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    Amplicon-Based Metagenomic Assessment of the Skin Microbiota in a Healthy Middle Eastern Cohort: The Lebanese Population
    Korban, Joelle; Bilen, Melhem; Kurban, Mazen; Abou Kheir , Wassim; Abou Fayad , Antoine; Saba , Esber; MSBS; Department of Experimental Pathology, Immunology and Microbiology; Faculty of Medicine; American University of Beirut
    Background: Skin microbiota is a complex ecosystem that plays an important role in immune system regulation, skin homeostasis and protection against pathogens. The composition of skin microbial communities is affected by recipient genetics, environmental factors, geography and lifestyle factors. Although the skin microbiota has lately been studied in many populations, studies on the Lebanese population remain limited, which has a distinct genetic and environmental variety. Aim: This study seeks to characterize the cultivable/enrichment-biased skin microbiota of Lebanese individuals under controlled culture conditions. By identifying the prevalent bacterial taxa and patterns of diversity after pre-enrichment, this study provides an initial reference framework for future research into dermatological issues in the Lebanese population and the role of microbial dysbiosis in disease. Methods: Forehead skin swabs were collected from fourteen healthy Lebanese individuals, with no known skin disorders. These samples were pre-enriched in aerobic hemoculture bottles at different temperatures due to the low microbial biomass of skin samples and insufficient DNA yield for direct sequencing. While this approach enabled successful amplification and sequencing, it may have introduced a selection bias favoring fast-growing and aerotolerant microorganisms. DNA was extracted and sequenced for 16S rRNA genes using the Illumina MiSeq platform. Bioinformatics tools were then used to determine taxonomic composition, and alpha diversity indices across the included samples. Results: In this study, at the phylum level, Bacillota was detected across the enriched samples, whereas Actinomycetota and Pseudomonadota were detected in fewer samples. At the genus level, Staphylococcus was most consistently detected across samples, including common commensal species, while several environmental-associated taxa were also detected. In addition, alpha diversity indices showed variability in evenness, richness and dominance among the enriched samples. Conclusion: This study helps to address an important regional knowledge gap in the Middle East, by providing an initial characterization of cultivable/enrichment-biased skin microbiota of Lebanese individuals. The results show marked inter-individual variability, as well as shared patterns across individuals. This study highlights the need for region-specific studies and may serve as a reference for future research studying skin disease such as atopic dermatitis (AD), psoriasis, and acne in Lebanon.
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    Respiratory Tract Microbiota in Electronic Nicotine Delivery System Users: Insights into Microbial Shifts and Health Implications
    El Tawil, Ali; Bilen , Melhem; Matar, Ghassan; Abou Fayad, Antoine; Zouein, Fouad; Saba, Esber; MSBS; Department of Experimental Pathology, Immunology, and Microbiology; Faculty of Medicine; American University of Beirut
    Introduction: The respiratory microbiota is an important component of airway health and immune defense. Although the effects of conventional, tobacco smoking on respiratory microbial communities are well documented, the impact of electronic nicotine delivery systems (ENDS), such as e-cigarettes and heated tobacco products, remains less clear. Given the growing use of these products in Lebanon, this study investigated the respiratory microbiota of Lebanese ENDS users compared with healthy controls. Methods: In this study, expectorated sputum samples were collected from adult healthy never-smokers and electronic nicotine delivery systems (ENDS) users residing in Lebanon following the Institutional Review Board approval and written informed consent. Bacterial genomic DNA was extracted from sputum using the QIAamp UCP Pathogen Mini Kit, purified with the ZymoBIOMICS cleanup kit, and assessed for concentration and purity by NanoDrop spectrophotometry. The V3-V4 hypervariable region of the 16S rRNA gene was amplified and sequenced on the Illumina MiSeq platform. Raw paired-end reads were quality filtered and denoised using TrimGalore and the DADA2 plugin in QIIME2, and taxonomic classification of amplicon sequence variants was performed using a naïve Bayes classifier trained on the Greengenes 16S rRNA database. Results: