196 research outputs found
Analysis of the thermomechanical inconsistency of some extended hydrodynamic models at high Knudsen number
There are some hydrodynamic equations that, while their parent kinetic equation satisfies fundamental mechanical properties, appear themselves to violate mechanical or thermodynamic properties. This article aims to shed some light on the source of this problem. Starting with diffusive volume hydrodynamic models, the microscopic temporal and spatial scales are first separated at the kinetic level from the macroscopic scales at the hydrodynamic level. Then we consider Klimontovichâs spatial stochastic version of the Boltzmann kinetic equation, and show that, for small local Knudsen numbers, the stochastic term vanishes and the kinetic equation becomes the Boltzmann equation. The collision integral dominates in the small local Knudsen number regime, which is associated with the exact traditional continuum limit. We find a sub-domain of the continuum range which the conventional Knudsen number classification does not account for appropriately. In this sub-domain, it is possible to obtain a fully mechanically-consistent volume (or mass) diffusion model that satisfies the second law of thermodynamics on the grounds of extended non-local-equilibrium thermodynamics
Caractérisation physico-chimique et diversité phytoplanctonique des eaux du lac de Zowla (Lac Boko), Togo
Cette étude a été initiée pour évaluer l’impact de l’eau de mer et des cours d’eau sur les caractéristiques physico-chimiques et sur la diversité phytoplanctonique de l’eau du lac de Zowla. Pour ce faire, cinq sites de prélèvement dans le lac et cinq autres dans les rivières tributaires du lac ont été retenus en Juin 2007 correspondant à la grande saison pluvieuse et en Août 2007 correspondant à la petite saison sèche. Les paramètres physico-chimiques ont été déterminés par les méthodes AFNOR. L’identification des espèces de phytoplancton a été faite au microscope photonique ordinaire. L’étude a révélé une conductivité électrique très élevée d’une valeur maximale de 8370 μS/cm au site le plus proche de la mer en Juin, confirmée par exemple par une teneur en chlorure très élevée (2723 mg /l au même site en Juin). En Août, on note une oxydabilité au KMnO4 élevée (valeur maximale : 10 mgO2/l) aux sites le plus éloigné et le plus proche de la mer. S’agissant de la diversité de la flore algale, les espèces de la classe des diatomophycées sont les plus diversifiées au cours des deux saisons, mais cette suprématie est plus marquée en grande saison pluvieuse qu’en petite saison pluvieuse (80,55% de la composition qualitative de la flore algale en Juin contre 40% en Août). L’Analyse en Composantes principales (ACP) a montré que les cyanophycées sont plus diversifiées en espèces dans les milieux aquatiques turbides riches en éléments minéraux azotés et phosphatés, les euchlorophycées le sont dans les milieux très minéralisés et que les diatomophycées sont cosmopolites. Cette étude montre en outre que les paramètres physico-chimiques du lac de Zowla sont influencés en grande saison des pluies par l’eau de mer et en petite saison sèche par l’eau du fleuve Mono.Mots clés: Pollution, Paramètre physico-chimique, Phytoplancton, La
Nitrogen Moderate Ratesâ Effects on the Performance of Cocoa Seedlings (Theobroma Cocoa Linn.) in the Forest Zone of Togo (West Africa)
The cocoa trees nutrient requirements coverage, especially in nitrogen (N), remains essential for a better growth of the seedlings. The objective of this study was to determine the effects of the moderate nitrogen doses on the agronomic performance of the nursery cocoa seedlings in Togoâs forest zone. Trials were conducted in a complete randomized plot design with four replicates to identify the optimal complementary nitrogen dose helpful for better growth and nutrition of cocoa seedlings. The doses tested were 0; 0.5; 1 and 1.5 g.plant-1 of urea (46% N). The results showed that the doses of 0.5 and 1 g.plant-1 were the most likely to provide the best agronomic performance of nursery cocoa seedlings in the forest zone of Togo. However, the dose of 1 g.plant-1 was optimal for good growth and balanced nutrition of cocoa seedlings and would therefore be recommended for the management of cocoa nurseries in the area
Diversité et dynamique des assemblages phytoplanctoniques dans les écosystÚmes aquatiques au Sud du Togo
