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Photocatalytic Degradation of Tetracycline Antibiotic by Titania Photocatalyst under Visible Light
No full textAntibiotics (ABs) are antibacterial compounds used to treat bacterial infections both in humans and animals. Sub-therapeutic levels of antibiotics are also given to animals and poultry to promote growth. In agricultural environments, ABs reach croplands via animal manure used as fertilizer and/or AB-contaminated water used for irrigation. ABs can leach from soil and discharge from water treatment plants and eventually contaminate both surface and underground water. Tetracyclines (TCs) are among the most widely used ABs around the world due to their low cost and wide antimicrobial spectrum. In this work, we propose solar-mediated photocatalytic degradation system using titania (TiO2) photocatalyst as a promising, efficient, cost effective, and ecofriendly method to remove TCs from water streams. TiO2 is known for its super quantum yield, low cost, non-toxicity, hydrophilicity, high photoactivity, interesting charge transport properties, and good chemical and photostability. However, what restrict the use of TiO2 in large-scale applications include its large band gap energy of (3.2 eV) which limits its activation to mere UV light, complication of recovery from slurry reactors, and aggregation of its finely dispersed particles. To expand the activity of TiO2 into the visible light region and to enhance its adsorption capacity for TC, we explored its modification via sensitization with Fe ions and via immobilization over inert supports. Beta zeolite (BEA) and silicalite were used as zeolitic supports while nano-fibrous electrospun PVDF-HFP polymeric membranes were used to facilitate the recovery of titania from reaction medium. Metal organic framework (UiO66) was also prepared and used as a support to improve the surface area and adsorption capacity of TiO2. Two different metal sensitization techniques with Iron ions from aqueous solution of FeCl3 were explored. In the ion-exchange method, the substitutional cations within the TiO2/support structure were exchanged with Fe3+. Whereas, in the doping technique,
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solgel TiO2 was doped with Fe3+ during its synthesis and before its immobilization over support. Fe modified immobilized TiO2 catalysts were characterized using SEM, XRD, BET, UV-VIS DRS, TGA, and FTIR. The photocatalytic performance of the Fe-TiO2/support was evaluated under blue, white LED lights, and real solar irradiations for TC degradation. We also varied the reaction conditions (catalyst dosage, light power and wavelength, temperature, pH, and salt concentration) to optimize the operating conditions for TC photocatalytic degradation under visible light
Comparing Distalization Modalities in Minimizing Compact Bone Resistance: A Finite Element Analysis
No full textIntroduction: Orthodontic mini-implants have been utilized for Class II malocclusion correction by
distalizing the maxillary dentition through direct anchorage, where forces are applied
directly from the mini-implant to the teeth. Anatomical factors, such as compact bone,
have shown to create resistance to movement. A previous study by our group suggested
palatal placement of TADs to overcome this resistance. Finite element analysis (FEA)
provides a robust framework for simulating orthodontic forces and evaluating
biomechanical responses under controlled conditions.
Aims:
• Evaluate stress distribution within the periodontal ligament (PDL) and displacement
of teeth under three different TAD-supported distalization setups.
• Determine the setup that produces the greatest displacement while avoiding high
stresses.
• Determine the effect of adding a palatal force in reducing unwanted dental side
effects.
• Evaluate the impact of cortical bone properties, including stiffness, on stress
distribution and resistance to tooth movement.
Materials and methods:
A three-dimensional finite element model of the maxillary dentition was generated using
data from cone-beam computed tomography. Variations in cortical bone thickness and
stiffness were incorporated across 13 and 11 models, respectively. Three distalization
modalities were analyzed: buccal force (from a buccal miniscrew), palatal force (from a
palatal miniscrew), and combined bucco-palatal force. A force magnitude of 200 grams
was applied to the maxillary posterior segment, with stress evaluated at the periodontal
ligament (PDL) and displacement assessed at the occlusal surfaces of crowns and apices
of roots. The models were meshed and analyzed using ABAQUS software, and statistical
comparisons were made between different force magnitudes, distalization modalities,
and cortical bone variations.
Results:
Force application method significantly influenced stress distribution and tooth
displacement. Across all modalities, stress levels were highest at the canine and gradually
decreased posteriorly. The buccal modality resulted in greatest stress values on all
studied teeth, followed by the bucco-palatal, and then the palatal modality. Buccal force
application resulted in the least displacement among the studied dentition with the
greatest buccal tipping of the canine and posterior teeth, while palatal force produced
palatal tipping of the canine crown in the opposite direction. The combined bucco-palatal
force modality produced the greatest distalization with the least side effects.
