Clay Substrate Research Articles

Analysis of Substrate, Gastric Content and Nutrient Content of Varuna litterata

Varuna litterata is a secondary freshwater crab found in tidal areas. This crab is caught, its eggs are taken, and it is considered a delicacy. Continuous fishing without any cultivation efforts can cause a decline in the population, leading to extinction. This study aims to determine the characteristics of the habitat substrate, stomach, and nutritional content of V. litterata. The method used in this study is descriptive exploratory. The study was conducted in the Serayu River for four months (October 2023 - January 2024). The observation location was carried out at three stations. The study showed that V. litterata prefers waters with clay sand substrates (75% sand, 25% dust, and 0% clay). This habitat is very suitable for cultivation development, as shown by the population of captured crabs. The results of observations of stomach contents show that this crab is an opportunistic omnivore. This crab has a high nutritional content with an average water content (60.72%), ash (4.57%), fat (0.52%), protein (25.66%), and carbohydrates (8.52%). Further research is essential to understand the reproductive system of V. litterata, its life cycle, and suitable habitats for spawning.

Design and preparation of carissa edulis fruit extract capped with the NiFe2O4/MK30 and oxidation of the organic pollutants under visible light illumination

This study focuses on the synthesis of NiFe2O4 nanoparticles through a green synthesis approach using Carissa edulis fruit extract, which was then anchored onto a montmorillonite (MK30) clay substrate to enhance dye photodegradation. The synthesized nanocomposite was characterized using multiple analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy, BET surface area analysis, vibrating sample magnetometry (VSM), zeta potential measurement, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), and electrochemical impedance spectroscopy (EIS). HR-TEM revealed two distinct morphologies within the composite: cubic and irregular. This study further explored the photocatalytic activity of the composites in degrading contaminants such as rhodamine B and ciprofloxacin. Notably, the NiFe2O4/MK30 composite with 12 % NiFe2O4 loading (12FNM) demonstrated a high potential for generating OH and O−2 radicals, achieving an 89.8 % removal efficiency of Rhodamine B at 10 ppm concentration. Compared with conventional Fenton reactions, the photo-Fenton process achieved a superior removal efficiency of up to 99 %. Radical scavenging studies identified the role of hydroxyl and superoxide radicals in photolysis using benzoquinone, isopropyl alcohol, and EDTA as scavengers. Moving forward, research will focus on developing additional modification strategies to further enhance the photocatalytic efficiency of nickel ferrite.

Reintroduction affects demographic rates but not their interannual correlations in an endangered shrub

Abstract Reintroducing endangered species constitutes an important conservation tool. The performance of reintroduced populations is commonly assessed through mean demographic rates (survival, growth, reproduction and fecundity), but rate correlations are less studied despite their role in extinction risk and trait evolution. In our study, we reintroduced the endangered shrub Vella pseudocytisus subsp. paui in two locations in Spain and compared its demographic performance to that of two natural populations to assess reintroduction success. In both natural and reintroduced sites, we selected sub‐locations with presumably more favourable (clay) vs. more stressful (gypsum) soil conditions. We monitored a total of 1269 individuals in natural (12 years) and reintroduced populations (6 years) and compared their mean demographic rates and the within‐individual rate correlations between years. In clay substrate, mean demographic rates of the natural and the reintroduced population were similar, suggesting a successful reintroduction. In contrast, the reintroduced population in gypsum showed higher reproduction and fecundity than the natural population, but lower survival and growth. Contrary to mean demographic performance, interannual correlations among demographic rates did not vary between natural and reintroduced populations. While reproduction in a given year was positively correlated with later growth and later reproduction, growth in a given year had some negative consequences in subsequent plant performance, especially in gypsum substrate. Synthesis and applications. Our study shows that stressful conditions may trigger individual‐level trade‐offs in resource allocation and population‐level compensation among demographic rates. Demographic shifts arising from reintroductions in different environmental conditions may be considered by managers as a potential mechanism of resilience against environmental change. Finally, the similarity in rate correlations among sites suggests that information about correlations, which can be relevant when focusing conservation efforts, may be extrapolated from natural to reintroduced populations. This might be particularly reliable for species where rate correlations are demographically influential, such as those living under generally stressful conditions, or lacking buffering mechanisms for demographic variation.

