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Search Results: 1 - 10 of 1025 matches for " Tidra Vi "
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Total Nitrogen and Available Phosphorus Dynamics in Soils Regenerating from Degraded Abandoned Rubber Plantation in Orogun Area of the Rainforest Zone of Southern Nigeria
VI Ichikogu
Ethiopian Journal of Environmental Studies and Management , 2012,
Abstract: Total nitrogen and available phosphorus concentration of soils in three secondary forest fields aged 1, 5 and 10 years of age regenerating from degraded abandoned rubber plantation (Hevea brasiliensis) and a mature forest in the west African Rainforest belt in southern Nigeria were investigated in order to determine the trend of change in the properties of soil in secondary forest during the course of forest restoration from degraded deserted rubber plantation (Hevea brasiliensis). There was a continuous increase in the concentration of total nitrogen in the soil (both topsoil and subsoil). The concentrations of total nitrogen and available phosphorus in the topsoil are higher than the subsoil. The concentration of available phosphorus during the first five years of secondary forest regeneration increased, after which their values declined by the tenth year in both the topsoil and the subsoil. Should this trend of decline in the concentration of phosphorus continue phosphorus may become a limiting factor to plant growth the older the secondary forests become.
The Dynamics of Soil Physical Properties and Exchangeable Cations in Secondary Forests Regenerating from Degraded Abandoned Rubber Plantation (Hevea brasiliensis) in Orogun Area of Southern Nigeria
VI Ichikogu
Ethiopian Journal of Environmental Studies and Management , 2011,
Abstract: The regeneration of soil physicochemical properties in three secondary forest fields aged 1, 5 and 10 years of age following the abandonment of degraded rubber (Hevea brasiliensis) plantation in Orogun were investigated. In addition a mature forest was selected and investigated as the control. Values of important indices of soil physicochemical parameters were ascertained for the three secondary forests categories and the mature forest. The results obtained revealed that there was no significant improvement or changes in soil particle size composition during the course of secondary forest regeneration. The concentrations of the exchangeable cations were higher in the mature forest than the different secondary forest categories. Soil bulk density decreased while water holding capacity and total porosity of soil increased with increasing age of secondary forest. Exchangeable cations improved in the first five year of secondary forest regeneration, after which their values declined by the tenth year in the topsoil (0-10cm layer). Similarly, exchangeable potassium and sodium improved significantly in the subsoil (10-30cm layer) by the fifth year of secondary forest regeneration from degraded abandoned rubber plantation, after which their values declined by the tenth year. However, exchangeable magnesium and calcium declined in the subsoil throughout the course of forest recovery. Effective cation exchange capacity in the topsoil and the subsoil increased linearly with increasing age of secondary forest, while soil pH decreased with increasing age of secondary forest. These results demonstrate that fallowing exerts beneficial effects on soil fertility (i.e. soil fertility improved as fallow age increased).
Organic Matter Dynamics in Soils Regenerating from Degraded Abandoned Rubber Plantation in Orogun Area of the Rainforest Zone of Southern Nigeria
VI Ichikogu
Ethiopian Journal of Environmental Studies and Management , 2011,
Abstract: The area of secondary forest (SF) regenerating from degraded abandoned rubber (Hevea brasiliensis) plantation is increasing in the rainforest zone of south southern Nigeria; however, the build-up of soil organic matter following abandonment is not well understood. This study examined the build-up of soil organic matter in a mature forest and three secondary forest fields aged 1, 5 and 10 years of age following the abandonment of degraded rubber (Hevea brasiliensis) plantation in Orogun in a part of the rainforest zone of south southern Nigeria. This is in order to ascertain the rate of build-up of organic matter in the soil during the course of forest regeneration from degraded abandoned rubber plantation (Hevea brasiliensis). There was a progressive increase in organic matter content of the soil with increasing age of the secondary forest. Organic matter increase was more rapid in the topsoil (0-10cm) than the subsoil (10-30cm): the level of organic matter in the topsoil reached 92.94% of the level of organic matter in the mature forest topsoil by the tenth year and 84.62% of the level of organic matter in the mature forest subsoil by the tenth year. The concentration of organic matter in the topsoil is higher than the subsoil. Reviews of the reported trends in soil organic matter build up during forest establishment after agricultural use show no common trend. This study showed a great variation in soil organic matter build up even within the same locality.
Membranas de impermeabilización y láminas geotextiles filtrantes
Vié, George
Informes de la Construccion , 1979,
Abstract: Georges Vié, Mining engineer This article deals with the various uses of non-traditional products: — the bituminous membrane, used for solving water-proofing problems in tanks and ponds having a relatively low water load, — the geotextile coating of non-woven sinthetic fibers, used because of their filtering capacity in the construction of the runway In the Marignane (Marseille) airfield. Se exponen en este artículo varios usos de productos no tradicionales: — la membrana bituminosa, que sirve para resolver problemas de impermeabilización en depósitos y embalses, con carga de agua relativamente débil, y — la lámina geotextil, de fibras sintéticas no tejidas, utilizada por su poder filtrante en la construcción de la pista de despegue del aeródromo de Marignane (Marsella). Se explican también las principales características técnicas de estos materiales.
