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Usual response of organism to viral or bacterial invasion represents antibodies production, qualitative and quantitative changes in composition of biological fluids. These changes influence conformation and surface characteristics of macromolecules (proteins), which become apparent in sessile drying drops, when they form aggregates due to salting-out effect and sediment. The bottom adsorption layers change their adhesive and viscoelastic properties in time depending on fluid composition and structure. The aim of this study was verification the idea of using this phenomenon in rapid vet diagnostics. Milk, blood and serum samples of 183 cows were tested using Drop Drying Technology (DDT). A drop of tested fluid dried on a polished quartz plate, oscillated with constant frequency-60 kHz. Mechanical properties of the drop changed during drying, influenced the electrical conductivity of the quartz plate. This signal was converted to the Acoustical-Mechanical Impedance (AMI) and displayed as a curve in coordinates AMI vs. Time. Shape of the AMI curve reflected this dynamics, and was used as a target for quantitative comparison between * Corresponding author. T. A. Yakhno et al. 2 control and infected animals. Frequency analysis of the estimated parameters of the curves was performed using features of the Excel program. Powerful method of artificial neural network processing of the experimental data was also tested in this work as a possible tool for future development. Significant differences between control, Bovine leucosis virus positive (BLV+) and Bovine tuberculin positive (BTub+) cattle groups were obtained using all biological fluids-blood, serum and milk. We fixed also a season shift of the data, but distinction between groups still remained. In serum and milk some features of the AMI curves were more stable, and retained diagnostic properties when combined winter and spring databases. Further development of DDT is proposed.

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Complex and elegant patterns of rosette, scallop, Chinese arrow and dendrite shapes on microscopic length scales formed as a result of salt-induced protein self-assembly in sessile drying droplets of protein-salt solutions were described in the literature. The authors are confident in protein nature of these patterns because they used fluorochrom-labeled albumin, and carried out their observations under luminescent microscope at the appropriate wavelength. But this point of view seems to be disputable. In this paper, some data are presented to highlight the salt nature of the above-mentioned patterns.