Attention to carbonate rocks is important in the contemporary geoheritage studies, although the related knowledge is yet to be complete. The consideration of the already published information can ...help to fill this gap. The present study offers interpretation of crinoidal limestones (encrinites) in the terms of geoheritage. A total of 180 literature sources (chiefly articles in international journals) were selected, and their content was analyzed. These sources trace the history of crinoidal limestones from the Ordovician to the Cretaceous; these carbonate rocks were especially common in the Carboniferous and Jurassic. Nonetheless, crinoidal limestones are relatively rare in the world’s sedimentary records, and, thus, they constitute a geoheritage resource. The multiple lines of evidence imply that these rocks can be assigned to ten geoheritage types. The existing works stress their scientific and educational utility. Their touristic importance is linked, particularly to the colors of these rocks, which associate with the common people’s emotions. The collected literature suggests that crinoidal limestones are chiefly a potential, not yet proven geoheritage resource. However, several in-situ and ex-situ geoheritage objects representing these rocks have already been established. Generally, the present study demonstrates a novel perspective for the application of carbonate sedimentology.
Arabidopsis plants grown at low light were exposed to a gradually increasing actinic light routine. This method allows for the discerning of the photoprotective component of NPQ, pNPQ and ...photoinhibition. They exhibited lower values of Photosystem II (PSII) yield in comparison to high-light grown plants, and higher calculated dark fluorescence level (F′ₒ cₐₗc.) than the measured one (F′ₒ ₐcₜ.). As a result, in low-light grown plants, the values of qP measured in the dark appeared higher than 1. Normally, F′ₒ ₐcₜ. and F′ₒ cₐₗc. match well at moderate light intensities but F′ₒ ₐcₜ. becomes higher at increasing intensities due to reaction centre (RCII) damage; this indicates the onset of photoinhibition. To explain the unusual increase of qP in the dark in low-light grown plants, we have undertaken an analysis of PSII antenna size using biochemical and spectroscopic approaches. Sucrose gradient separation of thylakoid membrane complexes and fast fluorescence induction experiments illustrated that the relative PSII cross section does not increase appreciably with the rise in PSII antenna size in the low-light grown plants. This suggests that part of the increased LHCII antenna is less efficiently coupled to the RCII. A model based upon the existence of an uncoupled population LHCII is proposed to explain the discrepancies in calculated and measured values of F′ₒ.
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•The solvent effects on the structural and optical properties of drop-casted MoS2 films are investigated.•The existence of Rabi splitting in the photoluminescence spectra of MoS2 has ...been consolidated.•Dissected the role of electronegativity and surface tension of the solvents on the fruitful exfoliation of MoS2.•Reviewed the literature showing the need for suitable solvents for the liquid phase exfoliation of 2D layered materials.
MoS2, a two-dimensional (2D) layered material with variable bandgap and high stability, can be employed in optical and electronic applications due to its outstanding structural, electrical, and optical properties. The fabrication of MoS2 devices in a facile way is highly inevitable to minimize the time consumption and the cost due to its far-reaching and ceaseless applications. On behalf of their various applications, we have employed sonication-assisted liquid phase exfoliation of MoS2 followed by drop casting the sample in a glass plate for further characterization. MoS2 nanosheets were fabricated by exfoliating bulk MoS2 powder in different solvents with varying surface tension such as Ethanol, Ethylene Glycol (EG), Polyvinyl Pyrrolidone (PVP), Dimethylformamide (DMF), and Dimethyl Sulfoxide (DMSO). The structural and optical properties of the sample were analyzed using XRD, AFM, UV spectroscopy, photoluminescence (Pl) and Raman spectroscopy. The formation of 2D MoS2 film with (002) planes were identified and the thickness of the exfoliated nanosheets was confirmed to be in the nano regime. The optical properties of MoS2 revealed the existence of the spin–orbit coupling and the exciton-plasmon (plexitonic) coupling induced Rabi splitting in the Pl spectra, which increased with a reduction in layer number, and a negative correlation between Pl intensity and Rabi splitting is established. The variation in layer number of MoS2 on different solvents has been studied using the difference in Raman shift between E12g and A1g modes.
