Misinterpretation of ISO 4049 standard recommendations: Impact on Young's modulus and conversion degree of dental composites.

OBJECTIVES: The purpose of this study was to study the effects on Young's modulus and conversion degree of variations in polymerization conditions during the 3-point bending test of composite samples in accordance with the ISO 4049 standard. METHODS: Three nanocomposites were used in the 3-point bending test based on the conditions described in the ISO 4049 standard. Samples of 2 mm × 2 mm x 25 mm were fabricated and tested with a different number of irradiation points and irradiation time. Conversion degree of the samples were also measured by micro-Raman spectroscopy and correlated with the Young's modulus values obtained for each one. RESULTS: The variations in curing protocol during specimen's realization influenced the Young's modulus and degree of conversion of all composites. These two properties correlated well. The ISO 4049 standard defines the conditions for performing the properties tests of composites to allow reproducibility and comparison of different studies. Concerning the 3-point bending test, even a minimal change in the state causes differences in the results obtained. The standard should thus clarify the tools that can be used when producing samples in order to minimize discrepancies. SIGNIFICANCE: The influence of the parameters surrounding the design of the samples should be controlled and defined so as not to include bias in the studies carried out. This will allow literature studies to be compared with more accuracy.

Dye residues in aquaculture products: Targeted and metabolomics mass spectrometric approaches to track their abuse.

The aim of the study was to initiate an exhaustive strategy of control by implementing both targeted and non-targeted metabolomics approaches. A LC-MS/MS method including an oxidative step for most of dyes was developed and validated to target the analysis of 14 residues belonging to different families of dyes. The method was suitable for the quantitative confirmation of 13 dyes at low ppb levels. The metabolomics approach objective was to compare fingerprints between farmed fish treated with malachite green and farmed fish treated with victoria pure blue bo. Analytical information on modifications in the metabolome of muscle, liver and plasma was exploited by HRMS following by multivariate statistics and revealed some direct or endogenous metabolites among relevant mass features contributing to the constructed models. These two approaches, either appropriate biomarkers either enlarged targeted dyes are explored concomitantly to help improving the strategy for tracking new illegal practices in aquaculture.