AUB ScholarWorks (American Univ. of Beirut)
Not a member yet
33634 research outputs found
Sort by
Are Green Spaces an Effective Way to Remove Air Pollution in Urban Area of Beirut, Lebanon
No full textAir pollution stands as a environmental concern, representing a significant contributor to global mortality rates. Despite efforts to improve air quality, existing interventions often fall short of addressing the magnitude of this issue. However, emerging evidence suggests that green spaces and vegetation play a crucial role in mitigating airborne pollutants, particularly particulate matter (PM), through processes such as deposition and absorption.
This study delves deeply into the intricate relationship between green spaces and PM pollution within urban environments. PM samples were collected from designated green sites within the American University of Beirut, as well as contrasting non-green sites along the university's periphery. Employing inductively coupled plasma mass spectrometry (ICP-MS), the collected PM samples underwent thorough analysis to elucidate the predominant metal elements present across various size fractions and site types.
Furthermore, individual particles underwent meticulous scrutiny using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) to unveil their morphology and elemental composition. Additionally, filters were analyzed to determine the concentrations of black carbon.
This comprehensive study enables the identification and characterization of dominant metal elements within PM across different sizes and site types. Moreover, it facilitates the establishment of correlations between the morphology and elemental composition of individual particles and their size and origin (green vs. non-green sites). By shedding light on these intricate dynamics, this research contributes valuable insights into the potential of green spaces to mitigate PM pollution and underscores the importance of incorporating natural solutions into urban planning and air quality management strategies
Detection of Heavy Metal Contamination in Agricultural Soils in Lebanon: Comparative Assessment Between Atomic Absorption and Hyperspectral Imaging
No full textThe levels of heavy metals (HMs) in agricultural lands in Lebanon have been witnessing a noticeable increase in the past few years, due to increased anthropogenic pollution sources. HMs pose a serious threat to the environment for being non-biodegradable and persistent, accumulating thus to dangerous levels in the soil. A constant monitoring of the occurrence and levels of these contaminants in agriculture soils is thus essential. In Lebanon, a continuous environmental monitoring, including the assessment of levels of HMs in agricultural soils on a national level, is lacking. This is due in part to the high cost of analysis. Indeed, the traditional laboratory and chemical analysis methods used for the detection and quantification of HMs are costly and time consuming. Recently, hyperspectral imaging (HSI) emerged as an automated, objective, sensitive and rapid approach in the assessment of the soil contamination status due to its ability to capture and analyze a broad range of spectral information. Accordingly, the proposed research aims at assessing HMs contamination in major agricultural areas in Lebanon, and evaluate the effectiveness of using HSI in the detection of HMs in contaminated agricultural fields. Additionally, the study aimed at assessing the use of HSI and machine learning for the classification of soil based on its percent particle size distribution.
Soil samples were collected from thirty-nine different locations across the country and were analyzed for Copper (Cu), Nickel (Ni), Lead (Pb), Cadmium (Cd), Chromium (Cr) and Zinc (Zn) using Atomic Absorption Spectrophotometry (AAS). Sources of HMs contamination were assessed and the extent of soil contamination and potential ecological risk were determined using the geo accumulation index and the ecological risk factor. The collected soil samples were also scanned using the Hyspex SWIR-384 to study the soil spectral behavior, and developed machine learning (ML) algorithms (partial least square regression; PLSR, and Support Vector Regression; SVR) were applied to detect and quantify the HMs present in the soil. In addition, the performance of four ML algorithms (support vector machine SVM, random forest RF, linear discriminant analysis LDA and neural network NN) in accurately defining different soil types based on their distinct spectral characteristics and features was evaluated.
The findings from the study revealed alarming soil contamination with Ni and Cd in different agricultural areas in Lebanon. The HM concentrations exceeded to EU permissible limits in soils in 30% and 18% of the tested samples for Ni and Cd respectively. Zinc and copper were both below the EU permissible limits. However, Zn exceeded the WHO target limits in all tested samples, while Cu exceeded the target WHO limits in some locations. HM values above WHO target limits indicate soil pollution without the need for immediate intervention. No soil pollution was detected in the case of Pb and Cr which were below both the EU permissible limits and WHO target values. The calculated I geo index (I geo) revealed moderate to heavy Ni contamination (I geo values between 2 and 4), and heavy Cd contamination (I geo>4 for most of the samples) of the tested soils. Moreover, the contamination factor index (CF) was the highest for Cd showing considerable to very high contamination (CF exceeding 6 in several locations). The ecological risk factor showed very high to extreme contamination for most of the Northern locations, specifically for the case of Ni and Zn.
