Conventional Lamp Research Articles

Exploring luminescent color tunability and efficient energy transfer mechanism of a single-phased hexagonal nanophosphor for white light emitting diodes (WLEDs) application

Nowadays, NUV-triggered phosphor-converted white light-emitting diodes (pc-WLEDs) have gained prominence as substantial alternatives to conventional incandescent and fluorescent lamps as a source of illumination. In this study, we have successfully developed a Tm3+ codoped La2O3:Sm3+ nanophosphor and investigated its potential suitability for application in white light-emitting diodes (WLEDs). X-ray diffraction (XRD) analysis was conducted to examine the phase impurity and structural characteristics of the synthesized nanophosphor. The analysis confirmed the formation of a single-phase La2O3 nanophosphor with a hexagonal crystal structure. The FT-IR spectrum of the synthesized nanophosphor exhibited distinct peaks associated with the vibrational frequencies of La-O bonds. The peaks observed in the fingerprint region of the spectrum, indicate the presence of La-O atoms in the nanophosphor. However, the HR-TEM analysis confirmed that the prepared nanophosphor had a polycrystalline nature and the observed particle sizes lay within the nanoscale range. The incorporation of Tm3+ ions into the host matrix led to a reduction in the optical band gap, leading to enhanced emission intensity. The photoluminescence (PL) study reveals that the Tm3+ ion exhibited blue emission upon excitation at 360 nm, whereas the Sm3+ ion emits reddish-orange light when excited at 379 nm and 408 nm, respectively. However, under 325 nm excitation, the nanophosphor exhibited a white emission color that resulted from the blending of colors emitted by both Tm3+ and Sm3+ ions. This unique finding suggests that this nanophosphor has the potential to generate white light specifically under this particular excitation wavelength. The efficient energy transfer between Tm3+ and Sm3+ ions was attributed to the electric multipolar interaction between the nearest neighbor ions, leading to a quenching phenomenon. Furthermore, the photometric analysis revealed that the correlated color temperatures (CCTs) associated with the emitted white light were found to be higher than 4000 K. Thus, based on these characteristics, it can be inferred that the prepared nanophosphor has the potential to be utilized as a cool white-emitting nanophosphor for single-phased WLEDs application.

Inactivation efficacy and mechanisms of wavelength-specific UV sources for various strains of Legionella pneumophila serogroup 1

Infections of Legionnaires' disease in the United States caused by Legionella have increased ninefold between the years 2000–2018. Legionella harbored in biofilms or inside amoeba within premise plumbing can be more resistant to disinfectants, thus causing treatment challenges. Ultraviolet-light emitting diodes (UV-LEDs) are an emerging water disinfection technology with several advantages over conventional UV lamps. In this study, we evaluated the effects of UV-LEDs (255, 265, and 285 nm), a low-pressure (LP) mercury UV lamp (254 nm), and a bandpass filtered medium-pressure (MP) mercury UV lamp (220 nm) on properties and inactivation of three strains of L. pneumophila serogroup 1. The UV-LEDs emitting at 255 and 265 nm showed greater inactivation performance against all the strains compared to the UV-LED at 285 nm and the LP UV lamp at 254 nm. Our results showed that strains of the same serogroup exhibited different UV sensitivities. Analyses of DNA and protein damage revealed that UV exposure using 254, 255, and 265 nm predominantly causes DNA damage, while protein damage is predominant at 220 nm. Both DNA and protein damage were observed at 285 nm, but the extent of DNA damage was relatively less significant compared to the other wavelengths. Electric energy consumption analysis showed that water treatment using UV-LEDs is currently unsatisfactory compared to conventional LP UV lamps due to the mediocre wall plug efficiency (WPE) of UV-LEDs. However, recent studies indicate that the WPE of UV-LEDs is continuously improving. Overall, our study highlights that UV-LEDs are a promising technology for inactivating waterborne pathogens and have the potential to replace existing UV mercury lamps for water disinfection applications.

