Oxygen reduction reaction on covalently and noncovalently modified carbon nanowalls

An effect of highly oriented carbon nanowalls modification on oxygen reduction reaction was studied by means of a rotating disk electrode. Namely nanowalls were modified with oxygencontaining functional groups. Moreover, an adsorption of borneol (a surfactant with twodimensional structure) was considered. Two distinct waves are observed on voltammograms in aerated alkaline solutions that points out to the two-step process of oxygen reduction with the formation of H2O2 as intermediate. Both types of surface modification were found to affect substantially the absolute currents of the waves as well as their ratio. This effect was assumed to be caused by the topology peculiarities of carbon nanowalls that determine the electrochemical heterogeneity of the electrode surface. For initial nanowalls, the process of two-step reduction takes place on the edges of nanowalls. A parallel channel of oxygen reduction with the formation of water is assumed to be realized on the defects of basal planes at high overvoltage. In the case of noncovalent modification, borneol is adsorbed mainly on basal planes of nanowalls and blocks substantially parallel reduction channel. After covalent modification, oxygen reduction proceeds mainly through a two-step channel as a result of the increase in the number of oxygen-containing functional groups (the centers of two-step reduction) on the edges of nanowalls

Biomonitoring for wide area surveying in landmine detection using honeybees and optical sensing

This project has received funding from NATO Science for Peace & Security under grant agreement MYP G5355, and the Engineering and Physical Sciences Research Council under EP/K503940/1.Humanitarian demining is a worldwide effort and the range of climates and environments prevent any one detection method being suitable for all sites, so more tools are required for safe and efficient explosives sensing. Landmines emit a chemical flux over time, and honeybees can collect the trace residues of explosives (as particles or as vapour) on their body hairs. This capability was exploited using a passive method allowing the honeybees to freely forage in a mined area, where trace explosives present in the environment stuck to the honeybee body, which were subsequently transferred onto an adsorbent material for analysis by a fluorescent polymer sensor. Potential false positive sources were investigated, namely common bee pheromones, the anti-varroa pesticide Amitraz, and the environment around a clean apiary, and no significant response was found to any from the sensor. The mined site gave a substantial response in the optical sensor films, with quenching efficiencies of up to 38%. A model was adapted to estimate the mass of explosives returned to the colony, which may be useful for estimating the number of mines in a given area.PostprintPeer reviewe

Physicochemical Properties, Cytotoxicity, and Antioxidative Activity of Natural Deep Eutectic Solvents Containing Organic Acid

Natural deep eutectic solvents (NADES) may be considered ‘designer solvents’ due to their numerous structural variations and the possibility of tailoring their physicochemical properties. Prior to their industrial application, characterization of NADES is essential, including determination of their physicochemical properties, cytotoxicity, and antioxidative activity. The most important physicochemical properties of eight prepared NADES (choline chloride:malic acid, proline:malic acid, choline chloride:proline:malic acid, betaine:malic acid, malic acid:glucose, malic acid:glucose:glycerol, choline chloride:citric acid, and betaine:citric acid) were measured as functions of temperature and water content. In general, the structure of prepared NADES greatly influences their physical properties, which could be successfully modified and adjusted by addition of water. All tested NADES were absolutely benign and noncorrosive for investigated steel X6CrNiTi18-10. Furthermore, cytotoxicity of prepared solvents was assessed toward three human cell lines (HEK-293T, HeLa, and MCF-7 cells), and antioxidative activity was measured by the Oxygen Radical Absorbance Capacity (ORAC) method. With regard to cell viability, all tested NADES containing carboxylic acid could be classified as practically harmless and considered environmentally safe. The ORAC values indicated that the tested NADES displayed antioxidative activity

Renewable Energy - Wind Turbines, Solar Cells, Small Hydroelectric Plants, Biomass, and Geothermal sources of energy

Renewable Energy - Wind Turbines, Solar Cells, Small Hydroelectric Plants, Biomass, and Geothermal sources of energy, New Functional Materials and Hight Technologies, Tivat, Montenegr

Effect of herbicides on microbiological properties of soil

Microorganisms decompose herbicides and they may serve as bioindicators of soil changes following herbicide application. Certain microbial species may be used as bioherbicides. This study has shown that Azotobacter is most sensitive to herbicide application; it is, therefore, a reliable indicator of the biological value of soil. The numbers of this group of nitrogen-fixing bacteria decrease considerably in the period of 7-14 days after herbicide application. Simultaneously, the numbers of Actinomycetes and less so of fungi increase, indicating that these microorganisms use herbicides as sources of biogenous elements. Rate of herbicidal decomposition depends on the properties of the preparation applied herbicide dose as well as on the physical and chemical soil properties, soil moisture and temperature, ground cover, agrotechnical measures applied and the resident microbial population

Biologically inspired features used for robust phoneme recognition

Formants are regarded as the basic building blocks of vowels; however, they are very rarely used as features for difficult automatic speech recognition tasks. Formant-based research is generally focused on formant extraction, because of the assumption that a better formant extraction method is the only manner to increase the effectiveness of formants. We challenge this assumption by investigating a different use of formants following their extraction. By using the same principles of combining formants as observed in speech perception studies, we create features that show good recognition performance under noisy testing conditions. Improved recognition performance with the proposed formant features is demonstrated by comparing to Mel-frequency cepstrum coefficients and perceptual linear predictive coding features on a hidden Markov model-based automatic speech recognition system.Griffith Sciences, Griffith School of EngineeringNo Full Tex

Investigation of Efficiency of Use of High-Temperature Greases in Steel Rolling - Part 1

It has been shown the efficiency of use of high-temperature greases “Natol-H-1(2)” in steel rolling in the result of research of friction coefficients (steel-to-steel) for various rolling pressures on application of greases “Natol”. Medium-temperature putted greases Natol-M-1(2) and pumpable consistent greases “Natol-Р-1(2, 3)” are not suitable for steel rolling. The influence of various components and their percentages in greases on magnitude of friction coefficients was found.</jats:p