Search Results (967)

Gallium is a critical metal for high-tech industries, with its global demand surging in recent years. Currently, approximately 90% of primary gallium is extracted from Bayer liquor. Chelating resins such as amidoxime sorbents are widely adopted commercial materials for this purpose. However, gallium recovery from such highly caustic media remains a formidable challenge, as gallium is present at low concentrations while aluminate ions are hundreds of times more abundant, and the medium is rich in competing vanadate ions and humic substances. These interfering components impede both adsorption and desorption cycles, leading to a progressive decline in resin performance and a subsequent increase in operational costs. In recent years, functionalized carbon-based materials have gained significant traction. This growing interest is motivated by the carbon-based materials’ exceptional chemical resilience across both acidic and alkaline environments, tunable surface chemistry, and facile re-functionalization. This mini-review synthesizes recent progress in functionalized carbon-based materials for gallium recovery, with a particular emphasis on their adsorption performance and mechanistic insights. At the end of the paper, major challenges and research gaps are identified, and future research directions are proposed. Full article

Visible–near-infrared (VNIR) hyperspectral imaging is promoted as a rapid substitute for ICP-MS in soil heavy metal monitoring, yet most evidence rests on single-split or non-nested validation. This study benchmarks VNIR prediction for Camellia oleifera plantation soils in Changshan County, Zhejiang, China (n = 83; 102 bands, approximately 401–1022 nm; 51 modeling indicators) under strict nested cross-validation, with all imputation, scaling, preprocessing, and model selection confined to each outer training fold. Four findings emerged. First, the highest observed mean ratio of performance to deviation (RPD) under the present protocol was 1.13. This did not reach the empirical 1.4 interpretive benchmark adopted here, and most fold-wise R² values were negative. Second, a 1D-CNN with squeeze-and-excitation attention performed significantly worse than a linear baseline for six of ten indicators and better for none; gains seen in the earlier non-nested exploratory analysis did not persist under leakage-controlled evaluation. Third, re-casting the task as regulatory risk level classification did not recover operational utility: Cr and Zn recall values were supported by only two and one exceeding samples, respectively, and cannot estimate population screening sensitivity. Fourth, an exploratory post hoc SHAP analysis using a full-data Random Forest assigned 24% of top wavelengths to Fe-oxide or organic-matter reference bands versus a 5.9% permutation null mean (empirical p = 0.020, the minimum attainable with 50 permutations). This attribution identifies plausible spectral proxy regions but is not independent evidence of predictive generalizability or causality. Separately, 22.9% of plots exceeded the GB 15618-2018 arsenic risk screening value. Within this dataset and validation design, VNIR imaging therefore supports neither reliable quantitative prediction nor operational screening. Full article

Although the mineralogical form of occurrence of critical metals is widely recognised as a key factor controlling their recovery during beneficiation, this relationship has rarely been verified directly on freshly mined ore and its primary beneficiation products from Central Asian polymetallic deposits. This raises the research question of how the mineralogical mode of occurrence of Bi, In, Cd, Co, Se, Te and Re governs their distribution between gravity and flotation products. Accordingly, the aim of this study was to establish how the mineralogical form of occurrence of these critical metals determines their distribution among gravity-concentration and flotation products, using ores from the Zhuantobe and Strezhanskoe deposits (Kazakhstan) as a case study. To this end, the mineralogical features and distribution patterns of critical metals during gravity and flotation beneficiation of polymetallic ores from these deposits were investigated by optical microscopy, X-ray diffraction, and SEM-EDS, while metal distribution among beneficiation products was determined by chemical analysis. Sphalerite, galena, pyrrhotite, and silver tellurides were identified as the main carriers of the critical metals, with bismuth occurring as an isomorphic admixture in sphalerite (3.69 wt.%) and galena (1.85 wt.%). During flotation, distribution was governed by mineralogical affinity: cadmium and indium were preferentially concentrated in the zinc concentrate (56.31% and 15.44% recovery, respectively), bismuth in the copper–lead concentrate (23.03%), and selenium and rhenium in the copper-bearing products (23.60% and 37.05%). Correlation analysis of the gravity-concentration products confirmed a close association of cadmium with sphalerite (R² = 0.9998), bismuth with galena and sphalerite (R² = 0.9674), and cobalt with iron-bearing sulfides (R² = 0.9144). These results demonstrate that the distribution of critical metals is governed primarily by their mineralogical form of occurrence rather than by bulk ore content, providing a basis for technologies for the complex processing of polymetallic ores. Full article

