The corrosion and passivation behaviour of molybdenum thin films obtained by Physical Vapor Deposition (PVD) was investigated in aerated chloride and sulfate solutions at different pH values. Open circuit potential (ocp) measurements, polarisation experiments and electrochemical impedance spectroscopy (EIS) were employed. The experimental results suggest that the metal surface is covered by a passive film; however, corrosion still occurs. For the samples assessed during the current research, the acidic electrolytes tended to be less corrosive; however, a limited passive region was associated with the most basic sulfate or chloride solution. The effect of the pH was found to be more pronounced than the effect of the ion (chloride or sulfate).

This paper presents a mathematical model describing the change in the capacitance of both single and multilayer organic coatings exposed to a wet environment. The indication is that the capacitance technique can successfully be employed to monitor, in situ, the absorption of water through single-layer organic coatings for values of equilibrium water uptake to a maximum of 5% by volume. In addition, this model indicates a relationship for dUn /d5/ t ,where C is the coating capacitance and t is the time of exposure to the environment, that can be used to rank different single-layer coatings. Conversely, no quantitative correlation between mass uptake and coating capacitance was found for a multilayer coating system, even for low values of water uptake. Although, at face value, these findings suggest that this technique may be inapprepriate for in situ monitoring of water absorption in such complex systems, a comparison between gravimetric and capacitance data indicates that useful qualitative information may still be generated by the use of the latter technique.

Significance and Impact of the Study: The oral cavity of snakes sampled harboured a wide range of bacteria. Our results suggest that people who come in contact with snakes could be at risk of infection and should follow proper hygiene practices when handling these reptiles. AbstractThis study was aimed at evaluating the oral bacterial flora of 60 Python regius kept as pets by culture and biochemical methods. All isolates were also submitted to antimicrobial susceptibility testing using the disc diffusion method. The oral cavity of snakes sampled harboured a wide range of Gramnegative bacteria mainly constituted by Pseudomonas spp., Morganella morganii, Acinetobacter calcoaceticus, Aeromonas hydrophila, but also by Salmonella spp. Staphylococcus spp. was the commonest Gram-positive isolates, and various anaerobic Clostridium species were also found. The most effective antimicrobial agents were enrofloxacin and ciprofloxacin, followed by doxycycline and gentamicin. IntroductionIt is estimated that about 640 000 live reptiles are traded annually worldwide (Dipineto et al. 2012). Regarding snakes, there are over 2900 species in the world and a variety of snake species have enjoyed increasing popularity as pets during the last few years (Mitchell 2009). The most common, by far, are the colubrids, boids and python. However, although this increasing popularity is positive for veterinarians and herpetoculturists interested in the captive care and management of these animals, it has also caused increased concerns among public health officials because of the zoonotic potential (e.g. Salmonella) associated with these animals. Bacterial diseases of reptiles are occasionally caused by primary pathogens but often are the result of an immunocompromising condition, such as inappropriate temperatures, humidity or enclosure hygiene (Chinnadurai and Devoe 2009).The oral flora of snakes comprises a wide range of aerobic and anaerobic micro-organisms, especially the faecal Gram-negative rods, because their prey usually defecate while being ingested (Garg et al. 2009). Studies on the bacterial flora in snake's mouth have been undertaken worldwide (Blaylock 2001;Shek et al. 2009), but for Italy, specific data are lacking. The present study was therefore aimed at evaluating the oral bacterial flora of Python regius, one of the most popular snake species kept as pet worldwide. Results and discussionThe oropharynx of the P. regius checked in the present study contained a wide range of bacteria mainly represented by Gram-negative bacteria as proven by Gram staining. In particular, on each smear was visualized a prevalence of 80% for Gram-negative bacteria vs a prevalence of 20% for Gram-positive bacteria. Among Gram-negative isolates, Pseudomonas spp., identified as Ps. aeruginosa (n = 42) and Ps. putida (n = 9), were the commonest micro-organism (85%) followed by Morganella morganii (75%), Acinetobacter calcoaceticus (40%) and Citrobacter freundii (40%). Other important Gramnegative pathogens included Aeromonas hydrophila (30%) and Prot...

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In the past few years there has been increased interest in molybdenum thin films, which are commonly prepared by magnetron sputtering. There is a variety of novel applications of molybdenum such as, for example, components for soft X-ray optics based on Mo/Si multi-layers, the back contact in thin film solar cells, NO gas detection, and microelectronics. Molybdenum is, also, widely used as an alloying addition in stainless steels to facilitate the formation of the passive film and to improve resistance to pitting attack. Its corrosion behaviour is complex and many aspects still need to be clarified. During this study, the corrosion behaviour of the PVD-Mo thin film immersed in aerated sulfate and chloride solutions at 85 8C was investigated with both polarization and electrochemical impedance spectroscopy (EIS) measurements. It is apparent that the Mo thin film exhibits increased susceptibility to corrosion in more alkaline environments.