Removal of perfluoroalkyl acids and precursors with silylated clay: Efficient adsorption and enhanced reuse

Organically modified clays (organoclays) have been considered effective adsorbents for the treatment of per- and polyfluoroalkyl substances (PFAS). However, the stability of organoclays prepared through the conventional cation exchange approach has been a major concern for their practical application. In this study, we reported the development of a new organically functionalized clay by grafting pillared clay substrate with an organosilane through covalent bonding. The performance of the silylated clay (QAG-ZrMT) was systematically compared with an organoclay prepared from ion exchange (HDTMA-ZrMT) for the adsorption of two legacy perfluoroalkyl acids: perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), and two precursor compounds 5:3 fluorotelomer carboxylic acid (5:3FTCA) and 6:2 fluorotelomer sulfonic acid (6:2FTS). Compared to HDTMA-ZrMT, QAG-ZrMT showed substantially improved performance for adsorption of less hydrophobic PFAS (e.g., 5:3FTCA), which could be related to the stronger electrostatic interactions between PFAS and QAG-ZrMT than HDTMA-ZrMT. More importantly, QAG-ZrMT could be conveniently regenerated and reused for multiple cycles with robust performance. In contrast, HDTMA-ZrMT almost completely lost its capacity for PFAS removal after regeneration, due to the loss of organic functional groups during solvent regeneration. Results can shed light on the design of efficient and regenerable organoclay adsorbents for remediation of PFAS-contaminated water matrices.

Preparation and investigation of TbCrO3/montmorillonite-K10 nanocomposite electrode for electrochemical hydrogen storage application

The limited resources of fossil fuels and the increase in human’s demand for energy have made the use of alternative green energies like hydrogen very important. In this regard, achieving superior specific capacity and high-performance electrochemical hydrogen storage requires the structural design and development of highly active electrode material with cooperative influence of “spillover”, “redox”, and “physisorption” mechanisms. The aim of this report is to fabricate a binary TbCrO3/montmorillonite-K10 (TC/MMT) nanocomposite and to skillfully ensure its electrochemical ability for hydrogen storage in 2.0 M KOH electrolyte, for the first time. A facile sonochemical strategy was presented to successfully form uniform orthorhombic TC nanoparticles with varying tetradentate Schiff base ligands derived from salicylaldehyde and relative diamines as well as the molar ratio of H2Salbn to Tb3+. Characterization analyses displayed that the nucleation and growth process of TC samples can be well controlled by a molar ratio of H2Salbn:Tb3+ = 1:1 within the range of 17–72 nm. Furthermore, implementation of a well-organized MMT-based nanocomposite with various amounts of nano-TC perovskites was evaluated on the structural and electrochemical features. The greatly enhanced hydrogen storage capacity of TC/MMT nanocomposites was acquired as 734.3 mAh/g after 15 cycles, when 10.0 % of perovskite oxide is induced by MMT layers. Moreover, architecture of pristine TC and MMT electrodes possessed a 936.87 and 341.52 mAh/g discharge capacities at the same situation. These merits allow a promising potential application of the nanocomposite electrodes containing rare-earth chromite oxide and clay substrates in electrochemical energy-storage devices.

Substrate Matters: Ionic Silver Alters Lettuce Growth, Nutrient Uptake, and Root Microbiome in a Hydroponics System.

