Search Results (136)

This study investigates the chemical and sensory effects of UV-C disinfection on black, white, green, and pink peppercorns using a scalable mechanical drum reactor. While previous research has demonstrated the efficacy of UV-C radiation in microbial disinfection, there is a lack of deep, quality-focused research on food products. Nevertheless, for spices, this is just as important, if not more so, than food safety. Different analyses were conducted to assess changes in volatile compounds, organic acids, fatty acids, tocopherols, and colour following UV-C exposure. Additionally, sensory evaluations were performed using triangular tests to determine whether these chemical changes were perceptible to consumers. Results revealed that many of the measured chemical components were affected by the UV treatment, with some volatile compounds decreasing by up to 90%, while certain organic acids increased by more than 150%. Despite these changes, no significant differences in colour, aroma, or flavour were detected by the sensory panel across all pepper types. These findings suggest that UV-C irradiation, when applied under the tested conditions, preserves the sensory quality of peppercorns, supporting its potential as a non-thermal processing method for spice treatment. Full article

Nosocomial infections caused by Candida albicans pose serious challenges to healthcare systems due to their persistence on medical surfaces and resistance to conventional disinfectants. This study evaluates antifungal properties of SnO₂ doped with silver and cuprite nanoparticles and WO₃ thin films, as well as cobalt (CoFe₂O₄) and cobalt–nickel (Co_0.5Ni₀.₅Fe₂O₄) ferrite nanoparticles, activated by ultraviolet C (UVC) radiation, direct electric current (up to 100 V), and magnetic fields. SnO₂ films were synthesized by Spray Pyrolysis and WO₃ by Sputtering deposition, Ferrites nanoparticles by sol–gel, while metallic nanoparticles were synthetized via chemical reduction. Characterization consisted mainly of SEM, TEM, and XRD, and their antimicrobial activity was tested against C. albicans. WO₃ films achieved 86.2% fungal inhibition after 5 min of UVC exposure. SnO₂ films doped with nanoparticles reached 100% inhibition when combined with UVC and 100 V. Ferrite nanoparticles alone showed moderate activity (21.9%–40.4%) but exhibited strong surface adhesion to fungal cells, indicating potential for magnetically guided antifungal therapies. These results demonstrate the feasibility of using multifunctional nanomaterials for rapid, non-chemical disinfection. The materials are low-cost, scalable, and adaptable to hospital settings, making them promising candidates for reducing healthcare-associated fungal infections through advanced surface sterilization technologies. Full article

Candida albicans, listed by WHO as a priority fungal (yeast) pathogen, can cause invasive infections resistant to drugs, thus demanding novel strategies of disinfection. This study examines the inactivation, reactivation in darkness, and susceptibility to fluconazole of an antifungal-resistant C. albicans strain through UVC photolysis, chemical oxidation, and photooxidation using hydrogen peroxide (H₂O₂), peroxydisulfate (PDS), or peroxymonosulfate (PMS). Tests were performed in deionized water over very short treatment times (0–80 s). Also, standardized CLSI methods for antifungal sensitivity studies and morphological microscopic views were carried out. The fungus disinfection order was UVC/H₂O₂ > UVC/PDS > UVC/PMS > UVC. The photooxidation processes followed pseudo-first-order kinetics, with the highest rate constant for the UVC/H₂O₂ process. Direct oxidation, photoinactivation, and attacks of radical species were responsible for the inactivation of the antifungal-resistant microorganism. The fluconazole susceptibility of yeasts was significantly decreased (from 64 to 8 µg mL⁻¹) by the action of UVC/H₂O₂. A low reactivation in the dark and strong changes in the yeast morphology were found, indicating that the use of UVC light and radical-based processes is an effective alternative for fluconazole-resistant yeasts and could be promising to deal with hospital wastewater loaded with resistant fungi. Full article

Microbial contamination of food can lead to faster spoilage and infections. Therefore, disinfection processes are required that have a low detrimental effect on the nutritional content. Concerning radiation disinfection, two spectral ranges have recently become important. The Far-UVC spectral range, with a wavelength below 230 nm and visible violet light. In this study, leaf spinach was used to investigate the extent to which these radiations inactivate Escherichia coli, but also to determine if the vitamin C or chlorophyll content was reduced. Frozen spinach leaves (Spinacia oleracea) were contaminated with E. coli × pGLO and irradiated with either a 222 nm krypton chloride lamp or 405 nm LEDs. The achieved bacterial reduction was determined by plating the irradiated samples on agar plates and subsequent colony counting. The vitamin C concentration was determined by means of redox titration, and the concentrations of chlorophyll a and chlorophyll b were determined using spectrometry. Both irradiations exhibited a strong antimicrobial impact on E. coli. The average log reduction doses were about 19 mJ/cm² (222 nm) and 87 J/cm² (405 nm), respectively. The vitamin C concentration decreased by 30% (222 nm) or 20% (405 nm), and the chlorophyll concentrations decreased by about 25%. Both irradiation approaches are able to substantially reduce microorganisms on spinach leaves by two orders of magnitude, but this is associated with a reduction in the nutrient content. 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

