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Search Results: 1 - 10 of 401279 matches for " Jafet M.; Semprum "
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Pulpa del fruto del cardón dato (Stenocereus griseus, Cactaceae) como materia prima para la elaboración de mermelada
Emaldi,Unai; Nassar,Jafet M.; Semprum,Carla;
Archivos Latinoamericanos de Nutrición , 2006,
Abstract: this study aimed to examine the possibility of producing marmalades from the fruit pulp of the red and white varieties of cardón dato (stenocereus griseus). we developed the formulations of the marmalades and evaluated their stability during three months of storage at room temperature. as first step, we characterized the fruits of the two color varieties, observing that despite the considerable difference between both color varieties, there were no significant differences in average weight, dimensions and proportion of pulp, skin and seeds. the pulp of the two color types had high ph (5,2) values and low contents of reductor sugars (3,59 g/100g white variety 2,23 g/100g red variety), non reductor sugars (0,75 g/100g white variety and 2,03 g/100g red variety), pectin (0,14 g/100g white variety and 0,23 g/100g red variety) and acids (7,67 g/100g white variety and 0,15 g/100g red variety). it is needed to include sugar, pectin, and citric acid in the marmalade formula. the first marmalades produced were gummy, a problem that we solved adding the acid from the beginning of the making process. during the three months of storage, the marmalades had good acceptance by the evaluators, this despite slight fluctuations observed in ph, solid contents, and acidity.
Fenología reproductiva y capacidad de regeneración de dos cardones, stenocereus griseus (haw.) Buxb. Y cereus repandus (l.) Mill. (cactaceae)
Nassar,Jafet M; Emaldi,Unai;
Acta Botánica Venezuelica , 2008,
Abstract: stenocereus griseus and cereus repandus are two of the most abundant and widely distributed columnar cacti in the arid and semiarid regions of venezuela. despite their value as keystone species for wildlife and their potential economic value, information on their reproductive activity and regeneration capacities is quite limited. these aspects were evaluated in natural populations from padre diego, lara state, and paraguana peninsula, falcon state. these cacti have broad time windows for reproduction and considerably high fecundity levels (s. griseus: 44,225 seeds/ind, c. repandus: 322,749 seeds/ind), which confer them great advantages in terms of natural regeneration and propagation. these species depend on nurse plants for their establishment. the highest percentages of survival occurred under the shadow of trees. under natural conditions, these species can produce half a ton of fruit pulp per hectare.
Fenología reproductiva y capacidad de regeneración de dos cardones, stenocereus griseus (haw.) Buxb. Y cereus repandus (l.) Mill. (cactaceae) Reproductive phenology and regeneration capacity of two cardones, Stenocereus griseus (Haw.) Buxb. and Cereus repandus (L.) Mill. (Cactaceae)
Jafet M Nassar,Unai Emaldi
Acta Botánica Venezuelica , 2008,
Abstract: Stenocereus griseus y Cereus repandus son dos de las cactáceas columnares más abundantes y ampliamente distribuidas en las regiones áridas y semiáridas de Venezuela. A pesar de su valor como especies clave para la fauna silvestre y de su potencial valor económico, la información sobre su actividad reproductiva y capacidad de regeneración es muy limitada. Dichos aspectos fueron evaluados en poblaciones naturales de Padre Diego, estado Lara y la Península de Paraguaná, estado Falcón. Estos cactus poseen patrones reproductivos temporalmente amplios y niveles de fecundidad elevados (S. griseus: 44.225 semillas/ind, C. repandus: 322.749 semillas/ind), que les confieren grandes ventajas para su regeneración natural y propagación. Estas especies dependen de plantas nodriza para su establecimiento, presentando los porcentajes más elevados de supervivencia bajo la sombra de árboles. En condiciones naturales, estas plantas rinden media tonelada de pulpa de fruta por hectárea. Stenocereus griseus and Cereus repandus are two of the most abundant and widely distributed columnar cacti in the arid and semiarid regions of Venezuela. Despite their value as keystone species for wildlife and their potential economic value, information on their reproductive activity and regeneration capacities is quite limited. These aspects were evaluated in natural populations from Padre Diego, Lara State, and Paraguana Peninsula, Falcon State. These cacti have broad time windows for reproduction and considerably high fecundity levels (S. griseus: 44,225 seeds/ind, C. repandus: 322,749 seeds/ind), which confer them great advantages in terms of natural regeneration and propagation. These species depend on nurse plants for their establishment. The highest percentages of survival occurred under the shadow of trees. Under natural conditions, these species can produce half a ton of fruit pulp per hectare.
