Search Results (33)

This study explored advancements in photovoltaic technologies by enhancing the electronic quality of multicrystalline silicon (mc-Si) through silicon nitride (SiN_x) and hydrogen (H₂) plasma deposition via plasma-enhanced chemical vapor deposition (PECVD). This innovative approach replaced toxic chemical wet processes with H₂ plasma and SiN_x. The key parameters of silicon solar cells, including the effective lifetime (τ_eff), diffusion length (L_diff), and iron concentration ([Fe]), were analyzed before and after this sustainable solution. The results show significant improvements, particularly in the edge region, which initially exhibited a low τ_eff and a high iron concentration. After the treatment, the τ_eff and L_diff increased to 7 μs and 210 μm, respectively, compared to 2 μs and 70 μm for the untreated mc-Si. Additionally, the [Fe] decreased significantly after the process, dropping from 60 ppt to 10 ppt in most regions. Furthermore, the treatment led to a significant decrease in reflectivity, from 25% to 8% at a wavelength of 500 nm. These findings highlight the effectiveness of the PECVD-SiN_x and H₂ plasma treatments for improving the optoelectronic performance of mc-Si, making them promising options for high-efficiency photovoltaic devices. Full article

Objectives: A simple method for quantifying fluconazole in small blood volumes has been developed using volumetric absorptive microsampling (VAMS^®) technology and isocratic high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Methods: For sample collection, Mitra^® devices are used to keep the sample volume at 10 µL. For the quantitative determination of fluconazole, the Mitra^® samples are extracted using acetonitrile as the extraction agent, containing 2-(4-chlorophenyl)-1,3-bis(1,2,4-triazol-1-yl)propan-2-ol as the internal standard. A Synergi 4 μm Polar-RP 80 Å (150 × 2 mm) column forms the stationary phase, and a mixture of acetonitrile and phosphate buffer is the mobile phase. The UV detection is set at a wavelength of 210 nm. The therapeutic concentration range of 5 to 160 mg/L is covered, and the linear equation with 1/x² weighting is used to determine unknown samples. This method has been validated according to the current EMA and FDA guidelines for bioanalytical methods. Results: The validation data obtained after analysing whole blood samples (EDTA) showed within- and between-run accuracy between 94.4% and 115% and precision between 0.4% and 9.4%, respectively. A lower limit of quantification (LLOQ) of 5 mg/L was sufficient for therapeutic drug monitoring in paediatric patients receiving fluconazole as antifungal prophylaxis after haematopoietic cell transplantation. Conclusions: So far, 211 samples from 49 patients were successfully analysed, and concentrations between 5.84 mg/L and 107 mg/L were determined for whole blood Mitra^® samples. To our knowledge, this is the first application of VAMS^® technology using simple and cheap HPLC-UV quantification. Full article

In this paper, methods for the determination of clopidogrel bisulphate and metamizole sodium in rinse waters from industrial equipment, using multiwavelength UV spectrometry and the calculation of areas under curves, are proposed. Spectra were recorded in an aqueous medium without preliminary pH adjustment. A numerical integration of the spectra was performed in the wavelength range of 210 to 290 nm for clopidogrel bisulphate, and 220 to 320 nm for metamizole sodium. The methods enable the determination of clopidogrel bisulphate and metamizole sodium in solution in the concentration range of 1–100 mg/L, do not require lengthy sample preparation and complex analytical equipment, and are suitable for the routine determination of these drugs in rinse waters from industrial equipment. Full article

