Acoustical and thermodynamic study of binary mixture cyclohexane-methanol using ultrasonic interferometer at different temperatures

The ultrasonic velocity (U) mass density (ρ) and shear viscosity (η) of the binary liquid mixtures of cyclohexane-methanol have been determined experimentally in the single-phase region and over the whole composition range at temperature range (T = 321.15 to 325.15 K). The experimental measurements of these properties have been carried out at atmospheric pressure, for a constant frequency 2 MHz. From these experimental data values, various acoustic and thermodynamic parameters namely adiabatic compressibility (βs), acoustic impedance (Z), intermolecular free length (Lf), relaxation time (τ), molar volume (Vm), free volume (Vf), internal pressure (πi), attenuation (α/f2), Gibb’s energy (ΔG), and cohesive energy (CE) have been calculated. Also their excess values have been calculated. All these parameters and their excess values have been interpreted in terms of molecular interaction such as dipole-dipole and dipole induced dipole interactions through hydrogen bonding between components of binary liquid mixture

Required Lateral Inlet Pressure Head for Automated Subsurface Drip Irrigation Management

Subsurface drip irrigation (SDI) is one of the most promising irrigation systems. It is based on small and frequent water supplies. Because SDI emitters are buried, their discharges are dependent on the water status at the vicinity of the outlets. This paper was targeted to design the SDI laterals accounting for the soil water-retention characteristics and the roots water extraction. The proposed approach provides systematic triggering and cut-off of irrigation events based on fixed water suctions in the vadose zone. In doing so, the soil water content is maintained at an optimal threshold ascertaining the best plant growth. Knowing the soil water-retention curve, the appropriate water suction for the plant growth, and the emitter discharge-pressure head relationship, the developed method allows the computation of the required hydraulics of the lateral (e.g., inlet pressure head, inside diameter, etc.). The proposed approach is a helpful tool for best SDI systems design and appropriate water management. An illustrative example is presented for SDI laterals’ design on tomato crop

Change of Diet, Plasma Lipids, Lipoproteins, and Fatty Acids during Ramadan: A Controversial Association of the Considered Ramadan Model with Atherosclerosis Risk

Different Islamic populations have different alimentary habits, notably during Ramadan. The paper reports the change of diet, lipids, and lipoproteins produced during Ramadan in one Tunisian population. During Ramadan, the study subjects consumed more proteins, cholesterol, vitamin E (p<0.01), and polyunsaturated fatty acids (p<0.05). At the same time, they exhibited an increase in total cholesterol, low-density lipoprotein-cholesterol (p<0.01) and apoprotein B (p<0.05) and a decrease in the ratio of apoprotein AI to apoprotein B (p<0.01). All assayed saturated fatty acids were unaffected by Ramadan fasting while three unsaturated fatty acids (C18:1cis9, C18:2n-6, and C30:4n-6) increased significantly. A return to the habitual diet for a four-week period was not sufficient to restore the pre-fasting patterns. For the study subjects, Ramadan was clearly associated with a change of diet and biochemical profile but its effective impact on atherosclerosis risk was unclear, perhaps, because other non-alimentary changes ought to be considered too. Future studies considering the non-alimentary factors, such as sleep and physical activity, would be useful to clarify the contribution of dietary change in the observed modification of biological profile

Efficacy of ovine artificial insemination at farm level in Tunisia

Les inséminations artificielles des brebis (n=3765) réalisées en contre-saison enregistrées durant 3 années successives chez les éleveurs privés ont été analysées afin de déterminer les facteurs influençant la réussite de l’insémination. Les brebis appartenaient à 13 éleveurs adhérant au programme de contrôle des performances de la Direction de l’Amélioration Génétique de l’Office de l’élevage et des Pâturages. Quatre races autochtones: Sicilo-Sarde (SS), Noire de Thibar (NT), Queue Fine de l’Ouest (QFO) et Barbarine tête noire (BTN) et tête rousse (BTR) ont fait l’objet de cette étude. Après avoir reçu un traitement de synchronisation des chaleurs, ces brebis ont subi une insémination cervicale avec du sperme frais ou refroidi à 15°C environ 55 ± 1 h après le retrait de l'éponge. Notre étude a montré que la fertilité des brebis inséminées en contre saison par la technique IA cervicale variait de 32 à 74 % avec une moyenne de 47,6 ± 9,9 %. L’utilisation de la semence refroidie a réduit significativement (p&lt;0,01) le taux de réussite de l’IA avec 43,8 ± 7,6 % contre 55,9 % ± 9,6 % en utilisant la semence fraiche. Nos résultats ont montré la supériorité de la race SS par rapport aux races à viande Tunisienne. Un effet important de la conduite d’élevage a été décelé, montrant l’importance de la préparation des brebis avant le recours à l’IA. Mots clés&nbsp;: Brebis, Fertilité, Insémination cervicaleThe artificial inseminations of ewes (n = 3765) carried out during spring mating season recorded during 3 successive years at private farms were analyzed in order to determine the factors influencing the results of insemination. Ewes belonged to 13 privet breeders adhering to the program of ovine’s performances control of the Department of Genetic Improvement of the Livestock and Pasture Office, Tunisia. Four indigenous breeds: Sicilo-Sarde (SS), Noire de Thibar (NT), Queue Fine de l'Ouest (QFO) and black head (BTN) and red head (BTR) Barbarine were used. Ewes received an estrus synchronization treatment and AI was performed 55 ± 1hours after PMSG administration with fresh or chilled (at 15° C) semen. Our study showed that the fertility of ewes inseminated in out-of-season by the cervical IA technique varied from 32 to 74 % with an average of 47.6 ± 9.9 %. The use of chilled semen significantly (p &lt;0.01) reduced the success rate of AI with 43.8 ± 7.6 % versus 55.9 % ± 9.6 % using the fresh semen. Our results showed the superiority of the SS breed over the Tunisian meat breeds. An important effect of breeding management was detected, showing the importance of preparing ewes before using AI. Keywords: Cervical insemination, Ewes, Fertilit

