Search Results (758)

This study investigated the production of spodumene concentrate and lithium carbonate from a low-grade pegmatite ore containing approximately 0.26 wt.% Li₂O. The ore consisted predominantly of a quartz–feldspar aluminosilicate matrix with dispersed spodumene mineralization, which complicates conventional processing approaches. Preliminary lithium concentration was performed by dense media separation (DMS) using an industrially applicable ferrosilicon-based suspension. The highest separation efficiency was achieved for the −4.0/+2.8 mm fraction, producing a DMS concentrate containing 5.77 wt.% Li₂O with 98% lithium recovery. The obtained spodumene concentrate was subjected to decrepitation at 1000–1100 °C to convert α-spodumene into the more reactive β-modification, followed by sulfation roasting with concentrated sulfuric acid at 250–270 °C. The productive leach solution obtained after water leaching contained up to 12.1 g/L Li₂O. After purification from iron-bearing impurities and precipitation with sodium carbonate, a lithium carbonate product containing at least 98.8 wt.% Li₂CO₃ was obtained. Approximately 53% of the lithium contained in the original ore was recovered into the DMS feed fraction, whereas the overall lithium recovery into lithium carbonate reached about 45% relative to the ore and approximately 70% relative to the concentrate. Full article

Accurate nanoscale displacement readout is essential for optical inertial sensors, precision positioning, and micro-vibration characterization. In this work, we develop a free-space optical heterodyne interferometric readout system for low-frequency nanoscale displacement sensing and establish an SNR-guided adaptive demodulation framework. Two complementary demodulation strategies are integrated: Bessel-function-based frequency-domain sideband extraction for small-amplitude low-SNR motion and IQ quadrature phase tracking for larger-amplitude displacement. The experimentally demonstrated framework maps the applicability regimes of the two methods and enables wavelength-referenced displacement readout over a range from sub-nanometer narrowband detection to 250 nm under the present experimental conditions. The implemented system achieves a repeated-measurement repeatability of 0.40 nm under a 10 Hz excitation condition, and spectral SNR analysis is consistent with time-domain statistical evaluation. Finally, the readout system is applied to a quartz pendulum inertial structure, demonstrating its potential for photonic displacement sensing and optical inertial sensor characterization. Full article

Dissolved gas analysis (DGA) is an essential technique for the fault diagnosis and condition monitoring of oil-immersed power transformers. Among various characteristic gases, acetylene (C₂H₂) is a key indicator of high-energy discharge and arc faults. In this work, a high-sensitivity dissolved acetylene detection system is developed based on clamp-type quartz-enhanced photoacoustic spectroscopy (QEPAS). A specially designed clamp-type quartz tuning fork (Clamp-type QTF) is employed as the acoustic transducer to improve acoustic coupling efficiency and optical alignment tolerance. Compared with conventional standard quartz tuning forks, the clamp-type structure exhibits enlarged acoustic interaction volume, lower damping loss, and higher signal collection capability. A near-infrared distributed feedback (DFB) laser operating at 1531.6 nm is used as the excitation source. The dissolved gas is extracted from transformer oil using a headspace degassing module and introduced into the QEPAS cell for real-time measurement. Experimental results showed that the developed system achieves a 1σ-based SNR-estimated detection limit of 17 ppb at a 50 s integration time, derived from the continuous measurement of 0.75 ppm C₂H₂, with excellent linearity in the concentration range from 100 ppm to 500 ppm. The measured concentration of dissolved acetylene in transformer oil is in good agreement with gas chromatography (GC), validating the effectiveness and practical applicability of the proposed system. Full article

We present a whole-rock geochemical dataset of late Variscan intrusive rocks and residual anatectic melts from the mid- and lower continental crust exposed in the Serre Massif of Calabria (southern Italy). A total of 74 samples were collected from the main plutonic units and from leucosomes of associated migmatitic metasediments. The composition of intrusive rocks varies from tonalites and quartz-diorites at deeper structural levels, to peraluminous granites at shallower levels. The dataset includes major, trace and rare earth element (REE) analyses obtained using X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). The dataset integrates new and previously published geochemical data into a consistent and reusable format, including sample locations (WGS84), lithological classification and lithostratigraphic attribution. Sampling sites are also provided as a downloadable geospatial (.kmz) file for visualization in GIS platforms. The data are intended to support a wide range of applications, including studies on granitoid magmatism, water–rock interaction processes in crystalline aquifers and raw materials exploration. Therefore, the dataset represents a valuable resource for both fundamental and applied geoscientific research. Full article

