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Mixing aqueous silver solutions with aqueous leaf aromatic plant extracts from basil, mint, marjoram and peppermint resulted in the synthesis of quasi-spherical silver nanoparticles in a range of size between 2 and 80 nm in diameter as analyzed by analytical high-resolution electron microscopy. The average size could be controlled by applying heat to the initial reaction system at different rates of heating, and by the specific botanical species employed for the reaction. Increasing the rate of heating resulted in a statistically significant decrease in the size of the nanoparticles produced, regardless of the species employed. This fact was more evident in the case of marjoram, which decreased the average diameter from 27 nm at a slow rate of heating to 8 nm at a high rate of heating. With regard to the species, minimum sizes of

Candelilla (Euphorbia antisiphylitica Zucc.) is a very important plant resource in the arid lands of Northern Mexico. This is because the wax content coating the stem has unique properties which have been useful for multiple applications in the food industry, electronics, cosmetics, etc. However, the intensive exploitation of this resource has caused a great decrease in the populations of this species making necessary to consider strategies for their conservation and sustainable use. One of the primary needs with regeneration purposes is to know their reproductive processes, particularly the biotic and/or abiotic factors that determine the viability and germination of seeds. The present study evaluated the (1) germination and seed viability in relation to the ripeness degree of the fruit at the time of collection, (2) weight of the seed (low, medium and high), and (3) storage time (1, 3, and 5 months). Fruits from four locations, two in the State of Coahuila (Las Coloradas and Candela) and two in the State of Nuevo Leon (Icamole 1 and Icamole 2), were collected. Three germination assays were carried out corresponding to each month of storage. Seed viability was determined by the tetrazolium test. The average weight of the candelilla seeds was 0.0029 ± 0.0010 g, with extreme average values of 0.0018 ± 0.0006 g at Las Coloradas and 0.0036 ± 0.0010 g in Icamole 2. Those seeds with heavier weight obtained from red fruits and with 1 month of storage showed the highest average percentage of viability (66.87 ± 24.19%). At the same time, seeds with around average weight, obtained from red fruits and five months of storage, showed the highest average germination percentage (50.00 ± 9.42%).

ResumenEn el presente estudio se reconoció la diversidad polínica en el aire del área metropolitana de Monterrey (AMM), durante octubre 2004 a marzo del 2005. Se utilizaron 2 captadores volumétricos de polen (7 day recording volumetric spore trap, Burkard Manufacturing Co., Rickmansworth, Hersts., UK), situados en Ciudad Universitaria y La Florida. Se contabilizó un total de 7 687 granos correspondientes a 43 taxa para Ciudad Universitaria, mientras que para La Florida se registraron 12 354 granos correspondientes a 57 taxa. Los 10 taxa que presentaron la mayor concentración polínica durante el periodo de estudio fueron Cupressaceae/Taxodiaceae, Fraxinus sp., Quercus sp., Poaceae, Parietaria sp., Ambrosia sp., Populus sp., Salix sp., Pinus sp. y Celtis sp.AbstractThe occurring diversity of pollen grains in the air of the metropolitan area of Monterrey, Mexico was documented during the period October 2004 to March 2005 by means of 2 volumetric pollen grain collectors equipped with a 7 day recording volumetric spore trap (Burkard Manufacturing Co., Rickmansworth, Hersts., United Kingdom), one placed in the University City and the other at La Florida location. A total number of 7 687 pollen grains comprised in 43 taxa were counted at the University City while 12 354 grains were recorded among 57 recognized taxa in La Florida. The first 10 taxa with higher pollen concentration during the period of study were Cupressaceae/Taxodiaceae, Fraxinus sp., Quercus sp., Poaceae, Parietaria sp., Ambrosia sp., Populus sp., Salix sp., Pinus sp. and Celtis sp.

