Search

Las plantaciones de árboles de navidad con la especie Pseudotsuga menziesii (Mirb.) Franco ocupan 10% de la superficie total de este tipo de plantaciones en México. El tizón suizo es una enfermedad propia de del género Pseudotsuga, originada por el hongo Phaeocryptopus gaeumannii (T. Rohde) Petrak (1938). Los principales síntomas incluyen follaje clorótico y abscisión prematura de acículas infectadas, lo que resulta en copas ralas. El objetivo de este estudio fue determinar la relación entre la fertilización química y el estado nutrimental de los árboles con los niveles de severidad e incidencia de la enfermedad. La hipótesis fue que hay una correlación entre el estado nutrimental y la variación del grado de infestación del tizón suizo en P. menziesii. El estudio se estableció en el predio multifuncional “El Manantial” en Aquixtla, Puebla. Los tratamientos fueron fertilización con urea y sulfato de potasio y control fitosanitario químico con propiconazol y prochloraz. El diseño experimental fue bloques al azar generalizado, evaluando dos factores controlados con tres niveles (factorial 32) y como factor de confusión o bloqueo el nivel visual de transparencia de copa asociado al tizón suizo. La incidencia y la severidad se evaluaron. Los resultados del ANDEVA no indicaron diferencias significativas. De las variables nutrimentales las de mayor asociación a la severidad e incidencia fueron el contenido de Ca y Mn, y en menor medida, Cu, Mg y N. Entre los tratamientos se observaron antagonismos y sinergismos con efecto en el estado nutrimental. Los fungicidas influyen en la absorción, transporte y asimilación de los nutrimentos.

Metamorphic, igneous and sedimentary rocks, with low to no primary porosity, outcrop in the La Moza micro-basin stream (headwater of the Rio de Oro). In this high mountain system, water isotopic composition of rainwater, water isotopes and geochemistry of groundwater (springs) and surface water were determined. Groundwater flows are associated to phreatic aquifers in relationship with secondary porosity generated by fracturing, which is increased by dissolution processes in case of carbonate formation producing karstic systems and by the weathering phenomenon mainly affecting granodioritic rocks. Water geochemistry shows low to medium electrical conductivity (EC) depending on the geological formation, but a unique calcium bicarbonate facies. Spring water EC shows limited temporal variations. The isotopic composition of spring indicates a meteoric origin, local infiltration and groundwater flows with low residence time. A conceptual model of the recharge zone is proposed that crosses the surface watershed and covers part of the adjacent Rio Jordán basin, where the Berlin Paramo is located.

The majority of synthetic aromatic dyes are azo dyes (65-70 %), in which one or more N=N groups are linked to aromatic or heteroaromatic ring substituted with some functional groups. Azo dyes are mostly used in textile industry (80%), because of their low cost, high stability and colour variety, but also for colouring different substrates in many other industrial fields. Besides, they are used in a number of high-tech applications such as for optical data storage and non-linear optics [1, 2]. Compounds which contain heterocyclic ring, compared to those that have aromatic ring, are used in the design of new azo dyes due to the fact that they exhibit better colour strength and brightness. From variety of such dyes interest for those with benzothiazole ring is growing. We have previously reported synthesis and structural studies of several azo dyes that comprise benzothiazole ring [3, 4]. Herein we present the synthesis and X-ray structures of three novel benzothiazolyl azo derivatives that have potential to be used as textile disperse dyes. These derivatives differ in the substituent at 2-position of the benzothiazole ring (Fig. 1). The focus in this study is on conformation of the molecules and especially on their supramolecular assembling as it is known that small difference on surface of the molecule may significantly influence its supramolecular architecture. The results reveal that hydrogen-bonding in all structures is governed by two strong intermolecular hydrogen bonds, one O-H...N and one O-H...O. While both interactions in 1 form dimers, in 2 and 3 they link neighbouring molecules into infinite chains. Further difference in the supramolecular aggregation arise from a number of weaker C-H...O hydrogen bonds. Thus, two bifurcated C-H...O hydrogen bonds are present in 2 and 3, while only one is observed in 1. Interestingly, hydrogen-bonded dimers generated by O-H...N and O-H...O hydrogen bonds in 1 give rise to a parallel arrangement of aromatic rings and formation of Pi...Pi interactions (Fig. 2), which are completely absent in 2 and 3. All above mentioned interactions in these three structures are reinforced by C-H...Pi interactions, so forming three-dimensional networks. References: [1] Bamfield P. & Hutchings M. (2010). Chromic phenomena: Technological applications of colour chemistry, 3rd ed., Royal Society of Chemistry. [2] Samsami, S., Mohamadi, M., Sarrafzadeh, M.-H., Rene, E. R., Firoozbahr, M. (2020). Process Saf. Environ. Protect. 143, 138–163. [3] Pavlović, G., Racané, L., Čičak, H. & Tralić-Kulenović, V. (2009). Dyes Pigments 83, 354–362. [4] Racané, L., Mihalić, Z., Cerić, H., Popović J. & Tralić-Kulenović, V. (2013). Dyes Pigments 96, 672–678.

