The reactivity of basal surfaces, steps and edges of muscovite was studied by imaging surface precipitates of PbCl2 using atomic force microscopy (AFM). We reacted PbCl2 solution with freshly cleaved muscovite surfaces and found that PbCl2 precipitates were formed on the basal surfaces, steps and edges. It was observed that PbCl2 precipitated preferentially along the steps compared to the basal surfaces and that PbCl2 precipitates at multiple-layer edges were needle-shaped and oriented in different directions. One of the muscovite samples we cleaved had muscovite fragments sitting on the freshly cleaved surfaces. These fragments resulted from previously formed cracks. Thus, we were able to compare the reactivity of the weathered surfaces with that of freshly cleaved surfaces. It was found that PbCl2 was not precipitated along the edges of previously cracked muscovite fragments. These results clearly demonstrated that the edges of freshly cleaved muscovite are the most reactive surface sites, whereas the edges of weathered muscovite are not as reactive. We believe that the surface reactivity of the edges of freshly cleaved muscovite is likely due to terminal or Al-OH1/2− groups on these crystalline surfaces, which favor adsorption of Pb2+ ions and the subsequent nucleation and precipitation reactions. We also investigated the effect of drying rate on the morphology of the surface precipitates. Fast drying resulted in a nearly complete covered surface with a leaflike morphology, whereas slow drying resulted in more isolated surface clusters.

The storage of CO2 in geological reservoirs requires an understanding of the impact of CO2 on clay-rich sealing cap-rocks to identify and explore critical parameters that modify petrophysical properties such as permeability and fracturing. The purpose of this study was to investigate the effect of heating, under different hydrated-CO2 partial pressures, on the chemical compositions and relative amounts of mineral phases in the Saint Martin de Bossenay (SMB, Paris Basin, France) cap-rock in order to identify possible mineral-phase transitions and to estimate reaction kinetics induced by the presence of excess dissolved CO2.

X-ray diffraction, transmission electron microscopy, and electron microprobe analyses were employed to study mineral alteration, with particular attention given to visualization and quantification of the mineral evolution of clay minerals. In all the altered mixtures investigated, the illitization of clays was combined with the formation of anhydrite. These changes were accompanied by a dolomitization and a slight increase in the quartz content. The CO2-rich samples crystallized Fe2+-and K+-enriched illites, whereas the CO2-free experiments precipitated Al3+-deprived and Mg2+-enriched illites. Advanced characterizations of cap-rock material allowed reaction paths, induced by the increase in dissolved CO2 in the porous media, to be determined precisely. The results place strong constraints on numerical models aimed at evaluating the safety of an SMB site.

Whereas physiological and behavioural responses to acute stressors are well documented, chronic stress remains difficult to assess in farm animals. The aim of the present paper is to investigate whether calves’ behavioural reactions to acute events are modified during chronic intermittent stress. Thirty-two calves housed in pairs were used. For half of the calves the partner and the pen were changed once a week for 14 weeks (regrouped calves) while the others remained unchanged (controls). Four behavioural tests were performed to assess calves’ reactivity to novel or sudden events, to predator cues and to restraint. In the water spray test, regrouped calves were startled more often. In the umbrella test, regrouped calves took a longer time to feed in front of the closed umbrella but no differences between the two treatments were observed on opening the umbrella. In the dog test, regrouped calves moved more and looked at the dog more often. In the restraint test, regrouped calves were more agitated. These differences disappeared when the tests were repeated. In conclusion, repeated changes in the social and physical environment of calves enhances their behavioural reactivity to novelty. This is likely to make them more adaptive to potential changes in their environment.

White-lipped (Tayassu pecari) and collared (Pecari tajacu) peccaries can be farmed as an alternative to subsistence hunting in Neotropical countries. The animals often show high reactivity to handling, usually involving capture with a net, which is a cause for concern because it poses risks to both animals’ and keepers’ welfare. We aimed to assess the temperament of both peccary species, evaluating animals’ reactions during handling, providing an emotional indicator and a new animal selection criterion for peccary farms. Three indicators were used to assess the temperament of 17 white-lipped and 19 collared peccaries: qualitative behaviour assessment (QBA, by using 12 behavioural adjectives); time to drive each animal through a corridor into a chute (TD, s); and flight speed (FS, m s−1). A Principal Components Analysis was performed for the QBA data to define a temperament index (TI). White-lipped peccaries showed TI scores associated with worse temperament traits than collared peccaries. White-lipped peccaries showed higher TD and FS means than collared peccaries. We found a correlation between TD and FS, but not between TD and TI, nor between FS and TI. The lack of correlation between all temperament indicators occurred, probably, because they measure different aspects of peccaries’ reactions toward humans and the farm environment during handling. A wide phenotypic variability was found among individuals within both species’ populations. The results provide an opportunity to address the role of temperament assessment, improving handling procedures and exploring the possibility of including temperament as a selection criterion in captive breeding programmes.

