United Arab Emirates University
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BARRIERS TO THE ADOPTION OF CROSS LAMINATED TIMBER FOR MID-RISE RESIDENTIAL BUILDINGS IN UAE
Get PDFBuildings consume about 40% of the total annual energy produced globally, with significant energy usage across different life cycle stages, including construction and operational phases. The energy associated with the construction of buildings is substantial due to the energy required for the manufacture of materials and products. This underscores the need for stakeholders in the building industry to find construction materials and systems with low embodied energy. In the pursuit of low-energy materials, massive timber products, such as cross-laminated timber (CLT), are gaining popularity in mid-rise buildings around the world. The development of CLT, which boasts excellent load-carrying capabilities, has enabled timber to be used in taller and more complex structures. Research and development in massive timber products have advanced to the point where their environmental, economic, and social benefits surpass those of traditional construction materials. Many mid-rise buildings constructed in Europe, America, Canada, and Australia have successfully utilized massive timber construction. However, no such buildings have been constructed in the UAE yet. This study aims to investigate and identify the barriers to adopting CLT as a building material and construction system for mid-rise buildings in the UAE. The methodology follows a two-step process including a quantitative and qualitative approach. A quantitative environmental impact assessment of CLT transportation evaluates its feasibility in terms of transportation costs. Additionally, a qualitative approach is used to study stakeholders\u27 behavior towards CLT construction through a comprehensive questionnaire survey and conversational interviews, with the responses analyzed to identify patterns and themes. The results reveal the existing barriers in the construction industry for adopting CLT. Strategies required to promote its adoption are further discussed. This study will aid future research in addressing the barriers to constructing mid-rise buildings using CLT in the UAE
EXPERIMENTAL INVESTIGATION OF VARIOUS HYDROGEN KNOCK LIMIT EXTENSION STRATEGIES ON A HYDROGEN-GASOLINE DUAL FUEL SPARK IGNITION ENGINE
Get PDFHydrogen is a clean and carbon free substitute with the ability to significantly cut down the harmful emissions while enhancing the energy efficiency of internal combustion engines (ICE) typically powered by conventional fossil fuels. Hydrogen is the most abundant element which can be easily obtained from sources like water and biomass. The wide flammability range and high laminar flame velocity outstands hydrogen from other fuels. However, hydrogen fueled engines are more prone to abnormal combustion like knock and backfire due to its low ignition energy and high adiabatic flame temperature. To avoid backfire, several well-developed approaches have been reported. Unlike backfire, combustion knocks are more severe and difficult to control. Thus, a study on extending the hydrogen on extending the hydrogen knock limit is of great importance. The main focus of this thesis is to investigate various strategies that helps in extending hydrogen fraction while avoiding the engine knock in spark ignition engine operating under hydrogen–gasoline dual fuel combustion where conventional gasoline is replaced drastically by hydrogen. The first part of the thesis investigates the hydrogen–gasoline combustion in a Ricardo single cylinder SI engine with hydrogen manifold induction and gasoline direct injection. A range of experimental trials were conducted to investigate the original knock limit, performance, combustion and emissions under various engine speed and gasoline injection quantity. Hydrogen exhibited superior results than pure gasoline which are more pronounced at low engine speed with the highest brake thermal efficiency of 27.48% at 1000 rpm. Apart from that, the highest gasoline injection quantity showed the least cyclic variation which is mainly due to the concentration of gasoline near the vicinity of spark plug. The result showed that at default configuration for the best combination (1000 rpm and 6 