The tribovoltaic devices have demonstrated an enormous current density output from friction. This has attracted attention, and thus, the tribovoltaic device research is expected to grow rapidly, providing mechanical energy harvesting from human motion or mechanical vibrations to power the microdevices. Herein, we are demonstrating the novel tribovoltaic device based on the W/WO 3 Schottky junction enabled by high-energy electrons as in hot-carrier photovoltaic devices. The hot carrier injection from the metal to the semiconductor has been well demonstrated before in light-driven devices but not demonstrated for tribovoltaic devices. Friction-caused electronic excitations on the W needle provide energy for electrons to overcome the Schottky barrier and generate the unbiased current density up to 1270 A m −2 . The amorphous WO 3 derived from magnetron sputtering shows high durability and reliability of the tribovoltaic device.

The worlds growing population demands more food and creates more waste. Economically viable and environmentally friendly would be to use sewage sludge for agricultural production. There are several limitations for this use – heavy metal content, pathogenic microorganisms, helminths etc.. The different methods of treatment of sewage sludge helps to overcome this problem. The aim of the study is to find the effects of treated sewage sludge on the growth of maize and changes in soil biological activity. Experiments were carried out with dry sewage sludge preparation (SSP) in the such combinations 1) SSP, 2) SSP+PK, 3) SSP+NPK. Controls- loamy soil without additional fertilizer, soil mixed with mineral fertilizer (Kristalon 18:18:18). Maize (Zea mays var. saccharata ‘Elan F1’) was grown. Experiments were arranged in 1L vegetation containers placed in open area with additional watering. Plant growth parameters and soil enzymatic activity was detected. The SSP alone and in combination with potassium and phosphorus fertilizers does not provide the maize with the mineral nutrients in appropriate value, therefore, the combination of SSP with nitrogen containing fertilizers significantly improves plant growth and promotes development. The use of SSP increases the microbiological activity of the soil. This can have a beneficial long-term effect on the mineral nutrition of plants.

Conversion of organic-containing sludges to a high value fertilizer is considered to be a rational solution from a recycling point of view. Aerobic respiration could serve as an indicator of stability and maturity of the treated sewage sludge (SS). The aim of this study was to characterize two SS samples, obtained from different wastewater treatment plants („D” and „J”), i.e, at the initial stage of treatment, alone and with amendments. Two methods for estimation of microbial respiration, as well as dehydrogenase activity were used. The SS-J demonstrated the higher microbial biodegradation activity, as compared to SS-D. In experiments with OxiTop® device, statistically significant (p<0.05) differences of the pressure drop between SS-J and SS-D have been revealed. Addition of peat to SS resulted in a more intensive pressure drop, compared to non-amended SS, i.e., -145 hPa vs. -76 hPa for SS-D and-199 hPa vs. -180 hPa for SS-J, respectively. The obtained results represent a methodical approach for characterization of raw SS in order to evaluate the amount of aerobically degradable organic substances and intensity of their oxidation. Further research is needed for highlighting the mechanisms responsible for interrelation of respiration intensity, bacterial community activity and other metabolic changes towards SS stabilization.

The antimicrobial effect of Cu is dependent on several factors, including the physiological state of test-cultures. The present study aimed to compare the antibacterial effect of the newly developed Cu-coated surface, using bacterial cultures of Staphylococcus epidermidis and Pseudomonas putida harvested at exponential (6h) and stationary (24h) phases of growth as well as from a colony. Growth kinetics and cell morphology were characterised for each culture. The colony forming units log reduction values for a Cu-coated surface for cultures at exponential, stationary phase, and from a colony were 1.08, 2.85, and 2.14, respectively, for S. epidermidis, while 1.57, 3.95, and 3.14, respectively, for P. putida. The Cu-coated surface reduced the signal of ATP bioluminescence in both S. epidermidis and P. putida, with the more pronounced inhibition being for the cells at exponential and stationary phase of growth. The data indicated that bacterial cultures at the early exponential stage of growth are more resistant towards antimicrobial surfaces than cells at the stationary phase of growth and from a colony. This fact is of great importance for estimating the efficiency of antimicrobial coatings.

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