A comparison of UV surface brightness and HI surface densities for spiral galaxies

International Nuclear Information System (INIS)

Federman, S.R.; Strom, C.

1990-01-01

Shaya and Federman (1987) suggested that the ambient ultraviolet flux at 1000 A permeating a spiral galaxy controls the neutral hydrogen (HI) surface density in the galaxy. They found that the atomic envelopes surrounding small molecular clouds, because of their great number, provide the major contribution to the HI surface density over the stellar disk. The increase in HI surface density with later Hubble types was ascribed to the stronger UV fields from more high-mass stars in later Hubble types. These hypotheses are based on the observations of nearby diffuse interstellar clouds, which show a sharp atomic-to-molecular transition (Savage et al. 1977), and on the theoretical framework introduced by Federman, Glassgold, and Kwan (1979). Atomic envelopes around interstellar clouds in the solar neighborhood arise when a steady state is reached between photodissociation of H2 and the formation of H2 on grains. The photodissociation process involves photons with wavelengths between 912 A and 1108 A. Shaya and Federman used H-alpha flux as an approximate measure for the far UV flux and made their comparisons based on averages over Hubble type. Here, researchers compare, on an individual basis, UV data obtained with space-borne and balloon-borne instruments for galaxies with measurements of HI surface density (Warmels 1988a, b). The comparisons substantiate the conclusion of Shaya and Federman that the far UV field controls the HI content of spiral galaxies

Extensive reduction of surface UV radiation since 1750 in world's populated regions

Directory of Open Access Journals (Sweden)

M. M. Kvalevåg

2009-10-01

Full Text Available Human activity influences a wide range of components that affect the surface UV radiation levels, among them ozone at high latitudes. We calculate the effect of human-induced changes in the surface erythemally weighted ultra-violet radiation (UV-E since 1750. We compare results from a radiative transfer model to surface UV-E radiation for year 2000 derived by satellite observations (from Total Ozone Mapping Spectroradiometer and to ground based measurements at 14 sites. The model correlates well with the observations; the correlation coefficients are 0.97 and 0.98 for satellite and ground based measurements, respectively. In addition to the effect of changes in ozone, we also investigate the effect of changes in SO₂, NO₂, the direct and indirect effects of aerosols, albedo changes and aviation-induced contrails and cirrus. The results show an increase of surface UV-E in polar regions, most strongly in the Southern Hemisphere. Furthermore, our study also shows an extensive surface UV-E reduction over most land areas; a reduction up to 20% since 1750 is found in some industrialized regions. This reduction in UV-E over the industrial period is particularly large in highly populated regions.

Facile Dry Surface Cleaning of Graphene by UV Treatment

Science.gov (United States)

Kim, Jin Hong; Haidari, Mohd Musaib; Choi, Jin Sik; Kim, Hakseong; Yu, Young-Jun; Park, Jonghyurk

2018-05-01

Graphene has been considered an ideal material for application in transparent lightweight wearable electronics due to its extraordinary mechanical, optical, and electrical properties originating from its ordered hexagonal carbon atomic lattice in a layer. Precise surface control is critical in maximizing its performance in electronic applications. Graphene grown by chemical vapor deposition is widely used but it produces polymeric residue following wet/chemical transfer process, which strongly affects its intrinsic electrical properties and limits the doping efficiency by adsorption. Here, we introduce a facile dry-cleaning method based on UV irradiation to eliminate the organic residues even after device fabrication. Through surface topography, Raman analysis, and electrical transport measurement characteristics, we confirm that the optimized UV treatment can recover the clean graphene surface and improve graphene-FET performance more effectively than thermal treatment. We propose our UV irradiation method as a systematically controllable and damage-free post process for application in large-area devices.

Effect of remote clouds on surface UV irradiance

Energy Technology Data Exchange (ETDEWEB)

Deguenther, M.; Meerkoetter, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

2000-06-01

Clouds affect local surface UV irradiance, even if the horizontal distance from the radiation observation site amounts to several kilometers. In order to investigate this effect, which we call remote clouds effect, a 3-dimensional radiative transfer model is applied. Assuming the atmosphere is subdivided into a quadratic based sector and its surrounding, we quantify the influence of changing cloud coverage within this surrounding from 0% to 100% on surface UV irradiance at the sector center. To work out this remote clouds influence as a function of sector base size, we made some calculations for different sizes between 10 km x 10 km and 100 km x 100 km. It appears that in the case of small sectors (base size {<=}20 km x 20 km) the remote clouds effect is highly variable: Depending on cloud structure, solar zenith angle and wavelength, the surface UV irradiance may be enhanced up to 15% as well as reduced by more than 50%. In contrast, for larger sectors it is always the case that enhancements become smaller by 5% if sector base size exceeds 60 km x 60 km. However, these values are upper estimates of the remote cloud effects and they are found only for special cloud structures. Since these structures might occur but cannot be regarded as typical, different satellite observed cloud formations (horizontal resolution about 1 km x 1 km) have also been investigated. For these more common cloud distributions we find remote cloud effects to be distinctly smaller than the corresponding upper estimates, e.g., for a sector with base size of 25 km x 25 km the surface UV irradiance error due to ignoring the actual remote clouds and replacing their influence with periodic horizontal boundary conditions is less than 3%, whereas the upper estimate of remote clouds effect would suggest an error close to 10%. (orig.)

Hyperspectral Surface Analysis for Ripeness Estimation and Quick UV-C Surface Treatments for Preservation of Bananas

Science.gov (United States)

Zhao, W.; Yang, Zh.; Chen, Zh.; Liu, J.; Wang, W. Ch.; Zheng, W. Yu.

2016-05-01

This study aimed to determine the ripeness of bananas using hyperspectral surface analysis and how a rapid UV-C (ultraviolet-C light) surface treatment could reduce decay. The surface of the banana fruit and its stages of maturity were studied using a hyperspectral imaging technique in the visible and near infrared (370-1000 nm) regions. The vselected color ratios from these spectral images were used for classifying the whole banana into immature, ripe, half-ripe and overripe stages. By using a BP neural network, models based on the wavelengths were developed to predict quality attributes. The mean discrimination rate was 98.17%. The surface of the fresh bananas was treated with UV-C at dosages from 15-55 μW/cm2. The visual qualities with or without UV-C treatment were compared using the image, the chromatic aberration test, the firmness test and the area of black spot on the banana skin. The results showed that high dosages of UV-C damaged the banana skin, while low dosages were more efficient at delaying changes in the relative brightness of the skin. The maximum UV-C treatment dose for satisfactory banana preservation was between 21 and 24 μW/cm2. These results could help to improve the visual quality of bananas and to classify their ripeness more easily.

Surface contamination to UV-curable acrylates in the furniture and parquet industry.

Science.gov (United States)

Surakka, J; Lindh, T; Rosén, G; Fischer, T

2001-03-01

Surface contamination to ultraviolet radiation curable coatings (UV coatings), used increasingly in the parquet and furniture industry, is a matter of concern as a source for skin contamination. UV coatings contain chemically and biologically reactive acrylates, well known as skin contact irritants and sensitizers. Surface contamination may spread secondarily to equipment and other unexpected areas even outside the workplace. Yet, studies concerning this type of contamination are lacking due to lack of suitable sampling methods. Surface contamination of the work environment with risk for skin exposure to UV coating was measured employing a quantitative adhesive tape sampling method developed for this purpose. A pilot study was first performed at three workplaces to evaluate the contamination. In the main study, we wanted to locate and identify in detail the surface contamination of areas where problems exist, and to determine the extent of the problem. Measurements were performed at seven workplaces on two separate workdays (round 1 and 2) within a six-month period. Samples were collected from the workplaces based on the video monitoring of skin contact frequency with the surfaces and categorized into three groups to analyze risk. The pilot study indicated that surface contamination to TPGDA containing UV coatings was common, found in 76 percent of the surfaces, and varied with a maximum of 909 microg TPGDA 10 cm(-2) sampling area. In the main study TPGDA was found in 153 out of 196 collected samples (78.1%); for round one 78.1 percent (82 out of 105 samples) and for round two 78.0 percent (71 out of 91 samples). The average TPGDA mass on positive surface samples was on the first round 2,247 +/- 7,462 microg, and on the second round 2,960 +/- 4,590 microg. We conclude that surface contamination to uncured UV coatings at UV-curing lines is common and this involves a risk for harmful, unintentional skin exposure to acrylates.

Estimation of surface UV levels based on Meteor-3/TOMS ozone data

Energy Technology Data Exchange (ETDEWEB)

Borisov, Y A [Central Aerological Observatory, Moscow (Russian Federation); Geogdzhaev, I V [Moscow Inst. of Physics and Technology, Moscow (Russian Federation); Khattatov, V U [Central Aerological Observatory, Moscow (Russian Federation)

1996-12-31

The major consequence of ozone layer depletion for the environment is an increase of harmful ultraviolet (UV) radiation on the Earth surface and in the upper ocean. This implies the importance of environmental UV monitoring. Since the direct global monitoring is not currently possible, indirect estimations of surface UV levels may be used based on satellite ozone data (Madronich, S. 1992). Total Ozone Mapping Spectrometer (TOMS) on board the METEOR-3 satellite provided regular set of data for such estimates. During the time of its operation (August, 1991 - December, 1994) the instrument registered several ozone hole events over Antarctica, when ozone levels dropped by as much as 60 % from their unperturbed values. Probably even more alarming ozone depletions were observed over highly populated regions of middle latitudes of northern hemisphere. Radiative transfer modeling was used to convert METEOR-3/TOMS daily ozone values into regional and global maps of biologically active UV. Calculations demonstrate the effect on surface UV levels produced by ozone hole over Antarctica and ozone depletions over the territory of Russia (March, 1994). UV contour lines deviate from the normal appearance which is determined by growing southward solar elevation. UV contour lines are almost perpendicular to the ozone ones in the ozone depletions areas. The 30 % ozone depletion, over Siberia caused more than 30 % increase in noontime erythemal UV levels, which is equivalent to 10-15 degrees southward latitude displacement. Higher UV radiation increases were found in ozone hole over South America (October 1992) equivalent to about 20 degrees southward displacement

Estimation of surface UV levels based on Meteor-3/TOMS ozone data

Energy Technology Data Exchange (ETDEWEB)

Borisov, Y.A. [Central Aerological Observatory, Moscow (Russian Federation); Geogdzhaev, I.V. [Moscow Inst. of Physics and Technology, Moscow (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Moscow (Russian Federation)

1995-12-31

The major consequence of ozone layer depletion for the environment is an increase of harmful ultraviolet (UV) radiation on the Earth surface and in the upper ocean. This implies the importance of environmental UV monitoring. Since the direct global monitoring is not currently possible, indirect estimations of surface UV levels may be used based on satellite ozone data (Madronich, S. 1992). Total Ozone Mapping Spectrometer (TOMS) on board the METEOR-3 satellite provided regular set of data for such estimates. During the time of its operation (August, 1991 - December, 1994) the instrument registered several ozone hole events over Antarctica, when ozone levels dropped by as much as 60 % from their unperturbed values. Probably even more alarming ozone depletions were observed over highly populated regions of middle latitudes of northern hemisphere. Radiative transfer modeling was used to convert METEOR-3/TOMS daily ozone values into regional and global maps of biologically active UV. Calculations demonstrate the effect on surface UV levels produced by ozone hole over Antarctica and ozone depletions over the territory of Russia (March, 1994). UV contour lines deviate from the normal appearance which is determined by growing southward solar elevation. UV contour lines are almost perpendicular to the ozone ones in the ozone depletions areas. The 30 % ozone depletion, over Siberia caused more than 30 % increase in noontime erythemal UV levels, which is equivalent to 10-15 degrees southward latitude displacement. Higher UV radiation increases were found in ozone hole over South America (October 1992) equivalent to about 20 degrees southward displacement

UV irradiation assisted growth of ZnO nanowires on optical fiber surface

Energy Technology Data Exchange (ETDEWEB)

Gong, Bo; Shi, Tielin; Liao, Guanglan; Li, Xiaoping; Huang, Jie; Zhou, Temgyuan; Tang, Zirong, E-mail: zirong@mail.hust.edu.cn

2017-06-01

Highlights: • A new fabrication process combined a hydrothermal process with UV irradiation from optical fiber is developed. • The growth of ZnO nanowires is efficient in the utilization of UV light. • A novel hybrid structure which integrates ZnO nanowires on optical fiber surface is synthesized. • The UV assisted growth of ZnO nanowires shows preferred orientation and better quality. • A mechanism of growing ZnO nanowires under UV irradiation is proposed. - Abstract: In this paper, a novel approach was developed for the enhanced growth of ZnO nanowires on optical fiber surface. The method combined a hydrothermal process with the efficient UV irradiation from the fiber core, and the effects of UV irradiation on the growth behavior of ZnO nanowires were investigated. The results show that UV irradiation had great effects on the preferred growth orientation and the quality of the ZnO nanowires. The crystallization velocity along the c-axis would increase rapidly with the increase of the irradiation power, while the growth process in the lateral direction was marginally affected by the irradiation. The structure of ZnO nanowires also shows less oxygen vacancy with UV irradiation of higher power. The developed approach is applicable for the efficient growth of nanowires on the fiber surface, and the ZnO nanowires/optical fiber hybrid structures have great potentials for a wide variety of applications such as optical fiber sensors and probes.

Effect of UV/ozone treatment on the nanoscale surface properties of gold implanted polyethylene

Energy Technology Data Exchange (ETDEWEB)

Kisić, Danilo; Nenadović, Miloš [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade (Serbia); Štrbac, Svetlana [ICTM Institute of Electrochemistry, University of Belgrade, Njegoseva 12, 11001 Belgrade (Serbia); Adnadjević, Borivoj [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Rakočević, Zlatko, E-mail: zlatkora@vinca.rs [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade (Serbia)

2014-07-01

The effect of ultraviolet (UV) ozone treatment on the surface properties of gold implanted high density polyethylene (HDPE) was investigated at a nanoscale using Atomic Force Microscopy (AFM). HDPE samples were modified by the implantation of gold ions at a dose of 5 × 10{sup 15} ions/cm{sup 2}, using energies of 50, 100, 150, and 200 keV, and subsequently treated with UV/ozone. AFM surface topography images revealed that after UV/ozone treatment, the surface roughness of all Au/HDPE samples increased, while Power Spectral Density function increased only for samples implanted using higher energies, with a maximum for 150 keV. The chemical surface composition was homogenous in all cases, which was evidenced by the appearance of single peaks in the histograms obtained from the phase AFM images. For UV/ozone treated samples, the shift of the peaks positions in the histograms to the higher values of the phase lag with respect to untreated ones indicated the decrease of surface hardness. Besides, a significant change of fractal dimension of surface grains is observed after UV/ozone treatment.

Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

Directory of Open Access Journals (Sweden)

M. Hess

2008-07-01

Full Text Available A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.

Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

Science.gov (United States)

Hess, M.; Koepke, P.

2008-07-01

A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.

Are the surgeons safe during UV-A radiation exposure in collagen cross-linking procedure?

Science.gov (United States)

Shetty, Rashmi; Shetty, Rohit; Mahendradas, Padmamalini; Shetty, Bhujang K

2012-02-01

To quantify the effect of scattered UV-A radiation used in the collagen cross-linking (CXL) procedure and the amount of radiation reaching the surgeon and the surrounding area and to estimate the dampening effect by various protective devices. In this case series, 3 patients [aged 25-30 (±2.5) years] with keratoconus underwent a CXL procedure with UV-A light and riboflavin. Irradiance was measured using a spectrometer (Model USB2000; Ocean Optics, Inc) for various distances from the source, at various angles, and for different durations of radiation. The spectrometer was also used to measure the dampening effect produced by gown, latex gloves, and UV-protective glasses. Maximum UV-A radiation (1.4 × 10(-9) mW/cm(2)) was measured at 2 cm from the limbus, when the probe was held at a 45-degree angle to the floor. UV-A radiation reaching the surgeon's eye and the abdomen was 3.403 × 10(-11) and 2.36 × 10(-11) mW/cm(2), respectively. Gown, latex gloves, and UV-protective glasses showed dampening effects of 99.58%, 95.01%, and 99.73%, respectively. CXL appears to be a safe procedure with respect to UV-A radiation exposure to the surgeon. Further safety can be ensured by UV-protective devices.

Super Water-Repellent Fractal Surfaces of a Photochromic Diarylethene Induced by UV Light

Science.gov (United States)

Izumi, Norikazu; Minami, Takayuki; Mayama, Hiroyuki; Takata, Atsushi; Nakamura, Shinichiro; Yokojima, Satoshi; Tsujii, Kaoru; Uchida, Kingo

2008-09-01

Photochromic diarylethene forms super water-repellent surfaces upon irradiation with UV light. Microfibril-like crystals grow on the solid diarylethene surface after UV irradiation, and the contact angle of water on the surface becomes larger with increasing surface roughness with time. The fractal analysis was made by the box-counting method for the rough surfaces. There are three regions in the roughness size having the fractal dimension of ca. 2.4 (size of roughness smaller than 5 µm), of ca. 2.2 (size of roughness between 5-40 µm), and of ca. 2.0 (size of roughness larger than 40 µm). The fractal dimension of ca. 2.4 was due to the fibril-like structures generated gradually by UV irradiation on diarylethene surfaces accompanied with an increase in the contact angle. The surface structure with larger fractal dimension mainly contributes to realizing the super water-repellency of the diarylethene surfaces. This mechanism of spontaneous formation of fractal surfaces is similar to that for triglyceride and alkylketene dimer waxes.

TiO2 micro-nano-hybrid surface to alleviate biological aging of UV-photofunctionalized titanium.

Science.gov (United States)

Iwasa, Fuminori; Tsukimura, Naoki; Sugita, Yoshihiko; Kanuru, Rajita Kodali; Kubo, Katsutoshi; Hasnain, Hafiz; Att, Wael; Ogawa, Takahiro

2011-01-01

Bioactivity and osteoconductivity of titanium degrade over time after surface processing. This time-dependent degradation is substantial and defined as the biological aging of titanium. UV treatment has shown to reactivate the aged surfaces, a process known as photofunctionalization. This study determined whether there is a difference in the behavior of biological aging for titanium with micro-nano-hybrid topography and titanium with microtopography alone, following functionalization. Titanium disks were acid etched to create micropits on the surface. Micro-nano-hybrid surfaces were created by depositioning 300-nm diameter TiO(2) nodules onto the micropits using a previously established self-assembly protocol. These disks were stored for 8 weeks in the dark to allow sufficient aging, then treated with UV light for 48 hours. Rat bone marrow-derived osteoblasts were cultured on fresh disks (immediately after UV treatment), 3-day-old disks (disks stored for 3 days after UV treatment), and 7-day- old disks. The rates of cell attachment, spread, proliferation, and levels of alkaline phosphatase activity, and calcium deposition were reduced by 30%-50% on micropit surfaces, depending on the age of the titanium. In contrast, 7-day-old hybrid surfaces maintained equivalent levels of bioactivity compared with the fresh surfaces. Both micropit and micro-nano-hybrid surfaces were superhydrophilic immediately after UV treatment. However, after 7 days, the micro-nano- hybrid surfaces became hydrorepellent, while the micropit surfaces remained hydrophilic. The sustained bioactivity levels of the micro-nano-hybrid surfaces were nullified by treating these surfaces with Cl(-)anions. A thin TiO(2) coating on the micropit surface without the formation of nanonodules did not result in the prevention or alleviation of the time-dependent decrease in biological activity. In conclusion, the micro-nano-hybrid titanium surfaces may slow the rate of time-dependent degradation of titanium

Femtosecond UV-laser pulses to unveil protein-protein interactions in living cells.

Science.gov (United States)

Itri, Francesco; Monti, Daria M; Della Ventura, Bartolomeo; Vinciguerra, Roberto; Chino, Marco; Gesuele, Felice; Lombardi, Angelina; Velotta, Raffaele; Altucci, Carlo; Birolo, Leila; Piccoli, Renata; Arciello, Angela

2016-02-01

A hallmark to decipher bioprocesses is to characterize protein-protein interactions in living cells. To do this, the development of innovative methodologies, which do not alter proteins and their natural environment, is particularly needed. Here, we report a method (LUCK, Laser UV Cross-linKing) to in vivo cross-link proteins by UV-laser irradiation of living cells. Upon irradiation of HeLa cells under controlled conditions, cross-linked products of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were detected, whose yield was found to be a linear function of the total irradiation energy. We demonstrated that stable dimers of GAPDH were formed through intersubunit cross-linking, as also observed when the pure protein was irradiated by UV-laser in vitro. We proposed a defined patch of aromatic residues located at the enzyme subunit interface as the cross-linking sites involved in dimer formation. Hence, by this technique, UV-laser is able to photofix protein surfaces that come in direct contact. Due to the ultra-short time scale of UV-laser-induced cross-linking, this technique could be extended to weld even transient protein interactions in their native context.

UV laser-ablated surface textures as potential regulator of cellular response.

Science.gov (United States)

Chandra, Prafulla; Lai, Karen; Sung, Hak-Joon; Murthy, N Sanjeeva; Kohn, Joachim

2010-06-01

Textured surfaces obtained by UV laser ablation of poly(ethylene terephthalate) films were used to study the effect of shape and spacing of surface features on cellular response. Two distinct patterns, cones and ripples with spacing from 2 to 25 μm, were produced. Surface features with different shapes and spacings were produced by varying pulse repetition rate, laser fluence, and exposure time. The effects of the surface texture parameters, i.e., shape and spacing, on cell attachment, proliferation, and morphology of neonatal human dermal fibroblasts and mouse fibroblasts were studied. Cell attachment was the highest in the regions with cones at ∼4 μm spacing. As feature spacing increased, cell spreading decreased, and the fibroblasts became more circular, indicating a stress-mediated cell shrinkage. This study shows that UV laser ablation is a useful alternative to lithographic techniques to produce surface patterns for controlling cell attachment and growth on biomaterial surfaces.

UV cross-linking of polypeptides associated with 3'-terminal exons

International Nuclear Information System (INIS)

Stolow, D.T.; Berget, S.M.