mg gasoline) a hydrogen knock limit of 8 LPM was achieved. Next a comparison study between pure gasoline and hydrogen–gasoline mixture knock was conducted. The outcomes exhibited that the hydrogen enrichment results in severe knock. The combustion knock are usually inherited with high cylinder pressure and abnormal heat release rate. The heat release rate at knocking conditions were 151.2 and 128.53 J/deg for the 25% and 12.5% hydrogen flow rate compared to 86.86 J/deg for pure gasoline. Following this, several methods that can be implemented to an existing engine on extending the hydrogen knock limit was investigated. To facilitate these studies, change in spark timing, intake air temperature and pressure, and dilution with CO2 gas and fuels possessing high latent heat of vaporization were adopted. A retardation in spark timing showed an increased hydrogen flow rate. The result showed that a hydrogen flow rate of 14 LPM was achieved from the original limit of 8 LPM when the spark timing retarded from 12° CA to 4° CA BTDC. This is due to the extension of combustion process to the expansion stroke with reduced the cylinder pressure and temperature. Moreover, a change in intake air pressure and temperature also facilitated the extension in hydrogen knock limit. An increase in intake air pressure and decrease in the intake air temperature allowed the extension of hydrogen knock limit. A hydrogen flow rate of 18 LPM was achieved at an intake air pressure of 112 kPa at 4° CA BTDC. Furthermore, hydrogen knock limit was influenced greatly by the addition of ethanol and methanol fuels. The highest hydrogen flow rate of 16 and 18 LPM was obtained for 50% volume proportions of ethanol and methanol, respectively. This increment was due to the high latent heat of vaporization of alcohol which provides a charge cooling effect during combustion. Apart from these strategies, dilution of combustible mixture with CO2 gas also extended the hydrogen knock limit. A maximum hydrogen flow rate of 16 LPM was achieved which can be attributed to the high heat capacity and inert nature of CO2 gas. Further, the research outcomes can be extended to wide applications in the field of automotive and aerospace. These approaches can be implemented on jet, stationery and gas engines with less dependency on fossil fuel-based products
POLICYMAKER’S PERSPECTIVES AND STUDENT EXPERIENCES OF BULLYING AT SCHOOLS IN THE UAE: A MIXED-METHOD APPROACH
Get PDFBullying is a significant issue in schools worldwide, including in the UAE. This dissertation aims to explore the dynamics of school bullying and improve anti-bullying interventions through a mixedmethod approach. The primary goal is to investigate current anti-bullying efforts in the UAE and identify a comprehensive framework for school-based bullying intervention, considering policymaker perspectives and student experiences. The study includes a systematic scoping review, qualitative studies with policymakers, a SWOT analysis of Abu Dhabi\u27s anti-bullying approaches, and a crosssectional survey of students\u27 perceptions, attitudes, and awareness in Al-Ain City. These methods provide an integrated view of bullying in the UAE by incorporating diverse perspectives and data sources. The findings reveal various anti-bullying strategies involving different stakeholders; however, gaps are identified within existing approaches. Policymakers emphasized culturally sensitive interventions while acknowledging challenges related to implementation and evaluation processes. Although Abu Dhabi\u27s approach has solid legislative support, incomplete implementation is recognized as a weakness. The analysis of students\u27 survey data showed varied experiences and perceptions regarding bullying among students, leading to a 3 6.7% prevalence rate overall, with higher rates observed in private schools than public ones, especially concerning cyberbullying (37% vs 27%). Additionally, numerous instances where over half have witnessed online bullying were reported. Moreover, it was notable that only about one-fourth inform teachers about these incidents while nearly half report them to parents, the latter being slightly more noticeable among private school attendees, reporting 47% versus public at 42%. It emerged further that less than fifty percent confirm the proper policies for reporting such cases, indicating limitations from private and public schools. Additionally, fear associated with bullies holds significance amongst factors underlying hesitancy surfacing during surveys. This study provides valuable insights on potential areas that focus on enhancing efficient policy enforcement against such issues, thus serving as critical input informing future decision-makers towards effective preventive measures