L'Ă©tude de la diversitĂ© algale de 4 Ă©cosystĂšmes aquatiques du Sud-Ouest du Togo a permis l'identification de 203 espĂšces dont une centaine est signalĂ©e pour la premiĂšre fois au Togo. Ces espĂšces sont rĂ©parties en 6 embranchements, 29 familles et 85 genres. LâapprĂ©ciation de la dynamique du phytoplancton a permis de constater que la densitĂ© de la population algale est plus importante en grande saison pluvieuse quâen grande saison sĂšche. Son importance est encore beaucoup moindre en petite saison sĂšche quâen petite saison pluvieuse. Quatre paramĂštres physico-chimiques sont mesurĂ©s. Les analyses multivariĂ©es montrent que ces paramĂštres physico-chimiques affectent plus ou moins la distribution spatiale du peuplement algal. Relativement aux groupes phytoplanctoniques identifiĂ©s, plus de 70% des EuglĂ©nophytes sont rencontrĂ©s dans les mares. Par ailleurs, le peuplement phytoplanctonique lagunaire est Ă 58% composĂ© des Chromophytes et celui de la riviĂšre est dominĂ© par les Chlorophytes (40%) et les Cyanophytes (30%).Mots-clĂ©s : diversitĂ© algale, dynamique, paramĂštres physico-chimiques, Ă©cosystĂšmes aquatiques, Sud du Togo.Diversity and dynamic of phytoplankton assemblages in the aquatic ecosystems in south of TogoThe study of algal diversity of four aquatic ecosystems in Togoâs southwestern led to the identification of 203 species including a hundred which is reported for the first time in Togo. These species are divided into 6 phyla, 29 families and 85 genera. The appreciation of the dynamics of phytoplankton showed that the algal population density is higher in long rainy season than dry season. Its importance is much lower in short dry season than in small rainy season. Four physico-chemical parameters are measured. Multivariate analysis showed that these physico-chemical parameters affect greater or lesser the spatial distribution of algal assemblage. In this study, more than 70% of Euglenophyta met in ponds. In addition, the settlement lagoon phytoplankton is composed of 58% Chromophyta and the river is dominated by Chlorophyta (40%) and Cyanophyta (30%).Keywords : algal diversity, dynamic, physico-chemical parameters, aquatic ecosystems, South of Togo
Effect of Moringa oleifera lam. leaves powder on the evolution of hemogram profile in Togolese undernourished children: evaluation on HIV-positive patients
Moringa oleifera Lam. (Moringaceae) leaves have exceptional nutritional qualities and they are used against malnutrition in Africa and Asia. The deficiency corrected by M. oleifera leaves powder administration into daily meal of HIV positive and negative patients has been determined during 14 weeks nutritional recovery by measuring their weight, height and carried hemogram analysis. The study population included infants (20 HIV-positive and 21 HIV-negative) aged from 12 to 30 months and children (26 HIV-positive and 20 HIV-negative) aged 30 months to 9 years. The patients, male and female had anemia or low BMI (body mass index). Results showed that M oleifera use increased significantly BMI (p<0,0001). Weight varied from 1,5 to 2kg and height from 1,8 to 4 cm on the patients. On pilot subjects, variations were very low (p < 0,05). The increase in BMI was significantly different for patients on antiretroviral (ARV) therapy (p < 0,0001) compared to patients without ARV (p <.0,001). Hemogram analysis revealed that M oleifera consumption allowed significant increase (p≤ 0,001) of red blood cell (RBC), hemoglobin (HB), hematocrit (HCT) mean cell volume (MCV), mean cell hemoglobin concentration (MCHC) and (p ≤ 0,01) for mean cellular hemoglobin concentration (CHCM) values. On the other hand, white blood cell parameters were not significantly modified. Hypochromic anemia decreased from 40% to 84% while microcytic anemia decreased from 30% to 84%. On pilot subjects, hemogram parameters did not significantly vary. M. oleifera leaf powder would correct moderate hypochromic anemia better than normochromic anemia whose etiology is folate and vitamin B12 deficit. In addition, these results showed that using M oleifera alone could not correct inflammatory status by reduction of infections on patients. Despite phytates in their leaves, M oleifera powder can be regarded as nutritional supplement and would allow improvement of nutritional status, accelerate immunological recovery and also reinforce the effectiveness of antiretroviral (ARV) drugs on HIV/AIDS patients. Consuming only M oleifera leaves powder, despite its exceptional nutritional benefit, is not a miracle cure. These leaves are neither a drug nor a substitute for antiretroviral drugs
Influence of Moringa oleifera leaves on atherogenic lipids and glycaemia evolution in HIV-infected and uninfected malnourished patients
Objectives: The study evaluated mineral composition of âTogolese ecotypeâ of Moringa oleifera leaves and its effect on anthropometric parameters, atherogenic lipids and glycaemia during nutritional recovery in HIV negative and HIV positive malnourished patients after daily use of the leaves powder.
