38 research outputs found
Ethoxylation of fatty alcohols promoted by an aluminum alkoxide sulphate catalyst
No full textAluminum alkoxides are moderately active in promoting the ethoxylation of fatty alcohols. When these alkoxides are treated with pure sulfuric acid (100% by weight) in a stoichiometric ratio, the catalytic activity is strongly increased initially but it decreases rapidly giving place to products being very interesting for industry as they contain not more than two or three ethylene oxide adducts. These products are useful as raw materials for producing surfactants by sulphonation. Aluminum in the catalyst used shows all the possible coordination numbers, as demonstrated with the aid of 27Al NMR. The catalyst shows a very feeble Bronsted activity. As a consequence, small amounts of polyglycols are formed during reaction, in respect to the large amounts of ethoxylated dodecanol. Reaction rates are strongly inhibited by the presence of a Lewis base such as, for example, triphenylphosphine. The reaction seems to occur in the coordination sphere of the aluminum atoms. Other factors influencing activity and selectivity have been examined and a kinetic model has been developed on the basis of a reasonable reaction mechanism
Chain Propagation Rate Constants For Gas-phase Polymerization of Propene and 1-butene With Ziegler-natta Catalysts
No full textC-13 NMR analysis of propene/1-butene block copolymers obtained by gas-phase polymerization with Ziegler-Natta catalysts allows the determination of the propagation mte constants for the homopolymerization of the two monomers. They are very similar for the Solvay type catalyst delta-TiCl3/AlMe3 and the supported catalyst TiCl4/MgCl2/Phthalate/AlMe3. The constant of propene polymerization is three times higher than that of 1-butene polymerization. The high value of the constant found for propene polymerization is in agreement with the literature value determined by the stopped flow polymerization method
Zirconocene-based catalysts for the ethylene-styrene copolymerization: reactivity ratios and reaction mechanism
No full textA kinetic study of the ethylene-styrene copolymerization in the presence of rac-(ethylenebis- (1-indenyl)zirconium dichloride activated by MAO shows the peculiar behavior of this catalytic system that is known to produce crystalline nearly alternating copolymers. Some inferences on the monomer- metal interactions are made on the basis of this study. The parallel investigation on the catalyst based on isopropylidene(1-cyclopentadienyl)(9-fluorenyl)zirconium dichloride allows us to produce a stereoregular nearlyalternatingethylene-styrenecopolymeralsowiththiscatalyticsystem. Thesamemaintacticity seems to characterize the copolymers obtained with the C2 and Cs symmetric catalysts in accordance with the generally accepted mechanism of stereocontrol in the 1-alkene polymerizations
Diseño para la fusión de las canteras Agua Viva II y El Samán, considerando los planes de voladura a mediano plazo
No full textLa planificacion es un conjunto de estrategias a seguir para lograr una meta en un tiempo determinado, dentro de este concepto esta centrado este trabajo, en donde la base del problema es una fusion de dos canteras proyectada para un plan quinquenal, pero a traves de las distintas variables que acarrea una planificacion a 5 anos, como lo son las pistas, la carga, los ciclos de transporte, patrones de voladura entre otros factores que iran desarrollando a lo largo del trabajo. A partir de esto se tiene el objetivo Principal de este trabajo como lo es "Disenar la fusion de las Canteras Agua Viva II y El Saman, considerando los planes de voladura a mediano plazo.". Para ello se cuentan con diversas herramientas a utilizar, estas van desde tomar datos en campo hasta programas de dibujo asistido para los disenos finales, basicamente una metodologia sigue los siguientes pasos 1.- Reconocimiento de la Zona de Trabajo 2.- Recoleccion de Datos 3.- Estructuracion del Plan de Trabajo 4.- Diserio Computarizado De manera que la planificacion y estructuracion de trabajo fue llevada a cabo conjunto con el departamento de topografla, se proyecta una fusion de las canteras para los proximos 2 anos, siguiendo los planes de voladura y la planificacion de manera eficiente. Teniendo en cuenta diserio de rampas, pistas y nuevos frentes de trabajo. Sin embargo una de las grandes limitantes, y se podria decir que la mayor de todas es la falta de estudio geologico en la zona, por lo tanto se recomienda en la brevedad posible un plan de certificacion de reservas, que este dispuesto para unificar los lineamientos y realizar proyecciones certificadas de la vida util de la mina
Pest categorisation of Matsucoccus matsumurae
