Search Results (45)

This paper presents the optimization of storage conditions for textile dosimeters for ultraviolet radiation measurements, which are based on cotton-woven fabric and nitroblue tetrazolium chloride (NBT) as a radiation-sensitive compound. The results of changes in light reflectance and color coordinates depending on the storage time of the samples over six months from their manufacturing under various storage conditions are presented. The results obtained for cotton—NBT dosimeters, unirradiated and irradiated with a UVC dose of 100 mJ/cm², stored under the following conditions were compared: (i) at room temperature (23–25 °C, humidity 40–60%), without access to light; (ii) in a fridge (3–5 °C, humidity 70–90%), without access to light; (iii) in a freezer (−17 to −20 °C, humidity 80–90%), without access to light; and (iv) at room temperature (23–25 °C, humidity 40–60%), with access to light. Additionally, it was presented that the cotton–NBT dosimeters were suitable for 2D measurement of UV radiation doses after a period of eight months. The obtained results complement previous studies on cotton–NBT textile dosimeters and are crucial for determining the conditions of use and the expiry date of such systems. Full article

Clostridioides difficile (CD) is a Gram-positive, spore-forming anaerobic bacterium, usually transmitted through the fecal–oral route, that can result from direct person-to-person contact, exposure to contaminated environmental surfaces, or contact with the hands of colonized healthcare personnel. An increased number of infections, especially healthcare-associated, with this etiology has been observed in most countries. As a spore-forming organism, CD is resistant to alcohol formulations and is a challenge for chemical disinfection. The solution could be the supplementation of traditional disinfection with non-touch techniques, such as UV-C radiation. The adoption of UV-C as a supplementary disinfection method in hospitals has significantly increased since the COVID-19 pandemic. However, there are no current guidelines concerning the use of UV-C disinfection in hospitals. The aim of this study was to evaluate the effectiveness of UV-C irradiation in inactivating Clostridioides difficile from different types of surfaces in hospital settings. The study was based on laboratory tests evaluating the efficacy in eliminating three different C. difficile strains on carriers made of plastic, metal and glass after 10 min exposure to UV-C (wavelength, 253.7 nm). We observed a wide range of reductions in the C. difficile suspensions depending on the density of the carrier contamination, type of carrier, strains and the location of the carrier. The percentage reductions ranged from 0 to 100%, but the best results were observed for glass, with lower initial suspension density and carrier placement on a door frame. Statistically significant differences were only seen in different suspension densities. Our experiment was a continuation of the tests done for non-sporing bacteria and C. auris, and there were some interesting differences in C. difficile reflecting its biology, especially its sensitivity to an aerobic atmosphere during the sample drying. Although the elimination of C. difficile by UV-C radiation was confirmed in our experiment, it was lower than in the case of non-spore-forming bacteria. Thus, this method may be used in healthcare settings (hospitals) for improving environmental safety and preventing C. difficile spreading. Full article

In this work, we present a low-cost, label-free cellulose-based paper SERS (Surface-Enhanced Raman Scattering) substrate for the sensitive detection of thiol compounds. Uniform silver nanoparticles (AgNPs) were synthesized on cellulose filter paper via in situ reduction of a silver precursor under UVC irradiation, achieving a high SERS enhancement factor of 8.5 × 10⁶. The Ag-cellulose substrate demonstrated reliable detection of benzenethiol, capturing its characteristic SERS signals with remarkable sensitivity. Quantitative analysis was enabled by adjusting exposure times for accurate calibration. Furthermore, Principal Component Analysis (PCA) was successfully employed to distinguish mixed samples of benzenethiol, hexanethiol, and propanethiol, showcasing the substrate’s capability in separating complex mixtures. This cellulose-based AgNP platform offers a sustainable, cost-effective solution for rapid chemical detection, with significant potential for real-world applications such as environmental monitoring and food safety. Full article