Methodology and results: Patients aged from 12 months to 8 years, consumed every day for 15 weeks the leaves powder. Results showed that powder is rich in proteins, micronutrients and induced BMI increase in both patients (p C 0.001). Biochemical parameters determination showed decrease in total cholesterol, triglycerides, LDL-cholesterol (p C 0.01), atherogenicity index (AI) correlated with HDL-cholesterol increase (p C 0.001) in HIV negative. Increase in triglycerides, LDL-cholesterol, AI (p C 0.001) correlated with HDLcholesterol decrease (p C 0.001) is observed in HIV positive. Total cholesterol decreased more in HIV positive asymptomatic and increased in patients treated with ARV drugs (p C 0.0001). Glycaemia level is decreased in both patients of the study.
Conclusion and application of findings: This study confirms higher concentrations of proteins, micronutrients, hypolipidemic potential and hypocholesterolemic activity of M. oleifera leaves. This explained nutritional recovery and reduction of atherogenic lipids. Positive effect of the powder on cholesterol metabolism is due to beta-sitosterol, bioactive phytoconstituent of the leaves which fixed LDL particles and thought to be through the lowering significantly of their plasma concentrations. Reduction of glycaemia in both patients confirms also hypoglycemic properties of leaves with high concentration of polyphenols and antioxydants. The lowering of atherogenic risk and glycaemia after regular consumption of M. oleifera leaves powder is more significant in HIV negative than HIV positive patients. Results of this study bring information which will make it possible to pediatrics and nutritionists to adapt better use of M. oleifera leaves to combat malnutrition and the follow-up of HIV positive persons and in particular those on antiretroviral treatment.
Key words: Moringa oleifera, malnutrition, atherogenic lipids, glycaemia, HIV/AIDS
Diversity of agroecosystems and ecosystem services gain for agrobiodiversity conservation in agricultural landscape in northern Togo
To tackle food insecurity and alleviate rural poverty, the Togolese government initiated a novel form of land-based investment in rural agriculture named «Kara agropole», which promotes the cultivation of maize, rice, sesame, soybean and cashew mainly for commercial and industrial purposes. This study analyses the agricultural diversity as a baseline to foster the sustainable management of agrobiodiversity while implementing the project. The study was carried out in 11 counties from 4 districts (Bassar, Dankpen, Doufelgou and KĂ©ran) in Kara region. A survey of 115 households was conducted to collect data about agricultural practices. Botanical inventory had been carried out in 60 square plots of 25mx25m to evaluate the current agrobiodiversity and to identify ecosystem services. Data analysis matching with empirical field observations showed that there are 6 types of agroecosystems (pure cropping â crop rotation, intercropping, agroforestry, forestry, fallow lands and pasture lands) in the area with pure cropping as the main agricultural practice. Provisioning services turn out to be of the highest interest to the survey respondents for annual and perennial species. Therefore, a landscape approach that strikes a balance between agricultural land use and conservation might help to conserve more agrobiodiversity and promote other categories of ecosystem services.
Keywords: Agroecosystems, ecosystem services, species, sustainable agriculture, Togo.