Gallium oxide (Ga₂O₃) has gained considerable attention due to its wide bandgap, the availability of native substrates, and its excellent properties for solar-blind photodetectors, transparent electronics, and next-generation power devices. However, the expensive Ga₂O₃ native substrates have restricted its widespread adoption. To reduce costs and further the development of β-Ga₂O₃-based devices, there is a need for bandgap-tunable oxide films with high crystal quality for deep-ultraviolet (DUV) photodetectors and high-breakdown-field power devices. This study introduces a Thermal Interdiffusion Alloying method to address these requirements. It focuses on developing deep ultraviolet (DUV) photodetectors using β-Ga₂O₃ thin films on sapphire substrates by promoting the diffusion of aluminum (Al) atoms from the substrate into the film, resulting in the formation of aluminum gallium oxide (β-(Al_xGa_1−x)₂O₃). The aluminum content is controlled by adjusting the process temperature, allowing for tunable detection wavelengths and enhanced DUV sensing capabilities. Radio frequency (RF) sputtering optimizes the film’s quality by adjusting the sputtering power and the argon/oxygen (Ar/O₂) flow ratio. Material analysis indicates that this method expands the optical bandgap and shifts the response wavelength to 210 nm, significantly boosting the performance of the fabricated photodetectors. This research presents considerable potential for advancing DUV photodetectors across various disinfection applications. Full article

The impact of fluorine on plants remains poorly understood. We examined duckweed growth in extracts of soil contaminated with fluorine leached from chicken manure. Additionally, fluorine levels were analyzed in fresh manure, outdoor-stored manure, and soil samples at varying distances from the manure pile. Fresh manure contained 37–48 mg F⁻ × kg⁻¹, while soil extracts contained 2.1 to 4.9 mg F⁻ × kg⁻¹. We evaluated the physiological effects of fluorine on duckweed cultured on soil extracts or in 50% Murashige–Skoog (MS) medium supplemented with fluorine concentrations matching those in soil samples (2.1 to 4.9 mg F⁻ × L⁻¹), as well as at 0, 4, and 210 mg × L⁻¹. Duckweed exposed to fluorine displayed similar toxicity symptoms whether in soil extracts or supplemented medium. Fluoride at concentrations of 2.1 to 4.9 mg F⁻ × L⁻¹ reduced the intact chlorophyll content, binding the porphyrin ring at position 3² without affecting Mg²⁺. This reaction resulted in chlorophyll a absorption peak shifted towards shorter wavelengths and formation of a new band of the F⁻-chlorophyll a complex at λ = 421 nm. Moreover, plants exposed to low concentrations of fluorine exhibited increased activities of aminolevulinic acid dehydratase and chlorophyllase, whereas the activities of both enzymes sharply declined when the fluoride concentration exceeded 4.9 mg × L⁻¹. Consequently, fluorine damages chlorophyll a, disrupts the activity of chlorophyll-metabolizing enzymes, and diminishes the plant growth rate, even when the effects of these disruptions are too subtle to be discerned by the naked human eye. Full article

This study aims to assess the contents of different kinds of low-molecular-weight organic acids (LMWOAs) in reclaimed soil filled with fly ash in the Huainan mining area in China using high-performance liquid chromatography (HPLC). Using a mobile phase consisting of 0.1% phosphoric acid and acetonitrile in a volume ratio of 98:2, the detection was performed at a wavelength of 210 nm for 15 min. In addition, a cluster analysis was performed on the detected LMWOAs in the reclaimed soil. The correlations between the LMWOA and nutrient contents in the reclaimed soil were also analyzed. In total, eight and seven LMWOAs were detected in the reclaimed soil and filled fly ash, respectively. In contrast, no LMWOAs were detected in the fresh fly ash from a thermal power plant. The order of total LMWOA contents at different sampling points followed the order of farmland control soil > 1# (Triticum aestivum) > 4# (Phragmites australis) > 5# (Vigna radiata) > 2# (Sorghum bicolor) > 3# (Tamarix ramosissima) > fly ash-filled soil. The farmland control soil and fly ash-filled soil exhibited the highest and lowest LMWOA contents of 648.22 and 85.09 μg·g⁻¹, respectively. The LMWOA contents in the reclaimed soil followed the order of oxalic acid > tartaric acid > malonic acid > lactic acid > acetic acid > citric acid > propionic acid > succinic acid. Indeed, oxalic acids exhibited the highest total amount of 1445.79 μg·g⁻¹ and succinic acids exhibited the lowest total amount of 6.50 μg·g⁻¹. The LMWOA contents in the reclaimed soil decreased with increasing soil depth, showing statistically significant differences between the 0–10 and 10–40 cm soil layers (p < 0.05). According to the obtained clustering results, the detected LMWOAs can be divided into two categories. The first category consisted of oxalic acid, while the second category included the remaining LMWOAs. The soil LMWOA contents of 4# (Phragmites australis) and 5# (Vigna radiata) were significantly different from those at the other sampling points. According to the Pearson correlation analysis results, the occurrence and characteristics of the soil LMWOAs can be controlled by regulating the pH values and available nutrient contents in the soil, thereby improving the eco-environmental conditions of the reclaimed rhizosphere. Full article