Handheld X-ray fluorescence (HHXRF) scanners generate rapid, low-cost geochemical datasets from core and cuttings, yet their potential for quantitative reservoir characterisation remains largely unrealised, partly because standard multivariate methods are inappropriate for the compositional nature of geochemical data. Here we test, for the first time within a compositional data analysis framework, whether centred log-ratio-transformed HHXRF element compositions can simultaneously predict plug-scale porosity, directional permeability and facies in a siliciclastic reservoir in a continuously cored Brent Group well from the Northern North Sea. The cored interval was logged for facies, sampled for routine core analysis, and analysed by HHXRF at plug sample positions. Sixteen consistently detectable elements were transformed using centred log-ratios to respect the compositional nature of the data, and four Random Forest models were trained: regression models for porosity, horizontal permeability and vertical permeability and a seven-category facies classifier. Models were evaluated using out-of-bag predictions, residual analyses, class-wise reliability metrics and permutation-based variable importance. The models reproduce porosity and permeability with high coefficients of determination (R² > 0.95) and low errors relative to observed ranges and achieve facies classification with substantial agreement (κ = 0.705), with best performance in clean sandstone facies. Predictive skill is dominated by a consistent subset of elements (notably Ca, Ti, Si, V, Zn and Rb), linking bulk composition to mineralogy, depositional texture and diagenetic modification. These results demonstrate that compositional data from HHXRF alone can quantitatively recover key reservoir attributes and facies architecture at plug scale, establishing bulk geochemistry as a robust proxy for reservoir quality in quartz-rich, moderately buried siliciclastic reservoirs. The workflow provides a methodological template for integrating compositional geochemistry with machine learning in subsurface characterisation and, pending multi-well validation, offers a route to cost-effective prediction of porosity, permeability anisotropy and facies from cuttings or high-resolution core scanning. The workflow has direct application to geocellular model population in carbon and hydrogen storage sites, geothermal reservoirs and conventional hydrocarbon fields. Full article

Rapid urbanization has increased the demand for building materials, depleting natural resources used in cement production and prompting the use of alternative and waste materials. This research verifies that eggshell powder waste can fully replace limestone in clinker synthesis. Five clinkers were produced using eggshell powder, aluminum sources (bentonite, zeolite, fly ash, and kaolinitic–illitic clay), Fe-slag, and quartz sand, with mechanical preprocessing (10–30 min) before sintering at 1300 °C. Experimental tests assessed the effects of mix design and mechanical activation on clinkerization, phase formation, temperature, and mechanical properties. XRD, FTIR, and SEM/EDS confirmed consistent phase compositions and primary cement minerals. Aluminum source raw materials contributed significantly to tricalcium aluminate and tetracalcium aluminoferrite formation. Eggshell and fly ash promoted tricalcium silicate and dicalcium silicate synthesis, enhancing cement strength at early and late ages. Longer mechanical pretreatments hindered clinkerization. Eggshell-based cements untreated or pretreated for 10 min are suitable for structural concrete; 20–30 min pretreatment is appropriate for low-demand or non-structural applications. The proposed methodology reduces clinker manufacturing temperature by about 100 °C from the typical range of 1400–1450 °C while maintaining mechanical properties comparable to ordinary Portland cement. Full article

The utilization of locally sourced raw materials for lightweight aggregate (LWA) production has attracted increasing attention due to its potential for cost reduction and sustainable material development. This study investigates the effect of expanded perlite addition (10–40 wt%) on the physical, structural, and mechanical properties of LWAs derived from In Buri red clay, sintered at a relatively low temperature of 800 °C without a conventional high-temperature bloating process. X-ray diffraction (XRD) analysis revealed that quartz remained the dominant phase after sintering, with minor albite and residual illite, indicating limited phase transformation. Thermal analysis showed that major mass loss occurred below 600 °C, confirming that 800 °C is sufficient for removing volatile components. SEM observations demonstrated that increasing perlite content led to the development of a more porous and interconnected microstructure. As the expanded perlite content increased, the bulk density decreased from 1.31 to 0.80 g/cm³, while the apparent porosity and water absorption increased to 48.5% and 60.8%, respectively. Conversely, crushing strength decreased due to increased porosity. These results demonstrate that expanded perlite is an effective additive for tailoring the microstructure and performance of LWAs at low sintering temperature. The developed materials show strong potential for horticultural applications. Full article

