Search Results (565)

The Junggar Basin contains a large amount of coal resources and is an important coal production base in China. The coal seam in Zhundong coalfield has a large single-layer thickness and high content of inertinite, but large particle Fe-sulphide minerals are associated with coal seams in some mining areas. A series of economic and environmental problems caused by the combustion of large-grained Fe-sulphide minerals in coal have seriously affected the economic, clean and efficient utilization of coal. In this paper, the ultra-thick coal seam of the Xishanyao formation in the Yihua open-pit mine of the Zhundong coalfield is taken as the research object. Through the analysis of coal quality, X-ray fluorescence spectrometer test of major elements in coal, inductively coupled plasma mass spectrometry test of trace elements, SEM-Raman identification of Fe-sulphide minerals in coal and LA-MC-ICP-MS test of sulfur isotope of marcasite, the coal quality characteristics, main and trace element characteristics, macro and micro occurrence characteristics of Fe-sulphide minerals and sulfur isotope characteristics of marcasite in the ultra-thick coal seam of the Xishanyao formation are tested. On this basis, the occurrence state and genesis of large particle Fe-sulphide minerals in the ultra-thick coal seam of the Xishanyao formation are clarified. The main results and understandings are as follows: (1) the occurrence state of Fe-sulphide minerals in extremely thick coal seams is clarified. The Fe-sulphide minerals in the extremely thick coal seam are mainly marcasite, and concentrated in the YH-2, YH-3, YH-8, YH-9, YH-14, YH-15 and YH-16 horizons. Macroscopically, Fe-sulphide minerals mainly occur in three forms: thin film Fe-sulphide minerals, nodular Fe-sulphide minerals, and disseminated Fe-sulphide minerals. Microscopically, they mainly occur in four forms: flake, block, spearhead, and crack filling. (2) The difference in sulfur isotope of marcasite was discussed, and the formation period of marcasite was preliminarily divided. The overall variation range of the δ³⁴S value of marcasite is wide, and the extreme values are quite different. The polyflake marcasite was formed in the early stage of diagenesis and the δ³⁴S value was negative, while the fissure filling marcasite was formed in the late stage of diagenesis and the δ³⁴S value was positive. (3) The coal quality characteristics of the thick coal seam were analyzed. The organic components in the thick coal seam are mainly inertinite, and the inorganic components are mainly clay minerals and marcasite. (4) The difference between the element content in the thick coal seam of the Zhundong coalfield and the average element content of Chinese coal was compared. The major element oxides in the thick coal seam are mainly CaO and MgO, followed by SiO₂, Al₂O₃, Fe₂O₃ and Na₂O. Li, Ga, Ba, U and Th are enriched in trace elements. (5) The coal-accumulating environment characteristics of the extremely thick coal seam are revealed. The whole thick coal seam is formed in an acidic oxidation environment, and the horizon with Fe-sulphide minerals is in an acidic reduction environment. The acidic reduction environment is conducive to the formation of marcasite and is not conducive to the formation of pyrite. (6) There are many matrix vitrinite, inertinite content, clay content, and terrigenous debris in the extremely thick coal seam. The good supply of peat swamp, suitable reduction environment and pH value, as well as groundwater leaching and infiltration, together cause the occurrence of large-grained Fe-sulphide minerals in the extremely thick coal seam of the Xishanyao formation in the Zhundong coalfield. Full article