Alpha diversity did not differ significantly between ENDS users and non-smokers for Chao1 (H = 1.033, p = 0.310), Shannon (H = 0.314, p = 0.576), Pielou’s evenness (H = 0.314, p = 0.576), or Simpson diversity (H = 0.589, p = 0.442). Jaccard beta diversity was likewise not significantly different (PERMANOVA pseudo-F = 1.118, p = 0.062). Both groups showed similar phylum-level profiles dominated by Bacillota. In contrast, significant differences were detected at lower taxonomic levels, with Actinomyces (p < 0.0001) and Nanosynbacter (p = 0.0329) differing at the genus level and Rothia sp001808955 differing at the species level (p = 0.0002). These results indicate selective taxonomic shifts in ENDS users despite broadly preserved overall community diversity and structure. Conclusion: In this Lebanese cohort, ENDS use was associated with selective, fine-scale shifts in the expectorated sputum microbiota rather than community-wide disruption. While overall microbial diversity and community structure remained largely preserved, differences at the genus and species levels suggest that ENDS exposure may subtly influence specific respiratory microorganisms. ENDS usage may foster a microflora environment with increased biofilm-forming capacity and pro-inflammatory status, with reduced colonization resistance. Longitudinal. Larger studies with higher-resolution analyses are needed to clarify the biological and clinical significance of these changes.
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    Impact of Covid 19 Amid Multilayered Crisis on Social and Emotional Behaviors of Preterm Children and Parental Practices: Cross-Sectional Study from Lebanon
    Charafeddine, Lama; Nabulsi, Mona; Barakat, Marc; Tamim, Hani; MS; Scholars in HeAlth Research Program; Faculty of Medicine; Faculty of Health Sciences; American University of Beirut
    Background: Early childhood development is highly sensitive to the quality of nurturing care, with parental mental health and caregiving practices playing a crucial role. In Lebanon, the COVID-19 pandemic overlapped with severe national crises—economic collapse, political instability, and the 2020 Beirut port explosion—intensifying risks for young children and their families. Preterm infants, already at elevated developmental risk, remain an understudied group in terms of how these compounded adversities have affected their socio-emotional development and caregiving environments. Objective: This study aimed to compare the social-emotional outcomes, parenting behaviors, and parental stress levels between families of preterm and term-born children within the context of the COVID-19 pandemic and the August Beirut blast. Methods: This cross-sectional study conducted between 2022 and 2024 targeted 224 participants, including 114 parents of term children and 110 parents of preterm children (mean gestation 32.21 weeks) recruited from private and governmental hospitals. Validated instruments included the Ages and Stages Questionnaires: Social-Emotional (ASQ-SE-2) for social-emotional behavior, UNICEF MICS 6 for parenting activities, the Parenting Stress Index-Short Form (PSI-SF), and a Parent-Child Relationship (PCR) scale. Inferential statistical analyses used SPSS version 31. Results: Preterm children exhibited significantly higher social-emotional developmental delay (23.6%) compared to term children (7.0%, p<0.001). Preterm children were also more likely to be affected physically or emotionally by the Beirut blast (12.7% vs. 3.5%). Interestingly, parents of preterm children engaged in more frequent developmental activities (64.5% vs. 39.5%, p<0.001), yet reported significantly lower quality in the parent-child relationship regarding closeness and affection: the PCR score for parents of preterm children was significantly lower (26.06/30 vs. 27.41/30, p-value 0.004). Furthermore, parents of preterm children reported significantly higher stress levels (79.62 vs. 69.93, p<0.001), with 32.7% scoring in the clinical referral range. Stepwise linear regression explained 40.9% of the variance in social-emotional outcomes, identifying preterm status (β =12.66, p =0.001), elevated parental stress (β =1.05, p<0.000), and the child’s acquisition of new skills (β =-5.588, p=0.009) as the primary predictors of behavioral scores. Conclusion: Prematurity is associated with higher risk of social-emotional vulnerabilities, which are exacerbated by clinical levels of parental stress despite high levels of parental engagement. These findings highlight the critical need for multi-dimensional screening and family-centered interventions that address both child development and parental mental health in high-risk populations.
