A Structural Engineer's Approach to Differential Vertical Shortening in Tall Buildings

Matar, Sami S.,Faschan, William J. Council on Tall Building and Urban Habitat Korea 2017 International journal of high-rise buildings Vol.6 No.1

Vertical shortening in tall buildings would be of little concern if all vertical elements shortened evenly. However, vertical elements such as walls and columns may shorten different amounts due to different service axial stress levels. With height, the differential shortening may become significant and impact the strength design and serviceability of the building. Sometimes column transfers or other vertical structural irregularities may cause differential shortening. If differential shortening is not addressed properly, it can impact the serviceability of the building. This paper takes the perspective of a structural engineer in planning the design, predicting the shortening and its effects, and communicating the information to the contractor.

Obstacles Facing Science Teachers regarding Distance Learning during the COVID-19 Pandemic in Saudi Arabia

Alessa, Matar Ahmed International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.3

This study aimed to explore science teachers' perceptions of obstacles that have affected their teaching during the COVID-19 pandemic. The sample comprised 204 science teachers in public schools within a Western district of Saudi Arabia. Results revealed that these teachers experienced obstacles across six areas: administration, students, teaching methods, assessment, technology, and learning aids. The study also explored teachers' perceptions of their current experience and offers suggestions for dealing with the identified obstacles.

Assessing the Success rate of e-Learning Systems Aadoption in Saudi Higher Education Institutions during COVID-19 Pandemic: Student Perspective

Aljuhani, Nouf,Matar, Zinah,Alzahrani, Asma,Saeedi, Kawther,Badri, Sahar,Fakieh, Bahjat International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.3

In response to the significant COVID-19 outbreak, countries have enforced the use of E-learning systems as an alternative to traditional learning; to contain the virus and minimize the infection rate while maintaining the continuity of the learning experience. However, the effective adoption of E-learning systems requires a well-understanding of critical factors, especially in times of crisis. In this regard, this study intends to assess the success of the E-learning system adoption by Higher Education Institutions (HEIs) during the crisis of COVID-19 by utilizing the Information Systems Success (ISS) model. This study's adopted model consists of nine interdependent dimensions, namely: Technical System Quality, Information Quality, Service Quality, Learner Quality, Perceived Satisfaction, Perceived Usefulness, System Use, Intention to Use, and System Success. An electronic survey was distributed among higher education students from different universities in Saudi Arabia to explore each model's dimension. Structural Equation Modeling (SEM) has been applied via SmartPLS software to test the causal relationships between dimensions. This study's main results revealed that students' Service Quality, Learner Quality, and the Intention to Use by students are essential drives for E-learning System Use during the Covid-19 pandemic. Meanwhile, the Intention to Use the system is significantly influenced by Perceived Satisfaction and Perceived Usefulness dimensions. Further, Perceived Satisfaction, Perceived Usefulness, and System Use are interdependent, and all three have a significant positive impact on E-learning System Success.

Endoscopic Findings in Children with Isolated Lower Gastrointestinal Bleeding

Ari Silbermintz,Manar Matar,Amit Assa,Noam Zevit,Yael Mozer Glassberg,Raanan Shamir 대한소화기내시경학회 2019 Clinical Endoscopy Vol.52 No.3

Background/Aims: Colorectal polyps are a common cause of lower gastrointestinal bleeding in children. Our aim was to study thecauses of isolated lower gastrointestinal bleeding and to analyze the characteristics of the colorectal polyps found in our cohort. Methods: We retrospectively reviewed colonoscopic procedures performed between 2007 and 2015. Children with isolated lowergastrointestinal bleeding were included in the study. Results: A total of 185 colonoscopies were performed for isolated lower gastrointestinal bleeding. The median patient age was 8 years,and 77 patients (41.6%) were found to have colonic polyps. Normal colonoscopy findings were observed and acute colitis was detectedin 77 (41.6%) and 14 (7.4%) patients, respectively. Single colonic polyps and 2–3 polyps were detected in 73 (94.8%) and 4 (5.2%) patientswith polyps, respectively. Of the single polyps, 69 (94.5%) were juvenile polyps, among which 65 (94.2%) were located in the left colon. Conclusions: Single left-sided juvenile polyps were the most common cause of isolated lower gastrointestinal bleeding in our study. Itwas rare to find multiple polyps and polyps proximal to the splenic flexure in our cohort. A full colonoscopy is still recommended in allpatients in order to properly diagnose the small but significant group of patients with pathologies found proximal to the splenic flexure.

