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.

Motivation and learning - The role of interest in construction of representation of text and long-term retention: Inter- and intraindividual analyses

Abstract: The present work examined the influence of topic interest on the strength of different components of text representation and long-term retention according to the model of text processing by van Dijk and Kintsch (1983). A Series of relevant personality characteristics were assessed to control for alternative explanations of interest effect. A total of 286 8th, 9th, and 10th grade students was assigned to either a high topic interest or a low topic interest group. The participants had to read tow different texts (two weeks). Immediately afterwards, various process variables were assessed: Finally, participants weren given a recognition and verification tests, designed to assess the strength of the verbatim, propositional, and situational text representation. One Week after reading, students completed a recall rneasure: The interindividual finding with respect to the components of the representation of text revealed that the verbatim and the prepositional representation were not very predictable. The intraindividual analyses were more successful. The results were more consistent and interpretable with respect to the recall of text. It was shown quite clearly that the effects of interest are not only short-term. Most importantly, it could be shown that topic interest is related to text recall independently of other significant predictors.

Identification of potent nanobodies to neutralize the most poisonous polypeptide from scorpion venom.

Abstract: Scorpion venom, containing highly toxic, small polypeptides that diffuse rapidly within the patient, causes serious medical problems. Nanobodies, single-domain antigen-binding fragments derived from dromedary heavy-chain antibodies, have a size that closely matches that of scorpion toxins. Therefore these nanobodies might be developed into potent immunotherapeutics to treat scorpion envenoming. Multiple nanobodies of sub-nanomolar affinity to AahII, the most toxic polypeptide within the Androctonus australis hector venom, were isolated from a dromedary immunized with AahII. These nanobodies neutralize the lethal effect of AahII to various extents without clear correlation with the kinetic rate constants kon or koff, or the equilibrium dissociation constant, KD. One particular nanobody, referred to as NbAahII10, which targets a unique epitope on AahII, neutralizes 7 LD50 of this toxin in mice, corresponding to a neutralizing capacity of approx. 37000 LD50 of AahII/mg of nanobody. Such high neutralizing potency has never been reached before by any other monoclonal antibody fragment.

DFT study of the reaction of quercetin with ·O2- and ·OH radicals

Abstract: Free radical oxygen species act on biological constituents like lipid, cell membrane and deoxyribonucleic acids by changing their biological functions These effects are associated with the appearance of anomalies like allergies, cancer, viral infections, inflammations, etc Antioxidants like flavonoids are abundant in plants and are good scavengers of reactive oxygen species (ROS) Their antioxidant activities are measured through hydrogen atom transfer or charge transfer These mechanisms depend on the structure of the flavonoid or the nature of the free radical In this paper, we study the interaction of one of the most reactive flavonoid quercetin with two ROS: hydroxyl radical ( · OH ) and superoxide radical ( · O 2 - ) using B3LYP/6-31++G*level of theory Correlations between structural changes and antioxidant activity are shown The potential energy surfaces (PES) are calculated in both cases and indicate a transition state (TS) only for the reaction of quercetin with the hydroxyl radical This transition state is only localized at the B3LYP/3-21G level of theory This comparison between the reactants, the TS and the products of the reaction with the · OH radical indicate the nature of the transfer As far as the reaction of quercetin with the superoxide anion radical is concerned, the PES shows the inexistence of one transition state The nature of the charge transfer is thus determined using the natural bond orbital (NBO) and the singlet occupied molecular orbital (SOMO) analysis