Uv light disinfection

Far-UVC light in the wavelength range of 200-230 nm has attracted renewed interest because of its safety for human exposure and effectiveness in inactivating pathogens. Here we present a compact solid-state far-UVC laser source based on second-harmonic generation (SHG) using a low-cost commercially-available blue laser diode pump. Leveraging the high intensity of light in a nanophotonic waveguide and heterogeneous integration, our approach achieves Cherenkov phase-matching across a bonded interface consisting of a silicon nitride (SiN) waveguide and a beta barium borate (BBO) nonlinear crystal...

Ultraviolet radiation's germicidal efficacy depends on several parameters, including wavelength, radiant exposure, microbial physiology, biological matrices, and surfaces. In this work, several ultraviolet radiation sources (a low-pressure mercury lamp, a KrCl excimer, and four UV LEDs) emitting continuous or pulsed irradiation were compared. The greatest log reductions in E. coli cells and B. subtilis endospores were 4.1 ± 0.2 (18 mJ cm-2 ) and 4.5 ± 0.1 (42 mJ cm-2 ) with continuous 222 nm, respectively...

STATEMENT OF PROBLEM: Disinfection is an important factor in preserving facial prostheses and maintaining tissue health. However, whether disinfection with ultraviolet C is an effective disinfection method is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effectiveness of irradiation with different exposure durations of an ultraviolet-C light-emitting diode in the disinfection of the silicone (A-588-1; Factor II) used in facial prostheses...

Ultraviolet (UV) light is widely used for wastewater disinfection. Traditional electrode-excited UV lamps, such as low-pressure mercy lamps (LPUV), encounter drawbacks like electrode aging and rapid light attenuation. A novel UV source of microwave discharge electrodeless lamp (MDEL) has aroused attention, yet its disinfection performance is unclear and still far from practical application. Here, we successfully developed a complete piece of equipment based on MDELs and achieved the application for disinfection in wastewater treatment plants (WWTPs)...

UV light emitting diodes (LEDs) are considered the new frontier of UV water disinfection. As UV technologies continue to evolve, so does the need to understand disinfection mechanisms to ensure that UV treatment continues to adequately protect public health. In this research, two Escherichia coli (E. coli) strains (the wild type K12 MG1655 and K12 SP11 (ThiI E342K)) were irradiated with UV-C at 268 nm both independently and after exposure to UV-A (365 nm). A synergistic effect was found on the viability of the wild type E...

Ultraviolet light-emitting diodes (UV-LEDs), as a novel ultraviolet light source with flexible pulse mode, has gained significant attention for applications in water disinfection and food sterilization. This study investigated the comparative inactivation efficiency of Tetraselmis sp. with continuous and pulsed UV-LEDs irradiation, exploring different wavelengths, duty rates and pulse frequencies. The results reveal a significant enhancement in inactivation efficiency (p < 0.05) under pulsed conditions even at the same UV dose, with inactivation efficiency increasing as duty rate or pulse frequency decreases...

Iodine is a vital microelement and a powerful antiseptic with a rapid and broad spectrum of action. The development of iodophor compounds to improve the solubility and stability of iodine is still challenging. Here, we report the synthesis of a novel cationic β-cyclodextrin bearing a choline-like pendant (β-CD-Chol) designed to complex and deliver iodine to bacterial cells. The characterization of β-CD-Chol and the investigation of the inclusion complex with iodine were performed by NMR spectroscopy, mass spectrometry, UV-vis spectrophotometry, isothermal titration calorimetry, and dynamic light scattering...

Infectious diseases caused by waterborne viruses have attracted researchers' great attention. To ensure a safe water environment, it is important to advance water treatment and disinfection technology. Photocatalytic technology offers an efficient and practical approach for achieving this goal. This paper reviews the latest studies on visible-light composite catalysts for bacteriophage inactivation, with a main focus on three distinct categories: modified UV materials, direct visible-light materials and carbon-based materials...

AIMS: To test the efficacy of 222 nm Far UV-C for surface disinfection of SARS-CoV-2 on inanimate surfaces from airplane cabins. METHODS AND RESULTS: Two far ultraviolet (UV-C) irradiation light systems were evaluated for disinfection of SARS-CoV-2. Materials used for carriers (test surfaces) included polished stainless steel and used airplane materials including seatbelt latches, window dust covers, sidewall laminates, and tray tables. CONCLUSIONS: While demonstrating reasonable efficacy under some experimental conditions, the data indicated that 222 nm Far UV-C disinfection alone does not reliably provide a 3 log10 or 99...

The development of a full-spectrum responsive photocatalytic germicide with excellent charge separation efficiency to harvest high antimicrobial efficacy is a key goal yet a challenging conundrum. Herein, graphitic carbon nitride nanosheet (PCNS)/Ti3 C2 Tx MXene/TiO2 (PMT) Z-scheme heterojunctions with robust interface contact were crafted by in situ interfacial engineering. The strong internal electrical field (IEF) from PCNS to TiO2 , evinced by the Kelvin Probe Force Microscopy (KPFM) characterization, can obtain high charge separation efficiency with 73...

