Search Results (767)

Cytisine and coumarin derivatives are promising for the creation of new drugs with antiarrhythmic, antiepileptic, antidiabetic, anti-inflammatory, and antimicrobial effects. In this study, the molecular structure of the cytisine and coumarin derivative in solution, a recently synthesized substance N-(2-oxo-2H-chromen-3-carbonyl)cytisine, was studied by NMR and UV-Vis absorption spectroscopies accompanied by a theoretical study based on density functional theory. The existence of four stable conformers associated with the rotation of the cytisine part relative to the coumarin part due to a sufficiently flexible intermediate part has been demonstrated. Their energy and concentrations were estimated. In the 1H and 13C NMR spectra, peaks were found that correspond to individual conformers and groups of conformers. The UV-visible absorption spectrum also revealed spectral features associated with different conformers. It was shown that the obtained results are consistent with earlier studies about conformational state identification in cytisine derivatives functionalized with flexible parts. The obtained theoretical and experimental results provide useful spectroscopic information for such conformer identification in this and structurally similar substances. Full article

Ultraviolet-light emitting diodes (UV-LEDs) offer several advantages over conventional mercury-based UV lamps, including wavelength selectivity, compact size, design flexibility, instant on/off, power output adjustment, and mercury-free operation. These features position UV-LEDs as ideal candidates for point-of-use (POU) water disinfection systems, particularly in decentralized or resource-limited environments. In this study, we evaluated the microbial inactivation performance and energy efficiency of a bench-scale flow-through UV-LED POU system using indigenous heterotrophic plate count (HPC) bacteria, E. coli, and MS2 bacteriophage. The system was tested under various flow rates (1–4 L/min) and wavelength configurations (265 nm, 278 nm, and dual-wavelength combinations). MS2 bacteriophage was further used in collimated beam testing to validate UV-fluence-response curves and to estimate delivered doses in the flow-through POU device. HPC inactivation was enhanced under dual-wavelength conditions, suggesting wavelength-specific synergy, while E. coli showed high susceptibility across all wavelength configurations, achieving >2-log inactivation at significantly reduced UV-LED power (1/6 of that required for HPC) even at 4 L/min. Specific energy consumption analysis showed energy demands as low as 0.032–0.053 kWh/m³ for achieving 4-log inactivation of E. coli, with an estimated annual operating cost for UV-LED irradiation below $1.70. These findings demonstrate the potential of UV-LED-based POU devices as safe, energy-efficient, and cost-effective technologies for decentralized water treatment. Full article

Background: Measurement uncertainty (MU) is a crucial parameter for ensuring the reliability of analytical methods and the validity of results, as required by ISO 17025:2017. Its estimation is particularly critical for quality control laboratories, where compliance decisions are based on a rigorous interpretation of uncertainties. Methods: In this study, we evaluated the uncertainty associated with an HPLC-UV method for the determination of Metopimazine (MPZ) in a pharmaceutical form, applying two complementary approaches: The ISO-GUM (Guide to the Expression of Uncertainty in Measurement) top-down approach and the Monte Carlo Simulation (MCS). Results: The results of both approaches showed excellent agreement, thus validating the robustness of the evaluation. The analysis of uncertainty sources revealed that the accuracy of the sample volume (V_Sample) and the calibration standard (C_x) were the dominant contributors, representing 39.9% and 36.2% of the total uncertainty, respectively. Combined, these two factors accounted for 76.1% of the variability, underscoring their critical impact on the assay’s precision. The expanded uncertainty (k = 2, 95% confidence level) was determined to be (99.41 ± 0.69)%, reflecting the method’s reproducibility. Conclusions: These results highlight the importance of rigorously controlling calibration standard preparation, sample volume, and repeatability conditions to optimize the reliability of the assay. Full article

