Broadband Ultraviolet Radiation Research Articles

Biobased-interlayer glass composite with improved mechanical properties and ultraviolet radiation shielding

This paper reports a biobased-interlayer glass composite that augments the flexural strength and stiffness of glass and Ultraviolet protection. The benign interlayer consists of polyvinyl alcohol, lignin, and citric acid as a crosslinker. The interlayer was doctor bladed on soda-lime glass, encrusted by a second glass, dried, then heat-treated to warrant its strength and durability. Three-point bending tests disclosed an improvement in flexural strength (53.1%), flexural strain (43.1%), and flexural stiffness (9.4%) in contrast to the pristine glass. Furthermore, the laminated glass effectively shields broadband Ultraviolet radiation and concurrently displays outstanding transparency over 75% in the visible range. This research offers an innovative design approach for robust Ultraviolet shielding and strengthening of glass in a facile and cost-effective manner. Future applications of this novel composite include greenhouse cover, automobile windshields, security, and museum artwork.

Transcriptomic Effects of Acute Ultraviolet Radiation Exposure on Two Syntrichia Mosses.

Ultraviolet radiation (UVR) is a major environmental stressor for terrestrial plants. Here we investigated genetic responses to acute broadband UVR exposure in the highly desiccation-tolerant mosses Syntrichia caninervis and Syntrichia ruralis, using a comparative transcriptomics approach. We explored whether UVR protection is physiologically plastic and induced by UVR exposure, addressing the following questions: (1) What is the timeline of changes in the transcriptome with acute UVR exposure in these two species? (2) What genes are involved in the UVR response? and (3) How do the two species differ in their transcriptomic response to UVR? There were remarkable differences between the two species after 10 and 30 min of UVR exposure, including no overlap in significantly differentially abundant transcripts (DATs) after 10 min of UVR exposure and more than twice as many DATs for S. caninervis as there were for S. ruralis. Photosynthesis-related transcripts were involved in the response of S. ruralis to UVR, while membrane-related transcripts were indicated in the response of S. caninervis. In both species, transcripts involved in oxidative stress and those important for desiccation tolerance (such as late embryogenesis abundant genes and early light-inducible protein genes) were involved in response to UVR, suggesting possible roles in UVR tolerance and cross-talk with desiccation tolerance in these species. The results of this study suggest potential UVR-induced responses that may have roles outside of UVR tolerance, and that the response to URV is different in these two species, perhaps a reflection of adaptation to different environmental conditions.

Effect mass independent isotope fractionation of sulfur (δ33S and δ36S) during photolysis SO2 in experiments with broadband light source

This paper presents the results of experimental studies to examine the behavior of mass-independent isotope effects of sulfur Δ33S and Δ36S during photochemical processes initiated by broadband ultraviolet radiation. Experiments were performed in a flow photochemical reactor using a high pressure mercury lamp which is a source of radiation of a wide range with a maximum radiation intensity in the wavelength range 270-330 nm and weaker in the range 190-250 nm. We present measurements of the temperature and SO2 pressure dependence of the sulfur isotope ratios in the elemental sulfur products. Based on a comparative analysis of our isotope data with data from previous experimental studies with xenon and hydrogen lamps, it was shown that the character of the correlation dependences between the values of δ34S, Δ33S and Δ36S in elemental sulfur depends on the relative spectral distribution of the radiation intensity. Based on a comparison of our isotope data with data from previous experimental studies with xenon and hydrogen lamps, it was shown that the character of the correlation dependencies between the values of δ34S, Δ33S and Δ36S in elemental sulfur depends on the relative spectral distribution of the radiation intensity. The results of our experiments allow the possibility that photochemical processes in the range 250-330 nm could play a significant role in the production of an isotope sulfur anomaly in the Archean atmosphere. The conditions in which radiation in the 250-330 nm region prevail over the radiation in the 190-220 nm region are consistent with the assumption that the level of solar radiation reaching the Earth’s surface in Archean was several orders of magnitude larger in the wavelength range 200-300 nm compared with the current level of radiation in this range.