We present new mineralogical data of cronstedtite from the Southern-2 orebody, located in the South-Western branch of the Talnakh intrusion (Noril'sk area) composed of massive sulfides in which the ...total amount of oxides and silicates does not exceed 1-3 vol%. The petrographic and mineralogical features of these ores indicated occurrence of fine-grained, fibrous needle like clusters < 50-µm-sized grains of cronstedtite (7.09 Å along its c-axis). This mineral confirmed by a number of analytical techniques (powder X-ray diffraction of balk samples, transmission electron microscopy, scanning electron microscopy, Raman and Infrared spectroscopy). Cronstedtite sporadically contains signals of Al, Ni, Ca and filling the cracks and cavities between sulfides of copper (chalcopyrite) and iron (pyrrhotite, pentlandite). In some cases, cronstedtite contains micron-sized PGM, and associates with magnetite. According the X-ray diffraction analysis of the bulk massive ores besides cronstendtite are established kaolinite, gypsum, calcite, quartz, and cristobalite. The findings of cronstedtite in Noril'sk area have never been mentioned publicly before. Its occurrence is the northernmost known locality in the world. Our results imply that the formation of cronstedtite in the Talnakh intrusion could be possible by the active participation low-temperatures fluids within the relatively near-surface (< 2 km of paleosurface) conditions of intrusion emplacement, in contrast to other deep-seated supergiant Cu-Ni-PGE deposits in the world. The conditions of formation in isolated cavities in fresh pyrrhotite-pentlandite-chalcopyrite massive ores of deep level of the Talnakh intrusion could be favorable for the formation of cronstendtite.
Since the beginning of the 2000s, geoheritage studies have changed from chiefly being applied, tentative, and ephemeral research projects to becoming a full-scale, mainstream direction of geoscience ...investigations ...
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•This work emphasized the preparation and characterization of pure NiO nanostructures and scrutinized the effect of different sintering temperatures on the prepared nanomaterials.•The ...gas sensing capability of synthesized sensors for diverse volatile organic compounds (VOCs) were tested.•The engineering on enhancing the dual selectivity of the sensor for formaldehyde (HCHO) was effectively achieved.•The proposed sensor is shown exceptional gas sensing characteristics for HCHO.
The present research synthesizes pure Nickel Oxide (NiO) nanostructures via a coprecipitation route with exceptional surface modification by temperature treatment. The morphological, structural, elemental and gas sensing tests of the prepared NiO were done carefully. The study unveils the sensing performances of various volatile organic compounds (VOCs), specifically for HCHO. Furthermore, gas sensor testing of prepared samples was carried out at room temperature (RT) and at different concentrations of the target gas. For 100 ppm of target gases, NiO (300 ℃), NiO (500 ℃), and NiO (700 ℃) gas sensors exhibited 83.43, 5616, and 196 gas responses, respectively, at RT. Hence, NiO nanoparticles at 500℃ sintering temperature-based HCHO sensor showed a significant response than other NiO sensors.
New investigations in the Western Caucasus contribute to the understanding of granite pseudokarst (sensu lato) and megaclasts linked to river erosion. A plot on the bank of the Belaya River ...(Mountainous Adygeya, Western Caucasus) was selected to examine diverse and abundant pseudokarst features (small rock basins, hollows, potholes, and channels) and large clasts. Morphological analysis of these features clarifies their general characteristics and genetic interpretations. Pseudokarst features can be classified into two major categories, namely the relatively small (<1 m) and large (>1 m) features. Potholes, which are usually 1–3 m in size, are the most characteristic features occurring on two levels, i.e., on steep walls of the gorge (half-filled with river water) and on slightly inclined surfaces of a terrace-like landform (subaerial exposure). In both cases, their walls from the side of the river are broken. Apparently, these potholes were formed on the river bottom. Subsequent incision of the gorge elevated potholes and the river has eroded them from one side. Apparently, some pseudokarst features are related to macroturbulent flood flows and granite weathering. Due to its scientific uniqueness and aesthetic attractiveness, this granite pseudokarst constitutes geoheritage, which can be exploited for the purposes of geoscience research and geotourism development.
