Search Results (858)

The Xianglin Sn polymetallic deposit, located on the northwestern margin of the Cuonadong dome in the eastern Tethyan Himalaya, represents an important Sn-W-Be polymetallic system recently recognized in southern Tibet. This study investigates the nature and evolution of the ore-forming fluids and the mechanisms of cassiterite precipitation. Fluid inclusion petrography, microthermometry, and laser Raman spectroscopy were applied to inclusions from the cassiterite–sulfide, proximal cassiterite–quartz vein, distal cassiterite–quartz vein, and late fluorite–quartz vein stages. The fluid inclusions mainly comprise liquid-rich, vapor-rich, H₂O-CO₂ three-phase, and minor daughter-mineral-bearing inclusions. The cassiterite–sulfide stage contains the most complex inclusion assemblage, with homogenization temperatures of 326–399 °C and salinities of 2.4–10.5 wt.% NaCl equiv. The proximal cassiterite–quartz vein stage yields homogenization temperatures of 280–361 °C and salinities of 2.4–9.6 wt.% NaCl equiv., whereas the distal cassiterite–quartz vein stage records lower temperatures of 195–295 °C. The fluorite–quartz vein stage is characterized by low-temperature and low-salinity fluids. Raman spectra identify CO₂, N₂, CH₄, H₂S, and CaCO₃ daughter minerals, indicating a volatile-rich, relatively reduced H₂O-CO₂-NaCl hydrothermal system. These features suggest that the principal ore-forming fluids were dominantly magmatic–hydrothermal fluids exsolved from highly fractionated Miocene leucogranites. During upward and outward migration from the main detachment zone to peripheral fractures, the fluids experienced boiling, cooling, mixing, and multistage hydrothermal overprinting. Cassiterite precipitation during the cassiterite–sulfide stage was mainly triggered by boiling or phase separation, whereas the proximal cassiterite–quartz veins were controlled by progressive cooling and local phase separation. In contrast, distal cassiterite precipitation was more strongly influenced by fluid mixing and cooling. These results indicate that the Xianglin deposit records a structurally controlled proximal-to-distal magmatic–hydrothermal Sn mineralizing system related to the Cuonadong dome. Full article

To probe a possibility of symmetry breaking within chainlike σ-conjugated polymers, we investigated the preservation of P-odd/T-even and P-odd/T-odd symmetries in semiflexible poly(n-butyl-isobutylsilane) (C4-iBS), which lacks point chirality. Using circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy in various achiral solvents, we recorded three sets of temperature-dependent CD generation and inversion at the Siσ–Siσ* transitions, which were assigned to 11₄-, 8₃-, and 7₃-helices, respectively. In n-hexadecane-h₃₄, C4-iBS exhibited a CD inversion due to an 8₃-helix reversal from g_abs = −1.3 × 10⁻³ (40 °C) to +0.7 × 10⁻³ (20 °C). The observed H/D isotope effects in n-hexadecane-h₃₄ and -d₃₄ suggest that ¹H and ²H nuclei contribute differently to the temperature-dependent 8₃-helicity. Remarkably, photoexcited C4-iBS at 20 °C displayed dynamic CPL oscillations at 330 nm, alternating between g_lum = −7 × 10⁻² and +9 × 10⁻² at ~20 s intervals. These CD and CPL results suggest a mixing of P-odd and P-even states in both S₀- and S₁-states. Furthermore, magnetic circular dichroism (MCD) and magnetochiral dichroism (MChD) under a reversing H₀ = ±0.45 T at 23 °C produced non-mirror-image MCD/MChD spectra and their non-identical unpolarized MUV/MChUV spectra. These observations and analysis imply the simultaneous mixing of P-odd/P-even and T-odd/T-even terms in the S₀- and S₁-states of C4-iBS. Full article

