Search Results (688)

The increasing prevalence of common cold viruses and bacteria in daily life has heightened interest in sterilization lamp technologies. Compared with traditional mercury-based ultraviolet (UV) lamps, modern UV lamps offer advantages including extended operational lifespan, high energy efficiency, compact form factor, and the absence of hazardous materials, rendering them both safer and environmentally sustainable. In particular, UV-C LED lamps, which emit at short wavelengths, are capable of disrupting the molecular structure of DNA or RNA in microbial cells, thereby inhibiting cellular replication and achieving effective disinfection and sterilization. Conventional UV-C LED sterilization lamp driver circuits frequently employ a two-stage architecture, which requires a large number of components, occupies substantial physical space, and exhibits reduced efficiency due to multiple stages of power conversion. To address these limitations, this paper proposes a UV-C LED sterilization lamp driver circuit for an AC voltage supply, employing boundary conduction mode (BCM) control with integrated power factor correction (PFC). The proposed single-stage, single-switch topology combines a buck PFC converter and a flyback converter while recovering transformer leakage energy to further improve efficiency. Compared with conventional two-stage designs, the proposed circuit reduces the number of power switches and components, thereby lowering manufacturing cost and enhancing overall energy conversion efficiency. The operating principles of the proposed driver circuit are analyzed, and a prototype is developed for a 110 V AC input with an output specification of 10.8 W (90 V/0.12 A). Experimental results demonstrate that the prototype achieves an efficiency exceeding 92%, a power factor of 0.91, an output voltage ripple of 1.298%, and an output current ripple of 4.44%. Full article

Volatile organic compounds (VOCs) are major contributors to air pollution, posing significant environmental and health risks. Here we report gallium oxide (Ga₂O₃)-coated mesh as a practical immobilized photocatalyst for VOC degradation under UVC irradiation. A 3 wt.% Ga₂O₃ suspension was spray-coated onto the stainless-steel mesh, yielding a uniform coating with strong adhesion properties, as confirmed by cross-sectional analysis. Under identical conditions to a Ga₂O₃ powder, the Ga₂O₃-coated mesh delivered comparable VOC degradation rates and first-order kinetics while offering superior mechanical stability and ease of handling. Over five consecutive cycles, 93–95% of the VOC degradation efficiency was retained with negligible loss of activity, confirming excellent reusability. Fourier Transform Infrared Spectroscopy (FTIR) spectra of the Ga₂O₃-coated mesh after degradation reaction revealed significantly reduced VOC peaks, such as C=O and C-O absorption peaks, whereas spectra for the uncoated mesh changed only slightly. These results indicate that VOC degradation originates from the coated photocatalyst. Overall, these findings demonstrate that Ga₂O₃-coated mesh is a highly efficient, stable, and reusable platform for VOC removal, suggesting its potential for practical applications in air purification and environmental remediation. Full article

UV-C radiation has emerged as a germicidal agent against pathogens, particularly following the COVID-19 pandemic. While UV-C effectively reduces cross-contamination in hospitals, it induces photodegradation in polymer devices, potentially damaging and posing risks to patient safety. Therefore, it is crucial to detect the effects of UV-C photodegradation on early stages, as well as the effects of prolonged UV-C exposure. In this study, we investigated the UV-C photodegradation (254 nm, 471 kJ/mol) of isotactic polypropylene homopolymer (PP), commonly used in medication packaging. The impact of UV-C on PP was evaluated through rheology and infrared spectroscopy. Surface energy was measured by the contact angles formed by drops of water and diiodomethane. The effects of photodegradation on the polymer’s morphology were examined using scanning electron microscopy, and the melting temperature and crystallinity by differential scanning calorimetry. Lastly, the effect of UV-C on molecular mobility was studied using ¹H Time Domain Nuclear Magnetic Resonance (¹H TD-NMR). These techniques proved to be valuable tools for identifying the early stages of UV-C photodegradation, and ¹H TD-NMR was a sensitive method to identify the chain branching as a photodegradation product. This study highlights the impact of UV-C on PP photodegradation and hence the importance of understanding UV-C-induced degradation. Full article

