L'objectif de cette étude est d'évaluer la stabilité hémodynamique, l'analgésie peropératoire, ainsi que l'effet sur le nouveau-né des rachianesthésies pratiquées avec une faible dose de bupivacaine ...isobare associées à des doses variables de fentanyl chez les parturientes souffrant de prééclampsie.
30 parturientes, consentantes, ont été colligées de façon prospective et admises au bloc de gynécologie obstétrique pour césarienne programmée sur pré-éclampsie (PE) sévère.
La dose de fentanyl administrée est choisie par le médecin sur place : fentanyl à 10 ¥ (fenta 10 = au nombre de 10), fentanyl à 20 ¥ (fenta 20 = nbre 10) et fentanyl à 25 ¥ (fenta25 = nbre 10).
La fréquence cardiaque, la pression artérielle, le bloc sensoriel sont enregistrés à des intervalles réguliers (2, 4, 6, 10, 20, 30 minutes), ainsi que la présence de douleurs, de nausées, de vomissements, de prurits ou d'autres signes secondaires. L'Apgar a été utilisé pour l'évaluation néonatale (pH ombilical non pratiqué).
L'âge moyen du 1er groupe fenta 10 était de 32,5 années, avec un âge moyen de la grossesse de 38 semaine d'aménorrhée, le 2e groupe fenta 20 : 36 ans, 36 SA, le groupe 3 fenta 25 : 33,5 ans, 37,75 SA.
Un niveau d'anesthésie chirurgicale adéquat a été atteint dans les 3 groupes (niveau T4 moins rapide pour le groupe fenta 10). La chute de la pression artérielle moyenne a été notée pour les 3 groupes à des périodes similaires, mais moins prononcée pour le groupe fenta 30. La durée d'analgésie est presque similaire aux 3 groupes, sans effets secondaires notables (prurit : fenta 30).
L'utilisation de faibles doses de bupivacaine isobare associée à une faible dose de fentanyl permet d'obtenir un niveau d'anesthésie chirurgicale acceptable une durée d'analgésie prolongée sans effets néfastes hémodynamiques ou néonataux chez les patientes pré-éclamptiques admises pour césarienne.
In this study, we address the production planning problem within a hybrid manufacturing remanufacturing system. This system is composed of a single machine that can work in two modes: the first one ...that produces new products from raw materials and the second one that produces remanufactured products from returned used products. Our study is based on economic and environmental considerations where the goal is to determine the best manufacturing and remanufacturing plan that satisfies the demand for new and remanufactured products and simultaneously minimizes the total costs included (start-up, production, storage and disposal costs) as well as the minimization of the CO2 emissions generated by the new, remanufactured and disposed of products. A multi-objective mathematical model is established, and an approach based on a non-dominated genetic sorting algorithm (NSGA-II) is introduced; in addition, a technique of order performance by similarity to the ideal solution (TOPSIS) is used to find the best compromise solution among the pareto front obtained by the NSGA-II algorithm. Finally, a computational experiment is implemented to study the influence of carbon emissions from new, remanufactured and discarded items over a production horizon.
L'ingéniosité du dry-farming, apparu dans les Hautes Plaines Sétifiennes pendant la seconde moitié du 19ème siècle, réside dans la création et le maintien à la surface du sol préalablement labouré ...d'une couche pulvérulente -le mulch terreux- dont la fonction principale est d'empêcher l'évaporation des eaux infiltrées. Dans la pratique, le dry-farming transforme le système biennal céréale-jachère pâturée préexistant et auquel l'élevage, local et transhumant, est intimement associé, en un système céréale-jachère travaillée excluant l'élevage. Le développement du dry-farming, fortement soutenu pour les considérations économiques et politiques de l'époque a eu un impact négatif sur les sociétés rurales, l'élevage et les sols. En un quart de siècle la matière organique des sols et leur fertilité ont chuté de manière notable et, à la hausse initiale des rendements du blé a succédé une baisse qui se poursuivra pratiquement jusqu'à l'indépendance de l'Algérie, jetant le doute sur les vertus du dry-farming. L'agriculture de conservation est une innovation plus récente qui combine la couverture du sol -mulch organique-, le non labour ou le travail réduit et la rotation des cultures. Nombre d'expériences et de résultats de recherches venant d'Espagne, du Maroc ou de la Tunisie soulignent le rôle primordial du mulch organique dans les améliorations qui se produisent dans les sols et font de l'agriculture de conservation une alternative vraisemblable au dryfarming. Il reste que dans les conditions pluviales des Hautes Plaines Sétifiennes, les niveaux de production de biomasse permis risquent de mettre en compétition l'alimentation animale et la couverture du sol, sans oublier qu'en année sèche, les pailles prennent une valeur marchande importante. Par ailleurs, la politique agricole récente a produit beaucoup d'exploitations agricoles de taille réduite dans lesquelles on assisterait à une ré-adoption graduelle de la jachère pâturée et de l'élevage et pour lesquelles la profitabilité de l'agriculture de conservation n'est pas certaine. Les leçons de l'expérience mondiale et les débats en cours sur l'agriculture de conservation incitent à plus d'investigation sur les conditions et les lieux de réussite de systèmes à base d'agriculture de conservation adaptés et leur durabilité dans ces Hautes Plaines.