HSI scans showed that the soil type influences the soil reflectance, where the clayey content and organic matter showed to significantly decrease light reflectance. Mostly, water absorption bands (expressed at 1400 nm and 1900 nm) and adsorption of HMs on iron oxides and organic matter (bands ranging between 2200-2300 nm) were observed. Furthermore, HSI was not successful in the quantification of HMs in agricultural soils. Both PLSR and SVR models exhibited low accuracy (R2 < 0.35) in predicting HM concentrations in the tested soil samples, namely due to the relatively low concentrations measured in these soils. However, HSI and ML were successfully used in soil classification, with the Neural Network model showing the best accuracy in predicting the soil type (R2=0.805).
In conclusion, the study sheds light on the contamination levels of HMs in the Lebanese agricultural soils and the need to address sources of contamination. In addition, the study highlights the potential of using HSI in soil classification while demonstrating the limitation of this technique in determining HM content in soils at relatively low contamination levels
Magnetization Dynamics of CoFe Thin Films Grown by Pulsed Laser Deposition
Get PDFMagnetic damping plays a pivotal role in devices harnessing the electronic spin degree of freedom, significantly influencing their energy efficiency and operational speed. Despite its crucial role, the persistently high Gilbert damping in common ferromagnetic materials, typically on the order of 10−3, presents a challenge for applications in spintronics and spin-orbitronics that require materials with ultra-low damping characteristics. Alternative materials, such as Heusler alloys and magnetic insulators, have showcased significantly lower damping coefficients below 10−4, primarily due to the absence of conduction electrons. Unfortunately, despite their low damping attributes, these materials pose growth challenges and are incompatible with the widely used Complementary Metal-Oxide-Semiconductor (CMOS) technology, limiting their practical utility. Recent developments in material science search for low-damping material, introduce promising prospects. Cobalt and iron binary alloys, particularly Co20Fe80, challenge the conventional limitations by exhibiting relatively low damping coefficients. Theoretical predictions by Mankovsky et al. propose a damping coefficient of 5 × 10−4 in Co20Fe80, highlighting a unique band structure with a sharp minimum in the density of states at the Fermi level. This minimum aligns with the alloy concentration where the least magnetic damping occurs. Subsequent experimental studies by Schoen et al. validate these theoretical predictions, underscoring the potential of Co20Fe80 alloys as materials with minimal damping characteristics. The focus of this thesis is to study the magnetization dynamics of Co60Fe40 thin films prepared through Pulsed Laser Deposition (PLD). The overarching goal is to develop high-quality nanometer-thick films. The investigation kicks off by scrutinizing the characteristics of CoFe films under diverse deposition parameters, manipulating laser energy and temperature to discern optimal conditions. Once these optimal parameters are identified, a systematic exploration of thickness dependence follows, encompassing variations in the CoFe layer thickness within the range of 10 to 25 nm. Moreover, the study extends to exploring the spin-pumping effect in bilayers of CoFe/Pt. In this aspect, the thickness of the Pt layer is systematically varied, enabling the calculation of the spin diffusion length in Pt. This meticulous and systematic study aims to yield valuable insights applicable to the realms of magnonics, spintronics, and spin Hall devices
Less Fairness, More Prosocial Intention and Behavior? Procedural Fairness, Cohesion, and Prosocial and Trust Outcomes: An Assessment of Mediation and Interaction
No full textA group reward account has identified procedural fairness as related to increases in better attitudes towards authority and prosocial behavior, through group cohesion (Blader & Tyler, 2009; Tyler & Blader, 2003). Conversely, a group repair account has experimentally demonstrated that procedural unfairness spurs group-serving prosocial behavior (Barry & Tyler, 2009, 2010). To adjudicate between these two accounts, the present research examined how low, compared to high, procedural fairness is related to trust in national authorities and prosocial intention and behavior, via cohesion. A unique survey of 3,416 residents in Lebanon fielded immediately after the 2020 Beirut blast was used. Predictions for prosocial outcomes were based on the group repair account, and predictions for trust outcomes were based on the group reward account. Specifically, I predicted that perceiving low procedural fairness from authority and, in relation, low group cohesion, would correspond with low trust in authority but, ironically, prosocial intention and behavior towards others affected by the blast. I argue that this may have been the case based on shortcomings of authority presumably perceived in the context of the blast. Additionally, I considered the argument that people especially sensitive to procedural unfairness would disengage from the national group but still assert the worth of the self (Sleebos et al., 2006). Accordingly, I predicted that the magnitude of the indirect relationship between procedural fairness and prosocial outcomes would be larger, and the magnitude of the indirect relationship between procedural fairness and trust in authority would be lower, for participants low (vs. high) on procedural fairness.
