X-ray computed tomography investigation of structures in Opalinus Clay fromlarge-scale to small-scale after mechanical testing

In the past years X-ray computed tomography (CT) has became more and more common for geoscientific applications and is used from the µm-scale (e.g. for investigations of microfossils or pore-scale structures) up to the dm-scale (full drill cores or soil columns). In this paper we present results from CT imaging and mineralogical investigations of an Opalinus Clay core on different scales and different regions of interest, emphasizing especially the 3-D evaluation and distribution of cracks and their impact on mechanical testing of such material. Enhanced knowledge of the testing behaviour of the Opalinus Clay is of great interest, especially since this material is considered for a long-term radioactive waste disposal and storage facility in Switzerland. Hence, results are compared regarding the mineral (i.e. phase) contrast resolution, the spatial resolution, and the overall scanning speed. With this extensive interdisciplinary scale-down approach it has been possible to characterize the general fracture propagation in comparison to mineralogical and textural features of the Opalinus Clay. Additionally, and as far as we know, a so-called mylonitic zone, located at an intersect of two main fractures, has been observed for the first time for an experimentally deformed Opalinus sample. The multi-scale results are in good accordance to data from naturally deformed Opalinus Clay samples, which enables us to perform systematical research under controlled laboratory conditions. Accompanying 3-D imaging greatly enhances the capability of data interpretation and assessment of such a material

Oxidized and reduced kaolin fan deposits: Their sedimentological-mineralogical facies and physical-chemical regime (North-Bavarian Kaolin Mining District, Germany)

The kaolin-fan deposits under consideration are sedimentary in origin and they bridge the gap between residual kaolin deposits proximal to the fan apex in crystalline basement rocks and syn(dia)genetic sandstone-hosted kaolin deposits on the fan apron. The “kaolin ore beds” on the other hand, developed in an arenaceous braided-river drainage system (bed load >>> suspended load deposits), reworking into secondary kaolin deposits that took place either intraformationally during the evolution of the kaolin fan deposits or epigenetically after unroofing of the kaolin deposits in high-sinuosity drainage systems passing, locally, into ephemeral lakes and mud flats (suspended load > bed load deposits). The reference type for kaolin fan deposits has been studied in terrigeneous sediments which are largely mined at Hirschau–Schnaittenbach, along the Western edge of the Bohemian Massif, SE Germany. The fan deposits formed under alternating wet and dry subtropical climatic conditions during the early Triassic. Different intensities of uplift in the hinterland and the frequency of tectonic quiescence to tectonic pulse had a strong impact on the paleogradient, facies and hydrography of the kaolin fan deposits, resulting in the build-up of oxidized kaolin fans (OKF) and reduced kaolin fans (RKF). The OKF provide favorable conditions for the accumulation and preservation of kaolin deposits of economic potential, due to a low paleogradient and a continuous rate of uplift. The opposite is the case in the RKF that formed more proximal to the initial residual kaolin deposits and, more basinward, grade into sandstone-hosted (non)-sulfidic faciesbound Pb deposits that were targeted upon during exploration campaigns in the study area. The mineral association of the kaolin fan deposits has been categorized as follows: the allochthonous heavy minerals are zircon, tourmaline, apatite, monazite, xenotime, rutile, garnet, titaniferous magnetite, and ilmenite. They do not significantly vary between OKF and RKF. The autochthonous heavy minerals show strong contrasts in their heavy mineral suites. The RKF are enriched in sulfides and arsenides, which can be deleterious for the kaolin raw material and exclude its use for special final products (anatase, hematite, galena, sphalerite, marcasite, pyrite, bravoite (Ni pyrite), “limonite”, goethite, Ag–Cu–Ni–As sulfides, and barite). The OKF are rather poor in accessory minerals and contain anatase, hematite, and APS minerals. The latter are geo-acidometers (marker minerals for low pH) and considered as an ore guide to high-potential target areas for kaolin. The allochthonous light minerals quartz and K feldspar are common to both fan types and were only in parts affected by kaolinization, whereas plagioclase has been decomposed to completeness. Autochthonous light minerals quartz, chalcedony (carnelian), and calcite are exclusive to the RKF, where silcretes and calcretes evolved in those stratigraphic units which in the OKF only brought about Ca, Fe and Ti anomalies. The OKF have a significant edge over the RKF in terms of kaolin quality and kaolin exploitation (providing less mechanical wear on LHD [load–haul–dump machinery] machinery). Allochthonous phyllosilicates have a more widespread occurrence in the RKF with muscovite, biotite and chlorite most common in the lowermost kaolin beds. By quality there is not much difference among the autochthonous phyllosilicates of the OKF and RKF. Kaolinite-group minerals, illite, smectite, and an illite–smectite mixed-layer are present in both types, but kaolinite-group minerals prevail in the OKF, with a downward-increasing trend of dickite. By contrast the amount of smectite and smectite–illite mixed layers increases at the expense of kaolinite upward in the stratigraphy. The evolution of the kaolin fan deposits can be subdivided into six stages. Each stage is representative of a peculiar process which translates into concentration, preservation and destruction of kaolin: stage 1 weathering and the formation of a kaolin regolith (constructive), stage 2 transport, deposition synsedimentary to early-diagenetic kaolinization (constructive + preserving), stage 3 synsedimentary to early-diagenetic smectitization of kaolin (faciesbound Pb mineralization only in the RKF) (preserving + destructive), stage 4 late-diagenetic kaolinization and formation of dickite (preserving + constructive) (not in RKF), stage 5 epigenetic unconformity-related Cu–Ag–Ni–As–Ba mineralization (vaguely expressed in the OKF) (preserving), and stage 6 unroofing, erosion and redeposition of kaolin (only in the OKF) (destructive). During the study a PIMA device has proven in this type of kaolin deposit to be an efficacious tool for capturing digital data in the field of exploitation and exploration of industrial minerals for the identification and quantification of clay minerals (quality control)