1990-01-01

Association of nuclear proteins with chimeric vertebrate precursor RNAs containing both polyadenylation signals and an intron was examined by UV cross-linking. One major difference in cross-linking pattern was observed between this chimeric precursor RNA and precursors containing only polyadenylation or splicing signals. The heterogeneous nuclear ribonucleoprotein (hnRNP) polypeptide C cross-linked strongly to sequences downstream of the A addition site in polyadenylation precursor RNA containing only the polyadenylation signal from the simian virus 40 (SV40) late transcription unit. In contrast, the hnRNP C polypeptide cross-linked to chimeric RNA containing the same SV40 late poly(A) cassette very poorly, at a level less than 5% of that observed with the precursor RNA containing just the poly(A) site. Observation that cross-linking of the hnRNP C polypeptide to elements within the SV40 late poly(A) site was altered by the presence of an upstream intron suggests differences in the way nuclear factors associate with poly(A) sites in the presence and absence of an upstream intron. Cross-linking of C polypeptide to chimeric RNA increased with RNAs mutated for splicing or polyadenylation consensus sequences and under reaction conditions (high magnesium) that inhibited polyadenylation. Furthermore, cross-linking of hnRNP C polypeptide to precursors containing just the SV40 late poly(A) site was eliminated in the presence of competing poly(U); polyadenylation, however, was unaffected. Correlation of loss of activity with high levels of hnRNP C polypeptide cross-linking raises questions about the specificity of the interaction between the hnRNP C polypeptide and polyadenylation precursor RNAs in vitro

Study of UV surface plasmons on metallic nanostructures and its applications to nanophotonics

Science.gov (United States)

Zhou, Liangcheng

Modern nanotechnology requires the characterization ability in the order of 100 nm or smaller. This resolution requirement cannot be met by using conventional optical microscopy. Nowadays, the mainstream technique that is universally adopted to characterize optical properties on this length scale is Near-field Scanning Optical Microscopy (NSOM). In the effort to improve the resolution and efficiency of NSOM techniques, both nanoscopic fabrication and imaging techniques are critical because the light field strongly intereacts with the metallic NSOM probe or other surfaces to form surface plasmons (SPs). However, much is still unknown about the behavior of light interacting with metallic nanostructures. This calls for research that develops the tool set, methodology and that includes both experimental characterization, and numerical simulations, for the investigation of SPs. The short wavelength of UV light makes it particularly desirable for many industrial processes. So far, little research has been carried out to understand surface plasmon in the UV spectral region. Like conventional optics, UV SPs have unique properties and optical behavior. For this purpose, we modified our existing NSOM into a Photon Scanning Tunneling Microscope (PTSM) and demonstrate its power for the imaging of UV SPs. We present what we believe to be the first direct mapping of the UV SPs on an Al2O3/Al surface. UV SP modes launched by one-dimensional slits or two-dimensional groove arrays and corresponding interference phenomenon were both observed. We then use the same methodology in the engineering of optimized nano aperture such as UV bowtie nanoantenna. For the latter, we find a strong UV intensity profile which is localized to less than 50nm caused by a localized surface plasmon resonance. The relationship of optical field enhancement and antenna geometric shape is studied using numerical simulations and NSOM experiments. In another project, we examine the propagation of light from

Aerosols and surface UV products form Ozone Monitoring Instrument observations: An overview

NARCIS (Netherlands)

Torres, O.; Tanskanen, A.; Veihelmann, B.; Ahn, C.; Braak, R.; Bhartia, P.K.; Veefkind, J.P.; Levelt, P.F.

2007-01-01

We present an overview of the theoretical and algorithmic aspects of the Ozone Monitoring Instrument (OMI) aerosol and surface UV algorithms. Aerosol properties are derived from two independent algorithms. The nearUV algorithm makes use of OMI observations in the 350-390 nm spectral region to

Wettability modification of human tooth surface by water and UV and electron-beam radiation

International Nuclear Information System (INIS)

Tiznado-Orozco, Gaby E.; Reyes-Gasga, José; Elefterie, Florina; Beyens, Christophe; Maschke, Ulrich; Brès, Etienne F.

2015-01-01

The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed. Wettability measurements of the samples were done in dry and wet conditions and after ultraviolet (UV) and electron beam (EB) irradiations. The results indicate that water by itself was able to increase the hydrophobicity of these materials. The UV irradiation momentarily reduced the contact angle values, but they recovered after a short time. EB irradiation raised the contact angle and maintained it for a long time. Both enamel and dentin surfaces showed a wide range of contact angles, from approximately 10° (hydrophilic) to 90° (hydrophobic), although the contact angle showed more variability on enamel than on dentin surfaces. Whether the sample's surface had been polished or etched did not influence the contact angle value in wet conditions. - Highlights: • Human tooth surface wettability changes in dry/wet and UV/EB radiation conditions. • More variability in contact angle is observed on enamel than on dentin surfaces. • Water by itself increases the hydrophobicity of the human tooth surface. • UV irradiation reduces momentarily the human tooth surface hydrophobicity. • EB irradiation increases and maintains the hydrophobicity for a long time

Wettability modification of human tooth surface by water and UV and electron-beam radiation

Energy Technology Data Exchange (ETDEWEB)

Tiznado-Orozco, Gaby E., E-mail: gab0409@gmail.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Unidad Académica de Odontología, Universidad Autónoma de Nayarit, Edificio E7, Ciudad de la Cultura “Amado Nervo”, C.P. 63190 Tepic, Nayarit (Mexico); Reyes-Gasga, José, E-mail: jreyes@fisica.unam.mx [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Instituto de Física, UNAM, Circuito de la Investigación s/n, Ciudad Universitaria, 04510 Coyoacan, México, D.F. (Mexico); Elefterie, Florina, E-mail: elefterie_florina@yahoo.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Beyens, Christophe, E-mail: christophe.beyens@ed.univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Maschke, Ulrich, E-mail: Ulrich.Maschke@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Brès, Etienne F., E-mail: etienne.bres@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France)

2015-12-01

The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed. Wettability measurements of the samples were done in dry and wet conditions and after ultraviolet (UV) and electron beam (EB) irradiations. The results indicate that water by itself was able to increase the hydrophobicity of these materials. The UV irradiation momentarily reduced the contact angle values, but they recovered after a short time. EB irradiation raised the contact angle and maintained it for a long time. Both enamel and dentin surfaces showed a wide range of contact angles, from approximately 10° (hydrophilic) to 90° (hydrophobic), although the contact angle showed more variability on enamel than on dentin surfaces. Whether the sample's surface had been polished or etched did not influence the contact angle value in wet conditions. - Highlights: • Human tooth surface wettability changes in dry/wet and UV/EB radiation conditions. • More variability in contact angle is observed on enamel than on dentin surfaces. • Water by itself increases the hydrophobicity of the human tooth surface. • UV irradiation reduces momentarily the human tooth surface hydrophobicity. • EB irradiation increases and maintains the hydrophobicity for a long time.

Electrochemical analysis of the UV treated bactericidal Ti6Al4V surfaces

Energy Technology Data Exchange (ETDEWEB)

Pacha-Olivenza, Miguel A. [Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Gallardo-Moreno, Amparo M., E-mail: amparogm@unex.es [Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Vadillo-Rodríguez, Virginia; González-Martín, M. Luisa [Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Pérez-Giraldo, Ciro [Department of Microbiology, Faculty of Medicine, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Galván, Juan C. [National Centre for Metallurgical Research (CENIM-CSIC), Av. Gregorio del Amo 8, 28040-Madrid (Spain)

2013-04-01

This research investigates in detail the bactericidal effect exhibited by the surface of the biomaterial Ti6Al4V after being subjected to UV-C light. It has been recently hypothesized that small surface currents, occurring as a consequence of the electron–hole pair recombination taking place after the excitation process, are behind the bactericidal properties displayed by this UV-treated material. To corroborate this hypothesis we have used different electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization plots and Mott–Schottky plots. EIS and Mott–Schottky plots have shown that UV-C treatment causes an initial increase on the surface electrical conduction of this material. In addition, EIS and polarization plots demonstrated that higher corrosion currents occur at the UV treated than at the non-irradiated samples. Despite this increase in the corrosion currents, EIS has also shown that such currents are not likely to affect the good stability of this material oxide film since the irradiated samples completely recovered the control values after being stored in dark conditions for a period not longer than 24 h. These results agree with the already-published in vitro transitory behavior of the bactericidal effect, which was shown to be present at initial times after the biomaterial implantation, a crucial moment to avoid a large number of biomaterial associated infections. Highlights: ► Bactericidal response of UV-treated Ti6Al4V is explained through electrochemistry. ► There is an increase in the superficial electrical conduction after UV-treatment. ► Higher corrosion currents for UV-treated against non-UV-treated samples are shown. ► EIS shows the recuperation on irradiated samples in agreement with microbial tests.

Electrochemical analysis of the UV treated bactericidal Ti6Al4V surfaces

International Nuclear Information System (INIS)

Pacha-Olivenza, Miguel A.; Gallardo-Moreno, Amparo M.; Vadillo-Rodríguez, Virginia; González-Martín, M. Luisa; Pérez-Giraldo, Ciro; Galván, Juan C.

2013-01-01

This research investigates in detail the bactericidal effect exhibited by the surface of the biomaterial Ti6Al4V after being subjected to UV-C light. It has been recently hypothesized that small surface currents, occurring as a consequence of the electron–hole pair recombination taking place after the excitation process, are behind the bactericidal properties displayed by this UV-treated material. To corroborate this hypothesis we have used different electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization plots and Mott–Schottky plots. EIS and Mott–Schottky plots have shown that UV-C treatment causes an initial increase on the surface electrical conduction of this material. In addition, EIS and polarization plots demonstrated that higher corrosion currents occur at the UV treated than at the non-irradiated samples. Despite this increase in the corrosion currents, EIS has also shown that such currents are not likely to affect the good stability of this material oxide film since the irradiated samples completely recovered the control values after being stored in dark conditions for a period not longer than 24 h. These results agree with the already-published in vitro transitory behavior of the bactericidal effect, which was shown to be present at initial times after the biomaterial implantation, a crucial moment to avoid a large number of biomaterial associated infections. Highlights: ► Bactericidal response of UV-treated Ti6Al4V is explained through electrochemistry. ► There is an increase in the superficial electrical conduction after UV-treatment. ► Higher corrosion currents for UV-treated against non-UV-treated samples are shown. ► EIS shows the recuperation on irradiated samples in agreement with microbial tests

Icy Saturnian satellites: Disk-integrated UV-IR characteristics and links to exogenic processes

Science.gov (United States)

Hendrix, Amanda R.; Filacchione, Gianrico; Paranicas, Chris; Schenk, Paul; Scipioni, Francesca

2018-01-01

Combined Cassini observations obtained at similar observing geometries in the ultraviolet through infrared spectral range, along with additional ultraviolet (UV) data from Hubble Space Telescope where available, are used to study system-wide trends in spectral albedos of the inner icy Saturnian satellites (Mimas, Enceladus, Tethys, Dione, Rhea). We derive UV and visible geometric albedos and UV absorption strengths of the leading and trailing hemispheres and compare with E ring grain flux and charged particle intensities (electrons and ions of varying energies) to those hemispheres. We find that the UV absorption strength on the leading and trailing hemispheres is anti-correlated with E ring grain flux. On the trailing hemispheres, the UV absorption strength is correlated with intensity of electrons in the tens of keV range. We suggest that these relationships could imply links with the organic component of the E ring. Radiolytic processing of organics causes the products to become spectrally redder, increasing the UV absorption strength. Such processing occurs while organic-rich grains are in the E ring, and increases with exposure time in the E ring, such that grains interacting with Rhea are redder (more processed) than those impacting moons closer to Enceladus. Further processing (and associated darkening/reddening) occurs on the trailing hemispheres of the satellites, via radiolysis by electrons in the tens of keV range. Silicates and salts also redden with weathering; however because organics are present in the E ring in significantly greater abundance than salts or silicates, we suggest here that weathering of organics dominates the coloring of the inner Saturnian moons.

UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

Energy Technology Data Exchange (ETDEWEB)

Rugheimer, S.; Sasselov, D. [Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge (United States); Segura, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México (Mexico); Kaltenegger, L., E-mail: srugheimer@cfa.harvard.edu [Carl Sagan Institute, Cornell University, Ithaca, NY 14853 (United States)

2015-06-10

The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

International Nuclear Information System (INIS)

Rugheimer, S.; Sasselov, D.; Segura, A.; Kaltenegger, L.

2015-01-01

The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments

Biobased Nanoparticles for Broadband UV Protection with Photostabilized UV Filters

NARCIS (Netherlands)

Hayden, D.R.|info:eu-repo/dai/nl/412640694; Imhof, A.|info:eu-repo/dai/nl/145641600; Velikov, K. P.|info:eu-repo/dai/nl/239483472

2016-01-01

Sunscreens rely on multiple compounds to provide effective and safe protection against UV radiation. UV filters in sunscreens, in particular, provide broadband UV protection but are heavily linked to adverse health effects due to the generation of carcinogenic skin-damaging reactive oxygen species

Morphology of IR and UV Laser-induced Structural Changes on Silicon Surfaces

International Nuclear Information System (INIS)

Jimenez-Jarquin, J.; Haro-Poniatowski, E.; Fernandez-Guasti, M.; Hernandez-Pozos, J.L.

2005-01-01

Using scanning electronic microscopy, we analyze the structural changes induced in silicon (100) wafers by focused IR (1064 nm) and UV (355 nm) nanosecond laser pulses. The experiments were performed in the laser ablation regime. When a silicon surface is irradiated by laser pulses in an O2 atmosphere conical microstructures are obtained. The changes in silicon surface morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however the final result consist of an array of microcones when the experiment is carried out in oxygen. We employ a random scanning technique to irradiate silicon surfaces over large areas. In this form we have obtained large patterned areas

Surface reflectance of Antarctic bryophytes and protection from UV and visible light

International Nuclear Information System (INIS)

Robinson, S.A.; Wasley, J.; Turnbull, J.

2000-01-01

Full text: As well as determining the amount of solar radiation available for photosynthesis, the surface reflectance and absorptance characteristics of plants are their first defence against damaging effects of solar radiation. The solar spectrum can be damaging to plants in many ways. At shorter wavelengths, UV-B (280-320 nm) radiation can cause lesions in nucleic acid and proteins. Excess levels of visible radiation (400-750) can cause photoinhibition whilst high absorbtance of longer wavelengths (>750) leads to increases in temperature that can be detrimental in some environments. The adaptation of surface reflectance properties of vascular plants to particular environments are well known in some ecosystems. For example in desert ecosystems pubescent leaf surfaces that increase reflectance are common and have been demonstrated to be important to protection from photoinhibition. The epidermal characteristics of some plants are also known to change in absorptance, due to the accumulation of specific compounds. For example flavonoids which are effective screens against UV-B radiation, increase upon exposure to UV-B radiation. In this study we surveyed the natural variability in surface reflectance in mosses growing in continental Antarctica. Antarctica is experiencing large increases in incident UV-B radiation due to reductions in concentrations of stratospheric ozone. Additionally over the summer months (November January), when moss is exposed to direct sunlight, levels of visible solar radiation are also high, increasing the likelihood of photoinhibitory damage in moss. Our aim in this study is to describe the natural variability in the surface reflectance characteristics of moss, such that we have a baseline with which to assess future changes in response to changes in global climate, and imposed experimental treatments, and also to develop hypotheses with respect to how mosses have adapted to the cold and arid antarctic environment. Variability in surface

Investigation of static and dynamic wetting transitions of UV responsive tunable wetting surfaces

International Nuclear Information System (INIS)

Pant, Reeta; Singha, Subhash; Bandyopadhyay, Aritra; Khare, Krishnacharya

2014-01-01

Ultraviolet (UV) radiation responsive surfaces, with tunable wetting properties, are fabricated by spin casting polystyrene/titania nanocomposite dispersion in tetrahydrofuran on silicon substrates. The prepared samples are found hydrophilic due to the presence of the water miscible solvent. Upon annealing, as the solvent evaporates, samples become superhydrophobic due to presence of hydrophobic polystyrene and formation of nano and micro scale surface roughness due to titania nanoparticles. Effect of different annealing temperatures and time on resulting wettability is investigated. Photocatalytic property of titania is exploited to make transition from superhydrophobic to hydrophilic state upon UV exposure. Subsequently, upon annealing again at elevated temperatures for sufficient time, the UV exposed hydrophilic samples recover their superhydrophobicity showing transition from hydrophilic to superhydrophobic state. Detailed static and dynamic study of these reversible transitions, between superhydrophobic and hydrophilic states, due to UV exposure and annealing is presented in this article.

A comparison study of Riboflavin/UV-A and Rose-Bengal/Green light cross-linking of the rabbit corneas using optical coherence elastography

Science.gov (United States)

Li, Jiasong; Singh, Manmohan; Han, Zhaolong; Vantipalli, Srilatha; Liu, Chih-Hao; Wu, Chen; Raghunathan, Raksha; Kazemi, Tina; Twa, Michael D.; Larin, Kirill V.

2016-03-01

The biomechanical properties of the cornea are critical factors which determine its health and subsequent visual acuity. Keratoconus is a structural degeneration of the cornea which can diminish vision quality. Riboflavin/UV-A corneal collagen cross-linking (UV-CXL) is an emerging treatment that increases the stiffness of the cornea and improves its ability to resist further degeneration. While UV-CXL has shown great promise for effective therapy of the keratoconus, there are concerns associated with the UV irradiation, such as keratocyte cytotoxicity. Rose-bengal/green light corneal collagen cross-linking (RGX) has been proposed as an alternative to UV-CXL. Because of the high absorbance of the rose-bengal dye at green wavelengths, the treatment time is significantly shorter than with UV-CXL. Moreover, because green light is used in lieu of UV irradiation, there are no cytotoxic side-effects. In this study, noncontact optical coherence elastography (OCE) was used to compare the outcomes of UV-CXL and RGX treatment in rabbit cornea. Low-amplitude (micrometer scale) elastic waves were induced by a focused air-pulse loading system. The elastic wave propagation was then imaged by a phase-stabilized swept source OCE (PhS-SSOCE) system. The changes in the viscoelasticity of the corneas were quantified by a previously developed modified Rayleigh Lamb frequency model. The depth-resolved micro-scale phase-velocity distribution in the cornea was used to reveal the depth-wise heterogeneity before and after both cross-linking techniques. Our results show that UV-CXL and RGX increased the stiffness of the corneas by ~54% and ~5% while reducing the viscosity by ~42% and ~17%, respectively. The depth-wise phase velocities showed that UV-CXL affected the anterior ~1/3 of the corneas, while RGX only affected the anterior ~1/7 of the corneas.

Reconstruction of solar spectral surface UV irradiances using radiative transfer simulations.

Science.gov (United States)

Lindfors, Anders; Heikkilä, Anu; Kaurola, Jussi; Koskela, Tapani; Lakkala, Kaisa

2009-01-01

UV radiation exerts several effects concerning life on Earth, and spectral information on the prevailing UV radiation conditions is needed in order to study each of these effects. In this paper, we present a method for reconstruction of solar spectral UV irradiances at the Earth's surface. The method, which is a further development of an earlier published method for reconstruction of erythemally weighted UV, relies on radiative transfer simulations, and takes as input (1) the effective cloud optical depth as inferred from pyranometer measurements of global radiation (300-3000 nm); (2) the total ozone column; (3) the surface albedo as estimated from measurements of snow depth; (4) the total water vapor column; and (5) the altitude of the location. Reconstructed daily cumulative spectral irradiances at Jokioinen and Sodankylä in Finland are, in general, in good agreement with measurements. The mean percentage difference, for instance, is mostly within +/-8%, and the root mean square of the percentage difference is around 10% or below for wavelengths over 310 nm and daily minimum solar zenith angles (SZA) less than 70 degrees . In this study, we used pseudospherical radiative transfer simulations, which were shown to improve the performance of our method under large SZA (low Sun).

TiO2 micro-nano-hybrid surface to alleviate biological aging of UV-photofunctionalized titanium

Directory of Open Access Journals (Sweden)

Iwasa F

2011-06-01

Full Text Available Fuminori Iwasa1, Naoki Tsukimura1, Yoshihiko Sugita1, Rajita Kodali Kanuru1, Katsutoshi Kubo1, Hafiz Hasnain1, Wael Att1,2, Takahiro Ogawa11Laboratory of Bone and Implant Sciences (LBIS, The Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Prosthodontics, Dental School, Albert-Ludwigs University, Freiburg, GermanyAbstract: Bioactivity and osteoconductivity of titanium degrade over time after surface processing. This time-dependent degradation is substantial and defined as the biological aging of titanium. UV treatment has shown to reactivate the aged surfaces, a process known as photofunctionalization. This study determined whether there is a difference in the behavior of biological aging for titanium with micro-nano-hybrid topography and titanium with microtopography alone, following functionalization. Titanium disks were acid etched to create micropits on the surface. Micro-nano-hybrid surfaces were created by depositioning 300-nm diameter TiO2 nodules onto the micropits using a previously established self-assembly protocol. These disks were stored for 8 weeks in the dark to allow sufficient aging, then treated with UV light for 48 hours. Rat bone marrow–derived osteoblasts were cultured on fresh disks (immediately after UV treatment, 3-day-old disks (disks stored for 3 days after UV treatment, and 7-day-old disks. The rates of cell attachment, spread, proliferation, and levels of alkaline phosphatase activity, and calcium deposition were reduced by 30%–50% on micropit surfaces, depending on the age of the titanium. In contrast, 7-day-old hybrid surfaces maintained equivalent levels of bioactivity compared with the fresh surfaces. Both micropit and micro-nano-hybrid surfaces were superhydrophilic immediately after UV treatment. However, after 7 days, the micro-nano-hybrid surfaces became hydrorepellent

Thermal and UV Hydrosilylation of Alcohol-Based Bifunctional Alkynes on Si (111) surfaces: How surface radicals influence surface bond formation.

Science.gov (United States)

Khung, Y L; Ngalim, S H; Scaccabarozi, A; Narducci, D

2015-06-12

Using two different hydrosilylation methods, low temperature thermal and UV initiation, silicon (111) hydrogenated surfaces were functionalized in presence of an OH-terminated alkyne, a CF3-terminated alkyne and a mixed equimolar ratio of the two alkynes. XPS studies revealed that in the absence of premeditated surface radical through low temperature hydrosilylation, the surface grafting proceeded to form a Si-O-C linkage via nucleophilic reaction through the OH group of the alkyne. This led to a small increase in surface roughness as well as an increase in hydrophobicity and this effect was attributed to the surficial etching of silicon to form nanosize pores (~1-3 nm) by residual water/oxygen as a result of changes to surface polarity from the grafting. Furthermore in the radical-free thermal environment, a mix in equimolar of these two short alkynes can achieve a high contact angle of ~102°, comparable to long alkyl chains grafting reported in literature although surface roughness was relatively mild (rms = ~1 nm). On the other hand, UV initiation on silicon totally reversed the chemical linkages to predominantly Si-C without further compromising the surface roughness, highlighting the importance of surface radicals determining the reactivity of the silicon surface to the selected alkynes.

Crosslink the Novel Group of Polymeric Binders BioCo by the UV-radiation

Directory of Open Access Journals (Sweden)

Grabowska B.

2016-06-01

Full Text Available The spectroscopic FT-IR and FT-Raman methods allowed to identify the cross-linking process of the aqueous composition of poly(acrylic acid/sodium salt of carboxymethyl starch (PAA/CMS-Na applied as a binder for moulding sands (as a novel group binders BioCo. The cross-linking was performed by physical agent, applying the UV-radiation. The results of structural studies (IR, Raman confirm the overlapping of the process of cross-linking polymer composition PAA/CMS-Na in UV radiation. Taking into account the ingredients and structure of the polymeric composition can also refer to a curing process in a binder - mineral matrix mixture. In the system of binder-mineral matrix under the influence of ultraviolet radiation is also observed effect of binding. However, the bonding process does not occur in the entire volume of the investigated system, but only on the surface, which gives some possibilities for application in the use of UV curing surface of cores, and also to cure sand moulds in 3D printing technology.