Firmware forms the persistent software layer controlling embedded and Internet-of-Things (IoT) devices, industrial controllers, automotive systems, and cyber-physical infrastructure. Vulnerabilities in firmware enable remote compromise, supply-chain attacks, and long-lived implants that survive operating-system reinstallation. This review synthesises 118 works published from 2014 to 2026—comprising 78 primary research studies; 23 surveys and systematisations of knowledge; and 17 benchmarks, tools, and background references—covering the full firmware reverse engineering (FRE) pipeline: physical acquisition (including fault injection and side-channel extraction), format analysis and unpacking, static analysis (binary code similarity detection, protocol reverse engineering, and patch diffing), dynamic analysis and hardware emulation, fuzzing-based vulnerability discovery, and artificial intelligence (AI) and large language model (LLM)-assisted analysis. Three additional dimensions are surveyed: digital twin-assisted firmware security testing; secure boot, trusted execution environment (TEE), and over-the-air (OTA) update security; and firmware rootkit and implant detection. Coverage spans two axes—the firmware class (Linux-based IoT, microcontroller-unit bare-metal, RTOS, UEFI/BIOS, PLC/ICS, and automotive ECU) and analysis depth (surface scanning to exploit-validated vulnerability chains). We identify ten structural gaps, including the absence of unified evaluation benchmarks, fragmented peripheral modelling, the scalability–fidelity trade-off in re-hosting, and insufficient grounding of LLM tools in firmware-specific realities. We conclude with six research directions for trustworthy, scalable, and infrastructure-aware firmware analysis. Full article

The development of simulated-solar-light photocatalysts for methyl orange (MO) removal is limited by insufficient light utilization, rapid photogenerated charge recombination, and restricted interfacial reaction sites. Here, vertically aligned ZnO nanorods on a conductive nanoporous Cu (NPCu) scaffold were modified with low-abundance RE-containing surface species (RE = Ce, Sm, Er, Tm, and Yb). The notation RE(OH)₃@ZnO/NPCu is retained solely as an operational sample identifier and does not constitute a crystallographic or stoichiometric phase assignment. XRD resolves the ZnO/NPCu framework, EDS confirms the local presence of RE, and XPS identifies RE-dependent oxidation state and surface oxygen environments; collectively, these measurements do not uniquely establish RE(OH)₃ or distinguish hydroxide from oxide, oxyhydroxide, and other hydroxylated/adsorbed surface configurations. The distinguishing feature is a controlled five-RE comparison on one common ZnO/NPCu architecture, together with separate evaluation of NPCu under H₂O₂-free and H₂O₂-assisted conditions. Across three independent H₂O₂-free runs, the Er-modified sample achieved 96.61 ± 0.30% MO degradation within 9 min with k_obs = 0.3930 ± 0.0071 min⁻¹. Dosage screening identified 20 μL of 40 wt% H₂O₂ in 20 mL MO solution (approximately 13.5 mM) as a practical plateau dosage. Photolysis, dark, NPCu/H₂O₂, and catalyst-removal controls support an additional solid-catalyst-dependent Cu-associated peroxide contribution while not excluding trace homogeneous reactions. Three independent cycling experiments and post-cycle SEM/XRD/EDS support operational durability, although quantitative metal leaching was not measured. Tauc, Mott–Schottky, EIS, temperature-dependent kinetic, and scavenger results are interpreted as comparative descriptors or indirect evidence rather than direct proof of intrinsic band gaps, atom-specific carrier densities, or a unique microscopic mechanism. The AI-assisted component is restricted to exploratory contextualization because reference-grouped validation shows poor out-of-reference generalization. The conclusions are confined to the tested MO system. Full article

