United Arab Emirates University
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A COMPUTATIONAL INVESTIGATION INTO THERMO-KINETIC PARAMETERS GOVERNING THE DECOMPOSITION OF BIO-OIL MODEL COMPOUNDS
Get PDFAmong notable products from thermal degradation of biomass are simple oxygen-containing aromatics. These compounds typically appear in high loads in collected bio-oil derived from biomass. As such, it is important to comprehend the decomposition chemistry of this category of compounds. This thesis takes on board a general approach to report thermo-kinetic parameters that govern decomposition of a selected set of bio-oil model compounds in two distinct systems: firstly radical-derived pathways in the gas phase and secondly thermal degradation in their condensed media. The first is attained through accurate density functional calculations while the second is accomplished through the use of Model-free and model-fitting approaches to analyse mass loss curves attained in thermogravimetric analysis (TGA). In the first part of thesis, we explored reactions of the hydroperoxyl (HO2) radicals’ anisole, cresol, guaiacol, and vanillin with the underlying aim to assess the accuracy of existing kinetic models in the literature in predicting their ignition delay time; an important combustion character of a fuel. Using updated kinetic parameters for initial H abstraction reactions by HO2 from these biooil model compounds has only slightly altered ignition delay times while considering various operating pressures. Along the same line of enquiry, we found that radical-derived decomposition of cresol and guaiacol to take place predominantly through abstraction of the hydroxyl’H with a noticeable contribution for abstraction from the methyl site. In case of vanillin, abstraction from the aldehyde’s and hydroxyl’H assume comparable importance. We calculated bond dissociation enthalpies in these compounds as to locate the preferable abstractable sites. Arrhenius parameters were provided for a large set of reactions. Such findings are expected to enhance the accuracy and predictability of kinetics models that account for oxidative and pyrolytic decomposition of biomass surrogate compounds. In attaining the second objective of the thesis and based on the obtained TGA and DTG profiles, model-free methods, specifically the KAS model, FWO model, and Starink model were used to derive thermo-kinetic parameters for oxidative and pyrolytic decomposition of for catechol and maltol. Decomposition mechanisms were then determined using the Coats and Redfern method for fitting kinetics. It is hoped that outcomes of this work to advance our comprehensions of the complex chemical reactions that prevail during decay of bio-oil model compounds
ASSESSING THE IMPACT OF IRRIGATION WATER AND SOIL SALINITY ON DATE PALM AND DESERT SOIL ASSOCIATED MICROBIOTA
Get PDFSoil salinization poses a critical challenge in arid and semi-arid regions, where water scarcity is exacerbated by climate change and unsustainable agricultural practices. This phenomenon not only reduces soil fertility but also significantly impacts groundwater quality, leading to detrimental effects on crop yields and ecosystem health. Date palm (Phoenix dactylifera) cultivation, a key agricultural practice in many arid regions, often relies on saline groundwater for irrigation due to limited freshwater resources and low precipitation rates. The use of saline water can create an intricate balance between providing necessary nutrients and introducing harmful salts into the soil. While the role of plant-associated microbiota is vital for nutrient cycling, plant health, and overall ecosystem functioning, the impact of increasing salinity on these microbial communities remains underexplored. Understanding how different irrigation practices and soil salinity influence microbial diversity and community structure is essential for developing sustainable agricultural strategies in arid environments. This study aims to fill this knowledge gap by investigating the effects of freshwater and saline groundwater irrigation on the fungi associated with date palms using high-throughput sequencing of the Internal Transcribed Spacer 2 (ITS2) gene region. Additionally, we examine bacterial diversity in the salt flats of Abu Dhabi, UAE, focusing on seasonal variations through culturomics-based methods, as well as the salt tolerance and enzymatic capabilities of these bacteria. The findings indicate that root-associated fungal communities differ significantly between irrigation water sources, with water pH and electrical conductivity (EC) as major influencing factors. Under saline groundwater irrigation, we