SACM - Germany
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9655
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Item Restricted Development of a phase-field model for corrosion and degradation in bioresorbable stents(Saudi Digital Library, 2022) Harban, Ibrahim Abdullah; Döring, Daniela; Karras, IngoAccording to the World Health Organization (WHO), cardiovascular diseases—particularly chronic coronary heart disease (CHD) and myocardial infarction—are the leading causes of death in industrialized countries. In 2019, an estimated nine million people died from heart diseases, with 60% of these deaths attributable to CHD. Due to demographic change, an aging population is expected, leading to an increase in degenerative diseases and greater challenges for healthcare systems. Two treatment options currently exist for CHD: coronary artery bypass grafting (CABG), which is performed surgically and in hospital settings, and percutaneous transluminal coronary angioplasty (PTCA), introduced in 1977, where a stent is placed minimally invasively without requiring extended hospitalization. Although stent-based therapy has advantages over CABG in medical and economic terms, a recent meta-analysis shows the superiority of bypass surgery in improving 10-year survival rates, partly due to side effects of PTCA. Current research therefore focuses on bioresorbable materials for stent manufacturing, aiming to provide safer, more effective, and sustainable patient care compared to conventional permanent stents. While bioresorbable stents appear promising, their degradation behavior still leads to complications, preventing them from surpassing permanent stents at present. Ongoing projects aim to better predict corrosion processes and improve the safety of bioresorbable stents, with fracture mechanics and phase-field modeling representing promising approaches. This thesis analyzes the method of percutaneous transluminal coronary angioplasty (PTCA) and stent implantation in order to evaluate its advantages and disadvantages. The focus is on addressing the following research questions: What risks occur in percutaneous transluminal coronary angioplasty, and how can they be minimized? How can future stents be designed to optimally improve patient care?6 0Item Restricted Creating a Concept and Modelling a Lean Management Simulation Game in Plant Simulation(Saudi Digital Library, 2025) Harban, Ibrahim Abdullah; Näser, Peggy; Kober, DoreenMaterial flow technology has undergone significant development over time. While production processes were initially characterized by manual individual solutions, the introduction of mass production in the early 20th century—especially through Henry Ford’s assembly line principle—revolutionized industrial manufacturing. However, this production method also led to high inventories, long throughput times, and limited flexibility. In response to these challenges, Toyota developed the Toyota Production System (TPS) in the 1950s, which laid the foundation for Lean Management. By applying principles such as waste reduction, just-in-time production, and continuous improvement (Kaizen), more efficient and flexible manufacturing became possible. Today, Lean Production represents a global standard in industrial manufacturing, aiming at resource efficiency, quality enhancement, and delivery reliability. At the same time, material flow technology plays a crucial role in optimizing production and logistics processes, reducing costs, and strengthening competitiveness. Digitalization, especially discrete-event simulation, enables detailed analysis and optimization of material flow. Using software solutions such as Tecnomatix Plant Simulation, companies can model, simulate, and improve complex material flow systems prior to physical implementation. The aim of this thesis is to analyze the theoretical foundations of Lean Production and material flow technology, as well as their practical application in a simulation game. The focus is on evaluating the effectiveness of Lean tools such as 5S, SMED, TPM, and Poka Yoke, and on examining the influence of takt, flow, and pull principles on production performance. The results of the simulation game provide a basis for practice-oriented recommendations for implementing Lean Production in real production environments. Furthermore, the thesis investigates a simulation-based training system for conveying Lean methods. Through a simulation study, the effectiveness of optimization measures in a model factory is evaluated, aiming to derive relevant insights for improving production processes and quantifying the impact of Lean methods on material flow efficiency.10 0Item Restricted Association between Physical Activity, Sedentary Behaviors, and Sleep and Cardiometabolic Health among Adults in the Kingdom of Saudi Arabia: Establishment of the Saudi ProPASS Prospective Cohort Study(Saudi Digital Library, 2025) Alaqil, Abdulrahman Ibrahim; Caserotti, PaoloBackground: Physical behaviors such as physical activity (PA), sedentary behavior (SB), andsleep are crucial indicators of health, with insufficient PA, excessive SB, and poor sleep being linked to higher incidences of non-communicable diseases (NCDs) like cardiovascular disease and diabetes. Globally, many adults do not meet recommended PA levels, and most countries are unlikely to meet global PA targets by 2030. This issue is particularly severe in Saudi Arabia, where