The selective coating is the heart of a solar heating system, where the coating needs to efficiently absorb sunlight and heat up the substrate, which subsequently transfers the generated heat to a fluid. Selective coatings generally have an IR reflecting interlayer that maintains low thermal emittance from the substrate in order to optimize the thermal efficiency of the collector. We report on the electrodeposition of a bright nickel/black nickel selective coating onto a copper solar collector substrate, and compare the optical properties and thermal stability with commercially available options, including copper oxide and sputter-deposited nitrogen-doped titanium dioxide. We have fabricated identical solar collectors of an aperture area of 1.74 m2 in order to compare the performance of the three selective coatings, and we have determined the thermal efficiency versus temperature difference in a realistic outdoor setting under sunlight. The collector with the electrodeposited selective coating shows overall better performance than the copper oxide-based collector, and at temperatures above about 50 °C, it achieves equal performance as the titanium dioxide-based collector. One of the reasons for the lower thermal losses for the electrodeposited collector appears to be the protection of the backside of the copper flat plates with a nickel coating. Taking the low investment and materials cost into account, the electrodeposited black nickel/bright nickel/copper flat-plate collector may be attractive for commercial implementation in solar water heaters.

Antecedentes: Los problemas para propagar C. pentadactylon por semilla se deben a su poca disponibilidad, bajo porcentaje de germinación, plagas y periodo juvenil mayor a 25 años.Hipótesis: Existe variación morfofisiológica de la semilla entre árboles y los tratamientos pregerminativos incrementan el porcentaje y la velocidad de germinación en semillas con seis meses de almacenamiento a temperatura ambiente . Especie en estudio: Chiranthodendron pentadactylon Larreat.Sitio de estudio y fechas: Colegio de Postgraduados, Campus Montecillo, Estado de México, Méx. Junio, 2016.Métodos: Se determinó el contenido de humedad, la viabilidad y el efecto de tratamientos pregerminativos en el porcentaje y velocidad de germinación de las semillas . Se utilizó un diseño de bloques al azar. Los bloques al azar con los tratamientos: 1 (escarificación mecánica + estratificación en frío a 5 °C durante 5 días), 2 (escarificación mecánica + imbibición durante 12 h), 3 (escarificación mecánica + corte en la base de la semilla) y 4 (testigo). Los tratamientos se aleatorizaron dentro de cada bloque.Resultados: El contenido de humedad fue menor a 10 % y la viabilidad de 100 %. Se encontraron diferencias significativas en la germinación entre tratamientos. La prueba de Tukey (? = 0.05) mostró diferencias entre los tratamientos pregerminativos 1, 2 y 3 con respecto al T4. La velocidad de germinación registró el mayor valor en el tratamiento 3.Conclusiones: Con los tratamientos 1, 2 o 3 se obtuvo más de 77 % germinación. El tratamiento 3 mostró mayor velocidad de germinación, lo que resulta importante en la producción de plántulas.

La fertilización en vivero es una práctica cultural con potencial para mejorar la calidad de planta, pero es necesario definir niveles de fertilización adecuados para cada especie. Este estudio evaluó el efecto de niveles de fertilización en la calidad de planta de Pithecellobium dulce, durante la etapa de vivero. Los niveles aplicados fueron nueve; consistieron en regímenes en los que se combinó un fertilizante de liberación controlada (FLC) 18-6-12, en tres dosis (4 g L-1, 6 g L-1 y 8 g L-1 de sustrato) con un fertilizante hidrosoluble (FHS) 20-20-20, en concentraciones de nitrógeno de 0 mg L-1, 75 mg L-1 y 150 mg L-1. El efecto de los regímenes de fertilización se determinó analizando índices morfológicos de calidad, tasas de asimilación neta (TAN) y estado nutrimental N-P-K en plantas de cuatro meses de edad. Una prueba de calidad fue diseñada para someter a las plantas a estrés en una condición de escasa fertilidad y pérdida de biomasa aérea, para evaluar capacidad de rebrote y crecimiento. Hubo diferencias estadísticas por efecto de los regímenes de fertilización. En general, la combinación de 8 g de FLC con 150 mg de nitrógeno por litro del FHS propició un incremento en la calidad morfológica y en la TAN de las plantas, aunque nutrimentalmente las respuestas principales fueron de suficiencia y dilución. En la prueba de calidad, las plantas tuvieron limitaciones para favorecer su rebrote o crecimiento según la cantidad de reservas nutrimentales. La fertilización con FLC y FHS tiene potencial para incrementar la calidad de planta de P. dulce en vivero.

