Todorokite is a common Mn oxide (with a tunnel structure) in the Earth surface environment, and can be obtained by hydrothermal treatment or refluxing process from precursor buserite with a layered structure. Several chemical reaction conditions for the phase transformation from Na-buserite to todorokite at atmospheric pressure were investigated, including temperature, pH, crystallinity of precursor Na-buserite, the amount of the interlayer Mg2+ of the Mg-buserite and clay minerals. The results showed that the conversion rate and crystallinity of todorokite decreased with falling temperature, and Mg-buserite could not be completely transformed to todorokite at lower temperatures (40°C). The poorly crystalline Na-buserite could be converted into todorokite more easily than highly crystalline Na-buserite. Todorokite can be prepared at pH 5–9, but the rate of conversion and crystallinity of todorokite did vary with pH in the order: neutral ≈ alkali > acidic. The conversion rate of todorokite decreased with decreasing interlayer Mg2+ content of the Mg-buserite. The presence of montmorillonite or goethite slowed the formation reaction of todorokite in the refluxing process, and the reaction time was prolonged when the amounts of those minerals were increased.

Soils developed on Pleistocene andesitic lava flows and fluvial detritus in the Atlantic coastal plain of Costa Rica display a clay mineral assemblage that includes 10 Å and 7 Å halloysite and lesser amounts of kaolinite and dioctahedral vermiculite. Other secondary minerals include gibbsite, goethite, hematite, maghemite, allophane and amorphous Al hydroxides. Active floodplain soils are dominated by 10 Å halloysite and contain less allophane, while soil clays from Pleistocene terraces consist of a mixture of 10 Å and 7 Å halloysite as well as less dioctahedral vermiculite, kaolinite, and amorphous Al hydroxides. Residual soils formed on Pleistocene lava flows are dominated by 7 Å halloysite with less abundant kaolinite, dioctahedral vermiculite, 10 Å halloysite and amorphous Al hydroxides. This sequence suggests transformations of 10 Å halloysite to 7 Å halloysite and allophane to amorphous Al hydroxides with time. The presence of 10 Å halloysite in Pleistocene terrace soils implies slow reaction rates or metastability.

Quantitative X-ray diffraction (QXRD) analysis indicates a decrease in the amount of plagioclase feldspar from 34 wt.% in the 1–2 year floodplain to 0–1.6% in terrace and residual soils. Plagioclase weathering is paralleled by the formation of dioctahedral clay, allophane and Al hydroxides. Analysis by QXRD also indicates that crystalline minerals comprise 70–95% of the soil fraction, implying 5–30% X-ray-amorphous material. These data are verified by selective extraction using ammonium oxalate, which indicates 8–30% amorphous material. Chemical analysis of the extractant by inductively coupled plasmaatomic emission spectrometry indicates that allophane (Al:Si ratios of 0.92–3.82) occurs in floodplain and some terrace soils while amorphous Al hydroxides appear to coexist with allophane in Pleistocene terrace and residual soils with Al:Si ratios of 6.53–8.53. Retention of Mg to a greater extent than Na, Ca and K suggests Mg incorporation into hydroxide sheets in dioctahedral vermiculite as well as substitution into hydroxides.

Das Papier bezieht sich auf die exegetische Auffassung, es beruhe die Argumentation von Gal 3,10 gerade auch auf einer unterdrückten praemissa minor („die Toravorschriften lassen sich nicht vollständig einhalten“), und es richtet sich gegen die These von P. C. Moore, nach welcher die in 2,16c aufgenommenen Worte aus Ps 143(142),2 genau diese Prämisse bieten sollen. Nicht zuletzt die Aufeinanderfolge der Partikeln γάρ, (ὅτι) δέ, ὅτι und δέ in Gal 3,10b, 11a, 11b und 12a lässt auf ein deutlich wahrscheinlicheres Szenario aufmerken: Paulus argumentiert in 3,10-12 mittels zweier Syllogismen, und er benutzt dabei letztlich durch biblische Formulierungen (aus: Deut 27,26; Hab 2,4; Lev 18,5) vorgegebene, abgesicherte Prämissen.