Landfill leachate circuits that operate without discharge, by recirculating aerated leachate onto the waste mass, are widespread in South-East Europe, yet their long-term behaviour is rarely documented with sample-level data. This study reports a six-year (2020–2025) seasonal monitoring campaign at a sanitary landfill in northern Serbia (alluvial aquifer of the Sava River, transboundary Danube basin) and re-examines it with a transparent multivariate protocol. Seventy-two leachate samples (collection well, aeration lagoon, sedimentation lagoon; n = 24 each, 30 parameters), 28 realised surface-water campaigns, and six years of groundwater summaries were evaluated by principal component analysis/factor analysis (PCA/FA, Varimax normalized), hierarchical cluster analysis, PERMANOVA, non-parametric paired tests and, for benchmarking, supervised machine learning. The pooled leachate model (n = 72; 21 variables; KMO = 0.700; Bartlett χ² = 956, p < 0.001) retained four factors by parallel analysis, explaining 61.6% of total variance; after rotation the factors accounted for 27.7%, 14.3%, 10.4%, and 9.3%. Factor 1 grouped organic load with particle-reactive metals (COD, BOD₅, Fe, Ni, Cr, As, Zn), Factor 2 a reduced sulfur–fluoride–BTEX signature, Factor 3 temperature-driven nitritation, and Factor 4 a nitrate–manganese redox contrast. Crucially, paired campaign-by-campaign comparison showed no removal of the dominant pollutants along the circuit. Median COD, BOD₅ and NH₄-N were not lower in the sedimentation lagoon than in the collection well, while pH rose from 8.08 to 8.75 (p < 0.001); only Cu, Pb, NO₃-N, and NO₂-N decreased significantly. The circuit therefore homogenises and concentrates dissolved load rather than removing it. Downstream surface water was significantly enriched in electrical conductivity (+110 µS/cm), total dissolved solids, NH₄-N, and NO₂-N relative to upstream (Wilcoxon, p < 0.05), and groundwater showed episodic conductivity up to 12,760 µS/cm and NH₄-N up to 102 mg/L. Cytotoxicity (MTT) confirmed biological relevance, with MRC-5 viability falling to 37% after 24 h exposure to 50 vol.% groundwater (Pw3) versus 60% in A549 cells. A random-forest classifier separated circuit units far better than PCA-based discrimination (76.4% versus 54.2% cross-validated accuracy) and distinguished the 2020–2021 pandemic period from 2022–2025 with 94.2% accuracy, a period effect also confirmed by PERMANOVA (R² = 7.2%, p < 0.001). The results indicate that closed-loop recirculation without an engineered discharge barrier transfers, rather than eliminates, contaminant load, and that after-care of such systems requires mass-balance monitoring and polishing treatment. Full article

One-pot protocols leading to target products in two or more sequential reactions, without the separation and isolation of intermediate products, are powerful synthetic tools. In fact, they surpass usual procedures based on single-step reactions in terms of efficiency, cost, and green aspects. The appeal of such methodologies is further increased with the use of catalysts, which makes the process easier and more efficient, minimizing unwanted byproducts. In this context, this paper describes three new one-pot protocols, based on an oxo-Re(V)-catalyzed Meyer–Schuster rearrangement of different secondary propargylic alcohols to the corresponding α,β-unsaturated ketones. These products, without isolation, subsequently, can undergo the 1,4-conjugate addition of a soft Gilman copper nucleophile or the intramolecular cyclocondensation with hydrazine hydrochloride to pyrazoles. Moreover, the ketone formed by the addition of a Gilman reagent can further be reduced in situ with LiAlH₄ to the corresponding secondary alcohol. The remarkable aspects of these novel procedures involving two and three one-pot consecutive steps are the high overall yields, the readily available reaction conditions, and the compatible presence of two transition metallic species in the same reaction medium. Full article

