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This paper aims to numerically solve fully developed laminar flow in trapezoidal ducts with rounded corners which result following forming processes.

A two-dimensional model for a trapezoidal duct with rounded corners is developed and conservation of momentum equation is solved. The flow is assumed to be steady, fully developed, laminar, isothermal and incompressible. The key flow characteristics including the Poiseuille number and the incremental pressure drop have been computed and tabulated for a wide range of: sidewall angle (θ); the ratio of the height of the duct to its smaller base (α); and the ratio of the fillet radius of the duct to its smaller base (β).

The results show that Poiseuille number decreases, and all the other dimensionless numbers increase with increasing the radii of the fillets of the duct; these effects were found to amplify with decreasing duct heights or increasing sidewall angles. The maximum axial velocity was shown to increase with increasing the radii of the fillets of the duct. For normally used ducts in hydrogen fuel cells, the impact of rounded corners cannot be overlooked for very low channel heights or very high sidewall angles.

The data generated in this study are highly valuable for engineers interested in estimating pressure drops in rounded trapezoidal ducts; these ducts have been increasingly used in hydrogen fuel cells where flow channels are stamped on thin metallic sheets.

Fully developed laminar flow in trapezoidal ducts with four rounded corners has been solved for the first time, allowing for more accurate estimation of pressure drop.

The purpose of this paper is to evaluate the efficiency of commercial silica, silica fume-waste (SF) and modified silica fume-waste (mSF) as reinforcing filler in acrylonitrile-butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) through the mixing process of rubber. The composites were prepared using different loadings of silica fume and commercial silica in EPDM and NBR composites. Structural characterization of silica and SF was done using X-ray fluorescence and scanning electron microscopy (SEM). The surface of silica fume waste was modified using poly methyl methacrylate/butyl acrylate through emulsion polymerization to increase the interaction between silica and rubber, then consequently better dispersion in rubber matrix was obtained. The mSF waste was characterized using FT-IR spectra and transmission electron microscopy.

The investigated rubber mixes and vulcanizates were evaluated by measuring the curing characteristics, mechanical testing, thermogravimetric analysis and morphological studies (SEM). The mechanical properties of composites including tensile strength, elongation at break and modulus were estimated and analyzed.

The results revealed that the composites (NBR and EPDM) containing mSF as filler exhibited better rheological and mechanical properties compared to unmodified silica waste and commercial silica. The SEM analysis indicated that the mSF was homogeneously dispersed through the surface of NBR and EPDM composites. Also, results showed that (NBR and EPDM) composites exhibited remarkable improvements in tensile strength, elongation at break and hardness in the presence of mSF; they also showed an increase in the thermal stability. This means that the treatment of surface SF can improve its dispersion in rubber.

Silica cannot be applied in rubber matrix without surface modification because of their incompatibility; their dispersion is not good without surface modification.

The modified silica surface is considered as effective reinforcing filler which can replace other fillers because of its lower surface energy and enhanced intercalating behavior in rubber.

This study is just a start in establishing rubber projects with wide applications in the industry and providing a cheap local product while preserving the quality and that is the use of factory waste, which helps in protecting the environment from pollution.

mSF is cheap with relatively high purity, which make rubber/mSF composites appear as new grade of material that can be used in different media rather than rubber.

This paper aims to evaluate the antimicrobial and antioxidant activity of ethanol, methanol and aqueous extracts of the jujube fruit.

The fruit samples were harvested from Ziziphus lotus L. in three regions of Morocco: Aïn Chifae (Immouzer), Saiss (Fez) and Guercif. The fruit extracts were obtained by Soxhlet method using ethanol, methanol and water, and then a phytochemical screening was done for each extract. Total phenolic and total flavonoids contents were also determined. Afterward, the antimicrobial activity of the studied extracts was evaluated using the broth microdilution method. To estimate the total antioxidant effect of these extracts, the DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging and phosphomolybdate tests were performed.

Results showed that the highest content of polyphenols and flavonoids was found for ethanol and methanol extracts, while the lowest content was found in the aqueous extracts for all populations studied. Thus, results showed that the highest content of phenolic compounds was recorded in the population of Fez. Methanol extract of this population was the richest in polyphenols (30.36 mg/g) and in flavonoids (13.03 mg/g). The antimicrobial tests showed that Enterococcus faecalis and Pseudomonas aeruginosa were the most sensitive (6.25 mg/ml), compared to the other tested strains. Based on the minimal bactericidal concentrations/minimal fungicidal concentration or MFC/MIC ratio, it seems that ethanol extracts showed a bactericidal effect against Escherichia coli, Staphylococcus aureus and Bacillus subtillis, and a bacteriostatic effect against Enterococcus faecalis. On the other hand, the methanol extract showed bacteriostatic effect against Enterococcus faecalis and Pseudomonas aeruginosa. In addition, methanol extracts of Ziziphus lotus have significant antioxidant potent.

