventilation rates. The radon measurements were conducted at three points along the tunnel and two points in the mine using a combination of the RAD7, Airthings, and Electret Ion Chambers (EICs). The exhalation rates in the tunnel were measured with EIC flux monitors, and in the mine, it was measured using the accumulator method. Additionally, the wind speed and direction in both environments were measured with an anemometer and wind vane. These measurements were conducted in the tunnel in July 2021 (winter) and November 2021 (spring). In the mine, measurements were collected in August 2021. During the CFD analyses, two setups (or cases) were considered for each geometry (mine or tunnel). Additionally, for the tunnel in each case, two sets of simulations were conducted, one for July and one for November, each based on measurements of these respective months. For tunnel Case 1, the exhalation distribution in the walls was based on an average, and in Case 2, it was based on the tunnel geology. Whereas for the mine, Case 1 had no ventilation, and Case 2 had ventilation. Various approximations were made to simplify these models (e.g., simplified geometry and constant wind directions). The tunnel simulation for both Cases and months showed that the 222Rn concentration increases in the flow direction and that the levels depend on the exhalation rate, tunnel geometry (e.g., length), and natural wind velocity (or wind speed and magnitude). This behaviour was further supported by the measurements, which agreed with the simulations, with some relative deviation as low as 4%. This suggested that the tunnel model can be used in future works with only minor improvements. On the other hand, the simulation for the mine with no ventilation showed that the 220Rn concentration decreases exponentially from the source wall's normal direction towards the centre, a behaviour noted in the literature. This highlighted the importance of monitoring points for representative values when studying 220Rn. When there was mechanical ventilation, 220Rn was moderately mitigated. This was because the 220Rn distribution field changed from being inhomogeneous when there was no ventilation to being mostly homogenous when there was ventilation, which reduced the 220Rn by about half in some of the near-wall regions. This overall 220Rn behaviour was in line with the measured general behaviour and existing literature. However, there was a disagreement between the simulated and measured concentration at the monitoring points in the current work. This suggested that the mine model still needs further improvement (e.g., improved geometry).
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Relationship between inflation rate and wage rate before and after inflation targeting periods in South Africa
(University of Zululand, 2023) Okosa, Jessica Onyinyechi
The increasing number of trade unions with strong/collective bargaining power in recent times have put pressure on wage rate, resulting in rate rise in South Africa, thereby causing rate rise in inflation from both the supply and demand sides with its attendant output/productivity deterioration. Consequently, this study complements existing literature by investigating the long and short-run linear and nonlinear relationships between wage rate and inflation rate before and after inflation targeting periods in South Africa. in a sample of 170 observations spanning from 1980Q1 to 2022Q1. The study quantitative, anchored on archival design, with the data sourced from the World Development Indicators (WDI) and the South African Reserve Bank (SARB) It employed the linear and the nonlinear autoregressive distributed lag (LARDL & NARDL) estimation techniques in the analysis to test these objectives. The findings made in this study have both short-run and long-run implications.
This study found a positive linear and nonlinear relationship between inflation and wage rate in South Africa for the period under investigation. This implied that although both indicators significantly raise each other during the short-run and long-run, the magnitude of the impact of inflation on wage rate was higher than that of wage rise on inflation. Therefore, higher rates of inflation caused workers/trade unions to demand for higher wages and not vice versa. Hence, the high inflation rate is more of demand-pull rather than supply/cost-push. This study also found a non-persistent inflation rate in the long-run. This implied that adaptive expectation, rather than rational expectation, is the main driver of economic agents’ price setting behaviour. This assertion was further strengthened by significant positive impact of the log of bank rate on inflation in the short-run and long-run. Moreover, high productivity was found as a strong panacea for rising wage rate and inflation rate, whereas the adoption of inflation targeting from the first quarter of the year 2000 in South Africa emitted no significant impact on the wage-inflation nexus. This was attributed to a credit crunch following the 2007/08 global financial crisis that led to policy failures and, hence, the inability of the monetary policy rate to control wage rate.
The negative impact of the cumulative negative changes in wage rate on inflation implies that, over the long-run, negative changes in unit labour costs had a marginally stronger dampening effect on inflation relative to a positive change, which in relative terms has a marginally smaller positive effect. Hence, there was weak evidence of an asymmetric/nonlinear impact of wage rate on inflation rate, and vice versa, in the long-run with no short-run nexus. This implied that positive and negative changes in the two indicators are more likely to have a trade-off with each other in the long-run than during the short-run.