Nanomedicine has advanced cancer theranostics via targeted delivery and phototherapy, yet many high-performance systems rely on inorganic or metal-intensive materials synthesized through energy-demanding routes, raising concerns about biocompatibility, environmental accumulation, and sustainability. This review re-evaluates polypyrrole (PPy)-based nanomedicines from a green chemistry perspective, shifting focus from performance-centric optimization to sustainability-guided design. PPy, an organic conductive polymer with near-infrared photothermal activity and structural tunability, offers a promising platform. However, pristine PPy suffers from limited functionality, poor biodegradability, and insufficient reactive oxygen species (ROS) generation. Reported FeCl₃-, CuCl₂-, and Fe²⁺/H₂O₂-mediated routes are compared to examine formulation-specific relationships among synthesis conditions, polymer characteristics, redox behavior, ROS-related function, and process burdens. Because the underlying studies differ in composition, processing, purification, and assay conditions, these comparisons are used to identify evidence-supported trade-offs and data gaps rather than to establish a universal causal hierarchy. Green strategies are critically assessed, including one-step carboxylated copolymerization for backbone degradability and metal–polyphenol networks for catalytic ROS amplification. To organize the heterogeneous evidence, this review introduces a PPy-specific dual-axis evidence map that considers process-related sustainability alongside biofunctional performance. This qualitative tool is intended to identify trade-offs and evidence gaps rather than provide a validated sustainability score. Full article

Metal foams and nanofluids are recognized as attractive and effective heat transfer enhancement methods. This study numerically investigates forced convection heat transfer and second-law thermodynamic behavior of water and a 0.02% Cu–MXene/water hybrid nanofluid flowing through a tube partially filled with metal foam. Three configurations are examined: a clear tube as the reference case; Case A (three discrete foam blocks occupying 3/16 of the tube length); and Case B (a single block occupying 9/16), using four metal-foam types (aluminum 30/45 PPI, copper 40 PPI, and nickel 60 PPI). The governing equations are solved using the finite-volume method with the SIMPLER algorithm and validated against published experimental and numerical data. Results show that Case B provides higher heat-transfer rates and performance evaluation criterion (PEC) values than Case A, although at the expense of larger pressure-drop and pumping-power penalties. The highest heat-transfer enhancement is obtained with Cu-40 PPI foam and the hybrid nanofluid in Case B, where the average Nusselt number increases by a factor of 3.33 at a Reynolds number of Re = 200 relative to water in the clear tube. Higher-thermal-conductivity foams, combined with the hybrid nanofluid, provide greater thermohydraulic benefits than lower-conductivity foams with water. The second-law analysis reveals that increasing Re reduces thermal irreversibility but increases frictional irreversibility, highlighting the competing effects of heat-transfer enhancement and hydraulic resistance. Overall, the Cu-40 PPI/hybrid nanofluid combination in Case B at low Re provides the most favorable performance among the investigated conditions. Full article

Over the past two decades, the world has experienced a significant and relentless increase in environmental degradation, measured through carbon emissions (CO₂). These emissions have been one of the persistent global concerns. South Africa boosts abundance of natural resources and some of the world’s most substantial mineral deposits, endowments in the form of precious metals, diamonds and gold. The paper aims to examine the impact of socio-economic and energy-related factors on environmental degradation from a South African perspective. Using multivariate annual data spanning from 1991 to 2022, the Autoregressive Distributed Lag Model (ARDL) was employed to determine both short-run and long-run impact of financial development (FD), renewable energy (RE), non-renewable energy (NRE), unemployment rate (UNE), economic growth (GDPPC), and population growth (PoPG) on CO₂ emission. The results show that NRE remains a dominant driver for environmental degradation, while RE is positively associated with emissions under current system conditions. FD exhibits short-run emission-intensity but long-run mitigation effects. The results suggest a need for relevant policymakers to prioritize coal displacement, stimulate economic growth and promote access to green financing, and related technologies and consumption, to enhance and promote environmental quality in South Africa. The conclusion is that South Africa’s energy-economy nexus is still at a transitional stage, where targeted policy intervention and structural reform are essential to accelerate the shift towards a low-emission economy. Future research can extend the analytical depth by exploring asymmetries, disaggregating fossil fuels, and incorporating broader environmental indicators. Full article

