Study the Nature and the Effects of the Impurities of Phosphate Rock in the Plants of Production of Phosphoric Acid

Phosphate rocks from different deposits vary widely in composition, and these variations have important effects in phosphoric acid production. All phosphate rocks contain many impurities. Knowledge of the nature and contents of the various elements in the phosphate is required in the manufacturing process of phosphoric acid. All these chemical characteristics can help the operator to foresee its objectives under the operating conditions and the cost of production in the manufacturing process of phosphoric acid.Two Tunisian natural phosphates coming from two different deposits were selected. We propose in this work studying the effects of the impurities that depending on their concentration can affect decisively the behavior of these ores in the process of production of phosphoric acid. Study the chemical composition of these ores is carried out according to standard analytical methods used for raw phosphates.The results obtained show a slight difference in chemical properties between the two types of sedimentary phosphates and their aptitude to be used in the plants of production of phosphoric acid.Â

Solubility Study and purification Of Industrial triple superphosphate in aqueous solution

Triple Superphosphate (TSP) is a chemical fertilizer, acknowledged by its important content of phosphorus, necessary element for plants. It’s obtained by adding phosphoric acid to phosphate ore, consisting of calcium phosphate containing many impurities. TSP was dissolved at different temperatures and in various amounts of water, filtered to remove insoluble compounds. Then the ionic conductivity was monitored for each solution as a function of the added amount of TSP. Aqueous solutions were evaporated to dryness and analyzed the P2O5. The starting materials and final products were analyzed by several methods (XRD, IR, NMR, SEM) confirming that after dissolution the product was purified

Retention of Organic Matter Contained in Industrial Phosphoric Acid Solution by Raw Tunisian Clays: Kinetic Equilibrium Study

Purification of industrial phosphoric acid (H 3 PO 4 ) is considered a major problem and several methods have been evaluated. In this study, two different types of clay, raw bentonite clay (RBC) and raw grey clay (RGC), were used for removal of SOM contained in H 3 PO 4 at low pH. The used samples were characterized by X-ray diffraction, chemical analysis, and specific surface area and MET was also realized. The ability of clay samples to remove S.O.M from aqueous solutions of industrial phosphoric acid has been studied at different operating conditions: temperature, agitation speed, contacting time, and so on. The results indicated that adsorption is an exothermic process for lead S.O.M removal. The equilibrium adsorption data were analysed using the Langmuir and Freundlich isotherms. The results showed that the equilibrium adsorption capacities for the two adsorbents followed best the Langmuir model. Thermodynamic parameters showed that the adsorption process was spontaneous and exothermic

La question du rapport au corps dans la formation en STAPS : Cas de deux enseignants universitaires tunisiens

Comment le corps de l’enseignant universitaire expérimenté se déploie-t-il en formation pratique STAPS ? Cette étude comparative de l’effet du rapport au corps de deux enseignants universitaires expérimentés sur leurs pratiques enseignantes se base sur une double filiation théorique : didactique et clinique d’inspiration psychanalytique (Terrisse & Carnus, 2009 ; Carnus & Terrisse, 2013). Elle constitue le prolongement des travaux de l’EDiC sur la didactique universitaire (Sghaier, Ben Jomâa, Mami, Kpazaï, & Bouassida, 2019 ; Ben Jomâa, Abdelkefi, Chili, Majdoub, & Kpazaï, 2018) et se réfère ainsi au cadre théorique de la didactique clinique universitaire à perspective de formation (Romainville, 2002 ; Altet, 1994 ; Perrenoud, 1994). Le primat accordé à l’analyse de la place du rapport « différentiel » au corps dans l’enseignement supérieur, à travers le prisme de l’expérience professionnelle et au regard du genre (Ben Jomâa, 2019) vise à étudier les articulations entre rapport au corps, genre et action didactique. Cette prise en compte a priori et a posteriori de la pratique enseignante s’organise à travers deux études de cas rapprochés, dont nous avons l’intention d’examiner et d’en comparer notamment le rapport au corps (féminin vs masculin) et son rôle dans les choix didactiques, quant à l’usage de la distance « didactique », des formes ostensives et des formes de proxémie sous un angle clinique. Cette recherche se veut descriptive et compréhensive. Elle se focalise sur l’analyse des ressorts de l’acte d’enseignement au supérieur à travers une épistémologie pratique privée, un déjà-là singulier et des postures professorales différenciées. Les résultats de la présente recherche ont permis d'identifier un rapport « différentiel au corps » qui se déploie. L'enseignant masculin a un rapport techniciste au corps, tandis que l'enseignante féminin a un rapport régulateur au corps. Ce rapport « différentiel au corps » est révélateur d’un rapport au savoir singulier, propre à l'histoire de chaque enseignant. How can the university teacher’s body be deployed in the STAPS initial training? This comparative study aims to examine the effect of the link to body of two experimented university teachers on their teaching practice. It is based on a double theoretical filiation: didactical and clinical from a psychoanalytical inspiration (Terrisse & Carnus, 2009 ; Carnus & Terrisse, 2013). This study follows the EDiC works on the higher education didactics (Sghaier, Ben Jomâa, Mami, Kpazaï, & Bouassida, 2019 ; Ben Jomâa, Abdelkefi, Chili, Majdoub, & Kpazaï, 2018) and refers to its conceptual framework from a training perspective (Romainville, 2002 ; Altet, 1994 ; Perrenoud, 1994). A primacy is granted to the analysis of the ‘differential’ link to body of the teacher through the professional experience and the gender (Ben Jomâa, 2019). This aims to study the linkage between the link to body, gender, and the didactics action. We take into account the teaching practice a priori and a posteriori through two reconciled cases-study which we intend to examine and to compare their link to body (feminine vs masculine). This comparison plan to examine the role of the didactic choices regarding the use of didactic distance, ostensive and proxemics forms. This study is mainly descriptive and comprehensive. It focuses on the analysis of the motives of the teaching act in higher education through a private practical epistemology, a singular ‘already-there’ and differentiated professorial postures. The results of this research have enabled us to identify a "differential to the body" relationship that deploys. The male teacher has a technical relationship to the body, while the female teacher has a regulatory relationship to the body. This "differential to the body" report is indicative of a relationship with singular knowledge, specific to the history of each teacher

