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We report a novel biodegradable piezoelectric composite fabricated from paper and the piezoelectric salt, sodium potassium tartrate tetrahydrate (Rochelle salt, which we term PiezoSalt). The piezoelectric composite is non-toxic and is fabricated free of environmentally harmful solvents by impregnating PiezoSalt into a paper matrix through the crystallization of a concentrated PiezoSalt brine solution. The composite exhibits an effective piezoelectric constant between 3 and 25 pC N-1, dielectric constant of 7, mass density of 625 kg m(-3), and a Young's modulus between 7 and 8 GPa. When directly actuated, cm-scale cantilevers consisting of PiezoSalt paper produced clearly audible sound waves, illustrating one potential application. PiezoSalt paper composite provides a scalable, high throughput approach for biodegradable sensors and transducers with unsurpassed environmentally friendly processing. (C) 2016 Elsevier B.V. All rights reserved.

Herak D., Kabutey A., Sedlacek A., Gűrdil G. , 2011. Tangent curve utilization for description of mechanical behaviour of pressed mixture . Res. Agr. Eng., 57: 13-18. This article is focused on the utilization of tangent curve for description of mechanical behaviour of pressed mixture under compression loading. The aim of this experiment was to determine the general equation describing deformation characteristics of pressed mixtures under compression loading and to verify this equation. The experiment was carried out using mixture of seeds of common sunflower ( Heliantus annuus L.), jatropha ( Jatropha curcas L.), garden pea ( Pisum sativum L.), common bean ( Phaseolus vulgaris L.), and also mixture of spruce wood chips and waste paper chips. The results from the experiment showed that mechanical behaviour of the pressed mixtures under compression loading can be described by tangent curve function. From the determined coefficients of determination R 2 it was clear that fitted tangent curve functions described the measured amounts exactly for all pressed mixtures. It can be therefore assumed that this tangent curve function is appropriate for use in pressing any pressed mixtures during linear compression.