The fluorescence of aqueous solutions of the aromatic amino acids tryptophan, tyrosine, and phenylalanine, an albumin solution, and a mixture of water-soluble animal and plant proteins is investigated after treatment with hydroxyl and hydroperoxyl radicals and continuous UV-C radiation at λ = 253.7 nm. The use of independent sources of active species allows for the study of activation and the development of free radical processes in model objects. The analysis is based on Stern–Volmer coefficients for the quenching of the fluorescence of the initial substrates and the ignition of the fluorescence of newly formed products. In the reaction with hydroxyl radicals, the hydrogen atom could be abstracted from any position in the target molecule. Under continuous UV-C radiation, the protein molecule as a whole was excited. Full article

Sindbis virus (SINV) is a mosquito-borne alphavirus capable of causing neurological and immunological symptoms in humans, yet its effects on neural/immune systems remain insufficiently characterized. This study aimed to examine SINV replication, UV-C light inactivation, apoptosis induction, and immune gene modulation in human SH-SY5Y neuroblastoma cells. Following viral adaptation and infectious dose determination, SINV replication and inactivation were assessed using RT-qPCR and dsRNA immunofluorescence. Apoptotic markers (caspase-3, Bax, Bcl-2) were analyzed by immunofluorescence and immune genes expression kinetics (TLR3/7, RIGI, MDA5, IL-1β, IL-6, TNFα, IL-10, IFNβ and β-catenin) were measured at defined time points post-infection by RT-qPCR. SH-SY5Y cells supported productive SINV infection, with viral RNA detectable as early as 3 hpi and marked cytopathic effects by 24 hpi. A custom-built UV-C chamber achieved complete viral inactivation following 3 × 30 s exposures. We observed SINV time-course replication and UV-C inactivation with conspicuous morphological alterations in SH-SY5Y cells. Furthermore, SINV triggered caspase-dependent apoptosis and robust transcriptional upregulation of innate immune genes, peaking between 12–16 hpi and declining by 30 hpi. These findings elucidate the temporal dynamics of SINV replication, cell death mechanisms, and immune activation in a neuronal context, contributing to a better understanding of SINV neuropathogenesis. Full article

This study presents the development and evaluation of an automated ultraviolet-C irradiation system for maize seed treatment, emphasizing disinfection performance, environmental control, and vision-based monitoring. The system features dual 8-watt ultraviolet-C lamps, sensors for temperature and humidity, and an air extraction unit to regulate the microclimate of the chamber. Without air extraction, radiation stabilized within one minute, with internal temperatures increasing by 5.1 °C and humidity decreasing by 13.26% over 10 min. When activated, the extractor reduced heat build-up by 1.4 °C, minimized humidity fluctuations (4.6%), and removed odors, although it also attenuated the intensity of ultraviolet-C by up to 19.59%. A 10 min ultraviolet-C treatment significantly reduced the fungal infestation in maize seeds by 23.5–26.25% under both extraction conditions. Thermal imaging confirmed localized heating on seed surfaces, which stressed the importance of temperature regulation during exposure. Notable color changes ($\Delta E>2.3$) in treated seeds suggested radiation-induced pigment degradation. Ultraviolet-C intensity mapping revealed spatial non-uniformity, with measurements limited to a central axis, indicating the need for comprehensive spatial analysis. The integrated computer vision system successfully detected seed contours and color changes under high-contrast conditions, but underperformed under low-light or uneven illumination. These limitations highlight the need for improved image processing and consistent lighting to ensure accurate monitoring. Overall, the chamber shows strong potential as a non-chemical seed disinfection tool. Future research will focus on improving radiation uniformity, assessing effects on germination and plant growth, and advancing system calibration, safety mechanisms, and remote control capabilities. Full article