Methanol and ethanol extracts of Ziziphus lotus fruit have demonstrated strong antimicrobial effect. Moreover, the authors were able to show that the extract of Ziziphus lotus fruit has a very important antioxidant power.

Muslims as an ummah (community) held knowledge power for more than 500 years and dominated in the field of historiography, religious texts, medicine, astronomy, mathematics, sciences, literature, geography and travel and many other areas during AD 750‐950 in world history. But the present Muslim world is far behind in knowledge power than the rest of the world despite the fact that it holds vast sources of economic resources. How Muslim knowledge powers became great and how they declined is a question that confronts today's researchers. The purpose of this paper is to identify the factors responsible for the rise and fall of Muslims’ knowledge power and the scope for its restoration.

An in‐depth analysis was made based on the information from secondary sources.

In order to restore the flagging knowledge power, six factors have been identified and analyzed in the light of presenting the scope for initiative to power the knowledge economy in the Muslim world.

The paper shows that the concept of knowledge power not only identifies circumstances in which the Muslim world can restore knowledge economy well but also in which it should come up with a realistic action plan in the area of higher education and human resources development.

Highly committed, motivated and engaged employees assure organizational success and competitiveness. The study aims to examine the association between human resource development (HRD) practices and employee engagement with organizational commitment as a mediating variable.

Data were collected from 760 employees of 13 star-rated hotels comprising 5 (five-star) and 8 (four-star). The data supported the hypothesized relationships. Structural equation modeling was used to evaluate the proposed model and hypotheses. Construct validity and reliability were established through confirmatory factor analysis.

The results indicate that HRD practices and affective commitment are significantly associated. HRD practices and continuance commitment were shown to be non-significantly associated. HRD practices and normative commitment were shown to be non-significantly associated. Employee engagement and organizational commitment are significantly associated. The results further show that organizational commitment mediates the association between HRD practices and employee engagement.

The generalizability of the findings will be constrained due to the research's hotel industry focus and cross sectional data.

The study's findings will serve as valuable pointers for stakeholders and policymakers of the hotel industry in the adoption, design and implementation of proactive HRD interventions to keep highly engaged and committed employees for organizational competitiveness and sustainability.

By evidencing empirically that organizational commitment mediates the nexus between HRD practices and employee engagement, the study extends the literature.

This paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell.

A comprehensive three-dimensional polymer electrolyte membrane fuel cell model has been developed, and a set of conservation equations has been solved. The flow is assumed to be steady, fully developed, laminar and isothermal. The investigated cross sections are the commonly used square cross section, the increasingly used trapezoidal cross section and a novel hybrid configuration where the cross section is square at the inlet and trapezoidal at the outlet.

The results show that a slight gain is obtained when using the hybrid configuration and this is because of increased velocity, which improves the supply of the reactant gases to the catalyst layers (CLs) and removes heat and excess water more effectively compared to other configurations. Further, the reduction of the outlet height of the hybrid configuration leads to even better fuel cell performance and this is again because of increased velocity in the flow channel.

The data generated in this study will be highly valuable to engineers interested in studying the effect of fluid cross -sectional shape on fuel cell performance.

This study proposes a novel flow field with a variable cross section. This design can supply a higher amount of reactant gases to the CLs, dissipates heat and remove excess water more effectively.

This paper aims to synthesize new benzimidazole dyes aiming to study the solvent effects on their absorption in Ultraviolet-visible spectra.

Ureido/thioureido hydrazonamide benzimidazoles (U/THB) are prepared by condensation of N-aryl-1H-benzo[d]imidazole-2-carbohydrazonoyl bromides with ureido and/ or thioureido reagents. The target products are fully characterized for structural elucidation by means of their spectral and elemental methods. Solvatochromic behavior of U/THB dyes has been studied in different polar protic solvents at room temperature.

The absorption spectra distinguish two main bands at (350 nm–442 nm) and (308 nm–382 nm) referring to n-π* and π- π* transitions of the azo groups. Dimethyl formamide induces an extremely bathochromic transition comparing to the other protic solvents. The observed bathochromic shifts indicate strong interaction with solvents in the excited state. Most dyes show one absorbance in all solvents used, so they may exist in a single tautomeric form (hydrazo form).

