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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Unveiling the Impact of Distinct Melanosome Arrangements on the Attenuation of Cancer-Inducing Ultraviolet Radiation
摘要： The exposure of human skin to ultraviolet radiation (UVR) can trigger a wide array of biological responses, including photocarcinogenesis. Melanin, either in colloidal form or encapsulated into melanosomes, is known to be the main UVR attenuation substance acting within the cutaneous tissues. Although many studies have addressed the protective role of this pigment against the harmful effects of UVR exposure, the impact of different melanosome arrangements on the mitigation of these effects remains to be quantitatively verified. The difficulties to resolve this open question can be mainly attributed to the intrinsic practical limitations of in vivo and in vitro experiments involving skin specimens. In this paper, we describe controlled in silico experiments that allowed us to overcome such limitations and provide quantitative evidence for the clarification of this question. Besides contributing to a more robust understanding of the physiological parameters associated with cutaneous UVR attenuation, our findings can be incorporated into the development of more effective strategies for the evaluation of individuals' susceptibility to UVR exposure. Such strategies are essential for the prevention of UVR-induced pathologies, particularly skin cancer.
关键词： melanosome,sieve and detour effects,ultraviolet radiation,melanin,predictive simulation,skin cancer
更新于2025-09-23 15:23:52
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Fluorescent Penetrant Testing by Means of Excilamps
摘要： The paper provides a brief review of modern sources of ultraviolet (UV) radiation used in fluorescent penetrant testing (FT). The differences in implementation of the method with different radiation sources (excilamps, mercury UV lamp and LED UV lamp) are revealed experimentally. It is shown that the XeCl excilamp is not inferior to other sources of UV radiation used in FT.
关键词： Penetrant testing,UV lamp,fluorescent method,LED UV flashlight,ultraviolet radiation,test sample,excilamp
更新于2025-09-23 15:22:29
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Reconstruction and analysis of erythemal UV radiation time series from Hradec Králové (Czech Republic) over the past 50 years
摘要： This paper evaluates the variability of erythemal ultraviolet (EUV) radiation from Hradec Králové (Czech Republic) in the period 1964–2013. The EUV radiation time series was reconstructed using a radiative transfer model and 10 additional empirical relationships with the root mean square error of 9.9 %. The reconstructed time series documented the increase in EUV radiation doses in the 1980s and the 1990s (up to 15 % per decade), which is linked to the steep decline in total ozone (10 % per decade). The changes of cloud cover were the major factor affecting the EUV radiation doses especially in the 1960s, 1970s, and at the beginning of the new millennium. The mean annual EUV radiation doses in the decade 2004–2013 declined by 5 %. The factors affecting the EUV radiation doses differed also according to the chosen integration period (daily, monthly, and annually): solar zenith angle was the most important for daily doses, cloud cover for their monthly means, and the annual means of EUV radiation doses were most influenced by total ozone column. The number of days with very high EUV radiation doses increased by 22 % per decade, the increase was statistically significant in all seasons except autumn. The occurrence of the days with very high EUV doses was influenced mostly by low total ozone column (82 % of days), clear-sky or partly cloudy conditions (74 % of days) and by increased surface albedo (19 % of days). The principal component analysis documented that the occurrence of days with very high EUV radiation doses was much affected by the positive phase of North Atlantic Oscillation with an Azores High promontory reaching over central Europe. In the stratosphere, a strong Arctic circumpolar vortex and also the meridional inflow of ozone-poor air from the south-west were favourable for the occurrence of days with very high EUV radiation doses. This is the first analysis of the relationship between the high EUV radiation doses and macro-scale circulation patterns, and therefore more attention should be given also to other dynamical variables that may affect the solar UV radiation on the Earth surface.
关键词： cloud cover,erythemal ultraviolet radiation,atmospheric circulation patterns,total ozone column,surface albedo
更新于2025-09-23 15:21:21
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Evaluation of a Ultraviolet B Light Emitting Diode (LED) for Producing Vitamin D <sub/>3</sub> in Human Skin
摘要： Aim: A commercially available light emitting diode (LED) that transmitted narrow band ultraviolet B (UVB) radiation was evaluated for its efficacy and efficiency to produce vitamin D3 in human skin. Materials and Methods: Human skin samples were obtained from surgical procedures. The LED had peak emission wavelength of 295 nm. Skin samples were exposed to the UVB-LED for varying times and then were analyzed by high-pressure liquid chromatography (HPLC) to determine the vitamin D3 content. Results: There was a statistically significant time- and dose- dependent increase in the percent of 7-dehydrocholesterol that was converted to vitamin D3 in the skin type II samples; 1.3%±0.5, 2.3%±0.6 and 4.5%±1.67 after exposure to 0.75 (11.7 mJ/cm2), 1.5 (23.4 mJ/cm2) and 3 (46.8 mJ/cm2) minimal erythemal doses (MEDs), respectively. Conclusion: The UVB-LED was effective and efficient in generating vitamin D3 in human skin, in vitro. The amount of vitamin D3 production increased in a dose-dependent fashion with increased UVB energy. UVB-LEDs can be developed for devices that can efficiently produce vitamin D3 in human skin.