An oxygen-insensitive degradable resist for fabricating metallic patterns on highly curved surfaces by UV-nanoimprint lithography.

Science.gov (United States)

Hu, Xin; Huang, Shisong; Gu, Ronghua; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

2014-10-01

In this paper, an oxygen-insensitive degradable resist for UV-nanoimprint is designed, com-prising a polycyclic degradable acrylate monomer, 2,10-diacryloyloxymethyl-1,4,9,12-tetraoxa-spiro [4.2.4.2] tetradecane (DAMTT), and a multifunctional thiol monomer pentaerythritol tetra(3-mercaptopropionate) (PETMP). The resist can be quickly UV-cured in the air atmosphere and achieve a high monomer conversion of over 98%, which greatly reduce the adhesion force between the resist and the soft mold. High conversion, in company with an adequate Young's modulus (about 1 GPa) and an extremely low shrinkage (1.34%), promises high nanoimprint resolution of sub-50 nm. The cross-linked resist is able to break into linear molecules in a hot acid solvent. As a result, metallic patterns are fabricated on highly curved surfaces via the lift off process without the assistance of a thermoplastic polymer layer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The influence of surface topography of UV coated and printed cardboard on the print gloss

Directory of Open Access Journals (Sweden)

Igor Karlović

2010-09-01

Full Text Available The incident light on the printed surface undergoes through several processes of scattering, absorbtion and reflectiondepending on the surface topography and structure of the material. The specular part of the surface reflection is commonlyattributed as the geometric component of the reflection, and when measured is associated with specular gloss.The diffuse part of the surface reflection contains the chromatic part of the reflection and is commonly calculatedthrough colorimetric values. Using UV coatings as surface enhacement materials which affect the optical propertiesof coated surfaces and final appearance of the printed product forms new surface topography over the existingone. We have investigated the influence of three different amounts of UV glossy and matte oveprint coating on themeasured specular gloss of printed cardboard samples. The different amount of coatings on the printed samples wereachived using three different screen stencils of 180 threads/cm, 150 threads/cm and 120 threads/cm thread count.The cardboard samples were analysed with AFM and SEM microscopes to obtain surface topography and roughnessvalues which were evaluated with the measured geometric values speficied as instrumental gloss. The surfaceswith a specific amount of UV coatings showed a new formed topography which influences the reflection of light.The changes in topography were evaluated through surface roughness parameters which showed a decline of surfaceroughness with tht additional ammount of glossy and matte coatings. The obtained and calculated correlations showthere is a high correlation between coating ammount and surface roughness change and gloss for the glossy UVcoating. The results for the matte UV coatings showed lower correlation for the gloss and surface roughness.

Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

OpenAIRE

Hess, M.; Koepke, P.

2008-01-01

A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy...

Optical properties of thin films of zinc oxide quantum dots and polydimethylsiloxane: UV-blocking and the effect of cross-linking.

Science.gov (United States)

Eita, Mohamed; El Sayed, Ramy; Muhammed, Mamoun

2012-12-01

Thin films of polydimethylsiloxane (PDMS) and ZnO quantum dots (QDs) were built up as multilayers by spin-coating. The films are characterized by a UV-blocking ability that increases with increasing number of bilayers. Photoluminescence (PL) emission spectra of the thin films occur at 522 nm, which is the PL wavelength of the ZnO QDs dispersion, but with a lower intensity and a quantum yield (QY) less than 1% that of the dispersion. Cross-linking has introduced new features to the absorption spectra in that the absorption peak was absent. These changes were attributed to the morphological and structural changes revealed by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR), respectively. TEM showed that the ZnO particle size in the film increased from 7 (±2.7) nm to 16 (±7.8) upon cross-linking. The FTIR spectra suggest that ZnO QDs are involved in the cross-linking of PDMS and that the surface of the ZnO QDs has been chemically modified. Copyright © 2012 Elsevier Inc. All rights reserved.

A UV-Induced Genetic Network Links the RSC Complex to Nucleotide Excision Repair and Shows Dose-Dependent Rewiring

Directory of Open Access Journals (Sweden)

Rohith Srivas

2013-12-01

Full Text Available Efficient repair of UV-induced DNA damage requires the precise coordination of nucleotide excision repair (NER with numerous other biological processes. To map this crosstalk, we generated a differential genetic interaction map centered on quantitative growth measurements of >45,000 double mutants before and after different doses of UV radiation. Integration of genetic data with physical interaction networks identified a global map of 89 UV-induced functional interactions among 62 protein complexes, including a number of links between the RSC complex and several NER factors. We show that RSC is recruited to both silenced and transcribed loci following UV damage where it facilitates efficient repair by promoting nucleosome remodeling. Finally, a comparison of the response to high versus low levels of UV shows that the degree of genetic rewiring correlates with dose of UV and reveals a network of dose-specific interactions. This study makes available a large resource of UV-induced interactions, and it illustrates a methodology for identifying dose-dependent interactions based on quantitative shifts in genetic networks.

Surface modification of silica nanoparticles by UV-induced graft polymerization of methyl methacrylate.

Science.gov (United States)

Kim, Sooyeon; Kim, Eunhye; Kim, Sungsoo; Kim, Woosik

2005-12-01

In this study we modified the surface of silica nanoparticles with methyl methacrylate by UV-induced graft polymerization. It is a surface-initiated polymerization reaction induced by ultraviolet irradiation. The resulting organic-inorganic nanocomposites were near-monodisperse and fabricated without homopolymerization of the monomer. Substantial increase in mean particle size was observed by SEM image analysis after UV-induced grafting of methyl methacrylate onto pure silica particles. FT-Raman spectroscopy and X-ray photoelectron spectroscopy studies of these materials revealed the successful grafting of methyl methacrylate onto the silica surface. The formation of a covalent bond between the grafted PMMA chains and silica surface was indicated by FT-Raman spectra. Thermogravimetric analysis of the PMMA-grafted silica particles indicated the polymer contents in good agreement with SEM photographs.

Pollution patterns and underlying relationships of benzophenone-type UV-filters in wastewater treatment plants and their receiving surface water.

Science.gov (United States)

Wu, Ming-Hong; Li, Jian; Xu, Gang; Ma, Luo-Dan; Li, Jia-Jun; Li, Jin-Song; Tang, Liang

2018-05-15

The environmental behaviors of emerging pollutants, benzophenone-type UV filters (BP-UV filters) and their derivatives were investigated in four wastewater treatment plants (WWTPs), and their receiving surface waters in Shanghai. The concentration level of selected BP-UV filters in the WWTPs was detected from ngL -1 to μgL -1 . BP (621-951ngL -1 ) and BP-3 (841-1.32 × 10 3 ngL -1 ) were the most abundant and highest detection frequency individuals among the target BP-UV filters in influents, whereas BP (198-400ngL -1 ), BP-4 (93.3-288ngL -1 ) and BP-3 (146-258ngL -1 ) were predominant in effluents. BP-UV filters cannot be completely removed and the total removal efficiency varied widely (-456% to 100%) during the treatment process. It can be inferred that the usage of BP and BP-3 are higher than other BP-UV filters in the study area. The lowest and highest levels were BP-2 (ND-7.66ngL -1 ) and BP-3 (68.5-5.01 × 10 3 ng L -1 ) in the receiving surface water, respectively. Interestingly, the seasonal variation of BP-3 is larger than those of other BP-UV filters in surface water from Shanghai. There is no obvious pollution pattern of BP-UV filters in the surface water from the cosmetic factory area. The correlation analysis of BP-UV filters between WWTPs effluents and nearby downstream water samples suggested that BP-UV filters emitted from some WWTPs might be the main source of receiving surface water. Preliminary risk assessment indicated that the levels of BP-UV filters detected by the effluent posed medium to high risk to fish as well as other aquatic organisms. Copyright © 2018 Elsevier Inc. All rights reserved.

Atmospheric Constraints on the Surface UV Environment of Mars at 3.9 Ga Relevant to Prebiotic Chemistry

Science.gov (United States)

Ranjan, Sukrit; Wordsworth, Robin; Sasselov, Dimitar D.

2017-08-01

Recent findings suggest that Mars may have been a clement environment for the emergence of life and may even have compared favorably to Earth in this regard. These findings have revived interest in the hypothesis that prebiotically important molecules or even nascent life may have formed on Mars and been transferred to Earth. UV light plays a key role in prebiotic chemistry. Characterizing the early martian surface UV environment is key to understanding how Mars compares to Earth as a venue for prebiotic chemistry. Here, we present two-stream, multilayer calculations of the UV surface radiance on Mars at 3.9 Ga to constrain the surface UV environment as a function of atmospheric state. We explore a wide range of atmospheric pressures, temperatures, and compositions that correspond to the diversity of martian atmospheric states consistent with available constraints. We include the effects of clouds and dust. We calculate dose rates to quantify the effect of different atmospheric states on UV-sensitive prebiotic chemistry. We find that, for normative clear-sky CO2-H2O atmospheres, the UV environment on young Mars is comparable to young Earth. This similarity is robust to moderate cloud cover; thick clouds (τcloud ≥ 100) are required to significantly affect the martian UV environment, because cloud absorption is degenerate with atmospheric CO2. On the other hand, absorption from SO2, H2S, and dust is nondegenerate with CO2, meaning that, if these constituents build up to significant levels, surface UV fluence can be suppressed. These absorbers have spectrally variable absorption, meaning that their presence affects prebiotic pathways in different ways. In particular, high SO2 environments may admit UV fluence that favors pathways conducive to abiogenesis over pathways unfavorable to it. However, better measurements of the spectral quantum yields of these pathways are required to evaluate this hypothesis definitively.

UV Light Induced Surface Modification of HDPE Films with Bioactive Compounds

Czech Academy of Sciences Publication Activity Database

Daniloska, V.; Blazevska-Gilev, J.; Dimova, V.; Fajgar, Radek; Tomovska, R.

2010-01-01

Roč. 256, č. 7 (2010), s. 2276-2283 ISSN 0169-4332 Institutional research plan: CEZ:AV0Z40720504 Keywords : surface modification * uv irradiation * benzocaine Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.795, year: 2010

Ultraviolet (UV)-reflective paint with ultraviolet germicidal irradiation (UVGI) improves decontamination of nosocomial bacteria on hospital room surfaces.

Science.gov (United States)

Jelden, Katelyn C; Gibbs, Shawn G; Smith, Philip W; Hewlett, Angela L; Iwen, Peter C; Schmid, Kendra K; Lowe, John J

2017-06-01

An ultraviolet germicidal irradiation (UVGI) generator (the TORCH, ClorDiSys Solutions, Inc.) was used to compare the disinfection of surface coupons (plastic from a bedrail, stainless steel, and chrome-plated light switch cover) in a hospital room with walls coated with ultraviolet (UV)-reflective paint (Lumacept) or standard paint. Each surface coupon was inoculated with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus faecalis (VRE), placed at 6 different sites within a hospital room coated with UV-reflective paint or standard paint, and treated by 10 min UVC exposure (UVC dose of 0-688 mJ/cm 2 between sites with standard paint and 0-553 mJ/cm 2 with UV-reflective paint) in 8 total trials. Aggregated MRSA concentrations on plastic bedrail surface coupons were reduced on average by 3.0 log 10 (1.8 log 10 Geometric Standard Deviation [GSD]) with standard paint and 4.3 log 10 (1.3 log 10 GSD) with UV-reflective paint (p = 0.0005) with no significant reduction differences between paints on stainless steel and chrome. Average VRE concentrations were reduced by ≥4.9 log 10 (surface types with UV-reflective paint and ≤4.1 log 10 (hospital bed from the UVGI generator, MRSA concentrations on average were reduced by 1.3 log 10 (1.7 log 10 GSD) with standard paint and 4.7 log 10 (1.3 log 10 GSD) with UV-reflective paint (p hospital room walls with UV-reflective paint enhanced UVGI disinfection of nosocomial bacteria on various surfaces compared to standard paint, particularly at a surface placement site indirectly exposed to UVC light.

Researchers lack data on trends in UV radiation at Earth's surface

International Nuclear Information System (INIS)

Zurer, P.S.

1993-01-01

Current anxiety about depletion of stratospheric ozone stems from the expected resulting increase in biologically damaging ultraviolet (UV) radiation at Earth's surface. Atmospheric ozone absorbs sunlight with wavelengths shorter than 320 nm--the highest-energy UV-B wavelengths (280-320 nm) that can damage DNA in living systems. But surprisingly, despite firm evidence the ozone layer is being eroded by chlorine and bromine from man-made compounds, very little information exists on how UV light intensity is changing. Solid data from Antarctica reveal that UV radiation soars under the ozone hole, where fully half of the atmospheric ozone is destroyed each spring. But elsewhere on the globe, where ozone has been thinning at a rate of a few percent per decade, the corresponding trends in UV intensity are not at all clear. In the late 1970s and early 1980s the problem of ozone depletion seemed solved. The US had banned the use of chlorofluorocarbons (CFCs) in aerosols. Model calculations were predicting CFCs would cause only a small loss of ozone by the second half of the 21st century. Costly monitoring of UV radiation commanded little attention. Attitudes began to change with the 1985 discovery of the Antarctic ozone hole. The National Science Foundation (NSF) established UV monitoring stations in the Antarctic in 1988, adding an Alaskan station in 1990. Both the Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) have programs in the works that will eventually place monitoring stations across the US, but it will be many years before researchers have access to the kind of extensive database necessary to reliably evaluation long-term trends in UV intensity

Anthropogenic changes in the surface all-sky UV-B radiation through 1850-2005 simulated by an Earth system model

Science.gov (United States)

Watanabe, S.; Takemura, T.; Sudo, K.; Yokohata, T.; Kawase, H.

2012-06-01

The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280-315 nm) radiation through 1850-2005 is evaluated using an Earth system model. Responses of UV-B dose to anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N-60° N and 120° E-150° E), where the effect of aerosols (ca. 70%) dominates the total UV-B change.

UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi.

Science.gov (United States)

Lando, Gabriela Albara; Marconatto, Letícia; Kessler, Felipe; Lopes, William; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

2017-07-18

Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU) are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae , when the films were pre-treated with Ultraviolet (UV) irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), scanning electron microscopy (SEM), and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

Directory of Open Access Journals (Sweden)

Gabriela Albara Lando

2017-07-01

Full Text Available Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR, scanning electron microscopy (SEM, and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

Chemical imaging and solid state analysis at compact surfaces using UV imaging

DEFF Research Database (Denmark)

Wu, Jian X.; Rehder, Sönke; van den Berg, Frans

2014-01-01

and excipients in a non-invasive way, as well as mapping the glibenclamide solid state form. An exploratory data analysis supported the critical evaluation of the mapping results and the selection of model parameters for the chemical mapping. The present study demonstrated that the multi-wavelength UV imaging......Fast non-destructive multi-wavelength UV imaging together with multivariate image analysis was utilized to visualize distribution of chemical components and their solid state form at compact surfaces. Amorphous and crystalline solid forms of the antidiabetic compound glibenclamide...

Formation of quasi-periodic nano- and microstructures on silicon surface under IR and UV femtosecond laser pulses

International Nuclear Information System (INIS)

Ionin, Andrei A; Golosov, E V; Kolobov, Yu R; Kudryashov, Sergei I; Ligachev, A E; Makarov, Sergei V; Novoselov, Yurii N; Seleznev, L V; Sinitsyn, D V

2011-01-01

Quasi-periodic nano- and microstructures have been formed on silicon surface using IR ( λ ≈ 744 nm) and UV ( λ ≈ 248 nm) femtosecond laser pulses. The influence of the incident energy density and the number of pulses on the structured surface topology has been investigated. The silicon nanostructurisation thresholds have been determined for the above-mentioned wavelengths. Modulation of the surface relief at the doubled spatial frequency is revealed and explained qualitatively. The periods of the nanostructures formed on the silicon surface under IR and UV femtosecond laser pulses are comparatively analysed and discussed.

Planar UV excilamp excited by a surface barrier discharge

Energy Technology Data Exchange (ETDEWEB)

Guivan, N N [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine); Janca, J [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Brablec, A [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Stahel, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); SlavIcek, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Shimon, L L [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine)

2005-09-07

In this paper, the typical characteristics of a planar excilamp based on KrCl* and XeCl* exciplex molecules are presented. The excitation of the working mixture Kr/Xe/Cl{sub 2} is realized by means of the surface barrier discharge at pressures of 0.1-1 bar. The following properties are measured and discussed: spectra emitted by the plasma in the UV/VIS/NIR spectral range, intensity of emitted light versus total pressure in the discharge, the composition of the working mixture and the power of emitted light. The radiation power versus input electric power, and space distribution of the emitted light including basic electrical parameters of the discharge were also measured. It was shown that the characteristic power of UV radiation emitted in the spectral range 200-400 nm is about 6 mW cm{sup -2} while the efficiency could be about 8%.

Development and Testing of the New Surface LER Climatology for OMI UV Aerosol Retrievals

Science.gov (United States)

Gupta, Pawan; Torres, Omar; Jethva, Hiren; Ahn, Changwoo

2014-01-01

Ozone Monitoring Instrument (OMI) onboard Aura satellite retrieved aerosols properties using UV part of solar spectrum. The OMI near UV aerosol algorithm (OMAERUV) is a global inversion scheme which retrieves aerosol properties both over ocean and land. The current version of the algorithm makes use of TOMS derived Lambertian Equivalent Reflectance (LER) climatology. A new monthly climatology of surface LER at 354 and 388 nm have been developed. This will replace TOMS LER (380 nm and 354nm) climatology in OMI near UV aerosol retrieval algorithm. The main objectives of this study is to produce high resolution (quarter degree) surface LER sets as compared to existing one degree TOMS surface LERs, to product instrument and wavelength consistent surface climatology. Nine years of OMI observations have been used to derive monthly climatology of surface LER. MODIS derived aerosol optical depth (AOD) have been used to make aerosol corrections on OMI wavelengths. MODIS derived BRDF adjusted reflectance product has been also used to capture seasonal changes in the surface characteristics. Finally spatial and temporal averaging techniques have been used to fill the gaps around the globes, especially in the regions with consistent cloud cover such as Amazon. After implementation of new surface data in the research version of algorithm, comparisons of AOD and single scattering albedo (SSA) have been performed over global AERONET sites for year 2007. Preliminary results shows improvements in AOD retrievals globally but more significance improvement were observed over desert and bright locations. We will present methodology of deriving surface data sets and will discuss the observed changes in retrieved aerosol properties with respect to reference AERONET measurements.

Effect of enhanced UV-B radiation of adaxial leaf surface micromorphology and epicuticular wax biosynthesis of sugar maple

International Nuclear Information System (INIS)

Gordon, D.C.; Percy, K.E.; Riding, R.T.

1998-01-01

Sugar maple (Acer saccharum [Marsh.]) seedlings were exposed to UV-B BE ranging from 0.61 kJ m -2 d -1 to 12.48 kJ m -2 d -1 . Increasing UV-B intensity was associated with changes in micromorphological characteristics of the adaxial leaf surface. In vivo incorporation of [1- 14 C] acetate into sugar maple adaxial leaf surface epicuticular wax indicated (p<0.05) a UV-B sensitivity threshold at or near 6.2 kJ m -2 d -1 . Exposure to dosages greater than 6.2 kJ m -2 d -1 resulted in a significant (p<0.05) decrease in wax biosynthesis. The proportion of [1- 14 C] acetate incorporated into each of the different epicuticular wax classes changed with increasing UV-B. Incorporation of [1- 14 C] acetate into alkyl esters decreased while incorporation into alkanes increased with increasing UV-B dose. The effects of enhanced UV-B dose recorded in this experiment may have implications for cuticle function. (author)

A Facile in Situ and UV Printing Process for Bioinspired Self-Cleaning Surfaces

Directory of Open Access Journals (Sweden)

Marina A. González Lazo

2016-08-01

Full Text Available A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA within a low-shrinkage acrylated hyperbranched polymer (HBP and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the polymer-air interface within 30 min, leading to a ten-fold increase of fluorine concentration at the surface compared with the initial bulk concentration and a water contact angle (WCA of 108°. A 200 ms flash of UV light was used to chemically crosslink the PFUA at the HBP surface prior to UV printing with a polydimethylsiloxane (PDMS negative template of red and yellow rose petals and lotus leaves. This flash immobilization hindered the reverse migration of PFUA within the bulk HBP upon contacting the PDMS template, and enabled to produce texturized surfaces with WCA well above 108°. The synthetic red rose petal was hydrophobic (WCA of 125° and exhibited the adhesive petal effect. It was not superhydrophobic due to insufficient concentration of fluorine at its surface, a result of the very large increase of the surface of the printed texture. The synthetic yellow rose petal was quasi-superhydrophobic (WCA of 143°, roll-off angle of 10° and its self-cleaning ability was not good also due to lack of fluorine. The synthetic lotus leaf did not accurately replicate the intricate nanotubular crystal structures of the plant. In spite of this, the fluorine concentration at the surface was high enough and the leaf was superhydrophobic (WCA of 151°, roll-off angle below 5° and also featured self-cleaning properties.

IR and UV laser-induced morphological changes in silicon surface under oxygen atmosphere

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Jarquin, J.; Fernandez-Guasti, M.; Haro-Poniatowski, E.; Hernandez-Pozos, J.L. [Laboratorio de Optica Cuantica, Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, C.P. 09340, Mexico D.F. (Mexico)

2005-08-01

We irradiated silicon (100) wafers with IR (1064 nm) and UV (355 nm) nanosecond laser pulses with energy densities within the ablation regime and used scanning electron microscopy to analyze the morphological changes induced on the Si surface. The changes in the wafer morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however if the experiment is carried out in O{sub 2} the final result is an array of microcones. We also employed a random scanning technique to irradiate the silicon wafer over large areas, in this case the microstructure patterns consist of a ''semi-ordered'' array of micron-sized cones. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Surface modification of poly(tetrafluoroethylene) films by low energy Ar+ ion-beam activation and UV-induced graft copolymerization

International Nuclear Information System (INIS)

Zhang Yan; Huan, A.C.H.; Tan, K.L.; Kang, E.T.