DESIGN, SYNTHESIS AND CHARACTERIZATION OF ZINC AND GOLD-BASED METAL-ORGANIC FRAMEWORKS AND COMPLEXES FOR THE DETECTION AND TREATMENT OF CANCER
Get PDFThe early detection of cancer plays a pivotal role in improving patient outcomes, emphasizing the urgent need for highly sensitive and selective biosensing platforms. Metal-Organic Frameworks (MOFs) have emerged as promising candidates in this domain due to their tunable properties, large surface area, and high porosity. Herein, the utilization of zinc-based MOF as a sophisticated biosensing platform tailored for the precise detection of the HER2 cancer biomarker is presented. HER2, a critical protein marker in breast cancer diagnostics and treatment, demands highly selective and accurate detection methods for effective patient management. Simple hydrothermal synthesis methodology has been adopted to synthetize zinc-based MOF while the structural properties of this MOF are thoroughly examined to elucidate its inherent advantages in biosensing applications. Based on the tunability of MOF, functionalization strategies and surface engineering were employed to enhance the specificity of zinc-based MOF towards HER2. Additionally, incorporating advanced fluorescent ligand provides a robust fluorescent-based assay for the sensitive detection of HER2. To comprehend the interaction between the protein and zinc-based MOF, a computational docking was operated.Cancer treatment has long been a challenging endeavor, prompting researchers to explore innovative approaches. One promising avenue involves the use of organic-inorganic hybrid structures, which offer unique advantages in targeting cancer cells. Herein, investigating the efficacy of employing such hybrid structures in cancer treatment, particularly focusing on their performance in Fenton reaction and chemodynamic therapy (CDT) was implemented. Utilizing organic-inorganic hybrid nanostructures including MOFs, Coordination Polymers (CPs) and organic/inorganic complex as anticancer agents have shown promise as efficacy in combating cancer. The influence of small size on activity is examined, elucidating how nano-scale dimensions enhance therapeutic outcomes by facilitating cellular uptake and targeted delivery. Furthermore, the selection of biocompatible inorganic elements such as gold and zinc has demonstrated significant efficacy in cancer treatment while ensuring safety towards normal cells. On the other hand, the choice of organic ligands is explored, highlighting its fundamental role in modulating the reactivity and selectivity of hybrid structures in cancer treatment. Through a comprehensive analysis of experimental data, valuable insights into optimizing the design of organicinorganic hybrid structures for enhanced efficacy in cancer therapy have been revealed, thereby contributing to the advancement of precision medicine and personalized treatment approaches
FABRICATION AND EVALUATION OF MULTICOMPONENT BIOMIMETIC SCAFFOLDS FOR BONE TISSUE ENGINEERING
Get PDFBones have an inherent ability to remodel, but critical-size defects can hinder regeneration, leading to delayed healing or non-union fractures. Traditional bone grafts have limitations, such as donor site morbidity and immune rejection, driving the need for synthetic bone substitutes. Bone tissue engineering (BTE) addresses this by developing biomimetic scaffolds that replicate bone properties. This research aimed to fabricate composite scaffolds from strontium (Sr) and zinc (Zn) doped nano-hydroxyapatite (nHAp), collagen, and poly(lactide-co-glycolide) (PLGA) polymer. Different doping percentages of Sr/Zn (1%, 2.5%, 4%) were used to fabricate the scaffolds using supercritical CO2 (ScCO2) and electrospinning techniques. Scaffolds were then analyzed for their spectral properties, structure, porosity, mechanical