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Abstract Animal experimentation has been fundamental in biological and biomedical research. To guarantee the maximum quality, efficacy and/or safety of products intended for the use in humans in vivo testing is necessary; however, for over 60 years, alternative methods have been developed in response to the necessity to reduce the number of animals used in experimentation, to guarantee their welfare; resorting to animal models only when strictly necessary. The three Rs (Replacement, Reduction, and Refinement), seek to ensure the rational and respectful use of laboratory animals and maintain an adequate projection in terms of bioethical considerations. This article describes different approaches to apply 3Rs in preclinical experimentation for either research or regulatory purposes.

One of the most challenging issues in Mediterranean ecosystems to date has been to understand the emergence of discontinuous changes or catastrophic shifts. In the era of the 2030 Sustainable Development Goals, which encompass ideas around Land Degradation Neutrality, advancing this understanding has become even more critical and urgent. The aim of this paper is to synthesize insights into the drivers, processes and management of catastrophic shifts to highlight ways forward for the management of Mediterranean ecosystems. We use a multidisciplinary approach that extends beyond the typical single site, single scale, single approach studies in the current literature. We link applied and theoretical ecology at multiple scales with analyses and modeling of human–environment–climate relations and stakeholder engagement in six field sites in Mediterranean ecosystems to address three key questions: i)How do major degradation drivers affect ecosystem functioning and services in Mediterranean ecosystems?ii)What processes happen in the soil and vegetation during a catastrophic shift?iii)How can management of vulnerable ecosystems be optimized using these findings?Drawing together the findings from the use of different approaches allows us to address the whole pipeline of changes from drivers through to action. We highlight ways to assess ecosystem vulnerability that can help to prevent ecosystem shifts to undesirable states; identify cost-effective management measures that align with the vision and plans of land users; and evaluate the timing of these measures to enable optimization of their application before thresholds are reached. Such a multidisciplinary approach enables improved identification of early warning signals for discontinuous changes informing more timely and cost-effective management, allowing anticipation of, adaptation to, or even prevention of, undesirable catastrophic ecosystem shifts.

Global warming is expected to increase the rate of CH4 emission from acidic peatlands leading to an increased interest on its mechanisms of formation. The main routes are through the reduction of CO2 by molecular hydrogen and through the cleavage of acetate. A predominance of the former, a reaction which also competes with homoacetogenesis to form acetate, may enrich the media in acetate, which could potentially be incorporated in the peat molecular markers. Acetates of triterpenoid biomarkers have been identified in peats and lake sediments and related to the input of higher plants. Nevertheless, the acetyl derivatives are found in very low amounts in fresh plants and in much lower amount than other derivatives with alcohol or ketone functional groups. The dichloromethane/methanol extracts of Asturian peat bog profiles (North Spain) were analyzed using gas chromatography/mass spectrometry (GC/MS) and compound-specific-isotope-analysis (CSIA). They show abundance of acetates of compounds with oleanane, ursane, and lupane skeletons derived from higher plants and with hopane skeleton, which can be considered a characteristic of these peats. Two families of 3-oxyhopenyl acetates with -17(21)- and -22(29)- configurations were detected in the upper part of the peat profiles, having a δ13C isotopic composition enriched by 4‱ compared with that of higher plant triterpenoids, and similar to that of microorganism-derived regular hopanoids. Both the acetate and ketone derivatives with the oxygenated functionality at C-3 were generally present in a given extract and tended to accumulate at certain depth in the profiles and in specific levels. The widespread occurrence of acetyl-derivatives, their higher concentration in the deeper layers of the peat, the fact that the acetates correspond to different compound families of diverse source and the very low amount of acetates identified in Ericaceae-contributing to the peat compared to the alcohols suggest that they were formed in the peat under particularly favorable environmental conditions. We postulate that these conditions could have been the existence of a medium enriched in acetic acid produced by the dominance of hydrogenotrophic methanogenesis and/or homoacetogenesis over acetoclastic methanogenesis. This phenomenon that has been preferentially described in Sphagnum bogs at high latitudes, and in the deeper layers of peat, appears to be also present in the temperate peats of the Asturian coast.

The Sahel (a semi-arid fringe south of the Sahara) experienced a long and prolonged drought from the 1970s to the mid-1990s, with a few extremely severe episodes that strongly affected ecosystems and societies. Long-term observations showed that surface runoff increased during this period, despite the rainfall deficit. This paradox stems from the soil degradation that was induced by various factors, either directly linked to the drought (impact on vegetation cover), or, in places, to human practices (land clearing and cropping). Surface runoff is still increasing throughout the region, suggesting that Sahelian ecohydrosystems may have shifted to a new hydrological regime. In order to explore this issue, we have developed a simple system dynamics model incorporating vegetation–hydrology interactions and representing in a lumped way the first order processes occurring at the hillslope scale and the annual timestep. Long term observations on a pilot site in northern Mali were used to constrain the model and define an ensemble of plausible simulations. The model successfully reproduced the vegetation collapse and the runoff increase observed over the last 60 years. Our results confirmed that the system presents two alternative states and that during the drought it shifted from a high-vegetation/low-runoff regime to the alternative low-vegetation/high-runoff one, where it has remained trapped until now. We showed that the mean annual rainfall deficit was sufficient to explain the shift. According to the model, vegetation recovery and runoff reduction are possible in this system, but the conditions in which they could occur remain uncertain as the model was only constrained by observations over the collapse trajectory. The study shows that the system is also sensitive to the interannual and decadal variability of rainfall, and that larger variability leads to higher runoff. Both mean rainfall and rainfall variability may increase in central Sahel under climate change, leading to antagonist effects on the system, which makes its resilience uncertain.