Multiscale Modeling of Swelling Clays: A Computational and Experimental Approach

Dinesh R. Katti,Mohamed I. Matar,Kalpana S. Katti,Priyanthi M. Amarasinghe 대한토목학회 2009 KSCE Journal of Civil Engineering Vol.13 No.4

Expansive clays such as montmorillonite cause severe distress to infrastructure due to swelling. The swelling of montmorillonite clay is also the basis for its use in many commercial applications such as drilling muds in petroleum engineering, as landfill liners in environmental engineering and in making polymer clay nanocomposites. The focus of this work is to carry out a systematic experimental and numerical study to understand and model behavior of Na-montmorillonite at molecular and particulate level to find mechanism of swelling in the Na-montmorillonite interlayer. Experimental results show breakdown of particles with an increase in swelling of the clay. This phenomenon was numerically studied by developing a modified Discrete Element Method (DEM) model that incorporates the latest developments in both clay and computer science, and can simulate particle subdivision. DEM results show the role of particle subdivision on swelling and swelling pressure. In understanding the true mechanism of swelling, it is essential to incorporate the interactions between clay molecular structure and the interlayer water molecules. For bridging the length scales, we have also evaluated the stress deformation response of the clay molecular structure using Molecular Dynamic (MD) simulations. Simulation results show that the deformation in the clay molecular structure due to external stress is mostly due to deformation of the water molecules in the clay interlayer. A new experimental technique which enables us to capture the molecular changes in the clay molecular structure upon hydration is also developed. This work provides a foundation for multiscale modeling of swelling clays. Expansive clays such as montmorillonite cause severe distress to infrastructure due to swelling. The swelling of montmorillonite clay is also the basis for its use in many commercial applications such as drilling muds in petroleum engineering, as landfill liners in environmental engineering and in making polymer clay nanocomposites. The focus of this work is to carry out a systematic experimental and numerical study to understand and model behavior of Na-montmorillonite at molecular and particulate level to find mechanism of swelling in the Na-montmorillonite interlayer. Experimental results show breakdown of particles with an increase in swelling of the clay. This phenomenon was numerically studied by developing a modified Discrete Element Method (DEM) model that incorporates the latest developments in both clay and computer science, and can simulate particle subdivision. DEM results show the role of particle subdivision on swelling and swelling pressure. In understanding the true mechanism of swelling, it is essential to incorporate the interactions between clay molecular structure and the interlayer water molecules. For bridging the length scales, we have also evaluated the stress deformation response of the clay molecular structure using Molecular Dynamic (MD) simulations. Simulation results show that the deformation in the clay molecular structure due to external stress is mostly due to deformation of the water molecules in the clay interlayer. A new experimental technique which enables us to capture the molecular changes in the clay molecular structure upon hydration is also developed. This work provides a foundation for multiscale modeling of swelling clays.

Kidney Cancer in Lebanon: a Specific Histological Distribution?

Khafaja, Sarah,Kourie, Hampig Raphael,Matar, Dany,Sader-Ghorra, Claude,Kattan, Joseph Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.1