Forests surrounding the Valley of Mexico are affected by air pollution produced within the valley; however, air pollution monitoring stations are scarce within the forest areas. This condition prevents the impacts of air pollution on forests from being studied. The aim of this study was to investigate the technical feasibility of using mathematical models to estimate O 3 and NO 2 concentrations in rural and suburban sites around the Valley of Mexico. Models for estimation of O 3 and NO 2 from data collected from the stations of the Red Automatica de Monitoreo Atmosferico (automatic air quality monitoring network, RAMA) and climatological variables from the Red de Meteorologia y Radiacion Solar (meteorology and solar radiation network, REDMET) of the Valley of Mexico were developed. We made 12 lineal multiple regression models for estimating air pollutants for stations Ajusco Medio, Cuajimalpa, Cuautitlan, and Montecillo. Estimations of O 3 are a function of O 3 concentrations and/or concentrations of NO 2 , O 3 , and meteorological variables from RAMA and REDMET. Models for NO 2 estimate this pollutant as a function of concentrations of NO 2 and meteorological variables. The best models for estimating O 3 are those that depend on O 3 concentrations from other stations, being temperature, relative humidity, and wind velocity the meteorological variables that impacted O 3 estimations the most. Models for NO 2 concentrations behaved correctly, except that of Cuautitlan. Temperature and wind direction are the variables that impacted NO 2 concentrations the most.

Objetivo: determinar los sistemas bioproductivos en Xaltepuxtla, Puebla, México, e identificar limitantes y potencialidades para incidir en proyectos detonadores de cambio que favorezcan la biodiversidad, capacidad productiva y economía familiar. Diseño / metodología / aproximación: a partir de la construcción de un Sistema de Información Geográfica se analizó la información biofísica y del taller participativo, corroborándose con recorridos de campo en las diferentes unidades bioproductivas. Esta metodología corresponde a la primera fase para la propuesta del Ordenamiento Territorial Comunitario (OTC). Resultados: el 49% de la superficie en estudio se dedica a la producción de ornamentales, el 22% de la superficie a la restauración del BMM y el 8% tiene potencial para la tecnología agroforestal: enriquecimiento de acahuales. Se identificaron 35 sistemas bioproductivos. El sistema con mayor superficie es el destinado a la reforestación con 8 hectáreas, seguido del Bosque Mesófilo de Montaña secundario ubicado en aparato volcánico con 7.5 ha, y del Sistema Mixto de Ornamentales en laderas escarpadas con 5.5 ha. Limitaciones / implicaciones: la delimitación de las unidades bioproductivas a partir del mapeo de geoformas, uso de suelo y vegetación y clima son clave para la regionalización del territorio y la generación de propuestas de reconversión productiva a nivel finca. Hallazgos/ conclusiones: es de vital importancia ubicar los sistemas bioproductivos dentro de un territorio para lograr el proceso de planificación de los usos de suelo en relación con los recursos naturales, su población y actividad productiva a fin de lograr el equilibrio productivo y la conservación en el mediano y largo plazo.

The development of elastomeric, bioresorbable, and biocompatible segmented polyurethanes (SPUs) for use in tissue-engineering applications has attracted considerable interest in recent years because of the existing need for mechanically tunable scaffolds for regeneration of different tissues. In this study segmented polyurethanes were synthesized from poly(e-caprolactone)diol, 4,4′-methylene bis(cyclohexyl isocyanate) (HMDI) using osteogenic compounds such as ascorbic acid (AA) and L-glutamine (GL) as chain extenders, which are known to play a role in osteoblast proliferation and collagen synthesis. Fourier transform infrared spectroscopy (FTIR) revealed the formation of urethane linkages at 3373, 1729, and 1522 cm−1 (N–H stretching, CO stretching and N–H bending + C–N stretching vibrations, respectively) while urea formation was confirmed by the appearance of a peak at 1632 cm−1. Differential scanning calorimetry, dynamic mechanical analysis, X-ray diffraction and mechanical testing of the polyurethanes showed that these polyurethanes were semi-crystalline polymers (Tg = −25 °C; Tm = 51.4–53.8 °C; 2θ = 21.3° and 23.4°) exhibiting elastomeric behavior (e > 1000%) only for those prepared by HA incorporation during prepolymer formation. Dense and porous composite matrices of the segmented polyurethanes were prepared by the addition of hydroxyapatite (HA) via either mechanical mixing or in situ polymerization and supercritical fluid processing, respectively. The addition of HA by physical mixing decreased the crystallinity (from 38% to 31%) of the composites prepared with ascorbic acid as the chain extender. Both Tg of the composites and the strain were also lowered to −38 or 36 °C and 27–39% for ascorbic acid and glutamine containing polyurethanes respectively. Composites prepared with ascorbic acid as the chain extender yielded higher Young's modulus and tensile strength than composites prepared with glutamine when HA was incorporated during prepolymer formation. Composites obtained by incorporation of HA by physical mixing revealed a poor dispersion in comparison to composites obtained via HA inclusion during prepolymer formation. In contrast, good dispersion of HA and porosity were achieved at 60 °C, 400 bar and holding times between 0.5 h and 2 h with a downtime between 15 min and 60 min in the CO2 reactor. Biocompatibility studies showed that SPUs containing ascorbic acid allowed the increase of alveolar osteoblast proliferation; hence, they are potentially suitable for bone tissue regeneration.