Effect of Mass-Independent Isotope Fractionation of Sulfur (Δ33S and Δ36S) during SO2 Photolysis in Experiments with a Broadband Light Source

Abstract–This paper presents the results of experimental studies of the behavior of mass-independent isotope effects of sulfur Δ33S and Δ36S during photochemical processes initiated by a broadband ultraviolet radiation. Experiments were performed in a flow photochemical reactor using a high-pressure mercury lamp, which is a source of radiation of a wide range with maximum radiation intensity in the wavelength range of 270−330 nm and weaker intensity in the range of 190−250 nm. The temperature and SO2 pressure dependences of the sulfur isotope ratios in the elemental sulfur products are revealed. Based on a comparative analysis of our isotope data with data from previous experimental studies with xenon and hydrogen lamps, it was shown that the correlation between the values of δ34S, Δ33S and Δ36S in elemental sulfur depends on the relative spectral distribution of the radiation intensity. Based on a comparison of our isotope data with data from previous experimental studies with xenon and hydrogen lamps, it was shown that the correlation between the values of δ34S, Δ33S and Δ36S in elemental sulfur depends on the relative spectral distribution of the radiation intensity. Our experiments suggest that photochemical processes in the range of 250−330 nm could play a significant role in the production of an isotope sulfur anomaly in the Archean atmosphere. The conditions in which 250− 330 nm radiation prevails over the 190−220 nm radiation are consistent with the assumption that the level of solar radiation reaching the Earth’s surface in Archean was several orders of magnitude higher in the wavelength range 200−300 nm compared with the current level of radiation in this range.

Long‐Term, High‐Voltage, and High‐Temperature Stable Dual‐Mode, Low Dark Current Broadband Ultraviolet Photodetector Based on Solution‐Cast r‐GO on MBE‐Grown Highly Resistive GaN

AbstractNew generation of hybrid photodetectors may provide the optimal solution for compact, highly sensitive, durable, and reliable broadband ultraviolet (BUV) sensors. A high‐performance dual‐mode BUV photodetector based on melding of highly resistive GaN and reduced graphene oxide is reported. Under zero bias, the device exhibits a sub‐picoampere dark current, high light‐to‐dark current (ILight/IDark) ratio of ≈3.8 × 103 and high BUV–visible rejection ratio (≈1.8 × 102) with fast rise and fall times. The photodetector displays remarkable stability when subject to extreme operating conditions. The photoresponse of the detector shows a dark current of ≈2.41 nA at ± 200 V bias, ILight/IDark ratio of ≈200 and high BUV–vis rejection ratio (≈7 × 102). The response time of device is typically in the range of 15–27 ms measured at 12 Hz light chopping frequency. When subjected to high working temperature of up to 116 °C, it shows a stable optical switching response. In addition, the device displays impressive long‐term stability with no change in photoresponse even after a period of 28 months. This unique combination of low dark current, dual‐mode operation, and no aging effects upon prolonged exposure to high‐operating voltage, high‐temperature, and BUV radiation is attractive for a variety of harsh environment applications.

Accelerated ageing of organic LED panels using ultraviolet exposure

Two different types of commercial organic LED panels were aged with ultraviolet light. One type was aged in an over-filled and open circuit condition with broadband ultraviolet radiation, and the other in an under-filled and closed circuit condition with spectrally dispersed light. Both the luminance values and the spectral power distributions of the panels were measured for both types. The results show that the light output and the spectrum of the panel decay faster when the panels are exposed to ultraviolet radiation when compared to natural ageing. For the panels aged using the under-filled method, the wavelength that reduces the output most is between 320 nm and 340 nm, and the ultraviolet exposure with wavelengths longer than 350 nm did not accelerate the ageing. The ultraviolet radiation exposure increased the ageing by a factor of eight as compared to natural ageing, when the used ultraviolet levels corresponded to one year of exposure on a clear summer day condition. Based on the results, the under-filled method is a valid option for accelerated ageing, especially for studying simultaneously accelerated and natural ageing.

