Tunis University

About: Tunis University is a education organization based out in Tunis, Tunisia. It is known for research contribution in the topics: Population & Thin film. The organization has 11745 authors who have published 15400 publications receiving 154900 citations. The organization is also known as: University of Tunis & UT.

Multiple regression analysis of the sources of variation in orientation of two sympatric sandhoppers, Talitrus saltator and Talorchestia brito, from an exposed Mediterranean beach

Abstract: Two sympatric species from an exposed sandy beach in north-western Tunisia, the sandhoppers Talitrus saltator (Montagu) and Talorchestia brito Stebbing, were compared as regards orientation under natural conditions. Sets of experiments were carried out on the beach using two experimental arenas, one permitting the view of both the sky and landscape and the other of the sky only. Replicates were made at different hours of the day, in different days and period of the year and with various climatic conditions. Multiple regression models were fitted to the angular data obtained. These models allow an estimate of the trends of variation depending on a combination of factors. The simultaneous effects of environmental factors influencing orientation were quantified for each species. The sun was confirmed as the major orientation cue in these populations, but the concentration of directional choices was enhanced by the landscape vision. The climatic factors affected orientation in different ways depending on the time of day and year. When the two species were compared, Talitrus saltator showed a higher flexibility of response than Talorchestia brito under the same environmental conditions, supporting the hypothesis of a higher level of terrestrialization of the former species.

Production and characterization of bio-oil from the pyrolysis of waste frying oil.

Abstract: In this present work, the disposal of waste frying oil was explored. The experiment tests were performed under nitrogen (N2) atmosphere at 5 °C/min heating rate from the ambient temperature to 500 °C. In these operating conditions, the obtained pyrolitic liquid fraction was 76 wt% formed by 63.87 wt% of crude bio-oil and 12.13 wt% of aqueous fraction. The chemical characterization using FTIR, GC, and GC/MS has revealed that the bio-oil is a complex chemical mixture of linear saturated, unsaturated, and cyclic hydrocarbons and oxygenated compounds such as carboxylic acids, ketones, aldehydes, and alcohols. Moreover, the produced bio-oil can be considered as promising fuel with high calorific value (∼39 MJ/kg). However, the higher acidity (∼125 mg KOH/g sample) and viscosity (9.53 cSt at 40 °C) limit currently its direct use in engines. Therefore, although several promising results, further investigations are requested to improve the bio-oil quality in order to find an environmentally friendly issue to waste frying oil.

Molecular characterization of methicillin-resistant Panton-valentine leukocidin positive staphylococcus aureus clones disseminating in Tunisian hospitals and in the community.

Abstract: The spread of MRSA strains at hospitals as well as in the community are of great concern worldwide. We characterized the MRSA clones isolated at Tunisian hospitals and in the community by comparing them to those isolated in other countries. We characterized 69 MRSA strains isolated from two Tunisian university hospitals between the years 2004-2008. Twenty-two of 28 (79%) community-associated MRSA (CA-MRSA) strains and 21 of 41 (51%) healthcare-associated MRSA (HA-MRSA) strains were PVL-positive. The PVL-positive strains belonged to predicted founder group (FG) 80 in MLST and carried either type IVc SCCmec or nontypeable SCCmec that harbours the class B mec gene complex. In contrast, very diverse clones were identified in PVL-negative strains: three FGs (5, 15, and 22) for HA-MRSA strains and four FGs (5, 15, 45, and 80) for CA-MRSA strains; and these strains carried the SCCmec element of either type I, III, IVc or was nontypeable. The nucleotide sequencing of phi7401PVL lysogenized in a CA-MRSA strain JCSC7401, revealed that the phage was highly homologous to phiSA2mw, with nucleotide identities of more than 95%. Furthermore, all PVL positive strains were found to carry the same PVL phage, since these strains were positive in two PCR studies, identifying gene linkage between lukS and mtp (major tail protein) and the lysogeny region, both of which are in common with phi7401PVL and phiSa2mw. Our experiments suggest that FG80 S. aureus strains have changed to be more virulent by acquiring phi7401PVL, and to be resistant to β-lactams by acquiring SCCmec elements. These novel clones might have disseminated in the Tunisian community as well as at the Tunisian hospitals by taking over existing MRSA clones.