The geometric morphology and dynamic evolution of the molten pool are key indicators of heat input, metal transfer, and solidification behavior during welding, making them critical for quality monitoring and process control. To address the challenges of molten pool image segmentation under complex conditions, including strong arc interference, blurred boundaries, small foreground regions, and significant shape variations, a MIG welding-based visual acquisition system is established to construct a multi-condition dataset. Based on this dataset, an efficient boundary-guided dual-branch network, WPSeg-Net, is proposed. The network employs ResNet-34 as the encoder, integrates a lightweight Transformer module for global context modeling, and adopts BiFPN for multi-scale feature fusion. A region branch and a boundary branch with a mutual guidance mechanism are further designed to improve segmentation accuracy and boundary refinement. Experimental results demonstrate that WPSeg-Net achieves an IoU of 92.83% and a Dice score of 96.28%, improving by 0.98% and 0.58% over DeepLabV3+, respectively. Meanwhile, the proposed method reduces the parameter size from 22.43 MB to 21.78 MB and decreases FLOPs from 62.25 G to 31.90 G, achieving a better balance between segmentation performance and computational efficiency. Full article

The electrochemical regeneration of sodium borohydride (NaBH₄) from spent metaborate is a central bottleneck for circular hydrogen storage. (1) Background: The eight-electron reduction of the aqueous borate species B(OH)₄⁻ to BH₄⁻ is thermodynamically out-competed by the hydrogen-evolution reaction (HER) by about 0.41 V at every pH, so selectivity can only be won kinetically. (2) Methods: We advance an ambiphilic-site hypothesis, screen 30 candidate metal centres using entirely experimental, tabulated descriptors (bulk HER exchange current density; gas-phase M-O bond energy) with no new electronic-structure computation, and then audit the transferability of both descriptor axes against published, corrected DFT datasets for nitrogen-coordinated single-atom sites. (3) Results: At the parent-metal level, the two axes are orthogonal (Spearman ρ = 0.02) and the score passes a family-level experimental validation over seven bulk-electrode metals (ρ = 0.69; exact permutation p = 0.050), separating the HER-dominated noble-metal family from the single-atom Mn benchmark. The site-level audit shows that the oxophilicity axis transfers to M-N₄ sites almost quantitatively (ρ = −0.84 pyridine-4N, −0.95 pyrrole-4N, n = 23) while the bulk HER axis does not, and that site-level scaling between oxygen and hydrogen binding narrows the productive window to oxophilic centres that over-bind hydrogen. (4) Conclusions: The site-anchored screen redirects the search from the parent-metal leaders (La, Ce, Y, Ti, Sc) to refractory single-atom centres, with W, Nb and Mo as priority synthesis targets (Re excluded on scarcity; Zr, Hf, Ta as data-supported extensions; Ti as the sustainability-anchored borderline case) and the lanthanides retained only as explicitly extrapolative candidates. All data and analysis code are openly deposited. Full article

Acute and chronic wounds remain a major clinical burden, motivating the design of multilayer biomedical composite systems capable of combining structural support, antimicrobial protection, and controlled release of therapeutic agents within a single device. These architectures integrate natural and synthetic biomaterials, hydrogels, electrospun membranes, bioactive nanoparticles, and 3D-printed scaffolds to reproduce the multifunctionality of the native extracellular matrix. This review examines how layer-by-layer design and biomaterial selection govern mechanical strength, as well as bioactivity, and how these parameters can be tuned to the distinct phases of wound repair. Particular emphasis is placed on strategies for incorporating growth factors, antimicrobial agents, metal/metal-oxide nanoparticles to enhance re-epithelialization, angiogenesis, and infection control; emerging gene-based delivery strategies are also discussed. The main technologies and biomaterial combinations reported to date are compared, alongside a critical overview of their in vitro and in vivo performance. Reproducibility, scalability, and regulatory standardization remain the main barriers to clinical translation. We conclude by outlining priority research directions to advance multilayer composites from bench-scale prototypes toward approved wound-care products. Full article

