Pathways of α-methylstyrene Oxidation by P. aeruginosa DS-26

Today in world practice the biotechnological methods of cleaning of environment from oil and oil products are widely used. They based on the use of microorganisms-destructors that are able to utilize hydrocarbons. The microbial object of the research was bacterial strain P. aeruginosa DS-26. This bacterial culture was isolated from sewage water of rubber industry. This strain was able to grow in a medium, which contained α-methylstyrene. This compound, which is widely used as an active component in many industries, has a strong toxic effect on living organisms including humans. Different types of microbial metabolism play an important role in the hydrocarbon degradation process in the environment Metabolism of α-methylstyrene by P. aeruginosa DS-26 characterized by variety and in depth of carried out transformations. The analysis of the obtained data allowed offering two ways of oxidation of α-methylstyrene. The first way, primary, was accompanied by formation of products of the direct hydroxylation of aromatic ring - cis-2.3-dihydroxy-1-isopropenyl-6-cyclohexene and 3-isopropyl-catehol which are later metabolized by meta-pathway with formation of keto-acids. The next, secondary pathway came true through oxidation of α-phenylpropionic acid and 4-methylbenzene alcohol with formation of acetophenone as a final product. There are many researches that are devoted to study biochemical conversion of oil hydrocarbons. In order to utilize specific compounds as the only one source of carbon,  microorganisms have to actively maintain a specific system of enzymes. Investigation of α-methylstyrene degradation by P. aeruginosa DS26 enzymes has revealed specific enzymes that oxidize aromatic hydrocarbons. Investigation results of the studying strain enzymes can be confirmation of the proposed above scheme of primary α-methylstyrene metabolic pathway oxidized by P. aeruginosa DS-26

Processing of AC-coupled n-in-p pixel detectors on MCz silicon using atomic layer deposited aluminium oxide

We report on the fabrication of capacitively (AC) coupled n(+)-in-p pixel detectors on magnetic Czochralski silicon substrates. In our devices, we employ a layer of aluminium oxide (Al2O3) grown by atomic layer deposition (ALD) as dielectric and field insulator, instead of the commonly used silicon dioxide (SiO2). As shown in earlier research, Al2O3 thin films exhibit high negative oxide charge, and can thus serve as a substitute for p-stop/p-spray insulation implants between pixels. In addition, they provide far higher capacitance densities than SiO2 due to their high dielectric constant, permitting more efficient capacitive coupling of pixels. Furthermore, metallic titanium nitride (TiN) bias resistors are presented as an alternative to punch-through or poly-Si resistors. Devices obtained by the above mentioned process are characterized by capacitance-voltage and current-voltage measurements, and by 2 MeV proton microprobe. Results show the expected high negative charge of the Al2O3 dielectric, uniform charge collection efficiency over large areas of pixels, and acceptable leakage current densities.Peer reviewe

Characterization of magnetic Czochralski silicon devices with aluminium oxide field insulator : effect of oxygen precursor on electrical properties and radiation hardness

Aluminium oxide (Al2O3) has been proposed as an alternative to thermal silicon dioxide (SiO2) as field insulator and surface passivation for silicon detectors, where it could substitute p-stop/p-spray insulation implants between pixels due to its negative oxide charge, and enable capacitive coupling of segments by means of its higher dielectric constant. Al2O3 is commonly grown by atomic layer deposition (ALD), which allows the deposition of thin layers with excellent precision. In this work, we report the electrical characterization of single pad detectors (diodes) and MOS capacitors fabricated on magnetic Czochralski silicon substrates and using Al2O3 as field insulator. Devices are studied by capacitance-voltage, current-voltage, and transient current technique measurements. We evaluate the influence of the oxygen precursors in the ALD process, as well as the effect of gamma irradiation, on the properties of these devices. We observe that leakage currents in diodes before the onset of breakdown are low for all studied ALD processes. Charge collection as measured by transient current technique (TCT) is also independent of the choice of oxygen precursor. The Al2O3 films deposited with O-3 possess a higher negative oxide charge than films deposited by H2O, However, in diodes a higher oxide charge is linked to earlier breakdown, as has been predicted by simulation studies. A combination of H2O and O-3 precursors results in a good compromise between the beneficial properties provided by the respective individual precursors.Peer reviewe

Role of genetic polymorphisms in tumour angiogenesis

Angiogenesis plays a crucial role in the development, growth and spread of solid tumours. Pro- and anti-angiogenic factors are abnormally expressed in tumours, influencing tumour angiogenesis, growth and progression. Polymorphisms in genes encoding angiogenic factors or their receptors may alter protein expression and/or activity. This article reviews the literature to determine the possible role of angiogenesis-related polymorphisms in cancer. Further research studies in this potentially crucial area of tumour biology are proposed

Degradation of haloaromatic compounds

An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level

Reactions of "hybrid" Mn-peroxidase of the white rot fungus Panus tigrinus with benzylic alcohols in the presence of mediators

"Hybrid" Mn-peroxidase (hMnP) isolated from the white rot fungus Panus tigrinus 8/18 was studied with respect to its reactions with veratryl alcohol in the presence of typical laccase mediators in the reaction mixture. Eight compounds were tested as potential mediators in this reaction and only 1-hydroxybenzotriazole (HBT) and 3-hydroxy-1,2,3-benzotriazin-4(3H)-one (HBTO) were found to be effective. Up to 99% of 1 M veratryl alcohol was oxidized with formation of veratraldehyde as a reaction product over 24 h depending on the buffer system used. Except for veratryl alcohol, anisyl alcohol but not benzyl alcohol was oxidized in this reaction. Reactions with the participance of mediators were not catalytic, and the mediators were consumed during reaction with formation of dehydroxylated derivatives. Reactions with both HBT and HBTO resulted in temporal inactivation of hMnP. Kinetics of hMnP inactivation revealed it to be a pseudo-third order reaction. Investigation of the transformation of the absorption spectra of hMnP redox cycle intermediates in the presence of HBT or HBTO showed that the most likely reason of hMnP inactivation was its interaction with non-oxidized mediators