Mild Effects of Sunscreen Agents on a Marine Flatfish: Oxidative Stress,Energetic Profiles,Neurotoxicity and Behaviour in Response to Titanium Dioxide Nanoparticles and Oxybenzone

UV filters are potentially harmful to marine organisms. Given their worldwide dissemination and the scarcity of studies on marine fish, we evaluated the toxicity of an organic (oxybenzone) and an inorganic (titanium dioxide nanoparticles) UV filter, individually and in a binary mixture, in the turbot (Scophthalmus maximus). Fish were intraperitoneally injected and a multi-level assessment was carried out 3 and 7 days later. Oxybenzone and titanium dioxide nanoparticles induced mild effects on turbot, both isolated and in mixture. Neither oxidative stress (intestine, liver and kidney) nor neurotoxicity (brain) was found. However, liver metabolic function was altered after 7 days, suggesting the impairment of the aerobic metabolism. An increased motility rate in oxybenzone treatment was the only behavioural alteration (day 7). The intestine and liver were preferentially targeted, while kidney and brain were unaffected. Both infra- and supra-additive interactions were perceived, with a toxicodynamic nature, resulting either in favourable or unfavourable toxicological outcomes, which were markedly dependent on the organ, parameter and post-injection time. The combined exposure to the UV filters did not show a consistent increment in toxicity in comparison with the isolated exposures, which is an ecologically relevant finding providing key information towards the formulation of environmentally safe sunscreen products.     

Epoxy–quartz based composites for use in polishing crowns of ornamental rocks

The present work develops the processing and abrasive tests of composites based on the system epoxy–quartz. The objective was to evaluate its technological application as abrasive crowns for the polishing of ornamental rocks, usually made based on the magnesia cement composite SOREL-SiC. Composites were produced with composition epoxy–(70, 75, 80, 85 and 90) % weight of quartz. The compounds were mixed and cured with a catalyst. The composites were submitted to abrasive wearing tests and compressive tests, simulating the polishing operation of ornamental rocks. Surface finishing produced in an ornamental rock and the weight loss of the crowns were evaluated and compared to those obtained for commercial magnesia cement SOREL-SiC. The work concludes for the positive technical viability of this new composite epoxy-silica for use in the ornamental rock industry.     

Decay of pavement mortar due to thaumasite formation

BACKGROUND: This paper discusses the formation of thaumasite in the mortar sub‐flooring used as a base material for laying tiles, and the influence of this mineral in relation to deterioration of building materials. An investigation of a mortar sub‐flooring constructed with dolomitic limestone sand with high sulfate content used to settle a ceramic pavement was carried out. RESULTS: The mortar sub‐flooring underwent an important deterioration process due to the formation of expansive compounds in the environmental conditions of temperature and humidity of the installation area in Murcia (Spain). Expansion appeared essentially at the interface between the ceramic tiles and the mortar sub‐flooring, an area consisting primarily of cement paste. CONCLUSION: Materials present in the soft pulpy mass were examined by X‐ray diffraction and scanning electron microscopy with energy‐dispersive X‐rays. The presence of thaumasite was detected, which had been formed under conditions of temperature higher than temperatures reported in the literature and with a high degree of humidity. Copyright © 2008 Society of Chemical Industry     

Carbon fiber/ceramic matrix composites: processing,oxidation and mechanical properties

Ceramic matrix composites (CMC) have been considered in the last two decades to be alternative materials for highly demanding thermo-structural applications. Pre-ceramic polymers offer significant advantages for manufacturing these composites by the polymer impregnation method. In the present work, carbon fiber/silicon oxycarbide (C/SiC _x O _y ) composites were obtained by controlled pyrolysis of carbon fiber/bridge polysilsesquioxane composites (COMPOSITE 1) followed by infiltration/pyrolysis cycles with a polycyclic silicone network. The polysilsesquioxane showed high wettability and adhesion on the carbon fiber surface. An improvement of the thermo-oxidation resistance and a reduction of the porosity as a function of the number of polycyclic silicone infiltration cycles were observed. An extra improvement in the thermo-oxidation protection was found when the C/SiC _x O _y composite was coated with a poly(phenylsilsesquioxane) layer (COMPOSITE 2). Shear properties for the composites showed a dependence on the nature of the matrix. The average in-plane shear strength and the shear modulus were 44.2 ± 1.9 MPa and 2.2 ± 0.5 GPa for the polymeric matrix composite (COMPOSITE 1), respectively. For the ceramic matrix composite (COMPOSITE 2) the values were 14.2 ± 4.1 MPa and 15.0 ± 2.0 GPa, respectively. The properties of the latter composite were also governed by the microstructure of the ceramic matrix.     