Change of Diet, Plasma Lipids, Lipoproteins, and Fatty Acids during Ramadan: A Controversial Association of the Considered Ramadan Model with Atherosclerosis Risk

Different Islamic populations have different alimentary habits, notably during Ramadan. The paper reports the change of diet, lipids, and lipoproteins produced during Ramadan in one Tunisian population. During Ramadan, the study subjects consumed more proteins, cholesterol, vitamin E (p&lt;0.01), and polyunsaturated fatty acids (p&lt;0.05). At the same time, they exhibited an increase in total cholesterol, low-density lipoprotein-cholesterol (p&lt;0.01) and apoprotein B (p&lt;0.05) and a decrease in the ratio of apoprotein AI to apoprotein B (p&lt;0.01). All assayed saturated fatty acids were unaffected by Ramadan fasting while three unsaturated fatty acids (C18:1cis9, C18:2n-6, and C30:4n-6) increased significantly. A return to the habitual diet for a four-week period was not sufficient to restore the pre-fasting patterns. For the study subjects, Ramadan was clearly associated with a change of diet and biochemical profile but its effective impact on atherosclerosis risk was unclear, perhaps, because other non-alimentary changes ought to be considered too. Future studies considering the non-alimentary factors, such as sleep and physical activity, would be useful to clarify the contribution of dietary change in the observed modification of biological profile

Étude comparative de la production laitière et de la composition du lait des brebis Sicilo-Sarde dans la région de Mateur et Béja (Tunisie)

The objective of this study was to compare reproductive performance, milk production levels and physico-chemical composition of Sicilo-Sarde ewes raised in Northern Tunisia (Béja and Mateur). The study involved 928 ewes belonging to two farms in the organized sector (a Cooperative Unit of Agricultural Production (UCPA) located in Béja and a flock of the National Office Land in Ghazala -Mateur). Reproduction performance in Béja was high (Fertility: 96% Prolificacy: 138 and numerical productivity: 117.0) its values are much higher than those recorded in Mateur (Fertility: 81.4, Prolificacy: 109.5 and numerical productivity: 82.1). Total milk production in Béja is 124 litres per dairy ewe compared to 30.3 litres/ewe in Mateur with an average daily production of 0.63 litres compared to 0.19 litres. The results obtained showed that the pH, density and freezing point of ewes' milk at Béja and Mateur were comparable. No effect on the physical parameters of the milk of the Sicilo-Sarde ewes. On the other hand, milk fat content was higher for Béja ewes (8.18 % vs 6.69%) Protein contents were comparable for both ewe groups (6.12 % in Béja and 6.13 in Mateur). The low results of the zootechnical parameters are the consequence of failures detected in the conduct of sheep breeding in Mateur. As for milk performance, it seems that the weaning mode and the start date of milking are at the origin of the differences in the performance achieved. &nbsp;Keywords: Dairy sheep, Sicilo-sarde, Tunisia, Weaning, Chemical composition, Zootechnical parametersL’objectif de cette étude est de comparer les performances reproductives, les niveaux de production laitière et la composition physico-chimiques du lait des brebis Sicilo-Sarde élevées dans le nord de la Tunisie (Béja et Mateur). L’étude a concerné un effectif total de 928 brebis appartenant à deux fermes du secteur organisé (une Unité Coopérative de Production Agricole (UCPA) située à Béja et un Agro-combinat de l’Office des Terres Domaniales Ghazala- Mateur). Les performances de reproduction à Béja sont élevées (Fertilité: 96 % ± 6,5 Prolificité: 138,0 ± 21,0 et productivité numérique: 117,0 ±16,0) ses valeurs sont largement supérieures à celles enregistrées à Mateur (Fertilité: 81,4 ± 11,0, Prolificité: 109,5 ± 13,0 et productivité numérique: 82,1 ± 14,0). La production laitière totale à Béja est de 124 litres par brebis laitière contre 30,3 litres/brebis à Mateur avec une production journalière moyenne de 0,63 litre contre 0,19 litre. Les résultats obtenus ont montré que le pH, la densité et le point de congélation du lait des brebis à Béja et Mateur étaient comparables, pas d’effet troupeau sur les critères physiques du lait de la brebis Sicilo-Sarde. En revanche, les valeurs moyennes du taux butyreux sont différentes pour Béja et Mateur (8,18 ±0,38 contre 6,69 ± 1,15). Les valeurs du taux protéique sont très proches (6,12 ± 0,32 % à Béja et 6,13 ± 0,11 à Mateur). La faiblesse des paramètres zootechniques est le résultat de certaines défaillances détectées au niveau de la conduite de la reproduction des troupeaux ovins à Mateur. Quant aux performances laitières, il parait que le mode de sevrage et la date de début de la traite sont à l’origine des différences des performances réalisées. Mots clés&nbsp;: Ovins à lait, Sicilo-Sarde, Tunisie, Sevrage, Composition chimique, Paramètres zootechnique