strength, bioactivity, biodegradation, biocompatibility, and antibacterial efficacy. Results showed that scaffolds fabricated with both techniques exhibited low crystallinity at higher Sr/Zn doping levels, which improved the scaffold\u27s bioactivity. The Sr/Zn-nHAp-PLGA scaffolds fabricated using ScCO2 exhibited favorable biodegradability in simulated body fluid (SBF) and adequate pore size of 189-406 μm. Notably, the 2.5% Sr/Zn-nHAp-PLGA scaffolds demonstrated improved ultimate compressive strength of 15.06 ± 3.05 MPa and Young’s modulus of 0.196 ± 0.007 GPa, while the 4% Sr/Zn-nHAp-PLGA scaffolds exhibited the highest antibacterial activity and promoted osteoblastic proliferation, though they lacked homogeneity and displayed lower ultimate strength. In comparison, electrospun Sr/Zn-nHAp-collagen-PLGA scaffolds were confirmed as composites by spectral analysis. The 4% Sr/Zn scaffolds had a fiber diameter of 331.6 ± 96.11 nm and a pore size of 233.5 ± 18.8 μm, they demonstrated bioactivity by forming needle-like calcium phosphate crystals after immersion in SBF. Additionally, their good homogeneity contributed to excellent mechanical strength, with Young\u27s modulus of 9.91 ± 1.7 GPa, which is comparable to that of cancellous bone. In summary, the electrospun scaffolds demonstrated better stability, bioactivity, and mechanical properties, highlighting the superiority of electrospinning and the promising potential of these scaffolds for BTE
INVESTIGATING THE BIDIRECTIONAL ASSOCIATION BETWEEN SOCIODEMOGRAPHIC PREDICTORS AND SELF-REPORTED DEPRESSION AMONG ADULTS IN THE UNITED ARAB EMIRATES
Get PDFBackground: Globally, the prevalence of depression among adults is increasing, adversely affecting public health, daily functioning, and productivity. Epidemiological studies have established a strong correlation between depression and other risk factors. However, the aspects of this relationship have not been thoroughly explored in the United Arab Emirates (UAE). The aim of this study was to explore the association between self-perceived depression and other risk factors, such as sociodemographic characteristics, sleep duration, body mass index (BMI), and underlying chronic diseases such as diabetes and hypertension after adjustment for age and gender, among Emirati Adults. Methods: This cross-sectional study is part of the UAE Healthy Future Study (UAEHFS), one of the first extensive prospective cohort studies in the region focusing on the causes and risk factors for chronic diseases among UAE nationals. For this research, we analyzed the UAEHFS pilot data. We used the eight-item Patient Health Questionnaire (PHQ-8) as a screening instrument for depression among participants. The prevalence proportion of depression was estimated, and in the complete-case analysis, we applied a multivariate logistic regression model using the binarized PHQ-8 along with other variables. Odds ratios (ORs) with 95% confidence intervals (CI) were computed. A p-value of less than 0.05 was considered statistically significant. All statistical analyses were performed using R software, version 4.2.3. Results: Out of 517 participants who met the inclusion criteria, 487 (94.2 %) completed the questionnaire and were included in the statistical analysis using 100 multiple imputations. After excluding cases with missing values, 231 participants (44.7%) were included in the primary statistical analysis. The median age of participants was 32.0 years (Interquartile Range: 24.0, 39.0). In total, 22 participants (9.5%) reported experiencing depression. When comparing categorical groups within the PHQ-8 depression classification (\u3c 10 versus ≥ 10), a statistically significant difference was observed between the categorical variables. Females have shown significantly higher odds of reporting depression than males, with an odds ratio of 3.2 (95% CI:1.17, 8.88). Unhappy individuals had approximately five times higher odds of reporting depression compared to their happy counterparts. Additionally, for each interquartile-range increase in age and body mass index (BMI), the odds ratios of reporting depression were 0.34 (95% CI: 0.1, 1.0) and 1.8 (95% CI: 0.97, 3.32) respectively. The total PHQ-8 score was statistically significant negatively associated with sleep categories with odds ratios OR of 0.965 (95% CI:0.954, 