The capture and storage of carbon dioxide (CO2) have considerable potential for mitigating climate change. Adsorption is one of the most popular methods for the storage of CO2. The adsorption of CO2 molecules on the hydroxylated (001) surface of kaolinite was investigated using density-functional theory within the generalized gradient approximation and a supercell approach. The coverage dependence of the adsorption structures and energetics was studied systematically for a wide range of coverage, Θ [from 0.11 to 1.0 monolayers (ML)], and adsorption sites. The CO2 was adsorbed on the two-fold bridge-x (see the text for a definition) and the one-fold top-x sites in the bent, recumbent configuration, and on the three-fold hollow-z, two-fold bridge-z site, and the one-fold top-z sites in the vertical configuration. The surface-adsorbed binding site of CO2 was strongest at the bridge-x site and weakest at the top-z site. The adsorption energy increased with coverage, thus indicating the greater stability of surface adsorption and a tendency to form CO2 islands (clusters) with increasing coverage. The other properties of the CO2/kaolinite (001) system, including the different charge distribution, the lattice relaxation, and the electronic density of states, were also studied and are discussed in detail.

Calcined clays are used as a supplementary cementitious material (SCM) because, as hydrated aluminosilicates of the phyllosilicate group, they can be activated thermally, promoting dehydroxylation and structural disorder, i.e. making them reactive. The main effect of using calcined clay as an SCM is that CO2 emissions into the atmosphere are reduced by the reduction in the clinker/cement factor due to substitution of a proportion of clinker by calcined clay. Clays rich in kaolinite (1:1) group minerals offer most promise in terms of thermal activation. However, increased costs caused by demand for kaolinite from other industries means that type 2:1 calcined clays and mixtures of them have begun to be investigated as possible pozzolanic materials. The physical, chemical, and mineralogical characteristics that control the performance of these calcined clays as SCMs are still under discussion. Few in-depth studies of the behavior of these characteristics have been reported. The origin and geological history of raw materials, as well as their impact on the thermal activation and performance as SCM, are not well understood or, in some cases, have not been considered. The objective of the current work, therefore, was to study multicomponent clays from metamorphic rocks with low-grade kaolinite (<50%) from a tropical region of Colombia for possible use as SCMs. The clay deposit was identified by geological exploration techniques and classified in depth according to horizons of the weathering profile. The samples were extracted from the first 50 m of the deposit and characterized physically, chemically, and mineralogically; they were calcined at 650, 750, and 850°C; their degree of alteration was estimated by the Chemical Index of Alteration (CIA); and their performance as an SCM was evaluated by the Strength Activity Index (SAI) and Frattini test. As a main result, a relationship was found between the weathering profile of the deposit and the CIA of raw clays, which confirmed the high weathering and degree of alteration of the parent rock in the deposit (weathered rock and residual soil with a CIA > 80%). Furthermore, pozzolanic (physical and chemical) tests demonstrated the potential use of calcined clays from this deposit as SCMs, as well as their thermal activation at low temperature (≤750°C). In addition, the pozzolanic activity increased with the kaolinite/(muscovite+illite+vermiculite) ratio mainly, and, in turn, the thermal activation temperature increased with the mica and type 2:1 clay content.

As they were just coming out of the COVID-19 pandemic, Southern European nations were confronted with a new shock to their economies – this time in the form of a steep rise in prices. This article describes and typifies the social policy responses and measures adopted in Greece, Italy, Portugal and Spain in response to rising inflation. We find that Southern European (SE) governments have put forward a substantive fiscal response – which compares well with that of its neighbours, and even with the previous crisis. The thrust of the response was targeted at limiting the pass-through of international energy prices to consumers. This was complemented, albeit to a lesser degree, with direct support to families. Nevertheless, we do find important differences concerning the weight given to (traditional) welfare transfers, and the role given to indexation mechanisms and wage increases. We also find important continuities with the model of crisis-response adopted during the pandemic.

Lateritic weathering kaolinites have been characterized in situ and differentiated for the first time by means of infrared microspectroscopy (IRMS). Four classical OH-stretching bands have been observed in the Fourier transform infrared (FTIR) spectra, at 3695, 3668, 3650 and 3620 cm−1, denoted ν1, ν2, ν3 and ν4, respectively, plus a band at 3595 cm−1 associated with the octahedral substitution of Fe3+ for Al3+. Infrared microspectroscopy of thin-sections of lateritic weathering profiles provides useful information on the types of kaolinite present in different horizons of the profile. The spectra obtained from large well-ordered kaolinite crystals look like those obtained by diffuse reflectance in that, compared with the KBr disk spectra of <2 µm powders, bands at 3668 and 3650 cm−1 are enhanced, and the strong absorption of KBr disks at 3695 cm−1 is replaced by a broad weaker band from 3700–3680 cm−1. In laterites, these large well-ordered kaolinites often exhibit a band at 3595 cm−1 indicative of significant Fe3+ substitution for Al3+ in the structure. The IR microspectra obtained from regions of small, more poorly-ordered kaolinites do not differ so markedly from that of KBr disks. All show enhanced absorption around 3650 cm−1 compared with well-ordered kaolinites, indicating that the disorder is due, at least in part, to domains of dickite-like and/or nacrite-like stacking in their structure. The 3595 cm−1 band is always weaker than that of the well-ordered kaolinite in the same profile. The IRMS data from well-characterized reference kaolinites show that the ratio Aν2/Aν3 is a pertinent IR order index for kaolinites. The larger this index, the larger is the area of the 3595 cm−1 band, and the larger and the more ordered is the kaolinite sample. It is suggested that the diversity of FTIR spectra observed reflects intergrowths of kaolinite-dickite polymorphs, or at least mixtures of high- and low-defect kaolinites which are frequently encountered in the lateritic geosphere rather than pure kaolinitic phases. The largest kaolinites having secondary crystallized in voids are the most ordered and the most ferruginous and have been considered as useful mineralogical tracers of the recent evolution of old lateritic terrains.

