Disproportionate decline in ultraviolet versus visible light penetration in lakes across land-use gradients, with implication for the deep chlorophyll maximum

Numerous insect species exhibiting positive phototaxis are strongly attracted to ultraviolet (UV) light. However, several heteropteran stink bugs, including Nezara viridula (L.) and its congener Nezara antennata Scott, show stronger attraction to traps combining UV and green light than to monochromatic UV light traps. To examine the role of visible light wavelengths in enhancing UV attraction, we evaluated the attractiveness of blue (469 nm), green (523 nm), orange (613 nm), and red (632 nm) light in combination with UV light (396-400 nm), as well as a monochromatic UV light source, under field conditions targeting Nezara bugs. Traps combining UV and blue light captured nearly three times more Nezara bugs than UV-only light traps. Conversely, traps combining orange or red and UV light captured equal to or fewer bugs than monochromatic UV light traps, indicating no enhancement in attraction with these color combinations. Furthermore, monochromatic blue light alone showed very weak attractiveness, indicating that blue light synergistically enhanced the attractiveness of UV light to bugs. Strong attractiveness to traps combining UV and green light was confirmed in the lepidopteran moth Pleuroptya ruralis (Scopoli), suggesting that multiwavelength light sources may be effective in attracting insect species beyond Heteroptera. These findings highlight the value of multiwavelength light traps, particularly traps combining UV and blue light, for improving stink bug monitoring and pest management.

A photodetector (PD) featuring dual-band detection capability and self-powering attributes is crucial for various applications in sensing, communication, and imaging. Here, we present a self-powered PD based on a solution-processed CuInS2/SnO2 heterojunction capable of detecting ultraviolet (UV) and visible light spectra. The CuInS2 layer was composed of ∼2 nm-sized quantum dots (QDs) synthesized using the hot injection method, while the SnO2 layer was fabricated using a straightforward sol-gel technique. This self-powered PD displayed a significant spectral response across both UV (355 nm) and visible light (532 nm) ranges, all accomplished without the need for external bias. The PD demonstrates rapid detection, with rise and decay times of 125 ms and 156ms for visible light and 85 ms and 200 ms for UV light, respectively, at a power level of 15 mW. The PD achieved responsivity values of 10.66 μA/W and 34.56 μA/W for visible and UV light, respectively. The impressive capability for dual-band detection in both ultraviolet (UV) and visible light showcases the practical feasibility and utility of this device for self-powered photodetection and deciphering UV-encrypted visible light communication. Moreover, its straightforward solution-based processing attribute renders it valuable for the mass production of devices and technology.

In this study the photolightening behavior of blond hair was investigated. The results demonstrated that visible (VIS) and ultraviolet (UV) light lighten blond hair through different mechanisms. VIS light was found to contribute much more to the lightening of blond hair than UV light, and acted directly, while UV light only lightened blond hair that had been washed following irradiation. VIS and UV light both, however, lightened to a similar degree isolated melanin granules and decomposed melanin granules that were exposed on a cross section of blond hair. These results indicate that melanin granules are equally sensitive to both forms of light while blond hair is most sensitive to VIS light. The results also indicate that hair tissues, excluding melanin granules, are damaged by UV light but not by VIS light. Based on these facts, the hypothetical lightening mechanism of UV light is assumed to be that UV light preferentially attacks and damages hair tissues rather than melanin granules. This occurs only after the hair is washed, as the washing process removes the melanin granules that effuse from loose hair fibers. In contrast, VIS light preferentially attacks and decomposes the melanin granules rather than other tissues, and also results in the lightening of blond hair but without the need for subsequent washing. We also found that while VIS light destroys the structure of isolated melanin granules, UV light does not act in a similar manner. Consequently, it is proven that VIS and UV light attack different sites of the melanin granule, even though the lightening rates from both light sources are similar.

Eye Problems in Mountain and Remote Areas: Prevention and Onsite Treatment—Official Recommendations of the International Commission for Mountain Emergency Medicine ICAR MEDCOM

Iodine-based titanium dioxide composite (I-TiO2) was prepared by following the trouble-free hydrolysis method using iodic acid and tetrabutyl titanate. The prepared TiO2 and I-TiO2 composites have been characterized by XRD, SEM, UV-visible spectroscopy, EDS, and FTIR spectroscopy. The anatase TiO2 was confirmed by XRD diffraction patterns with 5.699 nm in size. The successful synthesis of TiO2 both pure and doped was studied by FTIR spectroscopy. The photocatalytic activity of the prepared materials was investigated for degradation of organic dyes such as methyl orange (MO) and congo red (CR) with the irradiation of visible and ultraviolet (UV) light. The efficacy of the degradation of MO using I-TiO2 (15%) was 6.75 and 36.89 times greater than that using pure TiO2 with the irradiation of UV and visible light, respectively. Similarly, I-TiO2 (15%) showed superior photocatalytic activity to degrade CR compared to bare TiO2 by irradiation with both visible and UV light. The largest degradation (99% under UV and 89% under visible light) of the MO was obtained using I-TiO2 (15%) as catalyst after 210 minutes. The reuse of I-TiO2 (15%) as catalyst was also investigated showing negligible reduction of photocatalytic efficiency.