Rapid extraction-free detection of the R132H isocitrate dehydrogenase mutation in glioma using colorimetric peptide nucleic acid-loop mediated isothermal amplification (CPNA-LAMP).

The R132H isocitrate dehydrogenase one (IDH1) mutation is a prognostic biomarker present in a subset of gliomas and is associated with heightened survival when paired with aggressive surgical resection. In this study, we establish proof-of-principle for rapid colorimetric detection of the IDH1-R132H mutation in tumor samples in under 1 hour without the need for a nucleic acid extraction. Colorimetric peptide nucleic acid loop-mediated isothermal amplification (CPNA-LAMP) utilizes 4 conventional LAMP primers, a blocking PNA probe complementary to the wild-type sequence, and a self-annealing loop primer complementary to the single nucleotide variant to only amplify the DNA sequence containing the mutation. This assay was evaluated using IDH1-WT or IDH1-R132H mutant synthetic DNA, wild-type or IDH1-R132H mutant U87MG cell lysates, and tumor lysates from archived patient samples in which the IDH1 status was previously determined using immunohistochemistry (IHC). Reactions were performed using a hot water bath and visually interpreted as positive by a pink-to-yellow color change. Results were subsequently verified using agarose gel electrophoresis. CPNA-LAMP successfully detected the R132H single nucleotide variant, and results from tumor lysates yielded 100% concordance with IHC results, including instances when the single nucleotide variant was limited to a portion of the tumor. Importantly, when testing the tumor lysates, there were no false positive or false negative results.

Comparison of the impact of UV-light emitting diode and UV lamp at pilot-plant scale level on quality parameters and consumer perception of fresh chicken meat

The present study compared the impact of two UV light devices: conventional UV lamp and UV-LED on the colour, pH, lipid and protein oxidation of fresh chicken breast meat aerobically stored at 4 °C for 10 days. Lipid oxidation was the most impacted quality attribute in UV lamp treated meat, unlike UV-LED that showed no effect compared to non-treated meat. Slight changes were observed in colour, pH and protein oxidation of chicken samples subjected to UV lamp and UV-LED. To evaluate these changes from a consumer perspective, the different treatment samples were stored at 4 °C for 3 days and colour likeness, odour likeness and overall appearance were assessed by consumer sensory analysis. However, alterations in quality parameters of chicken meat caused by UV light did not decrease overall acceptance in the sensory analysis. UV-LED was the preferred chicken meat by the participants, even compared to non-treated meat.

The effects of signboard regulation for commercial buildings: the case of a local district in the city of Seoul

ABSTRACT Disordered commercial signboards are a key source of visual chaos in the urban landscape because signboard content is presented with a variety of forms and colors. Enforcement of signboard regulations has therefore received increasing attention. However, signboards are a significant element of the urban landscape, showcasing the regional characteristics and identity of a municipal region or city. Seoul, South Korea has implemented various signboard policies aimed at improving the urban landscape, but the effect has been unsatisfactory. In this study, the effects of commercial signboard regulation were assessed in a selected district of a Seoul municipality using Analytic Hierarchy Process (AHP) perceptional analysis for both customers and business owners. Quantitative analysis found that overall signboard size was reduced by more than 80 percent after regulation. In addition, Life Cycle Cost (LCC) analysis indicates using Light Emitting Diode (LED) has a 26.4% overall cost advantage over the conventional fluorescent lamp. Notably, business owners’ responses were not negative despite the smaller signboard size. After adopting the new policy, customers ranked the signboard shape as providing the most satisfaction among various subcategories while business owners indicated high satisfaction with reduced maintenance cost.

Biochemical and functional characteristics of stored (double-dose) buffy-coat platelet concentrates treated with amotosalen and a prototype UVA light-emitting diode illuminator.