Multifunctional Photostable Nanocomplex of ZnO Quantum Dots and Avobenzone via the Promotion of Enolate Tautomer.

Ideal multifunctional ultraviolet radiation (UVR) absorbents with excellent photostability, high molar absorptivity, broadband UVR screening, and desired skin sensorial properties remain a significant challenge for the sunscreen industry. The potential of the nanocomplex (NCx) formed by microwave synthesis of ZnO quantum dots (QDs) in the presence of Avobenzone (Av) for achieving these goals is reported. The NCx exhibits unique synergy between ZnO QD and Av components, which enhances the photostability and molar absorptivity, extends UVA filtering range, and provides a visible emission that matches the typical human in vivo skin emission color. Density functional theory (DFT) and time‐dependent DFT calculations of ZnO‐Av hybrid structures and comparison of their spectroscopic features with experiments suggest that ZnO QDs catalyze the formation of highly photostable surface enolate species via aldol condensation reaction. The combination of experiments and computations used in this study can advance the science and technology of photoprotection.

UV Soliton Dynamics and Raman-Enhanced Supercontinuum Generation in Photonic Crystal Fiber

Ultrafast broadband ultraviolet radiation is of importance in spectroscopy and photochemistry, since high photon energies enable single-photon excitations and ultrashort pulses allow time-resolved studies. Here we report the use of gas-filled hollow-core photonic crystal fibers (HC-PCFs) for efficient ultrafast nonlinear optics in the ultraviolet. Soliton self-compression of 400 nm pulses of (unprecedentedly low) ~500 nJ energies down to sub-6-fs durations is achieved, as well as resonant emission of tunable dispersive waves from these solitons. In addition, we discuss the generation of a flat supercontinuum extending from the deep ultraviolet to the visible in a hydrogen-filled HC-PCF. Comparisons with argon-filled fibers show that the enhanced Raman gain at high frequencies makes the hydrogen system more efficient. As HC-PCF technology develops, we expect these fiber-based ultraviolet sources to lead to new applications.

Solar urticaria in 145 patients: Assessment of action spectra and impact on quality of life in adults and children

Solar urticaria (SU) is a rare chronic inducible urticaria triggered via uncharacterized chromophores. We detail responses of a large patient series to monochromator phototesting and broadband ultraviolet radiation (UVR); relationship to life quality is explored. Retrospective review of all SU patients undergoing standardized diagnostic photoinvestigation at a specialist centre during 2000-2016. From 2011, patients completed dermatology life quality index (DLQI) questionnaires for the past week and year. In 145 patients (mean: 35.8, range: 3-69years; 18 aged <18years; 100 female), combined phototesting with broadband UVR and monochromator sources successfully provoked 74.5% patients, with 65.6% provoked by broadband UVR alone and 57.9% by monochromated radiation alone. The narrow wavebands most frequently eliciting wheal and flare response were between 370 and 400nm, with 25% patients at 300±5nm, 53.6% at 320±10nm, 66.7% at 330±10nm, 77.4% at 350±20nm, 83.3% at 370±20nm, 86.9% at 400±20nm, 44% at 500±20nm and 17.8% at 600±20nm. In 62 patients, the DLQI revealed 56.1% had very to extremely large impact in the past week (all patients: mean score: 11.1, range: 0-29) rising to 69.8% for the past year (12.5, 0-30); adults and children were similarly affected. Patients with positive photoprovocation had higher DLQI score than those who were negative (DLQI for past week: mean: 12.6±SEM 1.1 vs 4.6±1.4, P<.01). SU is predominantly provoked by longer UVA-shorter visible radiation, which penetrates window-glass and where sunscreens are less effective; impact on life quality is considerable. Photoprotective agents effective against this spectrum are needed.