Effectivity of a natural silica dust (AL06) compared to other natural and synthetic amorphous silica dusts against the granary weevil Sitophilus granarius (L.)

Sand, Lehm und Aschen zur Bekämpfung von Vorrats- und Hygieneschädlingen werden seit Jahrhunderten eingesetzt. Der zunehmende Bedarf an umweltschonenden alternativen Schädlingsbekämpfungsmitteln führte zu einer Renaissance des Einsatzes inerter Stäube, insbesondere von amorphen Diatomeenerden. Bei diesen Stäuben handelt es sich um fossile Ablagerungen der Silikatskelette von Kieselalgen (Diatomeen). Der insektizide Wirkmechanismus von Diatomeenerden (DE) besteht hauptsächlich in der Physiosorption von Cuticulalipiden und damit einhergehender Zerstörung der vor Austrocknung schützenden Wachsschicht der Cuticula (Mewis & Ulrichs, 2001a). Bei höherer relativer Luftfeuchte kommt es jedoch zu einer Sättigung der DE mit Wasser und dadurch zu einer Herabsetzung der Lipidaufnahmefähigkeit, welche die Wirksamkeit von DE bestimmt. Um DE auch bei höheren relativen Luftfeuchten einsetzen zu können, werden sie nachträglich hydrophobisiert (Faulde & al., 2006) bzw. werden direkt hydrophobe, synthetische Kieselsäuren eingesetztoder DE in Kombination mit anderen natürlichen Insektiziden verwendet (Ulrichs & Mewis, 2000; Akbar & al., 2004). Eine zusätzliche Hydrophobisierung von DE ist jedoch mit zusätzlichen Kosten verbunden. Des Weiteren sind synthetische Kieselsäuren aufgrund der geringen Partikelgrößen und der schlechten elektrostatischen Aufladbarkeit alleine schwer applizierbar. In Kooperation mit der Bundesanstalt für Geowissenschaften und Rohstoffe wurde deshalb an der Humboldt-Universität zu Berlin nach alternativen natürlichen Substanzen gesucht, die ähnliche physiko-chemische Eigenschaften aufweisen wie Diatomeenerden. Gefunden wurde ein natürlich vorkommendes Schichtsilikat mit großer Oberfläche, welches in den folgenden Versuchen mit AL06 bezeichnet wurde. In den durchgeführten Versuchen wurden insektizide Eigenschaften von AL06 im Vergleich zu weiteren natürlichen und synthetischen Silikaten untersucht.Common natural silica based insecticides such as diatomaceous earth (DE) are only effective under low relative humidities (r.h.). At r.h. above 60 % only surface modified, hydophobe DE’s and hydrophobe synthetic silica products can be used against insect pests. Chemical modification of DE is expensive while synthetic products are often difficult to apply because they cannot easily be charged for electrostatic application and have very small particle sizes. The present study compares the insecticidal effect of new naturally occurring silica (formulation name: AL06) with unmodified DE and synthetic silica products. In experiments with the granary weevil Sitophilus granarius (L.) all materials showed an insecticidal effect at 20 °C temperature and r.h. of 65 %. The natural DE product FossilShield FS100® showed the lowest degree of efficacy followed by AL06 whereby the hydrophobic materials Advasan® and PA910® showed the best activity. Already after 6 days in forced contact experiments with a dosage of 0.5 g/m² all materials resulted in 100 % mortality but differed in potential at lower rates. In contrast when substances were mixed with wheat at a dosage of 2 g/kg 100 % mortality occurred only with Advasan®. Here the mortality rate was reduced because insects can metabolize water from food sources. AL06 seems to be an alternative silica product for pest control strategies at higher r.h. The degree of efficacy of AL06 can be increased by modification of particle size and surface modifications (e.g. hydrophobe surfaces). Further studies with different AL06 formulations are currently ongoing

