Search Results (7,385)

The photocatalytic activity of silica–titania (S-T) fibers synthesized via sol–gel and electrospinning was evaluated using methyl orange (MO), eriochrome black T (EB), and methylene blue (MB) as model dyes. Characterization by X-ray diffraction confirmed the presence of anatase and rutile TiO₂ phases, while UV-Vis spectroscopy determined a bandgap energy of 3.2 eV. Scanning electron microscopy revealed fibers with an average diameter of 214 nm. Under UV irradiation, nearly complete dye removal (initial concentration: 30 mg/L; catalyst dosage: 0.1 g/L) was achieved within 8 h. The reaction kinetics followed the Langmuir–Hinshelwood model, with significant differences in apparent reaction rates (k_a) among the dyes, attributable to their distinct structural and functional properties. This study establishes silica–titania fibers as a high-performance, highly versatile composite photocatalyst. Achieving 98% degradation efficiency, their key innovation is their fibrous morphology, which solves the critical problem of powder catalyst recovery. This enables a paradigm shift from simple lab efficiency to practical, sustainable application. Full article

The aim of this study is to evaluate the usefulness of UV-Vis-NIR spectroscopy as a tool for detecting the adulteration of cold-pressed walnut oil and other edible oils (rapeseed, sunflower, and soybean oils) at varying percentages. The spectra were recorded between 200 and 1800 nm, but the analyses focused on 350–1650 nm due to high UV and NIR absorption. Color was determined in CIEL*a*b* coordinates to achieve the differences among the samples. The spectra were submitted to several pre-treatment (none, normalization, SNV, MSC, baseline/detrend, first/second derivative, and 1st-order smoothing) to improve the statistical model’s parameters. The differentiation of the samples was carried out using an unsupervised method (principal component analysis—PCA) and two supervised methods (linear discriminant analysis—LDA and partial least squares linear discriminant analysis—PLS-DA). Partial least squares regression (PLS-R) was used for predicting the degree of adulteration. Separation between the authentic and adulterated samples was visible in the PCA scores plot, primarily along the spectral regions of 420–500 nm (pigment-related absorption band) and 1150–1450 nm (lipid-associated band). PLS-DA was superior to DA for the discrimination of authentic/adulterated samples, with baseline spectra of 350–1650 nm yielding a 100% overall accuracy and near-perfect accuracy with MSC (98.48%). PLS-R was able to predict the adulteration level, depending on the pre-treatment applied. Full article

In the current research a series of new copper(II) complexes with novel acylhydrazone ligands were synthesized and their antibacterial and anticancer activities were determined. The complexes were characterized by molecular spectroscopy (FT-IR and UV-Vis) and conductivity measurements. Additionally, their structure was confirmed by single-crystal X-ray analysis. The crystallographic data revealed that all compounds are mononuclear Cu(II) species. The Cu(II) ion is four-coordinated by the ONO donor set from mono-deprotonated hydrazone ligand and one Cl^¯ anion, forming distorted square-planar geometry. The biological studies revealed that the compounds exhibit high antimicrobial activity, especially against Gram-positive bacteria, in some cases greater than the reference substances, and better activity than free ligands. The tested complexes possessed the lowest MIC and MBC values towards Staphylococcus epidermidis ATCC 12228 and Micrococcus luteus ATCC 10240. Furthermore, they showed no toxicity towards normal cell lines. Full article

(Zn_1−xCo_x)₃Mo₂O₉ (0 ≤ x ≤ 0.15) samples were synthesized as novel inorganic violet pigments by a conventional solid-state reaction method, and the obtained powders were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), ultraviolet and visible (UV-Vis) diffuse reflectance spectroscopy, and L*a*b*Ch° chromatic coordinates. The Co²⁺-doped samples showed optical absorption at wavelengths of 500−560 and 680 nm, which were attributed to the d–d transitions of Co²⁺, resulting in a violet color. The absorption intensity increased with increasing the Co²⁺ concentration. The most vibrant violet color was obtained with a composition of (Zn_0.90Co_0.10)₃Mo₂O₉. Full article