Ginkgo biloba leaves (GBLs), which comprise many phytoconstituents, also contain a toxic substance named ginkgolic acid (GA). Our previous research showed that heating could decarboxylate and degrade GA into ginkgols with high levels of bioactivity. Several methods are available to measure GA in GBLs, but no analytical method has been developed to measure ginkgols and GA simultaneously. Hence, for the first time, an HPLC-DAD method was established to simultaneously determine GA and ginkgols using acetonitrile (0.01% trifluoroacetic acid, v/v) as mobile phase A and water (0.01% trifluoroacetic acid, v/v) as mobile phase B. The gradient elution conditions were: 0–30 min, 75–90% phase A; 30–35 min, 90–90% phase A; 35–36 min, 90–75% phase A; 36–46 min, 75–75% phase A. The detection wavelength of GA and ginkgol were 210 and 270 nm, respectively. The flow rate and injection volume were 1.0 mL/min and 50 μL, respectively. The linearity was excellent (R² > 0.999), and the RSD of the precision, stability, and repeatability of the total ginkgols was 0.20%, 2.21%, and 2.45%, respectively, in six parallel determinations. The recoveries for the low, medium, and high groups were 96.58%, 97.67%, and 101.52%, respectively. The limit of detection of ginkgol C13:0, C15:1, and C17:1 was 0.61 ppm, 0.50 ppm, and 0.06 ppm, respectively. The limit of quantification of ginkgol C13:0, C15:1, and C17:1 was 2.01 ppm, 1.65 ppm, and 0.20 ppm, respectively. Finally, this method accurately measured the GA and ginkgol content in ginkgo leaves and ginkgo tea products (ginkgo black tea, ginkgo dark tea, ginkgo white tea, and ginkgo green tea), whereas principal component analysis (PCA) was performed to help visualize the association between GA and ginkgols and five different processing methods for GBLs. Thus, this research provides an efficient and accurate quantitative method for the subsequent detection of GA and ginkgols in ginkgo tea. Full article

One of the key indicators of water quality is dissolved oxygen. Even though oxygen is important in environmental monitoring, the sensors for dissolved oxygen are expensive and require periodic maintenance due to the use of membranes. In this paper, we propose using ultraviolet light absorption to estimate dissolved oxygen saturation in water samples. The absorption spectrum of dissolved oxygen in the ultraviolet range is investigated over a water matrix with different levels of complexity. First, the difference between different water matrixes is studied. The results indicate similar variations between river water and tap water matrices for comparative purposes. Both samples present much higher absorbance signals than distilled water. Thus, the rest of the tests were performed with only three water matrixes (ultrapure, distilled, and river water). By aerating, water samples were completely saturated. Then, nitrogen gas was used to remove dissolved oxygen from samples to obtain saturations of 75, 50, 25, and 3%. The absorption was measured from 190 to 380 nm, using LLG-uniSPEC 2. The obtained data were used to generate regression models for selected wavelengths (190, 210, 240, and 250 nm). The differences beyond 260 nm for the studied dissolved oxygen saturations were null. The generated models had correlation coefficients from 0.99 to 0.97 for ultrapure water, 0.98 to 0.95 for distilled water, and 0.90 to 0.83 for river water. The maximum differences were found between samples with 75 and 100% of saturation. Full article