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    A Multistage Game in an Off-Grid Microgrid Market: A Non-Cooperative Game Theoretic Approach
    Abu Hejjeh, Mohammad; Olleik, Majd; Zaccour, Georges; Maddah, Bacel; MEM; Department of Industrial Engineering and Management; Maroun Semaan Faculty of Engineering and Architecture; American University of Beirut
    Although national grids are commonly responsible for ensuring reliable electricity, decentralized solutions became crucial alternatives, especially in isolated locations or when grid availability is uncertain. Furthermore, critical facilities that can not withstand interruptions in electricity supply often rely on off-grid microgrids. The existing literature has extensively addressed off-grid microgrids, particularly in centralized decision-making frameworks while allowing multi-stage investments, but as the complexity of electricity systems has increased and with the rise of prosumers (agents who produce and consume electricity), the suggested centralized solution approaches have become questionable. This thesis develops and analytically solves a game-theoretical model for an off-grid microgrid consisting of multiple heterogeneous agents while tackling multi-stage investment planning. The model studies the interactions and behavior of four major participants: a dispatchable source of supply, household prosumers, household consumers, and a neutral microgrid operator. The thesis investigates the existence and uniqueness of a Nash Equilibrium while proving its equivalence to a welfare maximization problem. The model is utilized to implement different pricing mechanisms that can be exercised by the neutral microgrid operator and then applied to a Lebanese case study. The results show that achieving cost-reflective and efficient prices requires the presence of a neutral operator that controls the rates of return of the dispatchable source of supply and household prosumers. Both household consumers and prosumers prefer to satisfy their demand through the grid and have no shortage. The results further reveal a complementarity pattern in which the dispatchable source of supply dominates the night-time supply and price formation, while household prosumers determine their optimal size of photovoltaic systems to meet the total day-time demand in the grid.
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    A Multiphysics Modeling Framework for Productivity Enhancement in Solar Stills
    Abou Ali, Hashem; Yehya, Alissar; Ayoub, George; Moukalled, Fadl; Harb, Mohammad; Zayyat, Ramez; ME; Department of Mechanical Engineering; Maroun Semaan Faculty of Engineering and Architecture; American University of Beirut
    Water scarcity remains a critical global challenge, particularly in arid and semi-arid regions, where access to clean water is limited. Solar stills offer a simple and sustainable desalination solution; however, their productivity is inherently low. This study presents a multiphysics modeling framework to investigate passive enhancement strategies for solar still systems, capturing the coupled heat and mass transfer processes governing evaporation, including conduction, buoyancy-driven convection, radiation, and phase change. The analysis focuses on the integration of vertical rods and wick-assisted evaporation to enhance heat redistribution and effective evaporation area. A detailed parametric study was conducted to evaluate the influence of rod geometry, wick thickness, surface emissivity, and material properties on system performance. The results show that productivity is primarily governed by the effective evaporation area rather than temperature alone, with the optimized configuration increasing the evaporation area by 86%. This configuration achieved productivity enhancements of up to 84% under fall conditions and 97% under winter conditions. Seasonal analysis revealed that the enhancement mechanism is more pronounced under low solar radiation, where the wick acts as an additional heat-absorbing surface, while under high radiation conditions the basin water becomes the dominant driver of evaporation. An economic evaluation demonstrated that the optimized design reduces the cost of produced water from 0.14 USD/L to approximately 0.113 USD/L. These findings confirm that the proposed passive enhancement is technically effective and capable of reducing the cost of water production in solar desalination systems.