Active middle-ear implant fixation in an unusual place: clinical and audiological outcomes.

OBJECTIVE: The Vibrant Soundbridge is an active middle-ear implant for hearing rehabilitation that is usually placed in the long process of the incus or round window. This study reports on the unusual implant attachment to the short process of the incus in a patient with ear malformation, and describes their audiological and clinical outcomes. METHODS: Case report and literature review. RESULTS: Audiological evaluation with the Vibrant Soundbridge implant showed a pure tone average of 31 dB. The speech test, at 65 dB HL, revealed correct recognition of 92 per cent of disyllabic words. The Glasgow Hearing Aid Benefit Profile showed high levels of satisfaction, hearing aid use and benefit. CONCLUSION: Fixation of the Vibrant Soundbridge implant on the short process of the incus is a feasible option, with good clinical and audiological outcomes. Coupling the floating mass transducer to the short process of the incus is a good surgical option, especially when the long process and the oval or round window are inaccessible.

Rheology and dynamic light scattering of octa-ethyleneglycol-monododecylether/chitosan solutions.

In this work we used rheometry and DLS to probe relaxation phenomena in solutions of chitosan and octa-ethyleneglycol-monododecylether. The dispersions had a marked pseudoplastic behavior, which became less evident, as surfactant concentration was increased. Arrhenius plots showed that systems with surfactant presented a characteristic temperature at which apparent enthalpy of activation (varying from 3 to 40 kJ mol(-1)) changed: this change was correlated to a possible transition of colloidal aggregates to a wormlike configuration. DLS intensity correlation functions were described by KWW equation: pure chitosan solutions had relaxation rate distributions centered at a characteristic relaxation rate around 4.6×10(-6) µS(-1); as surfactant was added, a new component, with a faster characteristic relaxation rate with a magnitude order of 10(-3) µs(-1), appeared. It was shown that the dependence between these relaxation rates and surfactant concentration could be used to describe DLS-related relaxation phenomena as an Arrhenius-activated process, agreeing with results obtained using rheometry.

Determination of deacetylation degree of chitosan: a comparison between conductometric titration and CHN elemental analysis.

Chitosan is a polysaccharide used in a broad range of applications. Many of its unique properties come from the presence of amino groups in its structure. A proper quantification of these amino groups is very important, in order to specify if a given chitosan sample can be used in a particular application. In this work, a comparison between the determination of chitosan degree of deacetylation by conductometry and CHN elemental analysis was carried out, using a rigorous error analysis. Accurate expressions relating CHN composition, conductometric titration, and degree of deacetylation, in conjunction with their associated errors, were developed and reported in this note. Error analysis showed conductometric analysis as an inexpensive and secure method for the determination of the degree of deacetylation of chitosan.