2000-01-01

Surface modification of poly(tetrafluoroethylene) (PTFE) films by Ar + ion-beam irradiation with varying ion energy and ion dose was carried out. The changes in surface composition of the irradiated PTFE films were characterized, both in situ and after exposure to air, by X-ray photoelectron spectroscopy (XPS). The possible mechanisms of chemical reaction induced by the incident ion beam on the surface of PTFE film included defluorination, chain scission and cross-linking, as indicated by the presence of the characteristic peak components associated with the - - -CF 3 , - - -CF, and C(CF 2 ) 4 species in the C 1s core-level spectra, the decrease in surface [F]/[C] ratio, and the increase in surface micro-hardness of the Ar + ion-beam-treated PTFE films. Furthermore, the free radicals generated by the ion-beam could react with oxygen in the air to give rise to oxidized carbon species, such as the peroxides, on the PTFE surface. Thus, after exposure to air, the Ar + ion-beam-pretreated PTFE films were susceptible to further surface modification by UV-induced graft copolymerization with a vinyl monomer, such as acrylamide (AAm). The graft concentrations were deduced from the XPS-derived surface stoichiometries. The Ar + ion energy and the ion dose affected not only the surface composition of the treated films but also the graft copolymerization efficiency of the corresponding pretreated films

Surface coatings of unsaturated polyester resin Kamper wood (Dry obalan ops spp.) by using UV radiation

International Nuclear Information System (INIS)

Sugiarto Danu; Yusuf Sudo Hadi; Novi Eka Putri

1999-01-01

Kamper wood (Dryobalanops spp.) has high contribution in wood working industry and most of them need surface coating process. Radiation curing of surface coating, especially the use of ultra-violet (UV) light have potential to give contribution in the wood finishing. The experiment on surface coating of kamper wood has been conducted by using UV-radiation. Unsaturated polyester resin with the commercial name of Yucalac type 157 was used as coating materials after being added with styrene monomer, some fillers and radical photoinitiator of 2-hydroxy-2-2-methyl-l- phenyl propanone. Four photoinitiator concentration levels of 1.5 ; 2 ; 2.5 and 3 % by weight of resin were used. The coating materials were coated onto the wood panel samples by using high pressure sprayer. The wood samples were then exposed to irradiation by using 80 Watts/cm UV-source with variable conveyor speed of 3 ; 4 ; 5 and 5.8 m/min. Formulation of coating materials, pendulum hardness, adhesion, and gloss of cured films were evaluated

Leaf surface wax is a source of plant methane formation under UV radiation and in the presence of oxygen

DEFF Research Database (Denmark)

Bruhn, Dan; Mikkelsen, Teis Nørgaard; Rolsted, M. M. M.

2014-01-01

to this, we demonstrated that the UV radiation-induced CH4 emission is independent of leaf area index above unity. Further, we observed that the presence of O2 in the atmosphere was necessary for achieving the highest rates of CH4 emission. Methane formation from leaf surface wax is supposedly a two...... investigated the potential of the leaf surface wax itself as a source of UV radiationinduced leaf aerobic CH4 formation. Isolated leaf surface wax emitted CH4 at substantial rates in response to UV radiation. This discovery has implications for how the phenomenon should be scaled to global levels. In relation...

Colour Changes on the Surface of the Rock Materials Due to UV-A and UV-B Rays

Science.gov (United States)

Binal, Adil; Ayderman, Aykut; Sel, Aylin

2015-04-01

The colour of the rocks used in the current buildings, and historical monuments is an important parameter in architecture and engineering. In addition, engineering geologists use the colour in order to identify the weathering class of rock material. The main colour of the stone, especially, are affected by the mineral size, the colour of the primary minerals and matrix material, as well as the colour of the accessory minerals. Due to atmospheric effects, changes in the outer surface colour of the rocks used as siding materials occur with over time. Factors causing the colour change are carbon dioxide (CO2), ozone (O3), sulphate (SO2, SO3) and nitrate (NOx) from the atmosphere with aerosols as well as UV rays from the sun. There is no more work in the literature on colour changes caused by UV-A and UV-B rays. In this study, the effects of ultraviolet in the colour of the surfaces of basalt, limestone, ignimbrite, travertine and sandstone have been simulated with a new experimental device in the laboratory medium. Lutron colour analyser (RGB-1002) was used for the measurements of RGB colours. Colour differences between the beginning and end of tests were determined with the standard practice for calculation of colour tolerances and colour differences from instrumentally measured colour coordinates (ASTM D2244). As a result of the experiments performed, lighten that seem on dark-grey micritic limestone (colour change ratio, CCR: 17.06) and basalt samples (CCR: 8.24) become even visually noticeable. Black and red ignimbrite samples having high porosity were presented the lower rate of colour changes. Finally, colour darkening has been observed in the light-coloured travertine (CCR: 13.8) and sandstone samples (CCR: 20.99).

A case study of the impact of boundary layer aerosol size distribution on the surface UV irradiance

Energy Technology Data Exchange (ETDEWEB)

Kikas, U.; Reinhart, A. [University of Tartu (Estonia). Institute of Environmental Physics; Vaht, M. [Parnu Institute of Health Resort Treatment and Medical Rehabilitation (Estonia); Veismann, U. [Tartu Observatory (Estonia)

2001-07-01

The relationship between scattering characteristics of surface aerosol and surface UV irradiance was examined on the basis of the measurements carried out in June-August 1999 in Parnu, Estonia on the Eastern coast of the Baltic Sea (58{sup o}22'27 ''N, 24{sup o}30'43 ''E) The UV radiation spectra (300-34Onm) were measured with the Ocean Optics Inc. UV spectrometer PC 1000, the aerosol size distributions (3-1000nm) were measured with the electric aerosol spectrometer EAS. A case study was conducted for six sequential cloudless days, when the decrease of the surface UV irradiance was seemingly influenced by atmospheric aerosol. Aerosol radiative properties were calculated from the measured size distributions that represented the maritime polar (North Atlantic) and mixed maritime-continental air. The aerosol optical depths at 500nm for the North Atlantic air were estimated to be from 0.08 to 0. 13. The spectral aerosol optical depth agreed well with the Angstrom law, the Angstrom exponent ({alpha} varied from day to day between values of 0.52-0.90. Aerosol asymmetry factor at 300nm changed between values of 0.76 and 0.80, and was highly correlated with the mean radius of aerosol number distribution. The total aerosol UV scattering was mostly influenced by changes in aerosol with a diameter of 100-560nm. The aerosol scattering coefficients were positively correlated with the relative humidity of air. The ground aerosol properties were used for calculating the surface UV irradiance from the radiative transfer model of Bird and Riordan (J. Climate Appl. Meteorol. 25 (1986)). The calculated UV irradiances correlated quite well with the measured ones, showing that the use of ground aerosol data for radiative transfer calculations turned out reasonable results. However, ignoring the changes in the aerosol vertical distribution resulted in overestimation of aerosol optical depth on hazy days. (author)

Damage caused by a nanosecond UV laser on a heated copper surface

Energy Technology Data Exchange (ETDEWEB)

Henč-Bartolić, V., E-mail: visnja.henc@fer.hr [University of Zagreb, Faculty of Electrical Engineering and Computing, Unska 3, 10000 Zagreb (Croatia); Bončina, T. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia); Jakovljević, S., E-mail: suzana.jakovljevic@fsb.hr [University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Ivana Lučića 5, 10002 Zagreb (Croatia); Panjan, P. [Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Zupanič, F. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia)

2016-08-15

Highlights: • A Cu-plate was exposed to nanosecond UV laser with max. energy 1.1 J/cm{sup 2}. • Surface topography was studied on the cold and heated copper plate. • At room temperature, a crater formed, the melt was ejected from it. • Capillary waves formed in the vicinity of the crater at 360 °C. - Abstract: This work studied the effect of thin copper plate temperature on its surface morphology after irradiation using a pulsed nanosecond UV laser. The surface characteristics were investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam and stylus profilometry. When a target was at room temperature, a crater and the radial flow of molten Cu from the crater was observed. When the thin target was warm (about 360 °C ± 20 °C), a crater was smaller, and quasi-semicircular waves with the periodicity of around 3 μm appeared in its vicinity. The origin of the waves is Marangoni effect, causing thermocapillary waves, which in same occasions had a structure of final states of chaos in Rayleigh–Bénard convection.

Surface Coating of Musa Brachycarpa Trunk Using UV-Radiation

International Nuclear Information System (INIS)

Danu, Sugiarto; Sumarni, Anik; Nurhadi, Agus; Puspita, Rita

2000-01-01

An experiment on UV-curing of surface coating of Musa brachycarpa was carried out using urethane acrylate polymer films. Radiation curable material was the mixture of urethane acrylate resin, tripropylene glycol diacrylate monomer (TPGDA) and radical photo initiator of 2,2-dimethyl -2-hydroxy acetophenone. The TPGDA concentrations in the mixture with urethane acrylate resin were 60; 70 and 80% weight, Whereas concentrations of photo initiator were varied at the level 1.5:2.0 and 2.5% by weight based on resin and monomer mixture. Irradiation was conducted by using 80 Watt/cm intensity UV-light at the conveyor speed of 2: 3 and 4 m/min. Analysis and film properties observed were IR spectrum, gel fraction, hardness, abrasion resistance, glossy and chemical, solvent and stain resistances. Films have good resistances against 1% sodium carbonate, 5% acetic acid, 50% alcohol, thinner and red, blue and black permanent marker, except against 10% sodium hydroxide and 10% sulfuric acid. Optimum condition was achieved at the photo initiator concentration level of 2% and conveyor speed of 3 m/min

Superhydrophilic poly (styrene co acrylonitrile)-ZnO nanocomposite surfaces for UV shielding and self-cleaning applications

Science.gov (United States)

Singh, Rajender; Sharma, Ramesh; Barman, P. B.; Sharma, Dheeraj

2017-11-01

UV shielding based super hydrophilic material is developed in the present formulation by in situ emulsion polymerization of poly (styrene-acrylonitrile) with ZnO nanoparticles. The ESI-MS technique confirms the structure of polymer nanocomposite by their mass fragments. The XRD study confirms the presence of ZnO phase in polymer matrix. PSAN/ZnO nanocomposite leads to give effective UV shielding (upto 375 nm) and visible luminescence with ZnO content in polymer matrix. The FESEM and TEM studies confirm the symmetrical, controlled growth of PNs. The incorporation of ZnO nanofillers into PSAN matrix lead to restructuring the PNs surfaces into superhydrophilic surfaces in water contact angle (WCA) from 70° to 10°. We believe our synthesized PSAN/ZnO nanocomposite could be potential as UV shielding, luminescent and super hydrophilic nature based materials in related commercial applications.

MEASUREMENT OF SURFACE SOLAR UV-B RADIATION AT TROPICAL COASTAL STATION BAKKHALI IN WEST BENGAL, INDIA

OpenAIRE

R. BHATTACHARYA; A. BHOUMICK

2012-01-01

Surface solar ultraviolet irradiance has been measured at Bakkhali (21.8ºN, 87.8ºE), a tropical rural station on the coast of Bay of Bengal, India in West Bengal. The measurements show a remarkable variation in UV-B load exists with a peak value at noon. The blockage of direct UV radiation in mangrove forest of costal site appears low when compared with UV load beneath the multiple trees of Mangifera indica in an inland site of Kalyani (22058' N, 88028' E), West Bengal. Mangrove forests have ...

Mass spectrometric analysis of a UV-cross-linked protein-DNA complex: tryptophans 54 and 88 of E. coli SSB cross-link to DNA

DEFF Research Database (Denmark)

Steen, Hanno; Petersen, Jørgen; Mann, Matthias

2001-01-01

acid and peptide entities present in such heteroconjugates. Sample preparation of the peptide-nucleic acid heteroconjugates is, therefore, a crucial step in any mass spectrometry-based analytical procedure. This study demonstrates the performance of four different MS-based strategies to characterize E....... coli single-stranded DNA binding protein (SSB) that was UV-cross-linked to a 5-iodouracil containing DNA oligomer. Two methods were optimized to circumvent the need for standard liquid chromatography and gel electrophoresis, thereby dramatically increasing the overall sensitivity of the analysis...

Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

Energy Technology Data Exchange (ETDEWEB)

Razavizadeh, Mahmoud; Jamshidi, Masoud, E-mail: mjamshidi@iust.ac.ir

2016-08-30

Highlights: • In this research UV-irradiated PET fabric was chemically modified. • The fabric at first carboxylated under UV irradiation using glutaric anhydride, then it was grafted using isocyanate (i.e. MDI). • The surface of the fabric was characterized before and after each treating satge. • The composite samples were prepared and tested for T-Peel test. The surfaces of the fabrics were surface characterized to understand. - Abstract: Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

International Nuclear Information System (INIS)

Razavizadeh, Mahmoud; Jamshidi, Masoud

2016-01-01

Highlights: • In this research UV-irradiated PET fabric was chemically modified. • The fabric at first carboxylated under UV irradiation using glutaric anhydride, then it was grafted using isocyanate (i.e. MDI). • The surface of the fabric was characterized before and after each treating satge. • The composite samples were prepared and tested for T-Peel test. The surfaces of the fabrics were surface characterized to understand. - Abstract: Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

Identification of novel direct protein-protein interactions by irradiating living cells with femtosecond UV laser pulses.

Science.gov (United States)

Itri, Francesco; Monti, Daria Maria; Chino, Marco; Vinciguerra, Roberto; Altucci, Carlo; Lombardi, Angela; Piccoli, Renata; Birolo, Leila; Arciello, Angela

2017-10-07

The identification of protein-protein interaction networks in living cells is becoming increasingly fundamental to elucidate main biological processes and to understand disease molecular bases on a system-wide level. We recently described a method (LUCK, Laser UV Cross-linKing) to cross-link interacting protein surfaces in living cells by UV laser irradiation. By using this innovative methodology, that does not require any protein modification or cell engineering, here we demonstrate that, upon UV laser irradiation of HeLa cells, a direct interaction between GAPDH and alpha-enolase was "frozen" by a cross-linking event. We validated the occurrence of this direct interaction by co-immunoprecipitation and Immuno-FRET analyses. This represents a proof of principle of the LUCK capability to reveal direct protein interactions in their physiological environment. Copyright © 2017 Elsevier Inc. All rights reserved.

Biodosimetric analysis of medium pressure UV disinfection reactor treating unfiltered surface water

International Nuclear Information System (INIS)

Leinan, B.E.; Craik, S.A.; Smith, D.W.; Belosevic, M.

2002-01-01

Many small and medium-sized communities use chlorination of surface water as their sole treatment of potable water. Ultraviolet (UV) disinfection may offer these communities a cost effective treatment option for protection against pathogens not readily inactivated by chlorine. The effectiveness of UV reactors for microorganism reduction, however, is sensitive to UV dose delivery, which is in turn influenced by water quality characteristics. The effectiveness of a Calgon Carbon Inc. Sentinel medium-pressure UV reactor for microorganism reduction was determined using biodosimetry with two non-pathogenic indicator organisms - MS2 phage and Bacillus subtilis. Testing was conducted using low turbidity (<0.5 NTU) lake water characterized by relatively high absorbance in the UV range (UVT of approx. 87 to 88% at 254 nm). The efficiency of UV dose delivery in the reactor was determined for various operating conditions by calculating the normalized reductive equivalent irradiance (REI). With a single lamp in operation, the normalized REI measured with B. subtilis increased significantly when the flow rate through the reactor was increased from 380 L/min to 1140 L/min. This increase in reactor efficiency was believed to be due to improved reactor hydrodynamics and axial mixing that accompanied the higher flow rates. In contrast, treatment efficiency based on biodosimetry with MS2 phage was found to decrease with increasing flow rate when a single lamp was in operation. In general, treatment efficiency was greater when more than one adjacent lamp was in operation, suggesting that the influence of flow short-circuiting with single lamp operation. Differences between the outcomes observed with the two indicator microorganisms were not resolved, however, it was concluded that reactor efficiency was sensitive to both water flow rate and the number of adjacent lamps that were in operation. (author)

Influence of cloud fraction and snow cover to the variation of surface UV radiation at King Sejong station, Antarctica

Science.gov (United States)

Lee, Yun Gon; Koo, Ja-Ho; Kim, Jhoon

2015-10-01

This study investigated how cloud fraction and snow cover affect the variation of surface ultraviolet (UV) radiation by using surface Erythemal UV (EUV) and Near UV (NUV) observed at the King Sejong Station, Antarctica. First the Radiative Amplification Factor (RAF), the relative change of surface EUV according to the total-column ozone amount, is compared for different cloud fractions and solar zenith angles (SZAs). Generally, all cloudy conditions show that the increase of RAF as SZA becomes larger, showing the larger effects of vertical columnar ozone. For given SZA cases, the EUV transmission through mean cloud layer gradually decreases as cloud fraction increases, but sometimes the maximum of surface EUV appears under partly cloudy conditions. The high surface EUV transmittance under broken cloud conditions seems due to the re-radiation of scattered EUV by cloud particles. NUV transmission through mean cloud layer also decreases as cloud amount increases but the sensitivity to the cloud fraction is larger than EUV. Both EUV and NUV radiations at the surface are also enhanced by the snow cover, and their enhancement becomes higher as SZA increases implying the diurnal variation of surface albedo. This effect of snow cover seems large under the overcast sky because of the stronger interaction between snow surface and cloudy sky.

Surface functionalisation of polypyrrole films using UV light induced radical activation

International Nuclear Information System (INIS)

Lisboa, P.; Gilliland, D.; Ceccone, G.; Valsesia, A.; Rossi, F.

2006-01-01

Electrochemically deposited polypyrrole (PPy) films were functionalised with amine or carboxylic function. The functionalisation was done by grafting allylamine or acrylic acid (AAc) using UV light radical activation. The active groups of the surface were quantified by X-ray photoelectron spectroscopy (XPS) after chemical derivatisation with trifluoroethanol (TFE) or 4-trifluoromethylbenzaldehyde (TFBA), respectively. Grafting with AAc completely covered the PPy film introducing high levels of carboxylic function. In the case of allylamine grafting, a saturation point at low amine carbon level was achieved. Further characterisation of the surfaces was done by time of flight secondary ion mass spectroscopy (TOF-SIMS), atomic force microscope (AFM) and scanning electron microscope (SEM)

The optimal UV exposure time for vitamin D3 synthesis and erythema estimated by UV observations in Korea

Science.gov (United States)

Lee, Y. G.; Koo, J. H.

2016-12-01

Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) from spectral UV measurements during 2006-2010. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied to the broadband UV measured by UV-Biometer at 6 sites in Korea Thus, the optimal UV exposure time for vitamin D3 synthesis and erythema was estimated for diurnal, seasonal, and annual scales over Korea. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice

Effect of surface plasmon resonance on the photocatalytic activity of Au/TiO2 under UV/visible illumination.

Science.gov (United States)

Tseng, Yao-Hsuan; Chang, I-Guo; Tai, Yian; Wu, Kung-Wei

2012-01-01

In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

UV-blocking spectacle lens protects against UV-induced decline of visual performance.

Science.gov (United States)

Liou, Jyh-Cheng; Teng, Mei-Ching; Tsai, Yun-Shan; Lin, En-Chieh; Chen, Bo-Yie

2015-01-01

Excessive exposure to sunlight may be a risk factor for ocular diseases and reduced visual performance. This study was designed to examine the ability of an ultraviolet (UV)-blocking spectacle lens to prevent visual acuity decline and ocular surface disorders in a mouse model of UVB-induced photokeratitis. Mice were divided into 4 groups (10 mice per group): (1) a blank control group (no exposure to UV radiation), (2) a UVB/no lens group (mice exposed to UVB rays, but without lens protection), (3) a UVB/UV400 group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [UV400 coating]), and (4) a UVB/photochromic group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [photochromic coating]). We investigated UVB-induced changes in visual acuity and in corneal smoothness, opacity, and lissamine green staining. We also evaluated the correlation between visual acuity decline and changes to the corneal surface parameters. Tissue sections were prepared and stained immunohistochemically to evaluate the structural integrity of the cornea and conjunctiva. In blank controls, the cornea remained undamaged, whereas in UVB-exposed mice, the corneal surface was disrupted; this disruption significantly correlated with a concomitant decline in visual acuity. Both the UVB/UV400 and UVB/photochromic groups had sharper visual acuity and a healthier corneal surface than the UVB/no lens group. Eyes in both protected groups also showed better corneal and conjunctival structural integrity than unprotected eyes. Furthermore, there were fewer apoptotic cells and less polymorphonuclear leukocyte infiltration in corneas protected by the spectacle lenses. The model established herein reliably determines the protective effect of UV-blocking ophthalmic biomaterials, because the in vivo protection against UV-induced ocular damage and visual acuity decline was easily defined.

Covalent bindings in proteins following UV-C irradiation

International Nuclear Information System (INIS)

Diezel, W.; Meffert, H.; Soennichsen, N.; Reinicke, C.

1980-01-01

Following a UV-C irradiation of catalase cross-linked catalase subunits could be detected by sodium dodecylsulfate gel electrophoresis. The subunits of aldolase were not cross-linked. The origin of covalent bindings in the catalase molecule is suggested to be effected by a free radical chain reaction induced by the heme component of catalase after UV-C irradiation. (author)

Prediction of UV spectra and UV-radiation damage in actual plasma etching processes using on-wafer monitoring technique

International Nuclear Information System (INIS)

Jinnai, Butsurin; Fukuda, Seiichi; Ohtake, Hiroto; Samukawa, Seiji

2010-01-01

UV radiation during plasma processing affects the surface of materials. Nevertheless, the interaction of UV photons with surface is not clearly understood because of the difficulty in monitoring photons during plasma processing. For this purpose, we have previously proposed an on-wafer monitoring technique for UV photons. For this study, using the combination of this on-wafer monitoring technique and a neural network, we established a relationship between the data obtained from the on-wafer monitoring technique and UV spectra. Also, we obtained absolute intensities of UV radiation by calibrating arbitrary units of UV intensity with a 126 nm excimer lamp. As a result, UV spectra and their absolute intensities could be predicted with the on-wafer monitoring. Furthermore, we developed a prediction system with the on-wafer monitoring technique to simulate UV-radiation damage in dielectric films during plasma etching. UV-induced damage in SiOC films was predicted in this study. Our prediction results of damage in SiOC films shows that UV spectra and their absolute intensities are the key cause of damage in SiOC films. In addition, UV-radiation damage in SiOC films strongly depends on the geometry of the etching structure. The on-wafer monitoring technique should be useful in understanding the interaction of UV radiation with surface and in optimizing plasma processing by controlling UV radiation.