Background. All of the Pinaceae require the ectomycorrhizal interaction to survive under field conditions. However, their use has not traditionally been considered in the production of forest plants in Neotropical areas. Hypothesis. There will be an increase in plant quality in greenhouse and in survival in the field of Pinus pringlei inoculated with ectomycorrhizal fungi (ECMF). Site of study. The experiment was carried out in Texcoco, Mexico, in two sites: i) greenhouse of the Colegio de Postgraduados; and ii) in the field, in the San Pablo Ixayoc town. Methods. P. pringlei plants, a native species of Mexico, were inoculated with the ECMF: i) Hebeloma alpinum ( Ha ); ii) Laccaria trichodermophora ( Lt ); and iii) Thelephora terrestris ( Tt ). The effect of this inoculation on plant growth and nutritient translocation was evaluated. A morphological and molecular characterization of ectomycorrhizal roots and an evaluation of the seedling field survival were carried out, and compared with non-inoculated plants. Results. Pinus pringlei plants inoculated with ECMF increased their growth and nutrient content. A significant nutritional allocation from root to stem mainly of K, Fe, and Zn was recorded. The morpho-anatomical and molecular characterization showed the presence of Ha , Lt and Tt in ectomycorrhizal roots. Two-year old plants mainly inoculated with Ha and Tt showed higher survival in the field than non-inoculated plants. Conclusions. The beneficial effects of ECMF on P. pringlei growth, nutrimental translocation (mainly on K, Fe and Zn), and field survival rates are reported for the first time.

Solar absorber coatings are the heart of solar-thermal power systems and their desired properties intimately depend on the operational temperature. Specifically for medium to high temperature applications, the systems require a thermally-stable selective coating with optimal optical properties. Black metal mixed oxides with the spinel crystal structure are interesting prospects as a new family of selective absorber materials. In this work we report on the indirect electrodeposition of a spinel black oxide of the type MnxCo3-xO4, using a nitrate solution; the electrochemical reduction of nitrate results in the formation of surface hydroxide leading to the co-precipitation of Co and Mn hydroxides, and the resulting mainly amorphous film is subsequently converted to the spinel material by sintering. The optimal precursor chemistry and electrodeposition conditions were obtained using a combinatorial method employing the Hull cell. After optimization and thermal annealing, spinel MnxCo3-xO4 films (x ≈ 0.7) with solar absorptance of α = 89.5% and thermal emittance of e = 14.9% (at 100 °C) were obtained, illustrating their promising optical properties. The thermal stability of the coatings at medium and high temperatures (250 °C and 560 °C), as well as under harsh accelerated weathering conditions, was found to be excellent. The scalability of the electrodeposition method was confirmed by deposition onto a stainless steel tube.

Traditionally, it is thought that arbuscular mycorrhizae establish a symbiosis with the roots of numerous angiosperm and some gymnosperm families. However, the mobilization and transfer of macro- and micronutrients to Pinaceae via arbuscular mycorrhizal fungi (AMF) has not been reported so far. The present work evaluated whether arbuscular mycorrhizae are able to establish, mobilize, and transfer nutrients in the neotropical species of Pinaceae, Pinus greggii . Seedlings were inoculated with 3 AMF consortia isolated from an agricultural site, a Cupressus lusitanica forest and a Pinus hartwegii forest. Evidence of mobilization and transfer of macro- and micronutrients in plants inoculated with the 3 consortia was evaluated. A greater Mg, Mn, and Zn mobilization and transfer was observed in plants inoculated with the pine forest AMF consortium after 7 months. In addition to these positive effects, AMF root colonization of 10 to 15% and 21 to 36% was observed depending on the AMF consortia after 2 and 7 months. In the present work, we report for the first time that AMF mobilize and transfer N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, and B to a member of Pinaceae, indicating that this mycorrhizal symbiosis is more complex than previously believed.

Production of forest seedlings is expensive mainly due to the use of inputs such as peat moss and fertilizers. Seedling survival in field conditions is low when seedlings with limited internal nutrient reserves are used in low fertility sites. In this work, raw sawdust and exponential fertilization were tested against peat-moss and constant fertilization, the common components of containerized seedling production systems in Mexico. The experiment was carried out under nursery conditions by using a complete randomized experimental design with a 2×2 factorial arrangement. Two substrates   peat-moss (PM) and sawdust (SA)   and two nutrient addition rates   constant (CR) and exponential (ER)   were tested. The response of seedlings was assessed based on diameter at the root collar, seedling height, dry weight (shoot, root, total and 100-needle), Dickson quality index (DQI), slenderness index (SI), and foliar nutrient concentrations and contents. Analysis of variance indicated that the substrate significantly affect all dry weights, with the greatest biomass observed for PM. Similarly, DQI and SI were affected by the substrate, with PM showing the best DQI and highest SI. Neither plant quality variables nor dry weights were affected by nutrient addition rates. Both substrate and nutrient addition rate significantly affected N, P, and K foliar concentrations. At the end of the production cycle, SA promoted higher foliar concentrations of N and P than PM, but not those of K. This suggests that K limited the growth of seedlings in sawdust, likely due to the low capacity of this substrate to adsorb K. ER produced needle concentrations of N, P, and K significantly higher than those of CR (2.65 vs. 2.26 %, 2303 vs. 2011 ppm, and 4235 vs. 3949 ppm, respectively). Our results indicate that ER is likely to give rise to more suited seedlings for outplanting in low fertility sites than CR.

