UV System Research Articles

Impact of UV-based self-assessed photoaging on sun protection intentions: validation based on trail runners and their companions

Appearance-based interventions emphasize how UV exposure contributes to the premature aging of skin. The current study was aimed at evaluating the impact of self-assessed skin damage based on UV imaging on the intention to modify photoprotection habits. A prospective observational study was performed. Mountain runners and their companions participating in the GAP Trail were invited to participate. Participants were asked to complete a validated questionnaire about sun exposure habits, and were invited to see an image of their faces using SkinScope. In total, 116 people participated in the study. The degree of photoaging established by the dermatologist using the Glogau score significantly correlated with that based on self-assessment by the participants using the UV system (p < 0.001). Almost all UV fluorescence image colours significantly correlated with the grade of photoaging. After seeing their image with the UV system, 65.5% stated that they would improve photoprotection measures. UV imaging is a reliable way to self-evaluate photoaging and may reinforce photoprotection habits.

Inactivation of biofilm-bound bacterial cells using irradiation across UVC wavelengths

Opportunistic pathogens (OPs), such as Pseudomonas spp., Legionella spp., and mycobacteria, have been detected in biofilms in drinking water distribution systems and water storage tanks and pose potential risks to finished drinking water quality and safety. Emerging UV technologies, such as UV light emitting diodes (LEDs) and krypton chloride (KrCl*) excimers, could provide an alternative to chemical-based secondary disinfection (i.e., chlorine or chloramines) for controlling biofilm-bound OPs. UV systems offer long lifetimes, ability to select wavelength, small size with high power density, and limited-to-no disinfection by-product formation. In this study, inactivation of biofilm-bound Pseudomonas aeruginosa cells across different maturities was investigated using five UVC devices with different peak emission wavelengths, including a KrCl* excimer (222 nm), a low pressure mercury vapor lamp (254 nm), and three UV LEDs (260 nm, 270 nm, and 282 nm). The UV transmittance and absorbance through the biofilm structure was also documented for the first time using a unique approach. Our results show all UVC devices can inactivate biofilm-bound P. aeruginosa cells up to a point, among which the UV LED with peak emission at 270 nm provided the best disinfection performance. UV sensitivities of biofilm-bound cells decreased with biofilm maturity and while initial rates of inactivation were high, no more than 1.5-2.5 log reduction was possible. Re-suspended biofilm bacteria in aqueous solution were highly sensitive to UV, reaching greater than 6 log reduction. UV shielding by biofilm constituents was observed and was likely one of the reasons for UV resistance but did not fully explain the difference in UV sensitivity between biofilm-bound cells versus planktonic cells. This study improves upon fundamental knowledge and provides guidance for innovative designs using emerging UV technologies for biofilm and pathogen control in water distribution systems.

Synthesis of heterogeneous photo-Fenton catalyst from iron rust and its application to degradation of Acid Red 97 in aqueous medium

In this work, magnetic nanoparticles were synthesized from iron rust waste and used as a catalyst for photo-Fenton degradation of Acid red 97 (AR97). The morphology and size of Fe3O4 nanoparticles could be controlled by adding an appropriate amount of water as co-solvent in solvothermal treatment. For a comparative study, α-FeOOH and α-Fe2O3 with nanorod shape were also prepared from iron rust and employed as photo-Fenton catalyst. The photo-Fenton degradation results showed that the prepared Fe3O4 nanoparticles with spherical-like shape possessed higher catalytic activity than octahedral-shaped Fe3O4, α-FeOOH, and α-Fe2O3. It was demonstrated that the synergetic effect between H2O2 and oxalic acid (OA) led to an improvement in the catalytic efficiency of the photo-Fenton system towards AR97 degradation in awide pH range. At 180 min, about 81% of total organic carbon (TOC) was removed. Thus, the mineralization of organic matter is strongly involved during the photo-Fenton process. The quenching experiments showed that •OH radical played a crucial role in the degradation of AR97 by Fe3O4/H2O2/OA/UV system. Benefiting from the high catalytic activity and easy magnetic separation, the prepared Fe3O4 nanoparticles revealed good stability and reusability even after five consecutive cycles. This work offers a sustainable and effective way to recycle iron rust waste into an efficient catalyst for the degradation of organic contaminants in water.