In the present work, I demonstrate that perceiving more procedural unfairness of authority was related to prosocial intention and prosocial behavior through seeing that the country was not united—and this was not the case when procedural fairness of authority was perceived. The indirect relationship between procedural fairness and trust, via cohesion, in an allegedly independent government agency, the Council for Development and Reconstruction, was demonstrated, though it did not differ by levels of procedural fairness. There was a direct relationship between procedural fairness and trust in political parties, but not an indirect one through cohesion. Results are discussed in the context of the sectarian political system in Lebanon, and in terms of contributions to the group repair and group reward accounts of procedural (un)fairness. Limitations and future directions are addressed
Redox State in Moringa Oleifera Treated SH-SY5Y Neuroblastoma Cell Line
No full textMoringa Oleifera (MO), the “Miracle Tree”, is a dietary staple that originates from India. All edible components of the tree (pods, flowers, seeds, bark, leaves) have been extensively studied and showed a richness in an array of essential amino acids, vitamins, minerals, and antioxidants. Evidence-based studies highlight the significance of the administrative treatment of MO extracts as a preventative measure against cancer, heart disease, diabetes, hepatitis, and infectious diseases. However, the majority of studies are conducted with ethanolic extracts. This study depicts the in vitro effect of aqueous MO leaf extract on human neuronal SH-SY5Y.
MO extract was prepared by soaking leaves powder in hot water to mimic consumers' daily consumption as a hot tea. The viability of MO-treated cells at conc. 0.01%-0.08% was tested using MTT and trypan blue exclusion assays at 24 and 48 hours. Changes in reactive oxygen species (ROS), NADPH, and ATP levels in treated cells were measured using NBT, NADPH, and ATP luminescence assays respectively. The possible protective effect of pre-/ or co-treatment of antioxidants NAC, MitoQ, and catalase with MO was determined. Molecular docking was conducted on phytochemicals found within MO (quercetin, gallic acid, p-coumaric acid, and 4-hydroxy 3-methoxy cinnamic acid) and their interaction with antioxidant enzymes (SOD, NOX, CAT, & GR).
Treatment of SH-SY5Y cells with MO extract (24 and 48 hours) induced a dose- dependent, time-independent a) decrease in viability by 85% to 25%, b) increase in ROS by ~5% to ~60% at conc. of 0.02%-0.03% respectively, with c) a preliminary decrease in ATP levels. In addition, at MO % ≤ 0.02, an increase in NADPH levels was obtained in a time-dependent manner that maintained ROS levels. However, pre-/ co- treatment with antioxidants NAC, MitoQ, and catalase exhibited no protective effect in restoring viability. Following this, the docking of the phytochemicals with antioxidant enzymes had negative binding affinities, with quercetin demonstrating the highest affinity. Three of the antioxidants (NOX, SOD & GR) displayed binding affinity with all phytochemicals except catalase, which only had affinity with quercetin.