En México, la producción de plantas forestales en contenedores rígidos se realiza utilizando principalmente como medio de crecimiento la turba, la vermiculita y la agrolita (6:3:1, mezcla estándar). El aserrín y la corteza de pino son desechos de la industria forestal que pueden ser usados como sustratos. Este trabajo tuvo como objetivo caracterizar cinco mezclas de sustratos, compuestos de corteza, aserrín, turba, vermiculita y agrolita. La evaluación de las mezclas incluyó la caracterización física (densidad aparente, porosidad y curva de retención de humedad) y química (pH, conductividad eléctrica y capacidad de intercambio catiónico). La densidad aparente de las mezclas compuestas de corteza y aserrín varió de 0,31 a 0,51 g cm- 3 y la estándar fue de 0,15 g cm- 3. La porosidad total de 77% a 91% y la estándar fue de 84%. La porosidad de aireación varió de 8% a 20% y la estándar fue de 8%. El agua fácilmente disponible varió de 4,8% a 9,9% y la estándar presentó un valor más elevado (17,7%). El pH de las mezclas compuestas de corteza y aserrín varió de 4,52 a 7,70 y la estándar fue de 3,87. La conductividad eléctrica de 1,84 a 2,69 ds m- 1 y la estándar 1,13 ds m- 1. La capacidad de intercambio catiónico de 43,6 a 89,4 meq/100 g y la estándar 60,4 meq/100 g. La mezcla 4 (20% de corteza + 80% de aserrín) es semejante a la mezcla estándar por sus características físicas, pero no en sus propiedades químicas. Esta mezcla es un sustrato prometedor en la producción de plantas forestales.

There are two properties shared by all known crossing-minimizing geometric drawings of K"n, for n a multiple of 3. First, the underlying n-point set of these drawings minimizes the number of (@?k)-edges, that means, has exactly 3(k+22)(@?k)-edges, for all 0@?k

The objective of this study was to identify salinity tolerant avocado materials useful as rootstocks. Embryonic axes of Creole avocado and 'Hass' in Murashige and Skoog medium were seeded in 100% of their nutritional composition under salt conditions induced with NaCl and CaCl2. Five levels of each salt (0.1, 0.3, 0.5, 0.7, 0.9%) were used, as well as the combination of these in a 1: 1 ratio. Germination, emergence, rooting and survival of avocado shoots were studied. Creole outperformed Hass with 21% germination, 36% emergence, with approximately 50% in each of the growth variables and 10% of seedling survival. The development of embryonic axes was more limited in NaCl treatments compared to those established in CaCl2 and NaCl: CaCl2. With the in vitro technique, it was determined at 65 days of culture that the creole material was more tolerant to saline stress than to Hass.

An ectomycorrhiza is a mutualistic symbiosis of paramount importance in forestry and tree production. One of the selection criteria of ectomycorrhizal fungi that has currently gained importance is their edibility due to the economic, ecological and cultural relevance of edible ectomycorrhizal mushrooms as a non-timber forest product. The effect of the inoculation with three edible ectomycorrhizal mushrooms: Laccaria laccata, Laccaria bicolor y Hebeloma leucosarx, which are widely sold in Mexico, on the growth and nutrient contents of Pinus greggii grown in an experimental substrate and a commercial substrate enriched with a slow-release fertilizer, was evaluated. Two years after sowing, differences in terms of shoot and root biomass and macro and micronutrient contents between inoculated and non-inoculated plants, were recorded independently of the fungal species and the substrate. Despite the fact that plants grown in the commercial substrate had higher growth and nutrient contents, their ectomycorrhizal colonization percentages were smaller than those of the plants grown in the experimental substrate. The differences in the nutrient transfer to the inoculated plant shoots among the evaluated fungal species were recorded. Ca mobilization by L. laccata, Na by L. bicolor and Mn by H. leucosarx were observed in the plants growing in the experimental substrate. It has been demonstrated that the selection of substrates constitutes an important factor in the production of ectomycorrhizal plants and that the three evaluated species of edible ectomycorrhizal mushrooms have an enormous potential in the controlled mycorrhization of P. greggii.

Plantas obtenidas mediante micropropagación de las especies: Eucalyptus urophylla y Eucalyptus grandis, que medían de 3 a 7 cm. de longitud y poseían como mínimo 3 raíces, se colocaron en bolsas con suelo arcillo arenoso como sustrato y fueron ubicadas en un vivero que proporcionaba 70 % de sombra. El riego fue por aspersión durante 15 días, se fertilizaron a los 25 días de iniciada la aclimatación y se realizaron aspersiones con Oxicloruro de Cobre cada 7 días. A los dos meses de haber sido trasplantadas a suelo, las plantas alcanzaron aproximadamente 20 cm de longitud y se consideraron preparadas para plantación. Los porcentajes de adaptación logrados fueron: E. urophylla 85 % y E. grandis 75 %.