Plasma spraying is mainly employed for surface treatment providing coating for protection of materials against wear, erosion and corrosion. Improving coating quality requires a better understanding ...of the behavior of the arc created inside the direct current arc plasma torches. The present work is devoted to the determination of plasma torch parameters using an analytical calculation on the cathode spot parameters. A model of a heat transfer in the cathode spot on an electrode in the arc discharge is developed and analytical expressions for the spot radius and temperature as functions of basic characteristics of the discharge and the electrode material are obtained. The dependence of the spot radius on the time, the cathode drop voltage and current is investigated. The sequence of calculation of voltage-current characteristics of DC arc plasma torch is proposed. It is shown that the Steenbeck model of arc discharge in cylindrical channel makes it possible to carry out this calculation.
The Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics were successfully prepared by the sol-gel process and sintered at 1420 °C. The effect of sintering times (2, 4 and 6 h) on structural, microstructural, ...electric properties, energy storage, and electrocaloric effect was systematically examined. X-ray diffraction (XRD) results show that all the samples crystallize in the pure perovskite structure. The morphotropic phase transition from the tetragonal to the orthorhombic phase (T-O) was identified and confirmed by Rietveld refinement. The BCZT ceramic sintered at 1420 °C for 4 h possesses a good relative density of 98% and exhibits optimal properties with a high dielectric permittivity (εr,max) ~16310, a large electrocaloric effect coefficient (ξ) ~ 0.244Kmm/kV and a high energy storage efficiency of 63.65%.
The influence of the incorporation of Calcium in lead-free ferroelectric Ba(Zr0.1Ti0.9)O3 perovskite on its structural phase transition, dielectric, pyroelectric, ferroelectric, and electrocaloric ...effect was investigated. Room temperature X-ray diffraction study allowed the identification of a continuous solid solution in the composition range 0 ≤ x ≤ 20 mol% with a rhombohedral to orthorhombic structural transition beyond 15mol%.Structural investigation of X-ray diffraction as a function of temperature reveals four different structural regions for the compositions with low content of Ca and three regions for the compositions with high Ca-content. Using heat flow measurements and dielectric investigations, two sequences of structural phase transitions were elucidated. The tetragonal-to-orthorhombic and orthorhombic-to-rhombohedral phase transitions induced by temperature variation were found to decrease with the increase of the Ca2+ content, while the cubic-to-tetragonal phase transition temperature remained almost unchanged and exhibited a dielectric permittivity maximum observed around the composition of x = 15mol%.The electrocaloric temperature change ΔT was calculated from two methods: the thermal variation of P–E hysteresis loops and pyroelectric current. The highest electrocaloric ΔT/ΔE = 0.24 K mm/kV was found for the composition x = 0.05. The largest electrocaloric responsivity around 0.30 K mm/kV was observed for this composition at Curie temperature using direct method.
•Ca- doped Ba(Zr0.1Ti0.9)O3 (BZT) perovskite ceramics.•Sequence of phase transitions and phase diagram.•Dielectric and Ferroelectric P-E hysteresis loops versus temperature.•Large Electrocaloric effect.
► Farmers engage in co-innovation platforms to design and implement locally suited conservation agriculture (CA) practices. ► Agro-ecological principles and soil rehabilitation measures are put in ...practice to restore biomass productivity. ► Local knowledge and practices are central in the design of locally suitable CA practices. ► Suitability of CA interventions is evaluated across spatial and temporal scales through integrated model-based assessments. ► ABACO contributes to inform the development of policies that propend towards enabling contexts for smallholders.
Smallholder farmers in semi-arid Africa are in an increasingly vulnerable position due to the direct and indirect effects of climate change, demographic pressure and resource degradation. Conservation agriculture (CA) is promoted as an alternative to restore soil productivity through increased water and nutrient use efficiencies in these regions. However, adoption of CA is low due to a number of technical reasons, but fundamentally due to the fact that CA has been often promoted as a package, without proper adaptation to local circumstances. Farmers engagement in designing and implementing locally suited CA practices, as part of a long term strategy of soil rehabilitation is the core approach followed by the ABACO initiative, which brings together scientists and practitioners from West, East and Southern Africa coordinated through the African Conservation Tillage Network (www.act-africa.org). ABACO relies on agro-ecologically intensive measures for soil rehabilitation and increased water productivity in semi-arid regions, implemented, tested and disseminated through local co-innovation platforms. Rather than using rigid definitions of CA approaches that might not work in all sites, ABACO proposes to explore best engagement approaches for different sites. Simulation modelling is used as a support of long-term cross scale tradeoffs analysis from field to farms and territories, in order to inform effective policy-making. Preliminary results form the field are used here to illustrate and discuss the principles of ABACO, which may apply as well to regions other than semi-arid Africa.
The tetragonal tungsten bronze structural type (TTB) is one of the interesting family where the structure is compatible with a wide variety of cationic substitution that permits tailoring physical ...properties including ferroelectricity, piezoelectricity, nonlinear optics, and energy storage properties. Over the past years, major consideration was devoted to niobate based- tetragonal tungsten bronze, as promising materials for electronic components. In the present work, the conventional solid-state method was used to prepare samples within the NaNbO
3
−BaNb
2
O
6
−MoO
3
system. The structural refinement performed by the Rietveld method and using GSAS-II software, showed that this sample is constituted by two crystalline phases namely Ba
2
Mo
0.80
NaNb
4.20
O
15
and Ba
2
Mo
0.40
NaNb
4.60
O
15
. The first one crystallizes in the P4bm- tetragonal structure with cell parameters of a = b = 12.3762Å and c = 3.98587Å. However, the second was found to crystallize in the orthorhombic symmetry with Pba2 as space group and a = 12.5260 Å, b = 12.42936 Å, and c = 3.97861 Å. Raman spectroscopy was used to get complementary comments on the structure of the BNMO ceramic. The dielectric measurements were carried out from 25 °C to 550 °C and in a frequency range of (10 Hz–1 MHz).
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