Systematic mechanical assessment of consolidants for canvas reinforcement under controlled environment

In conservation, adhesives are commonly used for the consolidation of canvases, yet their impact upon the canvas longevity has raised some concerns amongst conservators. As such, this study presents a testing protocol developed to assess the performance of commonly-used adhesives (natural animal glue and synthetic Beva® 371) and a newly developed nanocellulose consolidant, nanofibrillated nanocellulose (CNF). This includes their effect on the visual appearance, consolidation, and response of the mechanical properties of the treated canvases to programmed changes in relative humidity (RH). Scanning electron microscopy (SEM) images of animal glue- and Beva® 371-treated canvases revealed the presence of adhesive and consolidant on and in-between cotton fibres. The consolidants form bridges linking and connecting the cotton fibres and holding them together, whereas the CNF treatment, formed a visible continuous and dense surface coating. None of the treatments induced any discernible colour change. Controlled environment mechanical testing was performed in two ways: by applying a linearly increasing static force at fixed RH (Young’s modulus) and by applying a dynamic force together with a programmed RH cycling between 20 and 80% (RH dependent viscoelastic properties). CNF gave a higher value of Young’s modulus than either of the two commonly-used materials. Measurements at different values of RH (20 and 80%) demonstrated for all the treated canvases that at the lower value (RH 20%) Young’s modulus values were higher than at the higher value (RH 80%). Besides, the dynamic mode showed that the rate of response in all cases was rapid and reversible and that the nanofibrillated cellulose treated sample showed the highest variation in storage (or elastic) modulus measured at the end of RH plateaux (20 and 80% RH). Thus CNF appears to be a promising material given its higher mechanical performance. The protocol developed in this study has enabled us to examine and compare candidate materials for the consolidation of canvases systematically, using testing parameters that remained relevant to the field of canvas conservation

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Resolução temporal auditiva em idosos Auditory temporal resolution in elderly people

OBJETIVO: Avaliar o processamento auditivo em idosos por meio do teste de resolução temporal Gaps in Noise e verificar se a presença de perda auditiva influencia no desempenho nesse teste. MÉTODOS: Sessenta e cinco ouvintes idosos, entre 60 e 79 anos, foram avaliados por meio do teste Gaps In Noise. Para seleção da amostra foram realizados: anamnese, mini-exame do estado mental e avaliação audiológica básica. Os participantes foram alocados e estudados em um grupo único e posteriormente divididos em três grupos segundo os resultados audiométricos nas frequências de 500 Hz, 1, 2, 3, 4 e 6 kHz. Assim, classificou-se o G1 com audição normal, o G2 com perda auditiva de grau leve e o G3 com perda auditiva de grau moderado. RESULTADOS: Em toda a amostra, as médias de limiar de detecção de gap e de porcentagem de acertos foram de 8,1 ms e 52,6% para a orelha direita e de 8,2 ms e 52,2% para a orelha esquerda. No G1, estas medidas foram de 7,3 ms e 57,6% para a orelha direita e de 7,7 ms e 55,8% para a orelha esquerda. No G2, estas medidas foram de 8,2 ms e 52,5% para a orelha direita e de 7,9 ms e 53,2% para a orelha esquerda. No G3, estas medidas foram de 9,2 ms e 45,2% para as orelhas direita e esquerda. CONCLUSÃO: A presença de perda auditiva elevou os limiares de detecção de gap e diminuiu a porcentagem de acertos no teste Gaps In Noise.<br>PURPOSE: To assess the auditory processing of elderly patients using the temporal resolution Gaps-in-Noise test, and to verify if the presence of hearing loss influences the performance on this test. METHODS: Sixty-five elderly listeners, with ages between 60 and 79 years, were assessed with the Gaps-in-Noise test. To meet the inclusion criteria, the following procedures were carried out: anamnesis, mini-mental state examination, and basic audiological evaluation. The participants were allocated and studied as a group, and then were divided into three groups, according to audiometric results for the frequencies of 500 Hz, 1, 2, 3, 4 and 6 kHz. Thus, subjects in G1 had normal hearing, participants in G2 were classified with mild hearing loss, and those in G3 had moderate hearing loss. RESULTS: In the entire sample, the mean gap detection threshold and the mean percentage of correct responses were, respectively, 8.1 ms and 52.6% for the right ear, and 8.2 ms and 52.2% for the left ear. In G1, these measures were 7.3 ms and 57.6% for the right ear, and 7.7 ms and 55.8% for the left ear. In G2, these measures were 8.2 ms and 52.5% for the right ear, and 7.9 ms and 53.2% for the left ear. In G3, the measures were 9.2 ms and 45.2% for the right and left ears. CONCLUSION: The presence of hearing loss increased the gap detection thresholds and lowered the percentage of correct responses on the Gaps-in-Noise test