Enzymatic reactions in anaerobic 2-methylnaphthalene degradation by the sulphate-reducing enrichment culture N 47.

The upper pathway of anaerobic degradation of 2-methylnaphthalene was studied with a sulphate-reducing enrichment culture, which is able to grow with naphthalene or 2-methylnaphthalene as sole carbon source and electron donor. Anaerobic degradation of 2-methylnaphthalene is initiated by an addition of fumarate to the methyl-group producing the first intermediate, naphthyl-2-methyl-succinate. In a subsequent P-oxidation of the original methyl atom, the central metabolite 2-naphthoic acid is generated. In the following pathway, the aromatic ring system is reduced, cleaved, and finally oxidised to CO2. Here, we present two new enzymatic reactions of the 2-methylnaphthalene degradation pathway that were measured in crude cell extracts. All metabolites were identified with HPLC by co-elution with synthesised reference substances. The first enzyme, succinyl-CoA:naphthyl-2-methyl-succinate CoA-transferase, catalyses the activation of naphthyl-2-methyl-succinic acid to the corresponding CoA ester. The average specific activity of this enzyme was 19.6 nmol x min(-1) x mg of protein(-1). The CoA-transfer was not inhibited by sodium borohydride and only partially by hydroxylamine, indicating that this enzyme belongs to the family III of CoA-transferases like the corresponding enzyme in the anaerobic toluene degradation pathway. The product of this CoA-transfer reaction, naphthyl-2-methyl-succinyl-CoA is then oxidised in a reaction to naphthyl-2-methylene-succinyl-CoA by the enzyme naphthyl-2-methyl-suceinyt-CoA dehydrogenase. The specific activity of this enzyme was 0.115 nmol x min(-1) x mg of protein(-1). The enzymatic activity could only be detected using phenazine methosulphate as electron acceptor. No activity was observed with natural electron acceptors such as nicotinamide adenine dinucleotide or flavin adenine dinucleotide. The two novel reactions presented here demonstrate that the original methyl-group of 2-methylnaphthalene is oxidised to the carboxyl group of 2-naphthoic acid in the upper part of the anaerobic degradation pathway

New possibilities of application of magnetoelastic sensors for torque measurement in ball valves

W referacie przedstawiono nowe możliwości zastosowania sensorów magnetosprężystych z rdzeniami z taśm amorficznych do pomiaru momentu skręcającego wytwarzanego w trakcie pracy zaworu kulowego. Wyniki pomiarów wskazują na w przybliżeniu liniową zmianę wartości momentu skręcającego w funkcji kąta obrotu trzpienia zaworu również w momencie początkowym, w którym konieczne jest pokonanie oporów wynikających z tarcia statycznego.Measurements of torque during the operations of ball valve have great practical significance. Changes of value of torque may indicate malfunction of such valve. Paper presents new method of real-time measurements of torque in ball valve utilizing magnetoelastic sensors with amorphous alloy cores. Figure 1 presents the general, schematic block diagram describing operation of magnetoelastic sensor. In Figures 2 and 3 technical solution for magnetoelastic torque sensors is presented. In this solution uniform shearing stresses may be achieved in ring-shaped magnetoelastic core made of amorphous alloy. Figure 4 presents view of system for measurements of torque in ball valves, composed of magnetoelastic sensor, pneumatic actuator as well as 2 inch SNL ball valve. Results of experiments presented in Figure 5 indicate nearly linear characteristics of torque versus angle of valve's spindle. This phenomenon was observed also in initial range of valve operation, where static rubbing has to be overcame. Probably linear characteristic of torque versus angle is connected with the presence of elastic seal covering the ball in the valve

Combined application of stable carbon isotope analysis and specific metabolites determination for assessing in situ degradation of aromatic hydrocarbons in a Tar oil-contaminated aquifer.

To evaluate the intrinsic bioremediation potential in an anoxic tar oil-contaminated aquifer at a former gasworks site, groundwater samples were qualitatively and quantitatively analyzed by compound-specific isotope analysis (CSIA) and signature metabolites analysis (SMA). C-13/C-12 fractionation data revealed conclusive evidence for in situ biodegradation of benzene, toluene, o-xylene, m/p-xylene, naphthalene, and 1-methylnaphthalene. In laboratory growth studies, C-13/C-12 isotope enrichment factors for anaerobic degradation of naphthalene (epsilon = -1.1 +/- 0.4) and 2-methylnaphthalene (epsilon = -0.9 +/- 0.1) were determined with the sulfate-reducing enrichment culture N47, which was isolated from the investigated test site. On the basis of these and other laboratory-derived enrichment factors from the literature, in situ biodegradation could be quantified for toluene, o-xylene, m/p-xylene, and naphthalene. Stable carbon isotope fractionation in the field was also observed for ethylbenzene, 2-methylnaphthalene, and benzothiophene but without providing conclusive results. Further evidence for the in situ turnover of individual BTEX compounds was provided by the presence of acetophenone, o-toluic acid, and p-toluic acid, three intermediates in the anaerobic degradation of ethylbenzene, o-xylene, and p-xylene, respectively. A number of groundwater samples also contained naphthyl-2-methylsuccinic acid, a metabolite that is highly specific for the anaerobic degradation of 2-methylnaphthalene. Additional metabolites that provided evidence on the anaerobic in situ degradation of naphthalenes were 1-naphthoic acid, 2-naphthoic acid, 1,2,3,4-tetrahydronaphthoic acid, and 5,6,7,8-tetrahydronaphthoic acid. 2-Carboxybenzothiophene, 5-carboxybenzothiophene, a putative further carboxybenzothiophene isomer, and the reduced derivative dihydrocarboxybenzothiophene indicated the anaerobic conversion of the heterocyclic aromatic hydrocarbon benzothiophene. The combined application of CSIA and SMA, as two reliable and independent tools to collect direct evidence on intrinsic bioremediation, leads to a substantially improved evaluation of natural attenuation in situ

Development of Graphene Based Flow Sensor

This paper shows the research on a flow sensor based on graphene. Presented Results show the linear relation between voltage induced on graphene layer and flow velocity. The measurement shows that signal level is relatively low, and it is highly correlated with the time of the sample being submerged in water. A significant temperature dependency has been shown which indicates on necessity to develop a compensation system for the sensor. On the other hand, induced voltage is related to ion concentration of the liquid, so the sensor must be recalibrated for every working environment. The most important thing that turned out during research is that although the voltage signal itself is highly inconsistent, the difference between its value in steady state and for flowing liquid is always visible and correlated to the flow value – this property can be used in further deployment. Huge advantage of the sensor is also its scalability which opens so far unknown possibilities of applications