This study aimed to evaluate the micro-shear bond strength (μSBS) of TheraCal PT (TP), Endocem MTA Premixed Heavy (EC), One-Fil Putty (OF), and BC Universal RRM (RM) bonded to a flowable composite resin using two universal adhesives (G-Premio Bond or Prime & Bond Universal) in two etching modes (etch-and-rinse or self-etch). Disc-shaped specimens (n = 60 per pulp capping material) were allowed to set for 72 h and then divided into four groups according to the adhesive and etching mode used. The μSBS was measured using a universal testing machine. Data were analyzed with three-way ANOVA and post hoc tests for the pulp capping material. Failure modes were determined. Spectra were recorded before and after adhesive application using attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy. Three-way ANOVA revealed that the effects of the adhesive (p = 0.002), etching mode (p < 0.001), and pulp capping material (p < 0.001) on the μSBS were significant. The interaction between the adhesive and etching mode, as well as the interaction between the adhesive and pulp capping material, was significant (p < 0.001). TP exhibited higher μSBS values than EC, OF, and RM. TP failed in mixed, cohesive, and adhesive modes, whereas EC, OF, and RM failed mostly cohesively within the material. ATR-FTIR spectroscopy confirmed the functional monomer peaks on the material surfaces after adhesive application. Full article

During the study of premixed NH₃/CH₄ fuel mixtures, flame separation into two reaction zones was observed upon flashback into a Bunsen burner. Stable combustion regimes were obtained, with a gap between the burner rim and the upper luminous region, the size of which depended on the mixture composition and the position of the combustion zone inside the burner. The work examines combustion regimes of NH₃/CH₄ mixtures with an ammonia content of 10–60% in the fuel blend. The equivalence ratio was varied in the range of 0.95–1.1. The Reynolds number was maintained in the range of 270–300, ensuring laminar flow conditions. At the burner exit, temperature and gas composition profiles were measured. Flame emission was recorded at the chemiluminescence bands of OH* (308 nm) and CH* (431 nm), and emission spectra were acquired both inside and outside the burner. Spectra in the range of 190–1080 nm were recorded. Spectral analysis revealed a band corresponding to NO₂ emission in the upper part of the luminous region. It is most likely that nitrogen dioxide is formed through low-temperature reactions occurring when the combustion products mix with atmospheric air. Full article

We formulate a gauge-invariant phenomenological theory for a charged three-component condensate in an anisotropic layered superconductor. The construction is conditional on a material-specific pairing calculation selecting an isolated, predominantly triplet channel; it does not infer triplet pairing from layering or spin–orbit coupling alone. The order parameter is represented equivalently by a spin-1 spinor, a complex d-vector, and a pure-vector complex quaternion. Only the mapping and the density-spin bilinear are retained in the main text. A static Ginzburg–Landau functional then yields axial-polar, planar-polar, easy-axis polarized, and broken-axisymmetry mean-field states. Conservative Gross–Pitaevskii dynamics are introduced only as an additional composite-boson limit, not as a generic consequence of the Ginzburg–Landau theory. In that limit, analytic spectra are given for the axial-polar and easy-axis phases: the transverse spin branch softens at the axial-polar to broken-axisymmetry boundary, whereas crystal locking gaps the transverse magnon of the polarized phase. We do not claim a closed analytic spectrum for the mixed broken-axisymmetry phase. The static transverse current-response kernel provides a quantitative link between penetration-depth anisotropy and the gradient tensor. Ideal Bose condensation and BKT formulas are stated only in their controlled three- and two-dimensional limits. The framework therefore supplies a compact, falsifiable set of phase, mode, and response relations without introducing additional quaternionic degrees of freedom. Full article

