Saudi Cultural Missions Theses & Dissertations
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Item Restricted THE IMPACTS OF OCEAN PLASTIC ON THE DYNAMICS OF MARINE POPULATIONS(University of Exeter, 2023-04-08) Alessa, Ali Sarrah A; Mueller, Markus; Townley, StuartIn this research project, a generalized plastics-predator-prey model is introduced. The model can be used to study the impacts of plastics on two trophic levels of a food chain in marine ecosystems. The work presented here is restricted to one type of functional response, which is Holling IV functional response. The work is divided into two main chapters: Chapter 3 and Chapter 4. Chapter 3 considers the impact of constant plastics on the predator and prey populations. Chapter 4 examines the impact of time-varying plastics on the predator and prey populations. Chapter 3 investigates the short-term impacts caused by plastics through analytically and numerically studying the local stability and bifurcations in 1D caused by varying the constant level of plastics in the marine environment. Our theoretical derivations of bifurcations through proving Sotomayor’s Theorems for the system agreed with numerical simulations. The chapter also shows dynamic transitions occurred by bifurcations such as Hopf, transcritical and saddle-node. Chapter 4 investigates the long-term impacts caused by time-varying plastics. Hence, the influence of periodic plastics forcing on the system is scrutinized via numerical bifurcation analysis. Bifurcation diagrams are obtained by means of MATCONT that uses continuation technique. These diagrams contain a variety of codimension one bifurcation curves and codimension two bifurcation points. It is found that chaos through torus destruction takes place when the developed model is periodically-forced. Furthermore, the bifurcation diagrams give a wide range of complex dynamics such as multiple attractors, catastrophe and chaos through a cascade of period-doublings when the developed model’s three key baseline values are varied. Moreover, we find a larger number of multiple solutions of various periods in the unforced and forced dynamics, compared to other predator-prey systems with Holling IV functional response, especially when two of the three baseline values are changed.5 0Item Restricted KsPETAse: A Potential Novel-Enzyme in The Biodegradation of PET Plastics.(Saudi Digital Library, 2023-11-14) Alsaytari, Abdulmalik Ibrahim; Ariza, AntonioPlastics have become an essential part of modern life due to their versatility, low cost and multiple uses. However, most types of synthetic plastic have a downside: they tend to last for hundreds of years before they break down and degrade, leaving behind harmful substances known as microplastics. The methods currently used to dispose of and recycle plastics have not proven to be the most ideal solutions. The lack of a highly efficient tool to solve the problem of plastic pollution and its accumulation in the ecosystem has been worrying scientists for years. The search for biodegrading organisms has emerged as a promising alternative to conventional methods of dealing with plastic waste. The discovery of the PETase enzyme system, consisting of two novel enzymes: IsPETase and IsMHETase, in the bacterium Ideonella sakaiensis, which can use PET (polyethylene terephthalate), one of the most widely produced and distributed types of plastic, as an energy source, has opened up the possibility of developing biotechnological tools that could use microorganisms to degrade and detoxify the plastic waste that has been choking the environment for years. The search for improving the functional and catalytic activities of these newly discovered classes of enzymes, as well as the search for other organisms that may have developed a mechanism for degrading plastic, is now more necessary than ever. The novel enzyme KsPETase, which holds structural similarities to IsPETase, was investigated in this study as a potential enzyme to be studied for its structural and functional properties that are expected to be resemble those of IsPETase. It was also intended for the investigation of whether it performs the catalytic functions more efficiently.66 0Item Restricted Reducing Plastic Pollution In Saudi Arabia: An Analysis Of Global Plastic Pollution Mitigation Policies And The Role Of Private/Ngo Sectors(Saudi Digital Library, 2023-09-20) Iskandarani, Ayman; Weikard, Hans-PeterPlastic contamination has emerged as a worldwide issue in the past few years as a result of the high dependence on plastic materials. Saudi Arabia is affected by this issue and has barely any adequate strategy to fight it. This study was undertaken to analyze various policy instruments that mitigate plastic pollution and to understand the potential contributions of NGO and private sector involvement in Saudi Arabia toward this issue. Thus, it raises two questions: What multi-dimensional policies are identified globally for combating macroplastic pollution, and how do they perform against social, economic, environmental, and technical criteria? To what extent can the Saudi private sector’s and NGOs’ involvement contribute to reducing macroplastic waste? This study revealed a set of policy combinations that received the highest scores in the criteria. Additionally, it is significant as it taps into various stakeholders’ perspectives, exposing underlying challenges and visions, thereby providing a comprehensive outlook on the plastic pollution problem within Saudi Arabia. The study employed a mixed-method approach, and two phases were carried out. The first phase included a literature review to identify multi-dimensional policies implemented worldwide to combat macroplastic pollution and their social, economic, environmental, and technical performances. The policy instruments were: Ban & plastic limits (Regulatory), Tax & Cash for Return (Economic), and Education & Labeling (Informational). Afterward, Multi Criteria Analysis (MCA) tables were created for each instrument. In the second phase, eight experts from the private sector and NGOs in Saudi Arabia were interviewed to understand better how their efforts might impact consumer behavior and reduce macroplastic waste. After collecting data from the interviews, quantitative and qualitative data analyses were applied. The findings from the MCA tables showed higher scores for plastic limits, cash for return, and education. Additionally, the ban instrument received the lowest score (19 out of 30) among all categories, while education achieved the highest (23 out of 30). The outcomes from the quantitative and qualitative analyses of the interviews highlighted unanimous validation by NGO sector experts for a multi-stakeholder approach to creating effective plastic pollution reduction policies. Insights from private sector experts detailed the significant role of consumer behavior, stakeholder collaboration, and a multifaceted approach to pollution reduction. Challenges identified included potential conflicts between stakeholders, hesitations in policy making, and economic barriers. Expert interviews further expanded on effective strategies, focusing on education, awareness, regulation, and the use of industrial alternatives. The responses highlighted differences in priorities between the private sector and NGOs and emphasized the importance of collective action, community integration, and government support. These findings illustrate the complex factors in the effort to combat plastic pollution in Saudi Arabia. Further steps might include examining consumers’ perspectives and existing policies toward traditional plastic materials.48 0