Additionally, cortical bone stiffness affected tooth movement; models with stiffer
cortical bone exhibited lower displacement and higher stress concentrations, indicating
greater resistance to distalization.
Conclusions:
• The bucco-palatal modality demonstrated stress values at all teeth surfaces
intermediate between the buccal and palatal modalities, and greater displacement than
either of these setups. Accordingly, this combination would favor the bucco-palatal
approach to distalization of the maxillary teeth.
• While the buccal modality led to undesirable buccal tipping of the teeth, particularly
the canine, and the palatal modality yielded palatal crown and buccal root tipping of the
canine, combining buccal and palatal forces in the BP modality resulted in a more
controlled displacement pattern by reducing those side effects.
• The incorporation of individual mechanical properties in this study buttressed the
finding that cortical bone stiffness was a limiting factor in tooth distalization, further
underscoring the importance of steering the teeth away from cortical bone. This tenet
was achieved more with the BP modality. Moreover, thickness of the cortical bone did
not present resistance similar to bone stiffness.
• The application of 200 grams distalization force, compared with 150 grams in a prior
study by our research group, confirmed that greater forces lead to higher stress levels,
particularly in the posterior teeth and improved molar distalization.
• Future studies should focus on alternate distalization modalities in individualized CT
scans and time-dependent simulations. Clinical validation integrating finite element
analysis (FEA) with clinical data should allow for precise individualized predictions of
treatment outcomes
Methane Cracking for Hydrogen Production Using Bi-metallic Zeolites
No full textThe growing global energy demand and heavy reliance on fossil fuels have raised significant concerns about the finite nature of these resources and their detrimental environmental effects. These challenges underscore the urgent need to adopt sustainable energy alternatives that can meet global demands, ensure energy security, and keep global warming below the 2°C threshold set by the 2015 Paris Agreement. Hydrogen gas stands out as a promising alternative due to its high lower heating value (LHV) of 120 MJ/kg, surpassing that of conventional fuels like diesel, gasoline, and methane. However, current industrial-scale hydrogen production methods have multiple setbacks. Processes such as coal gasification and steam methane reforming generate greenhouse gases and require high operational temperatures, while dry methane reforming similarly demands high temperatures and produces CO as a byproduct, adding to the costs of hydrogen purification. Methane cracking offers a promising approach to hydrogen production without additional hydrocarbons, provided it employs a well-designed catalyst to facilitate the reaction at moderate operating temperatures (500–700°C). Operating at these temperatures reduces costs and creates opportunities to integrate solar energy, enhancing carbon neutrality. The efficiency of such a catalyst relies on the interaction between the active metal, promoters, and support. Therefore, developing a catalyst with balanced metal-support interactions is crucial to forming appropriately sized active metal particulates. This balance ensures high methane conversion rates and catalyst stability while minimizing deactivation. Nickel was selected as the active metal due to its affordability and effectiveness in methane cracking. Various parameters were investigated to optimize catalyst performance, including the choice of support materials, promoters, synthesis methods, and operating conditions. Among the tested supports, silica-alumina zeolites outperformed amorphous silica with promoters and mesostructured siliceous zeolites. Furthermore, mesoporous zeolites with wider pore structures exhibited superior performance, even with nickel loadings as high as 50%. These catalysts demonstrated not only excellent methane conversion rates but also significantly reduced deactivation, highlighting their potential for efficient and stable hydrogen production. After obtaining preliminary results from testing various catalysts, we focused on Ni-Zn/USY due to its notable performance advantages. Zinc-promoted nickel catalysts supported on Ultra-Stable Y (USY) zeolites were evaluated for methane pyrolysis. The unpromoted Ni/USY catalyst exhibited an initial conversion of 65.8%, which declined to 57.3% by the experiment's end. Introducing 5 wt% Zn as a promoter enhanced the conversion to 67.7% and maintained stable performance for 60 hours. XPS analysis suggested electronic interactions between Ni and Zn, while TPR and XRD revealed that Zn reduced the catalyst's metal-support interactions. The 50Ni-5Zn/USY catalyst demonstrated exceptional stability under increased reaction severity, including a temperature of 650°C, 80% methane inlet partial pressure, and a high gas hourly space velocity of 120 L/gcat.h. Spent catalyst analysis identified Ni-Zn carbides, which may have contributed to the improved activity, and significant quantities of highly graphitic, ordered multi-walled carbon