Unmanned aerial vehicles (UAVs), also referred to as unmanned aerial pesticide application systems (UAPASs), are increasingly used for crop protection applications because of their operational efficiency and precision. However, UAV spraying is typically conducted at very-low volumes (VLVs) (10–20 L ha⁻¹), resulting in highly concentrated spray solutions that may alter formulation behavior relative to conventional ground applications. In this study, a total of nineteen commercially available herbicide, insecticide, and fungicide formulations representing multiple formulation classes were evaluated under UAV-relevant (10 L ha⁻¹) and conventional ground application conditions. Tank-mix compatibility, sprayability, droplet size distribution, driftable fines, dynamic surface tension (DST), and droplet spreading were assessed. Tank-mix incompatibility was most frequently observed in mixtures containing emulsifiable concentrate (EC) formulations, with five of 11 commonly used tank mixes exhibiting severe incompatibility at UAV rates despite compatibility at conventional application volumes. Formulations containing suspended actives, including suspension emulsions (SEs), suspension concentrates (SCs), oil dispersions (ODs), and water-dispersible granules (WDGs), showed the greatest risk of filter and screen clogging, whereas EC and soluble liquid (SL) formulations exhibited acceptable sprayability. UAV-rate spray solutions generally produced comparatively finer droplet spectra than ground-rate solutions, increasing driftable fines by up to 36.6% depending on formulation type. DST decreased by 2.5–35.2% under UAV conditions, with the largest reductions observed for SC and EC formulations. Reduced DST was associated with increased droplet spreading, particularly for fungicide formulations, where droplet spreading increased up to 718.8% relative to ground-rate preparations. These results demonstrate that formulation behavior can differ substantially under VLV conditions and that formulation-specific evaluation of compatibility, sprayability, atomization characteristics, and surface-tension-dependent behavior is required when products are deployed through UAV spray systems. Full article

While limestone calcined clay cement (LC3) can reduce CO₂ emissions by up to 50%, low early-age strength in low-clinker formulations limits its structural adoption. This study investigates practical strategies to accelerate early strength development in low-clinker LC3 mortars (clinker fraction ~42.5%) using sodium carbonate (1–3%) and a commercial chemical accelerator (1.5–3%), evaluated individually and in combination. Eleven mortar mixes were tested for compressive and flexural strength at 3, 7, and 28 days per BS EN 196-1, alongside ATR-FTIR hydration characterization and dry versus wet mixing comparisons. Results show that 2% sodium carbonate is the optimal single dosage, increasing 7-day compressive strength by ~29% (from 6.8 to 8.8 MPa) and flexural strength by 22% (from 2.46 to 3.00 MPa). Combining 1% sodium carbonate with 1.5% accelerator produced a pronounced synergistic effect, boosting 7-day compressive strength by 38% (9.4 MPa) and flexural strength by 34% (3.30 MPa). FTIR spectra confirmed enhanced silicate polymerization and carboaluminate precipitation. These findings provide construction practitioners with a scalable, low-cost chemical activation method to facilitate early demoulding and formwork stripping in sustainable low-carbon construction. Full article

Spectral unmixing of outdoor nighttime lighting mixtures is a linear but challenging problem due to spectral variability and contributions from unknown light sources. This paper presents a quadratic programming algorithm for constrained linear unmixing abundance estimation that extends the conventional fully constrained least squares approach through a physically motivated set of three linear constraints: estimated abundances must be non-negative, their sum must not be greater than unity, and the spectral signature reconstructed from estimated abundances must not exceed the measured signal in any spectral band. Unlike alternative optimization or neural network approaches, the proposed formulation requires no hyperparameter tuning or stochastic training, and yields a unique globally optimal solution whenever the endmember spectra are linearly independent, as verified for the case study considered here. The accuracy of the algorithm is evaluated using a physically motivated dataset generation framework grounded in the Generalized Linear Mixing Model, which is capable of modeling wavelength-dependent surface reflections and variable fractions of unknown light sources. Experiments conducted on a database of measured illumination sources demonstrate that the proposed formulation outperforms the classical fully constrained least squares baseline. Specifically, it reduces the abundance RMSE from 0.1539 to 0.1484 and improves the endmember detection F1 score from 0.795 to 0.803, with differences confirmed to be statistically significant. Furthermore, the model remains robust to surface reflections present in up to 80% of the evaluated mixtures. It maintains reliable abundance estimates for unknown spectral contributions up to approximately 15%, with accuracy gradually decreasing beyond this level. Finally, both the optimization method and the dataset generation framework are completely independent of the underlying channel configuration, making them readily adaptable to arbitrary choices of spectral channels and application domains beyond public lighting analysis. Full article