Finally, the findings from the last objective of this study relating to the nature of the relationship between inflation, wage growth and productivity before and after the inflation targeting eras in South Africa revealed that the downward nexus among inflation, wage rate and bank rate during the early 1980s could be attributed to structural transition to quantitative approach to monetary policy in 1985. Moreover, high volatility recorded among productivity, inflation rate and wage rate in 2020 could be attributed to the structural shock of the COVID-19 pandemic. Based on these findings, the study recommended that government should reduce the cost of governance to keep inflation low, improve productivity through market liberalisation and tax holidays, and incentives to firms in order to keep wage rate and inflation rate low. It is also recommended that capital and money markets reform be done in order to make inflation more responsive to monetary aggregates, and financial system be liberated to cushion the effect of credit crunch that might arise from financial crisis. The findings that emerged in this study have both short-run and long-run implications. The short-run implications included rising inflation, high wage differentials among workers and job loses especially among private establishment. the long-run implications included policy conflicts structural collapse, institutional failures and high tax liability in the future as a contractionary fiscal policy mechanism to cushion demand pull-inflation.
OKUHUNYUSHWE NGOLIMI LWESIZULU
ISIFINGQO
Ukwenyuka kwamanani ezinyunyana ezinamandla okuxoxisana ngokuhlanganyela ezikhathini zakamuva nje, kuye kufake ingcindezi ekukhuphukeni kwezinga lamaholo eNingizimu Afrika. Ngaleyo ndlela kubangele ukwehla kwamandla emali kuze kukhuphuke kuzo zombili izinhlangothi zokuhlinzeka nezidingo kanye nokwehla komkhiqizo. Ngakho-ke, lolu cwaningo luhambisana nezincwadi ezikhona ngokuphenya ubudlelwano obude nobufushane obulandelanayo nobungaqondile phakathi kwezinga lomholo kanye nezinga lokwehla kwamandla emali ngaphambi nangemuva kwezikhathi eziqondiswe ukwehla kwamandla emali eNingizimu Afrika. Esampulini lokubhekwa okuyi-170 kusukela ngo-1980Q1 kuya ku-2022Q1. Imininingwane ithathwe kwi-World Development Indicators (WDI) kanye neSouth African Reserve Bank (SARB) kanti okuqondile nokungaqondile kubambezela ukusatshalaliswa (LARDL & NARDL) kwamasu okulinganisa asetshenziswayo ukuze kufezwe lezi zinhloso. Okutholakele kulolu cwaningo kunemithelela yesikhathi esifushane neyesikhathi eside.
Lolu cwaningo luthole ubudlelwano obuhle bokuqondile nokungaqondile phakathi kokwehla kwamandla emali nezinga lamaholo eNingizimu Afrika ngesikhathi sophenyo. Lokhu kuveza ukuthi nakuba izinkomba zombili ziphakamisana kakhulu ngesikhathi esifushane nangesikhathi eside, ubukhulu bomthelela wokwehla kwamandla emali, ezilinganisweni zamaholo bukhulu kunalelo lokwenyuka kwamaholo ekwehleni kwamandla emali. Ngakho-ke, amazinga aphezulu okwehla kwamandla emali abangela abasebenzi/izinyunyana zabasebenzi ukuba zifune ukukhushulelwa amaholo hhayi ngokuphambene nalokho. Ngakho-ke, izinga eliphezulu lokwehla kwamandla emali liwukudonseka kokufunwa kakhulu kunokuletha/ukucindezela izindleko. Lolu cwaningo luphinde lwathola izinga lokwehla kwamandla emali elingaphikeleli ngokuhamba kwesikhathi. Lokhu kusho ukuthi ukulindela okuguquguqukayo kunokulindela okunengqondo, loku kuyinhloko yokuphatha ukuhlelwa kwentengo ngama-ejenti ezohwebo. Lokhu kugomela kuphinde kuqiniswe umthelela omuhle werekhodi lesilinganiso samabhange ekukhuphukeni kwamandla emali esikhathini esifushane nangesikhathi eside. Ngaphezu kwalokho, ukukhiqiza okuphezulu kutholakale njengekhambi eliqinile lokwenyuka kwezinga lamaholo kanye nezinga lokwehla kwamandla emali, kuyilapho ukwamukelwa kokwehla kwamandla emali okuqondiswe kwikota yokuqala yonyaka wezi-2000 eNingizimu Afrika akuzange kube nomthelela omkhulu ekuxhumaneni nokwehla kwamandla emali kwamaholo. Lokhu kudalwe ukushoda kwezikweletu kulandela inhlekelele yezimali emhlabeni wonke ka-2007/08 eyaholela ekuhlulekeni kwenqubomgomo, yingakho nokwehluleka kwezinga lomgomo wezimali ukulawula izinga lamaholo.
