Catalytic pyrolysis of plastic waste to produce diesel-like fuel.

Masters Degree. University of KwaZulu- Natal, Durban.Over the years, plastic generation and usage have increased due to plastics' favourable properties for domestic and industrial purposes. Plastics are cheap to manufacture, durable, flexible, resistant to moulding and rust, amongst other properties. The diverse application of plastics in the different sectors has led to increased plastic waste and management challenges. Plastic waste management options such as recycling, incineration, and landfilling have been used; however, there are drawbacks to these options. Plastics are petroleum-based, and a lot of energy is embedded in them. Several waste to energy technologies have been researched and adopted to deal with plastic waste. Among these technologies are gasification, plasma process, pyrolysis, and incineration. Pyrolysis has emerged as the most desirable process since it significantly reduces the volume of waste, produces various high-energy products, and requires lower decomposition temperature. The process is desirable because of its flexibility. Pyrolysis parameters are manipulated to optimise the desired product yield. The process parameters include but are not limited to temperature, heating rate, residence time, particle size, and catalyst. Different types of plastics and biomass can be thermally devolatilised using the process. In the current study, catalytic devolatisation of polypropylene plastic waste through the pyrolysis process was studied. Key factors affecting the final product, i.e. temperature, feed composition, heating rate and catalysts, were reviewed. The effects of temperature and silica-alumina catalyst on the product yield and quality were investigated. A central composite design was employed for the experimental design. It was observed that increasing the catalyst at lower temperatures impacted on the liquid and solid fraction yield, the liquid fraction yield increased while the solid fraction yield decreased. The use of silica-alumina significantly decreased the process temperature. At 427 °C and 33.9% silica- lumina, an optimum liquid fraction yield of 89.95 wt.% was obtained. It was noted the liquid fraction hydrocarbons in the gasoline range. Shorter hydrocarbons (C3-C18) were predominant in the liquid oil

The influence of biophysical and socio-economic factors on the effectiveness of private land conservation areas in preventing natural land cover loss across South Africa

There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability). Biophysical and legal contextual factors had low explanatory power in the best model for the nationwide analysis (n = 5121 PLCAs). For a subset of PLCAs (n = 72) we found that effectiveness depended on the strategy they adopted to generate an income, as opposed to the amount of income itself. PLCAs that attracted high volumes of visitors to small properties to view charismatic "Big 5" wildlife were less effective in conserving natural land cover than larger, more exclusive "Big 5" PLCAs and those focused on hunting. Overall, site-specific management factors were better at explaining the effectiveness of PLCAs than biophysical factors. Our findings indicate that conservation practitioners and policy makers need to recognise the diverse goals, motivations and management models of PLCAs when considering how to support them in conserving biodiversity. Future studies could explore whether these trends hold for other proxies of biodiversity conservation, beyond land cover change.Peer reviewe

Electrocatalytic detection of l-cysteine using molybdenum POM doped-HKUST-1 metal organic frameworks

Glass carbon electrodes (GCE) were modified with metal organic frameworks (MOFs) containing molybdenum polyoxometallates (Mo POMs) in a copper benzene tricarboxylate framework (HKUST-1). The Mo POMs were introduced via one-pot synthesis (Mo2) and post-synthetic modification (Mo1) techniques. The electrode modifiers were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal analysis. The modified electrodes’ oxidation capacity toward L-cysteine was studied. Mo POMs significantly improved electron transfer kinetics compared to the bare GCE. The best Mo POM doped electrode (Mo1-GCE) had a catalytic rate constant of 2.2 × 104 M−1 s−1 and a limit of detection of 3.07 × 10−7 M. Under the employed experimental conditions, the detection response for L-cysteine was very fast (within 0.1 s) for all the modified electrodes and selective toward L-cysteine in the presence of other amino acids

Effectiveness of private land conservation areas in maintaining natural land cover and biodiversity intactness