The use, in veterinary practice, of a three-dimensional biopolymer matrix (based on chitosan, agarose, and gelatin and doped with halloysite nanotubes) as a vehicle for mesenchymal stem cells (MSCs) to repair bone defects is reported here. The nanocomposite, combined with allogenic adipose-derived stem cells, was suitable for the repair of bone defects in dogs when paired with standard surgery involving metal Kirshner wires. The absence of inflammatory reactions to biopolymer matrices with allogenic stem cells was revealed in the case of an animal prone to inflammatory and allergic reactions. In addition, positive dynamics in the fusion of chronic bone defects without rejection reactions was observed after using a biopolymer matrix with MSCs.

The incorporation of bentonites in aflatoxin-contaminated animal feeds to remedy aflatoxicosis has been tested widely in animal trials. Yet, a large variation in efficacy among samples has been observed which has been attributed to variations in the properties of the clay mineral adsorbents. The objectives of the current study were: (1) to evaluate the mineral and chemical composition of two selected bentonites to find minerals or elements which are potentially of concern; (2) to characterize the aflatoxin B1 (AfB1) adsorption (selectivity, capacity, reversibility, and interlayer accessibility) by the bentonites; and (3) to evaluate the safety and efficacy of selected clays as amendments of aflatoxin-contaminated feed for broiler chickens. The mineral, chemical, and exchange cation composition of the clays were analyzed, and they appeared to be safe for use in feed. The bentonites and their fractions showed that adsorption capacities range from 0.48 to 0.97 mol/kg. The interlayer spaces of both montmorillonites were accessible by AfB1, and the adsorption was irreversible. Three-day old broiler chickens were given clean and high-aflatoxin-concentration (1400 mg/kg) diets with and without the presence of the two bentonites. After three weeks the chickens were sacrificed and biomarkers were evaluated. The presence of aflatoxins reduced the body weight by 58% and resulted in a 25% mortality rate. Adding bentonites 1TX and 4TX increased the body weight of the chickens by 14 and 23%, respectively, but did not improve the mortality rates. The results suggested that selected bentonites could effectively sequester aflatoxins in vivo but did not eliminate the total toxicity present in highly contaminated poultry feed.

Because relatively little information about the crystal-growth process of smectite is available, the process was assessed here by studying the size and shape of nontronite particles synthesized at six different temperatures from 75 to 150°C over a period of 4 weeks.

The morphology of nontronites was studied using low-pressure isotherms of argon adsorption at 77 K, a method which enables the measurement of the basal and edge surface areas of the nontronite particles and of their mean diameter and thickness. During the crystal growth of nontronite, the mean particle length increased whereas their thickness (and the number of stacked layers) did not vary significantly.

A specific two-dimensional crystal-growth process was observed for smectite via the lateral extension of the layers. This process also appears to occur during the growth of neoformed natural smectite.

Millimetric to centimetric green grains widespread in pelagic calcareous sediments recovered at a water depth of3000 m near the Costa Rica margin were studied by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy. Samples were collected, during the Ticoflux II expedition, from the upper bioturbated part of four sedimentary cores (0.13–3.75 m below seafloor). The sediments are calcareous and siliceous nanofossil oozes (coccoliths, diatoms, radiolarians, etc.).

Green grains show generally a concentric zoning with a green rim in which smectite largely predominates over pyrite and a black core in which pyrite is prevalent. Observations by SEM indicate that this zoning results from a progressive inward alteration and replacement of the accumulations of pyrites by smectites. The high-resolution TEM observations of the smectite-pyrite interfaces suggest that the replacement of pyrites by smectite occurs through a dissolution-precipitation process with the formation of a gel. The pyrite matrix is composed of a huge number of very small (0.5–22 µm) pyrite octahedra, a typical texture resulting from the pyritization of organic material in early diagenetic environments.

