Mohamed Frikha

Solvent free synthesis of 1,3-diaryl-2-propenones catalyzed by commercial acid-clays under ultrasound irradiation

This paper presents a novel solvent free method of synthesis of trans-chalcones. The method was based on ultrasound irradiation of the reagents (aryl methyl ketones and aryl aldehydes) in presence of commercial acid-montmorillonites as catalysts. The trans-chalcones were synthesized in high yields (85-95%) and excellent selectivity in a short reaction time.

A Semantic Social Recommender System Using Ontologies Based Approach For Tunisian Tourism

Tunisia is well placed in terms of medical tourism and has highly qualified and specialized medical and surgical teams. Integrating social networks in Tunisian medical tourism recommender systems can result in much more accurate recommendations. That is to say, information, interests, and recommendations retrieved from social networks can improve the prediction accuracy. This paper aims to improve traditional recommender systems by incorporating information in social network; including user preferences and influences from social friends. Accordingly, a user interest ontology is developed to make personalized recommendations out of such information. In this paper, we present a semantic social recommender system employing a user interest ontology and a Tunisian Medical Tourism ontology. Our system can improve the quality of recommendation for Tunisian tourism domain. Finally, our social recommendation algorithm is implemented in order to be used in a Tunisia tourism Website to assist users interested in visiting Tunisia for medical purposes.

Green condensation reaction of aromatic aldehydes with active methylene compounds catalyzed by anion-exchange resin under ultrasound irradiation.

To realize a practical and green chemistry, two important challenges need to be addressed, namely the effective process for the activation of reaction and efficient, eco-friendly and robust chemical methods for the reaction conversion to target products via highly selective catalytic and reactions. Ultrasonic energy promotes the conversion process through its special cavitational effects. Combined with anion-exchange resin as a heterogeneous, reusable and efficient catalyst, Ultrasonic energy enhances the Knoevenagel condensation and leads to reduced reaction time at lower reaction temperature with less amounts of solvent and catalyst.

Toward a User Interest Ontology to Improve Social Network-Based Recommender System

This paper aims to improve traditional recommender systems by incorporating information in social networks, including user preferences and influence from social friends. A user interest ontology is developed to make personalized recommendations out of such information. In this paper, we present a preliminary work that sheds light on the role of social networks as sources for the development of recommendation systems. The need for user interest ontology in recommender systems and its importance as a reference to find similar items in social network is also emphasized. Finally, we describe and account for the role of user interest model based on user interest ontology to deal with the lack of semantic information in personalized recommendation system.

Warm-up durations and time-of-day impacts on rate of perceived exertion after short-term maximal performance

The purpose of this investigation was to assess the effects of different active warm-up (AWU) durations on the diurnal variations of power output during the Wingate test and the rate of perceived exertion (RPE). Eleven male handball players, volunteered to take part in this study, underwent six Wingate tests at 08:00 and 18:00 h after 5 (AWU5), 15 (AWU15), or 20 min (AWU20) of AWU. All the warm-up protocols consisted of pedaling at a constant pace of 60 rpm against 50% of the maximal aerobic power. RPE scores were recorded after the AWU and Wingate test. During the Wingate test, the peak (PP), the mean power (MP), and the fatigue index were measured. The RPE values were not affected by the time-of-day after both AWU and the Wingate test. The PP and MP during the Wingate test were: (i) higher in the evening in comparison with the morning (p < 0.001 and p < 0.01, respectively). (ii) Better PP and MP were recorded after AWU15 than after AWU5 and AWU20 at 08:00 h. Time-of-day affects the Wingate test performance, but not the RPE scores. Moreover, before morning competition, subjects could be advised to increase morning AWU, but not longer than 15 min.

Time-of-day effect on dart-throwing performance and the perception of the difficulty of the task in 9–10 year-old boys

The aim of this study was to examine the time-of-day effects on dart-throwing performance (at two distances from the dartboard) and the perception of the difficulty of the task in 9–10 year-old boys. In a randomized order, 12 healthy boys (age = 9.8 ± 0.5 years, height = 144 ± 6.2 cm, and body-mass = 32.7 ± 3.4 kg) performed two test sessions, in the morning at 07:00 h and in the evening at 17:00 h. During each test session, performance during the dart-throwing test, oral temperature, and perceived difficulty (PD) of the task were recorded. Performance at throwing darts was scored by three methods: mean distance of the dart from the bulls-eye, number of times the target was missed (number of zeros), and variability of the scores from the darts thrown. Our results revealed that performance at throwing darts was significantly better in the afternoon than the morning, with lowest mean distance of the dart from the bulls-eye around the time of maximal values of oral temperature (p < 0.001). Also, the number of zeros and variability in the scores of the darts thrown at both short and long distances decreased at 17:00 h in comparison with 07:00 h (p < 0.05), again indicating a better performance in the afternoon. The PD of the task decreased significantly with time of day, with greater values at 07:00 h in comparison with 17:00 h (p < 0.05). Moreover, the PD of the task was higher with long than short distances (p < 0.001). In conclusion, this study demonstrates that psychomotor performance was better in the afternoon than the morning.

Failure Factors in Tunisian Micro-enterprises: Introspection through Cognitive Mapping

Abstract This paper aims to identify the key factors of entrepreneurial failure in Sfax, a Tunisian region known for its entrepreneurial culture, using a sample of 150 micro-enterprises operating in different sectors of the economy. To study this particular phenomenon, the authors used the cognitive approach and the structural analysis, regarded as a tool for structuring ideas and for schematizing the mental image of micro-entrepreneurs. The results show that the weak engagement and the insufficient wealth of human, financial and social capital of microentrepreneurs represented the main potential barriers that reduced the success of their micro-enterprises. This study also emphasizes the importance of the attributes of human and social resources (e.g., education, experience, knowledge and skills, social networks, and family) as critical resources for successful individual businesses.

Banks and economic growth in developing countries: What about Islamic banks?

Abstract Islamic banks (IBs) have a significant role in the growth of gross domestic product of the developing countries. The Islamic participatory schemes integrate the assets of lenders and borrowers. They allow enable IBs to lend on a longer term basis to create projects with higher risk-return profiles and, thus, to support economic growth. Our investigation examines the contribution of Islamic finance in economic growth. Using a panel data-set, we compare between IBs and conventional banks in their adding to economic growth. We studied a sample of 120 banks between 2005 and 2012. By means of three ordinary least-square regressions, our empirical investigation reveals that the development of non-usurious banks supports economic growth. Moreover, the cooperation between the two financing modes improves economic growth. The integration of this new funding never neglected the role of the conventional method of financing. The practice of IBs is also away from their theoretical mode in terms of participation results.

Designing a User Interest Ontology-Driven Social Recommender System: Application for Tunisian Tourism

The tremendous growth of online social networks all over the world has created a new place and means of social interaction and communication among people. This paper aims to improve traditional recommender systems by incorporating information in social networks, including user preferences and influences from social friends. A user interest ontology is developed to make personalized recommendations out of such information. In this paper, we present a social recommender system employing a user interest ontology. Our system can improve the quality of recommendation for Tunisian tourism domain. Finally, our social recommendation algorithm will be implemented in order to be used in a Tunisia tourism Website to assist users interested in visiting Tunisian places.

How small business fail in Tunisia

This paper aim to draw an average cognitive map in order to explain the failure factors of Tunisian small business. The method adopted in the study of this phenomenon is the cognitive approach. Our study extends entrepreneurship literature and previous studies by proposing a new approach to building an average cognitive map for the explanation of small businesses failure.