CITATION: Shumba, T. et al. 2020. Effectiveness of private land conservation areas in maintaining natural land cover and biodiversity intactness. Global Ecology and Conservation, 22:e00935, doi:10.1016/j.gecco.2020.e00935.The original publication is available at https://www.journals.elsevier.com/global-ecology-and-conservationPrivate land conservation areas (PLCAs) are increasingly looked to for meeting the deficit left by state-owned protected areas in reaching global conservation targets. However, despite the increasing extent and recognition of PLCAs as a complementary conservation strategy, little research has been done to quantify their effectiveness; a critical consideration if they are to be counted towards international biodiversity conservation targets. The long history of PLCAs in South Africa provides an interesting case study to address this knowledge gap. Here, we quantified the effectiveness of South African PLCAs by comparing losses in natural land cover and biodiversity intactness within PLCAs with different levels of protection to that of unprotected control points. Points within PLCAs were matched with unprotected control points to test the prediction that if PLCAs offer effective protection, losses in natural land cover and biodiversity intactness would be significantly lower within their boundaries in comparison to unprotected controls exposed to similar conditions. Consequences of natural land cover loss on biodiversity intactness were thus assessed, thus advancing standard approaches for quantifying effectiveness. Between 1990 and 2013, PLCAs lost significantly less natural land cover (3%) and biodiversity intactness (2%) than matched unprotected areas (6% and 4%, respectively). Of the natural land cover lost within PLCAs, most was converted to cultivated land. Farms can support more species than other land uses (e.g. mines), a likely explanation for why losses in biodiversity intactness were less than losses in natural land cover. Contrary to the predicted pattern, effectiveness did not increase with level of protection; informal PLCAs with no legal protection had comparable natural land cover and biodiversity intactness retention to strictly protected PLCAs, with most losses recorded among PLCAs with moderate protection. This study provides the first national-scale evidence that PLCAs can be an effective mechanism for conserving natural land cover and biodiversity intactness, which is highly relevant given current discussions around their likely long-term biodiversity conservation capacity.Publisher's versio

Monitoring Cardiovascular Physiology using Bio-compatible AlN Piezoelectric Skin Sensors

Arterial pulse waves contain a wealth of parameters indicative of cardiovascular disease. As such, monitoring them continuously and unobtrusively can provide health professionals with a steady stream of cardiovascular health indices, allowing for the development of efficient, individualized treatments and early cardiovascular disease diagnosis solutions. Blood pulsations in superficial arteries cause skin surface deformations, typically undetectable to the human eye; therefore, Microelectromechanical systems (MEMS) can be used to measure these deformations and thus create unobtrusive pulse wave monitoring devices. Miniaturized ultrathin and flexible Aluminium Nitride (AlN) piezoelectric MEMS are highly sensitive to minute mechanical deformations, making them suitable for detecting the skin deformations caused by cardiac events and consequently providing multiple biomarkers useful for monitoring cardiovascular health and assessing cardiovascular disease risk. Conventional wearable continuous pulse wave monitoring solutions are typically large and based on technologies limiting their versatility. Therefore, we propose the adoption of 29.5 μm-thick biocompatible, skin-conforming devices on piezoelectric AlN to create versatile, multipurpose arterial pulse wave monitoring devices. In our initial trials, the devices are placed over arteries along the wrist (radial artery), neck (carotid artery), and suprasternal notch (on the chest wall and close to the ascending aorta). We also leverage the mechano-acoustic properties of the device to detect heart muscle vibrations corresponding to heart sounds S1 and S2 from the suprasternal notch measurement site. Finally, we characterize the piezoelectric device outputs observed with the cardiac cycle events using synchronized electrocardiogram (ECG) reference signals and provide information on heart rate, breathing rate, and heart sounds. The extracted parameters strongly agree with reference values as illustrated by minimum Pearson correlation coefficients (r) of 0.81 for pulse rate and 0.95 for breathing rate