Deploying object detection models on low-power embedded devices requires a careful balance between detection accuracy, runtime performance, and energy efficiency, especially for aerial images that contain small objects. We present a hardware-measured evaluation of Edge-TPU-compatible detectors on an MCU-class NXP i.MX RT1176 (bare-metal FreeRTOS, Cortex-M7) driving a Coral Edge TPU over an internal USB 2.0 link. We benchmark quantized YOLOv5-based detectors at input resolutions from 256 to 1024 px, reporting the accuracy (size-stratified AP_S on the VisDrone person split) together with the measured per-frame and per-pixel energy, sampled at 100 Hz with an automatic window and N ≥ 5 repetitions. We use the energy per pixel as a resolution-normalized view, not as a new metric, to show where the analytical model fails. The measured per-pixel energy departs from the compute (MAC)-based model because the inference is transfer-bound: it is dominated by the instruction stream and input activations re-sent over USB on every invoke, while the parameters stay cached on-chip. An Edge TPU clock sweep and a compiler-byte analysis agree independently that about 79% of each invocation is the USB transfer. This gives concrete design rules (a lower clock is more energy-efficient; ReLU is preferred to SiLU), and shows that the USB 2.0 ceiling is architecturally fundamental for the MCU class. Full article

Reversible solid oxide cells (ReSOCs) represent one of the most promising electrochemical technologies for sustainable energy conversion and storage, yet their large-scale deployment remains constrained by electrode materials capable of sustaining stable performance under alternating oxidizing and reducing conditions. Reversible solid oxide cells require electrode materials that combine phase stability, chemical compatibility, redox tolerance and a microstructure suitable for gas transport and surface reactions. However, the relationships among cation composition, thermal processing, phase formation and local chemical homogeneity remain insufficiently understood, particularly for compositionally complex perovskite-related oxides. In this work, this problem was addressed through a comparative physicochemical screening of three candidate electrode materials synthesized by a simple co-precipitation route: two co-doped lanthanum ferrites, (La_0.8Sr_1.2) (Fe_0.9Co_0.1)O_6+δ (LSFC) and (La_0.8Ca_1.2) (Fe_0.9Co_0.1)O_6+δ (LCFC), and one high-entropy praseodymium nickelate, Pr(Ba_0.8Ca_0.2)(Fe_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2)₂O_6+δ (PBC-HEO). DTA–TG analysis was used to determine the thermal decomposition and crystallization ranges of the precipitated precursors. Phase evolution as a function of calcination temperature was investigated by X-ray diffraction, while Raman and FTIR spectroscopy were employed to examine the local metal–oxygen environment and structural disorder. Raman spectroscopy confirmed the formation of perovskite-type metal–oxygen frameworks in all samples and revealed distinct redistributions of spectral weight between apical/equatorial (or symmetry-related) BO₆ stretching sub-modes and bending/tilting modes, reflecting different local defect-chemical mechanisms associated with A-site doping (Sr vs. Ca) in the Ruddlesden–Popper ferrites and B-site multi-cation occupancy in the double-perovskite PBC-HEO. Bulk and local elemental compositions were assessed by ICP-MS and SEM-EDS, respectively, and SEM was used to compare particle morphology and porosity. SEM-EDS analysis showed that PBC-HEO developed the most open and interconnected microstructure among the investigated powders, although accompanied by residual compositional heterogeneity. This morphology may favor gas accessibility; however, its effective impact on electrocatalytic performance requires dedicated surface area, porosimetry, electrical, and electrochemical measurements. LSFC formed a single major Ruddlesden–Popper phase only after high-temperature calcination, whereas LCFC retained calcium-containing secondary phases. PBC-HEO developed a major perovskite-related phase at 700 °C, accompanied by minor Zn-rich segregation. Under the selected processing conditions, PBC-HEO retained the finest and most interconnected porous microstructure, although it also displayed the highest local compositional heterogeneity. These results demonstrate that cation selection and thermal history jointly control phase stability, local disorder and microstructure, providing a basis for the subsequent electrochemical evaluation and optimization of perovskite-related ReSOC electrode materials. Full article