Surface characteristics determining the cell compatibility of ionically cross-linked alginate gels

International Nuclear Information System (INIS)

Machida-Sano, Ikuko; Hirakawa, Makoto; Matsumoto, Hiroki; Kamada, Mitsuki; Ogawa, Sakito; Satoh, Nao; Namiki, Hideo

2014-01-01

In this study we investigated differences in the characteristics determining the suitability of five types of ion (Fe 3+ , Al 3+ , Ca 2+ , Ba 2+ and Sr 2+ )-cross-linked alginate films as culture substrates for cells. Human dermal fibroblasts were cultured on each alginate film to examine the cell affinity of the alginates. Since cell behavior on the surface of a material is dependent on the proteins adsorbed to it, we investigated the protein adsorption ability and surface features (wettability, morphology and charge) related to the protein adsorption abilities of alginate films. We observed that ferric, aluminum and barium ion-cross-linked alginate films supported better cell growth and adsorbed higher amounts of serum proteins than other types. Surface wettability analysis demonstrated that ferric and aluminum ion-cross-linked alginates had moderate hydrophilic surfaces, while other types showed highly hydrophilic surfaces. The roughness was exhibited only on barium ion-cross-linked alginate surface. Surface charge measurements revealed that alginate films had negatively charged surfaces, and showed little difference among the five types of gel. These results indicate that the critical factors of ionically cross-linked alginate films determining the protein adsorption ability required for their cell compatibility may be surface wettability and morphology. (paper)

Operational surface UV radiation product from GOME-2 and AVHRR/3 data

OpenAIRE

J. Kujanpää; N. Kalakoski

2015-01-01

The surface ultraviolet (UV) radiation product, version 1.20, generated operationally in the framework of the Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M SAF) of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) is described. The product is based on the total ozone column derived from the measurements of the second Global Ozone Monitoring Experiment (GOME-2) instrument aboard EUMETSA...

Superhydrophobic TiO2-polymer nanocomposite surface with UV-induced reversible wettability and self-cleaning properties.

Science.gov (United States)

Xu, Qian Feng; Liu, Yang; Lin, Fang-Ju; Mondal, Bikash; Lyons, Alan M

2013-09-25

Multifunctional superhydrophobic nanocomposite surfaces based on photocatalytic materials, such as fluorosilane modified TiO2, have generated significant research interest. However, there are two challenges to forming such multifunctional surfaces with stable superhydrophobic properties: the photocatalytic oxidation of the hydrophobic functional groups, which leads to the permanent loss of superhydrophobicity, as well as the photoinduced reversible hydrolysis of the catalytic particle surface. Herein, we report a simple and inexpensive template lamination method to fabricate multifunctional TiO2-high-density polyethylene (HDPE) nanocomposite surfaces exhibiting superhydrophobicity, UV-induced reversible wettability, and self-cleaning properties. The laminated surface possesses a hierarchical roughness spanning the micro- to nanoscale range. This was achieved by using a wire mesh template to emboss the HDPE surface creating an array of polymeric posts while partially embedding untreated TiO2 nanoparticles selectively into the top surface of these features. The surface exhibits excellent superhydrophobic properties immediately after lamination without any chemical surface modification to the TiO2 nanoparticles. Exposure to UV light causes the surface to become hydrophilic. This change in wettability can be reversed by heating the surface to restore superhydrophobicity. The effect of TiO2 nanoparticle surface coverage and chemical composition on the mechanism and magnitude of wettability changes was studied by EDX and XPS. In addition, the ability of the surface to shed impacting water droplets as well as the ability of such droplets to clean away particulate contaminants was demonstrated.

Biodegradation improvement of poly(3-hydroxy-butyrate) films by entomopathogenic fungi and UV-assisted surface functionalization.

Science.gov (United States)

Kessler, Felipe; Marconatto, Leticia; Rodrigues, Roberta da Silva Bussamara; Lando, Gabriela Albara; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

2014-01-05

Ultraviolet (UV)-assisted surface modification in the presence of oxygen was used as initial step to achieve controlled degradation of poly(3-hydroxy-butyrate), PHB, films by entomopathogenic fungi. Treated surfaces were investigated by surface analysis techniques (water contact angle, Fourier Transformed Infrared Spectroscopy in Attenuated Total Reflectance mode, X-ray Photoelectron Spectroscopy, Near-edge X-ray Absorption Fine Structure, Gel Permeation Chromatography, Optical Microscopy, Scanning Electron Microscopy, and weight loss). After the UV-assisted treatments, new carbonyl groups in new chemical environments were detected by XPS and NEXAFS spectroscopy. The oxidizing atmosphere did not allow the formation of CC bonds, indicating that Norrish Type II mechanism is suppressed during or by the treatments. The higher hydrophilicity and concentration of oxygenated functional groups at the surface of the treated films possibly improved the biodegradation of the films. It was observed a clear increase in the growth of this fungus when oxygenated groups were grafted on the polymers surfaces. This simple methodology can be used to improve and control the degradation rate of PHB films in applications that require a controllable degradation rate. Copyright © 2013 Elsevier B.V. All rights reserved.

Impacts of Brown Carbon from Biomass Burning on Surface UV and Ozone Photochemistry in the Amazon Basin

Science.gov (United States)

Mok, Jungbin; Krotkov, Nickolay A.; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F.; Li, Zhangqing; Dickerson, Russell R.;

Impacts of brown carbon from biomass burning on surface UV and ozone photochemistry in the Amazon Basin

KAUST Repository

Mok, Jungbin

2016-11-11

The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or “brown” carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305–368 nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18% and lead to reduced concentrations of radicals OH, HO2, and RO2 by up to 17%, 15%, and 14%, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

Ultraviolet radiation exposure from UV-transilluminators.

Science.gov (United States)

Akbar-Khanzadeh, Farhang; Jahangir-Blourchian, Mahdi

2005-10-01

UV-transilluminators use ultraviolet radiation (UVR) to visualize proteins, DNA, RNA, and their precursors in a gel electrophoresis procedure. This study was initiated to evaluate workers' exposure to UVR during their use of UV-transilluminators. The levels of irradiance of UV-A, UV-B, and UV-C were determined for 29 UV-transilluminators at arbitrary measuring locations of 6, 25, 62, and 125 cm from the center of the UV-transilluminator's filter surface in the direction of the operator's head. The operators (faculty, research staff, and graduate students) worked within 62 cm of the transilluminators, with most subjects commonly working at time ranged from 1 to 60 min. Actinic hazard (effective irradiance level of UVR) was also determined for three representative UV-transilluminators at arbitrary measuring locations of 2.5, 5, 10, 15, 20, 30, 40, and 50 cm from these sets' filter surface in the direction of the operator's head. The allowable exposure time for these instruments was less than 20 sec within 15 cm, less than 35 sec within 25 cm, and less than 2 min within 50 cm from the UV-transilluminators' filter surface. The results of this study suggest that the use of UV-transilluminators exposes operators to levels of UVR in excess of exposure guidelines. It is recommended that special safety training be provided for the affected employees and that exposure should be controlled by one or the combination of automation, substitution, isolation, posted warning signs, shielding, and/or personal protective equipment.

A novel method to prepare superhydrophobic, UV resistance and anti-corrosion steel surface

KAUST Repository

Isimjan, Tayirjan T.

2012-11-01

Both TiO 2 and SiO 2 coated steel surfaces containing micro- and nanoscale binary structures with different surface roughness were successfully fabricated by means of a facile layer by layer deposition process followed by heat treatment. The resulting surfaces were modified by the low free energy chemical PTES (1H,1H,2H,2H-Perfluorodecyltriethoxysilane). The experimental results of wettability exhibit that such modified surfaces have a strong repulsive force to water droplets, their static contact angles exceed 165°, receding angle>160°, advanced angles>170° and slide angle<1°. The resulting surfaces not only exhibit superhydrophobic properties but also show strong UV resistance (after coating SiO 2 on top of TiO 2) and strong stability to various solvents including 0.01% HCl solution. © 2012 Elsevier B.V.

In situ deposition of graphene nanosheets on wood surface by one-pot hydrothermal method for enhanced UV-resistant ability

International Nuclear Information System (INIS)

Wan, Caichao; Jiao, Yue; Li, Jian

2015-01-01

Graphical abstract: - Highlights: • The graphene/wood nanocomposites were fabricated via a mild fast one-pot hydrothermal method. • Graphene nanosheets were in situ deposited on the surface of the wood matrix. • The incorporation of graphene nanosheets results in the improvement in the thermal stability of the graphene/wood. • The graphene/wood exhibits superior UV resistance performance. - Abstract: Graphene nanosheets were successfully in situ deposited on the surface of the wood matrix via a mild fast one-pot hydrothermal method, and the resulting hybrid graphene/wood (GW) were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA). According to the results, the wood matrix was evenly coated by dense uninterrupted multilayer graphene membrane structure, which was formed by layer-by-layer self-assembly of graphene nanosheets. Meanwhile, the graphene coating also induced significant improvement in the thermal stability of GW in comparison with that of the original wood (OW). Accelerated weathering tests were employed to measure and determine the UV-resistant ability of OW and GW. After about six hundred hours of experiments, the surface color change of GW was much less than that of OW; besides, the Fourier transform infrared spectroscopy (FTIR) analysis also proved the less significant changes in surface chemical compositions of GW. The results both indicated that the graphene coating effectively protected wood surface from UV damage. Therefore, this class of GW composite might be expected to be served as high-performance wooden building material for outdoor or some particular harsh environments like strong UV radiation regions use

Investigation of the influence of UV irradiation on collagen thin films by AFM imaging

Energy Technology Data Exchange (ETDEWEB)

Stylianou, Andreas, E-mail: styliand@mail.ntua.gr; Yova, Dido; Alexandratou, Eleni

2014-12-01

Collagen is the major fibrous extracellular matrix protein and due to its unique properties, it has been widely used as biomaterial, scaffold and cell-substrate. The aim of the paper was to use Atomic Force Microscopy (AFM) in order to investigate well-characterized collagen thin films after ultraviolet light (UV) irradiation. The films were also used as in vitro culturing substrates in order to investigate the UV-induced alterations to fibroblasts. A special attention was given in the alteration on collagen D-periodicity. For short irradiation times, spectroscopy (fluorescence/absorption) studies demonstrated that photodegradation took place and AFM imaging showed alterations in surface roughness. Also, it was highlighted that UV-irradiation had different effects when it was applied on collagen solution than on films. Concerning fibroblast culturing, it was shown that fibroblast behavior was affected after UV irradiation of both collagen solution and films. Furthermore, after a long irradiation time, collagen fibrils were deformed revealing that collagen fibrils are consisting of multiple shells and D-periodicity occurred on both outer and inner shells. The clarification of the effects of UV light on collagen and the induced modifications of cell behavior on UV-irradiated collagen-based surfaces will contribute to the better understanding of cell–matrix interactions in the nanoscale and will assist in the appropriate use of UV light for sterilizing and photo-cross-linking applications. - Highlights: • Collagen thin films were formed and exposed in UV irradiation. • Collagen thin films were formed from UV-irradiated collagen solution. • Nanocharacterization of collagen thin films by AFM • Fluorescence and absorption spectroscopy studies on collagen films • Investigation of fibroblast response on collagen films.

Investigation of the influence of UV irradiation on collagen thin films by AFM imaging

International Nuclear Information System (INIS)

Stylianou, Andreas; Yova, Dido; Alexandratou, Eleni

2014-01-01

Collagen is the major fibrous extracellular matrix protein and due to its unique properties, it has been widely used as biomaterial, scaffold and cell-substrate. The aim of the paper was to use Atomic Force Microscopy (AFM) in order to investigate well-characterized collagen thin films after ultraviolet light (UV) irradiation. The films were also used as in vitro culturing substrates in order to investigate the UV-induced alterations to fibroblasts. A special attention was given in the alteration on collagen D-periodicity. For short irradiation times, spectroscopy (fluorescence/absorption) studies demonstrated that photodegradation took place and AFM imaging showed alterations in surface roughness. Also, it was highlighted that UV-irradiation had different effects when it was applied on collagen solution than on films. Concerning fibroblast culturing, it was shown that fibroblast behavior was affected after UV irradiation of both collagen solution and films. Furthermore, after a long irradiation time, collagen fibrils were deformed revealing that collagen fibrils are consisting of multiple shells and D-periodicity occurred on both outer and inner shells. The clarification of the effects of UV light on collagen and the induced modifications of cell behavior on UV-irradiated collagen-based surfaces will contribute to the better understanding of cell–matrix interactions in the nanoscale and will assist in the appropriate use of UV light for sterilizing and photo-cross-linking applications. - Highlights: • Collagen thin films were formed and exposed in UV irradiation. • Collagen thin films were formed from UV-irradiated collagen solution. • Nanocharacterization of collagen thin films by AFM • Fluorescence and absorption spectroscopy studies on collagen films • Investigation of fibroblast response on collagen films

Investigation of γ-(2,3-Epoxypropoxypropyltrimethoxy Silane Surface Modified Layered Double Hydroxides Improving UV Ageing Resistance of Asphalt

Directory of Open Access Journals (Sweden)

Canlin Zhang

2017-01-01

Full Text Available γ-(2,3-Epoxypropoxypropyltrimethoxy silane surface modified layered double hydroxides (KH560-LDHs were prepared and used to improve the ultraviolet ageing resistance of asphalt. The results of X-ray photoelectron spectrometry (XPS indicated that KH560 has been successfully grafted onto the surface of LDHs. The agglomeration of LDHs particles notably reduced after KH560 surface modification according to scanning electron microscopy (SEM, which implied that the KH560 surface modification was helpful to promote the dispersibility of LDHs in asphalt. Then, the influence of KH560-LDHs and LDHs on the physical and rheological properties of asphalt before and after UV ageing was thoroughly investigated. The storage stability test showed that the difference in softening point (ΔS of LDHs modified asphalt decreased from 0.6 °C to 0.2 °C at an LDHs content of 1% after KH560 surface modification, and the tendency became more pronounced with the increase of LDH content, indicating that KH560 surface modification could improve the stability of LDHs in asphalt. After UV ageing, the viscous modulus (G’’ of asphalt significantly reduced, and correspondingly, the elastic modulus (G’ and rutting factor (G*/sin δ rapidly increased. Moreover, the asphaltene increased and the amount of “bee-like” structures of the asphalt decreased. Compared with LDHs, KH560-LDHs obviously restrained performance deterioration of the asphalt, and helped to relieve the variation of the chemical compositions and morphology of asphalt, which suggested that the improvement of KH560-LDHs on UV ageing resistance of asphalt was superior to LDHs.

Physicochemical modifications accompanying UV laser induced surface structures on poly(ethylene terephthalate) and their effect on adhesion of mesenchymal cells.

Science.gov (United States)

Rebollar, Esther; Pérez, Susana; Hernández, Margarita; Domingo, Concepción; Martín, Margarita; Ezquerra, Tiberio A; García-Ruiz, Josefa P; Castillejo, Marta

2014-09-07

This work reports on the formation of different types of structures on the surface of polymer films upon UV laser irradiation. Poly(ethylene terephthalate) was irradiated with nanosecond UV pulses at 193 and 266 nm. The polarization of the laser beam and the irradiation angle of incidence were varied, giving rise to laser induced surface structures with different shapes and periodicities. The irradiated surfaces were topographically characterized by atomic force microscopy and the chemical modifications induced by laser irradiation were inspected via micro-Raman and fluorescence spectroscopies. Contact angle measurements were performed with different liquids, and the results evaluated in terms of surface free energy components. Finally, in order to test the influence of surface properties for a potential application, the modified surfaces were used for mesenchymal stem cell culture assays and the effect of nanostructure and surface chemistry on cell adhesion was evaluated.

Radioactive decontamination through UV laser

International Nuclear Information System (INIS)

Delaporte, Ph.; Gastaud, M.; Sentis, M.; Uteza, O.; Marine, W.; Thouvenot, P.; Alcaraz, J.L.; Le Samedy, J.M.; Blin, D.

2003-01-01

A device allowing the radioactive decontamination of metal surfaces through the use of a pulsed UV laser has been designed and tested. This device is composed of a 1 kW excimer laser linked to a bundle of optic fibers and of a system to recover particles and can operate in active zones. Metal surfaces have the peculiarities to trap radio-elements in a superficial layer of oxide that can be eaten away by laser radiation. Different contaminated metals (stainless steels, INCONEL and aluminium) issued from the nuclear industry have been used for the testing. The most important contaminants were 60 Co, 137 Cs, 154-155 Eu and 125 Sb. The ratio of decontamination was generally of 10 and the volume of secondary wastes generating during the process was very low compared with other decontamination techniques. A decontamination speed of 1 m 2 /h has been reached for aluminium. The state of the surface is an important parameter because radio-elements trapped in micro-cracks are very difficult to remove. (A.C.)

UV Radiation and the Skin

Directory of Open Access Journals (Sweden)

Timothy Scott

2013-06-01

Full Text Available UV radiation (UV is classified as a “complete carcinogen” because it is both a mutagen and a non-specific damaging agent and has properties of both a tumor initiator and a tumor promoter. In environmental abundance, UV is the most important modifiable risk factor for skin cancer and many other environmentally-influenced skin disorders. However, UV also benefits human health by mediating natural synthesis of vitamin D and endorphins in the skin, therefore UV has complex and mixed effects on human health. Nonetheless, excessive exposure to UV carries profound health risks, including atrophy, pigmentary changes, wrinkling and malignancy. UV is epidemiologically and molecularly linked to the three most common types of skin cancer, basal cell carcinoma, squamous cell carcinoma and malignant melanoma, which together affect more than a million Americans annually. Genetic factors also influence risk of UV-mediated skin disease. Polymorphisms of the melanocortin 1 receptor (MC1R gene, in particular, correlate with fairness of skin, UV sensitivity, and enhanced cancer risk. We are interested in developing UV-protective approaches based on a detailed understanding of molecular events that occur after UV exposure, focusing particularly on epidermal melanization and the role of the MC1R in genome maintenance.

Inhibition of charge recombination for enhanced dye-sensitized solar cells and self-powered UV sensors by surface modification

Energy Technology Data Exchange (ETDEWEB)

Chu, Liang, E-mail: chuliang@njupt.edu.cn [Advanced Energy Technology Center, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046 (China); Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology (HUST), Wuhan 430074 (China); Qin, Zhengfei; Liu, Wei [School of Materials Science and Engineering (SMSE), Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046 (China); Ma, Xin’guo, E-mail: maxg2013@sohu.com [Hubei Collaborative Innovation Center for High-efficiency Utilization of Solar Energy, Hubei University of Technology, Wuhan 430068 (China)

2016-12-15

Graphical abstract: Inhibition of charge recombination was utilized to prolong electrode lifetime in dye-sensitized solar cells (DSSCs) and self-powered UV sensors based on TiO{sub 2}-modified SnO{sub 2} photoelectrodes. The electrochemical impedance spectroscopy and open-circuit voltage decay measurements indicated that the electron lifetime was significantly prolonged in DSSCs after TiO{sub 2} modification. And in self-powered UV sensors, the sensitivity and response time were enhanced. - Highlights: • The surface modification to inhibit charge recombination was utilized in photovoltaic devices. • Inhibition of charge recombination can prolong electrode lifetime in photovoltaic devices. • Enhanced DSSCs and self-powered UV sensors based on SnO{sub 2} photoelectrodes were obtained by TiO{sub 2} modification. - Abstract: The surface modification to inhibit charge recombination was utilized in dye-sensitized solar cells (DSSCs) and self-powered ultraviolet (UV) sensors based on SnO{sub 2} hierarchical microspheres by TiO{sub 2} modification. For DSSCs with SnO{sub 2} photoelectrodes modified by TiO{sub 2}, the power conversion efficiency (PCE) was improved from 1.40% to 4.15% under standard AM 1.5G illumination (100 mW/cm{sup 2}). The electrochemical impedance spectroscopy and open-circuit voltage decay measurements indicated that the charge recombination was effectively inhibited, resulting in long electron lifetime. For UV sensors with SnO{sub 2} photoelectrodes modified by TiO{sub 2} layer, the self-powered property was more obvious, and the sensitivity and response time were enhanced from 91 to 6229 and 0.15 s to 0.055 s, respectively. The surface modification can engineer the interface energy to inhibit charge recombination, which is a desirable approach to improve the performance of photoelectric nanodevice.

UV reflectance is associated with environmental conditions in Palaearctic Pieris napi (Lepidoptera: Pieridae).

Science.gov (United States)

Stella, David; Pecháček, Pavel; Meyer-Rochow, Victor Benno; Kleisner, Karel

2018-06-01

The subject of our investigation was the visual features of wing color with special focus on the UV reflectance in the green-veined white butterfly (Pieris napi). Previous studies had concluded that UV reflectance on dorsal wing surfaces is found only in the female P. napi. Based on UV sensitive photography, we analyzed a correlation between 12 geographic and environmental factors and UV reflectance patterns on 3 patches on the forewings of 407 P. napi specimens from the Palaearctic region. Results had shown that females significantly differ from males: they exhibit a 25% higher UV reflectance. To investigate whether and how UV reflectance levels on the forewings and hindwings of both sexes are influenced by the environment, we performed a principal component analysis (PCA) with several environmental variables. For several variables (in particular, latitude and longitude, mean annual temperature and precipitation, and temperature annual range and altitude), the generalized linear model (GLM) model revealed a significant correlation in both sexes. This suggests a link between UV reflectance levels and the environment and distribution of P. napi. We found that stronger UV reflectance is associated with generally more hostile environments and concluded that large-scale environmental factors influence the UV reflectance on the forewings of both male and female green-veined white butterflies. © 2016 Institute of Zoology, Chinese Academy of Sciences.

A near-UV-converted LiMgBO3:Dy3+ nanophosphor: Surface and spectral investigations

International Nuclear Information System (INIS)

Bedyal, A.K.; Kumar, Vinay; Prakash, Ram; Ntwaeaborwa, O.M.; Swart, H.C.

2015-01-01

Graphical abstract: - Highlights: • Combustion method was employed to synthesize LiMgBO 3 :Dy 3+ nanophosphors. • The phosphor can be efficiently excited by near-UV chips. • XPS was done to investigate the chemical constitution and chemical bonding state of elements in the LiMgBO 3 : Dy 3+ nanophosphor. • The calculated CIE coordinates (0.45, 0.46) were found to be in the white spectrum region. - Abstract: A near-ultra violet (UV) converted LiMgBO 3 :Dy 3+ nanophosphors have been synthesized by the combustion method. The structural, spectral and optical properties were examined by powder X-ray diffraction, fluorescent spectrophotometry and UV–vis spectroscopy. The excitation spectra of the phosphors contain sharp peaks at 294, 323, 348 and 385 nm due to the 4f–4f transition of the Dy 3+ ion. The phosphor is efficiently excited by near-UV chips. Upon near-UV excitation the phosphor emits intense blue and yellow with a weak red band centered at 484, 573 and 669 nm respectively, ascribed to the transition of Dy 3+ ion from 4 F 9/2 → 6 H 15/2 , 6 H 13/2 , 6 H 11/2 . The diffuse reflectance spectra of the phosphors were consistent with the excitation spectra and were used to calculate the band gap of the material, approximated to be 5.4 eV. The calculated CIE coordinates (0.45, 0.46) under 348 nm excitation were found to be in the white spectrum region. For surface investigation, X-ray photoelectron spectroscopy was used which confirms the presence of all the elements on the surface of the material

Hybrid 2D patterning using UV laser direct writing and aerosol jet printing of UV curable polydimethylsiloxane

Science.gov (United States)

Obata, Kotaro; Schonewille, Adam; Slobin, Shayna; Hohnholz, Arndt; Unger, Claudia; Koch, Jürgen; Suttmann, Oliver; Overmeyer, Ludger

2017-09-01

The hybrid technique of aerosol jet printing and ultraviolet (UV) laser direct writing was developed for 2D patterning of thin film UV curable polydimethylsiloxane (PDMS). A dual atomizer module in an aerosol jet printing system generated aerosol jet streams from material components of the UV curable PDMS individually and enables the mixing in a controlled ratio. Precise control of the aerosol jet printing achieved the layer thickness of UV curable PDMS as thin as 1.6 μm. This aerosol jet printing system is advantageous because of its ability to print uniform thin-film coatings of UV curable PDMS on planar surfaces as well as free-form surfaces without the use of solvents. In addition, the hybrid 2D patterning using the combination of UV laser direct writing and aerosol jet printing achieved selective photo-initiated polymerization of the UV curable PDMS layer with an X-Y resolution of 17.5 μm.