Quantifying the effectiveness of private land conservation areas in preventing losses of natural land cover and biodiversity intactness across South Africa

Thesis (MScConsEcol)--Stellenbosch University, 2019.ENGLISH ABSTRACT: Global biodiversity conservation targets cannot be achieved by relying on state-owned protected areas (PAs) alone. Private land conservation areas (PLCAs) are one potential complementary conservation strategy. However, despite their increasing extent and recognition, little is known about their effectiveness in conserving biodiversity, or how different environmental and social-ecological factors influence their effectiveness. In South Africa, a long history of conservation on PLCAs and the diverse PLCA models provide an interesting case study to address this knowledge gap. The effectiveness of PLCAs across South Africa, and factors influencing their effectiveness, were thus quantified using losses in natural land cover (NLC) and the biodiversity intactness index (BII) as proxies. NLC was based on 1990 and 2013 national land cover maps, while BII represented a measure of the percentage of major taxa that can persist in an area given different land use scenarios. Points within PLCAs were matched with unprotected control points to test the prediction that if PLCAs offer effective protection, losses in NLC and BII would be significantly lower within their boundaries in comparison to unprotected controls exposed to similar conditions. NLC and BII losses were then compared across different types of PLCAs, with the hypothesis that legally protected PLCAs would be more effective than the informal ones. Of particular interest was also how different factors influenced the effectiveness of PLCAs in preventing losses of NLC and BII. In that regard accessibility (distance to road, distance to town, elevation and slope), rainfall, age and size of PLCAs were considered as explanatory variables. There were significant differences in losses in NLC and BII between PLCAs and matched unprotected areas. PLCAs lost 3% NLC and 2% BII between 1990 and 2013, while unprotected areas lost 6% NLC and 4% BII. These findings indicate the relative effectiveness of PLCAs, and provide insight into the implications of NLC loss on biodiversity intactness, thus advancing standard approaches for quantifying PA effectiveness. There were also significant differences in losses of NLC and BII between different types of PLCAs. However, contrary to the hypothesis, effectiveness did not depend on legal protection, as informal PLCAs were relatively more effective than some of the formally protected ones. NLC and BII losses were likely to occur at points within PLCAs that were closer to towns, further from roads, with low elevation, gentle slopes, within small and old PLCAs, and with low rainfall. This supports research on state-owned PAs, in which highly accessible areas were shown to be less effective due to higher human pressure. This study provides evidence that PLCAs are relatively effective, which is highly relevant given current discussions around their inclusion towards biodiversity targets. The study also highlights how different factors influence the effectiveness of PLCAs, which has important implications on where best to establish future PLCAs and how different management strategies and policies can be better placed to facilitate biodiversity conservation within PLCAs. The study contributes to the growing body of knowledge about PLCAs as a complementary biodiversity conservation strategy worth considering, which future studies can build upon.AFRIKAANSE OPSOMMING: Wereldwye pogings of biodiversiteit te beskerm kan nie ekslusief op beskermde gebiede (BG) wat deur die staat besit word staat maak nie. Privaat land bewaring gebiede (PLBGe) is een moontlike, komplimentêre bewaring strategie. Ten spyte van die immer-groeiende omvang en erkenning van die gebiede wereldwyd, is die mate tot wat PLBGe effektief is meestal steeds onbekend. Kennis met betrekking tot die invloed van kontekstuele sosiaal-ekologiese faktore op genoemde effektiewiteit is soortgelyk beperk. Danksy Suid-Afrika se lang geskiedenis met PLBG bewaring, sowel as sy diversiteit van PLBG instrumente, bied dié land ‘n interessante gevallestudie wat hierdie kennisgaping kan aanspreek. Hierdie studie het dus die effektiwiteit van PLBGe regoor Suid-Afria, sowel as die faktore wat daardie effektiwiteit beïnvloed, gewantifiseer, Tot daardie doeleinde het ek verliesse in natuurlike gronddekking (NG), sowel as die biodiversiteit intaktheid indeks (BII), as proksies gebruik. Die NG was gebaseer op die nasionale landbedekking kaart van 1990 en 2013 en die BII verteenwoordig die persentasie van ‘n meerderheid taksa wat in ‘n area kan voortbestaan onder verkillende landgebruike. Ek het punte binne PLBGe gepaar met kontroleer punte buite PLBGe om die voorspelling te toets dat, indien PLBG effetiewe bekserming bied, verliesse in NG and BII aansienlik laer sou wees binne hulle grense in vergelyking met onbeskermde kontroleer punte met soortgelyke omgewings. Ek het daarna NG en BII verliesse vergelyk tussen verskillende tipe PLBGe, met die verwagting dat PLBGe wat wettig beskerm word meer effektief sou wees as meer informele PLBGe. Ek was veral geïnteresseer in hoe verskillende kontekstuele faktore die effektiwitiet van PLBGe beinvloed, soos gemeet deur die vermoë van ‘n PLBG om verliese van NG en BII te voorkom. Moontlike verklarende faktore het toeganklikheid (gemeet deur afstand-tot-by-naaste-pad en –dorp, sowel as elevasie en helling), reënval, ouderdom en gebied grote ingesluit. Daar was ‘n aansienlike verskil in NG en BII verliesse tussen PLBGe en gepaarde onbeskermde punte. Terwyl PLBGe 3 % NG en 2 % BII verloor het tussen 1990 en 2013, het onbeskermde punte 6 % NG en 4 % BII verloor. My bevindings dui op die relatiewe effektiewiteit van PLBGe, bied insig oor die implikasies van NG verlies vir biodiversiteit intaktheid, en bevorder die tegniese kwantifisering van BG effektiewiteit. Daar was ook aansienlike verskille tussen NG- en BII verliese tussen verskillende kategoriee PLBGe. Teen verwagtinge was effektiwiteit egter nie afhanklik van wettige beskerming nie, aangesien informele PLBGe relatief meer effektief as sekere kategorieë formele gebiede was. NG en BII verliesse is meer gereëld gevind op punte wat nader aan dorpe en verder van paaie was, punte met laer elevasie, sagter hellings, en laer reënval, en punte binne ouer en kleiner beskermde gebiede. Hierdie resultate is ondersteunend van navorsing op staat-beheerde BG, wat wys dat meer toeganklike areas minder effektief is as gevolg van hoër mensdruk. Hierdie studie verskaf bewys dat PLBGe relatief effektief is, ‘n bevinding wat uiters relevant is vir kontemporêre besprekings rondom hulle insluiting in formele biodiversiteit teikens. Hierdie studie beklemtoon ook hoe verskeie faktore die effektiwiteit van PLBGe beïnvloed, wat belangrike implikasies het vir die optimale vestiging van toekomstige BGs, sowel as die mees gepaste besturing strategieë en beleide vir biodiversiteit bewaring in verskillende PLBGe. Die studie lewer bydrae tot die toenemede kennis van PLBGe as ‘n komlimentêre bewarings strategie.Master