Sincronía reproductiva interpoblacional de Agave cocui (Agavaceae) en Venezuela
Figueredo,Carmen J; Villegas,José Luis; Nassar,Jafet M;
Revista de Biología Tropical , 2011,
Abstract: interpopulation reproductive synchrony of agave cocui (agavaceae) in venezuela. agave cocui (agavaceae) is a species with broad distribution in arid and semiarid areas of venezuela and colombia. despite of its ecological importance as a source of food for wildlife, and its economic value for production of a spirit drink, studies on the reproductive ecology of the species are relatively rare. in this study, we conducted a oneyear evaluation of the flowering and fruiting phenology of a. cocui in the eight representative localities of the species’ distribution in venezuela. within each study site, we chose an area with a minimum of 50 reproductive individuals and followed their reproductive phenophases with the help of binoculars, using six qualitative cathegories (emerging reproductive stalk, flowers, inmature fruits, mature fruits, bulbils and dry stalk) every two months. emergence of the reproductive stalk in most of the examined populations began in september (rainy season), although this event delayed two months in a few populations. we detected significant negative correlations between precipitation and the percentage of flowering occurrence in four of the eight populations. floral resources are available for flower visitors during approximately five months of the year (january-may). in most populations production of flowers initiated in january (dry season), and for western venezuela and andean regions, the flowering main peak occurred in january. localities from the central and eastern coast exhibited the flowering peak in march, showing a delay of approximately two months with respect to other populations. beginning of fruit set varied among localities from january to may; however, peak production of mature fruits concentrated in may, and fruit occurrence varied broadly between 5.2 and 85%. bulbil production was detected in all populations and varied greatly among them (maximum percentage per population: 26.19-92.10%). high flowering synchronicity (phenophase
Variación morfométrica floral en Pachira quinata (Jacq.) W.Alverson (Bombacaceae) Floral morphometric variation in Pachira quinata (Jacq.) W.Alverson (Bombacaceae)
Nelson Ramírez,Jafet M Nassar,Lino Valera,Vicente Garay
Acta Botánica Venezuelica , 2010,
Abstract: La variación morfométrica floral de clones de Pachira quinata fue evaluada bajo condiciones de cultivo en los jardines y huerto clonal semillero de El Irel, Barrancas, estado Barinas, Venezuela. Seis caracteres métricos florales fueron considerados: diámetro externo, diámetro interno, diámetro del tubo de la flor, largo de la flor, largo del tubo floral y hercogamia para 92 flores de 20 clones de procedencia venezolana y 51 flores de 10 clones de procedencia centroamericana. La mayoría de las dimensiones florales están correlacionadas positivamente para la procedencia suramericana, mientras que sólo cuatro pares de caracteres morfométricos, relacionados con el largo y diámetro floral, resultaron significativos para la procedencia centroamericana. Los seis caracteres florales difirieron estadísticamente entre todas las localidades. El diámetro externo, diámetro del tubo, largo de la flor y hercogamia fueron mayores para las procedencias suramericanas, y el diámetro interno y largo del tubo floral fueron mayores para las procedencias centroamericanas. De acuerdo al análisis discriminante, las características florales permiten, con pocas excepciones, diferenciar las procedencias de los individuos evaluados; sin embargo, existe un amplio rango de variación, ya que sólo 65% de las flores son asignadas correctamente a sus localidades. El análisis multivariado mostró diferencias significativas entre flores procedentes de Centroamérica y Suramérica. Los caracteres florales que permiten distinguir entre áreas geográficas fueron en orden de importancia: 1. hercogamia, 2. diámetro externo, 3. largo del tubo, y 4. diámetro interno, los cuales permitieron discriminar correctamente un alto porcentaje de flores de acuerdo a su procedencia geográfica (86,9%). Las variaciones de los caracteres morfométricos florales en la especie son discutidas con relación a su sistema de entrecruzamiento, modo de polinización y distribución geográfica. Variation in floral morphometry of Pachira quinata was evaluated for clones under cultivation conditions at the Irel Station, Barrancas, Barinas State, Venezuela. Six metrical floral traits were considered: floral external diameter, floral internal diameter, diameter of floral tube, floral length, flower tube length, and herkogamy for 91 flowers from 20 Venezuelan clones and 51 flowers from ten Central American clones. Most floral dimensions were positively correlated for South American flowers, and only four pairs of morphometrical floral traits resulted statistically significant for Central American flowers, mainly related with floral
