Experimental study of solar energy potential in the gulf of Tunis, Tunisia

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.This work carries out the availability of the global solar radiation over the site of Borj-Cedria in the gulf of Tunis (36°43’04” N latitude and 10°25’41” E longitude), Tunisia. Global solar radiation variability was assessed on hourly, daily, monthly and seasonal scales. Solar potential in the gulf of Tunis was evaluated using the solar radiation data collected by the meteorological NRG weather station installed in the Centre of Research and Technologies of Energy (CRTEn) in the Borj- Cedria area. The collected measurements during the last three years (2008, 2009 and 2010) were based on 10 minute time step. These data have allowed us to evaluate the global solar flux, the sun duration, the yearly and the seasonal frequency distribution of the global solar radiation. Moreover, a conventional model has been used to estimate the hourly solar radiation on a horizontal plane and it has been validated by experimental measurements in specific days. The results show that the global solar radiation predicted by the conventional model has a good agreement with the experimental data during the clear sky conditions with a relative error percentage of 4.1%. However, the limitation of the conventional model appears under the cloudy sky weather which is proved by the highest value of relative error percentage reaching 14.26% occurred during the autumnal equinox day.dc201

Modeling and investigation of the wind resource in the gulf of Tunis, Tunisia

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The development of wind energy conversion systems becomes one of the most important aims of any developing countries such as Tunisia. This is due to the reduction in wind turbine costs, and in fossil fuel atmospheric pollution. The evaluation of wind power potential is very necessary to estimate wind resource and therefore conduct the suitable decisions for the wind power generation projects, technical and economical feasibility researches. The presented work in this paper was to investigate the potential of wind resource in the Gulf of Tunis in Tunisia. The hourly mean wind speed and wind direction with a 10-min time step provided by the NRG weather station were used to analyze the wind speed characteristics and the wind power potential. Weibull parameters are estimated based on the most frequently used methods which their accuracy was compared on different goodness of fit tests. Those wind characteristics are required to give wind project users the picture of wind potential in the Gulf of Tunis.dc201

Population Structure of Pseudomonas aeruginosa from Five Mediterranean Countries: Evidence for Frequent Recombination and Epidemic Occurrence of CC235

Several studies in recent years have provided evidence that Pseudomonas aeruginosa has a non-clonal population structure punctuated by highly successful epidemic clones or clonal complexes. The role of recombination in the diversification of P. aeruginosa clones has been suggested, but not yet demonstrated using multi-locus sequence typing (MLST). Isolates of P. aeruginosa from five Mediterranean countries (n = 141) were subjected to pulsed-field gel electrophoresis (PFGE), serotyping and PCR targeting the virulence genes exoS and exoU. The occurrence of multi-resistance (≥3 antipseudomonal drugs) was analyzed with disk diffusion according to EUCAST. MLST was performed on a subset of strains (n = 110) most of them had a distinct PFGE variant. MLST data were analyzed with Bionumerics 6.0, using minimal spanning tree (MST) as well as eBURST. Measurement of clonality was assessed by the standardized index of association (IAS). Evidence of recombination was estimated by ClonalFrame as well as SplitsTree4.0. The MST analysis connected 70 sequence types, among which ST235 was by far the most common. ST235 was very frequently associated with the O11 serotype, and frequently displayed multi-resistance and the virulence genotype exoS−/exoU+. ClonalFrame linked several groups previously identified by eBURST and MST, and provided insight to the evolutionary events occurring in the population; the recombination/mutation ratio was found to be 8.4. A Neighbor-Net analysis based on the concatenated sequences revealed a complex network, providing evidence of frequent recombination. The index of association when all the strains were considered indicated a freely recombining population. P. aeruginosa isolates from the Mediterranean countries display an epidemic population structure, particularly dominated by ST235-O11, which has earlier also been coupled to the spread of ß-lactamases in many countries

Variation of amino acids in Prunus persica cultivars leaves with regard to leaf age