Ultraviolet germicidal efficacy as a function of pulsed radiation parameters studied by spore film dosimetry

Disinfection by pulsed ultraviolet (UV) radiation is a commonly used method, e.g. in industry or medicine and can be carried out either with lasers or broadband UV radiation sources. Detrimental effects to biological materials depending on parameters such as pulse duration τ or pulse repetition frequency fp are well-understood for pulsed coherent UV radiation, however, relatively little is known for its incoherent variant. Therefore, within this work, it is the first time that disinfection rates of pulsed and continuous (cw) incoherent UV radiation studied by means of spore film dosimetry are presented, compared with each other, and in a second step further investigated regarding two pulse parameters. After analyzing the dynamic range of the Bacillus subtilis spore films with variable cw radiant exposures H=5–100Jm−2 a validation of the Bunsen-Roscoe law revealed its restricted applicability and a 28% enhanced detrimental effect of pulsed compared to cw incoherent UV radiation. A radiant exposure H=50Jm−2 and an irradiance E=0.5Wm−2 were found to be suitable parameters for an analysis of the disinfection rate as a function of τ=0.5–10ms and fp=25–500Hz unveiling that shorter pulses and lower frequencies inactivate more spores. Finally, the number of applied pulses as well as the experiment time were considered with regard to spore film disinfection.

Experimental studies of degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solutions with high concentration of sodium nitrate under pulsed broadband ultraviolet radiation

Experimental studies of degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solutions with high concentration of sodium nitrate under pulsed broadband ultraviolet radiation

Vitamin D production in psoriasis patients increases less with narrowband than with broadband ultraviolet B phototherapy

Phototherapy of psoriasis is an effective treatment. In addition to standard broadband ultraviolet radiation B (UVB), (280-320 nm), narrowband phototherapy (NBUVB) (monochromatic UV between 311 and 312 nm) has become an important treatment for psoriasis. The same wavelength range of UVB (290-315 nm) induces synthesis of vitamin D. The aim was to compare the effect of broadband with NBUVB therapy on vitamin D synthesis in patients with psoriasis. Sixty-eight Caucasian patients (17 women and 51 men) mean age 54.1 +/- 16.0 years, with active plaque psoriasis, were treated with broadband UVB (n=26) or NBUVB (n=42) two to three times/week for 8-12 weeks. The serum concentrations of 25-hydroxyvitamin D (25(OH)D3), 1,25-dihydroxyvitamin D (1,25(OH)(2)D3), intact parathyroid hormone (PTH), calcium and creatinine were measured before the first exposure and after the last dose of radiation. In broadband UVB treated patients, 25(OH)D3 increased from 37.9 +/- 16.9 to 69.4 +/- 19.7 ng/ml (P<0.0001) and in patients treated with NBUVB from 34.8 +/- 11.9 to 55.3 +/- 17.6 ng/ml (P<0.0001) and P=0.008 between the treatment groups. PTH decreased on broadband UVB (P<0.05). The serum concentrations of 1,25(OH)(2)D3, calcium or creatinine remained unaltered. Serum 25(OH)D3 in psoriasis patients increased less with NBUVB than with broadband UVB phototherapy. Psoriasis improved on both regimens.

Effects of selenium compounds on induction of DNA damage by broadband ultraviolet radiation in human keratinocytes.

Background Ultraviolet radiation (UVR), a ubiquitous environmental genotoxin for the skin, produces DNA damage. The trace element selenium induces synthesis of the glutathione peroxidase and thioredoxin reductase enzyme families. These selenoenzymes detoxify a range of toxic compounds generated by free radicals. Objectives To assess the effects of pretreatment of primary human keratinocytes with selenium on UVR-induced DNA damage. Methods Cells were irradiated with UVR from FS-20 lamps and were subjected to comet assay. Results Comet tail length due to UVR-induced T4 endonuclease V-sensitive sites (caused by cyclopyrimidine dimers, CPDs) increased to 35 +/- 4.5 microm (mean +/- SD) immediately after irradiation (time 0 h, 100%). After 4 h, 68% of the damage remained and after 24 h, 23% of the damage was still present. Treatment with up to 200 nmol L-1 selenomethionine or 50 nmol L-1 sodium selenite had no effect on CPD formation or rates of repair, or on the number of excision repair sites as measured by cytosine arabino furanoside and hydroxyurea treatment. However, selenite and selenomethionine protected against oxidative damage to DNA as measured by formation of formamidopyrimidine (FaPy) glycosylase-sensitive sites, which are indicative of 8-hydroxy-2-deoxyguanosine photoproduct formation. In this assay, irradiation of keratinocytes increased mean +/- SD glycosylase-specific comet tail length from 5 +/- 1.5 microm to 19 +/- 3.3 microm. Preincubation for 18 h with 50 nmol L-1 selenite abolished the UVR-induced increase in comet length. Preincubation with 200 nmol L-1 selenomethionine was similarly protective. Conclusions Selenite and selenomethionine protect keratinocytes from UVR-induced oxidative damage, but not from formation of UVR-induced excision repair sites.