Background: Kidney cancer is the third most frequent urologic cancer in Lebanon after prostate and bladder cancer, accounting for 1.5% of all diagnosed cancers. In this paper, we report the histologic characteristics and distribution of kidney cancer, never described in Lebanon or the Middle East. Materials and Methods: Pathology results of operated kidney cancer were collected during a two year period (2010-2011) from two different Lebanese hospitals (Hotel-Dieu de France University Hospital and Saint Joseph Hospital). A total of 124 reports were reviewed and analyzed according to WHO classification of 2009. Results: The 124 patients diagnosed with kidney cancer had a median age of 62.4 [18-86], 75% being men and 25% women. Some 71 % of the lesions were renal cell carcinoma (RCC), 25.8% had a urothelial histology, 1.6% were lymphomas and 1.6% were metastases to the kidney. Patients having RCC had a median age of 60.3 [18-85], 77.3% were men and 22.7% women. Of the RCCs, 59.1% were clear cell carcinoma, 22.7% papillary, 11.4% chromophobic, 3.4% rom the collecting ducts of Bellini and 3.4% were not otherwise classified. Conclusions: Histological distribution of Lebanese kidney cancer seems unusual when compared to the literature. The percentage of urothelial renal pelvis tumors is strikingly high. Moreover, clear cell carcinoma accounts for only 59.1% of RCCS in contrast to the 75% described elsewhere, while papillary carcinoma represents more than 22.7% compared to 10%.

miRNA-200b Signature in the Prevention of Skin Cancer Stem Cells by Polyphenol-enriched Blueberry Preparation

Nawal Alsadi,Jean-François Mallet,Chantal Matar 대한암예방학회 2021 Journal of cancer prevention Vol.26 No.3

Exposure of the skin to solar UV radiation leads to inflammation, DNA damage, and dysregulation of cellular signaling pathways, which may cause skin cancer. Photochemoprevention with natural products is an effective strategy for the control of cutaneous neoplasia. Polyphenols have been proven to help prevent skin cancer and to inhibit the growth of cancer stem cells (CSCs) through epigenetic mechanisms, including modulation of microRNAs expression. Thus, the current study aimed to assess the effect of polyphenol enriched blueberry preparation (PEBP) or non-fermented blueberry juice (NBJ) on expression of miRNAs and target proteins associated with different clinicopathological characteristics of skin cancer such as stemness, motility, and invasiveness. We observed that PEBP significantly inhibited the proliferation of skin CSCs derived from different melanoma cell lines, HS 294T and B16F10. Moreover, PEBP was able to reduce the formation of melanophores. We also showed that the expression of the CD133+ stem cell marker in B16F10 and HS294T cell lines was significantly decreased after treating the cells with PEBP in comparison to the NBJ and control groups. Importantly, tumor suppressors’ miR-200s, involved in the regulation of the epithelial-to-mesenchymal transition and metastasis, were strikingly upregulated. In addition, we have shown that a protein target of the tumor suppressor miR200b, ZEB1, was also significantly modulated. Thus, the results demonstrates that PEBP possesses potent anticancer and anti-metastatic potentials and may represent a novel chemopreventative agent against skin cancer. Key Words Polyphenols, Cancer stem cells, Neoplasm metastasis, MicroRNA-200b, Zinc finger E-box binding homeobox 1

Theoretical rotational stiffness of the flexible base connection based on parametric study via the whale optimization algorithm

Mahmoud T. Nawar,Ehab B. Matar,Hassan M. Maaly,Ahmed G. Alaaser,Osman Hamdy 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.1

This paper handles the results of an extensive parametric study on the rotational stiffness of the flexible base connection using ABAQUS program. The results of the parametric study show the relation between the applied moment and the relative rotation for 96 different base connections. The configurations of the studied connections considered different numbers, diameters, and spacing of the anchor bolts along with different thicknesses of the base plate to investigate the effect of these parameters on the rotational stiffness behavior. The results of the previous parametric research used through the whale optimization algorithm (WOA) to detect different equation formulation of the moment-rotation (M-Ɵr) equation to detect optimum equation simulates the general nonlinear rotational behavior of the flexible base connection considering all variables used in the parametric study. WOA is a relatively new promising algorithm, which is used in different types of optimization problems. For more verification, the classical genetic algorithm (GA) is used to make a comparison with WOA results. The results show that WOA is capable of getting an optimum equation of the M-Ɵr relation, which can be used to simulate the actual rotational stiffness of the flexible base connections. The rotational stiffness at H/150 can be calculated using WOA (1) method and be used as a design aid for engineering design.