Porosity and permeability determination of organic-rich Posidonia shales based on 3-D analyses by FIB-SEM microscopy

The goal of this study is to better understand the porosity and permeability in shales to improve modelling fluid and gas flow related to shale diagenesis. Two samples (WIC and HAD) were investigated, both mid-Jurassic organic-rich Posidonia shales from Hils area, central Germany of different maturity (WIC R0 0.53 % and HAD R0 1.45 %). The method for image collection was focused ion beam (FIB) microscopy coupled with scanning electron microscopy (SEM). For image and data analysis Avizo and GeoDict was used. Porosity was calculated from segmented 3-D FIB based images and permeability was simulated by a Navier Stokes–Brinkman solver in the segmented images. Results show that the quantity and distribution of pore clusters and pores (≥  40 nm) are similar. The largest pores are located within carbonates and clay minerals, whereas the smallest pores are within the matured organic matter. Orientation of the pores calculated as pore paths showed minor directional differences between the samples. Both samples have no continuous connectivity of pore clusters along the axes in the x, y, and z direction on the scale of 10 to 20 of micrometer, but do show connectivity on the micrometer scale. The volume of organic matter in the studied volume is representative of the total organic carbon (TOC) in the samples. Organic matter does show axis connectivity in the x, y, and z directions. With increasing maturity the porosity in organic matter increases from close to 0 to more than 5 %. These pores are small and in the large organic particles have little connection to the mineral matrix. Continuous pore size distributions are compared with mercury intrusion porosimetry (MIP) data. Differences between both methods are caused by resolution limits of the FIB-SEM and by the development of small pores during the maturation of the organic matter. Calculations show no permeability when only considering visible pores due to the lack of axis connectivity. Adding the organic matter with a background permeability of 1 × 10−21 m2 to the calculations, the total permeability increased by up to 1 order of magnitude for the low mature and decreases slightly for the overmature sample from the gas window. Anisotropy of permeability was observed. Permeability coefficients increase by 1 order of magnitude if simulations are performed parallel to the bedding. Our results compare well with experimental data from the literature suggesting that upscaling may be possible in the future as soon as maturity dependent organic matter permeability coefficients can be determined

Применение дисперсионного анализа для исследования свойств промышленных наночастиц никеля

В работе были разработаны методики дисперсионного анализа нанопорошков в водных суспензиях разной концентрации для определения влияния абиотических факторов на агрегативную устойчивость наночастиц.The methods of dispersion analysis of nanopowders in aqueous suspensions of different concentrations were developed to determine the effect of abiotic factors on the aggregate stability of nanoparticles

Comprehensive examination of dehydroxylation of kaolinite, disordered kaolinite, and dickite: Experimental studies and density functional theory

Kaolins and clays are important rawmaterials for production of supplementary cementitious materials and geopolymer precursors through thermal activation by calcination beyond dehydroxylation (DHX). Both types of clay contain different polytypes and disordered structures of kaolinite but little is known about the impact of the layer stacking of dioctahedral 1:1 layer silicates on optimum thermal activation conditions and following reactivity with alkaline solutions. The objective of the present study was to improve understanding of the impact of layer stacking in dioctahedral 1:1 layer silicates on the thermal activation by investigating the atomic structure after dehydroxylation. Heating experiments by simultaneous thermal analysis (STA) followed by characterization of the dehydroxylated materials by nuclear magnetic resonance spectroscopy (NMR) and scanning electron microscopy (SEM) together with first-principles calculations were performed. Density functional theory (DFT) was utilized for correlation of geometry-optimized structures to thermodynamic stability. The resulting volumes of unit cells were compared with data from dilatometry studies. The local structure changes were correlated with experimental results of increasing DHX temperature in the following order: disordered kaolinite, kaolinite, and dickite, whereupon dickite showed two dehydroxylation steps. Intermediate structures were found that were thermodynamically stable and partially dehydroxylated to a degree of DHX of 75% for kaolinite, 25% for disordered kaolinite, and 50% for dickite. These thermodynamically stable, partially dehydroxylated intermediates contained AlV while metakaolinite and metadickite contained only AlIV with a strongly distorted coordination shell. These results indicate strongly the necessity for characterization of the structure of dioctahedral 1:1 layer silicates in kaolins and clays as a key parameter to predict optimized calcination conditions and resulting reactivity