Sincronía reproductiva interpoblacional de Agave cocui (Agavaceae) en Venezuela
Carmen J Figueredo,José Luis Villegas,Jafet M Nassar
Revista de Biología Tropical , 2011,
Abstract: cocui (Agavaceae) es una especie de amplia distribución en zonas áridas y semiáridas de Venezuela y Colombia. A pesar de su importancia ecológica como fuente de recursos para la fauna silvestre y de su potencial valor económico como materia prima para la producción del licor “Cocuy de Penca”, los estudios sobre su ecología reproductiva son muy escasos. En este estudio se evaluó la fenología de floración y fructificación de A. cocui en ocho localidades de Venezuela. La fase reproductiva se inició al finalizar el periodo de lluvias. Las flores se producen durante cinco meses. Para la Región Noroccidental del país y los Andes los máximos de floración ocurrieron en enero, mientras que las localidades en la costa central y oriental exhibieron un desface de cerca de dos meses, a principios de marzo. La mayor sincronía floral ocurrió entre todas las poblaciones censadas en el occidente del país, incluyendo las localidades andinas. Dicha sincronía reproductiva potenciaría la conformación de un corredor de néctar para aves y murciélagos, que se extendería desde el Norte de Falcón, en la Costa Occidental, hasta los bolsones andinos, en el Suroeste del país. Interpopulation reproductive synchrony of Agave cocui (Agavaceae) in Venezuela. Agave cocui (Agavaceae) is a species with broad distribution in arid and semiarid areas of Venezuela and Colombia. Despite of its ecological importance as a source of food for wildlife, and its economic value for production of a spirit drink, studies on the reproductive ecology of the species are relatively rare. In this study, we conducted a oneyear evaluation of the flowering and fruiting phenology of A. cocui in the eight representative localities of the species’ distribution in Venezuela. Within each study site, we chose an area with a minimum of 50 reproductive individuals and followed their reproductive phenophases with the help of binoculars, using six qualitative cathegories (emerging reproductive stalk, flowers, inmature fruits, mature fruits, bulbils and dry stalk) every two months. Emergence of the reproductive stalk in most of the examined populations began in September (rainy season), although this event delayed two months in a few populations. We detected significant negative correlations between precipitation and the percentage of flowering occurrence in four of the eight populations. Floral resources are available for flower visitors during approximately five months of the year (January-May). In most populations production of flowers initiated in January (dry season), and for Western Venezuela and Andean regions, the
Variación morfométrica floral en Pachira quinata (Jacq.) W.Alverson (Bombacaceae)
Ramírez,Nelson; Nassar,Jafet M; Valera,Lino; Garay,Vicente; Brice?o,Herbert; Quijada,Marcelino; Moret,Yajaira A; Montilla,Jorge;
Acta Botánica Venezuelica , 2010,
Abstract: variation in floral morphometry of pachira quinata was evaluated for clones under cultivation conditions at the irel station, barrancas, barinas state, venezuela. six metrical floral traits were considered: floral external diameter, floral internal diameter, diameter of floral tube, floral length, flower tube length, and herkogamy for 91 flowers from 20 venezuelan clones and 51 flowers from ten central american clones. most floral dimensions were positively correlated for south american flowers, and only four pairs of morphometrical floral traits resulted statistically significant for central american flowers, mainly related with floral length and floral diameter. all floral traits differed according to clone origin. floral external diameter, diameter of floral tube, floral length, and herkogamy were larger for south american clones, and floral internal diameter and flower tube length were larger for central american clones. morphometrical floral traits allow us to discriminate between geographical origins of clones. however, there is a broad range of variation, since only 65% of flowers were properly classified according geographical locality. a second discriminant analysis, using morphological traits, showed significant differences between south and central american flowers. in order of importance, floral traits that allow discrimination between geographic areas are as follows: 1. hercogamy, 2. external diameter, 3. tube length, and 4. internal diameter. these traits correctly discriminated a high percentage (86.9%) of flowers according to geographic origin. morphometrical variations of floral traits are discussed in relation to its breeding system, pollination mode and geographical distribution.