observed a higher abundance of saprotrophic operational taxonomic units (OTUs) such as Acrocalymma vagum, Coprinopsis sp., and Myrothecium sp. Conversely, saline groundwater irrigation reduced the number of unique fungal OTUs in the soil while increasing the abundance of pathotrophs. In the bulk soil, fungal richness negatively correlated with soil pH, with both dispersal limitation and demographic stochastic processes shaping community structure. Interestingly, saline groundwater irrigation did not affect fungal richness or diversity in leaves; however, comparatively a higher percentage of unique OTUs was identified in leaves irrigated with saline water, with richness negatively correlated to soil EC, pH, and soil OM. The diversity index showed a positive correlation with irrigation groundwater pH in leaves. The members of the order Dothideales and Aureobasidium sp. were more abundant under saline groundwater irrigation in leaves. Also, stochastic drift was identified as the major ecological process in leaf fungal assembly. In the salt-flat study, the Bacillota phylum dominated across all seasons, with prevalent species including Bacillus paralicheniformis, B. licheniformis, B. vallismortis, and B. tropicus. Seasonal variations were evident, with greater bacterial richness noted at the end of the growing season. Most isolates showed tolerance to 10% NaCl and exhibited significant enzymatic activities, including cellulases (90%), proteases (85%), hydrolases (100%), and transferases (100%). The findings show that irrigation with saline groundwater profoundly influences fungal diversity and community composition, with pH and EC emerging as critical environmental factors. Increased abundance of saprotrophic fungi under saline conditions suggests their potential role in enhancing nutrient cycling and promoting plant growth, even in challenging environments. Conversely, the reduction of unique OTUs in soil and the prevalence of pathotrophs highlight the potential risks associated with saline irrigation, which may threaten soil health and plant vitality. Moreover, the salt flats study displays the resilience of microbes in extreme conditions, revealing high salt tolerance and significant enzymatic activity among the dominant species which opens avenues for biotechnological applications, particularly in agriculture and industrial enzyme production. The implications extend beyond local agricultural systems, informing global strategies for managing soil health and ensuring food security in an era of climate variability. Future studies should explore the long-term effects of saline groundwater irrigation on microbial communities and their functional capacities, further elucidating the potential for harnessing microbial resilience in sustainable agricultural practices
The Effectiveness of an Educational Program in Developing Mathematical Achievement as well as Developing Productive Struggle among Students of Intermediate Stage
Get PDFThis study aimed to identify the effectiveness of an educational program in developing Mathematical Achievement and productive struggle among students of intermediate stage. To fulfil its goals the study used the quasi-experimental approach, based on the design of two equivalent groups. It also used the Teacher\u27s Guide - an activity booklet as study material, in addition to the use of two tools to collect data. One of them is an achievement test that included (three levels of mathematical knowledge related to equation and inequalities) and the other is a productive struggle scale (divided into three axes). The study sample consisted of (33) of the second-grade intermediate students at Al-Darb Province in the Kingdom of Saudi Arabia. The number of members of the experimental group reached (17) students, while the number of members of the control group reached (16) students. The study reached several results the most notable of which is that there is a statistically significant difference at the level of significance of 0.05 ≥ α between the mean scores of students in the experimental and control groups in the achievement test and the measure of productive struggle in favor of the experimental group. In addition, it revealed that there is a significant correlation between mathematical achievement and productive struggle. In light of its results the study recommended several recommendations the most important of which include developing teachers’ Guides, adding parts to refer to the previous and later mathematical knowledge related to the lesson, in addition to including the guide with teaching practices that support the productive struggle in teaching and learning mathematics.