The harsh conditions of the space environment necessitate advanced materials capable of withstanding extreme temperature fluctuations and ultraviolet (UV) radiation. While epoxy-based composites are widely utilized in aerospace due to their favorable strength-to-weight ratio, they are prone to degradation, especially under prolonged high-energy UV-C exposure. This study investigated the mechanical and chemical stability of epoxy composites reinforced with nanosilica at 0, 2, 5, and 10 wt% before and after UV-C irradiation. Dynamic mechanical analysis (DMA) revealed that increased nanosilica content enhanced the storage modulus below the glass transition temperature (Tg) but reduced both Tg and the damping factor. Following UV-C exposure, all samples showed a decrease in storage modulus and Tg; however, composites with higher nanosilica content maintained better property retention. Frequency sweeps corroborated these findings, indicating improved instantaneous modulus but accelerated relaxation with increased nanosilica. Fourier-transform infrared (FTIR) spectroscopy of UV-C-exposed samples demonstrated significant oxidation and carboxylic group formation in neat epoxy, contrasting with minimal spectral changes in nanosilica-modified composites, signifying improved chemical resistance. Overall, nanosilica incorporation substantially enhances the thermomechanical and oxidative stability of epoxy composites under simulated space conditions, highlighting their potential for more durable performance in low Earth orbit applications. Full article

Volatile organic compounds (VOCs), including benzene, toluene, and formaldehyde, are hazardous air pollutants that require efficient and sustainable mitigation strategies. Photocatalytic degradation of VOCs offers a promising pathway; however, its performance is strongly influenced by multiple operational parameters. Here, we present a systematic investigation of toluene degradation under ultraviolet-C (UVC) irradiation across controlled temperatures using Ga₂O₃ as a photocatalyst. A comprehensive analysis revealed that elevated temperatures enhanced photocatalytic activity by accelerating chemical reaction rates. However, further temperature increases led to a decrease in performance due to a reduction in the reactant adsorption rate. An optimal operating temperature was identified, at which the balance between chemical reaction rates and reactant adsorption yields the highest degradation efficiency. These findings demonstrate Ga₂O₃ as a promising photocatalyst and provide fundamental insights into the temperature-dependent photocatalytic mechanisms governing VOC removal in practical environmental applications. Full article

This study investigated the microbiological, physicochemical, textural, and sensory characteristics of ayran and kefir samples produced from milk treated with different doses of UV-C radiation. For this purpose, raw milk was passed through a UV-C column at three different flow rates (15, 30, and 45 mL/min), and irradiated with doses of 72, 36, and 24 J/mL, respectively, corresponding to the flow rate. Samples produced from milk pasteurised by thermal treatment were used as the control group. This research indicated that UV-C treatment effectively reduced the microbial load in milk to a level comparable to that achieved through conventional pasteurisation. A reduction of 2.15 log cfu/mL in total aerobic mesophilic bacteria count was achieved, while total coliform group bacteria counts were decreased to an undetectable level. Samples produced from milk treated with UV-C showed lower pH and higher titration acidity (% lactic acid). Furthermore, the organic acid content was higher in these samples. Lactic acid, the main organic acid, levels in the ayran and kefir samples were measured at their highest as 11,951.51 mg/kg and 12,989.34 mg/kg, respectively, in the UV45 sample with a radiation dose of 24 J/mL. The treatment of UV-C resulted in a minor change in the colour and textural properties of the samples. Nonetheless, this change was not significant enough to influence consumer acceptance. The application of UV-C to raw milk, depending on the radiation level used, can enhance the fermentation process in the production of ayran and kefir. This study showed that the application of UV-C has improved the quality of drinkable fermented milk products. This research has shown that, while reducing nutritional losses caused by thermal processing, microbial safety is obtained at an approximate value similar to pasteurisation. As a result, UV-C application decreases the loss of dietary compounds and provides an alternative method for microbial inactivation. Full article