Pathogen reduction of platelet concentrates (PCs) using amotosalen and broad-spectrum UVA illumination contributes to the safety of platelet transfusion by reducing the risk of transfusion-transmitted infections. We evaluated the in vitro quality of stored buffy-coat (BC) PCs treated with amotosalen and a prototype light-emitting diode (LED) illuminator. Double-dose BC-PCs collected into PAS-III/plasma or SSP+ /plasma (55/45%) were treated with amotosalen in combination with either conventional UVA lamps (INT100 Illuminator 320-400 nm) or LED illuminators at 350 nm. Platelet quality and function were evaluated over 7 days. Platelet counts were conserved during storage in all groups, as was platelet swirling without appearance of macroscopic aggregates. Integrin αIIbβ3 and glycoprotein (GP) VI expression remained stable, whereas GPIbα and GPV declined similarly in all groups. UV lamp- and LED-treated PCs displayed similar glucose consumption, lactate generation, and pH variation. Comparable spontaneous and residual P-selectin and phosphatidylserine exposure, activated αIIbβ3 exposure, mitochondrial membrane potential, lactate dehydrogenase release, and adhesive properties under flow conditions were observed during storage. The use of SSP+ /plasma compared with PAS-III/plasma better preserved most of these parameters, especially during late storage, irrespective of the type of illuminator. Replacing the UVA lamp for photochemical treatment by LED illuminators had no impact on platelet metabolism, spontaneous activation, apoptosis or viability, or on the in vitro function of BC-PCs stored for 7 days in SSP+ or PAS-III/plasma. These findings support improved procedures for the pathogen reduction and storage of PCs, to ensure transfusion safety and retention of platelet functional properties.

The efficiency of UV light-emitting diodes (UV-LED) in decontaminating Campylobacter and Salmonella and natural microbiota in chicken breast, compared to a UV pilot-plant scale device

This study investigated the combined effect of Ultraviolet (UV) light-emitting diode (LED) technology treatment with refrigerated storage of chicken breast meat over 7 days on Campylobacter jejuni, Salmonella enterica serovar Typhimurium, total viable counts (TVC) and total Enterobacteriaceae counts (TEC). An optimised UV-LED treatment at 280 nm for 6 min decreased inoculated S. Typhimurium and C. jejuni populations by 0.6–0.64 log CFU/g, and TVC and TEC population by 1–1.2 log CFU/g in chicken samples. During a 7-day storage at 4 °C, a 0.73 log reduction in C. jejuni was achieved compared with non-treated samples. Moreover, the UV-LED effectiveness to reduce TVC and TEC during refrigerated storage was compared with a conventional UV lamp and a similar efficiency was observed. The impact of UV-LED and UV lamp devices on the microbial community composition of chicken meat during storage was further examined using 16 S rRNA gene amplicon sequencing. Although similar bacterial reductions were observed for both technologies, the microbial communities were impacted differently. Treatment with the UV conventional lamp increased the proportion of Brochothrix spp. In meat samples, whilst Photobacterium spp. Levels were reduced.

The Water Disinfection with Different Type UV Lamp Systems on Bacterial Load in Small Scale Recirculating Aquaculture Systems

The present study was planned with the aim of inactivating the total bacterial load and species in tilapia fish tanks kept in fresh and seawater conditions with high stock density with different UV lamp models. In this context, the UVC+UVA-Led lamp system was compared with the conventional UVC lamp system and the total bacterial load in the tanks and the inactivation effect on the bacterial species were determined. Total bacterial load on the medium and bacteria species were identified in terms of their morphological characteristics using the spread plate method. Bacteria that emerged at different times in the trial sets were identified as Edwardsiella tarda, Salmonella sp., Aeromonas hydrophila, Pantoea sp., Citrobacter youngae, Serratia ficaria and Citrobacter freundii. The total bacterial load in both freshwater and seawater environments in both lamp groups showed a decrease compared to the control group. With this, the conventional lamp model was more effective on the total bacterial load in the samples taken during the trial. Although all bacteria were inactive in both lamp groups, Serratia ficaria bacteria were not eliminated in the seawater environment. The results show that UV LEDs can be a better alternative to traditional UV mercury lamps for water disinfection.