The Rietveld-internal standard method for Bragg-Brentano reflection geometry (θ/2θ) X-ray diffraction (XRD) patterns is implemented to determine the amorphous phase content. The effect of some minor phases on quantitative accuracy is assessed. The numerical simulation analysis of errors and the related corrections are discussed. The results reveal that high purity of crystalline phases in the standard must be strictly ensured. The minor amorphous or non-quantified crystalline phases exert significant effect on the quantitative accuracy, even with less than 2 wt% if ignored. The error levels are evaluated by numerical simulation analysis and the corresponding error-accepted zone is suggested. To eliminate such error, a corrected equation is proposed. When the adding standard happens to be present in sample, it should be also carefully dealt with even in low amounts. Based on that ignorance, the absolute and relative error equations (ΔAE, ΔRE) are derived, as proposed. The conditions for high quantitative accuracy of original equation is strictly satisfied with a lower amount of standard phase present in sample, less than 2 wt%, and a higher dosage of internal standard, larger than 20 wt%. The corrected equation to eliminate such quantitative error is suggested.

The analysis of atomic ordering in a nanocrystalline phase with small particle sizes, below 5 nm, is intrinsically complicated because of the lack of long-range order. Furthermore, the presence of additional crystalline phase(s) may exacerbate the problem, as is the case in cement pastes. Here, we use the synchrotron pair distribution function (PDF) chiefly to characterize the local atomic order of the nanocrystalline phases, gels, in cement pastes. We have used a multi r-range analysis approach, where the ~4–7 nm r-range allows determining the crystalline phase contents; the ~1–2.5 nm r-range is used to characterize the atomic ordering in the nanocrystalline component; and the ~0.2–1.0 nm r-range gives insights about additional amorphous components. Specifically, we have prepared four alite pastes with variable water contents, and the analyses showed that a defective tobermorite, Ca11Si9O28(OH)2.8.5H2O, gave the best fit. Furthermore, the PDF analyses suggest that the calcium silicate hydrate gel is composed of this tobermorite and amorphous calcium hydroxide. Finally, this approach has been used to study alternative cements. The hydration of monocalcium aluminate and ye’elimite pastes yield aluminum hydroxide gels. PDF analyses show that these gels are constituted of nanocrystalline gibbsite, and the particle size can be as small as 2.5 nm.

Portland cements (PCs) and cement blends are multiphase materials of different fineness, and quantitatively analysing their hydration pathways is very challenging. The dissolution (hydration) of the initial crystalline and amorphous phases must be determined, as well as the formation of labile (such as ettringite), reactive (such as portlandite) and amorphous (such as calcium silicate hydrate gel) components. The microstructural changes with hydration time must also be mapped out. To address this robustly and accurately, an innovative approach is being developed based on in situ measurements of pastes without any sample conditioning. Data are sequentially acquired by Mo Kα1 laboratory X‐ray powder diffraction (LXRPD) and microtomography (µCT), where the same volume is scanned with time to reduce variability. Wide capillaries (2 mm in diameter) are key to avoid artefacts, e.g. self‐desiccation, and to have excellent particle averaging. This methodology is tested in three cement paste samples: (i) a commercial PC 52.5 R, (ii) a blend of 80 wt% of this PC and 20 wt% quartz, to simulate an addition of supplementary cementitious materials, and (iii) a blend of 80 wt% PC and 20 wt% limestone, to simulate a limestone Portland cement. LXRPD data are acquired at 3 h and 1, 3, 7 and 28 days, and µCT data are collected at 12 h and 1, 3, 7 and 28 days. Later age data can also be easily acquired. In this methodology, the amounts of the crystalline phases are directly obtained from Rietveld analysis and the amorphous phase contents are obtained from mass‐balance calculations. From the µCT study, and within the attained spatial resolution, three components (porosity, hydrated products and unhydrated cement particles) are determined. The analyses quantitatively demonstrate the filler effect of quartz and limestone in the hydration of alite and the calcium aluminate phases. Further hydration details are discussed. [ABSTRACT FROM AUTHOR]

On the one hand, calcium sulfoaluminate (CSA) eco-cements release about 40% less carbon dioxide (CO2) than Portland cement during fabrication; on the other hand, phase change materials dispersed in a cementitious matrix can help to optimise the indoor temperature of buildings, reducing carbon dioxide emissions related to heating/air conditioning. However, this is only economically viable if it is used as a thin layer (a coating). In addition, the combination of both materials supposes a double environmental benefit. Consequently, the main objective of this work is the preparation of a suitable homogeneous and well-adhered bilayer sample, composed of CSA and CSA-MPCM. To achieve this, in the first step, the effect of pH, temperature and stirring was studied for microencapsulated phase change material (MPCM) aqueous suspensions (47.3 wt%); second, the MPCM (45 wt% with respect to dry cement) was dispersed in a CSA paste; then, in a third step, a homogeneous well-adhered coating of CSA-MPCM, with undamaged MPCM, was obtained on a CSA matrix. This was achieved through rheological measurements and checked by microscopy. Finally, the corresponding CSA and CSA-MPCM mortars were characterised through their mechanical properties (compression) (70 and 13 MPa at 7 days, respectively) and thermal conductivity (2.06 and 1.19 W/mK, respectively). [ABSTRACT FROM AUTHOR]