Logic Production System (LPS) is a logic-based framework for modelling reactive behaviour. Based on abductive logic programming, it combines reactive rules with logic programs, a database and a causal theory that specifies transitions between the states of the database. This paper proposes a systematic mapping of the Kernel of this framework (called KELPS) into an answer set program (ASP). For this purpose a new variant of KELPS with finite models, called n-distance KELPS, is introduced. A formal definition of the mapping from this n-distance KELPS to ASP is given and proven sound and complete. The Answer Set Programming paradigm allows to capture additional behaviours to the basic reactivity of KELPS, in particular proactive, pre-emptive and prospective behaviours. These are all discussed and illustrated with examples. Then a hybrid framework is proposed that integrates KELPS and ASP, allowing to combine the strengths of both paradigms.

Previous research on reactivity—defined as changing organizational behaviour to better conform to the criteria of measurement in response to being measured—has found significant variation in company responses toward sustainability metrics. We propose that reactivity is driven by dialogue, motivation, and capacity in a configurational way. Empirically, we use fuzzy set qualitative comparative analysis to analyze company responses to the sustainability index FTSE4Good. We find evidence of complementary and substitute effects between motivation and capacity. Based on these effects, we develop a typology of reactivity to sustainability metrics, which also theorizes the use of metrics as tools for performance feedback and the building of calculative capacity. We show that when reactivity is studied configurationally, we can identify previously underacknowledged types of responses. We discuss the theoretical and practical implications for studying and using sustainability metrics as governance tools for responsible behaviour.

Reactions in Ni/Al nanolaminates exhibit high combustion temperatures and wave speeds that are customizable through changes to nanostructure. Nanolaminates fabricated via vapor deposition exhibit columnar grains with average diameters on the order of the individual layer thickness; yet, their role on nanolaminate combustion has not been previously investigated. The current work uses molecular dynamics simulations to elucidate the effect of grain size on reaction rates and combustion temperatures in Ni/Al nanolaminates. Decreasing grain size is shown to increase reaction rates as well as increase peak temperatures consistent with the excess enthalpy of smaller grain sizes. Additionally, grain boundaries provide heterogenous nucleation sites for the diffusion-restricting B2–NiAl phase. Focusing on Ni diffusion into liquid Al, an effective diffusion coefficient is computed as a function of grain size, which may be used in thermodynamic models for this stage of the reaction.

Polyurea resins derived from tolyldiisocyante (TDI) and a reactive solvent-free nanofluid (NF-NH2) surface-decorated with propylamines can be tuned over three to five orders of magnitude in storage modulus (10 MPa to 10 GPa) and hardness modulus (6 kPa to 4 GPa) by varying weight fractions of components. The thermal properties of this NF-NH2 are similar to several other nanofluids reported using the same bulky anionic counterion that also imparts liquidity in the absence of any solvent. This tuning suggests applications ranging from opaque protective coatings to clearcoats to sealants to adhesives.

The photostability of two glycine molecules has been investigated using quantum mechanical methods i.e. at CASSCF/NEVPT2 level theory. It is found that the molecule in water shows vast photostability as a comparison to vacuum. The energies are calculated around HOMO and LUMO orbital. The NEVPT2 computed energies are reasonably matched with experimental results. The study shows that the molecule returns from higher electronically excited states to ground state through CI and AC crossings and these crossings provide a minimum energy path along derivative coupling and gradient differences vector.

Many agrowastes are being used for energy production by combustion in power plants. This process generates huge amounts of ash, which has a potential pozzolanic activity for blending with Portland cement or hydrated lime. In this paper, the ash obtained from elephant grass (Pennisetum purpureum Schum var. purple) leaves (EGLs) was studied, including the silicon content and its distribution, the presence of other compounds, and in addition, the presence of silica bodies (phytoliths). Combustion temperatures of 450 and 650°C produced an unaltered inorganic skeleton (spodogram), whereas at 850°C, there is a sintering process because of high potassium content in the ash. Phytoliths and different types of hairs were identified, and they contained high percentages of silica. Magnesium (mainly as periclase) was distributed in the most porous parts in the interior of the leaves. The silica can react with calcium hydroxide (pozzolanic reaction) forming calcium silicate hydrates (observed by field-emission scanning electron microscopy and thermogravimetric analysis). Fixed lime percentages at 28 curing days (63%) indicated the high reactivity of EGL ashes in calcium hydroxide pastes due to the pozzolanic reaction. This study demonstrates the possibility of the reuse of ashes from EGLs for the production of environmental-friendly cements.

Green rusts, GRs, can act as both sorbents and reductants towards selected pollutants. Organo-GRs are expected to combine these properties with a high affinity for hydrophobic substances. A novel organo-GR, GRLAS, was synthesized by incorporating a mixture of linear alkylbenzenesulphonates (LAS) into the interlayer space of synthetic sulphate green rust, GRSO4 . Mössbauer analysis of GRLAS indicates that the structure of the organo-GR is very similar to that of the initial GRSO4 with regard to the FeII/FeIII ratio and local coordination of Fe atoms. X-ray diffraction demonstrates that the GRLAS formed was well ordered, although a mixture of surfactant was used for intercalation. The basal spacings of the GRLAS and the kinetics of the ion-exchange process were dependent on the initial surfactant loading; basal spacings of ~2.85 nm were obtained at LAS solution concentrations >10 mM. The ratio LASadsorbed/SO42–desorbed significantly exceeded the stoichiometric ratio of 2 during the initial part of the ion-exchange process (t = 5 h). However, this ratio was reached progressively with time. GRSO4 preferentially sorbed LAS homologues with long alkyl chains over short ones. Carbon tetrachloride was successfully adsorbed into GRLAS. The adsorption isotherm was linear with a distribution coefficient, Kd, of 505±19 litre kg–1.