0.976) and 0.961 (95% CI: 0.948, 0.974) in the univariate and multivariate logistic regression model respectively. The odds ratio for Glycosylated hemoglobin (HbA1c) is 1.033 (95% CI: 0.998, 1.069), indicating a slight increase in the odds of reporting depressive symptoms with higher HbA1c levels. However, the association is not statistically significant as the 95% confidence interval CI includes the value of 1. The odds ratio for blood pressure is 0.99 (95% CI: 0.882, 1.112), indicating no statistically significant association with reporting depressive symptoms as the 95% CI includes the value of 1. Conclusion: Females are more likely to report depression compared to males. Increasing age may reduce the risk of reporting depression. Single individuals exhibit higher levels of depression than their married counterparts. Unhappy individuals have approximately 5-fold higher odds of reporting depression compared to happy individuals. A higher BMI was associated with an increased risk of reporting depression. Additionally, Individuals who reported shorter sleep durations were more likely to report depression than those who reported sleeping 7 hours or more. No significant associations were found between total PHQ-8 scores and blood pressure or HbA1c levels. Significant contributions: The results of this study have significant value for researchers and public health professionals, as they provide novel data on the PHQ-8 score in a healthy UAE population, an area that has not been previously explored. This study enriches our understanding of depression in this context and could inform future public health strategies and research initiatives. It has implications for policymaking, addressing gaps in the health insurance system, and promoting public health efforts, particularly regarding the integration of mental health and public health in the UAE and the Gulf region
TITRISATION ET «SUKUKISATION» EN DROIT TUNISIEN
Get PDFBanks and financial institutions sometimes have to invest the debts they owe to others because they need money by transferring them to others through many means, the most important of which is securitization, which is the transfer of debts to a mutual debt fund in exchange for tradable securities in the market. However, securitization in this commercial form led to the transfer of debt-related risks to the financial market, which actually caused the global financial crisis of 2008.
Therefore, sukuk represents the Islamic alternative to securitization in terms of its subjection to Islamic controls, the most important of which is the inadmissibility of selling debts, so that the funds transferred to the mutual fund for sukuk are limited to ownership or usufruct rights. Any money actually earned or to be earned. The topic of the research mainly relates to the comparison of the two processes.
On the one hand, both securitization and sukuk are similar in the mechanisms and nature of the institutions involved in the bond offering process, and they raise an important legal problem in terms of the absence of the legal personality of the two funds with their offering of bonds.
On the other hand, the two processes differ in their essence. If sukuk seems to be consistent as it transfers real rights to rights on bonds, securitization raises the problem of distinguishing between the personal right - the debts that were transferred to the mutual fund - and the property right that the investor acquires on the bonds.
تضطر البنوك والمؤسسات المالية أحيانا الى استثمار الديون التي لها على الغير لحاجتها للمال و ذلك بتحويلها للغير عبر عديد الوسائل و أهمها التوريق أو التسنيد الذي يتمثل في إحالة ديون لصندوق مشترك للديون مقابل الحصول على أوراق مالية قابلة للتداول في السوق. غير أن التوريق في صيغته التجارية هذه أدى الى نقل المخاطر المتعلقة بالديون الى السوق المالية وهو ما سبّب فعليا الأزمة المالية العالمية لسنة2008.
لهذا يمثل التصكيك البديل الإسلامي للتوريق من حيث خضوعه للضوابط الإسلامية وأهمها عدم جواز بيع الديون، بحيث يقتصر الأموال المُحالة على الصندوق المشترك للصكوك على حقوق ملكية أو انتفاع. أي أموال مكتسبة فعلا أو سيتم اكتسابها. يتعلق موضوع البحث أساسا بمقارنة العمليتين.
من جهة أولى يشترك كل من التوريق و التصكيك في الآليات و طبيعة المؤسسات المتدخلة في عملية طرح السندات و يطرحان إشكالية قانونية هامة من حيث انتفاء الشخصية المعنوية للصندوقين مع طرحه للسندات.