Background and Objectives: The cornea protects the eye from external influences and contributes to its refractive power. Corneas belong to the most frequently transplanted tissues, providing a last resort for preserving the patient’s vision. There is a high demand for donor corneas worldwide, but almost 4% of these transplants are not eligible due to microbial contamination. The objective of this study is to ascertain the suitability of 222 nm Far-UVC irradiation for the decontamination of corneas without damaging corneal endothelial cells. Materials and Methods: To assess the destructive effect of irradiation and, thus, identify the applicable dose needed to decontaminate the cornea without interfering with its integrity, 141 porcine corneas were irradiated with 0, 60 or 150 mJ/cm² at 222 nm. In the second step, a series of 13 human corneas were subjected to half-sided irradiation using 15 or 60 mJ/cm² at 222 nm. After five days of in vitro culturing, the endothelial cell density of the non-irradiated area of each human cornea was compared to the irradiated area. Results: Irradiation with up to 60 mJ/cm² had no detectably significant effect on the cell integrity of human corneas (p = 0.764), with only a minimal reduction in cell density of 3.7% observed. These findings were partially corroborated by tests on porcine corneas, wherein the variability between test groups was consistent, even at increased irradiation doses of up to 150 mJ/cm², and no notable effects on the irradiated porcine endothelium were monitored. The efficacy of the antimicrobial treatment was evident in the disinfection tests conducted on corneas. Conclusions: These initial irradiation experiments demonstrated that 222 nm Far-UVC radiation has the potential to decontaminate the cornea without compromising sensitive endothelial cell viability. Full article

This study presents a novel surface acoustic wave (SAW)-based solar-blind ultraviolet-C (UV-C) corona sensor, marking the first reported use of HfO₂ as a sensing material for UV-C corona sensing. A 222 MHz two-port SAW delay line structure was selected as a sensor platform, and its optimal parameters were determined through Coupling of Mode (COM) modeling analysis. COMSOL simulations were conducted to investigate the effect of UV-C exposure on the HfO₂ thin film, highlighting its contribution to conductivity changes. A 30 nm-thick HfO₂ thin film was deposited using atomic layer deposition (ALD) within the cavity of a two-port SAW delay line, providing sufficient volume and density of absorption sites for UV-C exposure. Comprehensive material characterization of the HfO₂ thin film was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The effect of annealing temperature was analyzed in detail, with results confirming that 500 °C is the optimal temperature for achieving the best performance in a SAW-based UV-C corona sensor. The sensor characteristics were measured using custom-made interface electronics, allowing frequency shifts to be visually observed on a PC monitor with compensation for environmental factors such as humidity and temperature. The developed sensor demonstrated response and recovery times of 2.8 s and 4 s, respectively, with a measured sensitivity of 563 ppm/(mW·cm⁻²). Furthermore, the effect of HfO₂ film thickness on the sensor’s response to UV-C exposure was examined in detail, showing that increased thickness leads to a higher frequency shift, thereby enhancing sensitivity. The feasibility of the sensor for real-world applications was validated through successful testing under simulated corona discharge detection. Full article

Background: Energy delivered at different wavelengths causes different types of damage to DNA. Methods: PC-3, FaDu, 4T1 and B16-F10 cells were irradiated with different wavelengths of ultraviolet light (UVA/UVC) and ionizing radiation (X-ray). Furthermore, different photosensitizers (ortho-iodo-Hoechst33258/psoralen/trioxsalen) were tested for their amplifying effect. Survival fraction and damage analysis using the $\mathrm{\gamma }$H2A.X assay (double-strand breaks) and the ELISA assay (cyclobutane pyrimidine dimers) were compared. Results: The PC-3 cells were found to be the most sensitive cells to the treatment strategies used. FaDu and PC-3 showed a strong sensitivity to UVA. Analysis of the damage showed that the cell lines exhibited different sensitivities. Conclusions: Thus, an enhancing effect of photosensitizers (PS) in combination with UVA could be demonstrated in some cases. However, this is cell- and dose-dependent. Full article