Cedrela odorata es una de las especies nativas de mayor importancia forestal en México; sin embargo, el desarrollo de plantaciones se ha visto limitado por la presencia del barrenador de las meliáceas. La búsqueda de alternativas para erradicar o controlar la plaga continúa siendo preponderante. En el presente, se analiza la factibilidad del manejo nutrimental a través de fertilización como método contra esta problemática. Para ello, en una plantación de cedro rojo ubicada en Papantla, Veracruz, mediante un experimento factorial se evaluaron los efectos de la aplicación de nitrógeno, fósforo y potasio, sobre el crecimiento de C. odorata e incidencia de Hypsipyla grandella. Durante un año, se realizaron evaluaciones periódicas en campo de crecimiento en altura y diámetro, y de otras variables relacionadas con la incidencia de la plaga. Existieron respuestas positivas en el crecimiento mediante la aplicación de nitrógeno y se manifestó una reducción del ataque con el suministro del potasio, pero en general estas fueron limitadas debido a diversas condiciones de la plantación. A pesar de esto, la fertilización mostró potencial como método de control de la incidencia de H. grandella en plantaciones de C. odorata.

La declinación forestal en el Desierto de los Leones, D. F. afecta a Abies religiosa, una de las especies dominantes en la región con difícil capacidad de enraizamiento que requiere propagación en la zona. En el presente estudio se desarrolló un método de propagación vegetativa con el fin de determinar si el efecto de la procedencia, edad del material, tipo de hormona y la presencia de síntomas de declinación, influyen en la capacidad de enraizamiento de estacas de dicha especie. En este experimento se utilizó un sustrato compuesto por turba y agrolita para probar estacas de dos procedencias, con y sin síntomas de declinación, generadas en dos estaciones de crecimiento, y dos auxinas, manteniendo una humedad de 75-80 %. La combinación de estos factores produjo 16 tratamientos, los cuales se repitieron 50 veces. Los datos fueron procesados mediante un análisis de varianza factorial. Los resultados indican que a principios de diciembre es la mejor época de recolecta de material vegetal para enraizamiento de estacas de A. religiosa, siendo las estacas más jóvenes y las que recibieron indol-3-butírico las que mejor enraizaron. La procedencia y la sintomatología no tuvieron efecto en el enraizamiento.

In this study, we evaluated the usefulness of biorelevant in vitro data and of canine data in forecasting early exposure after the administration of two phases of a BCS Class II compound, i.e., doxazosin base (DB) and its mesylate salt (DM). DB, DM, and doxazosin hydrochloride (DH) were prepared and characterized. In vitro data were collected in various media, including human aspirates. Solubilities of DB and DM in human gastric fluid were forecasted by data in fasted state simulating gastric fluid containing physiological components (FaSSGF-V2) but not by data in HCl pH 1.8. Unlike data in FaSSGF-V2, dissolution of DB and DM tablets in HCl pH 1.6 is rapid. Dissolution of DB tablet in FaSSGF-V2 is incomplete and conversion to DH seems to occur. Differences between DB and DM in dissolution in the small intestine are overestimated in the absence of physiological solubilizers. Using the in vitro data and previously described modeling procedures, the cumulative doxazosin profile in plasma was simulated and the 0-2 h profile was used for evaluating early exposure. Individual cumulative doxazosin profiles in plasma, after single DM tablet administrations to 24 adults, were constructed from corresponding actual plasma profiles. Compared with in vitro DM data in pure aqueous buffers, DM data in biorelevant media led to better prediction of early exposure. Based on intersubject variability in early exposure after DM administration and simulated profiles, the administered phase, DB or DM, does not have a significant impact on early exposure. Partial AUCs were used for evaluating early exposure after DB and DM administration in 4 dogs. Early exposure was significantly higher after administration of DM to dogs. Dogs are not appropriate for evaluating differences in early exposure after DB and DM administrations. © 2011 Elsevier B.V. All rights reserved.

We demonstrate an ultraviolet diode laser system for cooling of trapped ytterbium ions. The laser power and linewidth are comparable to previous systems based on resonant frequency doubling, but the system is simpler, more robust, and less expensive. We use the laser system to cool small numbers of ytterbium ions confined in a linear Paul trap. From the observed spectra, we deduce final temperatures < 270 mK., submitted to Opt. Lett

The objective of this study was to identify the factors controlling the arrival of amlodipine into the systemic circulation after oral administration in the fasting state. Dissolution data were collected with the rotating paddle and the flow-through apparatus. Caco-2 cell lines were used to assess the intestinal permeability characteristics. Actual in-vivo data were collected in 24 fasted healthy subjects after single-dose administration of the same amlodipine besylate tablet formulation used in the in-vitro dissolution studies. Regardless of the hydrodynamics, dissolution of amlodipine besylate tablets was rapid and complete in media simulating the contents of the upper gastrointestinal tract in the fasting state. Permeability of amlodipine through Caco-2 cell lines was lower than propranolol's and higher than ranitidine's, indicating that transport through the intestinal mucosa may be one process that limits the arrival into the systemic circulation. Indeed, the deconvoluted profile indicated that arrival into portal blood occurs at rates much slower than gastric emptying or dissolution rates. However, prediction of amlodipine's mean plasma profile after oral administration became possible only after additionally assuming excretion of amlodipine into the bile and a reasonable gastrointestinal residence time. Interestingly, in-vitro permeability data collected in this or in previous studies were inappropriate for simulating the mean actual plasma profile. © 2006 The Authors.