In order to eliminate magnesium from an A 380 Al-Si alloy at 750°C, the submerged powder injection method, using an inert carrier gas (Ar), was applied. The injected powders in the liquid aluminum bath were zeolite, silica and mixtures of zeolite-silica minerals. For each experiment the response variables were: eliminated magnesium versus injection time and quantity of drosses produced. Chemical analysis by atomic absorption spectrometry showed that mixtures of silica-zeolite 66:34 wt% have the best results with regarding to the removal magnesium from 1 to 0.0066 wt%. During the elimination of magnesium complex stoichiometry compounds were formed due to the reactions among zeolite, water steam and liquid aluminum. These compounds were analyzed by XRD, SEM and TEM. The results obtained, along with using the FactSage 6 thermodynamic software, allowed to elucidate the reaction mechanism between the minerals used and liquid aluminum.Se empleó el método de inyección sumergida de polvos por medio de un gas de arrastre inerte (Ar) con el fin de eliminar el magnesio de la aleación Al-Si A380 a 750 °C. Los polvos inyectados al baño de metal fundido fueron zeolita mineral, arena sílice y mezclas de ambas. Las variables de respuesta medidas fueron el contenido de magnesio en el baño metálico respecto al tiempo de inyección y las mermas de metal al final de cada experimento. En el análisis de resultados, la mezcla sílice:zeolita 66:34 % e.p. obtuvo la mayor eficiencia, lográndose una disminución en el contenido de magnesio en el baño metálico de 1 a 0.0066 % e.p. Los productos de reacción se analizaron por difracción de rayos-X, microscopía electrónica de barrido y de transmisión. Los resultados de estos análisis y el empleo del paquete termodinámico FactSage, versión 6, permitieron justificar el mecanismo de reacción entre los minerales y el aluminio líquido.

Newborn children of diabetic mothers have an increased morbidity and mortality because of respiratory distress syndrome. We study lung histogenesis during intrauterine development of offspring of diabetic Sprague-Dawley rats at 18, 19 and 21 days of gestation (DG). Pregnant rats were grouped into diabetic (streptozotocin-induced), citrate, and control groups; five female and five male offspring were selected randomly from each group at 18, 19 and 21 DG, and a biopsy of the lung was taken and processed in paraffin for histological examination. The biopsy for the transmission electron microscopy (TEM) analysis was taken at 21 days. A delay in alveolization of the offspring at 18, 19 and 21 days of the diabetic group was observed, which was confirmed at TEM level, and also less quantity of protein D associated to surfactant in diabetic group was detected (P < 0.001). The foetuses of the diabetic group presented a delay in lung histogenesis and in differentiation of the type II pneumocytes cells, but conserved the proportion with a decrease in 50% of pneumocytes, accompanied by a diminish of protein D associated to surfactant factor.

Leaf biomass over 20 native species from thornscrub canopies was evaluated by five non-destructive allometric methods and compared in order to determine the most accurate estimating procedure. Indirect relationships between leaf biomass and some ecological characteristics of the plants may be found by using regression models. Ecological and morphological characteristics of these species were determined using a structural analysis. No single standard method estimated leaf biomass for all species on site due to the diversity of geometric shapes in these species. However, Adelaide, double sampling and the dimensional methods were the most precise, practical and simplest methods for measuring the forage leaf biomass of many shrub species. The linear models gave a better estimate of tree biomass than the logarithmic functions. The regression equations showed a close relationship between foliar biomass and growth parameters.

Orchids of the genus Stanhopea are currently identified only by their floral structure characteristics. A statistical analysis of a sig- nificant number of species of this genus disclosed that measurements of adaxial and abaxial epidermal cell surface areas can be correlated with spe- cific recognized species by a leaf printing method. This allows an objective- ly either positive or nearly positive confirmation of the identity of a species in the absence of flowers and without damage to plants. When ordering the mean values obtained for these surface areas in each species in a decreas- ing order, a correlation was observed in a hierarchical way that went from primitive to more advanced floral forms. This reflects the evolutionary radi- ation of the genus. It is established that in Stanhopea, the presence of large leaf epidermal cells on species from South America represents a primitive evolutionary condition that became to smaller cells in evolutionarily more recent individuals as the genus radiated towards Mexico.

The coast of the Gulf of Mexico is characterized as a region with high variation in climatic conditions and rich in drought-tolerant or subhumid species. The species that are potentially useful for reforestation, regreening, agroforestry activities and the production of timber and fuelwood have been overexploited, resulting in a gradual decrease and degradation of their populations. In order to restore the soil and rehabilitate the disturbed areas inhabited by matorral vegetation, we tested the adaptability, development and establishment of 10 introduced tree species. The species were: Albizia caribaea Britton & Rose, Albizia guachapele (H.B. & K.) Dugand, Caesalpinia velutina (Britton & Rose) Standl., Caesalpinia eriostachys Benth., Crescentia alata H.B. & K., Enterolobium cyclocarpum Griseb., Gliricidia sepium (Jacq.) Steud., Haematoxylon brasilleto Karst., Myrospermum frutescens Jacq. and Pithecellobium dulce (Roxb.) Benth. The seeds of each species received different pretreatments. Seedlings were grown in plastic bags and planted out after 6 months by hand in August 1985 in a monoculture in four randomized blocks in a cleared area with deep loamy-clay soil, slightly alkaline. Measurements of different growth parameters and leaf/twig biomass over 15 years were evaluated. The species C. alata , E. cyclocarpum , G. sepium and H. brasilleto tended to have better characteristics in terms of growth annual rate (33–62 cm in height and 1.7–2.6 cm in basal diameter during 1985–1990), while A. caribaea , A. guachapele , C. velutina y C. eriostachys (20–30 cm in height and 1.2–1.7 cm in basal diameter) did not establish well due to susceptibility to frost. M. frutescens and P. dulce had intermediate yields of great interest due to their multipurpose potential. The linear models gave a better estimate of tree biomass than the logarithmic functions. The species with the highest determination coefficient ( r 2 ) and the lowest mean square error (MSE), were E. cyclocarpum ( r 2 = 0.96; MSE = 19.8), G. sepium ( r 2 = 0.99; MSE = 15.3), H. brasiletto ( r 2 = 0.95; MSE = 19.6) and M. frutescens ( r 2 = 0.98; MSE = 18.1). The regression equations showed the close relationship between stem diameter ( d n 2 ), stem length ( h ) and number of stems above ground level. The low mortality shown by the majority of the introduced species coupled with their high reproductive capacities suggests that these species may serve to enrich the matorral of the region, especially for silvicultural purposes.