Efficacy of UV and UV-LEDs Irradiation Models for Microbial Inactivation Applicable to Automated Sterile Drug Compounding

LEDs development has attracted attention over conventional mercury lamps for the tiny size, high efficiency, long lifetime, low operating temperature. The antimicrobial effectiveness of traditional UV-lamps radiation (wavelength of 254 nm) compared to UV-C LEDs (LED1 wavelength range 275–286 nm and LED2 range 260–270 nm) was carried out, for possible applications to automated sterile drug compounding. The UV lamp and the tested UV-LED devices remarkably reduced microbial load, following a time-dose response, but the best performance was evidenced by LED1, which guaranteed the complete inactivation of high concentrations of bacteria, yeasts, and spores at doses between 200 and 2000 J/m2.

Interobserver Reliability of Tear Break-Up Time Examination Using "Smart Eye Camera" in Indonesian Remote Area.

Dry eye disease (DED) is a multifactorial disease of tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability leading to decrease of vision, productivity and quality of life, and blindness. DED diagnosis remains difficult and underdiagnosed regarding inconsistency between subjective symptoms and clinical findings. Tear break-up time (TBUT) is an objective indicator of tear film stability in diagnostic DED. A novel smartphone attachment, namely SEC (smart eye camera), could mimic conventional slit lamp to assess TBUT and beneficial in facilitating DED diagnosis. Reliability between a non and an ophthalmologist in TBUT assessment and DED diagnosis is observed in this study. To determine interobserver reliability of TBUT measurement for diagnosing DED using SEC. This a cross-sectional analytic study involving 99 participants (198 eyes) aged 40 years who visited Pratama Gema Santi Hospital, Nusa Penida, from September 2nd to 4th, 2022, with consecutive sampling technique. Fluoresceined eyes were filmed using the SEC device and apps, continued by masked ophthalmologist and resident assessing TBUT based on the video. The primary outcome is interobserver reliability for TBUT measurement and DED diagnosis. The mean age of participants was 55.22±9.78 years, 48.5% male and 51.5% female. The reliability of interobserver in assessing DED based on TBUT test is 0.78 (95% CI=0.31-1.26, P-value=0.001), and interobserver reliability in diagnosing DED based on OSDI and TBUT showed good agreement (weighted kappa=0.71). Good interobserver reliability underscores that non-ophthalmologists can diagnose DED based on TBUT video using SEC. SEC video has good interobserver reliability to assess TBUT for DED diagnosis. SEC can be used as one of the methods in assessing DED in limited health care facilities. The high reliability of interobserver assessment indicates that DED diagnosis using video taken with SEC may be useful for telemedicine evaluation in remote areas.

Energy Efficiency of LEDs during Micropropagation of Helleborus ‘Molly’s White’

For many years, there has been a growing trend toward producing plants using tissue culture, the most efficient method at present. Every year, more and more protocols for micropropagation of economically valuable species are appearing. Many factors influence the regenerating explants under sterile laboratory conditions. One of the most important is light. The aim of the present study was to increase the efficiency of micropropagation of hellebore ‘Molly’s White’ using energy-efficient light-emitting diodes (LEDs), which were compared to traditionally used fluorescent lamps (FLs). To choose the best light and reduce production costs, white, blue or red LEDs with two levels of photosynthetic photon flux density (PPFD), 40 and 70 μmol/m2/s, were used at the multiplication and rooting stages. LED light color has been shown to affect regeneration rate and plant growth in length during micropropagation, while both light parameters (color as well as intensity) affect the length of regenerating shoots and the content of assimilation pigments in plants. The use of white LED light, which gives the highest multiplication rate, at an intensity of 70 μmol/m2/s saves more than 57 kWh during an 8-week micropropagation cycle compared to conventional fluorescent lamps with the same parameters.

A study establishing sensitivity and accuracy of smartphone photography in ophthalmologic community outreach programs: Review of a smart eye camera.