Background/Objectives: This study identified early neonatal factors predicting pre-discharge mortality among extremely preterm infants (EPIs) or extremely low birth weight infants (ELBWIs) in China, where data are scarce. Methods: We conducted a retrospective analysis of 211 (92 deaths) neonates born <28 weeks of gestation or with a birth weight <1000 g, admitted to University Affiliated Hospitals from 2013 to 2024 in Guangzhou, China. Data on 26 neonatal factors before the first 24 h of life and pre-discharge mortality were collected. LASSO–Cox regression was employed to screen predictive factors, followed by stepwise Cox regression to develop the final mortality prediction model. The model’s performance was evaluated using the area under the curve (AUC) of the receiver operating characteristic, calibration curves, and decision curve analysis. Results: The LASSO–Cox model identified 13 predictors that showed strong predictive accuracy (AUC: 0.806/0.864 in the training/validation sets), with sensitivity and specificity rates above 70%. Among them, six predictors remained significant in the final stepwise Cox model and generated similar predictive accuracy (AUC: 0.830; 95% CI: 0.775–0.885). Besides the well-established predictors (e.g., gestational age, 5 min Apgar scores, and multiplicity), this study highlights the predictive value of the maximum FiO₂. It emphasizes the significance of the early use of additional doses of surfactant and umbilical vein catheterization (UVC) in reducing mortality. Conclusions: We identified six significant predictors for pre-discharge mortality. The findings highlighted the modifiable factors (FiO₂, surfactant, and UVC) as crucial neonatal factors for predicting mortality risk in EPIs or ELBWIs, and offer valuable guidance for early clinical management. Full article

Tunable blue/red dual-emitting Eu³⁺-doped, Bi³⁺-sensitized SrF₂ phosphors were synthesized utilizing a solvothermal-microwave method. All phosphors have cubic structure (Fm-3m (225) space group) and well-distinct sphere-like particles with a size of ~20 nm, as examined by X-ray diffraction and transmission electron microscopy. The diffuse reflectance spectra reveal a redshift of the absorption band in the UV region as the Bi³⁺ concentration in SrF₂: Eu³⁺ phosphor increases. Under the 265 nm excitation, photoluminescence spectra show emission at around 400 nm from the host matrix and characteristic orange ⁵D₀ → ⁷F_1,2 and deep red ⁵D₀ → ⁷F₄ Eu³⁺ emissions. The red emission intensity increases with an increase in Bi³⁺ concentration up to 20 mol%, after which it decreases. The integrated intensity of Eu³⁺ red emission in the representative 20 mol% Bi³⁺ co-doped SrF₂:10 mol% Eu³⁺ shows twice as bright emission compared to the Bi³⁺-free sample. To demonstrate the potential application in LEDs for artificial light-based plant factories, the powder with the highest emission intensity, SrF₂: 10Eu, 20 Bi, was mixed with a ceramic binder and placed on top of a 275 nm UVC LED chip, showing pinkish violet light corresponding to blue (409 nm) and red (592, 614, and 700 nm) phosphors’ emission. Full article

This work presents a 2D radiochromic dosimeter for ultraviolet (UV) radiation measurements, based on cotton fabric volume-modified with nitroblue tetrazolium chloride (NBT) as a radiation-sensitive compound. The developed dosimeter is flexible, which allows it to adapt to various shapes and show a color change from yellowish to purple-brown during irradiation. The intensity of the color change depends on the type of UV radiation and is the highest for UVC (253.7 nm). It has been shown that the developed dosimeters (i) can be used for UVC radiation dose measurements in the range of up to 10 J/cm²; (ii) can be measured in 2D using a flatbed scanner; and (iii) can have the obtained images after scanning be filtered with a medium filter to improve their quality by reducing noise from the fabric structure. The developed cotton–NBT dosimeters can measure UVC-absorbed radiation doses on objects of various shapes, and when combined with a dedicated computer software package and a data processing method, they form a comprehensive system for measuring dose distributions for objects with complex shapes. The developed system can also serve as a comprehensive method for assessing the quality and control of UV radiation sources used in various industrial processes. Full article