Clay minerals in coal play a key role in controlling mineralogical composition, geochemical signatures, and the industrial behavior of coal and its combustion residues. This study investigates the occurrence, provenance, and potential applications of clay minerals in Carboniferous ash-rich coals from the Bogatyr, Lenin, and Saradyr coal mines in northeastern Kazakhstan. A total of 60 coal samples were analyzed using XRD, SEM–EDS/BSE, XRF, and ICP-OES following acid leaching. Based on ash yield, 52 samples were classified as coal (<50% ash), while 8 samples were classified as carbonaceous shale or mudstone (>50% ash). Mineralogical assemblages show clear variability among the studied mines. Saradyr samples are strongly quartz-dominated with lower clay proportions, Bogatyr samples exhibit highly heterogeneous quartz–clay–mica assemblages, whereas Lenin samples are relatively more clay-rich and dominated by kaolinite and illite-group minerals. Across all samples, kaolinite is the dominant clay mineral (16.6–46 wt.%), occurring mainly as authigenic pore- and cell-filling aggregates. Minor phases include illite–muscovite (7.1–29.9 wt.%), illite–smectite (up to 7.6 wt.% in Bogatyr), and smectite–montmorillonite (0.4–0.7 wt.%). Clay minerals occur as discrete particles, coatings, and pore fillings, contributing to ash formation; however, their correlation with ash yield is weak (R = 0.03–0.05), reflecting heterogeneous mineral inputs and diagenetic overprinting. All geochemical data are reported on a high-temperature coal ash (HTA) basis (815 °C). Geochemical indices (CIA, CIW, CIX) and Al₂O₃/TiO₂ ratios (1.8–17.4) indicate variable provenance and moderate to high weathering intensity, reflecting mixed mafic to intermediate source rocks. A total of 23 trace elements were identified. Au occurs at trace levels (up to 0.02 ppm), while selected rare earth elements (REE: Ce, Dy, Eu, La, Nd, Sm, Y, Yb) average 0.2–0.3 ppm, indicating negligible economic recovery potential. REEs show a strong positive correlation with clay minerals (r = 0.93), indicating adsorption and minor structural incorporation. In contrast, Au correlates with As, V, Zn, Cu, Ni, and Nb, suggesting sulfide association. HTA is enriched in SiO₂–Al₂O₃ phases dominated by kaolinite and quartz, indicating strong potential for cement, geopolymer, ceramic, and zeolite applications. Full article

This study investigates the use of mechanical grinding to activate coal bottom ash (CBA) as a low-carbon supplementary cementitious material. Two CBA powders with different fineness levels (75 μm and 45 μm, denoted as SCBA and GCBA) were used to replace 10–50% of cement in mortar specimens. Performance was evaluated through ISO-standard strength tests and the activity index, while micro-analytical techniques characterized the hydration mechanism. The results show that this grinding treatment significantly enhanced pozzolanic activity; at 28 days, the compressive strength of the mixture with 30% GCBA replacement reached 30.6 MPa, which was 44% higher than that of the corresponding SCBA mixture (21.2 MPa). Microstructural analysis confirmed the consumption of portlandite (CH) and the predominant formation of interwoven C-S-H gels and ettringite (AFt), along with residual quartz, calcite, and mullite. These products refine the pore structure and densify the interfacial transition zone. Economic and environmental analysis reveals that CBA substitution reduces raw material costs by 120 CNY/ton and carbon emissions by approximately 261.3 kg CO₂/t. Based on the balance of mechanical integrity and environmental benefits, mechanical grinding of CBA to 45 μm at a 30% cement replacement level is proposed as a promising approach for producing low-carbon cementitious materials and for future application in green concrete. Full article