Ionic silver (Ag+) is being investigated as a residual biocide for use in NASA spacecraft potable water systems on future crewed missions. This water will be used to irrigate future spaceflight crop production systems. We have evaluated the impact of three concentrations (31 ppb, 125 ppb, and 500 ppb) of ionic silver biocide solutions on lettuce in an arcillite (calcinated clay particle substrate) and hydroponic (substrate-less) growth setup after 28 days. Lettuce plant growth was reduced in the hydroponic samples treated with 31 ppb silver and severely stunted for samples treated at 125 ppb and 500 ppb silver. No growth defects were observed in arcillite-grown lettuce. Silver was detectable in the hydroponic-grown lettuce leaves at each concentration but was not detected in the arcillite-grown lettuce leaves. Specifically, when 125 ppb silver water was applied to a hydroponics tray, Ag+ was detected at an average amount of 7 μg/g (dry weight) in lettuce leaves. The increase in Ag+ corresponded with a decrease in several essential elements in the lettuce tissue (Ca, K, P, S). In the arcillite growth setup, silver did not impact the plant root zone microbiome in terms of alpha diversity and relative abundance between treatments and control. However, with increasing silver concentration, the alpha diversity increased in lettuce root samples and in the water from the hydroponics tray samples. The genera in the hydroponic root and water samples were similar across the silver concentrations but displayed different relative abundances. This suggests that ionic silver was acting as a selective pressure for the microbes that colonize the hydroponic water. The surviving microbes likely utilized exudates from the stunted plant roots as a carbon source. Analysis of the root-associated microbiomes in response to silver showed enrichment of metagenomic pathways associated with alternate carbon source utilization, fatty-acid synthesis, and the ppGpp (guanosine 3'-diphosphate 5'-diphosphate) stringent response global regulatory system that operates under conditions of environmental stress. Nutrient solutions containing Ag+ in concentrations greater than 31 ppb in hydroponic systems lacking cation-exchange capacity can severely impact crop production due to stunting of plant growth.

Оценка эффективности применения микробиологического препарата при выращивании травосмеси Bromus inermis и Elymus fibrosus на малопригодных субстратах

Abstract. The purpose of the work was to evaluate the effect of the microbiological preparation BIOR-AV on the structure, morphological characteristics and productivity of the grass mixture of Bromus inermis Leyss. and Elymus fibrosus (Schrenk) Tzvelev during the reclamation of planned clay dumps. Methods. Studies of experimental and control crops planted in 3 replicates within an area of 25 m2 were carried out during the growing seasons of 2001–2010. Projective cover and above-ground phytomass were determined on survey plots of 0.5 × 0.5 m; in each option, at least 15 plots were laid out. The dynamics of the morphological structure of vegetative and generative shoots was analyzed, and an agrochemical analysis of the substrate was carried out. Results. The positive effect of using the microbiological preparation during accelerated reclamation of dumps without applying fertile soil on the height, weight and length of leaves of vegetative and generative shoots; the number and size of structural elements of the inflorescences of the tested cereals (the length of the inflorescence, the number of branches in the inflorescence, the number of flowers, the number of spikelets, the weight of the inflorescence), and the sowing qualities of the seeds has been established. An increase in the content of the main elements of mineral nutrition in the substrate with the addition of the microbiological preparation: total nitrogen (1.6 times), available phosphorus and potassium (2 times), humus (5 times), as well as an increase in pH values from acidic to slightly acidic was revealed. The scientific novelty of the work: for the first time, in the conditions of the Middle Urals, monitoring studies of the effectiveness of the microbiological preparation on the structure, morphological parameters and productivity of a grass mixture of B. inermis and E. fibrosus were carried out on unsuitable clay substrates.

Role of Clay Substrate Molecular Interactions in Some Dairy Technology Applications.

The use of clay materials in dairy technology requires a multidisciplinary approach that allows correlating clay efficiency in the targeted application to its interactions with milk components. For profitability reasons, natural clays and clay minerals can be used as low-cost and harmless food-compatible materials for improving key processes such as fermentation and coagulation. Under chemical stability conditions, clay materials can act as adsorbents, since anionic clay minerals such as hydrotalcite already showed effectiveness in the continuous removal of lactic acid via in situ anion exchange during fermentation and ex situ regeneration by ozone. Raw and modified bentonites and smectites have also been used as adsorbents in aflatoxin retention and as acidic species in milk acidification and coagulation. Aflatoxins and organophilic milk components, particularly non-charged caseins around their isoelectric points, are expected to display high affinity towards high silica regions on the clay surface. Here, clay interactions with milk components are key factors that govern adsorption and surface physicochemical processes. Knowledge about these interactions and changes in clay behavior according to the pH and chemical composition of the liquid media and, more importantly, clay chemical stability is an essential requirement for understanding process improvements in dairy technology, both upstream and downstream of milk production. The present paper provides a comprehensive review with deep analysis and synthesis of the main findings of studies in this area. This may be greatly useful for mastering milk processing efficiency and envisaging new prospects in dairy technology.

