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Results for “ULTRAVIOLET RADIATION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Effect of Prolonged Ultraviolet Radiation Exposure on the Blast Response of Fiber Reinforced Composite Plates

An experimental study with corresponding numerical simulations was conducted to evaluate the blast response of composite plates after prolonged exposure to ultraviolet radiation. Two composite materials were used in this study, namely carbon fiber/epoxy and glass fiber/vinyl ester. The composite materials consisted of four unidirectional fiber plies oriented in a [± 45°]s layup. The plates were placed in a QUV Accelerated Weathering Tester for 500 h of exposure on each face, totaling 1000 h of ultraviolet radiation exposure, equivalent to 2.5 MJ/m{sup 2} of energy. The QUV Accelerated Weathering Tester was equipped with eight UVA-340 lamps to provide real service life exposure conditions. Material characterization experiments were performed on virgin specimens, as well as specimens exposed to ultraviolet radiation for 1000 h to determine its effect on the mechanical properties of the composites. Blast experiments were conducted on the composite plates to investigate the dynamic response before and after exposure to ultraviolet radiation. The plates were clamped on all edges and subjected to an air blast using a shock tube apparatus. Three-dimensional digital image correlation was coupled with high-speed photography to obtain full-field displacements of the specimens during blast loading. Furthermore, three piezoelectric pressure transducers were mounted on the shock tube apparatus and utilized to measure the pressure history of the shock wave loading. The quasi-static material characterization showed that the tensile modulus E{sub 1} had minimal change after exposure to ultraviolet radiation for 1000 h. However, matrix-dominated properties such as the in-plane shear modulus G{sub 12} increased after exposure to ultraviolet light for both the carbon and glass fiber composites, which resulted in lower out-of-plane displacements during blast loading. For the carbon fiber plates, the forced vibration frequency induced by the transverse blast load was higher in plates exposed to ultraviolet radiation when compared to virgin specimens. However, for the glass fiber plates exposed to ultraviolet radiation, the forced vibration frequency decreased when compared to virgin specimens. Finally, the finite element simulations were in good agreement with the experimental results. The simulations revealed that the glass fiber plates exposed to ultraviolet radiation had higher failure strains at the boundary than virgin specimens, despite having higher stiffness. A parametric study in which higher loading was simulated also showed that the glass fiber plates experienced more damage after 1000 h of ultraviolet radiation exposure.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Estimating Ultraviolet Radiation From Global Horizontal Irradiance

Terrestrial ultraviolet radiation (UV) radiation is a primary factor contributing to the degradation of photovoltaic (PV) modules' efficiency and reliability over time. Therefore, accurate knowledge of terrestrial UV incident on the surface of the PV materials is essential to understand the degradation of PV modules and provide reliable assessment of their service life. As PV is deployed in various climate zones, it is crucial that terrestrial UV information is available at various locations. However, the availability of terrestrial UV data - measured or modeled - is extremely limited. On the other hand, total solar irradiance (TS) datasets are relatively abundant. In this study, the National Renewable Energy Laboratory, its industry partners, and ASTM's International Subcommittee on Radiometry and Service Life Prediction are developing a simple method to estimate the clear-sky terrestrial UV irradiance (280-400 nm, 295-400 nm, 285-385 nm, or 295-385 nm) from total irradiance data (280-4000 nm). The goal is to provide reliable estimates of the UV received by samples as a function of location, orientation, tilt, and airmass, thus encompassing a variety of conditions. Here, the Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) model is used to estimate the UV:TS ratio under various scenarios, and examines the influences of atmospheric constituents, such as aerosols, precipitable water vapor or ozone, and of the local surface characteristics (albedo), on the predicted UV.

14 SOLAR ENERGY↗
DOE OSTI2018

Generation of coherent phonons by coherent extreme ultraviolet radiation in a transient grating experiment

In this work, 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 Bi 4 Ge 3 O 12 ; 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.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Escherichia coli tolerance of ultraviolet radiation by in vivo expression of a short peptide designed from late embryogenesis abundant protein

Highlights: • A peptide of late embryogenesis abundant (LEA) protein was expressed in E. coli. • LEA peptide expression was induced with IPTG in a concentration-dependent manner. • LEA peptide expression improved E. coli growth under ultraviolet radiation. • LEA peptide could be used to genetically modify organisms for ultraviolet resistance. Ultraviolet (UV) radiation causes damage in all living organisms, including DNA damage that leads to cell death. Herein, we provide a new technique for UV radiation protection through intracellular short peptide expression. The late embryogenesis abundant (LEA) peptide, which functions as a shield that protects macromolecules from various abiotic stress, was obtained from the Polypedilum vanderplanki group 3 LEA protein. Recombinant Escherichia coli BL21 (DE3) expressing functional LEA short peptide in vivo were exposed to UVA and UVC radiation for 4, 6, and 8 h. E. coli transformants expressing the LEA peptide showed higher cell viability under both UVA and UVC treatment at all time points as compared with that of the control. Furthermore, the cells expressing LEA peptide showed a higher number of colony-forming units per dilution under UVA and UVC treatment. These results suggested that expression of the short peptide could be useful for the development of genetically modified organisms and in applications that require resilience of organisms to UV radiation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