Femtosecond UV laser non-ablative surface structuring of ZnO crystal: impact on exciton photoluminescence

Energy Technology Data Exchange (ETDEWEB)

Museur, Luc [Laboratoire de Physique des Lasers (LPL), UMR 7538 CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Michel, Jean-Pierre [Laboratoire des Proprietes Mecaniques et Thermodynamiques des Materiaux (LPMTM), UMR 9001 CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Portes, Patrick; Kanaev, Andrei V. [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions (LIMHP), UMR 1311 CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Englezis, Apostolis; Stassinopoulos, Andreas; Anglos, Demetrios [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), 71110 Heraklion, Crete (Greece)

2010-03-15

The ultraviolet (UV) laser irradiation (248 nm) of monocrystalline wurtzite ZnO with 450 fs pulses results in surface modification. A formation of two orthogonal ripple structures with a period of 400-500 nm was observed oriented parallel and perpendicular to the laser beam polarization. The UV exciton emission obtained on the irradiated domains is found greatly enhanced locally up to {approx}10{sup 3} times. The photoluminescence band is redshifted by 2-3 nm and 40% narrower (full width at half-maximum), while at the same time the E{sub 2} (439 cm{sup -1}) Raman band intensity increases up to {approx}50 times. The process is found irreversible with the threshold fluence of 11 mJ/cm{sup 2}, which is considerably lower than the ablation threshold 115 mJ/cm{sup 2}. Fine surface nanostructuring on the scale of {approx}10 nm may be responsible for the observed effect. (c) 2008 Optical Society of America.

Fast simulation tool for ultraviolet radiation at the earth's surface

Science.gov (United States)

Engelsen, Ola; Kylling, Arve

2005-04-01

FastRT is a fast, yet accurate, UV simulation tool that computes downward surface UV doses, UV indices, and irradiances in the spectral range 290 to 400 nm with a resolution as small as 0.05 nm. It computes a full UV spectrum within a few milliseconds on a standard PC, and enables the user to convolve the spectrum with user-defined and built-in spectral response functions including the International Commission on Illumination (CIE) erythemal response function used for UV index calculations. The program accounts for the main radiative input parameters, i.e., instrumental characteristics, solar zenith angle, ozone column, aerosol loading, clouds, surface albedo, and surface altitude. FastRT is based on look-up tables of carefully selected entries of atmospheric transmittances and spherical albedos, and exploits the smoothness of these quantities with respect to atmospheric, surface, geometrical, and spectral parameters. An interactive site, http://nadir.nilu.no/~olaeng/fastrt/fastrt.html, enables the public to run the FastRT program with most input options. This page also contains updated information about FastRT and links to freely downloadable source codes and binaries.

Selective surface functionalization of polystyrene induced by synchrotron or UV radiation in the presence of oxygen or acrylic acid vapors

International Nuclear Information System (INIS)

Kessler, Felipe; Kuhn, Sidiney; Weibel, Daniel E.

2009-01-01

Efficient surface functionalization of Polystyrene (PS) thin films by electromagnetic radiation in combination with a reactive gaseous atmosphere was obtained. Monochromatic synchrotron (SR) or polychromatic UV radiation were used as excitation sources. When SR was used, O 2 was introduced after irradiation into the UHV chamber. UV irradiation was carried out keeping a constant flow of O 2 or acrylic acid (AA) vapors during the photolysis. FTIR-ATR and XPS-NEXAFS spectra were obtained at the UFRGS and the LNLS, Campinas respectively. PS films were functionalized by monochromatic SR and then expose to O 2 at specific transitions such us C 1s →σ * C-C excitation. It was found a high rate of COO, C=O and C-O groups at the surface (> 70%). UV-assisted treatment in the presence of AA vapors showed that an efficient polymerization process took place, such as, it was observed in previous AA low pressure RF plasma treatments. UV-assisted functionalization has the advantage of lower costs and simple set-up compared to plasma treatments. (author)

Co-ordinated ozone and UV project COZUV

International Nuclear Information System (INIS)

Braathen, Geir

1999-01-01

The project encompasses all the major Norwegian research groups in the field of stratospheric ozone and UV research. the duration is from the 1st January 1999 to the 31st December 2000. The tasks carried out will include investigations of the ozone layer over the North Polar and middle latitudes, 3-D chemical modelling, diagnosis of chemical ozone loss, investigations of transport mechanisms between the polar vortex and middle latitudes, study of the coupling between ozone change and climate change in the stratosphere and upper troposphere, scenario calculations in order to investigate the consequences of temperature change in the stratosphere, development of methods to measure global, direct and radiance distribution of UV, to improve UV dose calculations, investigate the influence of clouds on the surface UV radiation and to use existing surface UV radiation measurements together with existing radiation models to investigate the connection between UV radiation and ozone, clouds and surface albedo. The results will be published in various publications, progress reports, by participation in international conferences, through information to the environmental authorities and through information on the Internet

Plant responses to UV-B irradiation are modified by UV-A irradiation

International Nuclear Information System (INIS)

Middleton, E.M.; Teramura, A.H.

1993-01-01

The increasing UV-B radiation (0.28-0.32 μm) reaching the earth's surface is an important concern. Plant response in artificial UV-B irradiation studies has been difficult to assess, especially regarding photosynthetic pigments, because the fluorescent lamps also produce UV-A (0.32-0.40μm) radiation which is involved with blue light in pigment synthesis. Both UV-A and UV-B irradiances were controlled in two glasshouse experiments conducted under relatively high PPFD (> 1300μmol m -2 s -1 ) at two biologically effective daily UV-B irradiances (10.7 and 14.1 kJ m -2 ); UV-A irradiances were matched in Controls (∼5, 9 kJ m -2 ). Normal, chlorophyll-deficient, and flavonoid-deficient isolines of soybean cultivar, Clark, were utilized. Many growth/ pigment variables exhibited a statistically significant interaction between light quality and quantity: in general, UV-A radiation moderated the damaging effects of UV-B radiation. Regression analyses demonstrated that a single negative function related photosynthetic efficiency to carotenoid Content (r 2 =0.73, P≤0.001), implying a open-quotes costclose quotes in maintaining carotenoids for photoprotection. A stomatal limitation to photosynthesis was verified and carotenoid content was correlated with UV-B absorbing compound levels, in UV-B irradiated plants

Mechanical and thermal properties of UV curable polyurethane acrylate composite coatings

International Nuclear Information System (INIS)

Mohd Sofian Alias; Nik Ghazali Nik Salleh; Mohd Hamzah Harun; Mohd Yusof Hamzah; Rosley Che Ismail

2012-01-01

UV curable coating formulation comprises urethane acrylate resin and nano silica as filter were synthesized to develop UV curable inorganic hybrid composite (PUA). The surface of the nano silica was chemically modified to improve its chemical interaction within the urethane acrylate matrix. The modification had been undertaken by applying vinyltrymetoxysilane (VTMOS) that acted as a coupling agent to produce organophilic silica shell (SIMA). The shell is linked to the silica via reaction with the surface silanol group of the silica. The disappearance of methoxy groups in VTMOS was demonstrated by FTIR spectrum. The percentage of silica particles in UV curable hybrid formulation were varied on 5 %, 10 %, 15 %, 20 % and 25 wt % respectively. In this work, the formulation was applied on medium density fiber board (MDF) substrate and subsequent has been irradiated under UV light. Then, the coated MDF were characterized by several testing equipment (TGA, DSC, scratch tester, instron, SEM). From the result, we found that the addition of silica nanoparticles exhibit significant improvement in coating film properties as compared to film without silica nanoparticle includes significant improvement in its modulus and scratch resistance. This make them as promising coating candidate for MDF product. On the other hand, we also found that an increase of silica particle up to 25 wt %, the viscosity has increased rapidly indicates that it is not suitable for acrylate coating formulation due to disappearance of desired effect known as thixotropy. (Author)

Integration of UV-cured Ionogel Electrolyte with Carbon Paper Electrodes

Directory of Open Access Journals (Sweden)

Stephanie Flores Zopf

2014-02-01

Full Text Available A test bed with a coplanar architecture is employed to investigate the integration of an in situ cross-linked, polymer-supported ionogel with several commercially available, high surface area carbon paper electrodes. Specifically, a UV-cured poly(ethylene glycol diacrylate (PEGDA-supported ionogel electrolyte film is formed in situ against a variety of porous electrodes comprising: a carbon fiber paper, a carbon aerogel paper, and four carbon nanotube-based papers. Electrochemical impedance spectroscopy measurements reveal that the relative performance of a particular carbon paper with the neat ionic liquid is not necessarily indicative of its behavior when integrated with the solid ionogel electrolyte. The coplanar test bed can therefore serve as a useful tool to help guide the selection of suitable carbon-based electrode structures for supercapacitors that incorporate UV-cured ionogels created in situ for wearable energy storage applications.

Characterization of solid UV curable 3D printer resins for biological applications

KAUST Repository

Sivashankar, Shilpa

2016-12-19

In this paper, we report a simple method to evaluate biocompatibility of solid UV cross-linked resin as a material for microfluidic devices that can be used for biological applications. We evaluated the biocompatibility of the material in two different ways (1) determining if the UV cured resin inhibits the polymerase chain reaction (PCR) and (2) observing agglutination complex formed on the surface of the UV cured resin when anti-CRP antibodies and C- reactive protein (CRP) proteins were allowed to agglutinate. Six different types of 3D printer resins were compared to test the biocompatibility. The study showed that only few among them could be used for fabrication of micro channels and that had least effect on biological molecules that could be used for PCR and protein interactions. Through these studies it is possible to estimate the curing time of various resin and their type of interaction with biomolecules. This study finds importance in on-chip tissue engineering and organ-on-chip applications.

X-UV lasers and their promising applications

International Nuclear Information System (INIS)

Ros, D.

2004-01-01

The author reviews 30 years of research and achievements concerning X-UV lasers. Typical features of X-UV lasers are: a large number of photons emitted per impulse (between 10 12 and 10 14 ) and very short impulses (between 1 and 100 ps). When a crystal is irradiated by a X-UV laser, these features favor new physical processes that did not appear when the irradiation was performed with other X-UV sources like synchrotron radiation for instance. Their high brilliance and coherence properties make them efficient means as irradiating sources or imaging tools. X-UV laser interferometry allows the mapping of a surface at the nano-metric scale without any interaction between the laser beam and the surface. (A.C.)

Structural origin of surface transformations in arsenic sulfide thin films upon UV-irradiation

International Nuclear Information System (INIS)

Kovalskiy, Andriy; Vlcek, Miroslav; Palka, Karel; Buzek, Jan; York-Winegar, James; Oelgoetz, Justin; Golovchak, Roman; Shpotyuk, Oleh; Jain, Himanshu

2017-01-01

Photostructural transformations within As_xS_1_0_0_-_x (x = 30, 33, 35, 40) thin films upon exposure to LED light of different wavelengths, in both air and argon environments have been studied by high resolution XPS, Raman spectroscopy and LEIS methods. These complementary results show that light of energies close to the band gap does not modify chemical composition of the surface, but induces simple photopolymerization reactions. Superbandgap UV light, however, significantly increases S/As ratio on the surface due to formation of S-rich layer under both environmental conditions. It is proposed that photovaporization of both oxide and non-oxide cage-like molecules is responsible for the observed effect.

Structural origin of surface transformations in arsenic sulfide thin films upon UV-irradiation

Energy Technology Data Exchange (ETDEWEB)

Kovalskiy, Andriy, E-mail: kovalskiya@apsu.edu [Department of Physics & Astronomy, Austin Peay State University, 601 College St., Clarksville, TN 37044 (United States); Vlcek, Miroslav [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, nam. Cs. Legii 565, 530 02 Pardubice (Czech Republic); Palka, Karel [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, nam. Cs. Legii 565, 530 02 Pardubice (Czech Republic); Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 532 10 Pardubice (Czech Republic); Buzek, Jan [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 532 10 Pardubice (Czech Republic); York-Winegar, James; Oelgoetz, Justin; Golovchak, Roman [Department of Physics & Astronomy, Austin Peay State University, 601 College St., Clarksville, TN 37044 (United States); Shpotyuk, Oleh [Vlokh Institute of Physical Optics, 23 Dragomanov str., Lviv 79005 (Ukraine); Institute of Physics of Jan Dlugosz University, 13/15 al. Armii Krajowej, Czestochowa PL-42201 (Poland); Jain, Himanshu [Department of Materials Science & Engineering, Lehigh University, 5 East Packer Ave., Bethlehem, PA 18015 (United States)

2017-02-01

Photostructural transformations within As{sub x}S{sub 100-x} (x = 30, 33, 35, 40) thin films upon exposure to LED light of different wavelengths, in both air and argon environments have been studied by high resolution XPS, Raman spectroscopy and LEIS methods. These complementary results show that light of energies close to the band gap does not modify chemical composition of the surface, but induces simple photopolymerization reactions. Superbandgap UV light, however, significantly increases S/As ratio on the surface due to formation of S-rich layer under both environmental conditions. It is proposed that photovaporization of both oxide and non-oxide cage-like molecules is responsible for the observed effect.

Selective cell culture on UV transparent polymer by F2 laser surface modification

International Nuclear Information System (INIS)

Hanada, Yasutaka; Sugioka, Koji; Kawano, Hiroyuki; Tsuchimoto, Takayoshi; Miyamoto, Iwao; Miyawaki, Atsushi; Midorikawa, Katsumi

2009-01-01

A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F 2 laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F 2 laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

Development of radiation curable surface coating based on soybean oil. part II: Evaluation of the prepared acrylated resin as surface coatings by using EB or UV sources for radiation curing applications

International Nuclear Information System (INIS)

Ibrahim, M.S.; Said, H.M.; Moussa, I.M.

2005-01-01

In recent years, there has been a growing trend in using vegetable oils as raw materials in acylation production that can be cured by UV/EB systems. The acrylated resin formulates by using individually different functional acrylate monomers were prepared and cured by EB or UV sources. The characterization properties of the cured films were investigated in terms of pendulum hardness, bending, impact, gloss, adhesion and chemical tests. Other formulations were prepared by mixing a constant ratio of different functional acrylate monomers and exposed to UV or EB irradiation. The results showed that the hardness of cured films were increased by increasing the functionality of monomers with excellent adhesion for all formulations but at expense of other properties involving bending and impact tests. Therefore, it can be deduce that the hardness of the curing surface coating by using EB was found to be nearly twice the hardness of the curing surface coating by using UV irradiation. Also, the best formulations which have given good chemical and mechanical properties are (mono-di) functional acrylate monomer resin under EB and (mono-tri) functional acrylate monomer resin under UV irradiation

Use of satellite erythemal UV products in analysing the global UV changes

Directory of Open Access Journals (Sweden)

I. Ialongo

2011-09-01

Full Text Available Long term changes in solar UV radiation affect global bio-geochemistry and climate. The satellite-based dataset of TOMS (Total Ozone Monitoring System and OMI (Ozone Monitoring Instrument of erythemal UV product was applied for the first time to estimate the long-term ultraviolet (UV changes at the global scale. The analysis of the uncertainty related to the different input information is presented. OMI and GOME-2 (Global Ozone Monitoring Experiment-2 products were compared in order to analyse the differences in the global UV distribution and their effect on the linear trend estimation.

The results showed that the differences in the inputs (mainly surface albedo and aerosol information used in the retrieval, affect significantly the UV change calculation, pointing out the importance of using a consistent dataset when calculating long term UV changes. The areas where these differences played a major role were identified using global maps of monthly UV changes. Despite the uncertainties, significant positive UV changes (ranging from 0 to about 5 %/decade were observed, with higher values in the Southern Hemisphere at mid-latitudes during spring-summer, where the largest ozone decrease was observed.

Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

Science.gov (United States)

Razavizadeh, Mahmoud; Jamshidi, Masoud

2016-08-01

Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

Improving radiation data quality of USDA UV-B monitoring and research program and evaluating UV decomposition in DayCent and its ecological impacts

Science.gov (United States)

Chen, Maosi

Solar radiation impacts many aspects of the Earth's atmosphere and biosphere. The total solar radiation impacts the atmospheric temperature profile and the Earth's surface radiative energy budget. The solar visible (VIS) radiation is the energy source of photosynthesis. The solar ultraviolet (UV) radiation impacts plant's physiology, microbial activities, and human and animal health. Recent studies found that solar UV significantly shifts the mass loss and nitrogen patterns of plant litter decomposition in semi-arid and arid ecosystems. The potential mechanisms include the production of labile materials from direct and indirect photolysis of complex organic matters, the facilitation of microbial decomposition with more labile materials, and the UV inhibition of microbes' population. However, the mechanisms behind UV decomposition and its ecological impacts are still uncertain. Accurate and reliable ground solar radiation measurements help us better retrieve the atmosphere composition, validate satellite radiation products, and simulate ecosystem processes. Incorporating the UV decomposition into the DayCent biogeochemical model helps to better understand long-term ecological impacts. Improving the accuracy of UV irradiance data is the goal of the first part of this research and examining the importance of UV radiation in the biogeochemical model DayCent is the goal of the second part of the work. Thus, although the dissertation is separated into two parts, accurate UV irradiance measurement links them in what follows. In part one of this work the accuracy and reliability of the current operational calibration method for the (UV-) Multi-Filter Rotating Shadowband Radiometer (MFRSR), which is used by the U.S. Department of Agriculture UV-B Monitoring and Research Program (UVMRP), is improved. The UVMRP has monitored solar radiation in the 14 narrowband UV and VIS spectral channels at 37 sites across U.S. since 1992. The improvements in the quality of the data result

Utilization of the UV laser with picosecond pulses for the formation of surface microstructures on elastomeric plastics

Science.gov (United States)

Antoszewski, B.; Tofil, S.; Scendo, M.; Tarelnik, W.

2017-08-01

Elastomeric plastics belong to a wide range of polymeric materials with special properties. They are used as construction material for seals and other components in many branches of industry and, in particular, in the biomedical industry, mechatronics, electronics and chemical equipment. The micromachining of surfaces of these materials can be used to build micro-flow, insulating, dispensing systems and chemical and biological reactors. The paper presents results of research on the effects of micro-machining of selected elastomeric plastics using a UV laser emitting picosecond pulses. The authors see the prospective application of the developed technology in the sealing technique in particular to shaping the sealing pieces co-operating with the surface of the element. The result of the study is meant to show parameters of the UV laser’s performance when producing typical components such as grooves, recesses for optimum ablation in terms of quality and productivity.

In vivo activation of human immunodeficiency virus type 1 long terminal repeat by UV type A (UV-A) light plus psoralen and UV-B light in the skin of transgenic mice

OpenAIRE

Morrey, John D; Bourn, S M; Bunch, T D; Jackson, M K; Sidwell, R W; Barrows, L R; Daynes, R A; Rosen, C A

1991-01-01

UV irradiation has been shown to activate the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) in cell culture; however, only limited studies have been described in vivo. UV light has been categorized as UV-A (400 to 315 nm), -B (315 to 280 nm), or -C (less than 280 nm); the longer wavelengths are less harmful but more penetrative. Highly penetrative UV-A radiation constitutes the vast majority of UV sunlight reaching the earth's surface but is normally harmless. UV-B ir...

Periodic nanostructures fabricated on GaAs surface by UV pulsed laser interference

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei; Huo, Dayun; Guo, Xiaoxiang; Rong, Chen; Shi, Zhenwu, E-mail: zwshi@suda.edu.cn; Peng, Changsi, E-mail: changsipeng@suda.edu.cn

2016-01-01

Graphical abstract: - Highlights: • Periodic nanostructures were fabricated on GaAs wafers by four-beam laser interference patterning which have potential applications in many fields. • Significant different results were obtained on epi-ready and homo-epitaxial GaAs substrate surfaces. • Two-pulse patterning was carried out on homo-epitaxial GaAs substrate, a noticeable morphology transformation induced by the second pulse was observed. • Temperature distribution on sample surface as a function of time and position was calculated by solving the heat diffusion equations. The calculation agrees well with the experiment results. - Abstract: In this paper, periodic nanostructures were fabricated on GaAs wafers by four-beam UV pulsed laser interference patterning. Significant different results were observed on epi-ready and homo-epitaxial GaAs substrate surfaces, which suggests GaAs oxide layer has an important effect on pulsed laser irradiation process. In the case of two-pulse patterning, a noticeable morphology transformation induced by the second pulse was observed on homo-epitaxial GaAs substrate. Based on photo-thermal mode, temperature distribution on sample surface as a function of time and position was calculated by solving the heat diffusion equations.

Occurrence, distribution and ecological risk assessment of multiple classes of UV filters in surface waters from different countries.

Science.gov (United States)

Tsui, Mirabelle M P; Leung, H W; Wai, Tak-Cheung; Yamashita, Nobuyoshi; Taniyasu, Sachi; Liu, Wenhua; Lam, Paul K S; Murphy, Margaret B

2014-12-15

Organic UV filters are common ingredients of personal care products (PCPs), but little is known about their distribution in and potential impacts to the marine environment. This study reports the occurrence and risk assessment of twelve widely used organic UV filters in surface water collected in eight cities in four countries (China, the United States, Japan, and Thailand) and the North American Arctic. The number of compounds detected, Hong Kong (12), Tokyo (9), Bangkok (9), New York (8), Los Angeles (8), Arctic (6), Shantou (5) and Chaozhou (5), generally increased with population density. Median concentrations of all detectable UV filters were ethylhexyl methoxycinnamate (EHMC) were more likely to pose a risk to fishes and also posed high risk of bleaching in hard corals in aquatic recreational areas in Hong Kong. This study is the first to report the occurrence of organic UV filters in the Arctic and provides a wider assessment of their potential negative impacts in the marine environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Selective cell culture on UV transparent polymer by F{sub 2} laser surface modification

Energy Technology Data Exchange (ETDEWEB)

Hanada, Yasutaka, E-mail: y-hanada@riken.jp [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sugioka, Koji [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawano, Hiroyuki [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tsuchimoto, Takayoshi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyamoto, Iwao [Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyawaki, Atsushi [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Midorikawa, Katsumi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

2009-09-30

A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F{sub 2} laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F{sub 2} laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

Evaluating the effects of UV-B and UV-A irradiances on plant pigments, photosynthesis and growth in Glycine max L

International Nuclear Information System (INIS)

Middleton, E.H.M.