Los últimos progresos en perforación de minas, galerías y canteras
Vié, G.
Informes de la Construccion , 1978,
Abstract: Important progress has been achieved in recent years in the field of drilling and excavation. This article studies some of these improved methods, both in the area of machines and equipment and the explosives field. The potential areas of application of rotary drilling and hydraulic rotary-percussion drilling, the uses for the borehole bottom hammer, the properties of powder and liquid explosives and their possible applications, etc., are examined. Ha habido, durante estos últimos a os, notables progresos en el campo de la perforación. En este artículo se analizan algunos de ellos, tanto en el campo de maquinaria y herramientas, como en el de los explosivos. Se ven los posibles campos de la perforación rotativa y la roto-percusión hidráulica, los usos del martillo fondo del taladro , las características y posibles usos de los explosivos líquidos o pastosos, etc.
Hormigones ligeros y obras públicas. Francia
Vié, G.
Informes de la Construccion , 1982,
Abstract: Not available. Entre las causas del empleo, cada vez más amplio, del hormigón ligero frente al hormigón tradicional se encuentran: menor peso, menor contracción durante el fraguado, transporte menos costoso, colocación y manejo más fácil, etc. En este artículo se describe la realización de una pasarela en Grenoble (Francia), de 125,70 m de longitud, de los cuales 68,80 son de hormigón ligero. El tablero, de una anchura de 6,7 m de longitud y pretensado longitudinalmente, está formado por una viga-cajón de 1,5 m de altura e inercia constante. La cimentación se realizó sobre pilotes de 800 a 1.000 mm de diámetro prefabricados in situ. Los estribos son del tipo contrapeso. La pasarela se construyó en dos mitades, cada una de ellas sobre una orilla del río Isère, uniéndose posteriormente una vez colocadas en su emplazamiento final.
Construcción de túneles mediante máquinas que excavan a sección total (tuneladora) y normas para su utilización
Vié, G.
Informes de la Construccion , 1980,
Abstract: In this article an analysis is made of several interesting results obtained by the use of nonstop drilling machines in various recent w/orks, as well as different improvements carried out follow/ing a number od studies and tests. From this analysis it can be concluded that these machines are only profitable for extensive lengths, and that it is necessary to carry out prior geological studies before commencing drilling operations. Among the improvements are found: the use of activated teeth, whereby the static pressure forces are replaced by dynamic processes; the placement of high-pressure water blasts next to the drilling tools, thus increasing the cutting power; the use of hydraulic transport in small-diameter galleries; the use of aminoplast resin reinforced with fiberglass in order to enhance leakproofness and to improve the lining of the tunnels; etc. En este artículo se analizan algunos resultados interesantes obtenidos por el empleo de máquinas de perforación continua en varias obras de reciente ejecución, así como diversas mejoras realizadas después de diferentes estudios y ensayos. De este análisis se deduce que estas máquinas sólo son rentables para grandes longitudes y que es preciso realizar estudios geológicos previos antes de comenzar la perforación. Entre las mejoras producidas están: la utilización de muelas activadas, con las que se consigue sustituir las fuerzas de presión estática por procesos dinámicos; la colocación de chorros de agua a alta presión junto a las herramientas de perforación, con lo que se aumenta la potencia de corte; el uso del transporte hidráulico en galerías de peque o diámetro; el empleo de resina aminoplasta armada con fibras de vidrio para aumentar la estanquidad y mejorar el revestimiento de los túneles; etc.
Excavaciones subterráneas con máquinas tuneladoras
Vié, G.
Informes de la Construccion , 1983,
Abstract: Not available. La reducción del coste de excavación de una galería mediante la utilización de una máquina tuneladora es evidente y, de ahí, la constante búsqueda de mejoras técnicas y condiciones de uso. Se designan, normalmente, con el nombre de tuneladoras a las máquinas de este tipo empleadas en obras públicas, mientras que se denominan minadores continuos cuando se utilizan en las minas.
IMMUNOLOGY OF A CANCER
Cherniavsky VI
Annals of Mechnikov's Institute , 2012,
Abstract: The lecture deals with the problem of immune response in cancer. Lecture for physicians of all specialties, pharmacists and biologists interested in the problem of immune response to cancer.
BACTERIAL BIOFILMS AND INFECTION (LECTURE)
Chernjavsky VI
Annals of Mechnikov's Institute , 2013,
Abstract: The lecture presents published data on the biofilm – a special from of organization of the microflora of the human body, the role of microbial biofilms in the genesis and development of many common diseases. Different mechanisms of antimicrobial resistance development in biofilm are reviewed in the article
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