Umthelela ongemuhle wezinguquko ezingezinhle ezinqwabelene ezilinganisweni zamaholo ekukhuphukeni kwamandla emali, kusho ukuthi, ngokuhamba kwesikhathi eside, izinguquko ezingezinhle ezindlekweni zabasebenzi zinomphumela odambisa kancane ukwehla kwamandla emali uma kuqhathaniswa noshintsho oluhle, okuyinto ngokwemibandela inomphumela omuhle kodwa omncane. Ngakho-ke, kunobufakazi obubuthakathaka bomthelela ongalingani/ongaqondile wesilinganiso samaholo esilinganisweni sokwehla kwamandla emali futhi okuphambanayo, esikhathini eside ngaphandle kwe-nexus yesikhashana. Lokhu kusho ukuthi izinguquko ezinhle nezimbi kulezi zinkomba ezimbili maningi amathuba okuthi zibe nokuhwebelana ngokuhamba kwesikhathi kunangesikhathi esifushane.
Okokugcina, okutholwe enhlosweni yokugcina yalolu cwaningo mayelana nesimo sobudlelwane phakathi kokwehla kwamandla emali, ukukhula kwamaholo kanye nokukhiqiza ngaphambi nangemva kwezikhathi eziqondiswe ekwehleni kwamandla emali eNingizimu Afrika kuveza ukuthi ukwehla kokwehla kwamandla emali, izinga lamaholo kanye nezinga lamabhange ekuqaleni ngowezi-1980 kungathiwa kungenxa yoshintsho lwesakhiwo endleleni yokulinganisa yenqubomgomo yezimali yangowezi-1985. Ngaphezu kwalokho, ukuntengantenga okuphezulu okurekhodiwe phakathi kokukhiqiza, izinga lokwehla kwamandla emali kanye nezinga lamaholo ngowezi-2020 kubangwe ukushaqeka kwesakhiwo sobhubhane lwe-COVID-19.
Ngokusekelwe kulokhu okutholakele, ucwaningo luncoma ukuthi uhulumeni kufanele ehlise izindleko zokubusa ukuze agcine ukwehla kwamandla emali kuphansi, athuthukise ukukhiqiza ngokukhululeka kwezimakethe kanye namaholide entela, nezinxephezelo kumafemu ukuze kugcinwe izinga lamaholo kanye nezinga lokwehla kwamandla emali liphansi. Kuphinde kunconywe ukuthi kushintshwe izimakethe zemali kanye nezimakethe zezimali ukuze ukwehla kwamandla emali kuphendule kangcono izilinganiso zemali, futhi kukhululwe uhlelo lwezezimali ukuze kuncishiswe umphumela wokuwohloka kwezikweletu okungase kuvele ngenxa yezinkinga zezimali.
Amagama Angukhiye: Ukwehla kwamandla emali, izinga lamaholo, ukukhiqiza, i-NARDL, iNingizimu Afrika.
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The push and pull factors influencing tourists to visit protected areas: a case of Hluhluwe-Imfolozi Park
(University of Zululand, 2023) Mzimela, Nomfundo Sinethemba; Ntshangase, S.D
Protected areas, such as national parks, are important for the conservation of wildlife and habitats, but they also offer recreational opportunities for tourists. Therefore, a better understanding of what motivates tourists to visit these areas can help park managers and tourism operators cater for their (tourists) needs and preferences, thus improving visitor satisfaction. The aim of this research conducted within the South African context was to model the key push and pull factors influencing tourists to visit protected areas, using Hluhluwe-iMfolozi Park (HiP) in KwaZulu-Natal Province of South Africa as a case. This research, therefore, based on its scope and objectives, filled a knowledge gap by formulating a statistically validated conceptual model of factors (the key push and pull factors) influencing tourists to visit protected areas.
This study used data collected from a sample of 435 tourists surveyed in key tourist sites within HiP to address the research objectives. Data analysis was conducted in two stages. The first stage of the analysis dealt with data integrity and descriptive statistics, using IBM SPSS software version 28, while the second stage tested the measurement (that is, construct validity and reliability of the instrument) and structural model using composite-based structural equation modelling involving a multivariate analytical technique implemented on WarpPLS software version 7.0.
The study discovered causal relationships between visitation satisfaction, push sub-factors (relaxation, social interaction, family togetherness, and prestige motivations), and pull sub-factors (resources, learning experience, recreational facilities, natural resources, history, and culture). Furthermore, the study assessed the key push and pull factors influencing tourists to visit HiP. The key tourists’ push factors identified in this study are relaxation and family togetherness while the key tourists’ pull factors identified are natural resources, destination resources, learning experience, history and culture. The results further suggest that demographic variables (such as gender, age, nationality, residency, employment status, and visitation satisfaction), have differentiated effects on push and pull sub-dimensions and overall push and pull travel motivation factors.
Based on the findings of this study recommendations were made to the HiP management/parks’ decision makers based on the marketing concept of identifying customer needs and satisfying them to improve services at protected areas. The recommendations were organised into themes or categories (such as the necessity for local community involvement in park management, marketing and promotion of park visits, enhancing visitor expectations, education programmes and regional context). The findings of this research contribute to the literature on tourism in protected areas and provide insights that can inform policy and management decisions in the context of sustainable nature-based tourism development.