Distribution pattern of benthos based on substrate in the mangrove area of Labuhan Haji District, South Aceh Regency

Mangrove areas can function as habitats for spawning, rearing, and foraging for various species in them. Benthos is an organism that lives on the bottom of the water. Research on benthos distribution patterns based on substrate was carried out with the aim of studying benthos species, types of substrates, and analyzing benthos distribution patterns based on substrates in Labuhan Haji District, South Aceh District, Aceh Province. The method used in this study is the method of observation and field work. The benthos distribution pattern based on the substrate was calculated using the morphic index. Identification results found 31 species of benthos consisting of 3 classes, namely gastropods with 7 orders, bivalves with 4 orders, and malacostraca with 1 order and the type of substrate analyzed obtained 4 types of substrate namely dusty loam, sandy loam, silt and sand. The benthos distribution pattern based on the substrate obtained 2 categories, namely uniform on sandy loam and sandy clay substrates, and clustered on dusty and dusty clay substrates.Keywords:MangrovesBenthosSubstrate TypeSpread patternLabuhan Haji

Adsorption of per- and polyfluoroalkyl substances (PFAS) by ionic liquid-modified clays: Effect of clay composition and PFAS structure

Organically modified clays have been reported as a promising class of adsorbents for the treatment of per- and polyfluoroalkyl substances (PFAS), a group of emerging contaminants of widespread concerns. Here, we reported the development and evaluation of ionic liquid (IL)-modified clays prepared with various natural clays to explore the role of clay substrate in the adsorption of eight persistent perfluoroalkyl acids (PFAAs). Based on detailed adsorption isotherm study, we found that the adsorption capacities of PFAAs were closely related to the cation exchange capacities of the raw clays and correspondingly the IL loadings of the modified clays. Additionally, a positive correlation was observed between the adsorption affinity of PFAAs onto IL-modified clays and the octanol–water distribution coefficient (Dow) of PFAAs. Adsorption free energy analysis suggested that both electrostatic and hydrophobic interactions played important roles in the adsorption of PFAAs onto IL-modified clays. Although electrostatic interactions were more predominant, the contribution of hydrophobic interactions increased with the increasing carbon number of perfluoroalkyl moiety of PFAAs, resulting in more favorable adsorption of long-chain PFAAs than their short-chain homologs. The performance of IL-modified clays was further demonstrated for the removal of PFAA mixtures under environmentally relevant conditions. Overall, results of this work can provide important insights into guiding the design of organically modified clay adsorbents for PFAS treatment.

Gastrochaenolites as Palaeoenvironmental Information Traps: The Case of the Tholos of La Pastora (Valencina de la Concepción, SW Spain)

ABSTRACT In the Mio-Pliocene calcareous sandstone slabs used as capstones at La Pastora tholos in the Copper Age megasite of Valencina de la Concepción-Castilleja de Guzmán (SW Spain), marine bioerosion structures produced in the 3rd millennium BCE were recognised. In this work, we focus on the perforations made by the lithophage bivalve Petricola lithophaga, called Gastrochaenolites, specifically on its functionality as a ‘trap’ of sediment of the environment where they were produced and of which there are no observable outcrops. The microfaunal content consisting of planktonic and benthic foraminifera as well as ostracods was studied. It was possible to infer the palaeoenvironmental conditions of the place where the slabs were quarried, c. 4700–4600 years ago, which correspond to a wide marine bay. The presence of benthic foraminifera like Astrononium stelligerum, Elphidum crispum, Ammonia beccarii and ostracods like Loxoconcha elliptica and Cytherois fischeri implies that the sector of the bay had a water temperature of no more than 20°C, a bathymetry between 0 and 25 m of depth. Also, episodes of fluvial influence caused a variation in water salinity between 30 and 35‰, attested by the presence of euryhaline species of ostracods from low energy environments and clay substrates, thus confirming estuarine conditions.

