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Respiratory retention of 35 toxicants from e-cigarette gaseous emissions: comprehensive numerical study

Research Abstract
Electronic cigarettes can generate multiple carcinogenic substances and damage respiratory epithelial cells. The absorption mechanisms of e-cigarette toxicants throughout the puffing session remain poorly understood owing to ethical constraints associated with subjective experiments. This study provides an alternative computational method that integrates computational fluid dynamics and physiological pharmacokinetic models to predict respiratory retention rates (Ri). The results show that the arithmetic average retention of 35 substances is 62.2 %, whereas the mass-weighted average retention rate is 86.7 %, which is induced by high-mass-fraction toxicants such as glycerol, nicotine, formaldehyde, and acetaldehyde. This suggests that a considerable proportion of e-cigarette compounds is exhaled, thus reflecting the risk of passive smoking. Diffusivity in air (Da) is not a universal predictor of Ri but is highly relevant for soluble compounds. However, solubility in the watery mucus layer is the primary determinant of Ri for all examined constituents, thus reflecting the logarithmic correlation between Ri and the partition coefficient between mucus and air (Pm:a). We demonstrate the nonlinear relationship between physicochemical properties and respiratory uptake by combining Da and Pm:a, thereby facilitating the prediction of Ri. Simulation of vaping behavioral factors reveals that exhalation through the nostrils can increase Ri by 7 %–12 % compared with oral-only exhalation owing to more significant substance–tissue interactions in the complex passages of the nasal cavity. This model is promising for future health-risk assessments and regulatory decisions aimed at limiting e-cigarette usage.

 
Research Authors
Islam Mohamed Sayed Abouelhamd, K Kuga, T Mansuy, Kazuhide Ito
Research Date
Research Journal
Building and Environment
Research Pages
113663
Research Publisher
Elsevier
Research Rank
Q1
Research Vol
285
Research Website
https://www.sciencedirect.com/science/article/abs/pii/S0360132325011345
Research Year
2025

Experimental and computational predictions of odorant transport dynamics from indoor environment to olfactory tissue

Research Abstract

The intricate dynamics of odorants in the indoor environment and human respiratory system remain poorly understood. In the present study, we integrate odor sensory tests (OSTs) and computational fluid dynamics coupled with a physiologically based pharmacokinetic (CFD-PBPK) model to elucidate various aspects of odorant transport and olfaction dynamics. Safe yogurt-derived substances were incorporated into OSTs to prevent harmful exposure. Acetaldehyde was identified as a key active component in determining odor intensity, prompting further analysis of acetone and other four constituents. Logarithmic correlations were established between the perceived odor intensity from the OSTs and both time-averaged absorption flux and equilibrium concentration within the olfactory mucus layer. These parameters were numerically captured, enabling the logarithmic approximation of odor intensity for different breathing profiles and developing reliable prediction models for odor sensation in the indoor environment based on quantifiable physiological parameters. Location-specific analysis revealed the nostrils and olfactory regions as the most accurate indicators of perceived odor intensity, proving the limitations of rough sensory assessments in the indoor/breathing zone scales. This study offers insights for potential safe and sustainable applications, such as smart odor displays, e-noses, and sensors/control systems in the indoor environment, particularly for long-term exposure in industries that emit harmful compounds.

Research Authors
Islam Mohamed Sayed Abouelhamd, K Kuga, K Saito, M Takai, T Kikuchi, Kazuhide Ito
Research Date
Research Journal
Sustainable Cities and Society
Research Pages
106397
Research Publisher
Elsevier
Research Rank
Q1
Research Vol
126
Research Website
https://www.sciencedirect.com/science/article/abs/pii/S2210670725002732
Research Year
2025

Ellipsoidal K-Means: An Automatic Clustering Approach for Non-Uniform Data Distributions

Research Abstract

Traditional K-means clustering assumes, to some extent, a uniform distribution of data around predefined centroids, which limits its effectiveness for many realistic datasets. In this paper, a new clustering technique, simulated-annealing-based ellipsoidal clustering (SAELLC), is proposed to automatically partition data into an optimal number of ellipsoidal clusters, a capability absent in traditional methods. SAELLC transforms each identified cluster into a hyperspherical cluster, where the diameter of the hypersphere equals the minor axis of the original ellipsoid, and the center is encoded to represent the entire cluster. During the assignment of points to clusters, local ellipsoidal properties are independently considered. For objective function evaluation, the method adaptively transforms these ellipsoidal clusters into a variable number of global clusters. Two objective functions are simultaneously optimized: one reflecting partition compactness using the silhouette function (SF) and Euclidean distance, and another addressing cluster connectedness through a nearest-neighbor algorithm. This optimization is achieved using a newly-developed multiobjective simulated annealing approach. SAELLC is designed to automatically determine the optimal number of clusters, achieve precise partitioning, and accommodate a wide range of cluster shapes, including spherical, ellipsoidal, and non-symmetric forms. Extensive experiments conducted on UCI datasets demonstrated SAELLC’s superior performance compared to six well-known clustering algorithms. The results highlight its remarkable ability to handle diverse data distributions and automatically …

Research Authors
Alaa E Abdel-Hakim, Abdel-Monem M Ibrahim, Kheir Eddine Bouazza, Wael Deabes, Abdel-Rahman Hedar
Research Date
Research Department
Research Journal
Algorithms
Research Member
Research Pages
551
Research Publisher
MDPI
Research Vol
Volume 17, Issue 12
Research Website
https://scholar.google.com/scholar?oi=bibs&cluster=1136932969198565742&btnI=1&hl=en
Research Year
2024

Dynamic Deployment of Mobile Roadside Units in Internet of Vehicles

Research Abstract

Mobile roadside units have crucial role in ensuring efficient communication, computing, and caching services in internet of vehicles (IoVs) for vehicles traversing urban landscapes. The dynamic nature of urban environments faces challenges in optimizing the deployment of mRSUs to adapt to varying vehicular densities and traffic patterns in real-time. In this article, we propose a novel real-time optimization approach for the dynamic deployment of mobile Roadside Units (mRSUs) in urban environments to support the rapid growth of the IoV. The proposed method is a novel allocation strategy based on Minimum Dominating Set (MDS) theory, which is demonstrated to significantly reduce the number of mRSUs required. This reduction is achieved without compromising the efficiency and effectiveness of the network, thereby ensuring rapid and reliable communication within the IoV. This approach addresses critical …

Research Authors
Alaa E Abdel-Hakim, Wael Deabes, Kheir Eddine Bouazza, Abdel-Rahman Hedar
Research Date
Research Department
Research Journal
IEEE Access
Research Member
Research Pages
155548-155534
Research Publisher
IEEE
Research Vol
12
Research Website
https://scholar.google.com/scholar?oi=bibs&cluster=9429625967726641888&btnI=1&hl=en
Research Year
2024
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