This study investigates the AI-assisted analyses of radiation disinfection effects on the mechanical properties of recycled date kernel powder–epoxy composites for medical applications, utilizing Euclidean distances and the k-nearest neighbor (KNN) algorithm. Tensile and compression tests were conducted on twenty specimens following ASTM standards, with the data analyzed using a t-test to evaluate the impact of the UVC disinfection process on the material’s mechanical properties. The application of AI through the KNN algorithm successfully identified the three most representative curves out of five for both tensile and compression tests. This targeted curve selection minimized variability and focused on the most relevant data, enhancing the reliability of the analysis. Following the application of UVC and AI, tensile tests showed a 20–30% increase in ultimate stress. Similarly, compression tests revealed a 25% increase in transition stress, an 18–22% improvement in ultimate stress, and approximately a 12% rise in fracture stress. This research underscores the potential of combining AI, sustainable materials, and UVC technology to develop advanced composites for medical applications. The proposed methodology offers a robust framework for evaluating material performance while promoting the creation of eco-friendly, high-performance materials that meet the stringent standards of medical use. Full article

The customization and handling of implant abutments in prosthetic laboratories can lead to microbial contamination, requiring disinfection before clinical use. This study evaluated cross-contamination in abutments from three prosthetic laboratories, identifying microorganisms and assessing the disinfection efficacy of 2% chlorhexidine digluconate (2% CL) and ultraviolet C (UV-C) radiation. Sixty abutments were analyzed, with contamination detected in 83%, predominantly Enterococcus faecalis (34.2%) and Staphylococcus epidermidis (17.8%). Post-disinfection, CFU reduction was 92% (UV-C) and 93% (CL), confirmed by the Wilcoxon test (Z = −4.373; p < 0.001). A comparative analysis using the Kruskal–Wallis test showed no significant difference between the two methods (p > 0.05). These findings confirm that both UV-C and CL effectively reduce microbial load, providing reliable disinfection protocols for clinical practice. 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

In the post-COVID era, international business and tourism are quickly recovering from the global lockdown, with people and products traveling faster at higher frequency. This boosts the economy while facilitating the spread of pathogens, causing waves of COVID aftershock with new variants like Omicron XBB. Hence, continuous disinfection of our living environments becomes our first priority. Autonomous disinfection robots provide an efficient solution to this issue. Compared to human cleaners, disinfection robots are able to operate tirelessly in harsh environments without increasing the risk of cross-infection. In this paper, we propose the design of a new generation of the Smart Cleaner disinfection robot, which is equipped with both an Ultraviolet-C (UVC) light tower and a hydrogen peroxide (HP) aerosol dispenser. The safety of an autonomous disinfection robot has been a persistent problem, especially when they work in complex environments. To tackle this problem, Hamilton–Jacobi (HJ) reachability is adopted to construct a safety filter for motion control, which guarantees that the disinfection path taken by the robot is collision-free without severely compromising the optimality of control actions. The effectiveness of the developed robot has been demonstrated by conducting extensive experimental studies. Full article

A professional closet with highly efficient disinfection for reusing protective clothing is required to reduce supply and demand and protect the environment. A self-developed ultraviolet-C (UVC) light-emitting diode (LED) package that can emit uniform radiance in a certain distance was developed; and a series of disinfection modules with UVC LED packages were installed in a closet for disinfection. A disinfection module can achieve an over 99.9% disinfection rate of H1N1; E. coli; S. aureus; Pseudomonas aeruginosa; and an over 99% disinfection rate of EV71 within a minute. A 1-min disinfection closet was developed to reuse protective clothing. The closet was well-designed; as well as a series of burn-in tests were performed after the assembly of the closet. The optical and thermal properties of the closet were stable within one minute of a working period during the burn-in test. After disinfection; bacterial filtration efficiency (BFE) and viral filtration efficiency (VFE) were examined on the disposable protective clothing. The disposable protective clothing did not show any degradation after being exposed to UVC for sixty minutes; which means the defensive capability of medical protective clothing can be reused sixty times in light of the self-developed disinfection closet. The disinfection closet provides an efficient method for reusing protective clothing. Full article

UV-C LEDs, which offer short-wavelength characteristics and serve as an alternative to traditional UV mercury lamps, represent a new light source for applications in space decontamination and surface disinfection. This paper presents the design and development of a UV-C LED lamp driver circuit configured to operate with a DC-input voltage source for sterilization and germicidal purposes. The primary circuit integrates a modified buck converter with a flyback converter, resulting in an innovative single-stage, single-switch DC-DC power converter. Additionally, the proposed electronic driver recovers energy stored in the transformer’s leakage inductors, enhancing overall circuit efficiency. A prototype driver circuit with a 3.3 W power rating (10 V/330 mA) is developed for a UV-C LED lamp intended for sterilization and germicidal applications with a DC-input voltage source. The experimental results from the prototype circuit, tested at an 18 V DC input, confirm the functionality of the proposed electronic driver for UV-C LED sterilization and germicidal lighting. Additionally, the circuit achieves efficiency exceeding 91%. Full article