Required Lateral Inlet Pressure Head for Automated Subsurface Drip Irrigation Management

Subsurface drip irrigation (SDI) is one of the most promising irrigation systems. It is based on small and frequent water supplies. Because SDI emitters are buried, their discharges are dependent on the water status at the vicinity of the outlets. This paper was targeted to design the SDI laterals accounting for the soil water-retention characteristics and the roots water extraction. The proposed approach provides systematic triggering and cut-off of irrigation events based on fixed water suctions in the vadose zone. In doing so, the soil water content is maintained at an optimal threshold ascertaining the best plant growth. Knowing the soil water-retention curve, the appropriate water suction for the plant growth, and the emitter discharge-pressure head relationship, the developed method allows the computation of the required hydraulics of the lateral (e.g., inlet pressure head, inside diameter, etc.). The proposed approach is a helpful tool for best SDI systems design and appropriate water management. An illustrative example is presented for SDI laterals’ design on tomato crop

Mid infrared and fluorescence spectroscopies coupled with factorial discriminant analysis technique to identify sheep milk from different feeding systems

peer reviewedMid infrared spectroscopy (MIR) combined with multivariate data analysis was used to discriminate between ewes milk samples according to their feeding systems (controls, ewes fed scotch bean and ewes fed soybean). The MIR spectra were scanned throughout the first 11 weeks of the lactation stage. When factorial discriminant analysis (FDA) with leave one-out cross-validation was applied, separately, to the three spectral regions in the MIR (i.e. 3000-2800, 1700-1500 and 1500-900 cm(-1)), the classification rate was not satisfactory. Therefore, the first principal component (PCs) scores (corresponding to 3, 10 and 10 for, respectively, the 3000-2800, 1700-1500 and 1500-900 cm(-1)) of the principal component analysis (PCA) extracted from each of the data sets were pooled (concatenated) into a single matrix and analysed by FDA. Correct classification amounting to 71.7% was obtained. Finally, the same procedure was applied to the MIR and fluorescence data sets and 98% of milk samples were found to be correctly classified. Milk samples belonging to control and soybean groups were 100% correctly classified. Regarding milk samples originating from the scotch bean group, only 2 out of 33 samples were misclassified. It was concluded that concatenation of the data sets collected from the two spectroscopic techniques is an efficient tool for authenticating milk samples according to their feeding systems, regardless of the lactation stage. (C) 2011 Published by Elsevier Ltd

Impact of the regression of rangelands on the evolution of breeding systems in Northwest Tunisia

The pastures of northwestern Tunisia have undergone several changes over the last decades.  The main results are the decrease in rangelands, the increase in the total animal load, the increase in the cultivated land, the increase in the production costs particularly the purchase of concentrated feeds, and the low subsidies from the state. All these factors are changing the livestock system, mainly dairy cows. The present study, therefore, sought to characterize farm household systems that seem to be currently adapted in the Sejnane plain using a typology. We focus on understanding the variables that contribute to raising farmers' choice of breeding system in the study area. We interviewed 44 farmers. Furthermore, we analyzed their responses using descriptive statistics, ascending hierarchical classification AMP and principal components analysis PCA. The results show that four types of livestock systems could be characterized, depending on pasture and production. Moreover, they suggest that landless pastoralists are more vulnerable than agro-pastoralists