242 research outputs found
Bioluminescent bacteria as bioindicators in environment
No full textWith the developments in science of the last decades the environmental consciousness has greatly increased. In every place where man has an influence on the environment which is not a naturally occurring one should be surrounded with procedures to lower it’s environment impact.
In vivo luminescence is a sensitive indicator of xenobiotic toxicity: if noxious substances are present, the bacterial luminescence decreases proportionally to their concentration.
References:
Girotti, S., Ferri, E.N., Bolelli, L., Sermasi, G., Fini, F. Applications of bioluminescence in analytical chemistry. In: “Chemiluminescence in Analytical Chemistry”, A.M. Garcia-Campaña, W.R.G. Baeyens, Eds. New York, Marcel Dekker, 247-284, 2001.
S.Girotti, L. Bolelli, A.Roda, G.Gentilomi, M.Musiani. “Improved detection of toxic chemicals using bioluminescent bacteria”. Anaytica Chimica Acta, 471, 113-120, 2002
Replacement of hard chromium plating by thermal spraying - Problems, solutions and possible future approaches
No full textHeat treatment effects on the corrosion resistance of some HVOF-sprayed metal alloy coatings
No full textThe present study evaluates the effects of a 600 °C, 1 h heat treatment on the corrosion resistance of threeHigh Velocity Oxygen Fuel (HVOF) flame-sprayed alloy coatings: a Co–28Mo–17Cr–3Si (similar to Tribaloy-800) coating, a Ni–20Cr–10W–9Mo–4Cu–1C–1B–1Fe (Diamalloy-4006) coating and a Ni–32Mo–16Cr–3Si–2Co (similar to Tribaloy-700) coating. Electrochemical polarization tests and free corrosion tests wereperformed in 0.1 M HCl aqueous solution. The corrodkote test (ASTM B380-97R02) was also performed, toevaluate the coatings qualitatively. The heat treatment improves the corrosion resistance of the Co–28Mo–17Cr–3Si coating and of the Ni–20Cr–10W–9Mo–4Cu–1C–1B–1Fe coating by enhancing their passivationability. The precipitation of sub-micron sized secondary phases after the treatment may produce galvanicmicrocells at intralamellar scale, but the beneficial contribution provided by the healing of the very small but dangerous interlamellar defects (normally present in thermal spray coatings but not detectable usingordinary scanning electron microscopy) prevails. The effect on Ni–32Mo–16Cr–3Si–2Co coatings is moreambiguous: its sensitivity to crevice corrosion is worsened by the heat treatment
HVOF-sprayed WC-CoCr coatings on Al alloy: Effect of the coating thickness on the tribological properties
No full textThe microstructure, the micromechanical properties, the wear behaviour and the impact resistance of WC-CoCr cermet coatings, deposited onto an aluminium alloy substrate by High Velocity Oxygen-Fuel (HVOF) flame-spraying, were examined as a function of the coating thickness, which was varied between 50 mu m and 150 mu m by performing different numbers of scans of the HVOF torch in front of the substrate. The coatings became denser and significantly harder as the number of torch scans increased: the analysis of single WC-CoCr splats by combined SEM and Focused Ion Beam (FIB) techniques enabled the interpretation of the mechanisms underlying this phenomenon. In accordance to such densification, the sliding wear resistance increased with the number of torch scans, as abrasive grooving and brittle failure mechanisms were progressively suppressed. The resistance to cyclic impact was also enhanced. In comparison to anodised films, the WC-CoCr coatings appeared much more resistant against wear and cyclic impact; specifically, three torch scans seem enough to produce a coating having suitable characteristics. (C) 2009 Elsevier B.V. All rights reserved
Alkaline water better than plain water? A critical review
No full textPE2. ALKALINE WATER BETTER THAN PLAIN WATER? A CRITICAL REVIEW
Emanuele MORGANTI,1 Luca BOLELLI,1 Giuseppe NOVELLI,2
Chris FREEMAN,2 Stefano GIROTTI1
1Department of Pharmacy and Biotechnology FaBiT, Via San Donato 15, Alma Mater Studiorum - Università di Bologna, Bologna,40127, Italy
2CULLIGAN ITALIANA SPA, Cadriano di Granarolo Emilia, Bologna, 40057, Italy
Water is the basic element of living beings. No other substance is more important for human body than water. In fact, in the reference man, 60% of body weight (BW) (about 45 L) is represented by total body water (TBW) [1]. Some people believe that alkaline water can help to drain toxins more efficiently than regular tap water, leading to better health and fitness. Alkaline water has a higher pH level than plain water. Proponents say that it can neutralize acid in bloodstream, boost the metabolism and help the body to absorb nutrients more effectively. Some even say that alkaline water can help prevent diseases and slow the aging process. An investigation in the scientific literature has been done to verify these claims. The main consideration that could be done is that the alkalinity in ionized water is due to the sodium hydroxide formed during electrolysis if salt is the electrolyte in the water. Most alkaline water representatives do not like to admit this, but when the sodium hydroxide enters the stomach, it is immediately neutralized by the strong stomach acidity back into water and salt ions. There is no reason to expect that the water formed when the alkaline hydroxide ion is neutralized will retain any special characteristics (even if it had some in the beginning) or that dissolved salt, which results from the neutralization process, will have any special properties when it is absorbed. The alkalinity level of the incoming water relative to the acidity of the stomach acid and to the pH the body's well-buffered blood is negligible. This means that there would be almost no resulting effect on pH of the body. The EFSA (European Food Safety Authority) does not authorize any health assertion about alkaline water because is not based on solid scientific data [2]. In conclusion, at this moment, there is no credible evidence in standard medical or scientific literature to support claims that alkaline water has any greater health effects or health benefits than drinking regular water.