A quenched-in state of thermal equilibrium (at 723 K) in a single crystal of Cr-Fe-Co-Ni close to equal atomic percent was studied. Atom probe tomography revealed a single-phase state with no signs ...of long-range order. The presence of short-range order (SRO) was established by diffuse x-ray scattering exploiting the variation in scattering contrast close to the absorption edges of the constituents: At the incoming photon energies of 5969, 7092, and 8313 eV, SRO maxima that result from the linear superposition of the six partial SRO scattering patterns, were always found at X position. Electronic structure calculations showed that this type of maximum stems from the strong Cr-Ni and Cr-Co pair correlations, that are furthermore connected with the largest scattering contrast at 5969 eV. The calculated effective pair interaction parameters revealed an order-disorder transition at approximately 500 K to a L12-type (Fe,Co,Ni)3 Cr structure. The calculated magnetic exchange interactions were dominantly of the antiferromagnetic type between Cr and any other alloy component and ferromagnetic between Fe, Co, and Ni. They yielded a Curie temperature (TC) of 120 K, close to experimental findings. Despite the low value of TC , the global magnetic state strongly affects chemical and elastic interactions in this system. In particular, it significantly increases the ordering tendency in the ferromagnetic state compared to the paramagnetic one.
Framing geoheritage thematically is important to reveal its diversity. Field investigations in the western part of the Greater Caucasus orogen have allowed for the characterization of three ...localities representing palaeoislands of the Caucasian Sea, which evolved as a semi-enclosed, marginal palaeosea during the Mesozoic. The Gosh locality represents coarse siliciclastics formed on the cliffed shore of the early Induan (Early Triassic) island. The Lipovy locality exhibits conglomerates accumulated on the shore of the early Toarcian (Early Jurassic) island due to erosion of the uplifted crystalline rocks. The Shakhan locality boasts a representative section of cross-bedded sandstones deposited on the alluvial plain of the Hauterivian (Early Cretaceous) island. All these localities are interpreted as geoheritage points, which are parts of larger geosites. Taken together, these points constitute thematic geoheritage sites reflecting the existence of palaeoislands in all Mesozoic periods, which is essential for the understanding of the evolution of the Caucasian Sea during this era. These localities are perfectly accessible, but visiting them requires professional interpretation. The importance of the thematic geoheritage makes its adequate management urgent (particularly, maintenance of geoheritage points, the installation of interpretive panels, and promotion). A geoexcursion route is proposed to facilitate geotouristic exploitation of the characterized geoheritage sites.
The United Nations Educational, Scientific and Cultural Organization (UNESCO) Global Geoparks initiative balances the conservation of geological heritage with its use in purposes of tourism industry. ...However, the resources of geoparks and the current state of their use are yet to be fully understood. The phenomenon of karst (caves, sinkholes, etc.) appears to be a valuable geopark resource because it attracts numerous visitors interested in geo-, eco-, and speleotourism. Of 140 global geoparks, 37% exploit karst resources. These are located chiefly in Europe and Southeast Asia. Just a few geoparks are fully based on karst features and the others use this resource together with other geological heritage resources. Global geoparks tend to emphasize either particular karst elements or entire karst landscapes. Many interesting features (e.g., gypsum and salt karst) are underrepresented in global geoparks. The UNESCO Global Geoparks initiative should become more phenomenon-focused to offer full representation of karst resources. For some countries like Russia and the United States, where geoparks have not been created yet, the consideration of karst resources may provide significant advantages in the strategic development of geopark-based geotourism.
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