In this work, solid-state reaction sintering was used to fabricate Ca₇ZrAl₆O₁₈-Ca₃Al₂O₆-CaZrO₃:Eu³⁺ ternary composite ceramics and cements. The structural, microstructural, and spectroscopic properties of the ceramics with different Eu₂O₃ content were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), and spectrofluorimetry, respectively. The XRD patterns analyzed with Rietveld refinement confirm the presence of the orthorhombic phase of Ca₇ZrAl₆O₁₈ and the cubic phase of Ca₃Al₂O₆ in all the samples, indicating that doping of Eu³⁺ slightly changes the crystalline structure of both aluminate phosphors. EDS analysis revealed that the Eu doping element was strongly concentrated to the two phases, i.e., Ca₇ZrAl₆O₁₈ and Ca₃Al₂O₆, with the Eu concentrations of 8.45 wt.% and 8.26 wt.%, respectively. The luminescent properties of the ceramics doped with different Eu³⁺ ion concentrations were investigated by excitation and emission spectroscopy at room temperature. These results were compiled using a laser with an optical parametric oscillator (OPO) system. The obtained spectra indicated changes in the luminescence intensity and shape occurring with phase composition and Eu₂O₃ concentration. The emission spectra of the ceramics exhibit a strong dependence on the excitation wavelength in the range from 210 to 300 nm, and invariably, five peaks were assigned to the ⁵D₀ → ⁷F_J (J = 0, 1, 2, 3, 4) transitions of Eu³⁺. The luminescence spectroscopy was then used to trace the early and long-term hydration behavior of cements. Thus, luminescence spectroscopy may provide a new tool for non-destructive testing of cement-based structures. Full article

The presence of synthetic industrial dyes in the environment poses significant risks to aquatic ecosystems, human health, and economies. This study aims to synthesize iron oxide nanoparticles (IONPs) using a green method, analyze them using physicochemical techniques, and examine the effectiveness with which they photocatalytically degrade crystal violet dye in sunlight. Fourier transform infrared spectroscopy (FTIR) analysis revealed that the biogenic IONPs showed a UV peak at a wavelength of 241 nm, with functional groups including phenols, alkynes, and alkenes. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the bioinspired IONPs. The mean diameter of the biogenic IONPs was 49.63 ± 9.23 nm, and they had a surface charge of −5.69 mV. The efficiency with which the synthesized IONPs removed the crystal violet dye was evaluated under dark and sunlight conditions. The removal efficiency was found to be concentration and time dependent, with a peak removal percentage of 99.23% being achieved when the IONPs were exposed to sunlight for 210 min. The biogenic IONPs also demonstrated antioxidant activity, with a relative IC₅₀ value of 64.31 µg/mL. In conclusion, biogenic IONPs offer a viable and environmentally friendly approach for eradicating industrial synthetic dyes and remediating contaminated environments and aquatic ecosystems. Full article

Background: To examine the 12-month clinical and refractive outcomes of PRK performed with a UV all-solid-state laser. Methods: The study included healthy patients with myopia and/or compound myopic astigmatism enrolled for refractive surgery and treated with PRK using a 210 nm wavelength, 2 kHz repetition rate, UV all-solid-state laser (LaserSoft, Katana Technologies GmbH, Kleinmachnow, Germany). All subjects were examined at baseline and after 1, 3, 6, and 12 months after the treatment with a slit lamp, refraction, visual acuity assessment (logMAR chart), tonometry, ophthalmoscopy, and corneal tomography with a Scheimpflug camera. The outcome measures considered were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, central corneal thickness, and transparency. The efficacy, safety, predictability, and stability were determined. Results: The study included 34 eyes of 19 patients. The mean UDVA changed from 1.20 ± 0.43 to −0.05 ± 0.10 logMAR at 12 months, and the mean CDVA changed from −0.03 ± 0.06 to −0.06 ± 0.09 logMAR, respectively. The mean spherical equivalent (SE) changed from −4.90 ± 2.12 D to −0.01 ± 0.40 D and was within ±0.50 D of the intended correction in 91% of eyes and within ±1.00 D in 97% of eyes at 12 months. No eyes lost lines of visual acuity, and 64% of eyes gained one or more lines. Conclusions: PRK with the 210 nm wavelength, 2 kHz repetition rate, all-solid-state laser LaserSoft system proved to have good visual, refractive, and clinical outcomes after the follow-up at 12 months. The emerging gas-free, solid-state technology might be considered a valid alternative for the gas operating lasers for corneal refractive surgery. Full article