Channel coding on a nano-satellite platform

Thesis (Master of Engineering in Electrical Engineering)--Cape Peninsula University of Technology, 2017.The concept of forward error correction (FEC) coding introduced the capability of achieving near Shannon limit digital transmission with bit error rates (BER) approaching 10-9 for signal to noise power (Eb/No) values as low as 0.7. This brought about the ability to transmit large amounts of data at fast rates on bad/noisy communication channels. In nano-satellites, however, the constraints on power that limit the energy that can be allocated for data transmission result in significantly reduced communication system performance. One of the effects of these constraints is the limitation on the type of channel coding technique that can be implemented in these communication systems. Another limiting factor on nano-satellite communication systems is the limited space available due to the compact nature of these satellites, where numerous complex systems are tightly packed into a space as small as 10x10x10cm. With the miniaturisation of Integrated-Circuit (IC) technology and the affordability of Field-Programmable-Gate-Arrays (FPGAs) with reduced power consumption, complex circuits can now be implemented within small form factors and at low cost. This thesis describes the design, implementation and cost evaluation of a ½-rate convolutional encoder and the corresponding Viterbi decoder on an FPGA for nano-satellites applications. The code for the FPGA implementation is described in VHDL and implemented on devices from the Artix7 (Xilinx), Cyclone V (Intel-fpga), and Igloo2 (Microsemi) families. The implemented channel code has a coding gain of ~3dB at a BER of 10-3. It can be noted that the implementation of the encoder is quite straightforward and that the main challenge is in the implementation of the decoder