urbanization has led to lifestyle changes characterized by low PA, increased SB, and a rising prevalence of NCDs. Despite the significance of these behaviors, there is a lack of comprehensive data on PA, SB, and sleep among Saudi adults. The World Health Organization has flagged in particular the expansion of device-based data to under-represented counties as an urgent research need to enhance understanding of the health impacts of these behaviors. In response, the Prospective Physical Activity, Sitting, and Sleep Consortium (ProPASS) was established as an international research platform to spearhead the expansion of the evidence base and transition to wearables data based global guidelines. Initially, ProPASS focused on thigh-worn and recently ProPASS has expanded to wrist-worn accelerometry devices to collect detailed data on PA, SB,sleep, and their connections to health outcomes. Based on ProPASS methodologies, this Ph.D.study seeks to address this gap by establishing a cohort in Saudi Arabia, thereby providing crucialdata to guide public health strategies in line with Saudi Vision 2030. Objectives: This thesis aimed to establish a prospective cohort that will investigative theassociations between device measured lifestyle behavior (physical activity, sedentary behavior,and sleep time) and cardiometabolic health in a sample of Saudi adults. This thesis seeks to provide preliminary evidence of feasibility and validity of ProPASS methods within Saudi Arabia context as well as initial evidence of associations between 24-hour physical behaviors and cardiometabolichealth in this population. Method: The aims were investigated in three cross-sectional studies with adults in Saudi Arabia.The study I aimed to translated and culture adaptation for three questionnaires which were Sedentary Behavior Questionnaire (SBQ), Dietary Habits Questionnaire adapted from the Surveyof Health, Aging and Retirement in Europe (SHARE), and Preclinical Mobility Limitation questionnaire. The study II aimed to assess the feasibility and acceptability of ProPASS method in Saudi Arabia, where recruitment, acceptability, suitability, of study procedures, and Resources and ability to manage and implement the study were assessed. Lastly, study III investigated the association between physical behaviors and cardiometabolic health markers. Result: The Sedentary Behavior, Dietary Habits SHARE, and Preclinical Mobility Limitation questionnaires are ready to be used in Arabic-speaking countries (Paper I). The ProPASS protocols have a requirement rate of approximately 65% and a high completion rate of about 88%, indicating they are feasible to administer in Saudi Arabia (Paper II). Preliminary results from Study III(n=845) showed that Saudi adults spend 13.07 hours sitting, 2.01 hours standing, 1.08 hour in LIPA, 0.98 hours in MVPA, and 6.85 hours sleeping (Paper III). Conclusion:This thesis successfully established a foundational understanding of physical behaviors, includingPA, SB, and sleep, within a Saudi Arabian context. The translation and cultural adaptation of key questionnaires (SBQ, SHARE Dietary Habits, and Preclinical Mobility Limitation) have made them suitable for use in Arabic-speaking populations, filling a critical gap in tools available forthis region. The feasibility study demonstrated that the ProPASS protocols, which incorporate advanced device-based measurements, are both viable and well-received among Saudi adults, withhigh completion rates. Preliminary findings from the cohort reveal significant patterns of physical behavior, such as prolonged sitting times and limited engagement in MVPA, which are concerning given their associations with cardiometabolic health risks. These results underscore the urgent need for targeted public health strategies to address the sedentary lifestyles prevalent in Saudi Arabia, in alignment with Saudi Vision 2030. The data gathered from this research not only enriches the global understanding of physical behaviors in underrepresented regions but also provides a robust foundation for future studies aimed at mitigating the rising burden of non-communicable diseases in the Kingdom.15 0Item Restricted Appraisal of Sustainable Urban Development in Shaqra City, Saudi Arabia(Eberhard Karls Universität Tübingen, 2024) Alhomaidhi, Ahmed Abdullah; Olaf, KühneThis study thoroughly explores sustainable urban development in Shaqra City, Saudi Arabia. It examines the challenges, opportunities, and solutions needed to promote sustainability in environmental, economic, and social areas. Using thematic and interpretive analyses, the study identifies key factors shaping the city. In terms of the environment, Shaqra City can enhance sustainability by improving agricultural spaces. However, issues like the lack of systematic garbage sorting in waste management reveal the need for focused solutions. In the economic dimension, the city shows potential in family-based businesses and seasonal activities like the Red Pepper Festival. However, challenges such as high fees and operational costs hinder commercial investments. Compared to neighboring regions, Shaqra City's economic growth is relatively slow, emphasizing the need for targeted economic measures. On the social front, efforts to reduce corruption and build trust in municipal institutions show progress. Opinions about gender equality vary, but community well-being is supported by initiatives like educational campaigns and local events. Despite these efforts, challenges such as limited social community initiative and proximity to larger urban centers persist. Opportunities for environmental awareness, cultural understanding, and partnerships can address these issues. The study offers recommendations to address these challenges and harness opportunities. These include environmental conservation, economic diversification, and governance reforms. With collaboration among stakeholders, Shaqra City can progress toward a more sustainable and resilient urban future.14 0Item Restricted Bridging the gaps in mortality data and healthcare access: A novel verbal autopsy application using subnational T2DM register in Saudi Arabia.