nanotubes produced via a tip-growth mechanism, which likely prolonged the catalyst’s operational life. A detailed kinetic model for methane decomposition over a 50Ni–5Zn/USY catalyst was developed and validated. Experiments were conducted in a packed-bed reactor under atmospheric pressure, spanning temperatures of 500°C to 650°C and methane partial pressures from 0.225 to 0.8 bar. Several reaction mechanisms were evaluated, leading to the formulation of multiple kinetic models based on the Langmuir–Hinshelwood framework, with varying assumptions about the rate-determining step. The optimal kinetic parameters were identified using the fmincon algorithm in MATLAB combined with a multi-start search strategy to minimize the impact of initial guesses and avoid convergence to local minima. Constraints were incorporated to ensure zero reaction rate at equilibrium conditions, guaranteeing consistency with thermodynamic principles. Statistical techniques were applied for model selection, and additional validation was achieved using a packed-bed reactor model. The most suitable kinetic model indicates that the reaction proceeds via a dissociative adsorption mechanism, with the first hydrogen abstraction from methane identified as the rate-determining step. The activation energy, calculated as 80.9 kJ/mol, is consistent with previously reported literature values, reinforcing the reliability of the proposed model
al-Ṣināʿa in Late Ottoman Beirut: A Historical Study of an Arabic Concept
No full textThis dissertation investigates the Arabic notion of al-ṣināʿa in late 19th century Beirut. In identifying the concept’s semantic universe and layers of historical meanings, its material manifestations since the late 1860s, and the related reform project it prompted, I trace the emergence of al-ṣināʿa from the classical Arabic-Islamic corpus of knowledge into a modern field of inquiry. Thinking through al-ṣināʿa, I ask how historical actors in the Arab-Ottoman port-city connected knowledge and practice to modernity at the time of integration into the world-economy; in other words, how the cultural and literary revival of the period -the Nahda- was brought to bear on practice, material culture, and Arabic economic and scientific ideas. My study shows how a local culture of ṣināʿa emerged from the loci of the Nahda and propagated into the public sphere. In many ways, modern ṣināʿa designated a new configuration of knowledge and practice premised on utility, itself expressed in the language of patriotism and economic welfare in response to the European economic encroachment. Overall, I present al-ṣināʿa as an Arabic source concept that embodies the late 19th century Beiruti experiences of modernity and that speaks to hegemonic concepts that have so far served to depict histories of material culture in the Arab and Islamic worlds, such as Islamic art
Physics-Informed Neural Networks: an AI Approach to Solve Direct and Inverse PDE Problems
Full text linkPartial differential equations (PDEs) arise naturally when modeling physical phenomena mathematically. The importance of PDE goes far beyond just solving a math problem; they are crucial for many physics and engineering problems; saying that the world is governed by PDEs is not an exaggeration. However, solving a PDE is not always straight-
forward; despite their extreme importance, not all PDEs are solvable. Many numerical methods have been devised to solve PDEs over the years, like Finite Element Method, Finite Volume, etc.; nevertheless, these methods can suffer from numerical instability and being computationally expensive. Physics-Informed Neural Networks (PINNs) are a novel approach that uses the properties of deep learning to solve PDEs by combining AI and physics hand in hand without relying on traditional numerical discretization methods. In this thesis, we investigate the capabilities and limitations of PINNs in solving both di-
rect and inverse PDE problems. We introduce a novel architecture that can be adjusted to any PDE with any boundary/initial conditions. We also attempt to solve the Firn PDE, a very important and complex PDE. Our findings provide practical guidelines on the imple-mentation of PINNs across different PDEs, highlighting where PINNs succeed and may potentially fail. These findings suggest that PINNs have the future potential to be the go-to PDE solving method
Economic Evaluation of the Integration of E-Bikes in Sustainable Urban Areas
No full textElectrical assisted bicycles (E-bikes) are emerging as a promising and sustainable mode of transport for future smart cities, serving as a foundation to the evolving needs of urban mobility. This research explores the diverse realm of E-bikes, focusing on the motivations and barriers to their widespread adoption, with a specific emphasis on their economic aspects. E-bikes represent a compelling solution to contemporary transportation dilemmas, with the potential to increase accessibility, reduce greenhouse gas emissions, and enhance mobility for various populations, including the elderly and disabled. To fully comprehend their potential, this study investigates the four pivotal cost components affecting the integration of E-bikes: capital cost, operational cost, infrastructure cost, and