In essence, MO treatment exerted a cytotoxic effect on SH-SY5Y cells. While glial cells (N9) were more sensitive, the neuronal cells illustrated a higher sensitivity compared to previously tested cell lines (A549, CaCo2, HepG2). The dose-dependent decrease in viability may be attributed to the increase in ROS levels, which were in line with our previous findings on other cell lines. The increase in NADPH levels may have resulted from a) the inhibition of NADPH oxidases (NOX) by one or more MO
2
components, b) the activation of antioxidant enzymes, and c) the differential inhibitory or stimulatory effect (Km, Vmax) of various MO components on pro/ anti-oxidant metabolic enzymes. Our findings in molecular docking using the computational analysis tool PyRx indicate favorable interactions between phytochemicals and pro/ anti-oxidant enzymes. Future metabolomics will further elucidate the metabolite profiles of different pathways in MO-treated compared to non-treated neuronal cells
Downregulation of hsa_circ_0005654 Triggers Tumor Initiation Events in Non-Neoplastic Mammary Epithelial Cells: Relevance as a Biomarker for Early Breast Cancer Detection
Get PDFIn the latest report for 2020, breast cancer (BC) had the highest incidence rate of 2.26 million cases. Ranking in the top 5 cancers for mortality, it caused 685,000 deaths. Late diagnosis as well as lack of regular screening contribute to the high death toll, especially for populations at risk. With the shortcomings of regular screening methods to detect early breast tumorigenesis and the invasiveness of biopsy screening, studies have redirected their efforts towards the utilization of body fluids for detection.
CircRNAs and miRNAs are non-coding RNAs that have been shown to be involved in BC initiation and progression. CircRNAs mimic the expression of their parental gene, and may target certain miRNAs by a sponging mechanism, which produces reciprocal expression between circRNAs and their target miRNA. Using large data RNAseq (mRNA and miRNA) analysis of stage I breast cancer patient samples and multiple bioinformatic tools, our lab identified 57 gene/circRNAs/miRNA/mRNA axes that are predictive of BC. Due to their novelty, data on circRNAs was lacking and their expression in stage 1 BC remained predicted in the axes. To increase our understanding of the involvement of the proposed circRNAs in BC initiation, this study aimed to conduct in-vitro investigation of selected circRNAs from the 57 circRNAs. None of the 34 downregulated circRNAs in the BC predictive axes were previously studied for their role in BC. Literature review allowed the selection of six downregulated circRNAs that have been reported to be downregulated in other types of cancer: hsa_circ_0005654, hsa_circ_0004075, hsa_circ_0005450, hsa_circ_0087302, hsa_circ_0006539, and hsa_circ_0029405. We downregulated the expression of the six circRNAs in nontumorigenic human mammary epithelial HMT-3522 S1 cells using transient transfection of junctional-specific siRNA. Proliferation assay post transfection revealed an increased proliferation by day 3 when targeting hsa_circ_0005654. Based on this finding, and that hsa_circ_0005654, proposed within the axis PRDM5/hsa_circ_0005654/miR-183, is one of the higher confidence axes, it was selected for further studies. Downregulation of hsa_circ_0005654 in S1 cells was verified by qRT-PCR using divergent primers showing a 0.5-fold expression in si5654 (siRNA targeting hsa_circ_0005654) transfected relative to sham transfected cells. The expression of the parental gene PRDM5 of hsa_circ_0005654 was comparable between un-transfected, si5654 transfected, and sham transfected S1 cells. Downregulation of hsa_circ_0005654 expression led to enhanced migration of S1 cells (~3.2 folds in si5654 transfected compared to sham transfected cells) and disruption of lumen formation in 3D cultures (~0.5-fold decrease compared to sham transfected cells). Moreover, we showed that hsa_circ_0005654 triggers a reciprocal upregulation of its target miRNA miR-183 (~3.2 folds increase compared to sham transfected cells). To establish a model that can be used for future long-term and 3D studies, we stably downregulated hsa_circ_0005654 in S1 cells using the lentiviral system and verified its downregulation using qRT-PCR (~0.2 fold decrease compared to sham transfected cells). These in-vitro studies further reaffirmed the involvement of circRNA hsa_circ_0005654 in BC initiation as proposed in the BC predictive axes. Future studies in our lab aim to screen for the 57 circRNA and respective target miRNAs from the axes in stage I BC blood samples of patients. For this purpose, we aimed to optimize the detection of circRNAs using qRT-PCR in this study. Treatment with RNase R did not achieve earlier detection of hsa_circ_0005654 as expected and showed delayed CT values in qRT-PCR. We opted for a second approach, independent of RNase R. We found that the use of 20-fold lower concentration of total RNA and random primers in reverse transcription could possibly allow for the detection of differential circRNA trends efficiently.