(University of Gothenburg, 2025) Alyazidi, Faleh; Hussain-Alkhateeb, Laith; Petzold, Max; Shakely, DelérAbstract Background: Diabetes mellitus is an increasingly critical health concern in Saudi Arabia, often with other comorbidities and mortality causes, such as cardiovascular disease (CVD). National sociodemographic changes entail the urgent need for reliable insights on the scale and causes of mortality in order to develop appropriate healthcare policy. Where death certification is inadequate, verbal autopsy (VA) can serve as a useful tool to fill crucial gaps in vital data. This thesis aims to explore various contextual dimensions using the validated VA method. Specifically, this thesis aims to explore the community perception of causes of death, measure the circumstantial barriers (social and health system) to accessing healthcare, assess and validate the adequacy of medical certification of cause of death at population level, and investigate the clinical and demographic factors influencing out of hospital deaths among deceased individuals with specific health conditions T2DM and CVD. Methods: Studies I-IV utilized mortality data from the T2DM register at a major hospital in Makkah City, while Study V used data from the CVD registers at two major hospitals. For the first three studies, 302 VA assessments were conducted with the deceased’s next of kin. The VA data were analyzed using the computerized InterVA-5 software, which provided probable causes of death and circumstances of mortality categories (COMCATs). Study I employed Lin’s concordance correlation coefficient (CCC) to assess the concordance between verbal autopsy causes of death (VACoD) as a presumed reference standard and family-reported causes of death. Also, the study employed multiple logistic regression to identify factors influencing community perception of causes of death. Study II applied epidemiological estimations of absolute measures and Causes Specific Mortality Fractions (CSMFs), while also using numerical and graphical assessment to describe trends and patterns in the VA data. The COMCATs were ranked across the causes of death based on their derived probabilities. Study III employed Lin’s CCC to assess the concordance between physician reviewed causes of death (PRCoD) and VACoD at the population level. Study IV employed multiple logistic regression to identify factors influencing out of hospital deaths among deceased with T2DM, while Study V focused on CVD. Findings: Study I demonstrated broad community perceptions of causes of death, with notable misconceptions related to type of death and marital status. Study II found most deaths were seen as inevitable, with the COMCATs ‘recognition’ and ‘traditions’ being identified as avoidable barriers. Study III showed moderate concordance between PRCoD and VACoD, though discrepancies were apparent in the CSMFs, particularly for the most prevalent causes. Studies IV and V uncovered that cause and year of death in addition to nationality significantly influenced out of hospital deaths, with both studies illustrating decreasing trend of out of hospital mortality. Conclusion: This thesis uncovers challenges for Saudi public health policy concerning T2DM-related mortality, identifying issues in access to healthcare, community perceptions, and medical certification. Misconceptions about mortality causes of death hamper prevention strategies, while health system and sociocultural barriers heighten latent problems. The findings underscore the requirement to enhance the medical certification, as discrepancies between PRCoD and VA data suggest challenges in current practices on population level.7 0Item Restricted Investigation of the role of Kv1.3 and Kv1.6 potassium channels in retinal ganglion cell degeneration in vitro.(Eberhard-Karls-University Tübingen, 2023-12-11) Fallatah, Azdah Hamed; Paquet-Durand, François1.0. Abstract 1.1. Introduction Organotypic retinal explants are an ideal system for identifying and studying potential treatments for retinal diseases, such as inherited retinal degeneration (IRD). In the organotypic retinal explant culture procedure, retinal ganglion cells (RGCs) usually progressively die in response to optic nerve axotomy. Previous studies connected RGC death to excessive NO/cGMP/PKG signalling. Another study showed that PKG targets Kv1.3 and Kv1.6 potassium channels, which are located in the ganglion cell layer (GCL). Others showed that Kv1.3/Kv1.6 potassium channels contribute to RGC degeneration after optic nerve crush in vivo. Interestingly, recent studies showed that PKG inhibition in retinal explants restored the viability and function of RGCs in vitro. Here, we investigated whether the direct inhibition of Kv1.3 and Kv1.6 channels with 50 nM Margatoxin (MrgX) might rescue RGCs in vitro to find a possible relationship between RGCs survival, PKG inhibition, and Kv1.3/Kv1.6 channels. 