A Study of the Ultraviolet Radiation of Hybrid X-Pinches

The results of an experimental study of hybrid X-pinches (HXPs) as sources of vacuum ultraviolet (VUV) radiation within the wavelength range of λ < 2000 Å are presented here. A KING compact low-voltage generator (45 kV, 200 kA, 190 ns) was used to feed the X-pinches. The dynamics of forming the radiating plasma of HXPs of different materials were studied using pinhole cameras with radiation receivers based on microchannel plates with a time resolution of 5 ns and a spatial resolution of 150 µm. The time structure and energy characteristics of the radiation were studied using diamond photoconducting detectors (PCDs). The spectral composition of UV radiation was investigated using a spectrograph based on the transmission grating. It has been shown that the efficiency of conversion of the capacitor-stored energy to the VUV radiation may reach 5%, whereas the fraction of soft X-rays (SXR) with quanta energies above 800 eV is no more than 3%. In this case, the source brightness reaches 2 × 10 9 W/(sr cm 2 ).

plasma UV-spectroscopy↗
DOE OSTI2018

Two Methods of Amplification of Coherent Extreme Ultraviolet Radiation During Harmonic Generation in Plasmas

Different recently revealed approaches of harmonic enhancement in plasmas are reviewed. The 4-step analytical model of resonant enhancement of high-order harmonic generation is extended to the systems possessing resonant transitions of inner-shell electrons. Role of inelastic scattering is discussed by simulation of excited state’s population dynamics. The enhancement of harmonics in the In plasma using different pumps is analyzed to prove the concept. We also discuss the plasma emission and harmonic generation spectra in the case of resonance enhancement of single harmonic using various laser-produced plasmas. The analysis of these spectra showed that the enhancement of harmonics depended on the oscillator strengths of the nearby ionic transitions rather than the plasma emission transitions. Finally, we review some recent experimental studies of the phase-matching of high-order harmonic generation in multi-jet plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Redirection and reshaping of intense extreme-ultraviolet radiation

The goal to control short-wavelength radiation for the investigation and manipulation of ultrafast dynamics in quantum systems coevolves with the growing availability of extreme-ultraviolet (XUV) and x-ray sources from high-harmonic generation and free-electron lasers. Here, we present an XUV spatio-spectral phase modulator based on an intense XUV laser beam propagating through an optically thick resonant target, introducing dispersion profile variations around the resonance both perpendicular to and along the laser propagation direction. The resulting dipole radiation gets spectrally reshaped and becomes more divergent as compared to the original beam in the far field. As an experimental demonstration, the intense-XUV–induced double-peak off-axis structure in the far-field spectrum obtained at the Free-Electron Laser in Hamburg (FLASH) shows indications of the underlying XUV-driven Rabi dynamics and resonant pulse propagation effects. The presented work highlights a ubiquitous phenomenon occurring when an intense laser beam passes through a resonant medium.

He, Yu [Max-Planck-Institut für Kernphysik, Heidel↗
DOE OSTI2019

Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets around Low-mass Stars: The TRAPPIST-1 System

The high energy radiation environment around M dwarf stars strongly affects the characteristics of close-in exoplanet atmospheres, but these wavelengths are difficult to observe because of geocoronal and interstellar contamination. Due to these observational restrictions, a stellar atmosphere model may be used to compute the stellar extreme ultraviolet (EUV; 100–912 Å) spectrum. We construct semiempirical nonlocal thermodynamic equilibrium model spectra of the ultracool M8 star TRAPPIST-1 that span EUV to infrared wavelengths (100 Å-2.5 μm) using the atmosphere code PHOENIX. These upper atmosphere models contain prescriptions for the chromosphere and transition region and include newly added partial frequency redistribution capabilities. In the absence of broadband UV spectral observations, we constrain our models using Hubble Space Telescope Lyman α observations from TRAPPIST-1 and Galaxy Evolution Explorer UV photometric detections from a set of old M8 stars (>1 Gyr). We find that calibrating the models using both data sets separately yield similar far-ultraviolet and NUV fluxes, and EUV fluxes that range from (1.32–17.4) × 10 -14 ergs s -1 cm -2 . The findings from these models demonstrate that the EUV emission is very sensitive to the temperature structure in the transition region. Our lower activity models predict EUV fluxes similar to previously published estimates derived from semiempirical scaling relationships, while the highest activity model predicts EUV fluxes a factor of 10 higher. Results from this study support the idea that the TRAPPIST-1 habitable zone planets likely do not have much liquid water on their surfaces due to the elevated levels of high energy radiation emitted by the host star.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2021

Ultraviolet radiation pre-treatment of wastewater, improving its utility for algal cultivation

The present invention relates to a process of remediating wastewaters, preferably agricultural wastewaters resulting from animal production or contained animal feeding operation sites. The water is treated to promote assimilation of nutrients into algal biomass, which can be harvested and sold, and the resultant wastewater is then purified. According to the invention, short wavelength UV radiation (less than 280 nm wavelength) is used to pretreat wastewater, with the dose determined by absorbance of the water, not by bacterial load. Pretreated water exhibits changes in chromophoric dissolved organic matter that allows for improved and increased algae production by as much as 88%.