The current study evaluates the characteristics of electrospun PVDF-based membranes doped with zeolite-A in terms of their structural, morphological, thermal, mechanical, hydrophobic, optoelectrical, and adsorption properties. The effects of the DMF–acetone ratio on solvent and zeolite-doping concentration have been evaluated using SEM-EDX, BET, Raman, XRD, DSC-TGA, UV-VIS spectroscopy, contact angle measurements, and mechanical testing. The membranes prepared with solvents low in acetone and increased zeolite content exhibited a higher crystallinity degree exceeding 50%. Zeolite-enriched membranes have a slightly higher content in the α crystalline phase of PVDF when compared to zeolite-free membranes. Electrospinning processing decreased the sample’s subcooling, improving its thermal stability. Zeolite-doping reduced the band gap energy to 1.3 eV from a maximum of 2.7 eV in PVDF membranes. Membranes doped with 3 or 4 wt.% zeolite exhibit improved load-elongation values at break, reaching up to 4.2 N and 47 mm, respectively, and increased flexibility due to their porous structures and the ratio of crystalline to amorphous phases. The membranes adsorbed an MB equilibrium quantity up to 18.5 mg/g and obeyed the pseudo-second-order (PSO) kinetic model within the first 24 h. Thus, the synergistic effect of zeolite content and solvent ratio can effectively adjust the sample’s structure, texture, and properties. Full article

Mg-doped gallium oxide films were prepared on single crystal sapphire substrates through radio frequency magnetron sputtering technology, and then AlN films of different thicknesses were deposited on them as passivation layers. Finally, Pt interdigitated electrodes were prepared through mask plate and ion sputtering technology to make metal–insulator–semiconductor–insulator–metal (MISIM) photodetectors. The influence of the AlN passivation layer on the optical properties and photodetection performance of the device was investigated using UV-Vis (ultraviolet-visible absorption spectroscopy) spectrophotometer and a Keith 4200 semiconductor tester. The device’s performance was significantly enhanced. Among them, the MISIM-structured device achieves a responsivity of 2.17 A/W, an external quantum efficiency (EQE) of 1100%, a specific detectivity (D*) of 1.09 × 10¹² Jones, and a photo-to-dark current ratio (PDCR) of 2200. The results show that different thicknesses of AlN passivation layers have an effect on the detection performance of Mg-doped β-Ga₂O₃ films in the UV detection of the solar-blind UV region. The AlN’s thickness has little effect on the bandgap when it is 3 nm and 5 nm, and the bandgap increases at 10 nm. The transmittance of the film increases with the increase in AlN thickness and decreases when the AlN’s thickness increases to 10 nm. The photocurrent exhibits a non-monotonic dependence on AlN thickness at 10 V, and the dark current gradually decreases. The thickness of the AlN passivation layer also has a significant impact on the response characteristics of the detector, and the response characteristics of the device are best when the thickness of the AlN passivation layer is 5 nm. The responsiveness, detection rate, and external quantum efficiency of the device first increase and then decrease with the thickness of the AlN layer, and comprehensive performance is best when the thickness of the AlN passivation layer is 5 nm. The reason is that the AlN layer plays a passivating role on the surface of Ga₂O₃ films, reducing surface defects and inhibiting its capture of photogenerated carriers, while the appropriate thickness of the AlN layer increases the barrier height at the semiconductor interface, forming a built-in electric field and improving the response speed. Finally, the AlN layer inhibits the adsorption and desorption processes between the photogenerated electron–hole pair and O₂, thereby retaining more photogenerated non-equilibrium carriers, which also helps enhance photoelectric detection performance. Full article

Reactions of anhydrous Zn(II) iodides with redox-active 1,4-diaza-1,3-butadiene (DAD) and its bis(imino)acenaphtene (BIAN) derivatives in absolute acetonitrile yielded a series of new complexes: [(Mes-DAD)ZnI₂] (1), [(dpp-DAD)ZnI₂] (2), and [(dpp-BIAN)ZnI₂] (3). Single crystals of all compounds were obtained, and their molecular structures were unambiguously determined by X-ray diffraction analysis. Purity of bulk samples in solid state was confirmed by PXRD. Stability of the complexes in solution was investigated by means of UV-Vis and NMR spectroscopy. Cyclic voltammetry revealed two or three quasi-reversible reduction waves in the cathodic region for complexes 1–3. The ability of 3 to accept up to three electrons highlights the potential of these compounds as electrocatalysts for reductive transformations. Full article

To investigate the deterioration pattern of the rheological properties of high-viscosity high-elasticity asphalt (HVEA) under UV and salt freeze–thaw (SFT) cycle environments, two snowmelt salts were used for coupled aging tests, along with temperature sweep, bending beam rheological (BBR), and Fourier-transform infrared spectroscopy (FT-IR) tests. The results showed that both snowmelt salts could enhance the high-temperature rutting resistance of HVEA, in which the enhancement effect of NaCl was more significant. With the increase in salt concentration, the BBR stiffness of HVEA decreased and then increased, while the m-value showed the opposite trend, indicating that the addition of snowmelt salt impaired its low-temperature creep performance. Additionally, UV-SFT aging would exacerbate the degradation of low-temperature crack resistance. The temperature sensitivity of HVEA gradually decreased with the drop of viscosity temperature sensitivity (VTS) value; salt corrosion further significantly reduced its temperature sensitivity. UV-SFT aging would significantly weaken fatigue performance of HVEA, especially after 15 cycles. FT-IR test showed that UV-SFT resulted in the enhancement of S=O and C=C characteristic peaks, suggesting that the HVEA underwent oxidization and chemical aging, which increased the low-temperature brittleness. Full article