In order to utilize solar light in an efficient way, a good photocatalyst shall absorb both UV and visible light. In this study, a series of composite photocatalyst consisting of zinc oxide (ZnO) and carbon nitride (CN) was successfully prepared through a physical mixing method. The ZnO is an ultraviolet (UV)-based photocatalyst, while the CN is known as a visible light-driven photocatalyst. The effect of zinc to carbon mol ratio (Zn/C) towards the properties and photocatalytic activities was investigated. X-ray diffraction (XRD) patterns revealed that the prepared ZnO-CN composite photocatalysts composed of wurtzite ZnO and graphitic CN. The presence of ZnO and CN made the composites have absorption at both UV and visible region, suggesting the potential application as photocatalysts under both UV and visible light. Fluorescence studies revealed that all ZnO-CN composites showed emission peaks at 445 and 460 nm when excited at 273 nm, but with lower intensity as compared to those of the CN. The lower emission intensity suggested the role of ZnO to reduce the charge recombination and improve the charge separation on the CN. The ZnO-CN composites were further evaluated for photocatalytic degradation of phenol. The amount of degraded phenol was determined by a gas chromatography, in which a flame ionization detector was used in this study (GC-FID). The composite photocatalyst with an optimum content of 1% Zn/C gave almost 1.15 times higher activity than the CN under visible light irradiation. On the other hand, the composite photocatalyst with an optimum content of 50% Zn/C showed 2.6 times higher activity than the CN under UV light. The improved photocatalytic efficiency on the ZnO-CN composite photocatalysts was caused by the synergic effect between ZnO and CN. The ZnO would boost the separation efficiency of photogenerated electrons on the CN, while the CN would enable ZnO to absorb visible light region as the ZnO-CN composites.

We have carried out the first systematic study of the effects of ultraviolet light, both alone and in combination with visible white light, on Turing patterns in the chlorine dioxide-iodine-malonic acid (CDIMA) reaction. The ultraviolet light used has a sharp peak at 368 nm and can perturb the system selectively. It primarily decomposes chlorine dioxide in a zeroth-order reaction, and when it is used to illuminate Turing patterns, shrunken spots are formed with an imperfect hexagonal arrangement. The ultraviolet light competes directly with the visible white light via the photoreaction with dissolved chlorine dioxide, which prevents the total suppression of patterns at intermediate intensities of white light. These results suggest that specific wavelengths of light in the ultraviolet spectrum selectively modify the chemistry behind the pattern formation and can be utilized to generate novel self-organized structures under forcing conditions. We propose a modified Lengyel-Epstein model to incorporate the effect of ultraviolet illumination and obtain good qualitative agreement between simulations and experiments. These results support the idea that chlorine dioxide photoreaction is a key step in modulating CDIMA patterns under ultraviolet illumination.

Factors Affecting Sperm Motility. III. Influence of Visible Light and Other Electromagnetic Radiations on Human Sperm Velocity and Survival

Titanium dioxide (TiO2), a well-known photocatalyst, was incorporated into poly(vinyl alcohol) (PVA) nanofibers via electrospinning to develop self-cleaning textile materials that can decompose organic contaminants and stains on the textile surface by light irradiation. TiO2/PVA nanocomposite fiber webs were prepared from PVA solutions that contained 5, 10, and 20 wt% TiO2 nanoparticles. The morphologies and chemical compositions of the composite fibers were characterized using scanning electron microscopy, transmission electron microscopy, and an energy dispersive X-ray analysis system. The TiO2/PVA nanocomposite fiber webs were thermally treated to increase their stability in an aqueous environment. To evaluate the self-cleaning performance, the fiber webs were saturated using a methylene blue dye solution and red wine. Different light sources, i.e., ultraviolet (UV) light, visible light, and fluorescent light, were used to examine their effects on the photocatalytic self-cleaning activities of the TiO2/PVA nanocomposite fiber webs. The color changes of the methylene blue and red wine stains on the fiber webs were assessed with the time of light exposure over a period of 24 h. The results depicted that the decomposition rates of the methylene blue and red wine stains by the fiber webs varied in the order of fluorescent light < visible light < UV light. Generally, the decomposition rate increased by increasing the time of light exposure and the TiO2 concentration. Our findings demonstrated the self-cleaning performance of the electrospun composite fibers containing TiO2 nanoparticles not only under UV light but also under visible and fluorescent light that are commonly used indoors.

Do Tengmalm's owls see vole scent marks visible in ultraviolet light?

