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We investigated the relationships between the opacity and the physico-chemical characteristics of fish otoliths and more specifically their aragonite and organic fractions. The analysis of these two fractions on otolith macrostructures was performed using Raman microspectrometry on both translucent and opaque zones of otoliths of pollock (Pollachius virens) and European hake (Merluccius merluccius). The magnitude of the Raman signatures of the aragonite and organic fractions were strongly correlated to otolith opacity with maxima in translucent zones. Opacity models, built from Raman signatures, successfully predicted the observed opacity for both species. A partial decorrelation of different aragonite signatures between translucent and opaque zones was revealed and discussed in terms of organisation (size, orientation) of aragonite crystals. Two categories of organic signatures with opposite effects on the opacity were identified, suggesting differences in organic compounds and (or) variations in their relative quantities. These original contributions provided new insight for understanding otolith biomineralization mechanisms as well as for interpreting and discriminating otolith macrostructures. Nous avons etudie les relations entre l'opacite et les caracteristiques physico-chimiques d'otolithes de poisson, en particulier leurs fractions minerale et organique. L'analyse de ces deux fractions dans les macrostructures d'otolithes a ete effectuee par micro-spectrometrie Raman sur des zones translucides et opaques d'otolithes de lieu noir (Pollachius virens)etde merlu (Merluccius merluccius). La magnitude des signatures Raman des fractions minerale et organique etait fortement correlee a l'opacite de l'otolithe, les maxima etant observes dans les zones translucides. Des modeles d'opacite etablis a la lumiere des signatures Raman ont predit avec succes l'opacite observee pour les deux especes. Une decorrelation partielle de differentes signatures d'aragonite entre les zones translucides et opaques est mise au jour, suggerant une relation avec l'organisation des cristaux d'aragonite (taille, orientation). Des contributions distinctes de deux categories de signatures organiques peuvent etre interpretees comme associees a des quantites et (ou) des proprietes differentes des composes organiques contenus dans les deux structures etudiees. Ces resultats contribuent a ameliorer la comprehension des mecanismes de biomineralisation des otolithes et aider a l'interpretation et la discrimination des macrostructures d'otolithes. [Traduit par la Redaction], Introduction Otoliths are calcareous concretions in the inner ears of fish, consisting of calcium carbonate, mainly in the form of aragonite (90%-99% of the total otolith mass) and an organic [...]

A new polymeric biocide polyhexamethylene guanidine (PHMG) molybdate has been synthesized. The obtained cationic polymer has limited water solubility of 0.015 g/100 mL and is insoluble in paint solvents. The results of acute toxicity studies indicate moderate toxicity of PHMG molybdate, which has a median lethal dose at 48 h of 0.7 mg/L for Daphnia magna and at 96 h of 17 mg/L for Danio rerio (zebrafish) freshwater model organisms. Commercial ship paint was then modified by the addition of a low concentration of polymeric biocide 5% (w/w). The painted steel panels were kept in Dnipro River water for the evaluation of the dynamics of fouling biomass. After 129-d exposure, Bryozoa dominated in biofouling of tested substrates, forming 86% (649 g/m2) of the total biomass on control panel surfaces. However, considerably lower Bryozoa fouling biomass (15 g/m2) was detected for coatings containing PHMG molybdate. Dreissenidae mollusks were found to form 88% (2182 g/m2) of the fouling biomass on the control substrates after 228 d of exposure, whereas coatings containing PHMG molybdate showed a much lower biomass value of 23.6 g/m2. The leaching rate of PHMG molybdate in water was found to be similar to rates for conventional booster biocides ranging from 5.7 μg/cm2/d at the initial stage to 2.2 μg/cm2/d at steady state. Environ Toxicol Chem 2017;36:2543-2551. © 2017 SETAC [ABSTRACT FROM AUTHOR]

The proton/lithium exchange property of the lithium lanthanum titanate Li(0.30)La(0.57)TiO(3) (named LLTO) is shown to occur at room temperature under ambient air. The (1)H and (7)Li MAS NMR, TGA analysis and IR spectroscopy techniques are used to probe reaction mechanisms. XRPD analysis gives evidence of the topotactic character of this exchange reaction. As for exchange in aqueous solution, it is shown that Li(0.30)La(0.57)TiO(3) is able to dissociate water on the grain surface and then to exchange H(+) for Li(+) into the perovskite structure. Lithium hydroxide is then formed on the grain surface and afterwards reacts with CO(2) contained in air to form Li(2)CO(3). It is shown that this mechanism is reversible. When the aged sample (aging in air for 5 months at room temperature) is annealed at 400 degrees C for two hours, the initial LLTO sample is totally recovered, a mass loss is observed and the carbonate signal in IR spectra disappears, demonstrating the reversibility of the carbonation reaction process.