Inmobilization of Zn(II) in Portland cement pastes. Determination of microstructure and leaching performance

The aim of this paper is to study the solidification/ stabilization potential of cementitious matrices on the immobilization of Zn(II) before its disposal into the environment by determining the mechanisms of interaction between the Zn(II) ions and the binder. The results of structural and mineralogical characterization of cement pastes formed with different amounts of immobilized Zn(II) ions are presented and the study includes results from thermogravimetric analysis (TG), scanning electron microscopy, X-ray diffraction, and leaching performance. Zn(II) ions delay the hydration reaction of Portland cement due to the formation of mainly CaZn2(OH)6 2H2O , as well as Zn5(CO3)2(OH)6, Zn(OH)2, and ZnCO3 in minor proportion. Correlations between total mass loss in TG analysis and leached Zn(II) ions in long-term curing pastes have been obtained. This result is important because in a preliminary approach from a TG on an early-aged cement paste containing Zn(II), it could be possible to perform an estimation of the amount of Zn(II) ions that could be leached, thus avoiding costly and time-consuming tests.Mellado Romero, AM.; Borrachero Rosado, MV.; Soriano Martinez, L.; Paya Bernabeu, JJ.; Monzó Balbuena, JM. (2013). Inmobilization of Zn(II) in Portland cement pastes. Determination of microstructure and leaching performance. Journal of Thermal Analysis and Calorimetry. 112(3):1377-1389. doi:10.1007/s10973-012-2705-8S137713891123Mojumdar SC, Sain M, Prasad RC, Sun L, Venart JES. Selected thermoanalytical methods and their applications from medicine to construction, Part I. J Therm Anal Calorim. 2007;90:653–62.Perraki M, Perraki T, Kolovos K, Tsivilis S, Kakali G. Secondary raw materials in cement industry. Evaluation of their effect on the sintering and hydration processes by thermal analysis. 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J Therm Anal Calorim. 2001;64:1011–6.Melchert MBM, Viana MM, Lemos MS, Dweck J, Buchler PM. Simultaneous solidification of two catalyst wastes and their effect on the early stages of cement hydration. J Therm Anal Calorim. 2011;105:625–33.Vessalas K, Thomas PS, Ray AS, Guerbois JP, Joyce P, Haggman J. Pozzolanic reactivity of the supplementary cementitious material pitchstone fines by thermogravimetric analysis. J Therm Anal Calorim. 2009;97:71–6.Tommaseo CE, Kersten M. Aqueous solubility diagrams for cementitious waste stabilization systems. 3. Mechanism of zinc immobilization by calcium silicate hydrate. Environ Sci Technol. 2002;36:2919–25.Peyronnard O, et al. Study of mineralogy and leaching behavior of stabilized/solidified sludge using differential acid neutralization analysis. Cem Conc Res. 2009. doi: 10.1016/j.cemconres.2009.03.016 .Moulin I, et al. Lead, zinc and chromium (III) and (VI) speciation in hydrated cement phases. 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Improving quality in nanoparticle-induced cytotoxicity testing by a tiered inter-laboratory comparison study

The quality and relevance of nanosafety studies constitute major challenges to ensure their key role as a supporting tool in sustainable innovation, and subsequent competitive economic advantage. However, the number of apparently contradictory and inconclusive research results has increased in the past few years, indicating the need to introduce harmonized protocols and good practices in the nanosafety research community. Therefore, we aimed to evaluate if best-practice training and inter-laboratory comparison (ILC) of performance of the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay for the cytotoxicity assessment of nanomaterials among 15 European laboratories can improve quality in nanosafety testing. We used two well-described model nanoparticles, 40-nm carboxylated polystyrene (PS-COOH) and 50-nm amino-modified polystyrene (PS-NH2). We followed a tiered approach using well-developed standard operating procedures (SOPs) and sharing the same cells, serum and nanoparticles. We started with determination of the cell growth rate (tier 1), followed by a method transfer phase, in which all laboratories performed the first ILC on the MTS assay (tier 2). Based on the outcome of tier 2 and a survey of laboratory practices, specific training was organized, and the MTS assay SOP was refined. This led to largely improved intra- and inter-laboratory reproducibility in tier 3. In addition, we confirmed that PS-COOH and PS-NH2 are suitable negative and positive control nanoparticles, respectively, to evaluate impact of nanomaterials on cell viability using the MTS assay. Overall, we have demonstrated that the tiered process followed here, with the use of SOPs and representative control nanomaterials, is necessary and makes it possible to achieve good inter-laboratory reproducibility, and therefore high-quality nanotoxicological data.Web of Science108art. no. 143

Consensus Paper: Radiological Biomarkers of Cerebellar Diseases

Hereditary and sporadic cerebellar ataxias represent a vast and still growing group of diseases whose diagnosis and differentiation cannot only rely on clinical evaluation. Brain imaging including magnetic resonance (MR) and nuclear medicine techniques allows for characterization of structural and functional abnormalities underlying symptomatic ataxias. These methods thus constitute a potential source of radiological biomarkers, which could be used to identify these diseases and differentiate subgroups of them, and to assess their severity and their evolution. Such biomarkers mainly comprise qualitative and quantitative data obtained from MR including proton spectroscopy, diffusion imaging, tractography, voxel-based morphometry, functional imaging during task execution or in a resting state, and from SPETC and PET with several radiotracers. In the current article, we aim to illustrate briefly some applications of these neuroimaging tools to evaluation of cerebellar disorders such as inherited cerebellar ataxia, fetal developmental malformations, and immune-mediated cerebellar diseases and of neurodegenerative or early-developing diseases, such as dementia and autism in which cerebellar involvement is an emerging feature. Although these radiological biomarkers appear promising and helpful to better understand ataxia-related anatomical and physiological impairments, to date, very few of them have turned out to be specific for a given ataxia with atrophy of the cerebellar system being the main and the most usual alteration being observed. Consequently, much remains to be done to establish sensitivity, specificity, and reproducibility of available MR and nuclear medicine features as diagnostic, progression and surrogate biomarkers in clinical routine

Cementitious materials with controlled volume changes for repairing and sealing works

Sporządzono spoiwa bezskurczowe i ekspansywne złożone z cementów portlandzkich o różnym składzie oraz z tak zwanego czynnika ekspansywnego stanowiącego mieszankę cementu glinowego oraz specjalnego spieku siarczanowo-wapniowego. Określono zmiany objętości stwardniałych zaczynów, jak również dynamikę narastania wytrzymałości i czas wiązania. Ustalono doświadczalnie proporcje składników mieszanek ekspansywnych oraz receptury spoiw. Dokonano prób wyjaśnienia zmian objętości w funkcji zawartości poszczególnych składników - przeprowadzono badania składu fazowego hydratyzujących materiałów oraz obserwacje mikroskopowe.The shrinkage-less and expansive binders were produced by mixing of different portland cements with an expansive agent composed of calcium aluminate cement and special sulfate-lime sinter. The volume changes, strength development and setting of binders were characterized. In the experiments the proportions of expansive mixtures and cementitious materials were stated. The investigations with aim to find the relationship between the volume changes and composition of initial mixtures were also carried out - the phase composition studies and microscopic observations were done