Vitamin B2 (V-B2) is a material that converts shorter-wavelength light such as ultraviolet (UV) light to longer-wavelength light. However, it is not clear whether longer-wavelength light is produced by the irradiation of alpha particles. Because UV light such as Cherenkov light is required to produce longer-wavelength light for V-B2 and alpha particles do not produce Cherenkov light in a material, no light is expected to be emitted in V-B2 by the irradiation of alpha particles. However, we irradiated alpha particles to a V-B2 plate and measured the produced light in the plate. During irradiation of alpha particles, a significant amount of longer-wavelength light was observed from the V-B2 plate. The luminescence intensity of the V-B2 plate during irradiation of alpha particles was ∼1/6 of that of the plastic scintillator. The spectrum of luminescence from the V-B2 plate during this irradiation was the same as that emitted by the irradiation of ultraviolet (UV) light, which possibly indicates UV or shorter-wavelength light production in the V-B2 plate by the irradiation of alpha particles. This longer-wavelength light is not attributed to the UV light from the air scintillation by the alpha particles but to the direct irradiation of alpha particles to the V-B2 plate. From these results, we conclude that the luminescence of the V-B2 plate was the scintillation by the irradiation of alpha particles, or other phenomenon that was; UV as well as shorter-wavelength visible light was produced in the V-B2 plate by the irradiation of alpha particles and that the longer-wavelength light was produced from this light. The UV light was produced from the light generated by the dipole interaction of moving secondary electrons with V-B2 or binder molecules and then converted to the longer-wavelength light with a slower decay of the V-B2 in the plate that had high intensity due to the decreased simultaneity of the light emission.

Exploring novel Zr2GeX (X = C, N, F) MAX phases by first-principles approach

Clean indoor air is crucial for human lives in residential and workplace settings, including food safety and supply chains. Since the COVID-19 outbreak, disinfecting air has become vital for the public as the SARS-CoV-2 virus and other infectious diseases transmit via inhalable aerosols. Ultraviolet (UV) light is known to be effective in disinfecting air. However, it is still challenging to properly design practical UV applications with common light design software. Visible light analysis software, AGi32, assists architectural applications. AGi32 utilizes digitized luminaire IES files to model light intensity on user-designed geometry in common far-field uses. IES files are based on far-field photometry to model light intensity at different distances and angles from the source. The common application of IES files is to model visible light intensities; however, IES files generated for UV light are still rarely available. Due to the increasing need for surface and air disinfection, modeling UV light intensity using IES files may be beneficial for designing and evaluating systems containing UV light bulbs in near-field applications. There is limited information regarding the accuracy of UV modeling in AGi32 software using IES files. Therefore, the research objectives were to (1) create IES files of a UV-C germicidal lamp (254 nm) and a visible fluorescent lamp with almost identical metrics; (2) compare the IES files output with physical UV measurements inside and outside of an air duct; (3) develop correlations between light intensities of visible and UV light bulbs. Linear correlations were observed when comparing UV irradiance and visible illuminance for both measured and modeled data. The results indicated high variability between the measured and modeled light data, signifying the importance of further investigation of potential error sources and improving the accuracy of modeling.

Exposure to ultraviolet (UV) light has both physiological benefits as well as costs. Many lepidosaur reptiles can behaviorally self-regulate their exposure to UV light in order to take advantage of the benefits of UV light while minimizing the costs. Furthermore, lepidosaur scales have been conceptualized by some as a barrier to the penetration of UV light. Here we examine regulation of self-exposure to UV light in three different phenotypes of Bearded Dragon (Pogona vitticeps): wild type, animals exhibiting scales of reduced prominence (‘Leatherback'), and scaleless animals (‘Silkback'). Silkbacks on average chose to expose themselves to lower levels of UV light irradiation than Leatherbacks or wild types did. Bearded Dragons of all scalation phenotypes on average received higher UV irradiation when they were in the cold section of a UV gradient apparatus compared to when they were in the hot section of the apparatus. This either demonstrates that Bearded Dragons under higher UV irradiances choose cooler temperatures or demonstrates that Bearded Dragons at cooler temperatures choose higher UV irradiances. The relationship between chosen temperature and chosen UV light irradiance was not affected by scalation phenotype. This study highlights external influences on the mechanism that regulates UV self-exposure behavior in lepidosaur reptiles.

The expansion of dye pollutants overburdened the environment and consequently increased pollution. Photodegradation and adsorption are one of the most efficient processes for water treatment. Metal oxides have been studied for this application. Amongst of metal oxides, Tin(II) oxide semiconductor and its modification are interesting. In this work, Tin(II) oxide nanoplates/chitosan in an ionic liquid media was prepared. This mild method was done in ethyl pyridinium iodide ionic liquid. The structural character of this composite was examined by XRD, TEM, AFM, and DRS techniques. The TEM results showed that this composite consisted of plate morphology. The photocatalysis experiments were carried out by irradiating in ultraviolet and visible light of dyes containing Blue 133 (B133), and Reactive Red 66 (R66). By combining the good semiconductor properties of Tin(II) oxide and the high adsorption of chitosan, the composite is promising for the photocatalytic removal of organic dyes. The Langmuir adsorption isotherm model was used to study the adsorption-photodegradation process of dye molecules on this composite. The results revealed that the highest removal efficiency of Blue 133 under visible light was 45.48%, whereas achieved under ultraviolet light 98.41%. Also, the degradation percentage of Reactive Red 66 by composite remained 98.85%, under ultraviolet light, the removal efficiency decreased to 46.12%, while visible light. The presence of chitosan enhanced the photodegradation-adsorption properties directed towards visible light.