UV-C Light-Based Surface Disinfection: Analysis of Its Virucidal Efficacy Using a Bacteriophage Model.

Background: The reprocessing of medical devices has become more complex due to increasing hygiene requirements. Previous studies showed satisfactory bactericidal disinfection effects of UV-C light in rigid and flexible endoscopes. Especially in the context of the current COVID-19 pandemic, virucidal properties are of high importance. In the present study, the virucidal efficacy of UV-C light surface disinfection was analyzed. Methods: MS-2 bacteriophages were applied to the test samples and irradiated by UV-C light using the UV Smart D25 device; unirradiated test samples were used as controls. A dilution series of the samples was mixed with Escherichia coli and assayed. Results: 8.6 × 1012 pfu could be harvested from the unprocessed test samples. In the control group without UV-C exposure, a remaining contamination of 1.2 × 1012 pfu was detected, resulting in a procedural baseline reduction rate with a LOG10 reduction factor of 0.72. The LOG10 reduction factor was found to be 3.0 after 25 s of UV-C light exposure. After 50 and 75 s of UV-C radiation LOG10 reduction factors 4.2 and 5.9, respectively, were found, with all reductions being statistically significantly different to baseline. Conclusions: The tested UV system seems to provide a significant virucidal effect after a relatively short irradiation time.

Chromatin landscape associated with sexual differentiation in a UV sex determination system.

In many eukaryotes, such as dioicous mosses and many algae, sex is determined by UV sex chromosomes and is expressed during the haploid phase of the life cycle. In these species, the male and female developmental programs are initiated by the presence of the U- or V-specific regions of the sex chromosomes but, as in XY and ZW systems, sexual differentiation is largely driven by autosomal sex-biased gene expression. The mechanisms underlying the regulation of sex-biased expression of genes during sexual differentiation remain elusive. Here, we investigated the extent and nature of epigenomic changes associated with UV sexual differentiation in the brown alga Ectocarpus, a model UV system. Six histone modifications were quantified in near-isogenic lines, leading to the identification of 16 chromatin signatures across the genome. Chromatin signatures correlated with levels of gene expression and histone PTMs changes in males versus females occurred preferentially at genes involved in sex-specific pathways. Despite the absence of chromosome scale dosage compensation and the fact that UV sex chromosomes recombine across most of their length, the chromatin landscape of these chromosomes was remarkably different to that of autosomes. Hotspots of evolutionary young genes in the pseudoautosomal regions appear to drive the exceptional chromatin features of UV sex chromosomes.

4D Printed Shape Memory Polymers: Morphology and Fabrication of a Functional Antenna

Shape memory polymers (SMPs) are smart materials that can respond to certain thermal, chemical or electrical stimuli by inducing a structural conformation change into a temporary shape. In this work, a 3D printing process based on a Vat Photo-polymerization of a shape memory polymer (SMP) was investigated to produce customized smart and complex morphable antennas. The mechanical and material properties were examined through a tensile, flexural and rheological testing for different polymer mixture ratios. It was observed that the combination of 20% of an elastomeric resin in a thermoset UV system yields the highest shape recovery performance. The fabrication process of the antenna was based on the incorporation of a conductive material. The approach involved the inclusion of a thin copper electroplating technique. The radiofrequency performance of the fabricated antenna was examined by a vector network analyzer (VNA) and it was observed that a thermal stimulus was capable of inducing a conformal shape on the antenna, resulting in a multi-radio frequency morphing system. The antenna performance was simulated in Ansys HFSS.