Microplastic pollution has become an emerging concern in feed safety and animal-derived food safety. This study applied near-infrared spectroscopy (NIR) combined with machine learning to perform qualitative and quantitative analysis of seven common microplastics in chicken feed, including polyamide (PA), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). A total of 840 samples with microplastic mass fractions ranging from 0.01% to 1.00% were prepared. Near-infrared spectra were acquired in the 1100–2200 nm range, and multiple spectral preprocessing methods and models were evaluated. The Synthetic Minority Over-sampling Technique (SMOTE) was introduced to assess the effect of data augmentation. For classification, the Extremely Randomized Trees (ET) model achieved the best performance, with an accuracy and F1-score of 0.9603 and 0.9602, respectively. For regression, performance varied among polymers, with PVC showing the best quantitative prediction performance using MA preprocessing combined with SVR (test set R² = 0.9851), while the raw-spectrum SVR model achieved R² = 0.9846 and RPD = 8.1642. Spectral preprocessing and data augmentation produced polymer-dependent changes in model performance. These results support portable NIR spectroscopy as a rapid, non-destructive screening approach under the controlled single-polymer conditions studied; mixed-polymer and field robustness require further validation. Full article

Economically motivated adulteration of olive oil, coffee and fruit juice is a persistent food-fraud problem for which Fourier-transform infrared (FTIR) spectroscopy with chemometrics offers rapid screening. Linear partial least squares (PLS) is interpretable but cannot capture non-linear mixing; neural networks add flexibility at the cost of becoming black boxes. We evaluated a Kolmogorov–Arnold network (KAN), which places learnable univariate functions on its edges and is therefore intrinsically interpretable, against PLS, support-vector regression, random forests, a multilayer perceptron and a one-dimensional convolutional network on three attenuated total reflectance (ATR)–FTIR datasets (olive oil + sunflower oil, coffee + malt flour, orange juice + apple juice; approximately 350, 400 and 400 spectra). All models were compared under identical, leakage-free validation that splits spectra by physical sample. The compact KAN was consistently competitive (cross-validated coefficients of determination (R²) = 0.86, 0.93 and 0.69) and yielded closed-form equations whose variables map to recognised vibrational bands and whose importance ranking agrees with SHapley Additive exPlanations (SHAP; Spearman ρ = 0.86–0.90); symbolic conversion costs no accuracy. We also report the following limits: PLS was strongest where the chemistry was linear (coffee) and the multilayer perceptron was strongest on fruit juice, whose equation is the weakest (R² = 0.47–0.75 across seeds); a parameter-matched perceptron matched the KAN’s accuracy; and leave-one-brand-out validation degraded every model. The KAN is therefore a promising, compact and genuinely transparent alternative under controlled multi-matrix conditions, not a deployment-ready method. Full article

In recent decades, old ideas of liquid water as a mixture of two distinct states, even at room temperature, resurged fueled by x-ray results that can be interpreted as fluctuating patches of high-density and low-density liquids. Isosbestic points in vibrational spectra indicate more strongly and more weakly hydrogen-bonded molecules, not necessarily patches. Despite mutual agreement among the fractions of the two states obtained from these experiments and with thermodynamic (two-state) and molecular models, chemical (example: water auto-dissociation) and interfacial (example: water surface tension) properties varying with temperature and salt content currently show opposite trends with the postulated fractions, which can therefore not be reconciled with a simple mixing model of the two states, whereas some physical properties (example: water static dielectric constant) can. Consequently, if the tale of two liquids were to be ultimately accepted and thermodynamic models for aqueous electrolyte solutions would need to be revised, then a simple mixing model would be insufficient with high probability. Full article

A Ni/Cu-containing phosphinate material based on 2-carboxyethyl(phenyl)phosphinic acid was synthesized under hydrothermal conditions and characterized using FT-IR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy) and EDAX (Energy Dispersive X-ray Analysis) analysis. The FT-IR spectra suggest the coordination of the phosphinate group to the metal, while SEM revealed compact aggregated particles of the compound. EDAX analysis confirmed the simultaneous presence of both Ni(II) and Cu(II) metals in the synthesized material. DFT (Density Functional Theory) calculations performed on the corresponding mononuclear Ni-CEPPA and Cu-CEPPA models indicated that the Cu complex possesses a smaller HOMO–LUMO energy gap (2.72 eV) than the Ni analog (3.43 eV), suggesting higher electronic reactivity. The obtained material was preliminarily evaluated for Methylene Blue removal, exhibiting an adsorption capacity of 170.24 mg/g. These results suggest that mixed Ni/Cu phosphinate materials may represent potential candidates for adsorption-related applications. Full article