1.2. Methods For this study, cultures of organotypic retinal explants derived from post-natal day (P) 12 wild type (WT) mice were treated with the Kv1.3/Kv1.6 inhibitor of MrgX until P13 (24h) or P14 (48h). The PKG inhibitor CN238 was used to treat retinal explants at P13 (24h), P14 (48h), and P24. The rate of RGC degeneration was evaluated using both TUNEL-assay, which can label dead cells, and RNA-binding protein with multiple splicing (RBPMS) staining, which is a marker for RGCs. Furthermore, Amacrine cell (AC) staining was used to determine the protective effect of MrgX and CN238. 1.3. Results RGCs survived in vitro after 48h of culture with MrgX, RBPMS-positive cells showed a 70 % increase per mm2. On the other hand, the number of TUNEL-positive cells remained below 1,000 per mm2 in both MrgX-treated and non-treated groups. The overall percent difference in cell death between the two groups was 2%. In cultures treated with CN238, the amount of TUNEL-positive cell/mm2 dropped significantly after 24h and 48h. Cultures treated with CN238 for 10 days showed a significant increase in RBPMS-positive cells/mm2 and a significant decrease in TUNEL-positive cells/mm2. 1.4. Conclusion The inhibition of the Kv1.3 and Kv1.6 channels with 50 nM MrgX protected RGCs from the induced degeneration due to optic nerve transection in WT retina in vitro. This suggests a relationship between Kv1 channels and RGC death. In addition, the CN238-mediated PKG inhibition rescued RGCs. Together these results suggest that RGC degeneration in retinal explants following the severing of the optic nerve could be triggered by a potential new putative cell death pathway, which involves the signalling along the cGMP/PKG/Kv1 pathway.11 0Item Restricted Orthodontic treatment effect on the oral health-related quality of life, oral function, and facial aesthetics in a group of Swedish adolescents, a longitudinal study(Karolinska Institutet, 2024) Asiri, Elham; Pegelow, MarieBackground: Malocclusion is one of the most prevalent oral conditions that negatively impact patients' physiological and psychological well-being. This longitudinal research aims to investigate how orthodontic treatment affects OHRQoL in a Swedish cohort of adolescents. Material and methods: Sixty-nine patients with different malocclusions who have had orthodontic treatment at Karolinska Institutet, aged 13 to 19, participated in this study. The patients answered OHRQoL questionaries at three different times: Before starting orthodontic treatment, during, and after finishing orthodontic treatment. The questionnaire consisted of three components: Oral Health Impact Profile-14 (OHIP-14), Jaw Functional Limitation Scale-20 (JFLS-20), and Orofacial Aesthetic Scale (OES). The data were statistically analyzed using the R software package. Friedman test assessed if answers differed significantly before, during, and after treatment. Multiple pairwise tests were used to identify which time points were different. Repeated ANOVA of mean was used in sum scores over time. Results: Significant change in mean values of aesthetic sum scores of all malocclusions at three time points; baseline to during (p-value 0.02), during to after (p-value 0.01), and from baseline to after treatment (p-value 0.00). For OHIP-psychosocial impact domain, significant improvement was found when a combination of all groups was tested from baseline to after treatment. For separate questions, the following questions was significantly decreased in time point before to after treatment: OHIP_10: “Been embarrassed”, Est_03: “Your mouth’s appearance (smile, lips, visible teeth)”, Est_04: “Appearance of your rows of teeth”, Est_05: “Shape/form of your teeth”, Est_08: “Overall, how do you feel about your face, mouth, and teeth” (p-value 0.00). Est_06: “Colour of your teeth” (p-value 0.02). Conclusion: Orthodontic treatment has a positive effect on OHRQoL in Swedish adolescents, especially in the aesthetic and psychosocial domain.13 0Item Restricted Setting and Achieving Sustainable Environmental Goals in Ghadah Alsaeedi's Fashion and Cosmetic Business: A Case Study in Saudi Arabia(SRH University of Applied Sciences Berlin, 2024) Alsaeedi, Ghadah; Hessal, FranzAbstract: This study by Ghadah Alsaeedi focuses on sustainable practices in the fashion and cosmetics industries, focusing on Saudi Arabia. Findings indicate that sustainable business practices are practical in Saudi Arabia even against challenges such as complex logistics and low purchaser awareness. Thus, the paper emphasizes that such a sustainable drive can only be possible through continuous innovation and community participation. As much as it is an intelligent economic strategy, the commitment represented in the word 'sustainability' indicates a vision for the future that is ethical, environmental, and social. This research displays how sustainable practices may navigate complex industrial systems and impact future moral and responsible ones - all of which have revolutionary implications, making this an essential inquiry into the potential of sustainable practice. Aside from the valuable perspectives on the unique challenges and triumphs that mark Ghadah Alsaeedi's businesses, the study would also contribute to the discourse on