Determination of low molecular weight organic acids (LMWOAs) in environmental samples

This paper presents a quick method to identify and quantify ten low molecular weight organic acids in environmental samples (e.g., soil, cultivation substrate). The procedure involves extraction of the acids from the sample with a dilute acid of a pH of 2, followed by the separation and quantification of ten acids, i.e., oxalic, formic, acetic, malic, maleic, lactic, malonic, succinic, fumaric, and citric, by reversed-phase liquid chromatography (RPLC). The detection limit was in the range from 8.6 × 10-4 nM to 0.014 microM, with recovery in the range from 60 to 100%. A proven method was applied for the determination of exudate components in the king oyster mushroom (Pleurotus eryngii) post-cultivation straw substrate spiked individually with Cu2+, Co2+, Cd2+, Zn2+ and Ni2+ at 10 mM. The generation/exudation of LMWOAs was metal dependent and was strongly induced by Ni and Cd, less induced by Co and Cu, and suppressed by Zn ions. At 10 mM of Ni, the total concentration of the acids was about 6 times as high as that of the control. We can assume that particular metals alter the mycelium growth and mushroom physiology mainly through the competitive inhibition of nutrients such as Fe and Ca, and also by the inactivation of metalloenzymes, responsible for the substrate mineralization and antioxidant potential. Moreover, organic ligands do not only enhance the solubility of the trace metals, but also they reduce their toxicity to the mushroom, increasing uptake/accumulation abilities during bioremediation of soil/medium contaminated with heavy metals

Testing of internal combustion engines of motorcycles with the use of thermal imaging methods

The internal combustion engine should be rated for the thermal loads that come from different sources. Thermal analysis is important both for design purposes and for evaluating the conditions of its use. Very good results are obtained by a combination of non-invasive measurement techniques, such as research using infrared thermal imaging techniques [3, 11]. The purpose of the study was to determine the engine thermal load by evaluating the average temperature on the outside surface of the engine at many of its points for two selected motorcycle engines with similar displacement capacities. For many reasons, such as ecology, durability, engine strength and thermal performance when heating and cooling are critical. To accomplish this task, a thermographic technique for indirect evaluation has been used, thus creating the possibility of measuring the temperature in a dynamic manner. These are accurate measurements and most importantly do not interfere with the construction of the object under investigation. The engine was tested during operation according to external and load characteristics. As a result of the work, graphs of temperature curves of heating and cooling of the tested engines were compiled. The article presents a methodology for measuring the temperature fields of outer surface engines. The collected material will be used in the future for studying the equable load on the cylinders, and as accurately as possible determine the conditions of movement such as power, revolutions, flow rates, temperatures and pressures