French title: Diversite des agroecosystemes et benefice des services ecosystemiques pour la conservation de lâagrobiodiversite en paysage agricole au nord TogoPour lutter contre lâinsĂ©curitĂ© alimentaire et la pauvretĂ© rurale, le gouvernement togolais a lancĂ© une nouvelle forme dâinvestissement foncier en agriculture rurale, appelĂ©e « agropole de Kara », favorisant la culture du maĂŻs, du riz, du sĂ©same, du soja et de lâanacarde aux fins commerciales et industrielles. La prĂ©sente Ă©tude analyse la diversitĂ© agricole comme rĂ©fĂ©rence pour favoriser la gestion durable delâagrobiodiversitĂ© pendant la mise en Ćuvre du projet. LâĂ©tude est rĂ©alisĂ©e dans 11 cantons de 4 prĂ©fectures (Bassar, Dankpen, Doufelgou et KĂ©ran) de la rĂ©gion de Kara. Une enquĂȘte menĂ©e auprĂšs de 115 mĂ©nages a recueilli des donnĂ©es sur les pratiques agricoles. Lâinventaire botanique est rĂ©alisĂ© dans 60 parcelles carrĂ©es de 25mx25m pour Ă©valuer lâagrobiodiversitĂ© prĂ©sente et identifier les services Ă©cosystĂ©miques. Lâanalyse de donnĂ©es couplĂ©es Ă lâobservation empirique montrent lâexistence de 6 types dâagroĂ©cosystĂšmes (culture pure, cultures associĂ©es, agroforesterie, sylviculture, jachĂšre et pĂąturage) dans la zone, avec la culture pure comme principale pratique agricole. Les services dâapprovisionnement sont dâun grand intĂ©rĂȘt aux rĂ©pondants enquĂȘtĂ©s pour les espĂšces annuelles et pĂ©rennes. Par consĂ©quent, lâapproche paysage qui Ă©tablit un Ă©quilibre entre utilisation et conservation des terres agricoles pourrait contribuer Ă conserver davantage lâagrobiodiversitĂ© et promouvoir dâautres catĂ©gories de services Ă©cosystĂ©miques.
Mots-clés : AgroécosystÚmes, services écosystémiques, espÚces, agriculture durable, Tog
Effets dâun acide fort sur la rĂ©action de la DPPH avec deux huiles essentielles de deux plantes aromatiques acclimatĂ©es au Togo
Des Ă©tudes ont montrĂ© que les extraits de certaines plantes mĂ©dicinales ainsi que leurs huiles essentielles (HE) sont sources de substances bioactives avec de potentiels antioxydants remarquables. Lâobjectif de ce travail est lâĂ©tude de lâinfluence du milieu rĂ©actionnel sur lâaction des HE des plantes, de O. basilicum et O. gratissimum acclimatĂ©es au Togo, sur la 2,2-diphĂ©nyl-1-picrylhydrazyle. Les constituants chimiques des HE sont identifiĂ©s par la chromatographie en phase gazeuse. Le test de rĂ©duction de la 2,2-diphĂ©nyl-1-picrylhydrazyle (DPPH) et celui de rĂ©duction de lâion ferreux Fe2+ (FRAP) sont utilisĂ©s pour dĂ©terminer la capacitĂ© antioxydante. Les propriĂ©tĂ©s antioxydantes des HE ont Ă©tĂ© mises en Ă©vidence par la recherche de lâintensitĂ© colorante (IC50) et la dĂ©termination de lâĂ©quivalent en Fe2+ des solutions testĂ©es. Lâintroduction dâun acide fort (acide chlorhydrique) influence les paramĂštres cinĂ©tiques. Les huiles essentielles étudiĂ©es contiennent le thymol et l'eugĂ©nol et sont anti oxydants. Toutefois, en se rĂ©fĂ©rant Ă la classification de Sanchez-Moreno, ces huiles essentielles ont un pouvoir anti-radicalaire faible. Dans lâintervalle de concentrations Ă©tudiĂ© [0,025-0,1] M, la rĂ©action est accĂ©lĂ©rĂ©e les cinq premiĂšres minutes avec un taux de conversion, comme la vitesse de rĂ©action trĂšs Ă©levĂ©s. Le mĂ©canisme (electron transfer â proton transfer) est prĂ©dominant. Lâaugmentation de la concentration en HCl et le temps ont favorisĂ© le mĂ©canisme SPLET. Cette étude a montrĂ© que les huiles essentielles Ă©tudiĂ©es ont un pouvoir anti-radicalaire faible mais, elles ont des vitesses de rĂ©action intermĂ©diaires avec la DPPH.