Today, the abundance of personal care product (PCP) ingredients and UV filters (UVFs) in coastal marine environments is a growing concern worldwide. In addition, mussels are the most commonly used sentinel organisms in bio-monitoring programs. In the current study, we collected mussels (Mytilus galloprovincialis) (over 6 months) from three seawater sites in Tunisia (Monastir, Sousse, and Mahdia). Analysis of the samples by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) revealed the presence of 13 compounds among the 18 PCP ingredients and UVFs investigated. Avobenzone (AVO) and tert-butyl hydroxyphenyl benzotriazole (TBHPBT) were the most frequently observed, ranging from 121.076 ± 1.6 to 193.481 ± 5.5 ng g⁻¹ and 20.987 ± 0.7 to 26.704 ± 1.7 ng g⁻¹, respectively, with maximum values in the city of Sousse. 4-Hydroxybenzophenone (4HB) and benzophenone-1 (BP1) were also found in all mussel samples with levels in the range of 26.745 ± 0.4 ng g⁻¹ and 12.53 ± 0.5 ng g⁻¹, respectively. We observed a positive correlation with the chemical characterization of the contaminated seawater. The environmental hazards of PCP ingredients were estimated with the aim of performing a preliminary risk assessment at the environmental level. For this purpose, the estimated daily intake (EDI) of a substance was calculated. The results obtained revealed a high value of up to 68.36 ng kg body-weight⁻¹ day⁻¹. The high concentration observed in the samples reported for the target PCP ingredients could be partly attributed to their inefficient removal before being released into the sea. We now know that PCP ingredients and UVFs cause irreparable damage to coastal ecosystems and pose the greatest risk to the aquatic organisms tested. Full article

Spectral detection technology offers non-destructive, in situ, and high-speed capabilities, making it widely applicable for detecting biological and chemical samples and quantifying their concentrations. Water resources, essential to life on Earth, are widely distributed across the planet. The application of spectral technology to underwater environments is useful for wide-area water resource monitoring. Although spectral detection technology is well-established, its underwater application presents challenges, including waterproof housing design, power supply, and data transmission, which limit widespread application of underwater spectral detection. Furthermore, underwater spectral detection necessitates the development of compatible computational methods for sample classification or regression analysis. Focusing on underwater spectral detection, this work involved the construction of a suitable hardware system. A compact spectrometer and LEDs (400 nm–800 nm) were employed as the detection and light source modules, respectively, resulting in a compact system architecture. Extensive tests confirmed that the miniaturized design-maintained system performance. Further, this study addressed the estimation of total phosphorus (TP) concentration in water using spectral data. Samples with varying TP concentrations were prepared and calibrated against standard detection instruments. Subsequently, classification algorithms applied to the acquired spectral data enabled the in situ underwater determination of TP concentration in these samples. This work demonstrates the feasibility of underwater spectral detection for future in situ, high-speed monitoring of aquatic biochemical indicators. In the future, after adding UV LED light source, more water quality parameter information can be obtained. Full article

This work assesses sulfur dioxide (SO₂) emissions from two power plants in Baja California Sur, Mexico, using ground-based UV camera measurements and AERMOD dispersion modeling. Field campaigns conducted during 2022 in La Paz and Puerto San Carlos captured spatial and temporal variations in SO₂ slant column densities (SCDs) and fluxes, revealing higher emissions at the larger Punta Prieta (CTPP) thermoelectric power facility (mean flux: 1.13 kg s⁻¹) compared to the Agustín Olachea (CCI AO) internal combustion power plant (mean flux: 0.59 kg s⁻¹). The UV camera effectively monitored plume structure and dynamics, with error analyses indicating uncertainties of ~12% in flux estimates. AERMOD simulations showed ground-level SO₂ concentrations exceeding WHO and Mexican air quality standards near the plants, with localized exposure risks particularly for workers. The results underscore the substantial contribution of these facilities to regional SO₂ pollution and demonstrate the utility of combining remote sensing with modeling to assess industrial emissions and inform air quality management in sensitive regions. Full article