V International Conference and Exhibition “Computer-Aided Design and Manunfacture Product Data Manager (CAD/CAM/PDM-2005)” October 25–27, 2005

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V International Conference and Exhibition “Computer-Aided Design and Manunfacture Product Data Manager (CAD/CAM/PDM-2005)” October 25–27, 2005     

Interesterification of tallow and sunflower oil

The objective of this study was to manufacture a shortening using chemical interesterification (IT) of tallow-sunflower oil blends to replace fish oil in the present formulation, which is now in short supply in Chile. The significant variables of the IT process were obtained by 2⁴⁻¹ fractional factorial design. The proportion of tallow (T) in the blend, catalyst concentration, and reaction temperature had a significant effect on the melting point (mp) (P≤0.05). IT of tallow and sunflower oil blends (90∶10 and 70∶30) diminished the mp, dropping point, and refractive index compared to tallow. However, a noninteresterified 90∶10 blend mp was not significantly different from tallow. IT produced a solid fat content (SFC) profile of IT90∶10 blend that was appropriate for use in shortenings for the baking industry. Blending and IT of the 90∶10 blend increased the melting profile of the tallow and the melting range from −40 to 60°C while the endotherms of the middle-melting triacylglycerols (TAG) decreased. The IT90∶10 blend hardnesswas 70% lower than tallow hardness, and the crystal network was composed of large spherulites in a network. IT resulted in an appropriate method to improve physical properties of tallow, whereas blending did not significantly modify it. The interesterification changed the SFC profile of IT90∶10, giving a more appropriate shortening for use in the baking industry.     

Phosphate adsorption on chemically modified sugarcane bagasse fibres

Integral sugarcane bagasse fibres of about 2 cm length that were pre-treated for removal of greases and sugars were carboxymethylated on their surface, retaining about 20% of impurities (as insoluble material and water). The fibres were doped with Fe²⁺ ion, by dipping in aqueous iron chloride solutions of different concentrations. This material was used to remove phosphate from water. Thermal analyses (differential scanning calorimetry – DSC) and infrared spectroscopy – FTIR show the occurrence of important changes on carboxymethylated fibres after incorporation of Fe²⁺ and PO₄^3-. Non-carboxymethylated fibres, also treated with the iron solutions, also showed a good level of capture of phosphate from an aqueous solution. The chemical modification increases Fe²⁺ ion adsorption on the fibre surface, increasing the efficiency of phosphate adsorption. Apparently, the process of modification, without incorporation of Fe²⁺, also improves phosphate retention. When about 4% of iron is adsorbed on the fibres, 97% of phosphate is captured on the carboxymethylated material and 94% on the non-carboxymethylated material. The absorption data fit both the Langmuir and Freundlich isotherm. When quantified by measuring the monolayer adsorption in the Langmuir isotherm model, the presence of Fe²⁺ ions on the surface fibres increases the phosphate adsorption capacity by about 45%. Our results (Q max = 152 mg/g) are far superior or in the same order of magnitude, when compared with literature data, with the advantage be the raw material, waste of biomass, only somewhat changed chemically and even after the modifications compose materials harmless to the environment.     

Semiconductor to metal transition in degenerate ZnO: Al films and the impact on its carrier scattering mechanisms and bandgap for OLED applications

Temperature dependent Hall measurements revealed that ionized impurity scattering was the dominant mechanism in sputter deposited, degenerate, aluminum doped zinc oxide (AZO) films up to ~530 nm thickness, and a semiconductor to metal transition was observed when thickness was further increased. With the increase in film thickness, the mobility and conductivity also increased from 6.70 to 18.7 cm² V^?1 s^?1 and 1.83 × 10²–8.28 × 10² (Ω cm)^?1, respectively. However, this was accompanied by a larger than 0.2 eV Burstein–Moss blue-shift of the interband absorption edge determined from absorption spectra. The movement of the Fermi level further into the conduction band that accompanies the Burstein–Moss shift results in a corresponding workfunction decrease of the films. This means that the interface barrier for hole injection in anode applications such as organic light emitting diodes (OLEDs) becomes larger, which translates into higher turn-on voltages and lower current and power efficiencies compared to indium tin oxide anodes. It is suggested that improving conductivity through mobility increases, and increasing workfunction through surface functionalization may improve the prospects of AZO films in OLEDs and other applications where in addition to conductivity and transparency, workfunction is also critical.     

A near-optimal routing and dimensioning algorithm for dynamic WDM rings

In this paper a novel algorithm which jointly solves the problems of routing and dimensioning in dynamic WDM rings is proposed. The algorithm is simple, very fast (processing time <1 s) and applicable to rings of any size. After applying the algorithm to rings of 6–20 nodes, it was found that it outperformed the best proposal to date. In the cases where the optimal solution could be obtained by solving an ILP (Integer Linear Programming) model, the algorithm proposed here obtained exactly the same results. These facts make the proposed method the best solution to date for the routing and dimensioning of dynamic WDM rings, the most popular topology in metropolitan networks.