Sepiolite-metal organic framework-iron oxide catalyst for degradation of Rhodamine B using Fenton-like process

BackgroundThe catalytic degradation of harmful organic pollutants, i.e., Rhodamine B (RhB), is very valuable from the environmental viewpoint. In this way, the design and fabrication of an effective heterogeneous catalyst has a prospect in the treatment of dye containing effluents. MethodsThe magnetic catalyst was prepared by first successfully deposition of the MOF(801) material on clay substrate using a solvothermal process to form Sep-MOF(801) and subsequent formation of ultrafine Fe3O4 nanoparticles via a simple chemical precipitation route on the surface of Sep-MOF(801) to prepare Sep-MOF(801)-Fe3O4. The morphological and structural characters of the Sep-MOF(801)-Fe3O4 nanocomposite were explored using FT-IR, BET, XRD, TEM, SEM, EDX, VSM and XPS methods. Significant findingsExperimentally, the RhB degradation efficiencies at various Fenton-like systems abided by the order of Sep-MOF(801)-Fe3O4/H2O2+NH2OH > Fe3O4/H2O2+NH2OH > Sep-MOF(801)/H2O2+NH2OH > Sep/H2O2+NH2OH > MOF(801)/H2O2+NH2OH > H2O2+NH2OH. The presence of NH2OH as reducing agent can further improve the RhB degradation performance and led to less consumption of H2O2. Under the optimum experimental conditions, 50 mg L−1 RhB was completely degraded in 12 min. In addition, the reusability of the Sep-MOF(801)-Fe3O4 catalyst was investigated after six repeated catalytic cycles.

Hydrogeomorphic Response of Charcoals During River Transits and Its Impact on the Carbon Cycle

AbstractNatural or anthropogenic‐induced biomass burning produces large amounts of charcoals, which enter riverine or lacustrine systems mostly via surface runoff processes. Charcoal storage and cycling within large riverine systems can play a crucial role in mediating long‐term carbon sink across transient reservoirs, thereby influencing the global carbon budget. However, natural processes governing the transport and storage of charcoal particles in large terrestrial reservoirs such as the Indo‐Gangetic region still remain unknown. To understand charcoal movement and accumulation across upland and lowland transient reservoirs, we characterized spatial distribution and morphology of different charcoal forms (>125 μm and <125 μm) from bedload and floodplain sediments of the Yamuna sub‐basin (YSB), India. Both >125 μm and <125 μm charcoal forms in bedload and floodplain sediments did not exhibit similar spatial distribution patterns, indicating the segregation of charcoal particles influenced by variable flow regimes. Attrition with sediments breaks down fragile charcoals (leaves) quickly compared to the woody forms, resulting in dominant woody microforms in transient deposits. Higher stream power and limited stable bedform development in upland mountainous regions restrict charcoal storage. During lowland riverine transits, reduced stream power conditions allow increased floodwater inundation and finer clay substrate availability, facilitating an exponential increase in charcoal storage. However, increased discharge from peninsular rivers into the YSB leads to erosion and redistribution of sediment, including charcoal particles, and reduced charcoal storage in lowland transient areas. Such diverse dispersal pathways and fate of charcoal particles across riverine transits highlight the influence of regional hydrogeomorphic processes on the overall carbon cycle within transient reservoirs.

Synthesis of a chitosan-clay nanomembrane by pH control and its thermal stability in aqueous environments

Nanofiltration is a promising technology for the treatment of industrial effluents containing organic contaminants and large divalent ions. The development of green nanomembranes is hence crucial for advancing this technology. This work aims to synthesize a novel chitosan-montmorillonite (CTS-MMT) nanomembrane concerning pH effects and to evaluate its structural stability under a wide range of operating temperatures in aqueous solution. Molecular dynamics method is conducted here and the INTERFACE-PCFF force field was employed in the biopolymer-organic system. Results show that water and counterions play a hindering role in the coating process. The higher protonation rate of chitosan can achieve higher adhesiveness and a more uniform distribution on the MMT surface after complete drying. This behaviour is due to the CTS-MMT interaction, mainly generated by -NH3+ via electrostatic and hydrogen bonding interactions, while OH and NH2 groups exhibit negligible contributions. Both water-induced peeling as well as temperature-dependent peeling were analyzed basically according to the adhesion rate of NH3+ groups. Water evaporation is observed at around 550 K and no decisive desorption of chitosan from the clay substrate can be found even at extremely high temperatures up to 800 K. The high thermal stability of the CTS-modified organoclay nanomembrane in water proves that they will not generate secondary pollutants. This study can therefore provide insight into the fabrication and design of the proposed new type of membrane within clay nanocomposites.

