Use of polymer mats in series for sequential reactive barrier remediation of ammonium-contaminated groundwater: field evaluation

A pilot-scale field trial was undertaken to evaluate the potential of in situ polymer mats (installed in series) as permeable reactive barriers within a treatment wall remediation system to induce sequential bioremediation of ammonium-contaminated groundwater. The treatment wall consisted of 10 m wide impermeable wings on either side of a 0.75 m wide permeable reactive zone flow-through box. Two polymer mats were positioned in the flow-through box. The upgradient polymer mat within the flow-through box was used to deliver oxygen to induce bacterial nitrification of the ammonium to nitrite/nitrate as the groundwater moved past. The downgradient polymer mat delivered ethanol to induce bacterial denitrification of the nitrite/nitrate to produce nitrogen gas. The field trial was carried out at a near-shore location. Initially the flow-through box was left open; however, this resulted in substantial groundwater mixing, which inhibited sequential remediation. Once the flow-through box was in-filled with gravel, groundwater mixing was reduced, achieving a greater than 90% reduction in total N. Estimated first-order half-lives for nitrification and denitrification rates were 1.2 and 0.4 d, respectively. Field nitrification half-lives were approximately an order of magnitude greater than rates determined in large-scale columns using soil and groundwater from the site, while denitrification half-lives were similar. The results of this pilot-scale field trial indicate that sequential bioremediation of ammonium-contaminated groundwater at field scale is feasible using in situ polymer mats as permeable reactive barriers, although hydraulic conditions can be complex in such barrier systems.     

Core-annular flow in horizontal and slightly inclined pipes: Existence, pressure drops, and hold-up

An analysis of high viscosity oil/water flow in horizontal and slightly inclined pipe is presented. We propose experimental flow maps – in particular we focus on the core-annular flow pattern boundary – pressure drops, and oil hold-up measurements. Experimental data are used to validate some models present in literature. Since hold-up measurement in liquid–liquid systems is particularly challenging and, therefore, only few data are available in literature, they are analyzed and commented in detail. The slip ratio computed by hold-up data is also provided and analyzed.     

Use of silicon drift detectors for the detection of medium-light elements in PIXE

In order to fully exploit in PIXE the superior performance of silicon drift detectors especially for the detection of low- and medium-energy X-rays, avoiding in particular the negative effects of backscattered particles, we developed a custom spectrometer based on a 10 mm² chip with a thermoelectric Peltier cooler and home-designed front-end electronics, coupled to a weakly focusing polycapillary lens.This paper briefly describes the detector + lens assembly and reports the results of first tests carried out at an external beam line of the LABEC laboratory in Florence. Excellent energy resolution is achieved under real operating conditions in a PIXE run (measured FWHM at 1 keV is 81 eV with a count-rate of 480 cps) and also the lineshapes are very good (FW1/10M over FWHM ratio is 2.1). As a whole, our preliminary tests gave encouraging results and also helped to point out some aspects which it is worthwhile to investigate further (e.g. how X-ray peak intensity ratios may be affected by inaccurate lens alignment), in order to profit fully from such a good performance of the spectrometer.     

Audiovisual bounce-inducing effect: Attention alone does not explain why the discs are bouncing.

Two discs moving from opposite points in space, overlapping and stopping at the other disc's starting point, can be seen as either bouncing or streaming through each other. With silent displays, observers report the discs as streaming, whereas if a sound is played when the discs touch each other, observers report the discs as bouncing. The origin of the switch from streaming to bouncing response is not known yet. The sound either shifts perception toward that of an impact-elastic event (i.e., a bounce) or subtracts the attention that is necessary to perceive the discs as streaming. We used either impact-similar (abrupt amplitude attack, gradual decay) or impact-dissimilar sounds (gradual amplitude attack, abrupt decay) and found that the first sounds induce the bouncing response, whereas the latter, although as distracting as the first, render streaming and bouncing responses equally frequent at most. We interpret the audiovisual bouncing effect as resulting from attention subtraction, which raises the number of bounce responses in comparison with silent displays, and from perception, which further increments the number of bounce responses and turns the response into a strong bounce response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organo-silane coatings for AZ31 magnesium alloy corrosion protection

The protective performances of coatings formed by organo-silanes with a long alkyl chain for AZ31 magnesium alloy corrosion protection were evaluated by electrochemical techniques. The coatings were formed in hydroalcoholic baths of octyl- or octadecyl-trimethoxy-silane, and hydrolyzed at different pH values.

The coatings formed at all the pH by the lower homologue were always porous and scarcely protective. Those built by the higher homologue were more corrosion resistant and the best results were observed when octadecyl-trimethoxy-silane was hydrolyzed at pH 5: in this case a thick, scarcely defective, layer was formed and no evident corrosion attack was observed after 1000 h immersion in 0.05 M Na₂SO₄ solution.     

Hydrogeological features of a rocky massif to be used as a nuclear repository

The Sierra del Medio rocky massif is situated in the central west sector of a probably closed Cainozoic sedimentary basin. Sierra del Medio behaves as an area having a positive relief which receives rainfall and spreads it over the superficial smaller basins around. From the geological and geophysical points of view it is believed that the massif is separated from the adjacent basin water bearing formations by fractures belonging to the direct type. It is formed by Palaeozoic migmatites of granitic to tonalitic composition intruded by acidic, mesosilicic and basic dikes. Ectinite xenoliths can also be found. The different hydrogeological units in the rocky massif under study were defined preliminarily in geological, geophysical, mechanical and chemical detailed studies. Tentative isopiezometric curves are shown and geophysical profiles are analyzed.     

Crenotherapy in sports medicine: the state of the art

The existing relationship linking thermal and sport medicine has developed with time. This is shown by the established beneficial effects of thermal treatments (mineral waters, mud baths, balneotherapy, aerosol applications) in a wide range of sport and non-sport related injuries. The muscle fatigue syndrome is a condition particularly worrisome for sports practising individuals. This condition impairs the cardiovascular system, as well as hematologic, renal and gastrointestinal functions, acting via biochemical and metabolic modifications of the organism, which have effects also on the psyche of the subject. The treatment of this syndrome includes the use of specific mineral waters, which underscores that the correct hydration of the organisms is a precondition to achieve high performance levels. Traumas involving muscles and skeletal segments, and precocious arthrosis occur with higher frequency in sportsmen after continuous and intense stresses. Within the scope of rheumatology, mud-baths and balneotherapy have curative and rehabilitative potentials leading to a reduction, and often a disappearance, of pain with a faster recovery of the locomotory system. The gastrointestinal system is a target of psychic as well as physical stresses displaying symptoms or diseases which may be favourably addressed with the aid of mineral waters. This treatment has proved effective in secretory and motility dysfunctions of the biliary tree allowing a rapid functional recovery. Mineral water treatments are successfully employed in the treatment of urologic disturbance and ORL and dermatological pathologies, where local applications such as mud baths, balneotherapy, showers and aerosols, play a critical role.