In conclusion, our findings provide insight into the role of hsa_circ_0005654 as tumor suppressor in the breast epithelium, whereby its downregulation is associated with tumor initiation events in non-neoplastic mammary epithelial cells possibly through sponging miR-183. We also proposed a method for the efficient detection of circRNAs using qRT-PCR to be utilized for the screening of circRNAs in blood samples
Elementary Teachers' and School Counselors’ Perceptions of the Effectiveness of School Counseling: The Case of an Inclusive Lebanese Private IB School
No full textSchool counselors play a vital role in the learners’ life. Students require guidance and
support in their development, not only on their academic achievement. These
developments include interpersonal relationships, self-esteem, emotion management,
conflict resolution, etc., especially during the elementary level (Hines et al., 2020).
Previous research studies have examined the school counselor’s services and teacher’s
perspectives for the counseling service instead of the impact and effectiveness of school
counselors in Lebanon (Ayyash- Abdo et al., 2010; Khansa, 2015).
The purpose of this study was to explore elementary teachers' and school counselors’
perspectives of the effectiveness of the school counseling program. In addition, the study
explored the nature of collaboration and communication between the school counselors
and teachers. The research design was qualitative research and the researcher applied
semi-structured interviews for data collection. The researcher analyzed the data by
applying Braun and Clarke’s (2006) thematic analysis.
The sample size of the study was composed of three elementary teachers and one
elementary school counselor in an inclusive, private IB school case study. The rationale
for focusing on an IB school is that the IB system focuses on wellbeing and applies a
holistic approach in supporting the learners’ learning experience and development.
The results demonstrated that the participants perceived the school counseling program
as effective, and they provided recommendations on how the counseling program can
improve to enhance its effectiveness. Moreover, the findings revealed that
communication and collaboration play a crucial role between the teachers and counselor
to better support the student’s according to their individual needs and to set an effective
intervention action plan
Alginate Sulfate Polycaprolactone Nanoparticles For 5-Fluorouracil Anti-colorectal Cancer Drug Encapsulation
No full textNanoscaled drug delivery systems have great potential in cancer applications, especially for chemotherapy drugs where nanoparticles (NPs) protect the drug from rapid metabolism and increase its lifetime. The anticancer chemotherapy drug 5-fluorouracil (5-FU) has a very short half-life with high toxicity. To overcome this drawback, 5-FU is incorporated into many types of NPs such as lipid, inorganic and polymeric NPs. Alginate sulfate (AlgSulf) is a synthetic mimic of sulfated glycosaminoglycans that can enhance the NP's properties in terms of drug protection and sustained release. Moreover, previous work from our group demonstrated the anticancer properties of AlgSulf on breast cancer and lung adenocarcinoma cells. Therefore AlgSulf/polycaprolactone (PCL) nanoparticles could enhance 5-FU delivery and therapeutic effect by enhanced drug protection and sustained release and could also work in synergy with 5-FU to decrease cancer cell proliferation. In this thesis, we report for the first time the preparation and evaluation of AlgSulf/PCL polymeric NPs loading 5-FU. We prepared double emulsion NPs using high molecular weight PCL containing respectively 0.5%, 1% and 2% concentrations of AlgSulf, 0.5% pure alginate (Alg) and one without AlgSulf nor Alg (PCL NP) and characterized them by particle size, polydispersity index (PDI), zeta potential analysis, drug encapsulation efficiency (%EE), scanning electron microscopy (SEM), attenuated total reflectance (ATR), X-ray powder diffraction (XRD), and release in plates assessment. We also assessed their stability in terms of size and PDI and their effect on HCT116 human colorectal cancer cell by Sulforhodamine B (SRB) and trypan blue assays when loaded and unloaded with 5-FU. AlgSulf was also evaluated in its free form on HCT116 cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H- tetrazolium bromide (MTT) assay to assess AlgSulf anticancer effect. The NPs were stable up to three weeks with a size of 200 nm, low PDI, and negative zeta potential which render them suitable for