The Influence of Maturity Status on Dynamic Balance Following 6 Weeks of Eccentric Hamstring Training in Youth Male Handball Players

Information about when to apply an appropriate eccentric hamstring strength training stimulus during long-term athlete development is essential for effective programming and improving balance performance. This study examined the effects of six-week eccentric hamstring training on dynamic balance performance in youth handball players of different maturity statuses (pre- or post-peak height velocity (PHV)). A randomized controlled design with 45 young male handball players (14.6 ± 0.3 years) from a local national handball club were randomly allocated to a 6 week, twice weekly eccentric hamstring training in two experimental groups: a pre-PHV (maturation offset: −2.13 ± 0.63, n = 10) and post-PHV (maturation offset: 0.79 ± 0.34, n = 12) group and two control groups: maturation offset: −2.09 ± 0.61, n = 10 and maturation offset: 0.55 ± 0.67, n = 13. Dynamic balance performance was evaluated by using the composite score during the lower quarter Y-balance test from pre- and post-intervention. A significant effect on balance scores was found from pre to post (F = 11.4; p = 0.002; η(2)(p) = 0.22), intervention (F = 5.4; p = 0.025; η(2)(p) = 0.12), and maturation (F = 369; p < 0.001; η(2)(p) = 0.9), but no significant interaction effects were found (F ≥ 3.3; p ≥ 0.077; η(2)(p) ≤ 0.07). Post hoc analysis revealed that the post-PHV group had a higher score than the pre-PHV group. Furthermore, that dynamic balance increased in the post-PHV group after intervention much more in the control post-PHV group. It was concluded that somatic maturation influences dynamic balance performance and that eccentric hamstring training results in greater improvement in balance performance in young male handball players for the post-pubertal group

Time interval moderates the relationship between psyching-up and actual sprint performance

This study attempted to test whether the strongest effect of psyching-up (PU) strategy on actual sprint performance can be observed when the strategy is used immediately (or almost) before performance compared with when there is a delay between PU and performance. To do so, 16 male sprinters (age, 20.6 ± 1.3 years; body mass, 77.5 ± 7.1 kg; height, 180.8 ± 5.6 cm) were enrolled in a counterbalanced experimental design in which participants were randomly assigned to 10 sessions (2 [Experimental Condition: imagery vs. distraction] × 5 [Time Intervals: no interval, 1 minute, 2 minutes, 3 minutes, and 5 minutes]). Before performing the experimental tasks, participants rated: (a) the Hooper index, (b) their degree of self-confidence, and (c) after the completion of the experimental test; they rated their perceived effort. Findings showed that the imagery significantly improved sprint performance. Specifically, the imagery enhanced performance on the phase of acceleration (0-10 m) and on the overall sprint (0-30 m) when used immediately before performance and at 1- and 2-minute intervals but not for 3- and 5-minute intervals. These findings support the hypothesis that the potential effect of the PU strategy on performance vanishes over time. The pre-experimental task Hooper and self-efficacy indexes did not change across the 10 experimental sessions, reinforcing the view that the observed performance changes were directly caused by the experimental manipulation and not through any altered status of the athletes (self-efficacy, fatigue/recovery, and stress). The potential mechanisms underlying such a process and practical applications are discussed