This research focuses on the synthesis, characterization, and photocatalytic performance of Cu-based polyoxometalate (Cu-POM) as an effective catalyst for the degradation of organic dyes, specifically Congo Red (CR) and Phenol Red (PR). The main goals are to synthesize Cu-POM using a controlled self-assembly technique, characterize its optical and structural characteristics using FTIR, XRD, SEM, TGA, and UV-Vis spectroscopy, and estimate its photocatalytic activity when exposed to UV light. The outcomes confirm the successful formation of Cu-POM with well-defined nanostructures and a crystalline polyoxometalate framework. The determined optical bandgap of 3.65 eV indicates its strong UV-light responsiveness. The photocatalytic degradation experiments demonstrated high removal efficiencies of 58.1% for CR and 64.6% for PR under UV irradiation, corresponding kinetic rate constants of 0.00484 min⁻¹ and 0.00579 min⁻¹, respectively. The superior photocatalytic activity is attributed to the efficient charge carrier separation and high surface area of Cu-POM. These findings highlight the potential of Cu-POM as a promising heterogeneous photocatalyst for sustainable wastewater treatment and environmental remediation. Full article

Cable-driven parallel robots (CDPRs) offer large workspaces with minimal infrastructure, but their control becomes difficult when the platform is under-constrained and sensing is limited. This paper investigates uncalibrated visual servoing (UVS) with a single monocular camera, asking whether simple global static Jacobians (GSJ) can be sufficient and how an adaptive Jacobian estimator behaves. Two platforms are evaluated: a three-cable (3C) platform and a redundant six-cable du-al-plane platform (RC). Motion-capture (MoCap) validation shows that redundancy improves stability and tracking by reducing platform tilt and making image errors correspond more directly to Cartesian motions. Across static and low-speed tracking tasks, GSJ proved reliable, while a baseline recursive least-squares (RLS) estimator without safety triggers was often unstable. These findings suggest that improving mechanical conditioning may be as important as adding algorithmic complexity, and that carefully estimated global models can suffice in practice. Limitations include the use of a single camera, laboratory conditions, and a baseline RLS variant; future work will evaluate event-triggered adaptation and higher-speed trajectories. Full article

Monitoring and accurately forecasting ultraviolet (UV) radiation is of great importance especially due to its adverse effects on human health. In this study, we develop a numerical model to estimate the UV surface solar radiation with the overarching goal of providing a fully automated UV forecasting tool in the region of Epirus, Greece, and especially at the city of Ioannina. The UV surface solar radiation (SSR) is estimated based on detailed radiative transfer (RT) calculations. To ensure their accuracy, we employ the well-established UVSPEC model included in the libRadtran RT routines. LibRadtran provides a variety of options to set up and modify an atmosphere with molecules, aerosol particles, water and ice clouds and a surface as the lower boundary. As a first step, we performed a sensitivity study of the surface solar UV radiation with respect to ozone, precipitable water, aerosol optical properties and surface albedo. Our calculations are performed initially under clear-sky conditions to eliminate the uncertainties induced by clouds. All our calculations are performed spectrally within the UV spectral range, for a specific date and time at Ioannina, Epirus. Full article