The accurate mineralogical and crystal chemical characterization of the smectites indicate that they are Fe3+-montmorillonites (Fe3+-rich smectite with a dominant octahedral charge, rarely recorded in the literature). The formation of such Fe3+-montmorillonites forming green grains could be explained by two successive diagenetic redox stages: (1) reducing stage: early pyritization of the organic matter by microbial reduction within reducing micro-environments; (2) oxidizing stage: Fe3+-montmorillonite crystallized in space liberated after dissolution of pyrite connected with the rebalancing of the redox conditions of the micro-environments with the oxidizing surrounding sediments.

Sepiolite-based composites have great potential for application as flame-retardant and thermal-insulation material but their application and development are limited by poor mechanical properties. The objective of the present study was to combine polyvinyl alcohol (PVA) and 3-aminopropyltriethoxysilane (KH-550) with sepiolite (Sep) to improve its aerogel strength. A universal testing machine, thermogravimetry, and microcalorimetry were used to investigate the mechanical properties, thermal-stability, and flame-retardant properties, respectively, of aerogels. The results indicated that KH-550 can enhance effectively the mechanical properties and flame retardancy of aerogels. The compressive modulus of PVA/Sep vs KH-550/PVA/Sep aerogel was 209.28 vs. 474.43 kPa, the LOI index changed from 26.4 to 30.4%. The porosity of the aerogels was > 96% and the density was < 0.05 g/cm3. The thermal conductivity remained at between 0.0340 and 0.0390 W/(m·K), and the aerogel could recover to > 85% after a 50% compressive deformation. These data indicated that Sep-based aerogel would act as a flame retardant and a thermal insulating material with excellent mechanical properties.

The Governing Body of the Church in Wales met twice in 2023, at Venue Cymru in Llandudno on 19–20 April and at the International Conference Centre in Newport on 5–6 September.

Desorption processes of low-molecular-weight compounds from the surface of smectites into the gas phase determine a number of processes, e.g. those involved in drug delivery and the release of herbicides. The desorption has not been investigated thoroughly and is not well understood. The present study was undertaken in order to understand better the factors influencing these desorption mechanisms. Starting with a very pure standard (Na+-rich) montmorillonite (Kunipia-F), which was exchanged against cations with different hydration properties (Ca2+, Li+, phenyltrimethylammonium, hexyltrimethyl-ammonium), the experiments explored the rate of desorption of volatiles with different chemical functionalities (water, ethanol, ethyl acetate, and toluene). The desorption was monitored by thermogravimetry and differential scanning calorimetry under isothermal conditions, and by ramping the temperature at a constant rate. The experiments were compared with numerical calculations based on finite-element methods and with analytical models. These data point to a two-step mechanism where the desorption follows the curve of the equilibrium desorption isotherms of those molecules on the montmorillonite. The bulk-like volatiles (i.e. volatiles with release kinetics close to that of the bulk liquids) were desorbed in a first step. With a decrease in the degree of coverage of the volatile on the montmorillonite, the desorption was increasingly dominated by the strength of interaction between the volatile and the interlayer cations of the montmorillonite.

L-aspartic acid was intercalated into layered double hydroxides by coprecipitation. Two types of well crystallized material were obtained and were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry, differential thermal analysis and polarimetry. Schematic models of two intercalation structures with different basal spacings are given. It is proved that the optical activity of L-aspartic acid is retained during and after the intercalation process.

Two industrial bentonites, IBECO SEAL-80 and TIXOTON TE, have been proposed as potential backfill material in the German Asse salt dome, a test field for the disposal of low- to medium-grade active nuclear waste. Considering the unlikely but possible case of a barrier breakdown with infiltration of a highly concentrated salt brine, the physicochemical stability and material behavior of these bentonites in a saturated salt brine (predominantly MgCl2) at 25°C were studied over the time period of 150 days. The results show that no mineral transformations occurred throughout the duration of the experiments and minor dissolution was only active during the first days. Some chemical properties, namely sorption capability and swelling, were reduced during contact with the salt brine, but could be reversed by removing the salt after treatment. Despite restriction of the CEC in the presence of salt solution, interlayer cation exchange reactions are still active in this environment. The long-term chemical stability of smectite in salt brine is predicted under these low-temperature conditions, but the increased permeability during aggregate formation could lead to physical breakdown of the backfill component.