[1] L. Petraccia et al., Clinical Nutrition 25 (2006) 377–385.
[2] EU Register on nutrition and health claims: http://ec.europa.eu/nuhclaim
Wear and corrosion behaviour of HVOF-sprayed WC-CoCr coatings on Al alloys
No full textWC-CoCr coatings were HVOF-sprayed onto an AA6082T6 substrate. Thickness values between 50 Î1⁄4n and 150 Î1⁄4n were produced by stepwise increase of the number of torch scans. This increase makes the coatings not only thicker, but also denser. This is due both to peening effects and by modifications to the splat formation mechanism, investigated by FIB. Thanks to such densification, the hardness, the wear and impact resistance and the corrosion protectiveness of the layers increase with the number of torch scans. The largest improvement occurs from 2 to 3 torch scans. These coatings were also compared to anodized films: cermets have superior wear and impact resistance but offer less corrosion protection. Copyright © 2009 ASM International® All rights reserved
Mechanical strength and wear resistance of protective coatings applied by Fluidized Bed (FB)
No full textThis study deals with the interrelation between the thermo-rheological behaviour of an epoxy-based powder coating system and its mechanicalstrength and wear endurance.Matte-finish protective polymeric films deposited by electrostatic fluidized bed (EFB) and conventional hot dipping fluidized bed (CHDFB)on metal substrates were examined. First, the analysis of thermo-rheological behaviour of the epoxy-based powder coating system was detailed.Secondly, the adhesion strength and wear endurance of polymeric films was related to the thermo-rheological behaviour of the starting materialformulation. Finally, based on the experimental data, generalized scratch and wear map, in which the overall mechanical performance of thematte-finish polymeric films at different curing levels is reported, was usefully provided.The experimental findings lead to further advances in the understanding of the mechanisms involved in the establishment of the overall mechanicalperformances of fluidized bed (FB) deposited polymeric films. They also provide important indications for the settings of curing parameters orpreheating temperatures in FB coating processes as well as for the development of new powder coating formulations
Improving Fast Charging‐Discharging Performances of Ni‐Rich LiNi0.8Co0.1Mn0.1O2 Cathode Material by Electronic Conductor LaNiO3 Crystallites
No full textFast charging‐discharging is one of the important requirements for next‐generation high-energy Li‐ion batteries, nevertheless, electrons transport in the active oxide materials is limited. Thus, carbon coating of active materials is a common method to supply the routes for electron transport, but it is difficult to synthesize the oxide‐carbon composite for LiNiO2‐based materials which need to be calcined in an oxygen‐rich atmosphere. In this work, LiNi0.8Co0.1Mn0.1O2 (NCM811) coated with electronic conductor LaNiO3 (LNO) crystallites is demonstrated for the first time as fast charging‐discharging and high energy cathodes for Li‐ion batteries. The LaNiO3 succeeds in providing an exceptional fast charging‐discharging behavior and initial coulombic efficiency in comparison with pristine NCM811. Consequently, the NCM811@3LNO electrode presents a higher capacity at 0.1 C (approximately 246 mAh g−1) and a significantly improved high rate performance (a discharge specific capacity of 130.62 mAh g−1 at 10 C), twice that of pristine NCM811. Additionally, cycling stability is also improved for the composite material. This work provides a new possibility of active oxide cathodes for high energy/power Li‐ion batteries by electronic conductor LaNiO3 coating
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