1993-01-01

Increasing penetration of UV-B radiation to the earth's surface resulting from stratospheric ozone depletion is an important environmental concern, but plant response to UV-B irradiation has been difficult to assess. The UV-A irradiance has not been specifically measured or controlled previously. The experimental UV-A was controlled in a series of three glasshouse experiments conducted under high photosynthetic photon flux (midday PPF ≥ 1200 μmol m -2 s -1 ). Low (LT) and High (HT) daily UV-B BE irradiances (10.7; 14.1 kJ m -2 ) were utilized in two experiments, whereas treatments with different UV-B BE :UV-A ratios ( BE :UV-A ratios

A portable UV-fluorescence multispectral imaging system for the analysis of painted surfaces

Science.gov (United States)

Comelli, Daniela; Valentini, Gianluca; Nevin, Austin; Farina, Andrea; Toniolo, Lucia; Cubeddu, Rinaldo

2008-08-01

A portable fluorescence multispectral imaging system was developed and has been used for the analysis of artistic surfaces. The imaging apparatus exploits two UV lamps for fluorescence excitation and a liquid crystal tunable filter coupled to a low-noise charge coupled device as the image detector. The main features of the system are critically presented, outlining the assets, drawbacks, and practical considerations of portability. A multivariate statistical treatment of spectral data is further considered. Finally, the in situ analysis with the new apparatus of recently restored Renaissance wall paintings is presented.

Plant Responses to Increased UV-B Radiation: A Research Project

Science.gov (United States)

DAntoni, H. L.; Skiles, J. W.; Armstrong, R.; Coughlan, J.; Daleo, G.; Mayoral, A.; Lawless, James G. (Technical Monitor)

1994-01-01

because there is anecdotal evidence of plant damage on the saguaros that has been linked to increased UV radiation, and (3) the forests of Nothofagus spp. and the steppe of Patagonia where the risk of plant damage at 35S is 5% and increases to as much as 15% at 55S due to increased UV-B radiation. Measurements of UV-B radiation impinging on the surface at 55S largely exceed the predicted UV-B radiation values at 50 latitude and 0% ozone depletion. Preliminary HPLC analyses of UV-B absorbing compounds in Nothofagus antartica, N. pumilio, N. betuloides and Rumex sp. in natural conditions show species-specific patterns. The spectrum of N. antartica grown at 38S differs significantly from that of N. antartica in natural conditions in Ushuaia (55S). These results suggest that the selected main area (Patagonia) is appropriate for assessing the problem and its magnitude and that Nothofagus is appropriate for our study.

Surface modification induced by UV nanosecond Nd:YVO4 laser structuring on biometals

Science.gov (United States)

Fiorucci, M. Paula; López, Ana J.; Ramil, Alberto

2014-08-01

Laser surface texturing is a promising tool for improving metallic biomaterials performance in dental and orthopedic bone-replacing applications. Laser ablation modifies the topography of bulk material and might alter surface properties that govern the interactions with the surrounding tissue. This paper presents a preliminary evaluation of surface modifications in two biometals, stainless steel 316L and titanium alloy Ti6Al4V by UV nanosecond Nd:YVO4. Scanning electron microscopy of the surface textured by parallel micro-grooves reveals a thin layer of remelted material along the grooves topography. Furthermore, X-ray diffraction allowed us to appreciate a grain refinement of original crystal structure and consequently induced residual strain. Changes in the surface chemistry were determined by means of X-ray photoelectron spectroscopy; in this sense, generalized surface oxidation was observed and characterization of the oxides and other compounds such hydroxyl groups was reported. In case of titanium alloy, oxide layer mainly composed by TiO2 which is a highly biocompatible compound was identified. Furthermore, laser treatment produces an increase in oxide thickness that could improve the corrosion behavior of the metal. Otherwise, laser treatment led to the formation of secondary phases which might be detrimental to physical and biocompatibility properties of the material.

Improved osteoblast response to UV-irradiated PMMA/TiO2 nanocomposites with controllable wettability.

Science.gov (United States)

Shayan, Mahdis; Jung, Youngsoo; Huang, Po-Shun; Moradi, Marzyeh; Plakseychuk, Anton Y; Lee, Jung-Kun; Shankar, Ravi; Chun, Youngjae

2014-12-01

Osteoblast response was evaluated with polymethylmethacrylate (PMMA)/titanium dioxide (TiO2) nanocomposite thin films that exhibit the controllable wettability with ultraviolet (UV) treatment. In this study, three samples of PMMA/TiO2 were fabricated with three different compositional volume ratios (i.e., 25/75, 50/50, and 75/25) followed by UV treatment for 0, 4, and 8 h. All samples showed the increased hydrophilicity after UV irradiation. The films fabricated with the greater amount of TiO2 and treated with the longer UV irradiation time increased the hydrophilicity more. The partial elimination of PMMA on the surface after UV irradiation created a durable hydrophilic surface by (1) exposing higher amount of TiO2 on the surface, (2) increasing the hydroxyl groups on the TiO2 surface, and (3) producing a mesoporous structure that helps to hold the water molecules on the surface longer. The partial elimination of PMMA on the surface was confirmed by Fourier transform infrared spectroscopy. Surface profiler and atomic force microscopy demonstrated the increased surface roughness after UV irradiation. Both scanning electron microscopy and energy-dispersive X-ray spectroscopy demonstrated that particles containing calcium and phosphate elements appeared on the 8 h UV-treated surface of PMMA/TiO2 25/75 samples after 4 days soaking in Dulbecco's Modified Eagle Medium. UV treatment showed the osteoblast adhesion improved on all the surfaces. While all UV-treated hydrophilic samples demonstrated the improvement of osteoblast cell adhesion, the PMMA/TiO2 25/75 sample after 8 h UV irradiation (n = 5, P value = 0.000) represented the best cellular response as compared to other samples. UV-treated PMMA/TiO2 nanocomposite thin films with controllable surface properties represent a high potential for the biomaterials used in both orthopedic and dental applications.

Similarities in the induction of synthesis of a cell-surface polypeptide in Arthrobacter sp. by near-UV irradiation and photodynamic conditions

International Nuclear Information System (INIS)

Hoober, J.K.; Franzi, J.

1983-01-01

Irradiation of aerobic suspensions of Arthrobacter sp. with near-UV light (310-400 nm) induced synthesis of a 21 000 dalton, cell-surface polypeptide. Synthesis of this polypeptide also was induced by visible light in the presence of photodynamic dyes. Induction of the polypeptide in ear-UV light and with visible light plus dyes was inhibited by histidine. Hemin inhibited induction in near-UV light and in visible light with methylene blue, neutral red and acriflavin, which are cationic dyes, but failed to inhibit induction in visible light with rose bengal, an anionic dye. These results suggested that inhibition by hemin required electrostatically favored interaction between the anionic porphyrin and the sensitizer, and that the near-UV light effect was mediated by a cationic or neutral endogenous sensitizer. The similarities in the responses of the cells to near-UV irradiation and visible light plus dyes suggested that the mechanism of induction under the two conditions was the same. (author)

EB/UV curing market in Malaysia

Energy Technology Data Exchange (ETDEWEB)

Dahlan, Khairul Zaman; Nik Salleh, Nik Ghazali; Mahmood, Mohd Hilmi [Malaysian Inst. for Nuclear Technology Res. (MINT), Bangi (Malaysia)

1999-07-01

Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing ofprinting ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films.

EB/UV curing market in Malaysia

International Nuclear Information System (INIS)

Khairul Zaman Dahlan; Nik Ghazali Nik Salleh; Mohd Hilmi Mahmood

1999-01-01

Radiation curing of coatings of wood based products is expanding and being used for curing of coatings of table tops, parquet, wood panel, furniture, curtain railing, etc. UV curing of over print varnish is still the main application of UV curing in printing industry. However, curing of printing ink has also been extended in the printing of CD and VCD in addition to other printing such as paper, magazine, label on bottles, metal-can, etc. In the electronic industry, the manufacturer of printed circuit board is still the main consumer of UV curable resins. On the other hand, low energy electron beam machine is used mainly for cross-linking of heat shrink films

Characterization of diffraction gratings scattering in uv and ir for space applications

Science.gov (United States)

Achour, Sakina; Kuperman-Le Bihan, Quentin; Etcheto, Pierre

2017-09-01

The use of Bidirectional Scatter Distribution Function (BSDF) in space industry and especially when designing telescopes is a key feature. Indeed when speaking about space industry, one can immediately think about stray light issues. Those important phenomena are directly linked to light scattering. Standard BSDF measurement goniophotometers often have a resolution of about 0.1° and are mainly working in or close to the visible spectrum. This resolution is far too loose to characterize ultra-polished surfaces. Besides, wavelength range of BSDF measurements for space projects needs to be done far from visible range. How can we measure BSDF of ultra-polished surfaces and diffraction gratings in the UV and IR range with high resolution? We worked on developing a new goniophometer bench in order to be able to characterize scattering of ultra-polished surfaces and diffraction gratings used in everyday space applications. This ten meters long bench was developed using a collimated beam approach as opposed to goniophotometer using focused beam. Sources used for IR characterization were CO2 (10.6?m) and Helium Neon (3.39?m) lasers. Regarding UV sources, a collimated and spatially filtered UV LED was used. The detection was ensure by a photomultiplier coupled with synchronous detection as well as a MCT InSb detector. The so-built BSDF measurement instrument allowed us to measure BSDF of ultra-polished surfaces as well as diffraction gratings with an angular resolution of 0.02° and a dynamic of 1013 in the visible range. In IR as well as in UV we manage to get 109 with same angular resolution of 0.02°. The 1m arm and translation stages allows us to measure samples up to 200mm. Thanks to such a device allowing ultra-polished materials as well as diffraction gratings scattering characterization, it is possible to implement those BSDF measurements into simulation software and predict stray light issues. This is a big help for space industry engineers to apprehend stray light

UV-B Radiation Contributes to Amphibian Population Declines

Science.gov (United States)

Blaustein, Andrew

2007-05-01

UV-B (280-315 nm) radiation is the most significant biologically damaging radiation at the terrestrial surface. At the organismal level, UV-B radiation can slow growth rates, cause immune dysfunction and result in sublethal damage. UV-B radiation can lead to mutations and cell death. Over evolutionary time, UV radiation has been an important stressor on living organisms. Natural events, including impacts from comets and asteroids, volcanic activity, supernova explosions and solar flares, can cause large-scale ozone depletion with accompanying increases in UV radiation. However, these natural events are transient. Moreover, the amount of ozone damage due to natural events depends upon a number of variables, including the magnitude of the event. This is different from modern-day human-induced production of chlorofluorocarbons (CFCs) and other chemicals that deplete stratospheric ozone continuously, resulting in long-term increases in UV-B radiation at the surface of the earth. We will briefly review the effects of UV-B exposure in one group of aquatic organisms_amphibians. UV-B has been implicated as a possible factor contributing to global declines and range reductions in amphibian populations.

Effects of UV-B radiation on wax biosynthesis

International Nuclear Information System (INIS)

Barnes, J.; Paul, N.; Percy, K.; Broadbent, P.; McLaughlin, C.; Mullineaux, P.; Creissen, G.; Wellburn, A.

1994-01-01

Two genotypes of tobacco (Nicotiana tabacum L.) were exposed in controlled environment chambers to three levels of biologically effective ultraviolet-B radiation (UV-B BE ; 280-320nm): 0, 4.54 (ambient) and 5.66 (∼ 25% enhancement) kJ m -2 d -1 . After 28 days, the quantity of wax deposited on leaf surfaces was determined gravimetrically; epicuticular wax chemical composition was determined by capillary gas chromatography with homologue assignments confirmed by gas chromatography-mass spectrometry. Leaf wettability was assessed by measuring the contact angle of water droplets placed on leaf surfaces. Tobacco wax consisted of three major hydrocarbon classes: Straight-chain alkanes (C 27 -C 33 ) which comprised ∼ 59% of the hydrocarbon fraction, containing a predominance of odd-chain alkanes with C 31 as the most abundant homologue; branched-chain alkanes (C 25 -C 32 ) which comprised ∼38% of the hydrocarbon fraction with anteiso 3-methyltriacontane (C 30 ) as the predominant homologue; and fatty acids (C 14 -C 18 ) which comprised ∼ 3% of the wax. Exposure to enhanced UV-B radiation reduced the quantity of wax on the adaxial surface of the transgenic mutant, and resulted in marked changes in the chemical composition of the wax on the exposed leaf surface. Enhanced UV-B decreased the quantity of straight-chain alkanes, increased the quantity of branched-chain alkanes and fatty acids, and resulted in shifts toward shorter straight-chain lengths. Furthermore, UV-B-induced changes in wax composition were associated with increased wettability of tobacco leaf surfaces. Overall, the data are consistent with the view that UV-B radiation has a direct and fundamental effect on wax biosynthesis. Relationships between the physico-chemical nature of the leaf surface and sensitivity to UV-B radiation are discussed. (orig.)

Surface plasmon resonance spectroscopic study of UV-addressable phenylalanine sensing based on a self-assembled spirooxazine derivative monolayer

International Nuclear Information System (INIS)

Suk, Shinae; Suh, Hee-Jung; Gun An, Won; Kim, Jae-Ho; Jin, Sung-Ho; Kim, Sung-Hoon; Gal, Yeong-Soon; Koh, Kwangnak

2004-01-01

Light-addressable compounds are very interesting due to the possibilities of their practical use such as optical switches and memories or variable transmission materials. For example, transportation of phenylalanine across liposomal bilayers mediated by a photoresponsive carrier like spirooxazine through electrostatic interaction between phenylalanine and spirooxazine derivative. Thus, the spirooxazine is expected to form a UV-addressable phenylalanine sensing interface. In this study, we prepared phenylalanine sensing interface of a spirooxazine derivative by self-assembly technique and evaluated interaction between a spirooxazine moiety and phenylalanine with a surface plasmon resonance (SPR). The refractive index change of monolayer caused by interaction between a spirooxazine derivative and phenylalanine led to the SPR angle shifts upon UV irradiation. The SPR angle shift increased with increasing the concentration of phenylalanine solution. These results indicated that the spirooxazine derivative self-assembled monolayer (SAM) has an application potential for UV-addressable phenylalanine sensing

Optimizing UV Index determination from broadband irradiances

Science.gov (United States)

Tereszchuk, Keith A.; Rochon, Yves J.; McLinden, Chris A.; Vaillancourt, Paul A.

2018-03-01

A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV Index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multiscale (GEM) numerical prediction model to determine the UV Index. The basis of the investigation involves the creation of a suite of routines which employ high-spectral-resolution radiative transfer code developed to calculate UV Index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high-spectral-resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV Index. A subsequent comparison of irradiances and UV Index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310.70-330.0 and 330.03-400.00 nm is typically greater than 95 % for clear-sky conditions with associated root-mean-square relative errors of 6.4 and 4.0 %. However, underestimations of clear-sky GEM irradiances were found on the order of ˜ 30-50 % for the 294.12-310.70 nm band and by a factor of ˜ 30 for the 280.11-294.12 nm band. This underestimation can be significant for UV Index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV Index. The resultant differences in UV indices from the high-spectral-resolution irradiances and the resultant GEM broadband irradiances are typically within 0

Validation of an HPLC–UV method for the determination of digoxin residues on the surface of manufacturing equipment

Directory of Open Access Journals (Sweden)

ZORAN B. TODOROVIĆ

2009-09-01

Full Text Available In the pharmaceutical industry, an important step consists in the removal of possible drug residues from the involved equipments and areas. The cleaning procedures must be validated and methods to determine trace amounts of drugs have, therefore, to be considered with special attention. An HPLC–UV method for the determination of digoxin residues on stainless steel surfaces was developed and validated in order to control a cleaning procedure. Cotton swabs, moistened with methanol were used to remove any residues of drugs from stainless steel surfaces, and give recoveries of 85.9, 85.2 and 78.7 % for three concentration levels. The precision of the results, reported as the relative standard deviation (RSD, were below 6.3 %. The method was validated over a concentration range of 0.05–12.5 µg mL-1. Low quantities of drug residues were determined by HPLC–UV using a Symmetry C18 column (150´4.6 mm, 5 µm at 20 °C with an acetonitrile–water (28:72, v/v mobile phase at a flow rate of 1.1 mL min-1, an injection volume of 100 µL and were detected at 220 nm. A simple, selective and sensitive HPLC–UV assay for the determination of digoxin residues on stainless steel was developed, validated and applied.

Multispectral UV imaging for surface analysis of MUPS tablets with special focus on the pellet distribution

DEFF Research Database (Denmark)

Novikova, Anna; Carstensen, Jens Michael; Rades, Thomas

2016-01-01

In the present study the applicability of multispectral UV imaging in combination with multivariate image analysis for surface evaluation of MUPS tablets was investigated with respect to the differentiation of the API pellets from the excipients matrix, estimation of the drug content as well as p...... image analysis is a promising approach for the automatic quality control of MUPS tablets during the manufacturing process....

A simple UV-ozone surface treatment to enhance photocatalytic performance of TiO 2 loaded polymer nanofiber membranes

KAUST Repository

Dilpazir, S.

2016-01-29

Homogeneously dispersed titanium dioxide loaded polyacrylonitrile nanofiber membranes with increased active mass loading, Ti3+ surface defects and hydrophilicity were fabricated by combining electrospinning and UV-ozone surface treatment. The photocatalytic activity improved by a factor of ∼2 and the kinetics of photodegradation switched from pseudo-first order to pseudo-second order with increasing TiO2 content with a maximum rate constant of 20.7 h-1. © The Royal Society of Chemistry 2016.

Impact of Room Location on UV-C Irradiance and UV-C Dosage and Antimicrobial Effect Delivered by a Mobile UV-C Light Device.

Science.gov (United States)

Boyce, John M; Farrel, Patricia A; Towle, Dana; Fekieta, Renee; Aniskiewicz, Michael

2016-06-01

OBJECTIVE To evaluate ultraviolet C (UV-C) irradiance, UV-C dosage, and antimicrobial effect achieved by a mobile continuous UV-C device. DESIGN Prospective observational study. METHODS We used 6 UV light sensors to determine UV-C irradiance (W/cm2) and UV-C dosage (µWsec/cm2) at various distances from and orientations relative to the UV-C device during 5-minute and 15-minute cycles in an ICU room and a surgical ward room. In both rooms, stainless-steel disks inoculated with methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and Clostridium difficile spores were placed next to sensors, and UV-C dosages and log10 reductions of target organisms achieved during 5-minute and 15-minute cycles were determined. Mean irradiance and dosage readings were compared using ANOVA. RESULTS Mean UV-C irradiance was nearly 1.0E-03 W/cm2 in direct sight at a distance of 1.3 m (4 ft) from the device but was 1.12E-05 W/cm2 on a horizontal surface in a shaded area 3.3 m (10 ft) from the device (P4 to 1-3 for MRSA, >4 to 1-2 for VRE and >4 to 0 log10 for C. difficile spores, depending on the distance from, and orientation relative to, the device with 5-minute and 15-minute cycles. CONCLUSION UV-C irradiance, dosage, and antimicrobial effect received from a mobile UV-C device varied substantially based on location in a room relative to the UV-C device. Infect Control Hosp Epidemiol 2016;37:667-672.

Influence of uvA on the erythematogenic and therapeutic effects of uvB irradiation in psoriasis; photoaugmentation effects

International Nuclear Information System (INIS)

Boer, J.; Schothorst, A.A.; Suurmond, D.

1981-01-01

The effect of repeated exposure to an additive dose of long ultraviolet (uvA) radiation on the erythemogenic and therapeutic effects of middle ultraviolet (uvB) irradiation was investigated in 8 patients with psoriasis. The surface of the backs of these patients was divided into 2 parts, 1 of which received only uvB irradiation 4 times a week and the other uvA + uvB. uvB was provided by Philips TL-12 lamps and uvA by glass-filtered Philips TL-09 lamps. uvA was held constantly at 10 J/cm2, whereas uvB alone were evaluated by 4 tests during the treatment to determine the minimal erythema dose (MED). Test I (at the start of the therapy) showed a photoaugmentative effect which was no longer apparent in Test III (third week). Test III showed a reversal of the ratios of the MEDs of the sites irradiated with the uvA + uvB and uvB (MED A + B/MED B). This is ascribed to the marked pigmentation which appeared after repeated irradiation with the uvA + uvB combination. Comparison showed for the improvement of the psoriasis no distinct differences between uvA + uvB irradiation and uvB alone, but the former had the cosmetic advantage of giving pleasing tan

Tailor-made dimensions of diblock copolymer truncated micelles on a solid by UV irradiation.

Science.gov (United States)

Liou, Jiun-You; Sun, Ya-Sen

2015-09-28

We investigated the structural evolution of truncated micelles in ultrathin films of polystyrene-block-poly(2-vinylpyridine), PS-b-P2VP, of monolayer thickness on bare silicon substrates (SiOx/Si) upon UV irradiation in air- (UVIA) and nitrogen-rich (UVIN) environments. The structural evolution of micelles upon UV irradiation was monitored using GISAXS measurements in situ, while the surface morphology was probed using atomic force microscopy ex situ and the chemical composition using X-ray photoelectron spectroscopy (XPS). This work provides clear evidence for the interpretation of the relationship between the structural evolution and photochemical reactions in PS-b-P2VP truncated micelles upon UVIA and UVIN. Under UVIA treatment, photolysis and cross-linking reactions coexisted within the micelles; photolysis occurred mainly at the top of the micelles, whereas cross-linking occurred preferentially at the bottom. The shape and size of UVIA-treated truncated micelles were controlled predominantly by oxidative photolysis reactions, which depended on the concentration gradient of free radicals and oxygen along the micelle height. Because of an interplay between photolysis and photo-crosslinking, the scattering length densities (SLD) of PS and P2VP remained constant. In contrast, UVIN treatments enhanced the contrast in SLD between the PS shell and the P2VP core as cross-linking dominated over photolysis in the presence of nitrogen. The enhancement of the SLD contrast was due to the various degrees of cross-linking under UVIN for the PS and P2VP blocks.

Effect of UV on building materials in New Zealand

International Nuclear Information System (INIS)

Bennett, A.F.

1993-01-01

Building materials can be divided into two main classes; organic or polymeric based and inorganic materials. Inorganic materials are in most cases largely unaffected by UV radiation. Many common polymers have bonds sensitive to radiation in the UV region. Absorption of radiation of these wavelengths will lead to excitation of electrons which can lead to isomerisation, chain scissors, cross linking and free radical formation. It is worth noting that the effects of UV radiation are always acting synergistically with other environmental effects. (author). 4 refs., 2 tabs

UV production of methane from surface and sedimenting IDPs on Mars in light of REMS data and with insights for TGO

Science.gov (United States)

Moores, John E.; Smith, Christina L.; Schuerger, Andrew C.

