Modelling thermal effects in agitated vessel and reactor design consideration

The knowledge of the heat transfer coefficient on the inner side of a heated vessel wall is of utmost importance for the design of agitated vessels. The present contribution deals with heat transfer in an agitated vessel containing non-Newtonian liquid. The impellers used are six-blade Turbine (TPD) and a Propeller (TPI). The following aspects are discussed: description of the heat transfer process with the aid of dimensional analysis, heat transfer correlations for agitated liquid and influence of impeller speed on heat transfer

Experimental analysis of short concrete column under hygrothermo-mechanical accelerated aging

Concrete was considered to be very durable material for a long time. However many constructions have shown degradations during their service life. To ensure safety, stability and serviceability of civil engineering structures, understanding of deterioration processes and their effect on the residual structural load capacity is necessary. This paper is based on the experimental study of short prismatic concrete columns under the hygrothermo-mechanical accelerated aging. To investigate the effects of the exposure conditions on the strength of specimens, combined ultrasonic pulse velocity testing and compression loading testing was used. It can be observed from the results obtained in this work that the ultrasonic pulse velocity measurements agree well with the experimental results obtained from the compression loading testing. Results indicate that in first time, degradation of specimens occurs slightly. After that the degradation becomes notable. It also indicates that the degradation due to the combined effect of the hygrothermo-mechanical aging is higher than when we consider hygrothermal and mechanical process separatel

Antioxidant activity, phenolic and flavonoid contents of some wild medicinal plants in southeastern Algeria

This study reported on five plants known for their use in traditional medicine in southeastern Algeria, namely: Artemisia campestris, Asteriscus pygmaeus, Pituranthos chlorantus, Pallenis spinosa and Aizoon hispanicum. The work aimed to determine the antioxidant activity, phenol and flavonoid contents of their aqueous and methanolic extracts. Flavonoids and phenol contents varied according to the nature of the extract and the nature of the plant. Total phenols varied from 30.33 ± 2.03 μg EAG/mg of plant in aqueous extract of Aizoon hispanicum to 280 ± 5.46 μg EAG/mg plant extract in methanolic extract of A. campestris. Flavonoid contents were between 0.071 ± 0.0008 μg QE/mg extract in A. hispanicum aqueous extract and 29.68 ± 0.32 μg QE/mg extract in A. campestris methanolic extract. The aqueous extracts showed the lowest values of flavonoid contents while the methanol extracts showed the highest ones. The antioxidant activities expressed as IC50 values varied from 8.66±1.52 μg/ml for Artemisia aqueous extract, the most active to 325.7±5.50 μg/mL of DPPH solution to the less active Aizoon aqueous extract. The radical scavenging activity decreased in the following order: A. campestris > P. spinosa> P. chlorantus > A. pygmaeus > A. hispanicum.Key words: Antioxidant, flavonoids, phenols, plants

GENETIC CHARACTERIZATION OF OCTOPLOID (AABBDDRR) AND HEXAPLOID (AABBRR) TRITICALES

The genetic variability analysis of octoploid and hexaploid triticales, evidenced by the RAPD-PCR method has allowed the triticales’ (hybrids) differentiation in terms of their ploidy levels corresponding to their primary or secondary nature. The molecular genetic distances derived from Dice’s similarity coefficients are based on 84 RAPD markers of which 40 bands are polymorphic (47.61%). The analysis of the matrix shows that the Sørensen–Dice’s indices of similarity vary between 1 and 0 with an average of 0.52. The dendrogram shows a segregation of three groups: The first group is consists of triticales 8x ([Mahon-demias/ Merced], [KVZ/alb/RC9] and [Mahon-demias/RC9]). The second group is constituted of triticales 6x (LAMB 2 and CHREA) and the third group encloses only FAHAD 6x triticale. It clearly exposed an intraspecific variability (i = 0;i = 0.81; i = 1) and also, the presence an intervarietal polymorphism in the hexaploid group (i=0, i=0,12, i=1) . The latter produced a high number of specific RAPDs (16) whereas the octoploid triticales amplified a lower number (2). This result confirmed that the specific markers (RAPD) are conversely proportional to the ploidy levels. The triticale (FAHAD5) could be a choice material and could be used as a gene donor for the accession of hybrid triticales. Despite the genomic kinship, the important genetic distance between octoploids (AABBDDRR) (D<10) and hexaploids (AABBRR) (D>15) was revealed in this study. This is explained by a genetic differentiation between to the ploidy level