Keywords: Educational Program - Intermediate Stage -Mathematical Achievement - Productive Struggl
ASSESSMENT OF HEAVY METAL CONCENTRATION IN ORANGE-SPOTTED TREVALLY (FLAVOCARANX BAJAD) FROM TWO COASTAL LOCATIONS IN ABU DHABI, UNITED ARAB EMIRATES
No full textThis study investigates concentration of heavy metals in the Orange-spotted Trevally (Flavocaranx bajad) from two distinct coastal areas in Abu Dhabi Emirate, Sila and Abu Dhabi. Heavy metals pollution poses a significant risk to both marine ecosystems and human health; thus it is vital to conduct comprehensive assessments of heavy metal contaminations in aquatic life. The main aim of this study is to quantify the levels of heavy metals and assess their concentrations in gill, muscle, and liver tissues of the Orange-spotted Trevally from both sites. The samples were prepared and analyzed using microwave digestion system and ICP Optical Emission Spectrometer to determine metal concentrations. The Metal Pollution Index (MPI) and Fulton’s Condition Factor (K) were calculated, and the Principal Component Analysis was used to further interpret the results and visualize it. The results revealed that the locations differ from one another, in terms of heavy metal concentrations in samples, and both locations had Metal Pollution Index (MPI) indicating no toxicity, despite slight exceedences of some maximum permissible limits. This study contributes to the understanding of the extent of metal pollution in Abu Dhabi’s marine environment and aquatic life. Moreover, it emphasizes the importance of continuous monitoring and the need to develop effective regulatory frameworks that will contribute to safeguarding the marine environment and its resources, ensure public health, and eliminate direct discharge containing metal pollution
DEVELOPMENT OF HIGHLY EFFICIENT HYBRIDFUNCTIONALIZED MEMBRANES FOR SUSTAINABLE WATER HARVESTING
No full textWater scarcity has emerged as a critical global challenge. This problem catches the world\u27s interest through events such as the severe drought in Europe during the summer of 2022. While desalination plants offer a solution, their high energy consumption necessitates the exploration of alternative, sustainable water resources. Addressing the urgent need for alternative water resources in the face of increasing water scarcity. A viable option was presented by fog harvesting, which is a method to collect water from atmospheric fog. This method was initially developed to meet the demands of a variety of sectors such as agricultural purposes, and household use, and reduce the load on the desalination plants by using the advancements in material science that have expanded its potential to meet broader water demands. This research explores enhancement in fog collection efficiency using nanocomposite materials, specifically polyvinylchloride/titanium oxide (PVC/TiO2) and polystyrene/titanium oxide (PS/Ti O2). Additionally, the study examines the potential of polyethylene 2,5-furanoate (PEF), a biobased polymer derived from plant sources, as a sustainable alternative to polyethylene terephthalate (PET) for water harvesting applications. An aluminum mesh was employed as the base structure for the fog collectors. After that, it was coated with our polymer composite constructed through dipping and electrospinning methods. The coated polymer composite mesh demonstrated significant improvements in water harvesting rates. The findings suggest that innovative material combinations can lead to alternative, sustainable, and renewable sources of water
PERFORMANCE OF PERVIOUS GEOPOLYMER CONCRETE MADE WITH LOCALLY AVAILABLE RECYCLED CONCRETE AGGREGATES IN AN ARID ENVIRONMENT
No full textThis dissertation aims to develop sustainable pavement materials to address environmental challenges in arid environments, specifically in the United Arab Emirates (UAE). These challenges include the depletion of natural resources, excessive cement production, industrial waste accumulation, and stormwater runoff flooding. Cement-free pervious concrete made with geopolymer and recycled concrete aggregates (RCA) are presented as sustainable solutions to these issues. The porous nature of pervious concrete reduces stormwater runoff while using RCA and geopolymer reduces dependence on limited natural resources and mitigates the environmental impact of cement production by incorporating industrial waste materials. In this thesis, the use of pervious geopolymer concrete in pavement applications was assessed in three phases. In the first phase, the effect of various mix design parameters on the mechanical, hydraulic, and durability properties of pervious geopolymer concrete (PGC) was evaluated. The mixes were formulated using the Taguchi method and tested for compressive strength, permeability, and abrasion resistance. Based on preset criteria and weighting, the optimum mix was developed using the Taguchi-TOPSIS method and further verified experimentally. The optimum mix for scenarios with compressive strength and abrasion resistance having the highest weights was composed of binder content of 500 kg/ m3, dune sand addition of 20%, AAS/B of 0.60, and SH molarity of 12 M. Meanwhile, the optimum mix for the permeability-dominant scenario included 400 kg/m3 of binder content, 0% of dune 21 sand addition, 0.60 of AAS/B, and 12 M of SH molarity.In the second phase of this study, the sustainability of PGC mixes was further enhanced by replacing natural aggregates with recycled counterparts from construction