Root lesion nematodes (RLNs) are major plant parasites causing significant global yield losses in a wide range of crops. Current management strategies largely depend on synthetic nematicides, which raise environmental and human health concerns due to their broad-spectrum toxicity and persistence in the ecosystem. Volatile allelochemicals offer a promising, environmentally safer alternative due to their biodegradability and lower toxicity to mammals. In this study, we assessed the nematicidal activity of five allelochemical volatiles—dimethyl sulphide (DMS), dimethyl disulphide (DMDS), trans-cinnamaldehyde (TCA), trans-2-decenal (T2D), and trans-2-undecenal (T2U)—against Pratylenchus penetrans, using direct-contact bioassays, in comparison with the conventional nematicide oxamyl. Additionally, we assessed their environmental behaviour and toxicity profiles through in silico modelling. At 1 mg/mL, TCA, T2D, and T2U exhibited strong activity against P. penetrans, outperforming oxamyl by up to 1.6-fold, while DMS and DMDS showed reduced activity. The environmental risk assessment revealed that these compounds have a lower predicted persistence and bioaccumulation compared with oxamyl or fluopyram, a new generation nematicide. Though these findings boost the potential of these compounds as sustainable alternatives for RLN management, field validation and testing with non-target organisms remain necessary for the development of biopesticides. Nevertheless, this study emphasizes the need for an integrated risk-based assessment in the selection of nematicidal agents, warranting efficacy as well as environmental safety. Full article

This study characterises low-grade copper ore tailings from a conventional flotation circuit to evaluate their feasibility for further processing. A suite of advanced analytical techniques, such as X-ray fluorescence (XRF), inductively coupled plasma (ICP), X-ray diffraction (XRD), and the quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), was employed to assess the elemental, chemical, and mineralogical composition of the tailings. Chalcopyrite was identified as the dominant copper-bearing mineral phase, predominantly locked within iron oxides and silicate gangue minerals. The QEMSCAN results showed that chalcopyrite was only partially liberated, which highlights the complex mineral intergrowths that hinder efficient recovery. Based on the mineralogical characteristics, the applicability of various processing techniques, including conventional froth flotation, advanced flotation methods [including Hydrofloat^TM, Jameson, and the Reflux Flotation Cell (RFC)], magnetic separation, and gravity separation, was evaluated. Overall, this study indicates that incorporating HydroFloat™, the Jameson Cell, and the RFC into the flotation circuit could greatly improve copper recovery from tailings. This study also identified rare earth elements (REEs) as potential by-products of copper recovery, so it is an additional opportunity for resource recovery. This paper contributes to sustainable mining practices and resource optimization by highlighting the characteristics and recovery of valuable minerals from tailings. Full article

This study explores Bayesian Ridge Regression and PyMC-based probabilistic modelling to predict the cumulative grade of gold based on key operational variables in gold flotation. By integrating prior knowledge and quantifying uncertainty, the Bayesian approach enhances both interpretability and predictive accuracy. The dataset includes variables such as crusher type, particle size, power, time, head grade, and collector type. Comparative analysis reveals that PyMC outperforms traditional Sklearn models, achieving an R² of 0.92 and an MSE of 102.37. These findings highlight the potential of Bayesian models for robust, data-driven process optimization in mineral processing. The higher cumulative gold grade observed for VSI products and PAX collector usage may be attributed to the superior liberation efficiency of VSI, which produces more angular and cleanly fractured particles, enhancing collector attachment. PAX, being a strong xanthate, shows high affinity for sulphide mineral surfaces, particularly under the flotation conditions used, thereby improving selectivity and recovery. Full article

Seagrass meadows play a critical role in biogeochemical cycling, especially in nitrogen and sulphur processes, driven by their associated microbiome. This study provides a novel functional analysis of microbial communities in seagrass (Zostera marina) rhizosphere and endosphere, comparing seedlings and mature plants. While nitrogen-fixing bacteria are more abundant in seedlings, mature plants exhibit greater microbial diversity and stability. Sediment samples show higher microbial diversity than roots, suggesting distinct niche environments in seagrass roots. Key microbial taxa (sulphur-oxidizing and nitrogen-cycling bacteria) were observed across developmental stages, with rapid establishment in seedlings aiding survival in sulphide-rich, anoxic sediments. Chromatiales, which oxidize sulphur, are hypothesized to support juvenile plant growth by mitigating sulphide toxicity, a key stressor in early development. Additionally, sulfate-reducing bacteria (SRB), though potentially harmful due to H₂S production, may also aid in nitrogen fixation by producing ammonium. The study underscores the dynamic relationship between seagrass and its microbiome, especially the differences in microbial community structure and function between juvenile and mature plants. The study emphasizes the need for a deeper understanding of microbial roles within the seagrass holobiont to aid with Blue Carbon stores and to improve restoration success, particularly for juvenile plants struggling to establish effective microbiomes. Full article