drug delivery. SEM images showed well-defined spherical NPs, and the encapsulation efficiency ranged from 13.82% to 18.28%. All NP’s presented the peaks of 5-FU functional groups when assessing them using ATR, the crystal structure of all NP’s surface did not change by adding 5-FU which indicates that 5-FU is encapsulated in the NPs in an amorphous way. The SRB assay revealed a decrease in HCT116 cell growth whether in non-loaded NPs or loaded with 5-FU for up to 72 hours, with 0.5% AlgSulf loaded with 5-FU NP showing the greatest anticancer effect for a concentration of 25 μM at 72h (P<0.0001). The acquired inhibition in cell proliferation when employing the NPs was less than that of free 5-FU. This may be explained by the results of the release in plate assay which showed a slow release of PCL after 3 days of incubation for the 0.5% AlgSulf NP. The trypan blue exclusion assay confirms that utilizing 0.5% AlgSulf in the NPs core had a more potent anticancer effect compared to higher concentrations of AlgSulf. The current work demonstrates the potential of combining AlgSulf/PCL NPs with chemotherapy drugs like 5-FU for sustained drug release and enhanced cancer therapy. Additional in vitro and in vivo testing are needed to refine the NP formulation and assess its efficacy on healthy and drug-resistant cancer cells
The Impact of Phosphorus on Carbohydrate Metabolism and Core Body Temperature
No full textThe increasing prevalence of obesity has coincided with a shift towards diets high in refined, nutrient-poor carbohydrates that are low in Phosphorus (P). Previous studies demonstrated that P attenuates postprandial glycemia and suppressed appetite in healthy individuals. Glucose dips were also reported to influence food intake. In addition to that, the thermostatic theory suggests that heat generated from ATP hydrolysis modulates food intake. Thus, this study was devised to investigate the impact of P on postprandial glucose dynamics, core body temperature (CBT) and appetite, while concurrently exploring the potential correlation among these variables.
A single-blinded crossover study was conducted over 10 days with a two-day washout period between the different treatments (P and placebo). Overnight fasted healthy subjects (n=16) were asked to consume a 600-kcal low P meal, along with either P (600mg) or placebo tablets in a random order. Blood glucose was monitored using the continuous glucose monitoring Dexcom G6 system, CBT was monitored using the research CORE Greenteg device and subjective appetite scores were assessed using validated visual analogue scale (VAS) questionnaires for 2 hours post-meal ingestion.
Phosphorus ingestion significantly decreased post-prandial (0-90min) blood glucose levels (p<0.008) and significantly increased AUC CBT (0-90min) (p<0.05). This was paralleled by a decline in appetite scores. Furthermore, a significant correlation between changes in CBT and satiety was observed in the placebo group (r=0.309, p<0.000) and this correlation persisted in the meal containing P (r=0.336, p<0.000), in addition to a significant association observed between glucose and appetite scores in the P group.
Our findings suggest a possible role of P ingestion in decreasing food intake partially by increasing CBT. This study also confirms the role of P in reducing postprandial glycemia, thereby potentially contributing to the prevention and the management of obesity
National Identity in Lebanese Civics Textbooks: A Foucauldian Discourse Analysis
Get PDFThis thesis examines the creation of national identity in Lebanese civics textbooks using Foucauldian discourse analysis. Building on Foucault's theories of power, knowledge, and discourse, the research investigates how narratives of Lebanese national identity are formed, transmitted, and reinforced in the educational system. By evaluating the discursive processes encoded in these textbooks, the study sheds light on how power dynamics develop and preserve certain understandings of national identity. The study uses a qualitative examination of chosen textbooks to discover the methods by which dominant ideologies are inscribed, challenged, and negotiated within the educational curriculum. Furthermore, it looks at the effects of these discursive constructions on subjectification, citizenship, and social cohesiveness in Lebanon. Finally, this study adds to a better understanding of the complicated interplay between education, power, and identity in the Lebanese context, as well as insights into larger discussions about nationalism, education, and discourse analysis