Acinetobacter baumannii ventilator-associated pneumonia: epidemiology, clinical characteristics, and prognosis factors

SummaryObjectiveThe aim of this study was to describe the epidemiological characteristics of Acinetobacter baumannii ventilator-associated pneumonia (VAP) and to identify factors predictive of a poor outcome.MethodsA retrospective study was conducted over 16 months in a Tunisian intensive care unit (ICU). All adult patients with A. baumannii VAP were included.ResultsNinety-two patients were included in they study; 41 (44.6%) were admitted because of multiple trauma. The mean age of the patients was 44.5±19.5 years. All patients needed mechanical ventilation on admission. The mean SAPS II score was 39±15. The mean delay before VAP onset was 8.1±4.7 days. On VAP onset, 57 patients (62%) developed septic shock. Only 14.2% of isolated strains were susceptible to imipenem; none were resistant to colistin. The mean duration of mechanical ventilation was 20±11 days. The mean duration of ICU stay was 24.3±18.7 days. ICU mortality was 60.9%. In the multivariate analysis, factors predictive of a poor outcome were previously known hypertension (odds ratio 5.8, 95% confidence interval 1.4–24.9; p=0.018) and VAP-related septic shock (odds ratio 8.5, 95% confidence interval 3–23.7; p<0.001).ConclusionA. baumannii VAP is associated with a high mortality. Hemodynamic impairment is predictive of a poor outcome

Change-of-direction performance in elite soccer players:Preliminary analysis according to their playing positions

International audienceOur objective was to examine the relationship between change of direction (CoD) performance, with (CoDb), and without the ball (CoDwb), and selected measures of physical fitness (jump performance, speed, balance) in elite soccer players, according to players’ positions. Forty elite male soccer players performed the change-of-direction and acceleration test (CODAT) with (CODATb), and without the ball (CODATwb), 5- and 20-m sprint tests, the 5-jump test (5JT), and the Y-balance test (YBT). Analyses of the whole sample showed significant correlations between all CODAT measures (CODATwb and CODATb, respectively) and sprint 5-m (r = 0.72, p &lt; 0.001; r = 0.52, p &lt; 0.01), sprint 20-m (r = 0.54, p &lt; 0.03; r = 0.45, p &lt; 0.05), jump (r = -0.62, p &lt; 0.01; r = -0.64, p &lt; 0.01) and balance (r = -0.50, p &lt; 0.01; r = -0.83, p &lt; 0.001) performances. Correlations were significantly different between player positions (defender, midfielder and striker). When examining the entire sample, the single best predictor of CODATwb was performance in the 5-m test with an explained variance of 52% (p &lt; 0.001). For CODATb, the Y-balance performance explained 68% of the variance of performance (p &lt; 0.001). In conclusion, soccer coaches and fitness trainers are advised to improve players’ CoD using neuromuscular training that mimic crucial match actions. Meanwhile, CoD testing and training should be designed in line with the demands of playing position

Change-of-Direction Performance in Elite Soccer Players: Preliminary Analysis According to Their Playing Positions

[EN] Our objective was to examine the relationship between change of direction (CoD) performance, with (CoDb), and without the ball (CoDwb), and selected measures of physical fitness (jump performance, speed, balance) in elite soccer players, according to players’ positions. Forty elite male soccer players performed the change-of-direction and acceleration test (CODAT) with (CODATb), and without the ball (CODATwb), 5- and 20-m sprint tests, the 5-jump test (5JT), and the Y-balance test (YBT). Analyses of the whole sample showed significant correlations between all CODAT measures (CODATwb and CODATb, respectively) and sprint 5-m ( r = 0.72 , p < 0.001 ; r = 0.52 , p < 0.01 ), sprint 20-m (r = 0.54, p < 0.03; r = 0.45, p < 0.05), jump (r = −0.62 , p < 0.01 ; r = −0.64 , p < 0.01 ) and balance (r = −0.50, p < 0.01; r = −0.83, p < 0.001) performances. Correlations were significantly different between player positions (defender, midfielder and striker). When examining the entire sample, the single best predictor of CODATwb was performance in the 5-m test with an explained variance of 52% (p < 0.001). For CODATb, the Y-balance performance explained 68% of the variance of performance (p < 0.001). In conclusion, soccer coaches and fitness trainers are advised to improve players’ CoD using neuromuscular training that mimic crucial match actions. Meanwhile, CoD testing and training should be designed in line with the demands of playing positio