The rapid and accurate identification of pathogenic spores is essential for the early diagnosis of diseases in modern agriculture. Gray mold disease, caused by Botrytis cinerea, is a significant threat to several crops and is traditionally controlled using fungicides or, alternatively, by UV-C radiation. Classically, the determination of conidial germination percentage, a key indicator for assessing pathogen viability, has been a manual, time-consuming, and error-prone process. This study proposes an approach based on deep learning, using one-stage detectors to automate the detection and counting of germinated and non-germinated conidia in microscopy images. We trained and assessed the performance of three models under several metrics: YOLOv8, YOLOv11, and RetinaNET. The results show that these three architectures provide an efficient and accurate solution for the recognition of gray mold conidia viability. Selecting the best model, we performed the task of detecting and counting conidia for determining the germination percentage on samples treated with different UV-C radiation dosages. The results show that these deep-learning models achieved counting accuracies that closely matched those obtained with conventional manual methods, yet they delivered results far more rapidly. Because they operate continuously without fatigue or operator bias, these models begin to open possibilities, after widening field tests and datasets, for efficient and fully automated monitoring pipelines for disease management in the agro-industry. Full article

Background: Skin-to-skin contact (SSC) is established as a standard of care due to its demonstrated benefits for preterm newborns, with evidence showing that earlier and more prolonged skin-to-skin contact correlates with reduced morbidity in neonates. Preterm newborns frequently require an umbilical venous catheter, and decisions regarding SSC implementation often depend on nursing staff discretion, given the limited evidence on the safety of SSC in infants with umbilical venous catheters. Aim: The primary endpoint is to explore the experiences and perceptions of parents of preterm infants with umbilical venous catheter (UVC) who engaged in SSC. Methods: This mixed-method, cross-sectional observational study. Conducted from February 2021 to January 2023 at Vall d’Hebron Hospital. The study recruited 190 participants, all progenitors of preterm neonates with umbilical venous catheters, who completed an ad-hoc survey with open and closed questions between the 7th and 10th days of the neonate’s life. Results: Descriptive analysis indicated that 74% of progenitors-initiated skin-to-skin contact within the first 48 h of life; 88.4% reported enhanced emotional well-being during hospitalization while engaging in SSC; 80.4% considered SSC a safe method; and 46.6% were satisfied with the available support furniture. Additionally, 80.4% perceived skin-to-skin contact as beneficial for the developmental progress of their preterm newborn. Phenomenological analysis identified three key categories: perceptions, support and environment. Conclusions: Promoting SSC provides substantial benefits for preterm neonates. Initiating skin-to-skin contact while the infant has an UVC supports earlier initiation and increased hours of SSC. Positive family feedback on SSC with UVC adds value to promoting this practice in neonatal units. SSC with UVC venous catheter is a safe and positive experience for parents. Information, practical support and the integration of the parents’ perspective will be key in the realization of SSC. These findings should encourage other neonatal units to review protocols and actively promote early SSC with UVC. Full article

The application of ultraviolet-C (UV-C) light has emerged as a promising non-thermal alternative to chemical preservatives in winemaking. This study investigates the efficacy of UV-C treatment on the microbial stability of Pinot noir wine during a 12-week storage period at 20 °C, with a focus on the spoilage yeast Brettanomyces bruxellensis. Microbiological analysis demonstrated complete and sustained inactivation of 10⁵ CFU/mL Brettanomyces bruxellensis after UV-C treatment with no detectable regrowth during the 12-week storage period. Untreated wine showed 1-log increase in Brettanomyces bruxellensis during the 12-week storage period and significant production of volatile esters and 4-ethylguaiacol. At the same time, a significant reduction in coumaric acid concentration was determined and attributed to Brettanomyces bruxellensis metabolism. UV-C-treated wine showed marginal increases in 4-ethylguaiacol attributed to the residual activity of Brettanomyces bruxellensis after UV-C treatment. Volatile esters did not significantly change during the 12-week storage period. The findings of this study demonstrate that UV-C treatment can ensure the microbiological storage stability of red wine. Full article