In the present paper, the synthesis of U/THB dyes was achieved by a simple and convenient pathway. In addition, the variations in substituents attached to the chromophoric moiety could also be studied.

The new U/THB dyes are accountable for providing good knowledge about their solvation and spectral properties of an order acceptable for industrial utilization.

Synthesis of these new benzimidazole derivatives and study of their solvation and spectral properties provides good knowledge, which is very useful in many industrial applications (e.g. dye-sensitized solar cell, etc.).

The synthesized mono azo U/THB dyes are novel members in the benzimidazole family, where no details regarding the synthesis of such dyes are reported before in the literature. They are superior in terms of preparation, multiple applications and spectral properties.

Sustainable development is an attempt to achieve three competing aims: economic development, social justice and environmental conservation. Localising sustainable development in the Arabian city might require a framework that originates from its reality manifested in the region’s history, culture and religion. Ibn Khaldun’s model seems suitable for planning a sustainable city in the Arab world. The purpose of this paper is to discuss suitability of Ibn Khaldun’s writing to localising sustainable development in the Arabian cities.

The paper used a qualitative research methodology. The researcher investigated the writings of Ibn Khaldun and other scholars who studied his work to derive lessons for planning the sustainable Arab city.

Many of Ibn Khaldun’s concepts lost their accuracy, meanings and intentions in the course of translating his work. Ibn Khaldun’s writings can be the source from which scholars, planners and city administrators derive lessons to assure the sustainable development of human settlements, particularly in the Arab region. The writings of Ibn Khaldun are relevant to the Arab countries. His writings are sensitive to the realities of the Arab world, including geography, environment, history, religion and culture. His writings can support efforts for localising sustinable development in the Arabian cities.

Interrogating Ibn Khaldun’s writings can enable scholars, planners, architects and city administrators to elaborate and implement plans for the sustainable Arabian city. The findings of the paper assure that Ibn Khaldun’s analysis is suitable for addressing the urban ills of the contemporary Arabian metropolis as they were in his time.

This study refines theory of social capital by nesting it within a cultural context. More specifically, it aims at describing, explaining, and predicting the role of wasta, a social capital concept, as a moderator in the relationship between employees' ethical idealism and work engagement in Lebanon.

Based on a survey questionnaire translated from English into Arabic, 317 responses were collected from employees in Lebanon. Confirmatory factor analysis and hierarchical regression analysis were employed to test the hypothesized relationships among the examined variables.

Ethical idealism was found to be positively related to work engagement, and wasta was found to moderate the relationship between ethical idealism and work engagement. Work engagement levels of employees who displayed high levels of ethical idealism were less influenced by the negative effect of wasta than work engagement levels of employees who displayed low levels of ethical idealism.

Human resource managers, international negotiators, and global executives in Lebanon may use the findings of this study to update corporate human resources systems, such as employee recruitment and selection, handbooks, orientation, training programs, and performance appraisal, to better address employee attitudes toward the practice of wasta.

The study adds ethical idealism as an antecedent of work engagement, demonstrating the significant impact that wasta, with its positive and negative characteristics, has on the engagement of employees from the Arab world.

This study provides an overview of the application of sentiment analysis (SA) in exploring social movements (SMs). It also compares different models for a SA task of Algerian Arabic tweets related to early days of the Algerian SM, called Hirak.

Related tweets were retrieved using relevant hashtags followed by multiple data cleaning procedures. Foundational machine learning methods such as Naive Bayes, Support Vector Machine, Logistic Regression (LR) and Decision Tree were implemented. For each classifier, two feature extraction techniques were used and compared, namely Bag of Words and Term Frequency–Inverse Document Frequency. Moreover, three fine-tuned pretrained transformers AraBERT and DziriBERT and the multilingual transformer XLM-R were used for the comparison.

The findings of this paper emphasize the vital role social media played during the Hirak. Results revealed that most individuals had a positive attitude toward the Hirak. Moreover, the presented experiments provided important insights into the possible use of both basic machine learning and transfer learning models to analyze SA of Algerian text datasets. When comparing machine learning models with transformers in terms of accuracy, precision, recall and F1-score, the results are fairly similar, with LR outperforming all models with a 68 per cent accuracy rate.

At the time of writing, the Algerian SM was not thoroughly investigated or discussed in the Computer Science literature. This analysis makes a limited but unique contribution to understanding the Algerian Hirak using artificial intelligence. This study proposes what it considers to be a unique basis for comprehending this event with the goal of generating a foundation for future studies by comparing different SA techniques on a low-resource language.