Photodegradation of F–53B in aqueous solutions through an UV/Iodide system

Advanced reduction by strong reducing hydrated electrons is a promising approach to degrade per- and polyfluoroalkyl substances (PFAS). This research aimed to investigate the effectiveness of UV/Iodide system for 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA, F–53B) degradation in aqueous solutions. Results from this work demonstrated that UV irradiation with an addition of 0.3 mM KI resulted in 55.99% degradation of F–53B within 15 min and almost 100% within 2 h. The defluorination efficiency of F–53B in the UV/Iodide system was 2.6 times higher than that in the sole UV system after 2 h of irradiation. The degradation efficiency of F–53B was not significantly affected by air purging. The defluorination efficiency with air bubbling, however, was 14.57% lower than that with nitrogen purging. The photodegradation of F–53B in the UV/Iodide system could be well described by a pseudo-first-order kinetic model. Degradation rate constant of F–53B correlated positively with the initial concentration. At 20 μg/L, the pseudo-first-order rate constant was 5.641 × 10−2 min−1 and the half-life was 12.29 min. Higher initial concentration also required less energy input to achieve the same degradation efficiency. The detection and identification of degradation intermediates implied that destruction of F–53B started from dechlorination and followed by continuously “flaking off” CF2 units.

Prevention of Airborne Transmission of SARS-CoV-2 by UV-C Illumination of Airflow

SARS-CoV-2 is frequently transmitted by aerosol, and the sterilization of the virus in airflows has numerous potential applications. We evaluated a UV-C illuminator similar to what might be incorporated into tubing of a mechanical ventilator for its ability to block transmission of the airborne virus from infected to naïve hamsters. Hamsters protected by the UV system were consistently protected from infection, whereas non-protected hamsters uniformly became infected and displayed virus shedding and high burdens of virus in respiratory tissues. The efficiency and speed with which the virus in flowing air was inactivated using this system suggests several applications for mitigating transmission of this virus.

Determination of the SLAMF1 self-association affinity constant with sedimentation velocity ultracentrifugation

Signaling lymphocytic activating molecule family member 1 (SLAMF1 or CD150) is a cell surface glycoprotein expressed on various immune populations, regulating cell-cell interactions, activation, differentiation, and inflammatory responses and has been suggested as a potential target for inflammatory diseases. Signaling is believed to be mediated by high-affinity homophilic interactions; the recombinant soluble form of SLAMF1 has optimal activity in the range of 20 μg/mL. This contradicts with a rather weak homo-dimerization binding constant (KD) value reported previously; however, the analytical approach and data analysis suffered from various technical limitations at the time and therefore warrants re-examination. To address this apparent discrepancy, we determined the KD of soluble SLAMF1 using sedimentation velocity analytical ultracentrifuge (SV-AUC). A globally fitted monomer-dimer model properly explains the data from a wide concentration range obtained with both UV and fluorescence detection systems. The analysis suggests the dimerization KD value for human SLAMF1 is 0.48 μM. Additionally, our data show that SLAMF1 self-association is not driven by non-specific binding to glycans supporting the view of specific protein-protein interaction. We anticipate antibody biotherapeutics capable of modulating the biological consequences of SLAMF1 interactions will be readily identified.

Removal of pharmaceuticals by advanced treatment methods

The removal of endocrine disrupting compounds (EDCs) remains a big challenge in water treatment in terms of public health. The aim of the study was evaluating the performance of nano TiO2, ozone, and UV system for removal of EDCs. In this study, the efficiency of the nano TiO2 to degrade target EDCs under catalytic and photocatalytic ozonation was examined at different operational conditions. The maximum removal of target pollutant was obtained with pH 6.8; ozone concentration 10 mg/L; catalyst dosage 0.050 g/L and the duration time of the photocatalytic performances was 10 min showing the most treatment conditions respectively. In addition, the surface reaction mechanism of endocrine disrupting compound removal by catalytic and photocatalytic ozonation was investigated. The results showed that the catalyst can significantly enhance the removal of target compound. The 99.0%, 88.3% and 51.8% removal rates were obtained at photocatalytic ozonation, catalytic ozonation and sole ozonation, respectively. These results indicated that the Ozone/TiO2/UV process was favorable for engineering applications for removal of endocrine disrupting compounds such as steroid hormone and likely similar micro pollutants.

Photocatalytic Detoxification of Some Insecticides in Aqueous Media Using TiO2 Nanocatalyst.