Ultraviolet absorption and fluorescence measurements in turbulent spray flames

Studies of elemental and organic carbon formation/oxidation in diffusion or rich premixed combustion systems focus mostly on soot particles and polycyclic aromatic hydrocarbons. In recent years, a new class of carbon compounds, in the form of molecular clusters (nanoparticles) of organic composition has been inferred, detected, and modeled within and at the exhausts of a variety of combustion systems. This new category of pollutants seems to be related to the formation processes of ultrafine particles found at the exhaust of practical combustion systems, which are considered dangerous to human health. Heavy molecular weights and extremely small sizes of nanoparticles prevent their detection by ordinary techniques (e.g., GC-MS), particularly in combustion conditions. The paper reports on optical investigations based on ultraviolet (UV) extinction spectroscopy and laser-induced fluorescence (LIF) of turbulent flames and exhausts of a spray burner, involving processes by far more complex than gaseous laminar flames. The light source for extinction was the plasma emission, resulting from the optical breakdown of a Q-switched Nd:YAG laser pulse, which featured intense, fast, and bright broadband UV radiation. Extinction spectra in the UV band range of 200–500 nm and LIF UV-visible spectra, excited at λ=266 nm, were measured and analyzed at different heights above the nozzle, which allowed us to infer the formation/oxidation of species strongly absorbing in the far UV region and fluorescing at longer wavelengths. Resulting data were correlated with the spectral extinction of air-diluted exhausts.

Intercomparison of Effective Erythemal Irradiance Measurements from Two Types of Broad‐Band Instruments during June 1995

The biologically effective global solar ultraviolet radiation (UVR) measurements from a multiband UVR monitor and a conventional broadband UVR monitor are compared. The measurements were performed during the varied weather conditions of June 1995. We compared the daily total exposures measured by both instruments, as well as the ratio of the measured doses throughout the course of each day. The daily total exposures agreed within approximately 11% throughout the month. The ratio between the measured doses held at 1.12 between 0900 and 1700 h (solar zenith angles approximately 16-52 degrees). The ratio decreased from 1.12 to 0.90 during the next 90 min outside that period (solar zenith angles approximately 52-72 degrees) and decreased further beyond that point. Spectral response and cosine response mismatch between the instruments are discussed as the possible cause of discrepancies between the measured doses. Implications for erythemal irradiance monitoring and suggestions for further study are discussed.

Erythemally Effective and Actinic Irradiance from a Tungsten Halogen Lamp

A protocol for assessment of biological hazard from ultraviolet radiation sources was developed. The protocol utilized both a ultraviolet radiation spectroradiometer and a broadband ultraviolet radiation meter for the determination of the erythemally effective irradiance and the actinic irradiance. A 250 W tungsten halogen lamp operating at 9.5 A was tested with this protocol. It was found that the erythemally effective irradiance varied from 41 microW cm(-2) at 10 cm to 1.5 microW cm(-2) at 50 cm. In the same range of distances, the actinic irradiance decreased from 23 to 0.5 microW cm(-2). The irradiance from the source was uniform within 30 degrees about the line perpendicular to the axis of the filament. Using the recommendation of the Australian radiation protection agency, the National Health and Medical Research Council, the maximum allowable exposure time at the distance of 50 cm in the direction perpendicular to the axis of the filament was about 33.3 minutes.