Outcome of Breast Cancer Screening: A Lebanese Single Institution Experience

Kourie, Hampig Raphael,Daher, Alain,Matar, Dany,Antoun, Joelle,Salloum, Lony,Kattan, Joseph Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.21

Background: Since 2002, from October till December of each year, the Lebanese Ministry of Public Health conducts a mammogram based breast cancer screening campaign in the whole country for women over 40 years of age. These mammograms are performed free of charge in governmental hospitals or for reduced fees in private hospitals. The aim of this study is to analyze the direct impact of this campaign on cancer detection and subsequent treatment. Materials and Methods: Radiologic records of women screened with a mammogram during the campaign period from October till December 2012 at Saint Joseph Hospital, Baouchrieh, Beirut, were reviewed. Results of mammograms were reported using the ACR score. Women with ACR score ${\geq}4$ were tracked and investigated. Results: 900 screening mammograms were performed; median age was 55.2 years (range:31-81 years). Some 826 (91.8%) had an ACR score of ${\leq}2$; 66 (7.3%) an ACR =3 and only 8 (0.89%) an ACR=4. Thus, less than 1% (8/900) of all screened women were considered at high risk and needed a close follow-up. Among these 8 women, 4 underwent surgery for an early breast cancer, one had synchronous metastatic breast cancer and two were lost to follow-up. Conclusions: To coclude, Among 900-screened women for BC, less than 1 % (8 out of 900) were at high risk of hiding a BC (ACR=4), half of them benefited from early therapy (4 women out of 900) and one was a false positive. Larger studies on national level should be accomplished to have a complete data on breast cancer screening in Lebanon. The results of these studies can affect the Lebanese health policy regarding BC.

Staphylococcus aureus derived hyaluronic acid and bacillus Calmette-Guérin purified proteins as immune enhancers to rabies vaccine and related immuno-histopathological alterations

Rania Ibrahim Shebl,Mohamed E. Amer,Tamer M. M. Abuamara,Emadeldin R. Matar,Hassan Fathy Ahmed,Tamer Albasyoni Gomah,Laila E. El Moselhy,Mohammed Abu-Elghait,Aly Fahmy Mohamed 대한백신학회 2021 Clinical and Experimental Vaccine Research Vol.10 No.3

Purpose: One of the essential goals regarding the successful control of rabies infection is the development of a safe, effective, and inexpensive vaccine. the current study aimed to evaluate the inactivation potential of β-propiolactone (βPL), binary ethyleneimine (BEI), and hydrogen peroxide (H2O2). Materials and Methods: Estimating the inactivation kinetics of βPL, BEI, and H2O2 revealed that the tested inactivants could completely and irreversibly inactivate rabies virus within 2, 12, and 4 hours, respectively while maintaining its viral immunogenicity. The potency of βPL, BEI, and H2O2 inactivated vaccines was higher than the World Health Organization acceptance limit and were in the order of 3.75, 4.21, and 3.64 IU/mL, respectively. Monitoring the humoral and cellular immunity elicited post-immunization using Staphylococcus aureus derived hyaluronic acid (HA) and bacillus Calmette-Guérin purified protein derivative (PPD) adjuvanted rabies vaccine candidates were carried out using enzyme-linked immunosorbent assay. Results: Results demonstrated that both adjuvants could progressively enhance the release of anti-rabies total immunoglobulin G as well as the pro-inflammatory mediators (interferon-gamma and interleukin-5) relative to time. However, a higher immune response was developed in the case of HA adjuvanted rabies vaccine compared to PPD adjuvanted one. The harmful consequences of the tested adjuvants were considered via investigating the histopathological changes in the tissues of the immunized rats using hematoxylin and eosin stain. Lower adverse effects were observed post-vaccination with HA and PPD adjuvanted vaccines compared to that detected following administration of the currently used alum as standard adjuvant. Conclusion: Our findings suggested that HA and PPD could serve as a promising platform for the development of newly adjuvanted rabies vaccines with elevated immune enhancing potentials and lower risk of health hazards.