Diseases affecting the cornea are a major cause of corneal blindness globally. The pressing issue we are facing today is the lack of diagnostic devices in rural areas to diagnose these conditions. The aim of the study is to establish sensitivity and accuracy of smartphone photography using a smart eye camera (SEC) in ophthalmologic community outreach programs. In this pilot study, a prospective non-randomized comparative analysis of inter-observer variability of anterior segment imaging recorded using an SEC was performed. Consecutive 100 patients with corneal pathologies, who visited the cornea specialty outpatient clinic, were enrolled. They were examined with a conventional non-portable slit lamp by a cornea consultant, and the diagnoses were recorded. This was compared with the diagnoses made by two other consultants based on SEC videos of the anterior segment of the same 100 patients. The accuracy of SEC was accessed using sensitivity, specificity, PPV, and NPV. Kappa statistics was used to find the agreement between two consultants by using STATA 17.0 (Texas, USA). There was agreement between the two consultants to diagnosing by using SEC. Above 90% agreements were found in all the diagnoses, which were statistically significant (P-value < 0.001). More than 90% sensitivity and a negative predictive value were found. SEC can be used successfully in the community outreach programs like field visits, eye camps, teleophthalmology, and community centers, where either a clinical setup is lacking or ophthalmologists are not available.

Superiority of UV222 radiation by in situ aquatic electrode KrCl excimer in disinfecting waterborne pathogens: Mechanism and efficacy

Microbial safety in water has always been the focus of attention, especially during the COVID-19 pandemic. Development of green, efficient and safe disinfection technology is the key to control the spread of pathogenic microorganisms. Here, an in situ aquatic electrode KrCl excimer radiation with main emission wavelength 222 nm (UV222) was designed and used to disinfect model waterborne virus and bacteria, i.e. phage MS2, E. coli and S. aureus. High inactivation efficacy and diversity of inactivation mechanisms of UV222 were proved by comparision with those of commercial UV254. UV222 could totally inactivate MS2, E. coli and S. aureus with initial concentrations of ∼107 PFU or CFU mL−1 within 20, 15, and 36 mJ/cm2, respectively. The UV dose required by UV254 to inactivate the same logarithmic pathogenic microorganism is at least twice that of UV222. The protein, genomic and cell membrane irreparable damage contributed to the microbial inactivation by UV222, but UV254 only act on nucleic acid of the target microorganisms. We found that UV222 damage nucleic acid with almost the same or even higher efficacy with UV254. In addition, free base damage of UV222 in similar ways with UV254(dimer and hydrate). But due to the quantum yield of free base degradation of UV222 was greater than UV254, the photolysis rates of UV222 to A, G, C and U four bases were 11.5, 1.2, 3.2 and 1 times as those of UV254, respectively. Excellent disinfection performance in UV222 irradiation was also achieved in real water matrices (WWTP and Lake). In addition, it was proved that coexisting HCO3- or HPO42 – in real and synthetic water matrices can produce • OH to promote UV222 disinfection. This study provided novel insight into the UV222 disinfection process and demonstrated its possibility to take place of the conventional ultraviolet mercury lamp in water purification.

Lumpy Skin Disease (LSD): Etiology, Pathogenesis, Prevention and Control

Lumpy skin disease (LSD) is one of the diseases that pose a threat to the livestock industry because it can cause large economic losses. The disease was first discovered in the country of Zambia in 1929. In Indonesia, LSD was first discovered in early 2022 in Indragiri Hulu Regency, Riau. This disease is caused by a virus belonging to the genus Capripoxvirus, subfamily chordopoxvirinae, family Poxviridae. The LSD virus has a limited host and does not infect non-ruminant hosts. A characteristic clinical symptom of LSD is the appearance of nodules on the skin. Diagnosis of this disease can be done by looking at typical clinical symptoms, laboratory tests such as virus isolation, serological tests (serum neutralization test, virus neutralization test (VNT), agar gel immune diffusion, indirect ELISA, and indirect fluorescent antibody technique (IFAT)), real time and conventional PCR, immunohistochemistry, LAMP, and IPMA. Prevention and control of LSD disease can be done in several ways such as vaccination, vector control, restriction of livestock traffic, strict quarantine and stamping out.