Purpose: The COVID-19 pandemic led to a major interest in ultraviolet C (UVC) disinfection devices and accelerated the implementation of UVC devices in healthcare facilities due to their proven efficacy in the inactivation of various pathogens. While UVC technology offers several advantages, some drawbacks remain. This report, drawing on studies, guidelines, and practical experiences related to the use of UVC technology in healthcare settings, examines the efficacy, advantages, and drawbacks of UVC devices, and their applications in aseptic drug-compounding pharmaceutical units. Summary: Studies, guidelines, and practical experiences were selected. UVC technology offers advantages such as rapid disinfection, reduced reliance on chemical agents, minimal waste, and freedom from manual disinfection variability, making it particularly valuable for maintaining aseptic conditions in compounding environments. However, some drawbacks persist, as it is a germ-dependent method and there is currently no standardized method for ensuring effectiveness. Conclusions: This opinion paper highlights the effectiveness of UCV technology in pharmaceutical compounding units, proving that it is a viable alternative to the traditionally used manual and operator-dependent methods. However, there is a need for standardized methods to evaluate UVC devices. Full article

Background: More effective and automated techniques for disinfecting elevator push-buttons currently need to be developed, especially given that they are frequently touched by hundreds of individuals. Methods: An automatic elevator push-button disinfection device equipped with four 265 nm ultraviolet-C (UVC) light-emitting diode (LED) packages has been developed for disinfection after each touch to reduce the risk of infection. In this paper, the UVC leakage test, UVC LED package reliability test, and bacteria disinfection efficiency test were performed. Results: The disinfection efficiency for Staphylococcus aureus and Escherichia coli can reach over 90% in 10 s, and end users can set multiple disinfection periods in light of their circumstances. The disinfection device is safe for the human body if the distance exceeds 120 mm. The accelerated aging test result demonstrates that the disinfection device is reliable under normal operation and end-users can increase the disinfection time by compensating for the irradiance drop. Conclusions: The automatic elevator push-button disinfection device provides a safe, highly efficient, and stable disinfection solution for elevator push-buttons. Full article

Fresh produce contamination poses a significant public health risk. Traditional disinfection methods using chemical solutions, while effective, raise environmental and health concerns. This study explores UVC irradiation, a promising non-chemical alternative proven to be effective against a broad spectrum of microorganisms. We investigated the optimal UVC dosage for reducing microorganisms on fresh vegetables washed in water. Our findings suggest that dosages of approximately 2 mJ/cm² in water and 9 mJ/cm² in vegetables achieve reductions of up to 99%. Additionally, we established a nominal radiation application rate of 2.38 mW/cm²/s, reflecting the treatment intensity. Understanding the fundamental mechanisms of UVC irradiation and its interactions with microorganisms is crucial. Elucidating these mechanisms can significantly improve optimization efforts and seamlessly integrate UVC irradiation into food safety protocols. Implementing this strategy offers immense potential to elevate food safety standards in the industry while minimizing environmental impact. This approach aligns perfectly with sustainability objectives by providing a chemical-free solution for food disinfection. Full article

Public touchscreens, such as those used in automated teller machines or ticket payment systems, which are accessed by different people in a short period of time, could transmit pathogens and thus spread infections. Therefore, the aim of this study was to develop and test a prototype of a touchscreen system for the public sector that disinfects itself quickly and automatically between two users without harming any humans. A quartz pane was installed in front of a commercial 19” monitor, into which 120 UVC LEDs emitted laterally. The quartz plate acted as a light guide and irradiated microorganisms on its surface, but—due to total reflection—not the user in front of the screen. A near-infrared commercial touch frame was installed to recognize touch. The antibacterial effect was tested through intentional staphylococcus contamination. The prototype, composed of a Raspberry Pi microcomputer with a display, a touchscreen, and a touch frame, was developed, and a simple game was programmed that briefly switched on the UVC LEDs between two users. The antimicrobial effect was so strong that 1% of the maximum UVC LED current was sufficient for a 99.9% staphylococcus reduction within 25 s. At 17.5% of the maximum current, no bacteria were observed after 5 s. The residual UVC irradiance at a distance of 100 mm in front of the screen was only 0.18 and 2.8 µW/cm² for the two currents, respectively. This would allow users to stay in front of the system for 287 or 18 min, even if the LEDs were to emit UVC continuously and not be turned off after a few seconds as in the presented device. Therefore, fast, automatic touchscreen disinfection with UVC LEDs is already possible today, and with higher currents, disinfection durations below 1 s seems to be feasible, while the light guide approach virtually prevents the direct irradiation of the human user. Full article