Synthesis and Characterisation of Activated Carbon Obtained from Marula (Sclerocarya birrea) Nutshell

Globally, a ninth of people use polluted water sources because an estimated 300–400 Mt of waste and 90% of sewage are discharged into water bodies from industries and developing countries, respectively. The utilisation of indigenous fruit pits in producing novel adsorbents will greatly benefit in wastewater treatment. In most underdeveloped countries, activated carbon (AC) is imported at a high cost. The study was aimed at synthesising and characterisation of AC obtained from Marula nutshell. Carbonization of organic matter from Marula nutshell was carried out at 200°C, 400°C, 500°C, and 600°C. Sulphuric (H2SO4) and phosphoric (H3PO4) acids were used as activating agents at concentrations of 20–60% (v/v). Physicochemical characteristics of the AC, such as bulk density, moisture, ash, pH, and iodine number, were analyzed using standard methods. Functional groups and total carbon content were determined using the FTIR spectroscopy and Nitrogen Carbon Sulphur (NCS) analyzer, respectively. The values of carbon yield and total carbon in activated samples with H2SO4 and H3PO4 were 32.2–93.2%, 26.9–95.8%, and 46–79%, 20.8–69.8%, respectively. The pH, ash, moisture, and bulk density of activated high carbon samples with H2SO4 ranged from 2.4–6.1, 0.65–3.49%, 1.3–8.4%, and 0.42–0.62 gcm−3, respectively. Activated high carbon samples with H3PO4 had 2.7–3.2, 11.3–29.8%, 4.7–14.6%, and 0.39–0.54 gcm−3 pH, ash, moisture, and bulk density, respectively. The synthesised AC samples with 40% H3PO4 at 500°C had the highest iodine value of 1075.7 mg/g. FTIR results showed the presence of aliphatic carboxylic acid salt, inorganic nitrate (NO3−), and phosphate groups in the synthesised AC and were not significantly different (p<0.05) from commercial AC. The untreated Marula nutshell had some aliphatic hydrocarbon (alkanes), inorganic phosphate (PO43−), aliphatic ester (–COO), and aliphatic carboxylic acid salt (–C(=O)O–) groups. A novel adsorbent, AC was produced from Marula nutshell with the potential to be used in water treatment

BLE-based IoT Proximity Warning System for Guaranteeing the Operators' Safety in Outdoor Working Environments

The IoT paradigm plays a crucial role as one of the technologies that contribute towards addressing one of the most significant challenges employers have to guarantee the safety of their workers at all times. Ensuring the safety of workers at all times is especially challenging in specific working environments such as modern farms, where humans and heavy vehicles or machinery must interact and operate in unison daily. Installing efficient and accurate localization systems on remote-controlled farm machines (RCFM) in such high-risk working environments can help guarantee worker safety and prevent fatal accidents. This paper presents the preliminary results obtained from an IoT-based framework that leverages Bluetooth Low Energy technology and combines the Log-distance path loss model and fingerprint technique to estimate the distance between machinery and operators. We demonstrate how the applied method can facilitate quick position estimation, which is essential for generating warning notifications to prevent operator accidents. The experimental results presented in this paper also demonstrate the reliability of the applied approach and prompt important discussion questions to promote future works on the topic