Green nanotechnology offers a sustainable and eco-friendly approach for nanoframework synthesis. The present study intended to synthesize a novel eco-friendly encapsulated Zeolitic Imidazolate Framework-8 (ZIF-8) in a one-pot method using metabolites from the mangrove plant Conocarpus erectus (CE). Gas Chromatography–Mass Spectrometry (GC-MS) analysis of the extract revealed the presence of important bioactive metabolites. The synthesized material was evaluated by UV-Vis spectroscopy, X-ray diffraction (XRD), particle size analysis (PSA), zeta potential measurement, high-resolution transmission electron microscopy (HR-TEM), and Fourier transform infrared (FT-IR) spectroscopy studies. The environment-friendly mangrove metabolites aided by Zeolitic Imidazolate Framework-8 was found to be crystalline, rhombic dodecahedron structured, and size dispersed without agglomeration. The nanomaterial possessed a broad antimicrobial effect on drug-resistant microorganisms, including Candida krusei, Escherichia coli, Streptococcus Sp., Staphylococcus aureus, Enterococcus Sp., Pseudomonas aeruginosa, Klebsiella pneumoniae, C. propicalis, and C. albicans. Further, its cytotoxicity against MDA-MB-231 cells was found to be efficient. The morphological alterations exhibited by the antiproliferative impact on the breast cancer cell line were detected using DAPI and AO/EB staining. Therefore, ZIF-8 encapsulated mangrove metabolites could serve as an effective biomaterial with biomedical properties in the future. Full article

Hair can be significantly damaged following exposure to environmental agents and physical and chemical treatments. The aim of this study concerned the evaluation of the protective and restructuring efficacy of a hair mask containing two rice derivatives: rice germ oil GX-N and ferulic acid. This evaluation was performed on hair damaged by bleaching, UV irradiation, and heat treatment by applying the following techniques: FT-IR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), a stress–strain test, polarized light microscopy analysis, and protein loss determination. The application of the masks highlighted an improvement in the characteristics of the hair. Rice germ oil GX-N showed very interesting and protective properties in all the treatments; however, the inclusion of a low concentration of ferulic acid did not provide additional benefits. Full article

We report the synthesis, spectroscopic, structural, and ultrafast photophysical investigation of a series of homoleptic and heteroleptic Zn(II) complexes based on the donor-acceptor β-diketonate ligand 4,4,4-trifluoro-1-phenylbutane-1,3-dione. Mass spectrometry, infrared, and NMR analyses confirm complexation and indicate possible fragmentation pathways involving the sequential loss of β-diketonate ligands. Single-crystal X-ray diffraction revealed that all complexes adopt monomeric octahedral geometries, with the ancillary nitrogen-based ligands introducing variable distortions. Thermal analyses confirmed that the complexes are non-volatile and have an onset >250 °C, with thermal decomposition primarily to ZnO and ZnF₂. Complexes with aromatic Lewis base led to higher residue percentages, likely due to the final graphitic carbon content. UV-Vis absorption and femtosecond transient absorption spectroscopy demonstrate that the chelated β-diketonate ring serves as the main optically active chromophore, a property unaffected by the nitrogen ligands. The free ligand undergoes rapid internal conversion, whereas coordination to Zn stabilizes the triplet state via LMCT, producing long-lived and chemically reactive species relevant to dissociation processes. This study demonstrates how tailored ligand environments can be exploited to tune excited-state properties, offering a rational framework for the design of functional precursors suitable for nonlinear photolysis and advanced nanomaterial synthesis. Full article