externality cost. Capital costs include the initial investments in E-bikes production and distribution. Operational costs consider expenses related to maintenance and power supply. Infrastructure costs revolve around the development of E-bike friendly infrastructure, while externality costs apply to the broader environmental and health-related impacts associated with E-bike adoption. Through rigorous economic evaluation, this research seeks to quantify these costs and analyze their consequences. By identifying approaches for cost reduction, this study aims to support the integration of E-bikes and promote their wider adoption. The ultimate goal is to make E-bikes more affordable and accessible to a broader demographic, thereby increasing their market size and global market share, by evaluating the costs associated with the integration, adoption, and purchasing of E-bikes. This research intends to provide valuable insights and recommendations to policymakers, manufacturers, and the public, people purchasing and selling E-bikes, facilitating the smooth integration of e-bikes into the urban transportation landscape
Mixed Feelings: Emotional Labor in the Newsroom
No full textEmotion is one of journalism’s biggest dilemmas. The ideals of objectivity and neutrality
impose emotional labor on journalists. Alternative newsrooms in Lebanon question
notions of objectivity, neutrality and detachment, and open up a space for an alternative
ethics of emotion in journalism. However, emotional labor persists in these newsrooms.
In this thesis, I argue that journalists in Lebanon’s alternative newsrooms shoulder the
emotional burden of their labor individually, due to the absence of structural and
institutional attempts to address the problem of emotion. Through in-depth interviews
with five journalists working in alternative newsrooms, I found that questioning
objectivity does not automatically ease the tension towards emotion. Tactics of emotional
management impact the well-being of journalists in alternative newsrooms, while a
structural rethinking of emotionality is yet to be established
English as Capital vs. Language as Cultural: An Autoethnography of an Iranian Writer
No full textMENA Writing Studies Journal, vol. 1.1, Spring 2025, pp. 65-73Includes bibliographical references (pages 72-73)Scholarship on linguistic imperialism has explained the dominance resulting from
structural and cultural inequalities that put English language and culture above any
other (Phillipson, 1992). We can enrich the macro-level scholarship on this subject
by listening to the voices and complex experiences of individuals who are affected
by these histories of linguistic imperialism. To present more nuanced and situated
experiences, I narrate and analyze my own English writing journey as an Iranian
writer who learned English in Iran and is now a PhD student in Composition and
Rhetoric in the U.S., to trace the relationship between the ideologies of English as
capital and language as cultural. My autoethnography shows that the spread of
English is not inherently good or bad, but how it impacts its users depends on the
way it gets appraised against other languages. I consider culturally sustaining
pedagogy as an affirmative possibility, but also, my case shows that culturally
sustaining pedagogies can be complicated in contexts where there are conflicting
cultural values. I hope my multilayered experience in various contexts will induce
productive questions that will lead to a more capacious view of language and more
effective and inclusive writing pedagogies
A friend named Tucket
No full textA children's book, created by AUB students from the Education Department, for the course EDUC218 as a final project
Safeguarding Electoral Integrity in Lebanon: Revisiting the Role of the Supervisory Commission for Elections in Mitigating Online Disinformation
No full textProject. M.A.P.P.I.A. American University of Beirut. Department of Political Studies and Public Administration. Public Policy and International Affairs, 2025.In an era marked by the rapid acceleration of information flows, disinformation has
emerged as a significant threat to democratic processes worldwide. This project explores
the legal and institutional readiness of Lebanon to confront this challenge, focusing
specifically on the role of its Electoral Management Body (EMB) as defined in the 2017
Lebanese Electoral Law. Through a content analysis of publicly available documents,
including international frameworks developed by the United Nations Development
Programme (UNDP) and other global actors, as well as official Lebanese legal and
institutional materials, this research assesses existing regulatory gaps and normative
shortcomings in safeguarding information integrity during electoral cycles. By comparing
Lebanon’s current legal framework with global best practices, the study identifies areas
in need of reform and proposes legal and procedural amendments aimed at equipping the
EMB with the tools necessary to address disinformation effectively. The findings offer
some recommendations for enhancing the Lebanese electoral system’s resilience to
information pollution and contribute to the broader discourse on protecting democratic
institutions in the digital age