The paper deals with a functional instability of electronic nose (e-nose) units which significantly limits their real-life applications. Here we demonstrate how to approach this issue with example of an e-nose based on a metal oxide sensor array developed at the Karlsruhe Institute of Technology (Germany). We consider the instability of e-nose operation at different time scales ranging from minutes to many years. To test the e-nose we employ open-air and headspace sampling of analyte odors. The multivariate recognition algorithm to process the multisensor array signals is based on the linear discriminant analysis method. Accounting for the received results, we argue that the stability of device operation is mostly affected by accidental changes in the ambient air composition. To overcome instabilities, we introduce the add-training procedure which is found to successfully manage both the temporal changes of ambient and the drift of multisensor array properties, even long-term. The method can be easily implemented in practical applications of e-noses and improve prospects for device marketing.

This work presents Fe₃O₄ and AgFe nanoparticles with an average diameter of 25 and 15 nm synthesized by chemical reduction of corresponding salts under a mild condition. Cubic crystal structure and spherical shape of the nanoparticles were studied by X-ray diffraction, Field emission SEM and energy-dispersive spectroscopy analysis. For biomedical applications, the nanoparticles were tested against bacteria E.coli and results revealed AgFe nanoparticles’ antibacterial activity by forming lysis zone in scale of 0.5 mm.

Pulsed plasma in liquid is a simple, ecologically friendly, cost-efficient method based on electrical discharge between two metal electrodes submerged into a dielectric liquid. We synthesized carbon-encapsulated Fe (Fe@C) magnetic nanoparticles with low cytotoxicity using pulsed plasma in a liquid. Body-centered cubic Fe core nanoparticles showed good crystalline structures with an average size between 20 and 30 nm were encapsulated in onion-like carbon coatings with a thickness of 2–10 nm. Thermal gravimetric analysis showed a high stability of the as-synthesized samples under thermal treatment and oxidation. Cytotoxicity measurements showed higher cancer cell viability than samples synthesized by different methods. Carbon coated ZnO nanorods with about 20 nm thickness and 150 nm length were synthesized by this method using different surfactant materials such as cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS). Cu and Ag nanoparticles of about 10 nm in size were also synthesized by the pulsed plasma in aquatic solution of 0.2 % gelatine as surfactant material. These nanoparticles showed high antibacterial activity for Erwinia amylovora and Escherichia coli.

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The study aimed to expand the range of dairy products by developing a recipe and technology for a fermented milk drink made from donkey milk with unique properties. Additional functionality is provided by the introduced probiotic cultures and phytogenic raw materials. Two functional drinks were proposed as experimental products: Koumiss-1 - koumiss with added probiotics and peony tincture, and Koumiss-2 - probiotic koumiss with added dried burdock roots. The initial raw material, donkey milk, was collected in the farm of the Ala Too State Farm located at an altitude of 800 m above sea level, in the Chui Valley of the Kyrgyz Republic. The standard methods of physicochemical, microbiological and organoleptic analyses were used for the study. The fermentation intensity (Is) and fermentation coefficient (δ) were determined for each case based on the data on the change in active and titratable acidity during the fermentation of milk with koumiss ferment. In the sample of koumiss-1 with the addition of peony tincture δ appeared in the first 3 hours, and δ in koumiss-2 was closer to 6 hours. Based on organoleptic evaluations, the developed drinks exhibit a pleasant sour-milk aroma and taste. The consistency is liquid with a slightly foamy texture, while the drink with added burdock roots has a pleasant creamy flavor. Lactic acid bacteria and yeast are similar to the specifications found in natural koumiss made from mare's milk. Throughout the experiment, sour-milk beverages were successfully produced, and they can potentially to fill the market niche for functional products with medicinal properties.