The central role of amino acids in cellular and plant physiology is of current interest. Information related to the implication of amino acids during leaf age is still scarce. This study examined changes in the profile of amino acids extracted from leaves of five peach cultivars (‘Early Maycrest’, ‘Sweet Cap’, ‘O'Henry’, ‘Flordastar’, and ‘Rubirich’) grown in the region of Sidi Bouzid, central-western Tunisia with respect to leaf age. Seventeen amino acids, aspartic acid (Asp), serine (Ser), glycine (Gly), proline (Pro), tyrosine (Tyr), valine (Val), methionine (Met), cysteine (Cys), tryptophan (Trp), leucine (Leu), phenylalanine (Phe), isoleucine (Ile), lysine (Lys), glutamic acid (Glu), arginine (Arg), alanine (Ala), and histidine (His) were quantified. Significant variations were observed for Asp, Glu, Ser, Gly, Ala + Arg, Pro, Val, Ile + Trp, and Lys in relation to the leaf age. On average, young leaves (106.48–142.18 mg g−1 DW) contained higher amounts of most amino acids than mature leaves (97.33–110.27 mg g−1 DW). Approximately identical contents of amino acids were found in the different cultivars. In conclusion, P. persica leaves are a very rich source of amino acids (about 10% DW), and therefore deserves further investigation for their potential application in the nutraceutical, food, feed, and pharmaceutical industries

A greenhouse investigation of responses to different water stress regimes of Laurus nobilis trees from two climatic regions

Plants from two populations of Laurus nobilis (Tunisia issued from a semi-arid inland site and Algeria originating from a coastal sub-humid area) were exposed during three months under similar controlled conditions to two stress intensities of permanent stress (60% (S1) and 20% (S2) of Held capacity) or to cyclic water stress, plants being re-watered when the soil moisture dropped to 60% (S11) or 20% (S22) of field capacity. One-year old plants displayed contrasting physiological strategies to cope with water stress. Algeria exhibited a higher decrease in osmotic potential (psi s) in relation to stress-induced proline accumulation. Glycinebetaine accumulated in response to drought in response to permanent stress (Algeria) or cyclic stress (Tunisia). The two populations had similar net photosynthesis (A) but Algeria exhibited higher water use efficiency (WUE) than Tunisia. A drought-induced increase in the apoplastic water content (AWC) was noticed in response to mild stress intensities (S1 and S11) in Tunisia and in response to higher stress intensities (S2 and S22) in Algeria in relation to a stress-induced accumulation of pectin and proportion of arabinose within the pectic fraction. Bulk modulus of elasticity (E) increased in Tunisia in response to permanent drought and in Algeria in response to cyclic stress, as a result of a stress-induced increase in cellulose (Algeria) or hemicellulose (Tunisia). It is concluded that water stress tolerance could be achieved by both osmotic and elastic adjustment in the coastal population which did not exhibit a prodigal water use comparatively to the inland population. Differences between populations are strongly influenced by the kinetics of water stress application. (C) 2009 Published by Elsevier Ltd

Physiological responses and fruit quality of four peach cultivars under sustained and cyclic deficit irrigation in center-west of Tunisia

In arid and semi-arid regions, the research and application of new irrigation techniques that economize water without altering tree performance and fruit quality is a challenge. The aim of this study was to investigate the effect of two different deficit irrigation strategies on tree physiology and fruit quality of four Prunus persica cultivars: two early-ripening cultivars (Flordastar and Early Maycrest), a mid-season cultivar (Rubirich), and a late-ripening cultivar (O'Henry). During two consecutive seasons (2016 and 2017), three different irrigation treatments were established: i) Full Irrigation (FI; 100% ET c ), ii) Sustained Deficit Irrigation (SDI; 50% ET c ) and iii) Cyclic Deficit Irrigation (CDI; trees irrigated at 100% field capacity whenever the soil moisture dropped to 50% field capacity). Tree water status, gas exchange, yield, fruit pomology and the concentrations of the main sugars and organic acids were determined. Deficit irrigation decreased net photosynthesis rate, stomatal conductance and transpiration rate while it improved instantaneous water use efficiency (WUEins). In O'Henry cultivar, WUEins increased from 3.21 μ mol mmol –1 in FI to 7.04 μmol mmol –1 in CDI during harvest. Deficit irrigation significantly reduced shoot growth in the four cultivars. Furthermore, SDI decreased the yield significantly (from 41 to 26.3 kg in O'Henry cultivar during 2016), fruit size and weight while CDI increased soluble solids and sugar contents and decreased titratable acidity. The total sugar content increased significantly under deficit irrigation in all cultivars studied. In conclusion, CDI seems to be the best strategy in semi-arid regions, since it can save water and improve fruit quality parameters