Regionally metamorphosed, Neoproterozoic stratiform baryte deposits near Aberfeldy in the Grampian Highlands of Scotland, UK, contain barium-poor and barium-rich micas in the host rocks and mineralized strata, respectively. The barium-rich micas include muscovite, biotite, phlogopite, and chromium-bearing muscovite. They occur in schistose metasediments and metabasites, in barium-feldspar rocks, and in small amounts in baryte rock. An extensive study of micas in a range of lithologies using electron-probe micro-analysis found up to 10.86 wt% BaO in muscovite, 5.46 wt% in biotite, and 15.70 wt% in Ba-Cr muscovite, the latter containing up to 9.27 wt% Cr₂O₃. Compositions are comparable with Ba- and Ba-Cr-micas in other metamorphosed Sedimentary Exhalative deposits and barium-rich metasediments worldwide. In one baryte rock sample, disseminated crystals of an exotic Ba-V-Cr mica contain up to 12.33 wt% BaO and 10.82 wt% V₂O₃, compositionally similar to Ba-V micas in the Hemlo lode gold deposit, Ontario. Ba²⁺ incorporation is mainly by coupled substitution with Al³⁺ for K⁺ + Si⁴⁺ in the tetrahedral site. The extent of phengitic (Tschermakitic) substitution is typical of micas in amphibolite-facies metasediments. Similar Fe:Mg ratios in coexisting muscovite and biotite reflect partitioning of iron into sulphides and metamorphic equilibration, with rare exceptions in fine-grained rocks that exhibit millimetre-scale disequilibrium. Full article

For a long time, D-amino acids remained unexplored in mammalian physiology. The technological advances in enantioseparation over the past 50 years have revealed that D-amino acids not only exist in human tissues and fluids but also play important roles in neurotransmission, immune regulation, and cellular proliferation. The present review provides a comprehensive assessment of the role of D-amino acids in cancer, including their endogenous and exogenous production pathways, along with the analytical methodologies used for detection and quantification, from liquid chromatography to biosensors. These methods have underlined how altered levels of D-amino acids can be helpful in early detection, progression, or response to treatment in several malignancies, including gastric, hepatic, colorectal, or breast cancer. The present review also explores how manipulation of D-amino acids can regulate cell proliferation, their mechanisms in cancer regulation, including the modulation of N-methyl-D-aspartate (NMDA) receptors and the production of hydrogen sulphide (H₂S), and the role of specific D-amino acids in cancer onset, immune defence, and protection against chemotherapy-induced toxicity. Finally, several underexplored research directions are outlined, such as potential correlations with gut microbiota composition, the impact of processed food consumption, and the integration of multiomics strategies. Full article

Multiband and nodal-like superconductivity (SC) with s- + d-wave pairing symmetry have implied that tetragonal iron sulphide (FeS) is a distinctive testbed for exploring unexpected electronic correlations. In particular, the low-moment disordered static magnetism originating from the Fe moment leads to the possibility of the coexistence of magnetic orders (MOs) in the superconducting ground state via the tuning of electronic configurations. Here, guided by density functional theory (DFT) calculations, we found that slightly substitutionally doped chromium (Cr) atoms in tetragonal FeS single crystals can induce both considerable d-orbital reconstruction around the Fermi surface and a local magnetic moment of 2.4 µ_B at each doping site, which could highly modulate the SC ground states of the host. On this basis, a clear magnetic transition and reduced anisotropy of SC were experimentally observed. In particular, SC can survive with a doping content below 0.05. This coexistence of SC and MOs suggests strong spin correlations between Cr dopants and the host through exchange coupling. Further, an electronic temperature-related phase diagram of FeS with Cr doping contents from 0 to 0.07 is also provided. These results demonstrate that the continuous injection of local moments can be a controllable method to use to tune collective orders in unconventional iron-based superconductors. Full article