Rolling-element bearings are a leading cause of unplanned downtime in continuous-process manufacturing, and the migration toward Industry 4.0 condition-based maintenance (CBM) has intensified the need for diagnostic methods evaluated on real in-service assets. This paper reports an exploratory, longitudinal single-asset industrial field demonstration of Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN)-based Hilbert spectral analysis for rolling-element bearing condition monitoring. An in-service bearing on a critical production machine was monitored over eight measurements spanning approximately four months and analyzed with the Hilbert–Huang Transform, using CEEMDAN in place of the classical Empirical Mode Decomposition to suppress mode mixing. The Hilbert spectra tracked the evolution of the bearing’s vibration signature as a growing concentration of vibration amplitude in a stable band of the 0–400 Hz analysis window (approximately 280–380 Hz); because the analysis characterizes the distribution of amplitude within the band rather than resolving discrete defect lines, this is reported as band-amplitude trending, and the band is treated as compatible with bearing-related excitation rather than attributed to a specific kinematic fault frequency. At the final pre-replacement measurement (M8), a bounded consistency cross-check against a conventional single-sided Fast Fourier Transform (FFT) amplitude spectrum computed from the same exported waveform recovered co-located dominant content. This establishes cross-method consistency for the measurement examined, but does not independently validate diagnostic correctness or the full campaign trend. Interpretability of the representation is argued qualitatively and remains to be tested. The contribution is therefore the documented field application and its explicit consistency cross-check procedure; applicability beyond this asset and its operating conditions requires multi-asset evaluation. Full article

A strong relationship has been revealed between the topography of the Vema Fracture Zone and spectra of temperature estimated from profiles of CTD casts. Internal waves over rough topography transform the vertical profiles of temperature, as revealed from the data of usual CTD casts. Internal waves generate fine structure in vertical profiles. Variations in the shape of temperature profiles cause variations in one-dimensional spatial spectra of vertical displacements estimated from temperature profiles. Spectral estimates (“dropped spectra”) from profiles over rough topography exceed those estimated over flat topography. In the latter case, they are much closer to the dropped spectra of the Garrett–Munk model. Full article

(Bi_0.5Na_0.5)TiO₃ (BNT)-based ceramics have attracted much attention for energy storage applications, but some fundamental issues remain unclear—in particular, how the conduction mechanism changes with composition and what role oxygen vacancies play. The (0.95−x)[(Bi_0.5Na_0.5)_(1−1.5y)Sm_y](Zr_0.2Ti_0.8)O₃-0.05BiFeO₃-xBa(Sn_0.2Ti_0.8)O₃ (abbreviated as (0.95−x)BNSmZT-0.05BF-xBaSnT, x = 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, y = 0.01) system was investigated, where Ba(Sn_0.2Ti_0.8)O₃ (BaSnT) content varies from 0.05 to 0.4. A non-monotonic conduction transition is revealed by the conductivity and relaxation behavior characterized by impedance spectroscopy and dielectric temperature spectra combined with electric modulus analysis. At low BaSnT (x ≤ 0.1), residual Bi₂Ti₂O₇ at grain boundaries blocks oxygen vacancy migration, giving high activation energy (~2.12 eV) and presenting oxygen vacancy-mediated conduction. At x = 0.15, the impurity disappears and free oxygen vacancies surge, dropping the activation energy to 1.21 eV, corresponding to oxygen-vacancy-dominated ionic conduction with increased carrier density. For x = 0.2–0.4, strong Ba-O-Bi bonds stabilize the migration barrier around 1.57 eV, resulting in mixed oxygen vacancy-mediated conduction. The optimal composition 0.75BNSmZT-0.05BF-0.2BaSnT shows the best dielectric stability and highest resistance. From modulus master curves and broadened M″ peaks, the conduction is identified as correlated hopping of oxygen vacancies, consistent with non-Debye relaxation. This work provides a clear picture of how oxygen vacancy dynamics depend on phase purity, grain boundaries, and A-site chemistry in the BNT-based lead-free ceramics. Full article