Microplastics have emerged as a concerning contaminant in drinking water sources, potentially interacting with pathogenic microorganisms and affecting the disinfection processes. In this study, MS2 was selected as an alternative for the human enteric virus. The influence of microplastics polyvinylchloride (MPs-PVC) on ultraviolet light emitting diode (UV-LED) inactivation of MS2 was investigated under various water chemistry conditions, such as MPs-PVC concentration, pH, salinity, and humic acid concentration...

Microplastics (MPs) have entered drinking water (DW) via various pathways, raising concerns about their potential health impacts. This study provides a comprehensive review of MP-associated chemicals, such as oligomers, plasticizers, stabilizers, and ultraviolet (UV) filters that can be leached out during DW treatment and distribution. The leaching of these chemicals is influenced by various environmental and operating factors, with three major ones identified: MP concentration and polymer type, pH, and contact time...

Photocatalytic disinfection of Escherichia coli suspension by silicon dioxide nanoparticles and silicon dioxide/gold nanocomposite in a batch reactor is investigated experimentally and results are compared. Silica nanoparticles were synthesized by Stöber method and pulsed laser ablation method was employed to prepare gold nanoparticles in distilled water. Composition of two nanoparticles species was carried out, using the second harmonic pulse of Nd:YAG laser, whose wavelength is in the absorption spectra of gold nanoparticles...

The use of urban wastewater reclaimed water has recently increased across the globe to restore stream environmental flows and mitigate the effects of water scarcity. Reclaimed water is disinfected using different treatments, but their effects into the receiving rivers are little studied. Physiological bioassays and biomarkers can detect sub-lethal effects on target species, but do not provide information on changes in community structure. In contrast, official monitoring programs use community structure information but often at coarse taxonomic resolution level that may fail to detect species level impacts...

BACKGROUND: Chlorine-based disinfectants, such as bleach, are commonly used for cleaning in healthcare settings to prevent the transmission of nosocomial pathogens. To enhance the efficacy of disinfection, ultraviolet-C (UV-C) light systems have been proposed to supplement standard cleaning procedures. As bleach decomposes in UV light, we hypothesised that the use of UV-C light as an adjunct to manual cleaning with bleach, may decrease the efficacy of disinfection instead. METHODS: In the laboratory, stainless steel sheets and plastic keyboards were inoculated with Pseudomonas aeruginosa (∼106 CFU/ml) and subjected to treatment with either UV-C light only, bleach only or a combination of UV-C light and bleach...

Indoor air, especially with suspended particulate matter (PM), can be a carrier of airborne infectious pathogens. Without sufficient ventilation, airborne infectious diseases can be transmitted from one person to another. Indoor air quality (IAQ) significantly impacts people's daily lives as people spend 90% of their time indoors. An industrial-grade air cleaner prototype (filtration + ultraviolet light) was previously upgraded to clean indoor air to improve IAQ on two metrics: particulate matter (PM) and viable airborne bacteria...

The past decade's development of UV LEDs has fueled significant research in water disinfection, with widespread debate surrounding the potential synergies of multiple UV wavelengths. This study analyses the use of three UV sources (265, 275, and 310 nm) on the inactivation of Escherichia coli bacteria in two water matrixes . At maximum intensity in wastewater, individual inactivation experiments in a single pass set-up (Flow rate = 2 L min-1 , Residence time = 0.75 s) confirmed the 265 nm light source to be the most effective (2...

Assessment of the impact of contemporary disinfection techniques Moringa Oleifera (M. Oleifera), NanoCare Plus Silver Gold® (Nanocare), and Fullerene (C60) on survival rates of S.Mutans and shear bond strength (SBS) of composite to the carious affected dentin (CAD) MATERIAL AND METHODS: Sixty mandibular molars having caries progression till the middle 1/3rd of the dentin were disinfected. The CAD surface of twenty samples was inoculated with S.mutans. Based on different disinfection regimens samples were arbitrarily assigned to four groups (n:15) Group 1: 2% CHX, Group 2:NanoCare, Group 3:Fullerene (C60), and Group 4 (M...

Abstract In this study, the effect of baffle configuration on the water disinfection efficiency of a planar photoreactor equipped with ultraviolet C light-emitting diodes (UV-C LEDs) was investigated. The results indicated that the configuration of the baffles influenced the hydrodynamics inside the flow channel and thus affected the microbial trajectory, and exposure time. Accordingly, a modified serpentine configuration was developed to enhance the UV light exposure of microbes in water and improve the reactor performance for microbial inactivation...

Somatic coliphages (SC) and F-specific RNA coliphages (FRNAPH) have been included in regulations or guidelines by several developed countries as a way of monitoring water safety and the microbiological quality of shellfish harvesting waters. SC are highly diverse in their morphology, size and genome. The Microviridae family contains three genera of phages (Alphatrevirus, Gequatrovirus, and Sinsheimervirus), all having a capsid of similar morphology (icosahedral) and size (25-30 nm in diameter) to that of common pathogenic enteric viruses...