Biological reduction of sulphates has gradually replaced unit chemical processes for the treatment of acid mine drainage (AMD), which exerts a significant environmental impact due to its elevated acidity and high concentrations of heavy metals. Bioremediation is optimally suited for the treatment of AMD because it is cost-effective and efficient. Anaerobic bioremediation employing sulphate-reducing bacteria (SRB) presents a promising solution by facilitating the reduction of sulphate to sulphide. The formed can precipitate and immobilise heavy metals, assisting them in their removal from contaminated wastewater. This paper examines the current status of SRB-based bioremediation, with an emphasis on recent advances in microbial processes, reactor design, and AMD treatment efficiencies. Reviewed studies showed that SRB-based bioreactors can achieve up to 93.97% of sulphate reduction, with metal recovery rates of 95% for nickel, 98% for iron and copper, and 99% for zinc under optimised conditions. Furthermore, bioreactors that used glycerol and ethanol as a carbon source improved the efficiency of sulphate reduction, achieving a pH neutralisation from 2.8 to 7.5 within 14 days of hydraulic retention time. Despite the promising results achieved so far, several challenges remain. These include the need for optimal environmental conditions, the management of toxic hydrogen sulphide production, and the economic feasibility of large-scale applications. Future directions are proposed to address these challenges, focusing on the genetic engineering of SRB, integration with other treatment technologies, and the development of cost-effective and sustainable bioremediation strategies. Ultimately, this review provides valuable information to improve the efficiency and scalability of SRB-based remediation methods, contributing to more sustainable mining practices and environmental conservation. To ensure relevance and credibility, relevance and regency were used as criteria for the literature search. The literature sourced is directly related to the subject of the review, and the latest research, typically from the last 5 to 10 years, was prioritised. Full article

Styrene-butadiene-styrene (SBS)-modified asphalt, a widely utilised binder in pavement engineering, is susceptible to ageing due to the coupling effects of thermo-oxidation, ultraviolet radiation, and humidness. Due to the limited availability of high-quality asphalt resources, recycling aged asphalt has emerged as a vital strategy for addressing resource shortages and reducing environmental pollution. This study investigated the effects of thermal-ultraviolet-humidness coupled ageing on the pavement performance of SBS-modified asphalt, with a specific focus on the hot–wet climates of Guangzhou and Chengdu. Beijing’s standard climate serves as a reference for this study. Additionally, industrial animal oil was chosen as a rejuvenator for aged SBS-modified asphalt. The mechanisms underlying hot–wet coupling ageing and regeneration of SBS-modified asphalt were analysed using Fourier Transform Infrared Spectroscopy (FTIR) and Fluorescence Microscopy (FM). The findings indicate that thermal-oxidation and humidness accelerate sulphide formation, resulting in a marked increase in sulfoxide groups and facilitating the migration of lighter components, ultimately leading to asphalt hardening. Under high-temperature and humidness conditions, the butadiene index (BI) of asphalt decreased by 5.96% in Chengdu and 15.78% in Guangzhou compared to Beijing. The sulfoxide index (SI) and aromaticity index (CI) increased by 3.74% and 3.89% in Chengdu, and by 9.39% and 8.54% in Guangzhou, respectively, confirming the exacerbating effect of humidness on ageing. During the regeneration process, industrial animal oil effectively diluted polar molecules in aged asphalt, resulting in reductions in SI by 38.88%, 36.74%, and 37.74%, and in CI by 63.77%, 62.54%, and 63.11% under ageing conditions in Beijing, Guangzhou, and Chengdu, respectively. Rejuvenation is achieved by replenishing lighter components, thereby promoting the aggregation and swelling of the degraded SBS chains. Full article