No full textThe EFSA Panel on Plant Health performed a pest categorisation of Matsucoccus matsumurae (Hemiptera: Matsucoccidae), the Massonian pine bast scale, for the EU territory. This pest categorisation was initiated following the commodity risk assessment of artificially dwarfed plants from China consisting of Pinus parviflora (Japanese white pine) grafted on P. thunbergii (Japanese black pine) performed by EFSA, in which M. matsumurae was identified as a pest of possible concern. However, its identity is not firmly established due to uncertainty regarding its taxonomic relationship with Matsucoccus pini (Green), a species widespread in Europe. M. matsumurae occurs in western China and has been reported as a pest of P. massoniana (Chinese red pine) and P. thunbergii. These hosts occur in the EU as ornamental/amenity trees. Other scales in the Matsucoccus genus feed on a variety of Pinus species and the host range of M. matsumurae could be wider than is currently recorded. The scale has one or two generations per year. All stages occur on the branches and stems of hosts with developing nymphs and adult females feeding through the bark on host phloem vessels. Symptoms include the yellowing/browning of host needles, early needle drop, desiccation of shoots and bark necrosis. The most serious infestations occur in hosts that are 8–25 years old and there can be some host mortality. In principle, host plants for planting and plant products such as cut branches and wood with bark could provide entry pathways into the EU. However, prohibitions on the import of Pinus from non-European third countries regulate these pathways. In China, M. matsumurae occurs in regions with temperate humid conditions and hot summers. These conditions are also found in parts of southern EU. Were M. matsumurae to establish in the EU, it is conceivable that it could expand its host range; however, this remains uncertain. Some uncertainty exists over the magnitude of potential impacts. M. matsumurae satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest, assuming M. pini is not a synonym, which is a key uncertainty
Pest categorisation of Malacosoma parallela
No full textThe EFSA Panel on Plant Health performed a pest categorisation of Malacosoma parallela (Staudinger) (Lepidoptera: Lasiocampidae) for the territory of the European Union, following commodity risk assessments of Berberis thunbergii, Malus domestica, Prunus persica and P. dulcis plants for planting from Türkiye, in which M. parallela came to attention as of possible concern. M. parallela is commonly known as the mountain ring silk moth and is a polyphagous leaf-eating pest in west-central Asia, primarily feeding on deciduous trees and shrubs, and known to cause serious damage to Malus, Prunus, and Quercus species. It is found at a range of altitudes from 130 m to 3000 m although most common above 1000 m. It is a univoltine species. Eggs are laid in masses on twigs and branches in the summer and larvae hatch the following spring to feed on buds and fresh leaves. Host plants can be completely defoliated. Plants for planting and cut branches provide pathways for entry, especially if infested with egg masses. Host availability and climate suitability suggest that parts of the EU would be suitable for establishment. Adults can fly and the pest could spread naturally within the EU although adults only live for a few days. Faster and more extensive spread is therefore more likely via egg masses moved on plants for planting. The introduction of M. parallela into the EU could lead to outbreaks causing damage to deciduous trees and shrubs in forests and orchards. Phytosanitary measures are available to inhibit the entry and spread of this species. M. parallela satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest
Pest categorisation of Mimela testaceipes
No full textThe EFSA Panel on Plant Health performed a pest categorisation of Mimela testaceipes (Coleoptera: Scarabaeidae), the striated chafer, for the EU, following a commodity risk assessment of dwarfed Pinus parviflora grafted onto P. thunbergii from China in which M. testaceipes was identified as a pest of possible concern to the EU. M. testaceipes occurs in Japan, northeast China, Far East Russia, South Korea and very likely North Korea. Adults are recognised pests feeding on and damaging the needles of Japanese cedar (Cryptomeria japonica), Japanese cypress (Chamaecyparis obtusa) and Japanese larch (Larix leptolepis) which are important forestry trees where the pest currently occurs. It has adapted to feed on the needles of Pinus species introduced into its native area, such as P. taeda, which is native to southeastern USA although M. testaceipes is not regarded as a significant pest of pines. Larvae are reported to cause root damage to grasses, as well as conifers. Eggs are usually laid in grassy soils by