El consumo mundial de madera se reparte entre las necesidades energéticas, leña y carbón vegetal (más del 50 %), la madera de aserrío, postes, apeas y construcción (20 %) y la dedicada a la industria de la celulosa y el papel (27 %). Las previsiones mundiales para el consumo de madera en el año 2000 superan los 4 000 millones de m3, lo que supone un déficit de 1 000 millones. En el mundo hay un déficit tanto de madera como de energía, lo que convierte a la producción forestal en un objetivo prioritario. El género Eucalyptus ha sido y es uno de los recursos forestales más utilizado industrialmente en el mundo entero. Originarios de Australia, presentan una enorme diversidad, con más de 600 especies diferentes. Su madera resulta adecuada para muy diversos usos: consumo doméstico, leñas de alto poder calorífico, producción de carbón vegetal, estructuras de edificios, postes para comunicaciones, suelos de parquet, pasta celulósica, apeas de mina, sujeción de taludes, o para elaboración de tableros de fibras. De su celulosa pueden fabricarse múltiples productos de uso cotidiano: sanitarios, pañales e higiénicos; derivados como el celofán o la cola de empapelar; fórmica y otros laminados, papeles especiales, filtros, papeles electrónicos; así como elaboración de fibras textiles como el rayón. La demanda de productos derivados de la madera de eucalipto sigue siendo, a nivel internacional, la que muestra un mayor crecimiento sostenido.

El árbol de eucalipto (E. urophylla y E. grandis) es un recurso importante, debido a su aprovechamiento industrial en la obtención de celulosa y hemicelulosa para la fabricación de papel en varias partes del mundo en general y en particular en el sureste de México. Varios alcances biotecnológicos han sido desarrollados para solucionar las dificultades de variabilidad genética en propagación por semilla que presentan las especies de eucalipto. Para ello, resulta necesario el estudio de diversas estrategias de micropropagación que permitan la obtención y multiplicación de clones de eucalipto. Por lo que el objetivo de este trabajo fue establecer la tecnología para la micropropagación clonal in vitro de genotipos seleccionados, con el fin de obtener plantas de alta calidad destinadas a las plantaciones o a huertos clonales en el sureste de México. Para el establecimiento de los explantes a condiciones in vitro se evaluaron tiempos de desinfestación de los explantes, realizando la combinación de tres niveles de desinfección con antibiótico (terramicina 40 mg/l00 ml) y con fungicida (cuprimicin 150 mg/100 ml) a 0, 10 y 30 minutos. Obteniéndose hasta un 90 % de cultivos libres de contaminación. Además se evaluó la multiplicación de brotes, la formación de callo y enraizamiento para ambas especies, combinando tres niveles de benziladenina (0.0, 1.0 y 3.0 mg L-1) y de ácido naftalen acético (0.0, 1.0 y 3.0 mg L-1) en un medio de cultivo Gamborg B5. Se obtuvo hasta 9 brotes por explante cultivados y una media de 5.5 raíces por explante, combinando 3 mg L-1 de benziladenina y 1.0 y 3.0 mg L-1 de ácido naftalen acético. Los protocolos para aclimatación de plantas fueron también establecidos.

The nutrient status of forest soils in the Mexico City Air Basin was evaluated by observing plant growth responses to fertilization with N, P or both nutrients combined. P deficiency was the most frequent condition for soil from two high pollution sites and N deficiency was greatest at a low N deposition site. Concentrations of Pb and Ni, and to a lesser extent Zn and Co, were higher at the high pollution sites. However, positive plant growth responses to P and sometimes to N, and results of wheat root elongation bioassays, suggest that heavy metal concentrations were not directly phytotoxic. Further studies are needed to determine if heavy metal toxicity to mycorrhizal symbionts of eucalyptus (Eucalyptus camaldulensis Dehnh.) from high pollution sites may explain the P deficiency and stunted growth. P deficiency is expected to limit the capacity for biotic N retention in N saturated forested watersheds in the Basin of Mexico dominated by Andisols.