The existence of historical pigments databases is important to speed up cultural heritage research. Knowledge of their chemical composition and their manufacture contributes to the study of art history and helps develop accurate conservation-restoration strategies. In this study, a total of nineteen pigments, among which we find silicates (Egyptian blue, natural and synthetic blue ultramarine, green earth and chrysocolla), oxides (natural and synthetic hematite, red and yellow natural ochres, and chromium green), carbonates (natural and synthetic azurite, natural and synthetic malachite, and white lead), sulphides (natural and synthetic cinnabar, and orpiment) and acetates, (verdigris) have been characterized by Fourier Transform Infrared-Spectroscopy in Attenuated Total Reflection (ATR-FTIR) and Diffuse Reflectance (DRIFT) modalities. Considering the latter, there is still a great deal of uncertainty in the interpretation of the different IR vibrational bands. Therefore, a comparative study between these two techniques has been carried out to highlight the potential of DRIFT spectroscopy as a portable and non-destructive technique that allows the differentiation and characterization of historical pigments in the field of cultural heritage. Before performing FTIR analysis, pigments were analysed using X-ray diffraction (XRD) to detect impurities and/or additives in the pigments. Differentiation between natural and synthetic pigments was possible due to the identification of impurities in natural pigments, and manufacture-related compounds or additives in synthetic pigments. Results obtained in this study have proven DRIFT to be a very useful analytical technique for in situ characterization of heritage materials. This study serves as an initial step in clarifying the challenges and uncertainties associated with interpreting spectra obtained through the DRIFT modality. However, the use of other complementary analytical techniques is required. Full article

Paint loss is one of the main forms of deterioration in historical wall paintings, generally restored by the application of chromatic reintegration. In the specific case of outdoor exposed paintings, it is essential to find a binder that will withstand diverse weather conditions. Since chromatic reintegrations have to be compatible with the original painting, fresco paint mock-ups were manufactured and compared to chromatic reintegrations made with an aqueous colloidal dispersion of silica nanoparticles as binder. The physical compatibility was studied by colour spectrophotometry and measurements of static contact angle, gloss, and roughness values, together with a peeling test, stereomicroscopy, and polarised light microscopy. They were also characterised from a mineralogical, chemical, and molecular point of view using X-ray diffraction, X-ray fluorescence and Fourier-transform infrared spectroscopy. The microtexture was studied by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Chromatic reintegrations showed similar roughness and lower gloss values than frescoes, and the nano-silica binder ensured the natural breathability of the wall. Overall, the chemical nature of pigments was highly influential. The reintegrations with silicate-based pigments were more homogenous, with hardly any fissures, while those carried out with sulphide- or oxide-based pigments were severely cracked. The use of verdigris is discouraged due to the lack of affinity between the binder and the pigment. Full article

A Stir Bar Sorptive Extraction-Gas Chromatography-Mass Spectrometry (SBSE-GC-MS) method has been optimized and validated for the determination of eight volatile sulphur compounds in wine distillates: diethyl sulphide (DES), dimethyl disulphide (DMDS), diethyl disulphide (DEDS), 2-thiophenecarboxaldehyde (TC), dibutyl sulphide (DBS), dipropyl disulphide (DPDS), dipropyl sulphide (DPS), and dimethyl trisulphide (DMTS). After optimization by 2⁴ factorial design, the SBSE-GC-MS extraction conditions were as follows: a polydimethylsiloxane twister (10 mm × 0.5 mm), 35 °C as the extraction temperature, 10 mL as the sample volume, 7% (v/v) as the alcoholic grade, 47 min as the extraction time, 10% (w/v) of NaCl, and 1% (w/v) of EDTA (ethylenediaminetetraacetic acid). Under optimal conditions, adequate analytical figures of merit were obtained for eight of the ten compounds initially considered, with low quantification and detection limits and relative standard deviations for inter-twister and inter-day repeatability values ranging from 7.5 to 21.8% and from 7.2 to 27.5%, respectively. The methodology was applied to 34 wine distillates (continuous column distillation and distillation in pot still) elaborated for the production of Brandy de Jerez: 15 aged distillates aged for different periods of time in American oak wood and 19 non-aged distillates. The most significant volatile sulphur compounds were DBS, DMDS, and DPS. The Cluster Analysis (CA) on the volatile sulphur compounds grouped the samples according to the use of sulphur dioxide. In general, lower amounts of volatile sulphur compounds were found in the aged samples, although the high standard deviations obtained highlight that their contents depend on multiple factors related to the elaboration process. Full article