In this paper, we demonstrate a high-power, quasi-continuous wave using a laser-diode dual-end-pumped Nd:YAG InnoSlab laser at 1319 nm. The maximum average output power of 210 W at a single 1319 nm wavelength is obtained with an optical-optical efficiency of 18.8% from absorbed pump power to laser output. The output pulse duration is 246 μs at the repetition of 500 Hz, and the beam quality factors of M² are 1.37 and 1.47 in the horizontal and vertical directions, respectively. This is the first report on high-power, quasi-continuous wave using Nd:YAG InnoSlab lasers at 1319 nm with good beam quality. Full article

A capillary zone electrophoretic (CZE) method was developed, validated, and applied for the assay of metformin (MET) and pioglitazone (PIO) in pharmaceutical formulations. The optimum running buffer composition was found to be 75 mmol/L phosphate buffer containing 30% acetonitrile (ACN) at pH 4.0. The optimum instrumental conditions were found to be injection time, 10 s; applied voltage, 25 kV; hydrodynamic injection pressure, 0.5 psi for 10 s, capillary temperature, 25 °C; and the detection wavelength, 210 nm. The quantifications were calculated based on the ratio of the peak areas of analytes to atenolol as an internal standard. The CZE method was validated in terms of accuracy (98.21–104.81%), intra- and inter-day precision of migration time and peak area (relative standard deviation ≤ 5%), linearity (correlation coefficients ≥ 0.9985), limit of detection (≤0.277 μg/mL), and limit of quantitation (≤0.315 μg/mL). The proposed method was applied for the analysis of PIO and MET both individually and in a combined dosage tablet formulation. All electrophoretic parameters were calculated and evaluated. A previously reported high-performance liquid chromatographic (HPLC) method was also applied to the same samples. A comprehensive comparison was then carried out for the analytical features of both methods CZE and HPLC. Comparable results were obtained with the advantage of reagent consumption and separation efficiency of CZE over HPLC and shorter analysis time by HPLC compared with CZE. Full article

In this paper, physicochemical properties of pure Y₂O₃ and samarium (Sm)-doped Y₂O₃ transparent ceramics obtained via arc plasma melting are presented. Yttria powder with a selected molar fraction of Sm was first synthesized by a solid-state reaction method. High transparent yttria ceramics were obtained by arc plasma melting from both the pure and Sm oxide-doped powders. The morphological, chemical and physical properties were investigated by X-ray diffraction and scanning electron microscopy. The optical band gap was calculated from the absorption spectra so as to understand the electronic band structure of the studied materials. Samples indicate a series of luminescence bands in the visible region after excitation by laser light in the range from 210 to 250 nm. Magneto-optical measurements were carried out in the 300–800 nm range at room temperature. It can be seen that a maximum Verdet constant ca. 24.81 deg/T cm was observed for 405 nm and this value decreases with increasing wavelength. The potential usefulness of the polycrystalline material dedicated to optics devices is presented. Full article

The UV-Vis absorption, fluorescence, and phosphorescence spectra of poly(3,4-ethylenedioxythiophene/cucurbit[7]uril), polypseudorotaxane (1), and polyrotaxane (2) in water and acetonitrile solutions were investigated. To achieve a deeper insight into the optical properties, the transient absorptions, lifetimes, and quantum yields have been carried out on compounds 1 and 2. The transient absorption demonstrated an excited-state processes and involvement of high energy electronic states (S_n > 1). The transient absorption map in acetonitrile revealed at 210, 240, 300, and 315 nm a ground states bleaching bands (GSB), whereas at shorter wavelengths an absorption in excited states (ESA) and more than one excited state (S_n > 1). At 382 and 420 nm wavelength two negative bands appeared which were assigned to the stimulated emissions (SE). At longer wavelengths, i.e., 605, 625, and 710 nm, other stimulated emissions appeared that are probably a result of the triplet manifold, confirming their phosphorescence properties. Additionally, the quantum yield with absolute values in the range 5–25%, and phosphorescence lifetime with values in the range 1–9 μs were evaluated. Full article