The present study was performed to fabricate a titanium dioxide (TiO2) nanocatalyst with proper characteristics for the removal of some insecticides (dimethoate and methomyl) from aqueous media. A TiO2 catalyst of regular (TiO2—commercial—/H2O2/UV) or nano (TiO2—synthesized—/H2O2/UV) size was employed as an advanced oxidation process by combining it with H2O2 under light. Moreover, the total detoxification of insecticides after treatment with the most effective system (TiO2(s)/H2O2/UV) was also investigated through exploring the biochemical alterations and histopathological changes in the liver and kidneys of the treated rats. Interestingly, the present study reported that degradation rates of the examined insecticides were faster using the TiO2 catalyst of nano size. Complete degradation of the tested insecticides (100%) was achieved under the TiO2(s)/H2O2/UV system after 320 min of irradiation. The half-life values of the tested insecticides under H2O2/TiO2(c)/UV were 43.86 and 36.28 for dimethoate and methomyl, respectively, whereas under the H2O2/TiO2(c)/UV system, the half-life values were 27.72 and 19.52 min for dimethoate and methomyl, respectively. On the other hand, no significant changes were observed in the biochemical and histopathological parameters of rats administrated with water treated with TiO2(s)/H2O2/UV compared to the control, indicating low toxicity of the TiO2 nanocatalyst-. Altogether, the advanced oxidation processes using TiO2 nanocatalyst can be considered as a promising and effective remediation technology for the complete detoxification of methomyl and dimethoate in water. However, further future research is needed to identify the possible breakdown products and to verify the safety of the used nanomaterials.

Stiefel Liquids: Possible Non-Lagrangian Quantum Criticality from Intertwined Orders

We propose a new type of quantum liquids, dubbed Stiefel liquids, based on $2+1$ dimensional nonlinear sigma models on target space $SO(N)/SO(4)$, supplemented with Wess-Zumino-Witten terms. We argue that the Stiefel liquids form a class of critical quantum liquids with extraordinary properties, such as large emergent symmetries, a cascade structure, and nontrivial quantum anomalies. We show that the well known deconfined quantum critical point and $U(1)$ Dirac spin liquid are unified as two special examples of Stiefel liquids, with $N=5$ and $N=6$, respectively. Furthermore, we conjecture that Stiefel liquids with $N>6$ are non-Lagrangian, in the sense that under renormalization group they flow to infrared (conformally invariant) fixed points that cannot be described by any renormalizable continuum Lagrangian. Such non-Lagrangian states are beyond the paradigm of parton gauge mean-field theory familiar in the study of exotic quantum liquids in condensed matter physics. The intrinsic absence of (conventional or parton-like) mean-field construction also means that, within the traditional approaches, it will be difficult to decide whether a non-Lagrangian state can actually emerge from a specific UV system (such as a lattice spin system). For this purpose we hypothesize that a quantum state is emergible from a lattice system if its quantum anomalies match with the constraints from the (generalized) Lieb-Schultz-Mattis theorems. Based on this hypothesis, we find that some of the non-Lagrangian Stiefel liquids can indeed be realized in frustrated quantum spin systems, for example, on triangular or Kagome lattice, through the intertwinement between non-coplanar magnetic orders and valence-bond-solid orders.

Weathering performance of mulberry wood with UV varnish applied and its mechanical properties

Mulberry wood is used in carpentry, fences, turnery, and garden architecture. In this study, various mechanical properties (modulus of rupture, modulus of elasticity, Janka hardness, and screw holding resistance) of mulberry (Morus alba) wood and its weathering performance after applying 3- and 5-layer UV system parquet varnishes with different surface applications were investigated. The varnished materials were aged using UV lamps for 252 h and 504 h, and the aged specimens were compared with non-aged specimens. The results of the variance analyses found that all tests were significant. According to the results, it was found that while the yellow color (b*) tone value, lightness, and glossiness (perpendicular (⊥) and parallel (║) direction at 20°, 60°, and 85° angles) values decreased for both varnish applications, the pendulum hardness value increased. The adhesion strength (pull-off) test (MPa) to the surface first decreased and then increased.

Effect of chemical activity of bulk and pad materials on the redeposition layer during polishing of glass

A near-surface redeposition layer is formed in the chemical mechanical polishing process of silicate glasses. In this work, secondary ion mass spectroscopy analyzer and transmission electron microscope are used to investigate the effect of bulk and pad materials on the microstructure and contaminations of the redeposition layer. The results suggest that the polishing materials with higher chemical reactivity will generate a deeper redeposition layer with higher concentration of contaminant elements, which will improve the surface quality by mitigating the mechanical abrasion effect. Then, a more detailed chemical mechanism of the redeposition layer formation has been concluded according to the chemical reaction and arrhenius equation, which can explain the effect of bulk materials and polishing pad on the redeposition layer well. These findings are helpful to understand the chemical process of polishing and improve the lifetime and quality of optical components especially in UV or high-power laser systems.