Siderite and baryte are common non-sulphide phases in sedimentary exhalative (SEDEX) deposits, but their formation remains poorly understood. Siderite is important as an exploration vector in some deposits, whereas baryte is important as a S source in some deposits. The past-producing Walton deposit (Nova Scotia, Canada) consists of two ore types: (1) a sulphide body primarily hosted by sideritised Viséan Macumber Formation limestone (0.41 Mt; head grade of 350 g/t Ag, 4.28% Pb, 1.29% Zn, and 0.52% Cu), and (2) an overlying massive baryte body of predominantly microcrystalline baryte (4.5 Mt of >90% baryte). This study used optical microscopy, SEM-EDS, cathodoluminescence (CL), LA-ICP-MS, and SIMS sulphur isotope analysis of siderite and baryte to elucidate their origin and role in deposit formation. Siderite replaces limestone and contains ≤9 wt. % Mn, is LREE-depleted (PAAS-normalised REEY diagrams), and has low (<20) Y/Ho ratios. Sideritisation occurred due to dissimilatory iron reduction (DIR) that led to the breakdown of Fe-Mn-oxyhydroxides and organic matter, as indicated by light δ¹³C_VPBD values and negative Y anomalies. The baryte body is dominated by a microcrystalline variety that locally develops a radial texture and coarsens to a tabular variety; it also occurs intergrown with, and as veins in, massive sulphides. Based on fluid inclusion data from previous studies, the coarser baryte types grew from a hot (>200 °C) saline (25 wt. % NaCl) fluid containing CO₂-CH₄ and liquid petroleum. Marine sulphate δ³⁴S_VCDT values typical of the Viséan (~15‰) characterise the baryte body and some tabular baryte types, whereas heavier (~20‰) and lighter (~10‰) values typify the remaining tabular types. The variations in tabular baryte relate to distinct zones identified by CL imaging and are attributed to the sulphate-driven anaerobic oxidation of methane (SDAOM) and oxidation of excess H₂S after sulphide precipitation. These results highlight the importance of hydrocarbons (methane and organic matter) in the formation of both the siderite and the baryte at Walton and that DIR and the SDAOM can be important contributing processes in the formation of SEDEX deposits. Full article

This study focuses on the olfactometric and chemical characterisation of gaseous and vapour emissions from different crude oils. To investigate this topic, laboratory experiments were set up to obtain comparable gaseous samples: they were estimated in terms of odour concentration (C_od), via dynamic olfactometry, and chemical-specific characterisation. It was found that, even if considered similar in regard to physical properties and chemical composition, the gaseous emissions of different crude oils are significantly different in terms of odorous potential. The observed discrepancy appears to be associated with the presence of volatile organic sulphur compounds (VOSCs), and the highest values of C_od were found in samples containing mercaptans and sulphides. In addition, from the conducted comparison, it appeared that crude odorous potential, in terms of C_od, is not strictly linked to the quantity of the volatile organic compounds (VOCs), H₂S concentration, or a priori knowledge of the percentage of elemental sulphur in the crude; on the contrary, the presence of volatile organic sulphur compounds in the gaseous emissions is the most influential parameter for the odour potential of this matrix. Full article