and demolition waste. The resulting pervious geopolymer recycled aggregate concrete (PGRAC) was produced at design porosities of 10% and 15% and two binder combinations (GGBS ratios of 1:0 and 1:1). RCA replaced natural coarse aggregate (NCA) at up to 100% replacement. The effect of these mix design parameters on the physical, mechanical, hydraulic, and durability properties was evaluated. The results showed that the incorporation of RCA or fly ash into the PGC mix reduced the hardened density, strengths, and abrasion resistance while increasing porosity and permeability. Despite permeability losses reaching 71% due to clogging, nearly 94% of the initial permeability could be restored through pressurized water washing. In the third and final phase, the leaching potential and pollutant removal efficiency of PGRAC were studied, considering variations in design porosity, binder blend, and RCA replacement. While the binder blend and alkaline solution significantly influenced the leaching behavior of heavy metals, design porosity, and RCA replacement had a minimal direct impact. With time, the leaching of heavy metals diminished, indicating a reduced environmental and structural risk. RCA replacement and increased porosity were effective in pollutant removal, with binder blend effects dependent on both design porosity and RCA replacement, influencing both short- and long-term performance. Overall, the research provides evidence on the ability to utilize PGRAC in pavement applications in arid environments, offering both environmental and structural benefits
FABRICATION AND EVALUATION OF MULTICOMPONENT BIOMIMETIC SCAFFOLDS FOR BONE TISSUE ENGINEERING
No full textBones 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). 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 (P = 0.00024, n = 3). Notably, the 2.5% Sr/Zn-nHAp-PLGA scaffolds demonstrated improved ultimate compressive strength of 15.06 ± 3.05 MPa (P = 0.041, n = 3) 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. 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
THE EFFECT OF NEROLIDOL ON THE RENAL DYSFUNCTION FOLLOWING BILATERAL URETERAL OBSTRUCTION IN THE RAT
Get PDFThis thesis addressed nerolidol’s potential therapeutic and protective effects on bilateral ureteral obstruction-induced uropathy in rats. Obstructive uropathy stands as a notable contributor to acute kidney injury (AKI), accounting for 5-10% of all AKI cases worldwide, with a particularly high prevalence among the elderly, constituting 22% of AKI cases in this age group. Urinary tract obstruction, often attributed to factors such as kidney stones, urinary tract deformities and benign/malignant growths such as benign prostatic hyperplasia (BPH) in older men can lead to detrimental outcomes if left untreated, potentially progressing to kidney failure and even mortality. The severity of the kidney injury is contingent upon the nature and duration of the obstruction. Common treatment approaches include surgical intervention to remove the obstruction and the subsequent monitoring of the serum chemistry of the patient to address any post-obstruction complications that could lead to alterations in kidney function and prescribing the appropriate medications. Recently, there has been a burgeoning interest in exploring natural products that are seen as a potential alternative remedy for many diseases and conditions. This is due to their low toxicity, affordability, and wide availability, which underscores the need for comprehensive research to address the therapeutic potential of these natural products. Nerolidol, which is a naturally occurring sesquiterpene alcohol compound found in the essential oils of many plants, is believed to exhibit a wide range of pharmacological and biological activities, making it a hot topic of clinical research. Although nerolidol has exhibited effectiveness in various organ-related conditions, as reported by several research studies, its effects on renal dysfunction following reversible bilateral ureteral obstruction (BUO) remain unexplored. Hence, the primary objective of this research was to investigate the in-vivo effects of nerolidol on the alterations in renal function associated with BUO in the rat. Nerolidol was administered orally to Wistar rats using an oral gavage needle after being dissolved in corn oil which was used as a vehicle. Nerolidol was administered as a single daily dose of 200 mg/Kg for 14 consecutive days. Sham group (n=12) underwent sham surgery, whereas the BUO group (n=12) and BUO/NERO group (n=12) underwent reversible 24-hour BUO and received the vehicle or Nerolidol, respectively. The treatment started 9 days prior to the BUO/Sham surgery and continued till 4 days post-BUO. Renal functional parameters and histological changes were assessed before the start of the treatment (Basal), just prior to the intervention (BUO/Sham surgery) (Pre-BUO) and 4 days after the intervention (Post-BUO). The gene and protein expression levels of some important markers of renal injury, inflammation, fibrosis, apoptosis, autophagy, and oxidative stress were measured using PCR and western blot techniques. Neither nerolidol nor the vehicle affected the basal renal functions. The administration of nerolidol resulted in a significant attenuation in the BUO-induced alterations in renal functional parameters such as serum creatinine and serum urea, creatinine clearance and urinary albumin-creatinine ratio. Nerolidol also exhibited the ability to attenuate the changes in several markers associated with renal injury, inflammation, fibrosis, autophagy, and oxidative stress. Moreover, nerolidol was able to attenuate the BUO-induced alterations in kidney histology. The study\u27s findings may provide insights into the potential therapeutic and reno-protective effects of nerolidol on obstructive uropathy-induced kidney injury that could be extended to the clinical setting