Détermination des concentrations de déoxynivalénol et zéaralénone associées à des maladies chez les vaches laitières

Au Québec, les mycotoxines les plus fréquemment retrouvées dans la ration des troupeaux laitiers sont le déoxynivalénol (DON) et la zéaralénone (ZON). Dans le cadre de notre étude, nous avions deux principaux objectifs. Le premier objectif était de quantifier les mycotoxines DON et ZON chez des vaches laitières naturellement contaminées en évaluant leur présence dans l’aliment, le sérum et l’urine de ces vaches. Le second objectif était de déterminer la mesure dans laquelle ces concentrations de mycotoxines pouvaient être associées à des problèmes de santé, de production et de reproduction chez ces bovins. L’étude s’est déroulée en deux phases. Lors de la première phase, nous avons recensé 60 troupeaux laitiers dans le but d’identifier leurs niveaux de contamination aux mycotoxines. Dans le cadre de la seconde phase, nous avons sélectionné 15 troupeaux présentant les concentrations sériques de Dé-époxy-déoxynivalénol (DOM-1) les plus basses et 15 troupeaux présentant les concentrations de DOM-1 les plus élevées. Ce projet nous a permis d’identifier des concentrations de DON et ZON aux niveaux alimentaire et urinaire qui étaient associées à une augmentation des risques de réforme, d’avortement, de baisse de la performance en reproduction, d’hypercétonémie, d’endométrite clinique et de baisse de la production laitière. Les données ainsi recueillies permettront aux médecins vétérinaires et aux nutritionnistes d’affiner les recommandations qu’ils font aux producteurs laitiers relativement à la gestion des mycotoxines.In Quebec, the most common mycotoxins found in the diet of the dairy herd are deoxynivalenol (DON) and zearalenone (ZON). As part of our study, we had two main objectives. The first objective was to quantify DON and ZON mycotoxins in naturally contaminated dairy cows by assessing their presence in the feed, serum and urine of these cows. The second objective was to determine the extent to which these mycotoxin concentrations could be associated with health, production and reproductive problems in these cattle. The study was conducted in two phases. In the first phase, we carried out 60 dairy herds to identify their levels of mycotoxin contamination. In the second phase, we selected 15 herds with the lowest serum De-epoxy-deoxynivalenol (DOM-1) concentrations and 15 herds with the highest DOM-1 concentrations This project allowed us to identify concentrations of DON and ZON at the dietary and urinary levels that were associated with increased risks of reform, abortion, decreased reproductive performance, hypercetonemia, clinical endometritis And lower milk production. The data collected will allow veterinarians and nutritionists to refine their recommendations to dairy producers regarding the management of mycotoxins

A Study of the Effects of Powdery Mildew (Erysiphe graminis f.sp. avenae) on the Growth and Development of Wild and Cultivated Oats