Diagnostic challenge in a Tunisian patient with Familial Mediterranean Fever, sacroiliitis and coxitis

AbstractIntroductionFamilial Mediterranean Fever (FMF) is a hereditary auto inflammatory disease. The most common joint attack is an acute large joint monoarthritis most often affecting the knee or hip and lasting for several days. Rarely, a more protracted arthritis may occur.Case reportHerein, we describe a 47-year-old man with FMF in whom a few years elapsed before a definitive diagnosis could be made. The patient presented, since the age of 25, with a history of recurrent episodes of fever, abdominal pain, bloody diarrhea and intermittent attacks of acute bi-arthritis of hips. At the age of 40, he was referred under the suspicion of Spondylarthritis (SpA); in view of an inflammatory back pain, talalgia and bilateral coxitis. The result of blood tests suggested the presence of a high level of inflammation without leukocytosis. Human leukocyte antigen (HLA-B27) was negative. X-ray and computerized tomography of the pelvis showed an overall bilateral joint space narrowing of the hips and grade 3 bilateral sacroiliitis. During the hospitalization, he developed an acute episode of fever, abdominal pain and muscle contracture, spontaneously resolved in 12h. We suspected FMF based on the clinical course and family history, as one of his brothers had suffered similar abdominal crises since childhood. Molecular analysis for FMF was done, and demonstrated a homozygote mutation of M649V. A definitive diagnosis of FMF was then made. Oral administration of colchicine was followed by a remission.ConclusionClinicians should consider FMF with sacroiliitis and coxitis in the differential diagnosis of spondyloarthritis

Detection of a phylogenetically distinct IMP-type metallo-beta-lactamase, IMP-35, in a CC235 Pseudomonas aeruginosa from the Dutch-German border region (Euregio)

<p>To characterize a highly divergent IMP-type metallo--lactamase (MBL) variant detected in a multidrug-resistant Pseudomonas aeruginosa clinical isolate.</p><p>P. aeruginosa isolate 1876 was recovered from an anal swab of an inpatient at a German hospital in the DutchGerman border region (Euregio), where cross-border patient healthcare occurs. MICs were determined by agar dilution and phenotypic screening for MBL production by Etest MBL. Typing was performed by multilocus sequence typing (MLST). PCR assays and nucleotide sequencing were employed for identification of bla gene types. The class 1 integron carrying the bla(IMP-type) gene was characterized by PCR mapping and sequencing using a set of specific primers. A phylogenetic tree was constructed for the new bla(IMP) variant.</p><p>Isolate 1876 was phenotypically positive for MBL production, exhibited resistance to carbapenems and harboured a new bla(IMP-type) gene, bla(IMP-35). MLST showed that the allelic profile corresponded to ST622, which belongs to the prevalent international clonal complex CC235. The bla(IMP-35) gene was located in a class 1 integron as the first gene cassette, followed by bla(OXA-35), aacA6, qacE1 and sul1, suggesting its recent integration. IMP-35 was highly divergent, possessing 33/246 (13.4) different amino acid residues from its closest IMP variants (IMP-8 and IMP-12) and was phylogenetically distinct, representing a separate group in the phylogenetic tree of IMP proteins.</p><p>The identification of this phylogenetically distinct IMP-type variant in a CC235 P. aeruginosa suggests the ongoing spread of new IMP-type carbapenemases as well as the potential of the bla(IMP-35) gene to evolve in the hospital environment.</p>