A partially sex-reversed giant kelp sheds light into the mechanisms of sexual differentiation in a UV sexual system.

In UV sexual systems, sex is determined during the haploid phase of the life cycle and males have a V chromosome whereas females have a U chromosome. Previous work in the brown alga Ectocarpus revealed that the V chromosome has a dominant role in male sex determination and suggested that the female developmental programme may occur by 'default'. Here, we describe the identification of a genetically male giant kelp strain presenting phenotypic features typical of a female, despite lacking the U-specific region. The conversion to the female developmental programme is however incomplete, because gametes of this feminized male are unable to produce the sperm-attracting pheromone lamoxirene. We identify the transcriptomic patterns underlying the male and female specific developmental programmes, and show that the phenotypic feminization is associated with both feminization and de-masculinization of gene expression patterns. Importantly, the feminization phenotype was associated with dramatic downregulation of two V-specific genes including a candidate male-determining gene. Our results reveal the transcriptional changes associated with sexual differentiation in a UV system, and contribute to disentangling the role of sex-linked and autosomal gene expression in the initiation of sex-specific developmental programmes. Overall, the data presented here imply that the U-specific region is not required to initiate the female developmental programme, but is critical to produce fully functional eggs, arguing against the idea that female is the 'default' sex in this species.

Specificity of UV-C LED disinfection efficacy for three N95 respirators

The recent surge in the use of UV technology for personal protective equipment (PPE) has created a unique learning opportunity for the UV industry to deepen surface disinfection knowledge, especially on surfaces with complex geometries, such as the N95 filter facepiece respirators (FFR). The work outlined in this study addresses the interconnectedness of independent variables (e.g., UV Fluence, respirator material) that require consideration when assessing UV light efficacy for disinfecting respirators. Through electron microscopy and Fourier-transform infrared (FTIR) spectroscopy, we characterized respirator filter layers and revealed that polymer type affects disinfection efficacy. Specifically, FFR layers made from polypropylene (PP) (hydrophobic in nature) resulted in higher disinfection efficiency than layers composed of polyethylene terephthalate (PET-P) (hygroscopic in nature). An analysis of elastic band materials on the respirators indicated that silicone rubber-based bands achieved higher disinfection efficiency than PET-P bands and have a woven, fabric-like texture. While there is a strong desire to repurpose respirators, through this work we demonstrated that the design of an appropriate UV system is essential and that only respirators meeting specific design criteria may be reasonable for repurposing via UV disinfection.

Modeling and validation of delivered fluence of a continuous Dean flow pilot scale UV system: monitoring fluence by biodosimetry approach

The inactivation of pathogenic microorganisms in water and high transmittance liquid foods has been studied extensively. The efficiency of the process is relatively low for treating opaque liquid foods using traditional UV systems. This study evaluated the ability of UV-C light to inactivate foodborne pathogens in a simulated opaque fluid (6.5 to 17 cm−1) at commercial relevant flow rates (31.70, 63.40, 95.10 gph) using a pilot-scale Dean Flow UV system. In this study, a mathematical model for the prediction of delivered fluence was developed by the biodosimetry method. The results revealed that increased Reduction equivalent fluence (REF) rates were observed with increased flow rates due to additional turbulence. The experimental and calculated REF were well correlated with the UV-C absorption coefficient range of 6.5 to 17 cm−1 indicating efficient mixing in the reactor. REF scaled up linearly at experimental conditions as an inverse function of flow rate and absorption coefficient, and a linear mathematical model (R2 > 0.99, p < 0.05) to predict delivered REF was developed. The model was tested and validated against independent experiments using Salmonella Typhimurium and Bacillus cereus endospores. The predicted and experimental REF values were in close agreement (p > 0.05). It is demonstrated that the developed model can predict the REF, thus microbial inactivation of microbial suspensions in simulated fluid with the absorption coefficient of 6.5–17 cm−1 and flow rates of 31.70–95.10 gph. The pilot system will be field-tested against microorganisms in highly absorbing and scattering fluids.