The nutritional and commercial value of lettuce (Lactuca sativa L.) is determined by its foliar pigment and phenolic composition, which varies among cultivars. This study aimed to assess the capacity of hyperspectral and applied multispectral imaging, combined with machine learning algorithms, to predict and map key biochemical traits, such as chloroplastidic pigments (chlorophylls and carotenoids) and extrachloroplastidic pigments (anthocyanins, flavonoids, and phenolic compounds). Eleven cultivars exhibiting contrasting pigmentation profiles were grown under controlled greenhouse conditions, and their chlorophyll a and b, carotenoid, anthocyanin, flavonoid, and total phenolic contents were evaluated. Spectral reflectance data were acquired via a Headwall hyperspectral sensor and a MicaSense multispectral sensor, and the pigment contents were quantified via solvent extraction and a UV microplate reader. We developed predictive models via seven machine learning approaches, with partial least squares regression (PLSR) and random forest (RF) emerging as the most robust algorithms for pigment estimation. Chlorophyll a and b are highly and positively correlated (r > 0.9), which is consistent with their hyperspectral reflectance imaging results. The hyperspectral data consistently outperformed the multispectral data in terms of predictive accuracy (e.g., R² = 0.91 and 0.76 for anthocyanins and flavonoids via RF) and phenolic compounds with R² = 0.79, capturing subtle spectral features linked to biochemical variation. Spatial maps revealed strong genotype-dependent heterogeneity in pigment and phenolic distributions, supporting the potential of this approach for cultivar discrimination and pigment phenotyping. These findings demonstrate that hyperspectral imaging integrated with data-driven modelling offers a powerful, nondestructive framework for the biochemical monitoring of leafy vegetables, supporting breeding, precision agriculture, and food quality assessment. Full article

The ability of enzymes to access various conformational states is often essential for their catalytic activity. Lysine 5,6-aminomutase (5,6-LAM), a pyridoxal 5′-phosphate (PLP) and 5′-deoxyadenosylcobalamin (dAdoCbl)dependent enzyme, catalyzes 1,2-amino shift in lysine isomers by shuttling between an open conformational state and a closed conformational state. Nevertheless, suicide inactivation of 5,6-LAM is an obstacle to the realization of its potential as a biocatalyst. In this work, the fate of the reaction of 5-hydroxylysine, an analogue of lysine, is investigated using spectroscopic and computational methods. Although 5-hydroxylysine does not afford any product, results obtained from UV–visible and electron paramagnetic resonance (EPR) spectroscopies demonstrate that initial steps of the catalytic cycle are performed with it. Simulation of the weakly spin-coupled spectrum estimates an intermediate distance between the PLP substrate-based radical and Co(II) in comparison to the that in the open state and the closed state. This distinct conformational state, different from the open state and the closed state, is alluded to in its putative role in suicide inactivation and denoted as the suicidally-inactivated state. Our findings highlight the emergence of EPR spectroscopy as a powerful tool to uncover the hidden conformations in radical enzymes. These results provide new insights into the suicide inactivation of dAdoCbl-dependent enzymes. Full article

The European Circular Economy Action Plan outlines a forward-looking strategy that emphasizes waste reduction and the acquisition of high-quality secondary resources. Previous research has shown that cocoa processing by-products contain compounds of interest for various industrial areas, making them an attractive matrix for reuse. However, a gap remains in our understanding of the safety of these by-products intended for feed. In this study, theobromine and caffeine were quantified by High-Performance Liquid Chromatography (HPLC-UV) in cocoa hulls for safety considerations, evaluating theobromine compliance with toxicological and safety levels, and considering their potential application as an ingredient in animal feed. In addition, the identification of phenolic components and associated antioxidant activity was conducted through High-Performance Thin-Layer Chromatography (HPTLC). This preliminary study indicates that theobromine content is a limiting factor for the inclusion of cocoa hulls in animal diets, as it restricts inclusion levels to remain within current regulatory limits. Examples of general estimates of dietary theobromine exposure at inclusion levels based on regulatory limits for dairy cows and veal calves confirmed a low risk for animal health. Furthermore, the detection of antioxidant activity linked to the presence of polyphenols highlights the potential of cocoa hulls as a sustainable food by-product for feed formulation. Full article