Carbon quantum dots (CQDs) are photoluminescent nanomaterials (<10 nm) with excellent hydrophilicity, biocompatibility, and low cytotoxicity, making them attractive for biological applications. However, their use in aquaculture nutrition has remained largely unexplored. This study investigated the effects of dietary CQDs on zebrafish (Danio rerio), a model organism with approximately 70% genetic homology with humans. CQDs were synthesized hydrothermally from unripe Citrus limon and characterized by UV–visible (UV-Vis) spectroscopy, UV–vis transillumination, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FT-IR), and photoluminescence (PL) spectroscopy. Zebrafish were fed diets containing varying CQD concentrations, and growth performance, condition factor (K), hematological parameters, enzymatic activity, and tissue morphology were assessed. Feeds supplemented with 2 mL CQDs produced significant improvements in growth and biochemical indicators without adverse effects. Hematological and enzymatic profiles remained within normal ranges, and histological examination revealed no morphological abnormalities, indicating the absence of toxicity. These findings suggest that citrus-derived CQDs can enhance zebrafish growth and maintain physiological health, thereby supporting their potential as safe functional feed additives in aquaculture. This approach may open new opportunities for the application of CQDs in sustainable fish farming and the broader food industry. Full article

Eleven novel asymmetric pyrimidine derivatives were synthesized. The pyrimidine core was functionalized with a coumarin chromophore and a pro-mesogenic fragment bearing either chiral or linear alkyl chains of variable length and substitution patterns. The thermal properties were investigated using polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering, revealing that only selected derivatives exhibited liquid crystalline phases with ordered columnar or smectic organizations. Linear and nonlinear optical properties were characterized by UV–Vis absorption, fluorescence spectroscopy, two-photon absorption, and second-harmonic generation. Optical responses were found to be highly sensitive to the substitution pattern: derivatives functionalized at the 4 and 3,4,5 positions exhibited enhanced 2PA cross-sections and pronounced SHG signals, whereas variations in alkyl chain length exerted only a minor influence. Notably, compounds forming highly ordered non-centrosymmetric mesophases produced robust SHG-active thin films. Importantly, strong SHG responses were obtained without the need for a chiral center, as the inherent asymmetry of the linear alkyl chain derivatives was sufficient to drive self-organization into non-centrosymmetric materials. These results demonstrate that asymmetric pyrimidine-based architectures combining π-conjugation and controlled supramolecular organization are promising candidates for nonlinear optical applications such as photonic devices, multiphoton imaging, and optical data storage. Full article

Green synthesis methods of silver nanoparticles have gained great attention because they offer sustainable, eco-friendly, and less-toxic alternatives to traditional methods. This study sheds light on the green synthesis of chitosan silver nanoparticle composites, providing a comparative evaluation of microwave-assisted (M1) and a one-pot (M2) reduction methods. The morphological, crystallinity, and structural uniformity characteristics were evaluated by UV-Visible, Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) with employing image processing pipeline based on deep learning model for segmentation and particles size estimation. The UV-visible spectrum exhibited independent SPR peaks ranging from 400 to 450 nm for all samples; however, microwave assisted-synthesis possessed narrower and more intense peaks indicative of better crystallinity and mono-dispersity. SEM depicted smaller, more uniformly dispersed particles for microwave-assisted (M1), while deep learning segmentation showed lower particle size variability (σ ≈ 24–43 nm), compared to polydisperse (σ ≈ 16–59 nm) in M2 samples. XRD showed crystalline face-centered cubic (FCC) silver with dominant peaks in M1 samples, whereas M2 had broader, less intense peaks with amorphous features. Raman vibrations revealed more structural order and homogenous capping in M1 than M2. Therefore, microwave-assisted (M1) showed better control on nucleation, particle size, crystallinity, and homogeneity due to a faster and uniform energy distribution. The future research would focus on the antimicrobial evaluation of such nanoparticles in agronomy. Full article

In this study, molybdenum disulfide (MoS₂)-based water nanofluids were prepared and stabilized using two surfactants with opposite charges: the cationic cetyltrimethylammonium bromide (CTAB) and the anionic sodium lauryl sulfate (SLS). Different MoS₂:surfactant ratios (1:1, 1:2, and 1:3) were examined to identify the optimal formulation ensuring stable dispersion. Stability was evaluated through dynamic light scattering (DLS), zeta potential, and UV–Vis spectroscopy analyses. The results showed that the MoS₂:SLS (1:3) nanofluid achieved the highest stability, characterized by a zeta potential of −38 mV and a mean particle size of approximately 290 nm. Thermophysical properties were then investigated for nanoparticle concentrations of 0.05, 0.1, and 0.2 wt%. The 0.1 wt% nanofluid exhibited the best performance, showing a thermal conductivity enhancement of about 49% and an increased specific heat capacity compared with pure water. This improvement is attributed to uniform nanoparticle dispersion and enhanced phonon transport. Overall, the results demonstrate that the anionic SLS surfactant at a 1:3 ratio effectively enhances the stability as well as the thermal performance of MoS₂–water nanofluids, making them promising candidates for thermal management and energy systems applications. Full article