Identification of mangrove species based on substrate characteristics in Borimasunggu Village, Labakkang District, Pangkep Regency

Mangroves are coastal ecosystems that have many benefits, including the ecological benefits of being a source of nutrients for marine life (aquatic biota) and a source of food for land biota. This study aimed to determine the species composition and community structure of mangrove vegetation based on the substrate type and the relationship between mangrove density and substrate texture in Borimasunggu Village, Labakang District. This research was carried out from July to August 2021 in the Borimasunggu Village, Labakkang District, Pangkep Regency. The research method is purposive random sampling which is divided into 3 stages. At each station, 3 transects/plots are determined. The study results found 3 mangrove species in Borimasunggu Village, Labakang District, based on the type of substrate, namely Rhizophora stylosa, Avicennia alba, and Sonneratia alba species. Relative Frequency (RFi) in Borimasunggu Sub-District, Labakang District, was found for all species equally, namely 33.33, the highest relative cover (RCi) was the species Rhizophora stylosa, which was 39.25, and the lowest Relative Coverage (RCi) was the mangrove species Sonneratia alba, which was 26,15. While the highest Significance Value (INP) is the mangrove species Rhizophora stylosa, which equals 148.66%, and the lowest Important Value (INP) is the mangrove species Sonneratia alba, which is equal to 70.59%. The highest relative density (RDi) was found in the mangrove species Rhizophora stylosa, which was 74.07% with a clay substrate type, followed by Avicennia alba 14.81% and Sonneratia alba 11.11% with a dusty clay substrate types.

DENSITY AND DISTRIBUTION PATTERNS OF FULL-BLOODED CLAM (GELOINA EXPANSA; MOUSSON, 1849) IN MANGROVE ECOSYSTEMS

Geloina expansa is a clam found in mangrove forests. The high level of public consumption and high economic value, is suspected as the cause of overfishing. It is not impossible that continuous harvesting will result in a decrease in the population of G. expansa. The habitat of G. expansa has experienced a lot of land conversion and this will result in a decrease in the natural carrying capacity of its habitat. The purpose of this study was to determine the distribution and density, distribution pattern and size distribution of the population of G. expansa based on the ecology of its habitat in West Malangke waters. The method was carried out randomly, the transect was placed in a 5x5 m2 sample plot with 3 replications and collected directly by hand. Sampling was carried out on each plot at the lowest ebb. Environmental parameters measured in the field included salinity, temperature and substrate while parameters measured in the laboratory were total organic matter (TOM). The density value of G. expansa in the intertidal zone was 9.90 ind/m2 while in the subtidal zone it was 0.78 ind/m2. The distribution pattern found in the intertidal and subtidal zones is clustered. The size distribution of G. expansa in the intertidal zone found that the dominant G. expansa was adult size, and the lowest was in the old size class while in the subtidal zone the dominant size was young and the lowest was in the old size class. Zone and type of substrate affect the existence of G. expansa. G. expansa was found more in the intertidal zone than in the subtidal zone and clay-type of substrates were a determining factor for the presence of full-blooded clams while clay and sand-type substrates were limiting factors for the presence of full-blooded clams.