关键词： vitamin D3,human skin,ultraviolet B radiation,Previtamin D3,ultraviolet radiation light emitting diode (LED)
更新于2025-09-23 15:21:01
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A Wearable UV Sensor Based on Carbon Nanotube Coated Cotton Thread
摘要： A fabric-compatible UV sensor is presented using a cellulose-based thread coated with single wall carbon nanotube ink. Two-terminal resistive responses of the thread were measured upon exposure to UV, and the effects of intensity, wavelength and on/off cycling were studied. The sensor was tested in the field under direct sunlight, demonstrating practical usability for a wearable/flexible UV sensor system. The results here confirm the potential for an inexpensive wearable sensor in contrast to the conventional rigid and bulky solid state detectors.
关键词： cellulose thread,wearable ultraviolet sensor,ultraviolet radiation,oxygen desorption-adsorption,single wall carbon nanotube
更新于2025-09-23 15:21:01
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All 3D Printed Flexible ZnO UV Photodetector on Ultraflat Substrate
摘要： An all 3D printed flexible ZnO ultraviolet (UV) photodetector is demonstrated, where the 3D printing method is used not only for the electrode and photosensitive material but also for creating a substrate. An ultra-flat and flexible substrate capable of serving as the backbone layer is developed using a water-dissolvable polymer layer for surface planarization. A two layered printing followed by surface treatment is demonstrated for the substrate preparation. As a mechanical support but flexible, a thick and sparse thermoplastic polyurethane layer is printed. On its surface, a thin and dense polyvinyl alcohol (PVA) is then printed. A precise control of PVA reflow using micro-water droplet results in a flexible and extremely uniform substrate. A Cu-Ag nanowire network is directly 3D-printed on the flexible substrate for the conducting layer, followed by ZnO for photosensitive material. Unlike the planar two-dimensional printing that provides thin films, 3D printing allows the electrode to have a step height, which can be made like a dam to accommodate a thick film of ZnO. Photosentivity as a function of various ZnO thickness values was investigated to establish an optimal thickness for UV response. The device was also tested in natural sunlight along with stability and reliability.
关键词： ultraviolet radiation,UV detector,UV sensor,Printed electronics,3D printing,additive manufacturing
更新于2025-09-23 15:21:01
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Characterizing the transformation of aquatic humic substances exposed to ultraviolet radiation using excitation–emission matrix fluorescence spectroscopy and PARAFAC
摘要： It is important to understand the change in aquatic humic substances (AHS) induced by light due to the upward trend in ultraviolet (UV) radiation reaching the surface of the Earth. Changes in the quantity and quality of AHS in AHS-rich wetland water exposed to UV-A or UV-B light were determined using 3-dimensional excitation–emission matrix (EEM) fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) and a resin isolation method. The dissolved organic carbon and AHS-carbon concentrations decreased via photodegradation with UV-A or UV-B exposure. The decreases in both carbon concentrations were greater when exposed to UV-B than when exposed to UV-A. Three AHS-like components were detected by EEM-PARAFAC: AHS-1, AHS-2, and AHS-3. AHS-1 and AHS-3 were degraded more by UV-A and UV-B exposure, respectively. AHS-2 was degraded slightly by UV-A exposure, whereas exposure to UV-B generated AHS-2 in the presence of low-molecular-weight compounds, and then underwent photodegradation. AHS-1 exposed to UV-A and AHS-3 exposed to UV-A or UV-B photoflocculated at day 14. The humification index indicated that UV-A exposure led to the preferential photodegradation of AHS, whereas UV-B exposure not only caused AHS degradation but also the degradation or photoflocculation of other compounds with simple structures. AHS changed little in the dark, demonstrating that bacterial effects on AHS were relatively unimportant. The processes of humification and flocculation are important in removing and sequestering carbon from its active cycle. Therefore, the degradation and transformation of AHS exposed to UV can have a major impact on aquatic ecosystem processes.
