Glassy stability

The aim of this study was to better understand the origin of glassy stability and more particularly to determine the role of both hydration and sucrose on residual molecular mobility in low moisture glasses. 

In addition to the production of stabilized AI2O3 fibres there is also a huge production of melt-spun glassy fibres containing approximately equal proportions by weight of AI2O3 and Si02. This is used mainly for thermal insulation at temperatures up to 1400°C and current world production exceeds 20000 tormes per annum. 

The anodic stability of anions on glassy carbon is the following order BR4 < C104 [Pg.476]

Glassy amorphous polymers exhibit excellent dimensional stability and are frequently transparent. Everyday examples include atactic polystyrene, polycarbonate, and polymethylmethacrylate (Plexiglas ), which we encounter in such applications as bus shelters, motorcycle windshields, and compact disc cases. 

Table 5. Electrochemical stability window of ionic liquids (IL) at the glassy carbon (potentials [V/ expressed versus Ag/Agf 0.01M in DMSO reference) [26 /.

Table 5 shows cathodic and anodic limits of electrochemical stability windows of a number of ionic liquids. The cathodic limit of the stability window of the ILs based on the EMIm+ and BMIm+ cations, investigated at the glassy carbon electrode, is -2.1 V against the Ag/Ag+ (0.01M in DMSO) reference. The BMPy+ cation is reduced at the glassy carbon at considerably more positive potential, at ca. -1.0 V. 

A flow injection optical fibre biosensor for choline was also developed55. Choline oxidase (ChOX) was immobilized by physical entrapment in a photo-cross-linkable poly(vinyl alcohol) polymer (PVA-SbQ) after adsorption on weak anion-exchanger beads (DEAE-Sepharose). In this way, the sensing layer was directly created at the surface of the working glassy carbon electrode. The optimization of the reaction conditions and of the physicochemical parameters influencing the FIA biosensor response allows the measurement of choline concentration with a detection limit of 10 pmol. The DEAE-based system also exhibited a good operational stability since 160 repeated measurements of 3 nmol of choline could be performed with a variation coefficient of 4.5%. 

B. Haghighi, S. Varma, F.M. Alizadeh, Y. Yigzaw, and L. Gorton, Prussian blue modified glassy carbon electrodes - study on operational stability and its application as a sucrose biosensor. Talanta 64, 3-12 (2004). 

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