Effective disinfection processes have been investigated to provide pathogen-free drinking water. Due to growing concern about the potential negative effects of cyanobacteria in portable water, their treatment has gained more attention recently. This study aims to compare the inhibition efficiencies of Gram-negative bacteria (Escherichia coli; E. coli), Gram-positive bacteria (Bacillus subtilis; B. subtilis), and cyanobacteria (Microcystis aeruginosa; M. aeruginosa) using UV-C and solar irradiation, and their combination process with H₂O₂. Over 6 log removal value (LRV) of E. coli and B. subtilis was achieved within 1 min of UV-C irradiation (0.76 ± 0.02 mW/cm²). The solar and solar/H₂O₂ (50 mg/L) processes effectively reduced (>99%) both bacteria after 20 min. E. coli was more sensitive to hydroxyl radicals (•OH) compared to the B. subtilis due to a different cell wall structure, resulting in a 0.18–0.62 higher LRV than B. subtilis. However, solar-based processes did not effectively inhibit M. aeruginosa (>52.23%). The UV-C/H₂O₂ (50 mg/L) process showed the highest inhibition rate for M. aeruginosa (77.83%) due to the generation of •OH, leading to oxidative damage to cells. Additionally, chlorophyll-a (Chl-a) was measured to indicate cell lysis of M. aeruginosa. The removal rate of Chl-a extracted by viable M. aeruginosa was higher using the UV-C process (93.03%) rather than the UV-C/H₂O₂ process (80.95%), because UV-C irradiation could be most effective in damaging Chl-a. Full article

Biomaterials consist of both natural and synthetic components, such as polymers, tissues, living cells, metals, and ceramics. Their purpose is focused on repairing or replacing malfunctioning living tissues and organs. Therefore, it is imperative to ensure the safety and sterility of biomaterials before any contact with living tissue. Ultraviolet (UV)-C irradiation for biomaterial disinfection has been considered due to the high recurrence rate of bacterial infections and to prevent resistance. Physical composition and surface properties and UV-C sensitivity of microorganisms can alter its efficacy. The main objective of this study was to evaluate the efficacy of UV-C in terms of microbial lethality and additional underlying factors contributing to its performance, namely the surface properties. For this purpose, twelve different strains were first screened, from which four microorganism species known to have the ability to cause nosocomial infections were further tested, namely Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Candida glabrata. These microorganisms were inoculated onto slides and disks of various bio contact surfaces, including glass (GLS), titanium (Ti), and poly ether etherketone (PEEK), and exposed to UV-C. The results demonstrate that bacterial pathogens on biomaterial surfaces respond differently to UV-C light exposure, and the bactericidal effect decreased in this order: glass, PEEK, and Ti (0.5 to 2.0 log reduction differences). P. aeruginosa ATCC 27853 on glass surfaces was reduced to an undetectable level after being exposed to 6.31 J.cm⁻² of UV-C, displaying the highest reduction rate observed among all the tested microorganisms, 2.90 J⁻¹.cm⁻³, compared to Ti and PEEK. Similarly, a higher reduction in C. glabrata ATCC 2001 was observed on glass; the modeled inhibition displayed a rate of 1.30 J⁻¹.cm⁻³, the highest observed rate among yeast, compared to Ti and PEEK, displaying rates of 0.10 J⁻¹.cm⁻³ and 0.04 J⁻¹.cm⁻³, respectively. The inactivation rates were higher for less hydrophobic materials with smoother surfaces as compared to biomaterials with rougher surfaces. Full article

In this work, electrospun polylactide fibers with new photostabilizing additives, 4-methyl-2,6-diisobornylphenol (DIBP) and N-isocamphylaniline (NICA), have been tested under the influence of UV-C radiation (254 nm). The changes in the polymers’ chemical structure under UV-C radiation were revealed through the increase in absorption in the 3600–3100 cm⁻¹ region in regard to the FTIR spectra. In the samples that were irradiated for 1 h, the stabilizing effect of the photoprotectors became most noticeable as the difference in the content of the hydroxyl groups in stabilized and the pure PLA reached a maximum. The TG–DSC method revealed that the most sensitive indicator of the irradiation effect was the glass transition temperature (T_g), which persisted after 2 h of irradiation when using photostabilizers and their combinations. The PLA/DIBP(1) and PLA/NICA(1) samples showed the best results in protecting PLA from UV-C radiation based on the T_g values; although, the mixture of DIBP and NICA was not as effective. The chemical structure of the photostabilized PLA samples was studied using NMR, GPC, and Py–GC/MS analysis. The electrospun polylactide fibers were mechanically tested and the effects of the electrospun samples on cell viability were studied. Full article