This thesis reports a study of the relative tolerances of infection by the powdery mildew fungus (Erysiphe graminis f.sp. avenae) in one line of wild oat (Avena fatua) and two cultivars of cultivated oats (Avena sativa). cvs Lustre and Peniarth . The extent to which mildew developed on the three lines was assessed at various stages of growth by measuring percentage leaf area covered, and conidial production per plant and also amounts of chitin produced per unit fresh weight of leaf tissue. At all stages of plant growth, the line of wild oat supported more fungal growth than did cv. Lustre and even more so than cv. Peniarth. The effects of infection on growth and development of the three lines was assessed by growth analysis. In all lines, infection reduced dry matter production and the development of the different plant structures particularly the leaf. The partitioning of photosynthates to different parts of the plant was also altered. Levels of infection of between about 20 and 25% of leaf area infected reduced dry matter production in the cultivated oats but reductions were not evident in wild oat until about 30% of the leaf area was infected. Infection had little or no effect on the pattern of translocation in wild oat whereas it did in the cultivated oats, especially in cv. Peniarth. Reductions in green leaf area were a consequence of losses due to the enhanced senescence of the lower leaves as well as to reductions in the final sizes of the upper leaves. The reduced size of the upper leaves resulted from reduced cell division and cell expansion. All the reductions occurred to a greater extent in the cultivated oats than in wild oat. The reduction in dry matter production was reflected in reductions in yield components in all lines. Infection reduced numbers of tillers, numbers of fertile tillers and the numbers of grains per panicle. The numbers of grains per plant, hundred grain weight and total grain yield were thus reduced although the proportion of total biomass converted to grain (harvest index) was not affected in any of the three lines. Again all the reductions were greater in the cultivated oats than in wild oat. The reduction in dry matter production was partly due to reductions in green leaf area but reductions in the rate of photosynthesis per unit of green leaf tissue were also apparent. The photosynthetic efficiency was measured in infected and uninfected leaf tissue and also in the adjacent uninfected tissue of the infected leaf in wild oat and the cultivated oats using a Hansatech leaf electrode and by fluorescence analysis. The photosynthetic system in the infected tissue was reduced more by low levels of infection in the cultivated oats than by higher levels of infection in the wild oat. Compensatory photosynthesis in adjacent uninfected tissue was also reduced in all plant lines but not to the same extent as photosynthesis in the infected tissue. This was apparent in cv. Lustre but particularly so in wild oat. Thus infected leaves fixed less carbon than uninfected leaves but the total available to the plant and fungus in infected plants was reduced even more since more was lost through enhanced respiration. Measurements of dark respiration showed that infection increased the respiratory rate of infected and adjacent uninfected tissue in all three lines . The reduced rates of photosynthesis could have been due to parasite induced stomatal closure since this would reduce the amount of CO2 diffusing to the carboxylation sites within the chloroplasts of the mesophyll. The effects of infection on stomatal diffusive resistance were measured using an automatic porometer. An increase in diffusive resistance was found in the infected leaves during the light period in all lines around 5 days after inoculation, when mycelium development became significant. This increase in diffusive resistance could reduce the diffusion of CO2 into the leaf to the mesophyll cells and in fact, a reduction in the amount of CO2 reaching the reaction centres in the chloroplasts was evident particularly in the cultivated oats. In contrast, a decrease in diffusive resistance, almost certainly due to greater than normal stomatal opening since mycelium development was between 1 to 2%, was recorded during the dark period in the infected leaves of cultivated oats and wild oat. This decrease was recorded earlier in the cultivated oats than in wild oat. Some of the reduction in photosynthesis was also probably due to reductions in chlorophylls per unit area of leaf tissue. However, these reductions were not directly related to the reductions in photosynthesis since photosynthesis per milligram of chlorophyll in both infected and adjacent uninfected leaf tissue was not affected in any of the three lines. Thus the mechanisms by which photosynthesis was impaired in infected leaves probably involved effects on photosynthetic electron transport after the PSII Qg binding site and thus on the thylakoid proton motive force. However, the exact site of inhibition of the photosynthetic electron transport is uncertain but inhibition may be due to photoinhibition of the Qg binding-protein or impairment of any subsequent component of the photosynthetic electron transport system including PSI. This study showed that all aspects of growth measured were less reduced in wild oat than in the cultivated oats. Thus wild oat appears to be more tolerant of mildew infection than are the cultivated oats. However, the differences in tolerance between wild and cultivated oats were not great enough to suggest that tolerance is likely to be a useful character for inclusion in a conventional breeding programme for crop improvement

Lévy-stable autoregressive model for the federal funds rate

In this paper, we will try to adjust the behaviour of the US Federal Funds interest rate to a model ofautoregressive Levy-stable. We will conduct a series of tests after which it will offer the best model for this data series distributed in time, in this case, a linear model type AR (1) stationary whose distribution i.i.d. innovations would be a stable Lévy law and proceed thereafter to the estimation of nine parameters for this mode