Experimental and numerical analysis of the influence of cable tray arrangements on the resulting mass loss rate and fire spreading

In the context of industrial buildings and power plants, electrical installations and cable trays represent a main fuel load and a potential initial fire source due to possible short circuits or comparable malfunction. Furthermore, a fire can spread from one tray to additional trays mounted above and/or horizontally on one tray. Because of the high significance of cable fires, several research projects have been carried out, investigating the fire behaviour of cables from small‐scale tests, eg, the cone calorimeter, up to large‐scale tests, analysing complete cable tray constructions. The goal of the work presented in this paper is the extension of the knowledge regarding the influence of geometrical parameters like the packing density and tray distance on the burning behaviour and fire spread of cable tray installations. The results are considered, together with test results from the literature, to quantify the main physical parameters describing the burning behaviour. In a next step, the general applicability of these parameters as input data for the parametrization of the source term of numerical simulations is shown. The test results show that the burning behaviour and the fire spreading highly depend on the cable arrangement of the cables on the cable tray, in combination with other boundary conditions. By applying the results as input for a fire simulation, the mass loss rate is considered appropriately.     

Analysis of Damage on the Streptococcus mutans Immersed in Ozonated Water: Preliminary Study for Application as Mouth Rinse

Ozonated water has been demonstrated to induce significant results in terms of the elimination of microorganisms. The present study assessed the damage to Streptococcus mutans after exposure to ozonated water; the ozone generator was adjusted to provide an outlet concentration of 60 mg/L, the samples were submitted to different ozonation times 1, 2, 4, 6, and 10 mi. Scanning electron microscopy and atomic force images were obtained to identify damage to the bacteria, followed by reactive oxygen species (ROS) evaluation and microbial viability. The results showed a significant reduction in viability and the images evidenced the generation of gaps on the microbial wall and surface layer alterations. Ozone can induce significant damage to S. mutans, thus suggesting that the use of ozonated water to prevent carious lesion formation is extremely promising.     

Anti-fingerprints fluorinated coating for anodized titanium avoiding color alteration

In this study amorphous fluorinated coatings applied to anodized titanium surface have been investigated. A copolymer between tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole (AD60) and two perfluoropolyether containing ammonium phosphate (F10) or triethoxysilane (S10) functionalities have been tested. To estimate the color alteration of the anodized titanium surfaces due to the application of the coatings, spectrophotometric analyses have been made. Water and n-dodecane contact angles as well as apparent surface energy have been evaluated. Ellipsometry and atomic force microscopy data have been used to measure the thickness of the fluorinated coatings. A tailored mechanical preliminary test has also been explored to evaluate the adhesion of the coatings on the anodized titanium surface. The resistance to surface soiling with castor oil was also preliminarily investigated. The fluorinated coating tested on anodized titanium showed a low apparent surface energy and high chromatic aspect conservation, this is particularly evident for the titanium anodized coated with triethoxysilane functionalities fluoropolymers S10.     

Influence of the chemical structure of PUR prepolymers on thermal stability

The thermal stability of adhesives for load-bearing construction has been one of their key parameters since engineered wood products were introduced in timber construction. In the case of one-component moisture-curing polyurethane (1C PUR) adhesives, knowledge about relationships between their chemical structure and the resulting bonding properties is limited, especially under high-temperature conditions. In this study the structure-property relationships of 1C PUR prepolymers were analyzed in the temperature range from 20 to 200 °C by means of mechanical and rheological tests. NCO-terminated urethane prepolymers were prepared from systematically varied MDI and polyether mixtures. The structural parameters investigated were the urea and urethane group content, cross-link density, ethylene oxide content and the adjustment of functionality via NCO or polyether component. Bonded wood joints were tested for their tensile shear strength and polymer films were analyzed by means of DMA and DSC. The results revealed a significant influence of hard segment content and cross-link density on the thermal stability of the prepolymers. Not all parameters that affect the film properties significantly influence bonding.     

GC/EI-MS Determination of the Diastereomer Distribution of Phytanic Acid in Food Samples

Phytanic acid (3,7,11,15-tetramethylhexadecanoic acid) is a branched-chain fatty acid, produced by bacteria by means of oxidation and biohydrogenation of the chlorophyll side chain phytol (3,7R,11R,15-tetramethylhexadec-2-en-1-ol). The later reaction generates to a new stereogenic center on C-3 which can be both 3R- or 3S-configured. Thus, two diastereomers (3S,7R,11R,15- and 3R,7R,11R,15-phytanic acid) are naturally produced. In this study we examined the diastereomer composition of phytanic acid in terrestrial and marine food samples. Phytanic acid was transferred into its methyl ester which was analyzed by GC/MS in the selected ion monitoring mode. The first eluted diastereomer in the samples was tentatively identified as 3S,7R,11R,15-phytanic acid. The marine samples were clearly dominated by 3S,7R,11R,15-phytanic acid whose abundance was higher in marine mammals than in fish. Milk from one organic cow collected over a period of 30 days showed lower proportions of 3S,7R,11R,15-phytanic acid than milk from one cow raised with conventional feed. The difference between organic and conventional dairy products (cheese and butter) was not as pronounced as in milk. Milk samples from other mammals (goat, sheep, mare, camel, moose, and human) also showed an excess of 3S,7R,11R,15-phytanic acid except for camel and moose milk.     

Simulation and optimization of a flow battery in an area regulation application

Flow batteries have the potential to provide ancillary grid services such as area regulation. In this paper, a hypothetical 2 MW flow battery is simulated in an area regulation application to find the optimal energy-to-power ratio that maximizes the net present value (NPV) of a 10 year project based on a range of installation costs. Financial and operational results are presented, and candidate battery chemistries are discussed. A simplified model of battery installation costs (dollars per kW h) resulted in a positive NPV for installation costs below $500 kW⁻¹ h⁻¹. For installation costs between $500 kW⁻¹ h⁻¹. For installation costs between 300 and $500 kW⁻¹ h⁻¹, an optimal energy-to-power ratio is 1.39. The traditional advantage of decoupling power and energy capacity may not be realized in area regulation; therefore hybrid flow batteries may be more appropriate. Zinc-bromine and iron-chromium chemistries might fit well with this application, along with lower-cost flow battery chemistries in the future.     

Electro-dissolution of 30Nb–Ti alloys in methanolic sulfuric acid—Optimal conditions for electropolishing

The electro-dissolution behaviour of a (30 at.%) Niobium–Titanium (NbTi) alloy in non-aqueous methanolic sulfuric acid solution using the rotating disc electrode (RDE) was ascertained. The optimal condition for electropolishing and the mechanism were proposed. The influence of the rotation rate, process temperature and sulfuric acid concentration on the dissolution kinetics was investigated. The dissolution rate (limiting current) increases linearly with increase in rotation rate and follows a Levich behaviour confirming a mass transport controlled process. The temperature dependence in terms of Arrhenius plot renders an activation energy value of E_a = 16.1 kJ mol⁻¹ for the process. The dissolution rate shows a strong dependence on the sulfuric acid concentration (1 M, 3 M and 5 M). Higher sulfuric acid concentrations lead to decreased dissolution rates (limiting current). The dissolution process is mass transport controlled in all concentrations of sulfuric acid. From an electrochemical perspective, a 3 M sulfuric acid was chosen as optimum owing to better controllability of the material removal rate. The dissolving ions are the probable rate limiting species, indicating a compact salt-film mechanism. The average root mean square (RMS) roughness value for an electropolished surface was approximately 10 nm, which is significantly lower than a mechanically polished surface.