Historically, the photocatalytic efficacy of graphitic carbon nitride (g-C₃N₄) has been constrained by a rapid charge recombination rate and restricted sensitivity to visible light. To overcome these limitations and enhance the performance of g-C₃N₄, the strategic formation of heterojunctions with semiconductor materials is deemed the optimal approach. The present study employed a facile sonication-assisted pyrolysis method to synthesize a g-C₃N₄@ZrO₂ nanocomposite photocatalyst. This hybrid material was characterized extensively using a comprehensive suite of analytical techniques, including XRD, SEM, EDX, FTIR, and UV-Vis DRS. A comparative analysis of photocatalytic applications under identical conditions was conducted for all synthesized materials, wherein they were subjected to UVc light irradiation. The photocatalytic degradation of various dye models, such as MB, EY, and a combination of dyes, was assessed using the prepared nanocomposites. The g-C₃N4@ZrO₂ photocatalysts showcased superior photocatalytic performance, with a particular variant, g-CNZ₆, exhibiting remarkable activity. With a bandgap energy of 2.57 eV, g-CNZ₆ achieved impressive degradation efficiencies of 96.5% for MB and 95.6% for EY within 40 min. Following previous studies, the superoxide radical anions (O₂⁻. and h⁺) were largely accountable for the degradation of MB. Therefore, the observed efficacy of the g-C₃N4@ZrO₂ nanocomposite photocatalyst can be attributed to the increased generation of these reactive species. Full article

Moringa oleifera has a high level of active chemicals that are useful in the food industry, and they have antibacterial and food preservation properties. The characterization of M. oleifera seed oil (MOS) may vary due to agronomic and environmental factors. Therefore, it was necessary to know the composition of lipids present in our oil extracted under pressing at 180 °C and thus determine if it is suitable to produce a biopackaging. Within the characterization of the oil, it was obtained that MOS presented high-quality fatty acids (71% oleic acid) with low values of acidity (0.71 mg KOH/g) and peroxide (1.74 meq O₂/kg). Furthermore, MOS was not very sensitive to lipoperoxidation by tert-butyl hydroperoxide (tBuOOH) and its phenolic components, oleic acid and tocopherols, allowed MOS to present a recovery of 70% after 30 min of treatment. Subsequently, a biopackaging was developed using a multiple emulsion containing corn starch/carboxymethylcellulose/glycerol/MOS, which presented good mechanical properties (strength and flexibility), transparency, and a barrier that prevents the transfer of UV light by 30% and UV-C by 98%, as well as a flux with the atmosphere of 5.12 × 10⁻⁸ g/ m.s. Pa that prevents moisture loss and protects the turkey ham from O₂. Hence, the turkey ham suffered less weight loss and less hardness due to its preservation in the biopackaging. Full article

Introduction: Healthcare-associated infections in the post-pandemic era are as important as they were before COVID-19. The dominant route of transmission of microorganisms in health care units is the contact route, for which hand hygiene is of cardinal importance, but also effective disinfection of touch surfaces. Traditional disinfection based on chemical compounds is sensitive to human errors. Therefore, a valuable supplement to it can be contactless disinfection methods, including the use of UV-C. The aim of the study was to assess the effectiveness of UV-C radiation in eliminating selected, most important pathogens of particular epidemic importance from surfaces made of various materials: stainless steel, plastic and glass, most often found in hospital conditions. Material and Method: In laboratory conditions, the study was conducted using bacterial strains of great epidemiological importance and Candida auris. In hospital wards, samples were taken before and after disinfection for comparisons of the composition and quantity of bacteria. In laboratory conditions, carriers made of steel, plastic and glass were contaminated with a bacterial suspension with a density of approx. 0.5 McFarland, and then the density of persistent microorganisms was assessed after 10 min of UV-C irradiation. Results: The high effectiveness of UV-C radiation in eliminating bacteria contaminating touch surfaces in hospital wards and in laboratory conditions has been confirmed. The elimination efficiency in laboratory conditions was slightly lower (statistically insignificant) on the plastic surface, which is probably related to subtle differences in the thickness of the contaminating layer. Hydrophobic properties and the smallest suspension diameter were confirmed for the tested plastic carriers. Conclusions: UV-C disinfection is a desirable element to support traditional, chemical methods of disinfection in hospital conditions, effective against multidrug-resistant bacteria and C. auris. Full article