sustainable business methodologies in the fashion and cosmetics industries, most especially taking into consideration the unique cultural and economic milieu of Saudi Arabia10 0Item Restricted Pushing the Boundaries of Photoconductive Sampling in Solids(Ludwig-Maximilians-Universität München, 2023-04) Altwaijry, Najd Abdulaziz; Kling, Matthias F; Fattahi, HaniehThe advent of laser-based optical tools featuring few-cycle pulses with durations of less than a hundred femtoseconds in the late 1980s enabled scientists to initiate and observe the evolution of chemical reactions. This powerful approach combined the interactions of light and matter and unleashed an unprecedented metrology concept that tracks the interactions of atoms and molecules in their natural timescales. Electron wavepacket dynamics take place in the attosecond range, a thousand times faster than molecules. In optical terms, such durations typically last less than the half-cycle duration of optical fields. Consequently, the investigation of such electronic processes necessitates measurement techniques capable of resolving the oscillations of the electric field of light. The primary objective of this thesis is to develop and advance novel field characterisation techniques based on photoconductive sampling. The first portion of this thesis addresses broadband field characterisation based on nonlinear photoconductive sampling. A theoretical analysis of current formation and localisation in solids is presented, prompting the fabrication of a heterostructured sample with the aim of enhancing the magnitude of the signal obtained from the measurement technique. A thorough proof-of-principle experiment is performed, whereby a significant enhancement in signal magnitude is established. As a consequence of signal improvement, the heterostructured sample reaches the desired stability regime earlier than its traditional bulk counterparts. Moreover, the performance of the heterostructured sample for field characterisation is compared to fused silica and benchmarked against the well-established technique of electro-optic sampling. These results pave the way towards field sampling in low pulse energy systems. The following section details broadband field characterisation based on linear photoconductive sampling by employing tailored pulses from a waveform synthesiser. Visible-ultraviolet pulses are utilised to inject carriers in a common semiconductive material (gallium phosphide), enabling the complete characterisation of a mid-infrared test field. Furthermore, the technique is validated against electro-optic sampling. When compared to electro-optic sampling, the response function of linear photoconductive sampling is concerned with the intensity envelope of the gating field, relaxing the strict requisites on the temporal phase of the gate. The demonstrated results represent a significant achievement in extending field sampling techniques beyond 100 THz and towards the visible range. Finally, a machine learning-based algorithm for denoising waveforms obtained from a laboratory setting is developed and implemented. The algorithm is based on a one-dimensional convolutional neural network, ideal for processing data presented on an evenly spaced grid. The model is compared with well-established methodologies, namely denoising via the fast Fourier transform and wavelet analysis and exhibits excellent performance, extending the repertoire of tools typically used for combating noise. The field characterisation methodologies presented in this thesis pave the way towards accessible and cost-effective field sampling techniques, enabling researchers to study field-induced electron dynamics in matter and usher in ultrafast optoelectronic signal processing towards the PHz range. In general, the field characterisation techniques presented occupy a small footprint, and the measurements take place in ambient air conditions, facilitating their integration in existing experimental infrastructures. With the aid of AI-accelerator chips, the machine learning tool developed in this thesis can be implemented during laboratory measurements as a concurrent denoising technique.19 0Item Restricted In Vitro Cytotoxic and Genotoxic Assessment of Nano Polyethylene Terephthalate Exposure on A549 Cells(University of Copenhagen, 2023-05-30) Alzaben, Mohammad; Roursgaard, MartinGlobal plastic production in 2019 amounted to 359 million tons, with the European Union contributing 17%. Plastic has caused environmental and health concerns. Nanoplastics, tiny fragments of plastic measuring less than 1μm in size, have become ubiquitous in the environment. As a result of plastic pollution and poor waste management, nanoplastics have infiltrated several ecosystems, including oceans, freshwater bodies, and even the air we breathe. Studies have linked exposure to MP/NP to adverse health effects such as Pneumoconiosis, chronic bronchitis, allergic and asthmatic reactions, and lung and digestive system cancer, raising concerns about their potential health effects. This study aims to assess two main biological adverse effects of nanoplastics, cytotoxicity and genotoxicity, on human lung carcinoma epithelial cells (A549). We chose polyethylene terephthalate (PET) because it is one of the top-produced plastic polymers. We found that NPET significantly induces ROS production and DNA strand breaks = 0.10 lesions/106 bp at the highest concentration (125 μg/ml).10 0