This work reports a low-cost, microwave-assisted wet chemistry synthesis of zinc antimonate (ZnSb₂O₆) powders with a trirutile structure, yielding highly homogeneous, nanometric particles. X-ray diffraction (XRD) confirmed the formation of the trirutile phase with lattice parameters of a = 4.664 Å and c = 9.263 Å, and an estimated crystallite size of 42 nm. UV–vis spectroscopy revealed a bandgap of 3.35 eV. Scanning electron microscopy (SEM) showed that ethylenediamine, as a chelating agent, formed porous microstructures of microrods and cuboids, ideal for enhanced gas adsorption. Brunauer–Emmett–Teller (BET) analysis revealed a specific surface area of 6 m²/g and a total pore volume of 0.0831 cm³/g, indicating a predominantly mesoporous structure. The gas sensing properties of ZnSb₂O₆ pellets were evaluated in CO and C₃H₈ atmospheres at 100, 200, and 300 °C. The material exhibited high sensitivity at 300 °C, where the maximum responses were 5.86 for CO at 300 ppm and 1.04 for C₃H₈ at 500 ppm. The enhanced sensitivity at elevated temperatures was corroborated by a corresponding decrease in electrical resistivity. Furthermore, the material demonstrated effective photocatalytic activity, achieving up to 60% degradation of methylene blue and 50% of malachite green after 300 min of UV irradiation, with the process following first-order reaction kinetics. These results highlight that ZnSb₂O₆ synthesized by this method is a promising bifunctional material for gas sensing and photocatalytic applications. Full article

Green synthesis of gold nanoparticles (AuNPs) provides a significantly eco-friendly and low-impact counterpart to conventional chemical methods. In the present study, we synthesized gold nanoparticles using Schinus molle (P-AuNPs) aqueous extract as a reducing and stabilizing agent. The obtained nanoparticles were then stabilized by another biocompatible agent, the chiral amino acids L-cysteine (L-Cys-AuNPs) and D-cysteine (D-Cys-AuNPs), to estimate the potential of the surface modification for enhancing AuNPs surface chemistry and antimicrobial action. The synthesized gold nanoparticles were confirmed by UV-Vis spectroscopy, FTIR, XRD, and circular dichroism to validate their formation, crystalline structure, surface properties, and chirality. Physicochemical characterization confirmed the formation of crystalline AuNPs with size and morphology modulated by chiral functionalization. TEM and DLS analyses showed that L-cysteine-functionalized AuNPs were smaller and more uniform, while FTIR and circular dichroism spectroscopy confirmed surface binding and the induction of optical activity, respectively. L-Cys-AuNPs exhibited the highest antimicrobial efficacy against a broad spectrum of microorganisms, including Escherichia coli, Salmonella enterica, Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, and, notably, Candida albicans. L-Cys-AuNPs showed the lowest MIC and MBC values, highlighting the synergistic effect of chirality on biological performance. These findings suggest that L-cysteine surface engineering significantly enhances the therapeutic potential of AuNPs, particularly in combating drug-resistant fungal pathogens such as C. albicans. This research paves the way for the development of next-generation antimicrobial agents, reinforcing the relevance of green nanotechnology in the field of materials science and nanotechnology. Full article

A key factor in calculating dairy cows’ nitrogen (N) excretion is knowing the amount of daily excreted urine. The present study aimed to investigate two methods to calculate the daily urine volume (UV) excreted using spot urine samples. Data were obtained from nine balance experiments involving 47 lactating and seven non-lactating German Holstein cows, with an average body weight (BW) of 620 ± 95 kg and an average age of 5.6 ± 1.4 years. Daily urinary creatinine (Cr) and UVs were known for all animals. The first method was developed by linearly regressing the daily excreted amount of Cr in urine against BW (p < 0.001; R² = 0.51; RSE: 2.8). The slope of the regression was used to calculate UV. The second method includes a non-linear regression of UV on Cr concentration in urine, allowing direct estimation of UV without knowledge of BW (p < 0.001; RSE: 8.13). Both estimation methods were compared to the standard method to determine UV from balance trials using Lin’s concordance correlation coefficient (CCC) and Bland–Altman plots. The first method had a CCC of 0.81, and the second method had a CCC of 0.85. Both methods can confidently be applied to calculate UV. Therefore, the second method is usable if BW is unavailable. Full article