Aluminum Nitride Ultraviolet Light-Emitting Device Excited via Carbon Nanotube Field-Emission Electron Beam

With the progress of wide bandgap semiconductors, compact solid-state light-emitting devices for the ultraviolet wavelength region are of considerable technological interest as alternatives to conventional ultraviolet lamps in recent years. Here, the potential of aluminum nitride (AlN) as an ultraviolet luminescent material was studied. An ultraviolet light-emitting device, equipped with a carbon nanotube (CNT) array as the field-emission excitation source and AlN thin film as cathodoluminescent material, was fabricated. In operation, square high-voltage pulses with a 100 Hz repetition frequency and a 10% duty ratio were applied to the anode. The output spectra reveal a dominant ultraviolet emission at 330 nm with a short-wavelength shoulder at 285 nm, which increases with the anode driving voltage. This work has explored the potential of AlN thin film as a cathodoluminescent material and provides a platform for investigating other ultrawide bandgap (UWBG) semiconductors. Furthermore, while using AlN thin film and a carbon nanotube array as electrodes, this ultraviolet cathodoluminescent device can be more compact and versatile than conventional lamps. It is anticipated to be useful in a variety of applications such as photochemistry, biotechnology and optoelectronics devices.

Smart streetlight system using mobile applications: secured fault detection and diagnosis with optimal powers

A street lighting system is a very essential part of the highways and streets of a smart city. Managing power consumption and maintenance of a street light system will be a challenging task in huge countries. The proposed work is mainly focused on the minimization of power consumption in the implementation of a smart street lighting system. Also, use a mobile application for setting up the brightness levels of the lamps in an encrypted form so that an unauthorized person will not be able to modify the settings. In the existing streetlight system, wireless sensors are installed to control and monitor the streetlamps. In the proposed system, using an nRF24L01 radio transceiver module, a secured communication link is established to operate the streetlights depending on the ambient weather conditions, movement of humans, vehicles and any other objects. A failsafe mechanism is implemented in the modules for conventional lamp operation in the case of module failures. Light-dependent resistor (LDR) is used to determine the ambient brightness levels to automatically turn on/off the streetlights based on weather conditions and lighting on roads. Using smartphones, we access and control the brightness information from the master node at which the nRF24L01 radio transceiver module is installed, and the same information is relayed to all the slave nodes. The results show that we could effectively monitor and control the brightness of streetlights in a secure way and there is a significant amount of power savings. The proposed system saves the average powers of 53.45%, 44.76%, 39.39%, and 32.25% respectively for 10%, 20%, 30%, and 50% idle mode brightness compared to the state-of-the-art techniques present in the literature.

Short-Wave Ultraviolet-Light-Based Disinfection of Surface Environment Using Light-Emitting Diodes: A New Approach to Prevent Health-Care-Associated Infections.

Ultraviolet (UV)-C irradiation is a promising method for microbial eradication on surfaces. Major developments have taken place in UV-C light-emitting diodes (LEDs) technology. In this study, we examined the suitability of UV-C LED-based surface disinfection in hospitals. We tested the efficacy of UV-C LED surface treatment on different microorganisms dried on a carrier surface or in a liquid solution. The influences of soiling, shading, surface material, radiation wavelength, microbial load and species on the disinfection performance were investigated. UV-C LED caused a reduction of >5 log10 levels of E. coli, S. aureus and C. albicans, whereas 3 log10 reduction was observed for G. stearothermophilus spores. The components of the medium led to a reduced UV-C LED efficiency compared to buffered solutions. We observed that the microbial load and the roughness of the carrier surface had a major influence on the UV-C LED disinfection efficiencies, whereas shading had no impact on inactivation. This study showed that UV-C is suitable for surface disinfection, but only under certain conditions. We showed that the main factors influencing microbial inactivation through UV-C light (e.g., intrinsic and extrinsic factors) had a similar impact when using a UV-C LED radiation source compared to a conventional UV-C lamp. However, the potential of LEDs is contributed by their adjustable wavelength and customizable geometry for the decontamination of medical devices and surfaces, and thereby their ability to overcome shading effects.