غير أنه من جهة ثانية تختلف العمليتان من حيث جوهرهما، فلئن بدا التصكيك منسجما إذ يحوّل حقوقا عينية لحقوق على سندات فان التوريق يثير إشكال التمييز بين الحق الشخصي- الديون التي تمت إحالتها للصندوق المشترك-وحق الملكية الذي يكتسبه المستثمر على السندات
The Level of Awareness of Primary School Teachers about Fluency Skill and Teaching Strategies
Get PDFThe current study aimed to reveal the level of primary school teachers\u27 awareness of the skill of reading fluently and the strategies for teaching it, and to reveal the impact of the study variables (teacher\u27s gender, specialization, degree, number of years of experience), and accordingly. A questionnaire consisting of twenty-three statements was designed to measure the level of awareness of stage teachers. Elementary reading skills and teaching strategies: (awareness of reading fluently and its elements, strategies for teaching reading fluently). The researchers applied the tool to 340 primary teachers. The results of the study showed that the level of primary school teachers\u27 awareness of the skill of reading fluently, and its teaching strategies reached a moderate degree in all domains. Based on the results of the study, the recommendations appear as follows: The need to implement training courses targeting primary school teachers in raising awareness of the skill of reading fluently and strategies for teaching it, in addition to holding support workshops and spreading awareness in primary schools. society through various media and emphasizing the importance of raising awareness of the skill of reading fluently and the strategies by which it is taught.
Keywords: primary school teachers, reading fluency, teaching strategies, fluency skil
The Relative Contribution of Emotional Support Sources in Predicting the Academic Motivation among Female University Students
Get PDFThe purpose of the current study is to reveal the relative contribution of Emotional support sources in predicting the academic motivation (both intrinsic and extrinsic) among female students at Princess Alia University College in Jordan. Furthermore. In addition, it aims to identify the differences, if any, in the academic motivation considering academic achievement. To accomplish these objectives, the researchers utilized the Academic Motivation Scale developed by Lepper, et al. (2005) and the Emotional Support Sources Scale developed by Uchida, et al. (2008) after confirming their psychometric properties. A stratified random sample was used in this study, which included 296 female students from Princess Alia University College, for the academic year 2021/2022. The results showed that there are differences in intrinsic motivation of students in favor of higher academic achievement, and there are also differences in extrinsic motivation in favor of lower academic achievement. The multiple regression analysis demonstrated that emotional support from teachers and parents accounted for 0.269 of the variance in intrinsic academic motivation. Moreover, emotional support from social media, teachers, and parents explained 27.3 of the variance in extrinsic academic motivation.
Keywords: Emotional Support Sources, Academic Motivation (Intrinsic, Extrinsic), Princess Alia University College, Jorda
THEORETICAL AND COMPUTATIONAL ASTROCHEMISTRY: A VARIATIONAL QUANTUM MONTE CARLO (VQMC) STUDY OF THE TRIHYDROGEN MOLECULE CATION (H3+)
Get PDFH3+ is the simplest Three-Center Two-Electron molecule and it is of much interest in astrochemistry due to its high occurrence in the outer space, high reactivity, and strong acidic properties. In addition,H3+ is involved in many chemical reactions in the interstellar medium (ISM) and its significant ability to absorb energy contributed to the cooling of the Universe during its early stages.
The main objective of this thesis is to approximate the ground state electronic energy of H3+ by using a simple trial wavefunction consisting of a doubly occupied molecular orbital multiplied by a Jastrow factor. The latter factor allows us to introduce some degree of electron correlation. With this trial wavefunction, we derived an expression for the local energy which was then implemented in a Variational Quantum Monte Carlo (VQMC) code in line with a Metropolis algorithm sampling technique. Moreover, the computer code was written in Python 3.6 language and was first tested on an analytically solvable system which is the quantum harmonic oscillator (QHO). Finally, the equilibrium H-H bond length at the fixed equilateral geometry and the normal breathing frequency were estimated.
The calculated equilibrium H-H bond length of the equilateral triangular geometry is 1.800 Bohr (0.95 Å) which is only 1.8% as a deviation from the experimental value of 1.833 Bohr (0.97 Å). Furthermore, the symmetric normal breathing frequency was also calculated to be 3240 cm-1 with a small error percentage of 1.9% from the obtained experimental value of 3178 cm-1. Thus, both values of bond length and frequency are in good agreement with the experiment and prior theoretical studies on the molecule. Last but not least, the calculated ground state energy value was -1.256458 Hartree. As a conclusion, the theory developed in this thesis goes beyond the independent-particle approximation and leads to promising, reliable, and reproducible results despite the simplicity of the used trial wave function