Quartz crystal microbalance (QCM) technology provides a powerful, label-free platform for monitoring molecular interactions in real time with nanogram sensitivity. Recent advances in compact instrumentation have enhanced analytical performance while reducing energy consumption, aligning with the principles of Green Analytical Chemistry. In parallel, the European Union has recommended the replacement of animal-derived antibodies with non-animal alternatives, creating an urgent need for sustainable affinity receptors. In this study, we present an innovative application of polynorepinephrine (PNE)-based molecularly imprinted polymers (MIPs) with a compact QCM sensing. PNE, a bioinspired polymer formed under mild aqueous conditions, offers strong adhesive properties and biocompatibility, enabling robust immobilization of imprinted receptors on gold-coated quartz disks. The resulting PNE-MIP/QCM platform combines the ultrasensitivity of quartz microbalances with the selectivity of molecular imprinting, delivering a reproducible and environmentally responsible affinity sensor. The sensor showed a limit of detection of 11.2 nM and enabled accurate IgG quantification in diluted human serum samples. As a proof of concept, the system was applied to Human Immunoglobulin G (IgG1) detection, demonstrating its potential for sustainable clinical diagnostics. Full article

Quartzites containing malachite–azurite mineralization identified in the Kırşehir region (Central Anatolia, Türkiye) are located within the Kırşehir Massif. This study aims to comprehensively characterize the mineralogical, petrographic, geochemical, and gemological properties of these quartzites and to evaluate their potential as ornamental and decorative stones. Due to their characteristic green and blue colors, malachite and azurite possess significant aesthetic value. Their occurrence within silica-rich and mechanically resistant quartzites enhances the visual appearance of the host rock while maintaining its structural integrity. Petrographic observations indicate that the quartzites exhibit a granoblastic texture composed of interlocking quartz crystals. Malachite–azurite mineralization is structurally controlled by NW–SE-trending fracture systems and occurs predominantly as fracture-filling and cavity-coating phases, indicating an epigenetic origin related to post-metamorphic fluid circulation. Geochemical analyses reveal that the samples are dominated by SiO₂ (~95.33 wt.%), with CuO (~1.77 wt.%) and elevated Cu contents (3205 ppm) confirming the presence of copper carbonate mineralization. Although the high silica content contributes to overall mechanical strength, the relatively low Mohs hardness (3–4) and chemical sensitivity of malachite and azurite represent important limitations. Quantitative gemological measurements further indicate that quartz-rich domains exhibit high hardness values (up to ~907 HL), whereas malachite–azurite-bearing zones display significantly lower hardness (~735 HL) due to fracture-controlled heterogeneity and the presence of softer carbonate phases. Surface brightness measurements show moderate to high gloss values (~73–80 GU), with noticeable improvement following epoxy impregnation. These results demonstrate that while the material exhibits favorable optical properties, its mechanical performance is strongly influenced by mineralogical contrasts and structural discontinuities. Quartzites bearing malachite–azurite mineralization are therefore suitable primarily for decorative stones, ornamental objects, and small-scale jewelry applications rather than high-quality gemstones. The striking color contrast between azurite, malachite, and quartz enhances their visual appeal, and with appropriate stabilization techniques, their durability and economic value can be partially improved. Full article

Mercury ion, a highly toxic and bioaccumulative heavy metal pollutant, poses significant risks to human health and ecosystems even at trace concentrations. Therefore, the development of highly sensitive and selective analytical methods for mercury ions is critically important to safeguard environmental integrity and human health. In this work, 4-mercaptopyridine-functionalized gold nanoparticles (4-MPY-AuNPs) were synthesized and subsequently immobilized onto quartz slides to fabricate a localized surface plasmon resonance (LSPR) sensor. Exploiting the selective coordination interaction between the pyridyl nitrogen atoms of 4-MPY and Hg²⁺, this LSPR sensor enables highly specific detection of Hg²⁺. Moreover, injecting a trace amount of 4-mercaptopyridine-functionalized AuNPs into the flow cell triggers the in situ formation of a surface-confined AuNP–Hg²⁺–AuNP sandwich architecture, thereby enhancing the sensor’s sensitivity. Under the optimized conditions, the proposed method exhibited a linear dynamic range of 1 × 10⁻⁹–6 × 10⁻⁷ mol L⁻¹, with a correlation coefficient (R²) of 0.9917 and a limit of detection (LOD) of 3.2 × 10⁻¹⁰ mol L⁻¹; the LOD of this method is one order of magnitude lower than the LODs reported in contemporary Hg²⁺ detection methods. This method exhibits high selectivity, sensitivity, cost-effectiveness, and is label-free, thereby demonstrating significant potential for environmental applications. Full article