Con el objetivo de evaluar el potencial de Pinus greggii Engelm. para almacenar carbono en la biomasa aérea, se estimó la biomasa total aérea en una muestra de 20 árboles, los cuales se separaron en tallo, ramas y follaje. El estudio se llevó a cabo en una plantación de seis años de edad establecida en Cuaunepantla, Acaxochitlán, Estado de Hidalgo, México. La biomasa seca aérea promedio fue de 8.0 kg por árbol, de la cual 4.1 kg (51 %) se ubicó en tallo, 1.9 kg (24 %) en ramas y 2.0 kg (25 %) en follaje. La productividad primaria neta fue estimada en 5.8 t ha-1 año-1, para una densidad de 4425 árboles/ha. La concentración de carbono en tejido vegetal fue de 51 %. Una ecuación matemática sencilla (y = 147x + 3288x2) para estimar la biomasa de carbono a partir de la variable combinada de diámetro y altura (D2h) explicó 89 % de la variación. Estos resultados muestran que el potencial de almacenamiento de carbono en una plantación de seis años de P. greggii Engelm. es relativamente alto, con 17.9 t ha-1, que representa una masa de dióxido de carbono equivalente de 65.8 t CO2 ha-1.

The applicability of the modofied fluorometric method for the determination of thiamine and its phosphate esters in food for the determination of thiamine-chloride-hydrochloride in multivitamine preparations was investigated. The method is based on alkaline oxidation of thiamine to highly fluorescent thiochrome. The procedure gives satisfactory recovery (87.81 %-100.54%) and a relative standard deviation of parallel determination range between 1.87% and 8.16% (meaqn 4.51%). The acceptability of the method was evaluated after criteria suggested by the Analytical Reference Servis. The total error of discrete determination of thiamine-chloride-hydrochloride ranged between 8.78% and 21.47% (mean 15.95°%), so the proposed simple, rapid and easy to perform procedure is rated an excellent method and acceptable for determination of thiamine-chloride-hydrochloride in control of multivitamin preparations. Deviation of determined thiamine-chloride-hydrochloride content from declarative on the investigated pharmaceutical products ranged from -12.99% to +0.55% and are in agreement with the limits regulated by Pharm. (+- 15%).

U okviru širih istraživanja prehrambene i biološke vrijednosti samoniklog jestivog, začinskog i ljekovitog bilja koje raste u našim krajevima, određen je standardnim fizikalno-kemijskim metodama sadržaj dušićnih spojeva , lipida, ugljikohidrata i vitamina u biljkama omaga (Salicornia herbacea L.), matar (Crithmum maritimum L.), komorač (Foeniculum vulgare Mill), kostriš (Sonchus oleraceus L.) i crni sljez (Malva silvestris L.), s otoka Lošinja. Sadržaj vlage ovisno o vrsti biljke kreće se od 72.81 % do 87.95 %. U 100 g svježeg uzorka sadržaj dušićnih spojeva određenih kao sirovi proteini kreće se od 1.53 g do 4.60 g, masti od 0.28 g do 0.71 g, ukupnih šećera od 0.50 g do 1.54 g, a sirove celuloze od 1.95 g do 4.85 g. Ovisno o ispitivanom vitaminu (tiamin, riboflavin, niacin, karoten) sadržaj se kreće od 0.07 mg do 6.53 mg. Analizom rezultata ustanovljeno je da se ispitivano samoniklo bilje prema sadržaju ovih sastojaka može usporediti s kultiviranim povrćem i da ga u odnosu na njegovu hranjivu vrijednost može uspješno zamijeniti.

U praksi se za određivanje ostataka slobodnog formaldehida u zaštitnim lakovima za metalnu ambalažu koriste najčešće dvije fotometrijske metode, metoda sa kromotropnom kiselinom i metoda sa acetil-acetonom (Franck, 1987). Kako u reakciji formaldehida i kromotropne kiseline interferiraju fenoli, testirana je primjenjivost ovih dviju metoda za određivanje malih količina slobodnog formaldehida u iscrpinama lakova u kojima su identificirani fenoli u tragovima, te ocjenjena zdravstvena ispravnost ispitivanih lakova. Ispitana je migracija formaldehida iz tri vrste zaštitnih lakova epoksid-esterskog tipa metalne ambalaže za mesne proizvode sa i bez povrća. Sadržaj formaldehida određen je u isrpinama s model otopinama (destilirana voda i model otopina simulans - 2% NaCl u 3% CH3COOH). Zbog interferencije sa fenolima metodom sa kromotropnom kiselinom dobivene su znatno veće vrijednosti sadržaja formaldehida (2-8 puta) u odnosu na sadržaj određen metodom sa acetil-acetonom, pa se kao metoda izbora za određivanje niskih koncentracija formaldehida u isrpinama lakova koji sadrže fenole u tragovima preporuča metoda sa acetil-acetonom. Sadržaj formaldehida u iscrpinama određen kromotropnom kiselinom kretao se od 0.088-0.0112 mg/dm2, a određen acetil-acetonom 0.011-0.063 mg/dm2 što je znatno ispod maksimalno dozvoljene kooncentracije (0.5 mg/dm2 površine laka) propisane "Pravilnikom o uvjetima zdravstvene ispravnosti predmeta opće uporabe koji se mogu stavljati u promet" (NN 46/94).