A novel approach based on the preceramic paper method was used for the fabrication of Ti3SiC2-based material. Elemental powders of Ti, TiC, Si, C, and organic additives were used as starting materials. The Rapid Köthen process was used to fabricate the preceramic papers. The high-loaded green body of preceramic papers was heat-treated up to varying temperatures of 1300, 1400, 1500, and 1600 °C for 1 h in an Ar atmosphere. By using an excess amount of Si powder in the basic composition, the amount of Ti3SiC2 in the sintered specimen could be increased while the amount of TiC could be reduced. X-ray analysis showed that the paper-derived sample with the basic powder composition 3Ti/3TiC/3Si/C was a single phase within the resolution limit of the instrument used. The high purity of Ti3SiC2 can be explained by the partial formation of amorphous C which could not be detected by X-ray diffraction. Scanning electron microscopy analysis of fracture surfaces showed the characteristic lamellar structure of the paper-derived MAX phase.

In this study, Ni based ferrite nanomaterials were synthesized using sol-gel method for solar thermochemical splitting of CO2 using a thermogravimetric analyzer. To synthesize the ferrite materials, the corresponding metal precursors were dissolved in ethanol (with required molar ratios). After achieving the dissolution, propylene oxide (PO) was added to achieve the gel formation. Freshly synthesized gels were aged, dried, and calcined by heating up to 600°C in air. Powder x-ray diffractometer (XRD), BET surface area, as well as scanning (SEM) and transmission (TEM) electron microscopy characterized the calcined powders. The sol-gel derived ferrites were further tested towards their thermal reduction and CO2 splitting ability using a high temperature thermogravimetric analyzer (TGA).

This study investigates the use of ‘simple’ glasses, comprising six components, to represent the structure of complex LAW glasses proposed for Immobilized Low Activity Wastes from the Hanford site in the USA. The 18 elements present in ILAW glasses LAW A44, ORP LB2, and LAW A23 were represented by Al2O3, B2O3, CaO, Na2O, SiO2, and ZrO2 according to their coordination chemistry and their roles as network formers and modifiers. The dissolution behavior of each ‘simple’ glass was compared to its corresponding candidate “complex” LAW glass through PCT-B tests. Significant differences were observed; the durability of complex glasses was concluded to be LAW A44 > ORP LB2 ≥ LAW A23 whereas in their simplified versions the order was LAW A44 > LAW A23 > ORP LB2. These results are discussed in relation to compositional differences and highlight the importance of minor glass components in controlling glass durability. The implications of these results for the use of simplified glass compositions are discussed.

Recent studies on graphene hydrogenation processes showed that hydrogenation occurs via island growing domains, however how the substrate can affect the hydrogenation dynamics and/or pattern formation has not been yet properly investigated. In this work we have addressed these issues through fully atomistic reactive molecular dynamics simulations. We investigated the structural and dynamical aspects of the hydrogenation of graphene membranes (one-side hydrogenation, the so called graphone structure) on different substrates (graphene, few-layers graphene, graphite and platinum). Our results also show that the observed hydrogenation rates are very sensitive to the substrate type. For all investigated cases, the largest fraction of hydrogenated carbon atoms was for platinum substrates. Our results also show that a significant number of randomly distributed H clusters are formed during the early stages of the hydrogenation process, regardless of the type of substrate. These results suggest that, similarly to graphane formation, large perfect graphone-like domains are unlikely to be formed. These findings are especially important since experiments have showed that cluster formation influences the electronic transport properties in hydrogenated graphene.

The behavior of nanostructures under high strain-rate conditions has been object of interest in recent years. For instance, recent experimental investigations showed that at high velocity impacts carbon nanotubes can unzip resulting into graphene nanoribbons. Carbon nanoscrolls (CNS) are among the structures whose high impact behavior has not yet been investigated. CNS are graphene membranes rolled up into papyrus-like structures. Their unique open-ended topology leads to properties not found in close-ended structures, such as nanotubes. Here we report a fully atomistic reactive molecular dynamics study on the behavior of CNS colliding at high velocities against solid targets. Our results show that the velocity and scroll axis orientation are key parameters to determine the resulting formed nanostructures after impact. The relative orientation of the scroll open ends and the substrate is also very important. We observed that for appropriate velocities and orientations, the nanoscrolls can experience large structural deformations and large-scale fractures. We have also observed unscrolling (scrolls going back to planar or quasi-planar graphene membranes), unzip resulting into nanoribbons, and significant reconstructions from breaking and/or formation of new chemical bonds. Another interesting result was that if the CNS impact the substrate with their open ends, for certain velocities, fused scroll walls were observed.