© 2015 International Formulae Group. All rights reserved.Mots clĂ©s: O. basilicum et O. gratissimum, DPPH, antioxydant, facteurs cinĂ©tiques, huiles essentiellesEnglish Title: Effects of a strong acid on the reaction of DPPH with two essential oils from two aromatic plants acclimatized in TogoEnglish AbstractStudies have shown that extracts of certain medicinal plants as their HE are sources of bioactive substances with potential remarkable antioxidants. The objective of this work is to study the influence of the reaction medium on the essential oils, O basilicum and O gratissimum, from Togo, their action on 2,2-dipheny-1-picrylhydrazyl. The chemical constituents of essential oils are identified using gas chromatography. The reduction tests with DPPH and reduction of Fe2+ ion (FRAP) are used to determine the antioxidant capacity. Antioxidant properties of the essential oils are shown up by the detection of colored intensity (IC50) and by the determination of Fe2+ ion equivalent in the solutions. The addition of a strong acid (HCl) influences the kinetic parameters. The studied essential oils contain thymol and eugenol and are antioxidants. Although, based on the Sanchez-Moreno classification, these essential oils have weak antiradical activity. Within the studied concentration range from 0.025M to 0.1M, the reaction runs fast in the first five minutes as well as a high reaction speed. The mechanism (electron-proton transfer) is predominant. Increasing time and HCl concentration favored SPLET mechanism. This study showed that essential oils studied have low anti-radical power, but they have intermediate reaction rates with DPPH.© 2015 International Formulae Group. All rights reserved.Keywords: O. basilicum, O. gratissimum, DPPH, antioxidant, kinetic factors, essential oil
Variation de la densitĂ© et la couleur du bois de Pterocarpus erinaceus (Poir) en fonction des conditions environnementales en Afrique de lâOuest
National audiencePterocarpus erinaceus (Poir.) is currently spontaneous species of Guinea-Sudanese and Sudano-Sahelian areas overexploited and threatened in West Africa. This paper analyzes the density and color of the wood of the species in the agro-ecological zones of three countries in West Africa (Togo, Burkina Faso and Niger). The results of 452 samples collected from 95 trees from the three countries show significant differences in values of basic density and color parameters (P <0.05) according to agro-ecological zones (Sudan, Guinea and Sahel). At scale intra-tree, even if there is an increase in density with the number of rings counted from the pith, this increase is very small (RÂȆ0.18). This reflects the fact that age has little influence on the trees density. In addition, a significant correlation was observed between density and color parameters.Pterocarpus erinaceus (Poir.) est actuellement lâespĂšce spontanĂ©e des zones guinĂ©o-soudaniennes et soudano-sahĂ©liennes trĂšs exploitĂ©e et menacĂ©e en Afrique de lâOuest. Le prĂ©sent travail analyse la densitĂ© et la couleur du bois de lâespĂšce dans les zones agroĂ©cologiques de trois pays de lâAfrique de lâOuest (Togo, Burkina Faso et Niger). Les rĂ©sultats obtenus sur 452 Ă©prouvettes prĂ©levĂ©es de 95 arbres issus des 3 pays indiquent des diffĂ©rences significatives des valeurs de lâinfradensitĂ© et des paramĂštres de couleur (P<0,05) en fonction des zones agro-Ă©cologiques (soudanienne, guinĂ©enne et sahĂ©lienne). A lâĂ©chelle intra-arbre, mĂȘme sâil ya une augmentation de la densitĂ© en fonction du nombre de cernes comptĂ©s, depuis la moelle, cette augmentation est trĂšs faible (RÂȆ0,18). Ce qui traduit le fait que lâĂąge des arbres influence peu lâinfradensitĂ©. Par ailleurs une corrĂ©lation significative a Ă©tĂ© observĂ©e entre la densitĂ© et les paramĂštres de couleur
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