Phyllostomid Bat Occurrence in Successional Stages of Neotropical Dry Forests
Luis Daniel Avila-Cabadilla, Kathryn Elizabeth Stoner, Jafet M. Nassar, Mario M. Espírito-Santo, Mariana Yolotl Alvarez-A?orve, Carla I. Aranguren, Mickael Henry, José A. González-Carcacía, Luiz A. Dolabela Falc?o, Gerardo Arturo Sanchez-Azofeifa
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0084572
Abstract: Tropical dry forests (TDFs) are highly endangered tropical ecosystems being replaced by a complex mosaic of patches of different successional stages, agricultural fields and pasturelands. In this context, it is urgent to understand how taxa playing critical ecosystem roles respond to habitat modification. Because Phyllostomid bats provide important ecosystem services (e.g. facilitate gene flow among plant populations and promote forest regeneration), in this study we aimed to identify potential patterns on their response to TDF transformation in sites representing four different successional stages (initial, early, intermediate and late) in three Neotropical regions: México, Venezuela and Brazil. We evaluated bat occurrence at the species, ensemble (abundance) and assemblage level (species richness and composition, guild composition). We also evaluated how bat occurrence was modulated by the marked seasonality of TDFs. In general, we found high seasonal and regional specificities in phyllostomid occurrence, driven by specificities at species and guild levels. For example, highest frugivore abundance occurred in the early stage of the moistest TDF, while highest nectarivore abundance occurred in the same stage of the driest TDF. The high regional specificity of phyllostomid responses could arise from: (1) the distinctive environmental conditions of each region, (2) the specific behavior and ecological requirements of the regional bat species, (3) the composition, structure and phenological patterns of plant assemblages in the different stages, and (4) the regional landscape composition and configuration. We conclude that, in tropical seasonal environments, it is imperative to perform long-term studies considering seasonal variations in environmental conditions and plant phenology, as well as the role of landscape attributes. This approach will allow us to identify potential patterns in bat responses to habitat modification, which constitute an invaluable tool for not only bat biodiversity conservation but also for the conservation of the key ecological processes they provide.
Study of Duct Characteristics Deduced from Low Latitude Ground Observations of Day-Time Whistler at Jammu  [PDF]
M. Altaf, M. M. Ahmad
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.33032
Abstract:

Propagation characteristics of low latitude whistler duct characteristics have been investigated based on day-time measurements at Jammu. The morphogical characteristics of low latitude whistlers are discussed and compared with characteristics of middle and high latitude whistlers. The Max. electron density (Nm) at the height of the ionosphere obtained from whistler dispersion comes out to be higher than that of the background which is in accordance with the characteristics of whistler duct. The equivalent width is found to be close to the satellite observations and the characteristics of whistler duct in low latitude ionosphere are similar to those in middle and high latitude ionosphere. The width of ducts estimated from the diffuseness of the whistler track observed during magnetic storm is found to lie in the range of 50 - 200 Km.

Review Article: Immobilized Molecules Using Biomaterials and Nanobiotechnology  [PDF]
Magdy M. M. Elnashar
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2010, DOI: 10.4236/jbnb.2010.11008
Abstract: Immobilized molecules using biomaterials and nanobiotechnology is a very interesting topic that touching almost all aspects of our life. It uses the sciences of biology, chemistry, physics, materials engineering and computer science to develop instruments and products that are at the cutting edge of some of today’s most promising scientific frontiers. In this review article, the author based on his experience in this arena has tried to focus on some of the supports for im-mobilization; the most important molecules to be immobilized such as DNA, cells, enzymes, metals, polysaccharides, etc and their applications in medicine, food, drug, water treatment, energy and even in aerospace. He specified a special section on what is new in the arena of supports and technologies used in enzyme immobilization and finally a recommendation by the author for future work with a special attention to up-to-date references.
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