Inactivation of foodborne pathogenic bacteria in water and stainless steel surfaces by vacuum-UV amalgam lamp and low-pressure mercury UV lamp irradiation

The objective of this study was to investigate the inactivation mechanism of a vacuum-ultraviolet (VUV)-amalgam lamp and its bactericidal efficacy on a stainless-steel surface and water compared with that of a conventional low-pressure mercury ultraviolet (LP) lamp. When treated with the VUV-amalgam and LP lamp over distilled water, initial 6–7 log CFU/mL of the foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes) were inactivated over 4.5 log after 60 mJ/cm2 treatment. However, there was no significant difference (p > 0.05) from the action of the VUV-amalgam lamp and conventional LP lamp at the same dose. However, on the stainless steel surface, the VUV-amalgam lamp treatment showed over 1.5 log higher inactivation capacity against the three pathogens at the same 254 nm dose irradiation of the LP lamp. Results of this study suggested that the VUV-amalgam lamp can be applied as a potential substitute for a conventional LP lamp for surface disinfection and limited water disinfection if ozone generation is well controlled.

Reflection of UVC wavelengths from common materials during surface UV disinfection: Assessment of human UV exposure and ozone generation

The COVID-19 pandemic has promoted interest in using devices emitting ultraviolet-C (UVC) irradiation (200–280 nm) for surface disinfection to reduce pathogen transmission, especially in occupied public spaces. While UVC devices have been shown to be highly effective against various pathogens, there are safety concerns when using conventional UVC devices for surface disinfection, including human exposure of reflected UVC irradiation and ozone generation. Emerging Far UVC devices (emitting at 200–230 nm), like the krypton chloride (KrCl*) excimer, have the potential to be safely applied in occupied spaces due to their minimal adverse effects on skin and eyes. In this study, UV reflection of 21 common materials was documented and compared using a filtered KrCl* excimer (installed with a bandpass filter at 222 nm), an unfiltered KrCl* excimer, and a conventional low-pressure mercury vapor lamp. The safety of Far UVC devices was evaluated based on the irradiance and spectrum of reflected UV irradiation and ozone generation measured at various locations around the device. Our results show that most common materials can reflect UV irradiation, among which some metals tend to have greater reflection. The Far UVC devices, especially the filtered KrCl* excimer, should be safe to be applied in occupied spaces for effective surface disinfection, with limited ozone generation and no health risk from reflected UV irradiation. However more caution is needed when using unfiltered KrCl* devices and conventional UV 254 nm light. This study provides urgently needed data on UV reflection of common materials and guidance for safety assessments of UVC devices for surface disinfection in occupied spaces.

RNase H2 triggered visual loop-mediated isothermal amplification combining smartphone assisted all-in-one aptamer magnetic enrichment device for ultrasensitive culture-independent detection of Salmonella Typhimurium in chicken meat

Pre-enrichment cultural continues to remain time-consuming and labor-intensive in the detection of low-concentration bacteria in meat samples. Culture-independent detection method is urgently needed in POCT technology. In order to be able to proceed with culture-independent pre-enrichment for low-concentration pathogen detection, a RNase H2 enzyme triggered all-in-one device-based visual Loop-mediated Isothermal Amplification detection method was developed, combining with Salmonella Typhimurium specific Aptamer Magnetic Enrichment steps, termed as the AME-LAMP method. In order to better enable the AME-LAMP method to perform on-site culture-independent detection, a palm-held all-in-one device (PAD) was designed and manufactured. Further, a self-developed smart phone fluorescence analysis app could complete end-point detection, thus eliminating miscalculation. RNase H2 Enzyme triggered AME-LAMP method could detect Salmonella as low as 5.5 CFU/mL while conventional LAMP only detected 550 CFU/mL. By verifying the detection performance of AME-LAMP methods in chicken meat samples, AME-LAMP shows the potential to achieve ultrasensitive Salmonella detection by comparing with ISO isolation method and normal LAMP. With the assistance of smart phone-based PAD, it can be reliably applied for the on-site culture-independent detection of Salmonella Typhimurium.