ChimpACT: A Longitudinal Dataset for Understanding Chimpanzee Behaviors

Understanding the behavior of non-human primates is crucial for improving animal welfare, modeling social behavior, and gaining insights into distinctively human and phylogenetically shared behaviors. However, the lack of datasets on non-human primate behavior hinders in-depth exploration of primate social interactions, posing challenges to research on our closest living relatives. To address these limitations, we present ChimpACT, a comprehensive dataset for quantifying the longitudinal behavior and social relations of chimpanzees within a social group. Spanning from 2015 to 2018, ChimpACT features videos of a group of over 20 chimpanzees residing at the Leipzig Zoo, Germany, with a particular focus on documenting the developmental trajectory of one young male, Azibo. ChimpACT is both comprehensive and challenging, consisting of 163 videos with a cumulative 160,500 frames, each richly annotated with detection, identification, pose estimation, and fine-grained spatiotemporal behavior labels. We benchmark representative methods of three tracks on ChimpACT: (i) tracking and identification, (ii) pose estimation, and (iii) spatiotemporal action detection of the chimpanzees. Our experiments reveal that ChimpACT offers ample opportunities for both devising new methods and adapting existing ones to solve fundamental computer vision tasks applied to chimpanzee groups, such as detection, pose estimation, and behavior analysis, ultimately deepening our comprehension of communication and sociality in non-human primates.Comment: NeurIPS 202

Chimpanzees behave prosocially in a group-specific manner

Funding: EJCvL was funded by a Postdoctoral Fellowship awarded by the Research Foundation Flanders (FWO) and an ERC-Synergy Grant (no. 609819) awarded to JC.Chimpanzees act cooperatively in the wild, but whether they afford benefits to others, and whether their tendency to act prosocially varies across communities, is unclear. Here, we show that chimpanzees from neighboring communities provide valuable resources to group members at personal cost, and that the magnitude of their prosocial behavior is group specific. Provided with a resource-donation experiment allowing free (partner) choice, we observed an increase in prosocial acts across the study period in most of the chimpanzees. When group members could profit (test condition), chimpanzees provided resources more frequently and for longer durations than when their acts produced inaccessible resources (control condition). Strikingly, chimpanzees’ prosocial behavior was group specific, with more socially tolerant groups acting more prosocially. We conclude that chimpanzees may purposely behave prosocially toward group members, and that the notion of group-specific sociality in nonhuman animals should crucially inform discussions on the evolution of prosocial behavior.Publisher PDFPeer reviewe

Porosity and distribution of water in perlite from the island of Milos, Greece

A perlite sample representative of an operating mine in Milos was investigated with respect to the type and spatial distribution of water. A set of different methods was used which finally provided a consistent view on the water at least in this perlite. Infrared spectroscopy showed the presence of different water species (molecular water and hydroxyl groups / strongly bound water). The presence of more than 0.5 mass% smectite, however, could be excluded considering the cation exchange capacity results. The dehydration measured by thermal analysis occurred over a wide range of temperatures hence confirming the infrared spectroscopical results. Both methods point to the existence of a continuous spectrum of water binding energies. The spatial distribution of water and/or pores was investigated using different methods (CT: computer tomography, FIB: scanning electron microscopy including focused ion beam technology, IRM: infrared microscopy). Computer tomography (CT) showed large macropores (20 – 100 μm) and additionally revealed a mottled microstructure of the silicate matrix with low density areas up to a few μm in diameter. Scanning electron microscopy (FIB) confirmed the presence of μm sized pores and IRM showed the filling of these pores with water. In summary, two types of pores were found. Airfilled 20 – 100 μm pores and μm-sized pores disseminated in the glass matrix containing at least some water. Porosity measurements indicate a total porosity of 26 Vol%, 11 Vol% corresponding to the μm-sized pores. It remains unsolved wether the water in the μm-sized pores entered after or throughout perlite formation. However, the pores are sealed and no indications of cracks were found which indicated a primary source of the water, i.e. water was probably entrapped by quenching of the lava. The water in these pores may be the main reason for the thermal expandability which results in the extraordinarily porous expanded perlite building materials