Feris, Kevin↗
DOE OSTI2024

Impact of ultraviolet-B radiation on early-season morpho-physiological traits of indica and japonica rice genotypes

Ultraviolet (UV)-B radiation is considered one of the major detrimental rays coming from the Sun. UV-B radiation has a harmful impact on plant growth and development. The effect of UV-B radiation was studied on 64 rice (Oryza sativa L.) genotypes during the vegetative season. An equal number of genotypes from the japonica (50%) and indica (50%) subspecies were phenotyped using the Soil-Plant-Atmosphere-Research (SPAR) units. The 10 kJ UV-B was imposed 12 days after planting (DAP) and continued for three weeks (21 d). Based on the combined ultraviolet-B radiation response index (CUVBRI) for each genotype, the 64 rice genotypes were classified into sensitive, moderately sensitive, moderately tolerant, and tolerant. Various shoot traits, such as plant height, tiller, and leaf numbers, were measured. We also studied critical root phenological traits like root volume, diameter, tips, and forks. Out of all the studied shoot traits, leaf area showed maximum reduction for both indica (54%) and japonica (48%). Among the root traits, root length decreased by negligible (1%) for indica as compared to japonica (5%), while root crossing and forks showed a maximum decline for japonica (37 and 42%), respectively. This study is timely, meaningful, and required because it will help breeders select a tolerant or sensitive rice line for better yield and production under abiotic stresses.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

RNA‐Seq analysis revealed the molecular mechanisms of photobiomodulation effect on human fibroblasts

Abstract Background The photobiomodulation (PBM) effect has been applied to various clinical therapy for a long time. However, the mechanism related to the PBM effect in terms of wavelengths has been lack of in‐depth study, except that ultraviolet radiation has attracted much attention due to its strong cell‐killing effect. Purpose To clarify the principle behind PBM and the main mechanism of improvement. Methods To carry on this study, we created light equipment using three LED chips, which emit 390 nm ultraviolet radiation, 415 nm blue light and 660 nm red light, respectively. We choose human fibroblasts (HF) to be irradiated by three different wavelengths for PBM test. In this study, we used cell counting kit (CCK‐8) test to show the cell proliferation roughly and reported on a systematic RNA sequencing (RNA‐seq) analysis at transcriptional expression levels from HF, which accepted PBM of different wavelengths of light. Results We found that 415 nm blue light inhibited cell proliferation and 660 nm red light stimulated cell proliferation while 390 nm ultraviolet radiation has little influence on cell proliferation. Furthermore, RNA‐seq results showed that CSF1R, PPP3CC, ITGAL, ITGAM, IL2RB, and several other differentially expressed genes (DEGs) are involved in the cell proliferation. Relative DEGs values for matrix metalloproteinases (MMPs) gene family have shown a great difference in blue and red light radiation especially on MMP25, MMP9, MMP21, and MMP13. Conclusion Taken together, the results provide a valuable resource to describe the variation of HFs under PBM of different light at gene level.

Li, Wenqi↗
DOE OSTI2023

Stratospheric ozone depletion in the Antarctic region triggers intense changes in sea salt aerosol geochemistry

Abstract Since the early 1980s, the Antarctic environment has served as a natural field laboratory for researchers to investigate the effects of stratospheric ozone depletion, which has resulted in increased surface ultraviolet radiation levels. However, its effective threats still present gaps. We report new pieces of evidence of increased ultraviolet radiation impacting West Antarctica sea salt aerosols. Salt aerosols, particularly in the Southern Ocean Sea, play an important role in the radiative earth balance. To disclose the molecular details of sea salt aerosols, we used a synchrotron-based multi-element microscopic speciation of individual microparticles (Scanning Transmission X-ray Microscopy with Near-Edge X-ray Absorption Fine Structure Spectroscopy combined with Computer-Controlled Scanning Electron Microscopy). Here we identified substantial abundances of chlorine-enriched aerosols in sea salt generated by photolytic products, whereas ice core records revealed increased chlorine depletion from the onset of ozone depletion. Our findings reveal that modern sea salt modification has no Holocene precedent.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Demonstration of a ring-FEL as an EUV lithography tool

In this work, we present the required structure and function of a ring-FEL as a radiation source for extreme ultraviolet radiation lithography (EUVL). A 100 m-long straight section that conducts an extremely low emittance beam from a fourth-generation storage ring can increase the average power at 13.5 nm wavelength to up to 1 kW without degrading the beam in the rest of the ring. Here, simulation results for a ring-FEL as a EUVL source are described.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2018

On the Fabrication of Graphene p–n Junctions and Their Application for Detecting Terahertz Radiation

A new method for the formation of lateral p–n junctions in epitaxial graphene with the use of UV (ultraviolet) radiation is considered. The UV illumination method makes it possible to obtain large-size p–n junctions. Such p–n junctions are investigated in the photocurrent and photoconductivity modes under irradiation with terahertz radiation. The mechanisms of terahertz photoresponse in graphene p–n junctions are discussed.

36 MATERIALS SCIENCE↗