Fracture properties of thin brittle MTM clay coating on ductile HEC polymer substrate

Thin clay coatings can be deposited from water dispersions for the purpose of improved gas barrier properties and fire retardancy of polymeric materials. Mechanical properties of the coatings are difficult to assess, since they are very thin (≈1µm). In-situ tests using a micro tensile stage in a scanning electron microscope reveal a thickness-dependent microcracking mechanism, and Weibull parameters for coating fracture are extracted. Complex fracture events are identified, related to a weak clay coating-polymer substrate interface. A micromechanical finite element formulation provides values of 5 MPa for interfacial shear strength and 1 J/m2 for interfacial fracture toughness. From the multiple cracking behavior of the clay coating, a clay strength ≈ 225 MPa is estimated by the Weibull strength parameter from fragmentation diagrams. The method may be extended to other combinations of brittle coating-ductile substrates.

Who venerated the ancestors at the Petit-Chasseur site? Examining Early Bronze Age cultic activities around megalithic monuments through the archaeometric analyses of ceramic findings (Upper Rhône Valley, Switzerland, 2200–1600 BC)

Through the analyses of recovered pottery, this study explores the social dimension of an ancestor cult developed at the Petit-Chasseur megalithic necropolis (Upper Rhône Valley, Switzerland) during the Early Bronze Age (2200–1600 BC). The jar votive offerings and domestic pottery from settlement sites were characterized using a range of spectroscopic and microscopic techniques. Acquired archaeometric data allowed identification of six ceramic fabrics and two types of clay substrate—illite- and muscovite-based—which were used in pottery production. The present article discusses the pottery composition in the light of natural resources available in the region, thus shedding light on raw material choices and paste preparation recipes. The Early Bronze Age people that lived in the Upper Rhône Valley seem to have shared a common ceramic tradition, partly inherited from the previous Bell Beaker populations. The compositional correspondence between the jar offerings and domestic pottery revealed that the majority of the known Early Bronze Age groups partook in cultic activities at the Petit-Chasseur megalithic necropolis.

Micromorphological soil assessment in abandoned quarry dumps of the Central Caucasus, Russia

This study compared the micromorphological and agrochemical metrics in soils from the quarry dumps and zonal soils, the Central Caucasus. Soil micromorphological investigations are important tool for evaluation of soil dynamics after anthropogenic impacts on terrestrial ecosystems. The results showed that the carbon content in the primary soil of the sand and gravel quarries was lower than that in the reference soil. The differences detected were statistically significant for both the Urvan plot soils (t = 11.95; p = 0.000) and the Progress plot soils (t = 18.73; p = 0.000). In contrast, in the quarry with clay bottom substrate (Gerpegezh), no significant difference was found between the reference and postmine soils. The reference soil around the sand and gravel quarries was slightly more acidic than the primary soil. In the clay quarry, the primary soil was more acidic with a strong acidic value, while the reference soil was neutral. The difference of nutrients (P, K, NH4+, NO3-) between the primary and reference soils were negligible. The only exception was the NO3- content in the reference soil of Progress settlement, where it was significantly higher (t = 4.19; p = 0.002) than in the original soil of the site. No difference was observed for the mineral component of the primary soil. Investigation of key zonal soils of the region. Zonal Caucasus soils: Phaeozem Gleiyc, Phaeozem and Umbric Retisol are different in terms of micro texture. Thus, Phaeozem Gleiyc characterizes by microstructure composed by primary angular mineral forms. Phaeozem and Retisol demonstrated formation of biogenic structure with alteration of mineral particles. Data obtained show that rapid self revegetation of the quarries results in initialization of primary soil formation and transformation of the soil microstructure and organization on the micro level.

Electrical conduction mechanism in carbon-ceramic composites

Carbon-ceramic composites (C/Cer) have been prepared by chemical vapor deposition of coal tar pitch onto clay substrates and characterized by thermogravimetric analyses, powder X-ray diffraction, Raman spectroscopy, and scanning and transmission electron microscopies (SEM and TEM). The study of the dc electrical conductivity, together with the determination of the Hall voltage sign, proves that such C/Cer composites are n-type semiconductors. Our results demonstrate that: 1) the mechanism of electrical conduction of C/Cer semiconductors proceeds through the pathways expected for amorphous solids (ie. variable-range hopping and heat-activated pathways at low and high temperatures, respectively); and 2) their transport properties are strongly dependent on the clay components, as evidenced by microscopy experiments.