Flash photolysis of iodides in the presence of quenching gases. III. Photolysis of C3F7OI

The quenching buffer method was used in measurements of the rate constants of the principal reactions involved in flash photolysis of the iodide C3F7OI (RI) and of its mixtures with buffer gases M (CF3H, H2O): R+R → R2; R+I → RI; I*+RI, M, I2 → I+RI, M, I2; I + I + RI, M → I2 + RI, M. The broadening coefficients were determined for the line due to the active transition in a photodissociation laser when the broadening was due to collisions with C3F7OI, CF3H, and H2O molecules. The probabilities of formation of excited iodine atoms by photodissociation of the iodides C2F5I and C3F7OI with broadband ultraviolet radiation were also found. The low recombination efficiency (found for the iodides investigated earlier) was confirmed for the C2F5 and C3F7O radicals interacting with excited iodine atoms.

Pitfalls in the in vitro determination of sunscreen protection factors using broad band ultraviolet radiation detectors and solar simulating radiation

Synopsis Reliable in vitro techniques for assessing sunscreen protection factors have relied upon obtaining the forward scattering transmission spectrum of the test compound applied to a suitable substrate such as mouse or human epidermis. A theoretical analysis of alternative techniques using broad-band ultraviolet radiation detectors in conjunction with a source of simulated sunlight shows that the method is likely to yield unreliable values of sun protection factors and the reasons for this are discussed.

Matrix photochemistry of hypofluorous acid, HOF: oxygen atom transfer and other reactions

The infrared spectrum of the hypofluorous acid molecule, HOF, trapped in different solid matrices at low temperatures shows that the vibrational fundamentals {nu}{sub 1} and {nu}{sub 2} are perturbed to extents that vary with the basicity of the adjacent molecule, D, and the appearance of absorptions attributable to librational motions of the D{hor ellipsis}H-OF unit implies the formation of specific hydrogen-bonded complexes in some cases. As the matrix concentration of HOF increases, aggregation occurs to give (HOF){sub 2} and higher multimers. Exposure of HOF isolated in an Ar matrix to broad-band ultraviolet radiation results in photodissociation with the formation of two products thought to be O{hor ellipsis}(HF){sub 2} and O{sub 2}{hor ellipsis}(HF){sub 2} in proportions dependent on the concentration of HOF. Photolysis of HOF trapped in a reactive matrix results in oxygenation of the matrix molecules, X, and complexation of the product XO by HF; e.g. X = N{sub 2}, CO, O{sub 2}, or CH{sub 4}. The CO, O{sub 2}, or CH{sub 4} matrices also yield on photolysis small but significant amounts of FCO{sup {sm bullet}}, O{sub 2}F{sup {sm bullet}}, or CH{sub 3}{hor ellipsis}HF, respectively, products that signal the intervention of fluorine atoms. Photolysis of an Ar matrix including HOFmore » together with a potential substrate, Y, at concentrations > 1% results exclusively in oxygenation, and not fluorination, to give YO (Y = PF{sub 3}, AsF{sub 3}, or H{sub 2}O). The results are discussed in relation to the mechanisms likely to govern the matrix photochemistry of HOF.« less

Beauty Today and Youth Tomorrow?

As demonstrated by the simultaneous proliferation of tanning salons and a tremendous growth in interest in new agents that may reverse photoaging or at least wrinkles that accompany tanning, many people want both.1In this month'sArchives of Dermatology, Bech-Thomsen and colleagues2present provocative data suggesting that in hairless mice, preirradiation with long-wave (A range) ultraviolet radiation (UV-A), similar to the wavelengths emitted by most tanning salon units, provides significant protection against the development of skin tumors in mice subsequently exposed to broad-band ultraviolet radiation (ie, the sun). These well-designed experiments suggest that, at least in the hairless mouse, a brief visit to a tanning parlor before exposure to the sun (ie, both sunburn-spectrum [B range] ultraviolet radiation [UV-B] and UV-A) might help reduce the risk of sun-induced nonmelanoma skin cancer. Somewhat surprisingly, the authors do not relate this apparent protective effect of preirradiation to increases in skin