关键词： photochemical degradation,ultraviolet radiation,aquatic humic substances (AHS),EEM-PARAFAC,dissolved organic matter (DOM)
更新于2025-09-23 15:21:01
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Generation of coherent phonons by coherent extreme ultraviolet radiation in a transient grating experiment
摘要： We investigate the excitation of coherent acoustic and optical phonons by ultrashort extreme ultraviolet (EUV) pulses produced by a free electron laser. Two crossed femtosecond EUV (wavelength 12.7 nm) pulses are used to excite coherent phonons at a wavelength of 280 nm, which are detected via diffraction of an optical probe beam. Longitudinal and surface acoustic waves are measured in BK-7 glass, diamond, and Bi4Ge3O12; in the latter material, the excitation of a coherent optical phonon mode is also observed. We discuss probing different acoustic modes in reflection and transmission geometries and frequency mixing of surface and bulk acoustic waves in the signal. The use of extreme ultraviolet radiation will allow the creation of tunable GHz to THz acoustic sources in any material without the need to fabricate transducer structures.
关键词： transient grating experiment,optical phonons,acoustic waves,extreme ultraviolet radiation,coherent phonons
更新于2025-09-23 15:21:01
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Measurement of UV radiation in commercial aircraft
摘要： Ultraviolet Radiation (UVR) is significantly higher at aviation altitudes with respect to sea level due to weaker attenuation by the atmosphere. At higher flight levels clear sky conditions cause permanent direct sunlight during the daytime hours. The transmittance of cockpit windshields and the UVR exposure of pilots have become subject of research due to the association of UVR with cataracts, carcinoma, melanoma and accelerated skin aging. In this work, the spectral properties of several windshields under flight conditions are investigated. Only one of the investigated windshields showed good UV-A attenuation. Furthermore, the altitude dependence of UV-A irradiance behind a windshield was measured with high spatial resolution. Measurements of the maximal UV irradiance behind the windshield surfaces and at the pilot’s position are compared to the recommendations by the International Commission on Non-Ionizing Radiation Protection. Some recommended limits were exceeded at the surface of the windshields with direct sunlight and a large field of view. At the pilot’s position, with a more realistic field of view, the unweighted recommended level could have been exceeded within tens of minutes by looking in the direction of the Sun without visor or other protective measures. The weighted recommended maximal UVR exposure was not exceeded, neither with the use of the visor at the pilot’s position nor without it. The use of the visor for filtering direct sunlight was very effective in terms of UV-A reduction.
关键词： Aircraft Windshield,Aviation,Ultraviolet Radiation
更新于2025-09-23 15:21:01
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UV-induced macromolecular and optical modifications in gelatin solid films with transition metal chlorides
摘要： Gelatin solid films containing transition metal chlorides (NiCl2·6H2O, CoCl2·6H2O and CrCl3.6H2O) were prepared and UV-irradiated at different exposure times, to study the effect of irradiation on the structural properties at the molecular level, as well as the electronic level, using FT-IR and UV-visible spectroscopies. Results showed that modifications in the molecular and electronic structure due to UV-irradiations were possible even when applying the irradiation treatment to the films in the solid phase. These modifications also differ according to the additive’s type and concentration. The force constant of the CO bond tends to increase, and that for the OH bond tends to decrease, by increasing the irradiation exposure time. The colour difference tends to have higher values for the films with the higher additive concentration and higher exposure times, in the meantime, the brightness tends to increase for Gelatin-NiCl2 and Gelatin-CrCl3 films, and decrease for Gelatin-CoCl2 films. The samples of the Gelatin-NiCl2 group become more yellowish and more greenish by increasing concentrations and exposure times, whereas those of the Gelatin-CoCl2 group tend to become more bluish and more reddish. Moreover, the values of yellowness tend to increase for Gelatin-CoCl2 and Gelatin-NiCl2 films with increasing concentrations and exposure times. Our research concludes that UV-induced modifications in the microstructure and optical properties of the gelatin films are possible in the solid phase due to increasing the crosslinking effects. With the current findings, these films can be used as radiation biosensors.
关键词： UV-vis spectroscopy,Ultraviolet radiation,Transition metals,gelatin,macrostructure,FT-IR
更新于2025-09-19 17:15:36