PRACTICES AND PERCEPTIONS OF UAE RESIDENTS: FOOD SAFETY IN HANDLING AND PREPARATION OF FISH, CONSUMPTION, AND NUTRITION FROM FISH
Get PDFBackground: UAE is uniquely located with an extensive seafront, which has led to the development of fishing and fisheries in the country. As a result, the UAE\u27s diverse population has become one of the highest fish consumers among the Gulf countries. The high fish consumption in the UAE was a part of the traditional diet; however, a better understanding of UAE residents\u27 practices and perceptions of fish food safety, fish preparation, and nutrition from fish consumption was needed. Objective: This study investigates food safety practices in handling and preparation of fish, consumption trends, and perceptions of nutrition from fish among UAE residents. Method: A cross-sectional survey using convenience sampling was conducted on 390 participants aged 18+ and residing across the seven emirates in the UAE. The survey questionnaire had four sections: food safety of fish handling, fish preparation and consumption, nutrition from fish consumption, and demographic characteristics. Results: The study respondents included a Female:Male ratio of 60:40, 48% (25–44 years) and 33% (18–24 years) old. During fish purchases from the market, 41% of participants considered whether the fish looks clean and fresh, and 38% considered whether fish sellers wear masks and gloves. Most participants (67%) purchased fresh/refrigerated fish, followed by frozen fish (19%), and the majority (77%) refrigerated the fish within 2 hours of purchase. During fish preparation, 80% of respondents washed their hands, and 52% used a different board and knife after coming in touch with raw fish. Participants were preparing baked, roasted or broiled fish (61%), pan-fried fish (44%), deep-fried fish (32%), and smoked fish (22%) once a week or more. The other preparation methods, such as boiling or poaching, raw in sushi, microwaving or steaming, raw in sashimi, and sous vide, were less frequently used. Participants consumed Salmon fish (52%), Orange-spotted Grouper (Hamour) (50%), Kingfish or Spanish mackerel (Kanaad) (46%), Tuna fish (45%), Sea Bream fish (39%), and Spangled Emperor (Sheri) (32%) species once a week or more. The other fish species, such as Mullet Fish (Biah), Orange-spotted Trevally (Jash), Rabbitfishes or Spinefoots (Safi), Sardines (Ooma), Red Snapper (Hamra), Painted Sweetlips (Farsh), Greater Amberjack (Halwayo, or Hamam), and Tilapia fish (Bolti), were less frequently consumed. Participants identified fish as an essential component in a balanced diet (97%), identified fish as a good source of omega-3 fatty acids (PUFA) (91%), protein (90%), iron (70%), vitamin D (66%), calcium (57%), B vitamins (53%), vitamin A (49%) and saturated fat (38%). Conclusion: UAE residents have a good understanding of food safety practices during fish purchase, handling, and preparation. They prefer baking the fish over other cooking techniques, consuming salmon over other fish species, and identifying fish as a healthy and nutritious food. This research study contributes to understanding the consumers\u27 practices and perceptions regarding the safety of fish consumption
INDUCTION PROGRAM PRACTICES ON NEW TEACHERS IN PUBLIC SCHOOL IN THE UNITED ARAB EMIRATES
Get PDFThis study examines the induction program practices for new teachers in United Arab Emirates (UAE) public schools. It evaluates key components—including orientation, mentoring, professional development, teacher networking, and administrative support— and analyzes their impact on new teachers’ integration, professional growth, and overall satisfaction. Additionally, it investigates how demographic factors such as nationality, educational qualifications, and teaching experience influence teachers’ experiences and perceptions. By employing a cross-sectional survey design, quantitative data were collected from 150 public school teachers across various emirates. Findings revealed that most new teachers held positive perceptions of the induction program domains. Gender comparisons indicated minimal differences, except in administrative support, where male teachers reported significantly higher satisfaction than female teachers, with a small-tomoderate effect size. Nationality, educational qualifications, and program duration did not significantly impact perceptions across the domains. However, teaching experience significantly influenced perceptions in four domains—mentoring, professional development, teacher networking, and administrative support—with teachers having 0–1 years of experience rating these domains more favorably than their more experienced counterparts. These results indicate that less experienced teachers derive greater benefits from induction programs and underscore the necessity for sustained support. The study recommends enhancing induction practices through long-term support, tailored professional development, and strengthened administrative guidance, which are pivotal for advancing new teachers’ professional growth and contributing to the UAE’s broader educational objectives