Silica Nanowires Templated by Amyloid‐like Fibrils

Many peptides self‐assemble to form amyloid fibrils. We previously explored the sequence propensity to form amyloid using variants of a designed peptide with sequence KFFEAAAKKFFE. These variant peptides form highly stable amyloid fibrils with varied lateral assembly and are ideal to template further assembly of non‐proteinaceous material. Herein, we show that the fibrils formed by peptide variants can be coated with a layer of silica to produce silica nanowires using tetraethyl‐orthosilicate. The resulting nanowires were characterized using electron microscopy (TEM), X‐ray fiber diffraction, FTIR and cross‐section EM to reveal a nanostructure with peptidic core. Lysine residues play a role in templating the formation of silica on the fibril surface and, using this library of peptides, we have explored the contributions of lysine as well as arginine to silica templating, and find that sequence plays an important role in determining the physical nature and structure of the resulting nanowires.     

Eine Neubestimmung des Aequivalentgewichtes des Titans

Ohne Zusammenfassung     

Zur Bestimmung von ?thylalkohol

Ohne Zusammenfassung     

A method for the study of surface corrosion beneath protective layers

This work is concerned with the development of a technique to observe the onset of corrosion as it occurs beneath a temporary protective layer. Such temporary protectives include paints, varnishes, greases and oils that are applied to metal surfaces to give short-term protection from corrosion. The objective of this project was to develop a technique that could be used to evaluate the effectiveness of various temporary protectives in different environments, without the need to remove the protective layer, thus eliminating the possibility of any chemical changes or loss of corrosion products occurring as a result of removal. The temporary protective layers are typically 25Μm for paints and 15Μm per layer for varnishes. The 6.3 keV fluorescence X-ray is able to penetrate such layers, but the large escape depth (∼10Μm) of the X-rays means that for a thin protective layer a large proportion of the X-rays detected will originate from deep within the substrate and the resultant spectrum will be representative of the bulk rather than the surface. To enhance the surface sensitivity of the CXMS technique, the near surface region must be enriched in the isotope Fe-57. To achieve this, Fe-57 was vacuum evaporated onto the surface of mild steel substrates and subsequently diffused into the near surface region. An approximate 20 nm Fe-57 layer was deposited onto mild steel samples. The surface enriched samples were then annealed to allow the Fe-57 to diffuse into the near surface region of the mild steel substrate, and also to allow back diffusion of the substrate. A diffusion model was developed to predict the surface distribution of Fe-57 as a function of annealing parameters. The computer diffusion model allowed the ideal annealing conditions to be estimated to obtain a required near surface environment. It was essential that the annealing conditions did not result in any surface oxidation, and did result in a surface that was characteristic of mild steel. CEMS and CXMS spectra were recorded of samples before and after annealing, and also dynamic Secondary Ion Mass Spectrometry (SIMS) was used to monitor the enrichment and diffusion process. Energy Dispersive X-ray Analysis (EDXA) was also used to characterize the surface. A number of enriched samples were prepared and treated with a variety of surface temporary protectives. The CXMS spectra were recorded before and after exposure of the coated samples to various aggressive environments.     

Das Atomgewicht des Goldes

Ohne Zusammenfassung     

Nachweis von Arsen

Ohne Zusammenfassung     

Auditory sensitivity in preschool children

Thresholds for octave-band noises with center frequencies of 0.4, 1, 2, 4, and 10 kHz, and 1/3-octave-band noises with center frequencies of 10 and 20 kHz, were obtained from children 3-5 years of age and from a comparison group of adults. Thresholds for all frequencies decreased between 3 and 5 years of age. Thresholds decreased further between 5 years of age and adulthood, except for the 20-kHz stimulus, for which children had lower thresholds than adults. These results are discussed in terms of possible age-related changes in the mechanical properties of the ear and in the efficiency of neural coding.