RP-HPLC Method Validation for the Assay of Tenofovir Disoproxil Orotate

A new Isocractic RP-HPLC method was established for the assay of Tenofovir disoproxil orotate. As per ICH guidelines, the method was validated by using a chromatographic column YMC Pack ODS-AQ, (250mm x4.6mm x 5μm particle size,) at a temperature of 300C and an Isocractic mobile phase of 0.1% Triethylamine buffer, adjusted the pH to 6.0 with ortho phosphoric and acetonitrile in the ratio of (55%: 45%) was used with a flow rate of 1.0mLmin-1. The diluent is a mixture of water and acetonitrile in the ratio of (95:5v/v) and the sample cooler temperature was 5°C. The injection volume was 10μL and detection was achieved at 260nm with UV and PDA detector system for UV detection. The % RSD, Linearity, Range, Accuracy, Precision, Ruggedness (Intermediate Precision) and Robustness are found to be satisfactory. Therefore the method is assumed to be suitable for the assay of the Tenofovir disoproxil orotate by RP-HPLC method.

Does degeneration or genetic conflict shape gene content on UV sex chromosomes?

Studies of sex chromosomes have played a central role in understanding the consequences of suppressed recombination and sex-specific inheritance among several genomic phenomena. However, we argue that these efforts will benefit from a more rigorous examination of haploid UV sex chromosome systems, in which both the female-limited (U) and male-limited (V) experience suppressed recombination and sex-limited inheritance, and both are transcriptionally active in the haploid and diploid states. We review the life cycle differences that generate UV sex chromosomes and genomic data showing that ancient UV systems have evolved independently in many eukaryotic groups, but gene movement on and off the sex chromosomes, and potentially degeneration continue to shape the current gene content of the U and V chromosomes. Although both theory and empirical data show that the evolution of UV sex chromosomes is shaped by many of the same processes that govern diploid sex chromosome systems, we highlight how the symmetrical inheritance between the UV chromosomes provide an important test of sex-limited inheritance in shaping genome architecture. We conclude by examining how genetic conflict (over sexual dimorphism, transmission-ratio distortion, or parent-offspring conflict) may drive gene gain on UV sex chromosomes, and highlight the role of breeding system in governing the action of these processes. Collectively these observations demonstrate the potential for evolutionary genomic analyses of varied UV sex chromosome systems, combined with natural history studies, to understand how genetic conflict shapes sex chromosome gene content.

Determination of the artificial aging performance of the apricot wood applied with UV system parquet varnish used indoors

Kayısı ağacı meyvesi için bol miktarda yetiştirilmektedir. Kayısı odunu farklı amaçlarla kullanılmaktadır. Bu çalışmanın amacı, kayısı (Prunus armeniaca L.) odununa uygulanmış ultraviyole (UV) sistem parke vernikli katmanların yapay yaşlandırma karşısındaki performansını belirlemektir. Bu amaç ile kayısı odunu yüzeylerine endüstriyel uygulamalara uygun olarak 3 ve 5 kat olacak şekilde UV sistem parke verniği uygulanmıştır. Elde edilen malzemeler, UVA-340 lambalı hızlandırılmış bir yaşlandırma cihazında 252 ve 504 saat süreyle maruz bırakılmıştır. Daha sonra, yaşlandırma sonrası ışıklılık (L*), kırmızı (a*) renk tonu, sarı (b*) renk tonu, 20o, 60o ve 85o’de liflere dik (⊥) ve paralel (//) parlaklık değerleri, yapışma direnci ve sarkaç sertliği (könig yöntemi) testleri belirlenmiştir. Araştırma sonuçlarına göre, bütün testler için varyans analizler anlamlı olarak elde edilmiştir. Yaşlandırmadan sonra her iki vernik uygulaması için, bütün parlaklık değerleri, sarı renk tonu ve ışıklılık değerleri azalırken, kırmızı renk tonu değerleri artmıştır. 3 katlı uygulamada sertlik azalırken yapışma direnci artmış olunup, 5 kat uygulama zıt bir sonuç vermiştir.