Potatoes are a vital staple crop globally, valued for their high nutritional content and yield; however, they are highly susceptible to microbial attacks, mainly during postharvest handling and storage. One of the most important potato diseases that reduces the yield and quality of potatoes is Fusarium solani. Ultraviolet-C (UV-C) irradiation has become a potential postharvest disease control method; however, its efficacy against F. solani on potatoes is poorly understood. This study investigated the in vitro and in vivo effects of UV-C irradiation against F. solani of potatoes. UV-C light (254 nm) treatment was applied to F. solani for 5, 10, and 15 min at 10, 15, and 20 cm to evaluate the in vitro effects. The treated plates were incubated at 25 °C for seven days. UV-C treatment at a 10 cm distance for 10 and 15 min successfully inhibited F. solani mycelial growth, with the 15 min exposure showing the highest inhibition rate of 57.96%. Both treatments were selected for further screening. Subsequently, ‘Sifra’ potatoes were treated with UV-C for 10 and 15 min, and the results showed low disease incidence of 33% and 22%, respectively, compared to 96% for the untreated tubers. The scanning electron microscopy assay showed broken and shrunken mycelia, along with damaged spores of F. solani, on potatoes treated with UV-C. The findings suggest that UV-C irradiation may offer a potential alternative, environmentally friendly method to chemical fungicides for controlling postharvest F. solani of potatoes. Full article

Biofilms are communities of microorganisms that pose a problem in many areas, including the food industry, drinking water treatment, and medicine, because they can contain pathogens and are difficult to eliminate. For this reason, the possibility of biofilm reduction by ultraviolet (UV) or visible light was investigated using data from published reports. Results for different applications, spectral ranges, and microorganisms were compared by performing MANOVA tests. Approximately 140 publications were found that dealt with the irradiation of water or surfaces for biofilm reduction or reduction in biofilm formation. Irradiation of surfaces with UV or visible light in the spectral range 200–525 nm had a positive effect on biofilm reduction and reduction in biofilm formation, although the results for irradiation of water were conflicting. Most investigations were carried out on P. aeruginosa biofilms, but other Gram-positive and Gram-negative bacteria, as well as some fungi and their biofilm sensitivities to irradiation, were also analyzed. Limited data were available for the UVB (280–315 nm) and UVA (315–400 nm) range. Most experiments to date have been carried out in the UVC (100–280 nm) or in the visible violet/blue spectral (400–500 nm) range, with the UVC range being 2–3 orders of magnitude more efficient in terms of applied irradiation dose. Other quantitative statements were difficult to make as the results from the different working groups were highly scattered. Irradiation can reduce the microorganisms in biofilms but does not completely remove biofilms. New biofilm formation can at least be delayed by surface irradiation. Whether it is also possible to prevent the formation of new biofilms in the long term is open to question. Which irradiation wavelengths are optimal for anti-biofilm measures is also still unclear. Full article

In the present study, the biofilm formation and ultraviolet-C (UVC) resistance characteristics of Escherichia coli isolated from an occluded biliary stent were compared with those of four E. coli O157:H7 strains (ATCC 35150, 43889, 43890, and 43895). To evaluate biofilm formation, the E. coli isolated from a stent and four E. coli O157:H7 strains were incubated at 37, 25, and 15 °C for 7 days, revealing that peak biofilm formation occurred at 37 °C (day 1), 25 °C (day 3), and 15 °C (day 5), with the stent-isolated strain consistently exhibiting significantly higher biofilm cell counts than the others (p < 0.05). The UVC treatment was less effective at reducing viable biofilm cells as the formation temperature decreased, with the stent-isolated E. coli biofilm formed at 15 °C showing the lowest reduction levels. Exopolysaccharide quantification revealed that all E. coli strains produced more extracellular polymeric substances (EPSs) at lower temperatures, with the stent-isolated E. coli biofilm formed at 15 °C showing significantly higher EPS levels than the other strains (p < 0.05), potentially explaining its greater UVC resistance. Based on these results, it was confirmed that the biofilm formed by the E. coli isolated from the stent at 15 °C exhibited the highest resistance to UVC, which can be attributed to its elevated exopolysaccharide production. This study demonstrates that both temperature and maturation period significantly influence E. coli biofilm characteristics and provides valuable insights into E. coli isolated from the stent, which may pose a risk of cross-contamination in food-related environments. Full article