992 resultados para Synthetic images
Resumo:
Self-affine dehydrated colloidal deposits on fresh mica surfaces of the synthetic layered silicate 2:1 smectite clay laponite have been studied by means of atomic force microscopy (AFM). AFM images of these prepared assemblies of sol and gel aggregates have been analyzed both by means of standard AFM Fourier software and a wavelet method. The deposited surfaces show a persistence to antipersistent crossover with a clay concentration dependent crossover length. It is concluded that the crossover length is associated with aggregate size, and further that the persistent roughness at small length scales signals near compact clusters of fractal dimension three, whereas the antipersistent roughness at large length scales signals a sedimentation process.
Resumo:
On 28th August 1207, King John created the Borough of Liverpool by granting its first charter. During the ensuing 800 years Liverpool has experienced a complex and changing social, economic and political history resulting in powerful images of the city and its people. This paper examines the labelling of Liverpool and stereotypes of Scousers. It explains how historical and contemporary events, and their coverage in various arms of the media, construct social and spatial imaginations of the city. This involves a more systematic contribution to the how and why dimensions of negative place imagery and social stereotypes, and enhances our understanding of the processes and issues affecting our interpretations of people and place. The analysis is both historical and contemporaneous in teasing out how previous and current events shape the perceptions of insiders and outsiders. This paper reveals that despite concerted efforts to re-brand Liverpool the city continues to face difficult challenges with ongoing bad publicity and negative place imagery.
Resumo:
The previously reported preparation of 1,3-dimethylimidazolium salts by the reaction of 1,3-dialkylimidazolium-2-carboxylate zwitterions with protic acids has been reinvestigated in detail, leading to the identification of two competing reactions: isomerisation and decarboxylation. The ability to control both pathways allows this methodology to be used as an effective, green, waste-free approach to readily prepare a wide range of ionic liquids in high yields. Additionally, this reaction protocol opens new possibilities in the formation of other imidazolium salts, whose syntheses were previously either very expensive (due to ion exchange protocols involving metals like Ag) or difficult to achieve (due to multiple extractions and large quantities of hard to remove inorganic by-products).