Foroughbakhch, R., Dupraz, C., Hernandez-Pinero, J.L., Alvarado-Vazquez, M.A., Guzman Lucio, M.A. and Rocha Estrada, A. 2006. In vivo and in situ digestibility of dry matter and crude protein of honeylocust pods (Gleditsia triacanthos L.). J. Appl. Anim. Res., 30: 41–46. The aim of this study was to estimate the nutritional content, the rate of digestibility (in situ and in vivo) of nutrients contained in entire pods from four varieties of Gleditsia triacanthos L. Pods of each variety were hand harvested from natural vegetation around Montpellier, France. The in vivo and in sacco techniques were used to estimate degradability of dry matter (DM) and crude protein (CP) using a lot of castrated male Aries Merino sheep and rumen fistulated sheep. The mean daily ingestion value per animal varied between 57–80 g of the dry matter of pods/kg live weight0.75; the digestibility values varied considerably between individuals (44.7–71.9% of the DM). More than 55% of the DM of the pods was digested after an ...

The coast of the Gulf of Mexico is characterized by dry regions with a high variation in climatic conditions. This area is rich in drought-tolerant or subhumid species. In order to determine the most appropriate method in evaluating the leaf biomass of 15 shrubs species in a native matorral (thornscrub) of northeastern Mexico, a study was conducted to compare the following non-destructive methods: (1) Adelaide, (2) double sampling or dimensional analysis and (3) double sampling of branches. The non-destructive methods allow indirect relationships between leaf biomass and some ecological characteristics of the plants by using regression models. The methods were used to estimate leaf weight in each species. Ecological and morphological characteristics of these species were determined using a structural analysis. No single standard method estimated leaf biomass for all species on site, because of the diversity of forms in these species. However, Adelaide and the dimensional were the most precise, practical and simplest methods so they could be considered the method of choice for measuring the forage leaf biomass of many shrub species like Acacia rigidula Benth. (r2 = 0.98), Bernardia myricaefolia Wats. (r2 = 0.94), Caesalpinia mexicana A. Gray (r2 = 0.92), Leucophyllum frutescens (Berl) I.M. Johnst. (r2 = 0.95) y Zanthoxylum fagara (L.) Sarg. (r2 = 0.93), Celtis pallida Torr. (r2 = 0.99), Cordia boissieri A. DC. (r2 = 0.83), Parkinsonia aculeata L. (r2 = 0.83), among other species.

This work is devoted to microwave heating of graphite, sucrose, calcined sucrose, and a mixture of graphite with sucrose to produce carbon nanotubes (CNT's). The samples were submitted to microwave radiation (power 800W, frequency 2.45 GHz) in air and high vacuum (10−5Torr) for 30 – 60 min. The oven temperature was approximately 1200°C. After vaporization the condensed material was collected on various fused silica targets (different morphologies were used). The samples were found to contain a significant proportion of nanotubes, nanoparticles and fibers (1-2.8 micrometers), which appeared to be highly graphitized and helical structured. After deposition, the morphology of carbon nanotubes was studied with SEM, TEM and AFM techniques. It was observed that multi-walled nanotubes (MWNT's) were produced by this method. The morphology of fused silicon based substrates (SiO2, SiC) was studied as an important factor for the growth of carbon nanotubes. Many aspects as the size and shape of the obtained nanotubes on different substrates (porous and non-porous fused silicon substrates) were achieved, as well as the concentration of them across the substrate and other properties.