355 research outputs found
An assessment of apple varieties for their suitability in organic production systems
Twenty seven varieties of apple were assessed for their susceptibility to apple scab,
mildew and rosy apple aphid in a replicated experiment at East Malling Research. The
varieties most affected by mildew were Goldrush, DL11, Liberty, Bohemia and Pinova.
Ceeval, Discovery, Edward VII, Howgate Wonder, Rajka, Rebella and Topaz had the
lowest incidences of mildew. The highest incidence of scab occurred on Pilot and Pinova,
but infestation was low throughout the assessment period. In 2006 when aphid populations
were high, Liberty, Goldrush and Delorina had no aphid infestations, and low infestations
were seen on Edward VII, Resi and Santana
Electromagnetic properties of material coated surfaces
The electromagnetic properties of material coated conducting surfaces were investigated. The coating geometries consist of uniform layers over a planar surface, irregularly shaped formations near edges and randomly positioned, electrically small, irregularly shaped formations over a surface. Techniques to measure the scattered field and constitutive parameters from these geometries were studied. The significance of the scattered field from these geometries warrants further study
A study of the Scottish birch with special reference to the genetics and ecology of the species
Abstract Not Provided
Infrared multiphoton dissociation of two perfluorobutenes
Photofragment translational spectroscopy was used to examine the infrared multiphotondissociation of octafluoro-1-butene and octafluoro-2-butene. The predominant unimolecular reaction in octafluoro-1-butene at moderate laser fluences is cleavage of a carbon–carbon single bond to give the products CF3 and C3F5. The two other reactions that take place are CF2 elimination and the formation of equal weight fragments with the chemical compositionC2F4; both reactions take place via a diradical intermediate. Dissociation of octafluoro-1-butene to the resonance stabilized perfluoroallyl radical is suggested to account for the favoring of simple bond rupture. These three reaction pathways were also observed in octafluoro-2-butene dissociation, however, the branching fraction is different than from octafluoro-1-butene. In octafluoro-2-butene all three channels occur with roughly equal probability. The reactions involving CF2 loss and C2F4 formation in octafluoro-2-butene are thought to proceed through the same diradical intermediate as in octafluoro-1-butene, necessitating a 1,2-fluorine migration
Doped graphene nanohole arrays for flexible transparent conductors
Graphene nanohole arrays (GNAs) were fabricated using nanoimprint lithography. The improved optical transmittance of GNAs is primarily due to the reduced surface coverage of graphene from the nanohole fabrication. Importantly, the exposed edges of the nanoholes provided effective sites for chemical doping using thionyl chloride was shown to enhance the conductance by a factor of 15–18 in contrast to only 2-4 for unpatterned graphene. GNAs can provide a unique scheme for improving both optical transmittance and electrical conductivity of graphene-based transparent conductors
The response of perennial and temporary headwater stream invertebrate communities to hydrological extremes
The headwaters of karst rivers experience considerable hydrological variability, including spates and streambed drying. Extreme summer flooding on the River Lathkill (Derbyshire, UK) provided the opportunity to examine the invertebrate community response to unseasonal spate flows, flow recession and, at temporary sites, streambed drying. Invertebrates were sampled at sites with differing flow permanence regimes during and after the spates. Following streambed drying at temporary sites, dewatered surface sediments were investigated as a refugium for aquatic invertebrates. Experimental rehydration of these dewatered sediments was conducted to promote development of desiccation-tolerant life stages. At perennial sites, spate flows reduced invertebrate abundance and diversity, whilst at temporary sites, flow reactivation facilitated rapid colonisation of the surface channel by a limited number of invertebrate taxa. Following streambed drying, 38 taxa were recorded from the dewatered and rehydrated sediments, with Oligochaeta being the most abundant taxon and Chironomidae (Diptera) the most diverse. Experimental rehydration of dewatered sediments revealed the presence of additional taxa, including Stenophylax sp. (Trichoptera: Limnephilidae) and Nemoura sp. (Plecoptera: Nemouridae). The influence of flow permanence on invertebrate community composition was apparent despite the aseasonal high-magnitude flood events
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