The rapid and precise detection of biomarkers and pathogens remains a critical challenge in clinical diagnostics. Traditional methodologies are frequently hindered by protracted workflows, complex sample preparation, and reliance on resource-intensive instrumentation. Acoustofluidics—the synergistic integration of acoustics and microfluidics—has emerged as a transformative solution for point-of-care testing (POCT). Bulk acoustic wave (BAW) and surface acoustic wave (SAW) technologies enable the contactless, label-free, and biocompatible manipulation of bioparticles across micro- and nanometer scales. This review critically examines recent advancements in BAW- and SAW-based acoustofluidic biosensors. We elucidate the fundamental principles governing distinct acoustic modes—including Quartz Crystal Microbalance (QCM), film bulk acoustic resonator (FBAR), and Solidly Mounted Resonator (SMR) for BAW and Rayleigh and Love waves for SAW—and evaluate their specific roles in liquid-phase sensing, particle sorting, and cellular focusing. Results show that integrating on-chip sample preparation accelerates diagnostic workflows, reducing assay times to under 10 min. Coupling acoustic manipulation with optical, mass-based, or electrochemical modalities effectively overcomes fundamental diffusion limits, achieving ultrasensitive, multimodal detection. We address translational challenges—acoustothermal heating, biofouling, and scalable integration. Following a discussion of clinical applications in oncology and infectious diseases, we map emerging trajectories, emphasizing AI-driven intelligent microfluidics, modular architectures, and flexible wearable platforms that will ultimately democratize continuous precision diagnostics. Full article

Fourier Transform Infrared Spectroscopy (FTIR) is increasingly used for the mineralogical characterization of complex materials such as ceramics, soils and clays. However, its quantitative application remains limited due to spectral overlapping and matrix effects in solid samples. In this study, a semi-quantitative mineralogical analysis method based on Attenuated Total Reflectance FTIR (ATR-FTIR) is proposed. The method uses the principal absorption band of calcite as a normalization reference in order to estimate relative molar absorptivity coefficients according to the Lambert–Beer law. Experimental spectra obtained from pure minerals and laboratory mineral mixtures were analyzed using derivative spectroscopy and numerical optimization. The correlation between experimental and calculated spectra was performed using the GAMS equation modeling environment and the nonlinear programming solver CONOPT. Mineral mixtures were used to determine the minimum detectable band intensity and detection limits. Bands with normalized intensities lower than 0.01 were discarded, corresponding to a detection limit of approximately 7 mol%. Application of the proposed methodology to ceramic coatings samples from Teruel and Castellón demonstrated that the FTIR spectra are dominated by aluminosilicate bands associated with quartz and clay minerals, together with carbonate features attributable to calcite. These results are consistent with the expected mineralogical composition of ceramic raw materials and confirm the suitability of the method for analyzing natural samples. However, the ATR-FTIR method presents several inherent limitations that may affect both the accuracy and reproducibility of spectral data. Full article

Oil–water emulsions constitute essential components in a wide range of industries. Despite their extensive use in emulsion systems, synthetic emulsifiers are often associated with environmental concerns and high costs. In this study, lignin—a by-product of the pulping industry—was polymerized with acrylic acid and employed as an emulsifier in a xylene–water system to address this challenge. When testing two lignin–acrylic acid copolymers, the results confirmed that the one possessing a higher molecular weight (7.99 × 10⁵ g/mol) and charge density (4.7 mmol/g) (KL-AA-10) generated xylene–water emulsions with improved stability, and higher viscosity and viscoelastic moduli. These observations were consistent with the greater adsorption of this polymer, relative to the counterparts with a lower molecular weight and charge density at the xylene–water interface, as monitored using a Quartz Crystal Microbalance. The adsorption of KL-AA-10 resulted in the formation of smaller emulsion droplets (D50 = 0.6 µm) within the system, as evidenced by confocal microscopy analysis. This study underscores the potential of lignin as a renewable emulsifier for diverse applications. Full article