Repair of a damaged turbocharger

The turbocharger is among the highest quality assemblies for modern internal combustion engines. Its contribution to engine operation is immeasurable – it increases the power output of the engine while indirectly reducing fuel consumption. Like all devices, turbochargers require quality maintenance as they are susceptible to failure. Faulty turbochargers are either repaired or replaced with new ones. Repair ensures substantial financial savings. The paper presents the consequences of damage to the turbocharger and the process of its repair

Repair of a damaged turbocharger

The turbocharger is among the highest quality assemblies for modern internal combustion engines. Its contribution to engine operation is immeasurable – it increases the power output of the engine while indirectly reducing fuel consumption. Like all devices, turbochargers require quality maintenance as they are susceptible to failure. Faulty turbochargers are either repaired or replaced with new ones. Repair ensures substantial financial savings. The paper presents the consequences of damage to the turbocharger and the process of its repair

Paralelo 36

The evaporation of droplets occurs in a large variety of natural and technological processes such as medical diagnostics, agriculture, food industry, printing, and catalytic reactions. We study the different droplet morphologies adopted by an evaporating droplet on a surface with an elliptical patch with a different contact angle. We perform experiments to observe these morphologies and use numerical calculations to predict the effects of the patched surfaces. We observe that tuning the geometry of the patches offers control over the shape of the droplet. In the experiments, the drops of various volumes are placed on elliptical chemical patches of different aspect ratios and imaged in 3D using laser scanning confocal microscopy, extracting the droplets shape. In the corresponding numerical simulations, we minimize the interfacial free energy of the droplet, by employing Surface Evolver. The numerical results are in good qualitative agreement with our experimental data and can be used for the design of micropatterned structures, potentially suggesting or excluding certain morphologies for particular applications. However, the experimental results show the effects of pinning and contact angle hysteresis, which are obviously absent in the numerical energy minimization. The work culminates with a morphology diagram in the aspect ratio vs relative volume parameter space, comparing the predictions with the measurements

Dynamics in the dimerised and high field incommensurate phase of CuGeO3_3

Temperature ($2.3<T<40$\ K) and magnetic field ($0<B<17$\ T) dependent far infrared absorption spectroscopy on the spin-Peierls coumpound CuGeO$_3$\ has revealed several new absorption processes in both the dimerised and high field phase of CuGeO$_3$. These results are discussed in terms of the modulation of the CuGeO$_3$\ structure. At low fields this is the well known spin-Peierls dimerisation. At high fields the data strongly suggests a field dependent incommensurate modulation of the lattice as well as of the spin structure.Comment: 12 pages (revtex), 2 figures (eps), csh selfextracting .uu file, To appear in PRB-Rapid Com

Revival of the spin-Peierls transition in Cu_xZn_(1-x)GeO_3 under pressure

Pressure and temperature dependent susceptibility and Raman scattering experiments on single crystalline Cu_xZn_(1-x)GeO_3 have shown an unusually strong increase of the spin-Peierls phase transition temperature upon applying hydrostatic pressure. The large positive pressure coefficient (7.5 K/GPa) - almost twice as large as for the pure compound (4.5 K/GPa) - is interpreted as arising due to an increasing magnetic frustration which decreases the spin-spin correlation length, and thereby weakens the influence of the non-magnetic Zn-substitution.Comment: LaTeX, 15 pages, 5 eps figures, Phys. Rev. B, to appea

Photoactivity of Immobilized Titanium Dioxide (TiO2 ) in Lindane Degradation

Introduction and study objectives: Lindane is a generic name for γ-hexachlorocyclohexane, one of the isomers from the group of Hexachlorocyclohexanes (HCH) [1]. Due to its neurotoxic activity, it had a very wide application, from agricultural to non-agricultural purposes. As a result of its lipophility, lindane can easily pass through the blood-brain barrier. The reason of his neurotoxicity is that it can interact with GABAA receptors and obstruct GABA neurotransmitter signaling in nervous system. People who have been exposed to lindane for a long time can experience serious health problems, such as: poor liver function, cardiac arrhythmias, and irregular menstruation. Due to its adverse health effect, lindane is classified as a “pregnancy category C” chemical [2]. It is also one of the Persistent Organic Pollutants (POPs) that were listed under the Annex A (elimination) of the Stockholm Convention with a specific exemption for use as a human health pharmaceutical [3]. The aim of this paper was the assessment of the immobilized titanium dioxide photocalytic properties in lindane degradation. Methodology: Spray pyrolysis method was used for a synthesis of thin titanium oxide films on the foils of the stainless steel [4]. The lindane solution was incubated with TiO2 and exposed to UV/VIS light. Aliquots were taken from the reaction mixture after 0, 2, 4, 6, 8, 10 and 12 hours. Lindane was extracted according to the EPA method 505 [5], and analyzed using an Agilent 7890A gas chromatograph (GC) connected to an electron capture detector (ECD). The GC was equipped with a Thermo Scientific™ TraceGOLD™ TG-5MT capillary column (60 m × 0.25 mm ID × 0.25 μm). The temperature program used for gas chromatography was: Initial heating temperature: 50 °C for 3 minutes, then heating at a rate of 30 °C/min to 210 °C for 20 minutes. Hydrogen with a flow rate of 60 mL/min was used as the carrier gas. Results and conclusions: Photoactivity of immobilized titanium dioxide in the degradation of lindane was measured as a percentage of lindane’s degradation compared to its initial concentration. The obtained results demonstrated that after two hours 45.32 % of lindane was degraded, while after twelve hours the percentage of degradation increased to 98.20 %. In this study we proved that the immobilized titanium dioxide can be used as a productive and fast photocatalyst for lindane photodegradation

Manual and Automated Determination of Glucose in Blood with Glucose Oxidase and Molybdate/Iodide as Redox Catalyst

Peer Reviewe

Risk assessment of trace element contamination in river sediments in Serbia using pollution indices and statistical methods: a pilot study

To effectively manage potential environmental and human health impacts of contaminated river sediments, it is important that information about the source (anthropogenic vs geogenic), variability and environmental risks associated with the contamination are well understood. The present study was carried out to assess the source and severity of contamination and to undertake a risk assessment for selected elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) in river sediments in Serbia. The estimate of the anthropogenic component of contamination was derived by determining the total element content and the background values for elements in sediments, and the severity of pollution was assessed by calculating a number of pollution indices including the contamination factor, the enrichment factor, the index of geoaccumulation, the ecological risk factor, the potential ecological risk index, the pollution load index, the combined pollution index, the modified degree of contamination and the toxic unit factor. This analysis indicates that river sediments in Serbia are primarily polluted with Zn, Cu and Cd. The most contaminated river systems are the Ibar, Pek, West Morava and Great Morava rivers. Mining activities were found to have a significant influence on sediment. Multivariate analyses suggested anthropogenic origins for Pb, Zn, Cd, As, Ni and Cu, whilst Fe, V, Mn, Co and Cr appear to have a mixed origin (both lithogenic and anthropogenic sources). A geochemical approach, with a calculation of pollution indices and statistical methods, is recognised as useful for the risk management of trace elements in sediments around the world.Sanja Sakan, Gordana Dević, Dubravka Relić, Ivan Anđelković, Nenad Sakan, Dragana Ðorđevi