females that develop on conifer species. Larvae develop in the soil feeding on the roots of grasses or conifer hosts. Larvae overwinter in the soil and take 2 or 3 years to develop. In principle soil, host plants for planting and cut branches with foliage could provide pathways into the EU. However, prohibitions on the import of soil and hosts such as Chamaecyparis, Larix and Pinus regulate such pathways into the EU. Nevertheless, certain dwarfed Pinus spp. from Japan are provided with a derogation for entry into the EU. In addition, the host C. japonica is unregulated and could also provide a pathway. Hosts occur in the EU in climate zones that match those where M. testaceipes occurs in Asia. If M. testaceipes were to enter the EU, conditions in central and northern EU are conducive to establishment. Following establishment, impacts on Japanese cedar, Japanese cypress and Japanese larch would be expected; it is possible that M. testaceipes could adapt to feed on Pinus and Larix species growing in Europe. M. testaceipes satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest
Pest categorisation of Monema flavescens
No full textThe EFSA Panel on Plant Health performed a pest categorisation of Monema flavescens (Lepidoptera, Limacodidae), following the commodity risk assessment of Acer palmatum plants grafted on A. davidii from China, in which M. flavescens was identified as a pest of possible concern to the European Union. This species can be identified by morphological taxonomic keys and by barcoding. The adults of the overwintering generation emerge from late June to late August. The eggs are laid in groups on the underside of the host-plant leaves, on which the larvae feed throughout their six to eight larval instars. Pupation occurs in ovoid cocoons at the junction between twigs and branches, or on the trunk. Overwintering occurs as fully grown larvae or prepupae in their cocoon. There are one or two generations per year. M. flavescens is polyphagous and feeds on broadleaves; it has been reported on 51 plant species belonging to 24 families. It mainly occurs in Asia (Bhutan, China, the Democratic People's Republic of Korea, Japan, Nepal, the Republic of Korea), Russia (Eastern Siberia) and Taiwan. It is also present in the USA (Massachusetts). The pest's flight capacities are unknown. The main pathway for entry and spread is plants for planting with cocoons attached. This is partially closed by prohibition of some hosts. In several EU member states climatic conditions are conducive for establishment and many host plants are widespread. Introduction of M. flavescens may result in defoliations influencing tree health and forest diversity. The caterpillars also have urticating spines affecting human health. Phytosanitary measures are available to reduce the likelihood of entry, establishment and spread, and there is a definite potential for classical biological control. Recognising that natural enemies prevent M. flavescens being regarded as a pest in Asia, there is uncertainty regarding the magnitude of potential impact in EU depending on the influence of natural enemies. All criteria assessed by EFSA for consideration as a potential quarantine pest are met
Evaluacion del Escarificador MEQT-180X, con tres variedades de quinua (Chenopodium quinoa Willd) para reducir saponina y conservar lisina
No full textObjetivo: Determinar la eficiencia del equipo escarificador MEQT-180X, en la reducciOn del contenido de saponina y en la conservacion de lisina. Metodos: En el experimento diseriado se utilizo tres factores, variedad de quinua con tres niveles de factor: Pasankalla, Hualhuas y Amarillo Marangani, velocidad de rotacion: 500, 650 y 800 rpm y temperatura del aire de calentamiento: 100 °C, 150 °C y 200 °C. Para la conducciOn del experimento se utilizO un Diserio completamente aleatorio con arreglo factorial de 3x3x3. Resultados: Las variables respuesta consideradas fueron: contenido de saponina (%) y contenido de lisina (mg/g de quinua). El menor % de contenido de saponina se alcanzo utilizando la variedad de quinua pasankalla 0,1504±0,145, a una velocidad de rotaci6n del escarificador de 800 rpm y una temperatura de 200° C. el mayor % del contenido de saponina se dio en la variedad A. Marangani con el valor de 1,9476±0,524. Mientras que el mayor % del contenido de lisina se conservo utilizando la variedad de quinua Hualhuas, con el valor 54,2368±2,634 con velocidad de rotaciOn 500 rpm y 100 °C de temperatura. Conclusiones: Con el equipo escarificador MEQT-180X se logro determinar el minim° 6ptimo del contenido de saponina (%) en la quinua Pasankalla y la conservaciOn maxima del contenido de lisina (mg/g de quinua) en la variedad de quinua Hualhuas. Palabras clave: Quinua, quinua escarificada, escarificador, escarificado seco caliente