2017-11-01

This paper refines model predictions for the production of methane from UV-irradiated interplanetary dust particles (IDPs) now that the Rover Environmental Monitoring Station (REMS) instrument onboard the Mars Science Laboratory (MSL) Rover has made the first measurements of the UV environment on the surface of Mars, at Gale Crater. Once these measurements are included in a UV radiative transfer model, we find that modelled UV sol-integrated energies across the planet are lower than pre-measurement estimates by 35% on average, considering all latitudes and seasons. This reduction, in turn, reduces the predicted production of methane from individual accreting IDPs, extending their lifetimes and increasing the surface concentration of organics that must accumulate in order to emit sufficient methane to balance the accretion of organic compounds to Mars. Emission from reasonable accumulations of IDPs could range up to ∼7.9 × 10-4 ppbv sol-1. Richer deposits of organic carbon at the surface may emit methane at no more than 3.9 ppbv sol-1. An examination of IDP-derived methane production during atmospheric settling indicates that no more than 0.32% of organic carbon from meteor streams may be deposited in the atmosphere. Thus, such a process cannot explain either the spikes observed in methane nor the low equilibrium values observed by MSL. Instead, this discrepancy may be explained if geographical and vertical distribution will be an important input for models attempting to understand the results to be derived from the Trace Gas Orbiter (TGO) mission that will map methane concentrations in the martian atmosphere in 2018 at 0.01 ppbv.

UV-durable superhydrophobic textiles with UV-shielding properties by coating fibers with ZnO/SiO2 core/shell particles

Science.gov (United States)

Xue, Chao-Hua; Yin, Wei; Jia, Shun-Tian; Ma, Jian-Zhong

2011-10-01

ZnO/SiO2 core/shell particles were fabricated by successive coating of multilayer polyelectrolytes and then a SiO2 shell onto ZnO particles. The as-prepared ZnO/SiO2 core/shell particles were coated on poly(ethylene terephthalate) (PET) textiles, followed by hydrophobization with hexadecyltrimethoxysilane, to fabricate superhydrophobic surfaces with UV-shielding properties. Transmission electron microscopy and ζ potential analysis were employed to evidence the fabrication of ZnO/SiO2 core/shell particles. Scanning electron microscopy and thermal gravimetric analysis were conducted to investigate the surface morphologies of the textile and the coating of the fibers. Ultraviolet-visible spectrophotometry and contact angle measurement indicated that the incorporation of ZnO onto fibers imparted UV-blocking properties to the textile surface, while the coating of SiO2 shell on ZnO prohibited the photocatalytic degradation of hexadecyltrimethoxysilane by ZnO, making the as-treated PET textile surface show stable superhydrophobicity with good UV-shielding properties.

TEMIS UV product validation using NILU-UV ground-based measurements in Thessaloniki, Greece

Science.gov (United States)

Zempila, Melina-Maria; van Geffen, Jos H. G. M.; Taylor, Michael; Fountoulakis, Ilias; Koukouli, Maria-Elissavet; van Weele, Michiel; van der A, Ronald J.; Bais, Alkiviadis; Meleti, Charikleia; Balis, Dimitrios

2017-06-01

This study aims to cross-validate ground-based and satellite-based models of three photobiological UV effective dose products: the Commission Internationale de l'Éclairage (CIE) erythemal UV, the production of vitamin D in the skin, and DNA damage, using high-temporal-resolution surface-based measurements of solar UV spectral irradiances from a synergy of instruments and models. The satellite-based Tropospheric Emission Monitoring Internet Service (TEMIS; version 1.4) UV daily dose data products were evaluated over the period 2009 to 2014 with ground-based data from a Norsk Institutt for Luftforskning (NILU)-UV multifilter radiometer located at the northern midlatitude super-site of the Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki (LAP/AUTh), in Greece. For the NILU-UV effective dose rates retrieval algorithm, a neural network (NN) was trained to learn the nonlinear functional relation between NILU-UV irradiances and collocated Brewer-based photobiological effective dose products. Then the algorithm was subjected to sensitivity analysis and validation. The correlation of the NN estimates with target outputs was high (r = 0. 988 to 0.990) and with a very low bias (0.000 to 0.011 in absolute units) proving the robustness of the NN algorithm. For further evaluation of the NILU NN-derived products, retrievals of the vitamin D and DNA-damage effective doses from a collocated Yankee Environmental Systems (YES) UVB-1 pyranometer were used. For cloud-free days, differences in the derived UV doses are better than 2 % for all UV dose products, revealing the reference quality of the ground-based UV doses at Thessaloniki from the NILU-UV NN retrievals. The TEMIS UV doses used in this study are derived from ozone measurements by the SCIAMACHY/Envisat and GOME2/MetOp-A satellite instruments, over the European domain in combination with SEVIRI/Meteosat-based diurnal cycle of the cloud cover fraction per 0. 5° × 0. 5° (lat × long) grid cells. TEMIS

TEMIS UV product validation using NILU-UV ground-based measurements in Thessaloniki, Greece

Directory of Open Access Journals (Sweden)

M.-M. Zempila

2017-06-01

Full Text Available This study aims to cross-validate ground-based and satellite-based models of three photobiological UV effective dose products: the Commission Internationale de l'Éclairage (CIE erythemal UV, the production of vitamin D in the skin, and DNA damage, using high-temporal-resolution surface-based measurements of solar UV spectral irradiances from a synergy of instruments and models. The satellite-based Tropospheric Emission Monitoring Internet Service (TEMIS; version 1.4 UV daily dose data products were evaluated over the period 2009 to 2014 with ground-based data from a Norsk Institutt for Luftforskning (NILU-UV multifilter radiometer located at the northern midlatitude super-site of the Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki (LAP/AUTh, in Greece. For the NILU-UV effective dose rates retrieval algorithm, a neural network (NN was trained to learn the nonlinear functional relation between NILU-UV irradiances and collocated Brewer-based photobiological effective dose products. Then the algorithm was subjected to sensitivity analysis and validation. The correlation of the NN estimates with target outputs was high (r = 0. 988 to 0.990 and with a very low bias (0.000 to 0.011 in absolute units proving the robustness of the NN algorithm. For further evaluation of the NILU NN-derived products, retrievals of the vitamin D and DNA-damage effective doses from a collocated Yankee Environmental Systems (YES UVB-1 pyranometer were used. For cloud-free days, differences in the derived UV doses are better than 2 % for all UV dose products, revealing the reference quality of the ground-based UV doses at Thessaloniki from the NILU-UV NN retrievals. The TEMIS UV doses used in this study are derived from ozone measurements by the SCIAMACHY/Envisat and GOME2/MetOp-A satellite instruments, over the European domain in combination with SEVIRI/Meteosat-based diurnal cycle of the cloud cover fraction per 0. 5° × 0. 5�

UV patterned nanoporous solid-liquid core waveguides

DEFF Research Database (Denmark)

Gopalakrishnan, Nimi; Sagar, Kaushal Shashikant; Christiansen, Mads Brøkner

2010-01-01

Nanoporous Solid-Liquid core waveguides were prepared by UV induced surface modification of hydrophobic nanoporous polymers. With this method, the index contrast (delta n = 0.20) is a result of selective water infiltration. The waveguide core is defined by UV light, rendering the exposed part...

A simple way to an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding property.

Science.gov (United States)

Ren, Guina; Song, Yuanming; Li, Xiangming; Wang, Bo; Zhou, Yanli; Wang, Yuyan; Ge, Bo; Zhu, Xiaotao

2018-07-15

Development of an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding by a simple method is highly desirable, yet it remains a challenge that current technologies have been unable to fully address. Herein, the original fabric is immersed into the solution containing ZnO nanoparticle and PDMS (polydimethylsiloxane), and the fiber surfaces are uniformly covered by a ZnO-PDMS layer after thermal treatment at 110 °C for 30 min. Droplets of water and corrosive liquids including strong acid, strong alkali, and saturated salt solution display sphere shape on the ZnO-PDMS coated fabric surface. The stable binding of ZnO-PDMS layer onto the fibers allows for the fabric coating with robust superhydrophobicity, and the coated fabric still displays superhydrophobicity after hand twisting, knife scratching, finger touching, and even cycles of sandpaper abrasion. The ZnO-PDMS coated fabric can also keep its superhydrophobic property when exposed to long term UV illumination, demonstrating its UV resistance. Moreover, the uniformly distribution of ZnO nanoparticles on fibers allows the ZnO-PDMS coated fabric to display UV shielding property. Copyright © 2018 Elsevier Inc. All rights reserved.

Physiological limit of the daily endogenous cholecalciferol synthesis from UV light in cattle

DEFF Research Database (Denmark)

Hymøller, L.; Jensen, S. K.; Kaas, P.

2017-01-01

The link between UV light (sunlight) and endogenous cholecalciferol (vitamin D3) synthesis in the skin of humans has been known for more than a 100 years, since doctors for the first time successfully used UV light to cure rickets in children. Years later, it was shown that UV light also had...

Development of UV absorbing PET through Electron Irradiation

International Nuclear Information System (INIS)

Kim, Jung Woo; Lee, Na Eun; Lim, Hyung San; Park, Yang Jeong; Cho, Sung Oh

2017-01-01

Experiment to increase UV absorbance through electron beam irradiation on PET was performed. Moreover, surface hardness and roughness of each sample were observed to find the key factor increasing UV absorbance. PET sheets were irradiated with an electron beam at various fluences. The irradiated samples, as well as pristine sample, were subjected to UV-visible spectral study(UV-Vis), pencil hardness test, and scanning electron microscopy(SEM) experiment. In this study, PET samples irradiated at several conditions were analyzed through various measurements. UV absorbance-another meaning of transmittance in this study- of irradiated PET sample increased compared with pristine sample as fluence was increased in UV-Visible spectroscopy experiment.

Light-induced cross-linking and post-cross-linking modification of polyglycidol.

Science.gov (United States)

Marquardt, F; Bruns, M; Keul, H; Yagci, Y; Möller, M

2018-02-08

The photoinduced radical generation process has received renewed interest due to its economic and ecological appeal. Herein the light-induced cross-linking of functional polyglycidol and its post-cross-linking modification are presented. Linear polyglycidol was first functionalized with a tertiary amine in a two-step reaction. Dimethylaminopropyl functional polyglycidol was cross-linked in a UV-light mediated reaction with camphorquinone as a type II photoinitiator. The cross-linked polyglycidol was further functionalized by quaternization with various organoiodine compounds. Aqueous dispersions of the cross-linked polymers were investigated by means of DLS and zeta potential measurements. Polymer films were evaluated by DSC and XPS.

UV-induced N2O emission from plants

DEFF Research Database (Denmark)

Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

2014-01-01

investigate for the fi rst time N 2 O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted fi eld site measurements to investigate N 2 O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory...... magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N 2 O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process...

Far-UV photochemical bond cleavage of n-amyl nitrite: bypassing a repulsive surface.

Science.gov (United States)

Minitti, Michael P; Zhang, Yao; Rosenberg, Martin; Brogaard, Rasmus Y; Deb, Sanghamitra; Sølling, Theis I; Weber, Peter M

2012-01-19

We have investigated the deep-UV photoinduced, homolytic bond cleavage of amyl nitrite to form NO and pentoxy radicals. One-color multiphoton ionization with ultrashort laser pulses through the S(2) state resonance gives rise to photoelectron spectra that reflect ionization from the S(1) state. Time-resolved pump-probe photoionization measurements show that upon excitation at 207 nm, the generation of NO in the v = 2 state is delayed, with a rise time of 283 (16) fs. The time-resolved mass spectrum shows the NO to be expelled with a kinetic energy of 1.0 eV, which is consistent with dissociation on the S(1) state potential energy surface. Combined, these observations show that the first step of the dissociation reaction involves an internal conversion from the S(2) to the S(1) state, which is followed by the ejection of the NO radical on the predissociative S(1) state potential energy surface.

UV Treatment of the Stabilizing Shell for Improving the Photostability of Silver Nanoparticles

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Silvia Rinaldi

2016-01-01

Full Text Available Silver nanoparticles or nanoclusters are quite sensitive to light exposure. In particular, irradiation in the localized surface plasmon resonance (LSPR region brings about a drastic modification of their optical properties due to growth and reshaping of the nanoparticles. In order to obtain luminescent colloids, small silver colloidal nanoparticles were prepared in chloroform using vinylpyrrolidone oligomers as capping agent and their luminescence properties were used to control their stability upon prolonged exposure to visible light. The polymeric shell around the metal clusters was hardened through photo-cross-linking by UV light. This process did not alter the morphology and the optical properties of the nanoparticles but greatly improved the particle photostability as confirmed also by confocal laser scanning microscopy measurements. The data clearly show that UV curing of the stabilizing layer could be a simple postsynthetic procedure to obtain materials with stable properties.

Complementary UV-Absorption of Mycosporine-like Amino Acids and Scytonemin is Responsible for the UV-Insensitivity of Photosynthesis in Nostoc flagelliforme

Science.gov (United States)

Ferroni, Lorenzo; Klisch, Manfred; Pancaldi, Simonetta; Häder, Donat-Peter

2010-01-01

Mycosporine-like amino acids (MAAs) and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW−1), concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm). The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315–400 nm) and UV-B (280–320 nm) range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments. PMID:20161974

Complementary UV-Absorption of Mycosporine-like Amino Acids and Scytonemin is Responsible for the UV-Insensitivity of Photosynthesis in Nostoc flagelliforme

Directory of Open Access Journals (Sweden)

Donat-Peter Häder

2010-01-01

Full Text Available Mycosporine-like amino acids (MAAs and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW-1, concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm. The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315–400 nm and UV-B (280–320 nm range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments.

Validation of an HPLC-UV method for the determination of ceftriaxone sodium residues on stainless steel surface of pharmaceutical manufacturing equipments.

Science.gov (United States)

Akl, Magda A; Ahmed, Mona A; Ramadan, Ahmed

2011-05-15

In pharmaceutical industry, an important step consists in the removal of possible drug residues from the involved equipments and areas. The cleaning procedures must be validated and methods to determine trace amounts of drugs have, therefore, to be considered with special attention. An HPLC-UV method for the determination of ceftriaxone sodium residues on stainless steel surface was developed and validated in order to control a cleaning procedure. Cotton swabs, moistened with extraction solution (50% water and 50% mobile phase), were used to remove any residues of drugs from stainless steel surfaces, and give recoveries of 91.12, 93.8 and 98.7% for three concentration levels. The precision of the results, reported as the relative standard deviation (RSD), were below 1.5%. The method was validated over a concentration range of 1.15-6.92 μg ml(-1). Low quantities of drug residues were determined by HPLC-UV using a Hypersil ODS 5 μm (250×4.6 mm) at 50 °C with an acetonitrile:water:pH 7:pH 5 (39-55-5.5-0.5) mobile phase at flow rate of 1.5 ml min(-1), an injection volume of 20 μl and were detected at 254 nm. A simple, selective and sensitive HPLC-UV assay for the determination of ceftriaxone sodium residues on stainless steel surfaces was developed, validated and applied. Copyright © 2011 Elsevier B.V. All rights reserved.

Risks of increased UV-B radiation for humans

International Nuclear Information System (INIS)

Przybilla, B.; Eberlein-Koenig, B.; Bergner, T.

1994-01-01

If not compensated in any way, depletion of the stratospheric ozone layer leads to an increase of UV-B radiation at the earth's surface, especially towards the short-wave range, which is biologically the more active. The most concerning effect here is that of UV-B induced skin reactions, in particular malignant skintumors (malignant melanoma, spinocellular carcinoma, basalioma), whose incidence is expected to increase in future. As some photoreactions can be inhibited or enhanced also by radiation outside their action spectrum, it is possible for changes in solar spectral radiation flux density to influence photo-induced reactions that are driven at wavelengths outside the UV-B range. The authors have performed studies for developing methods of quantifying individual UV sensitivity. In vitro studies have shown that UV-A dependent photoreactions can be partly inhibited by UV-B. A number of drugs, as well as sulphites, which are used as preservatives amongst other things, have been shown to have phototoxic properties that may be relevant to photocarcinogenesis. Irradiation tests on cell cultures for different UV-B ranges have shown that irradiation at shorter wavelengths leads to a stronger release of proinflammatory cytokines that ar longer wavelengths with the same dose. Altogether it can be said that despite compelling theoretical evidence it is not easily possible to predict the actual consequences of an increase in particular of short-wave UV-B radiation at the earth's surface. The assumed effects must be examined individually by appropriate methods. (orig.) [de

UV-induced carbon monoxide emission from sand and living vegetation

DEFF Research Database (Denmark)

Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

2012-01-01

The global burden of carbon monoxide, CO, is rather uncertain. In this paper we address the potential of UV-induced CO emission by terrestrial surfaces. Real-time measurements of [CO] were made with a cavity enhanced laser connected in closed loop to either an ecosystem chamber or a leaf scale...... chamber. Sand and leaves of all examined plant species exhibited emission of CO in response to artificial UV-radiation and the UV-component of natural solar radiation. The UV-induced rate of CO emission exhibited a rather low dependence on temperature, indicating an abiotic process. The emission of CO...... in response to the UV-component of natural solar radiation was also evident at the ecosystem scale. When scaled to the global level, the UV-induced emission of CO by the major types of terrestrial surfaces, living leaves and soil (here represented by sand), amounts up to 28 Tg yr−1. This source has...

Comparative researches concerning cleaning chosen construction materials surface layer using UV and IR laser radiation

International Nuclear Information System (INIS)

Napadlek, W.; Marczak, J.; Kubicki, J.; Szudrowicz, M.

2002-01-01

The paper presents comparative research studies of cleaning out of deposits and pollution disposals on different constructional materials like; steel, cast iron, aluminium, copper by using UV and IR laser radiation of wavelength λ =1.064 μm; λ = 0.532 μm; λ = 0.355 μm and λ = 0.266 μm and also impulse laser TEA CO 2 at radiation λ = 10.6 μm were used for the experiments. Achieved experimental results gave us basic information on parameters and conditions and application of each used radiation wavelength. Each kind of pollution and base material should be individually treated, selecting the length of wave and radiation energy density. Laser microtreatment allows for broad cleaning application of the surface of constructional materials as well as may be used in future during manufacturing processes as: preparation of surface for PVD technology, galvanotechnics, cleaning of the surface of machine parts etc. (author)

Photodegradation and toxicity changes of antibiotics in UV and UV/H2O2 process

International Nuclear Information System (INIS)

Yuan Fang; Hu Chun; Hu Xuexiang; Wei Dongbin; Chen Yong; Qu Jiuhui

2011-01-01

The photodegradation of three antibiotics, oxytetracycline (OTC), doxycycline (DTC), and ciprofloxacin (CIP) in UV and UV/H 2 O 2 process was investigated with a low-pressure UV lamp system. Experiments were performed in buffered ultrapure water (UW), local surface water (SW), and treated water from local municipal drinking water treatment plant (DW) and wastewater treatment plant (WW). The efficiency of UV/H 2 O 2 process was affected by water quality. For all of the three selected antibiotics, the fastest degradation was observed in DW, and the slowest degradation occurred in WW. This phenomenon can be explained by R OH,UV , defined as the experimentally determined ·OH radical exposure per UV fluence. The R OH,UV values represent the background ·OH radical scavenging in water matrix, obtained by the degradation of para-chlorobenzoic acid (pCBA), a probe compound. In natural water, the indirect degradation of CIP did not significantly increase with the addition of H 2 O 2 due to its effective degradation by UV direct photolysis. Moreover, the formation of several photoproducts and oxidation products of antibiotics in UV/H 2 O 2 process was identified using GC-MS. Toxicity assessed by Vibrio fischer (V. fischer), was increased in UV photolysis, for the photoproducts still preserving the characteristic structure of the parent compounds. While in UV/H 2 O 2 process, toxicity increased first, and then decreased; nontoxic products were formed by the oxidation of ·OH radical. In this process, detoxification was much easier than mineralization for the tested antibiotics, and the optimal time for the degradation of pollutants in UV/H 2 O 2 process would be determined by parent compound degradation and toxicity changes.

UV laser ablation of intraocular lenses: SEM and AFM microscopy examination of the biomaterial surface

International Nuclear Information System (INIS)

Spyratou, E.; Asproudis, I.; Tsoutsi, D.; Bacharis, C.; Moutsouris, K.; Makropoulou, M.; Serafetinides, A.A.

2010-01-01

Several new materials and patterns are studied for the formation and etching of intraocular lenses (IOLs), in order to improve their optical properties, to reduce the diffractive aberrations and to decrease the incidence of posterior capsular opacification. The aim of this study is to investigate the use of UV (λ = 266 nm) laser pulses to ablate the intraocular lenses materials, and thus to provide an alternative to conventional surface shaping techniques for IOLs fabrication. Ablation experiments were conducted using various polymer substrates of hydrophobic acrylic IOLs and PMMA IOLs. We investigated the ablation efficiency and the morphology of the ablated area by imaging the surface modification with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The morphological appearance of IOL samples reveals the effect of a photochemical and photothermal ablation mechanism.

UV laser ablation of intraocular lenses: SEM and AFM microscopy examination of the biomaterial surface

Energy Technology Data Exchange (ETDEWEB)

Spyratou, E., E-mail: ellas5@central.ntua.gr [National Technical University of Athens, School of Applied Mathematical and Physical Sciences, Department of Physics, Zografou Campus, Athens, 15780 (Greece); Asproudis, I. [Department of Ophthalmology, University Hospital of Ioannina, Ioannina, 45110 (Greece); Tsoutsi, D. [Department of Chemistry, University of Ioannina, Ioannina, 45110 (Greece); Bacharis, C.; Moutsouris, K.; Makropoulou, M.; Serafetinides, A.A. [National Technical University of Athens, School of Applied Mathematical and Physical Sciences, Department of Physics, Zografou Campus, Athens, 15780 (Greece)

2010-02-01

Several new materials and patterns are studied for the formation and etching of intraocular lenses (IOLs), in order to improve their optical properties, to reduce the diffractive aberrations and to decrease the incidence of posterior capsular opacification. The aim of this study is to investigate the use of UV ({lambda} = 266 nm) laser pulses to ablate the intraocular lenses materials, and thus to provide an alternative to conventional surface shaping techniques for IOLs fabrication. Ablation experiments were conducted using various polymer substrates of hydrophobic acrylic IOLs and PMMA IOLs. We investigated the ablation efficiency and the morphology of the ablated area by imaging the surface modification with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The morphological appearance of IOL samples reveals the effect of a photochemical and photothermal ablation mechanism.

Skin Cancer and UV Protection

Directory of Open Access Journals (Sweden)

Tarbuk Anita

2016-03-01

Full Text Available The incidence of skin cancer is increasing by epidemic proportions. Basal cell cancer remains the most common skin neoplasm, and simple excision is generally curative. On the other hand, aggressive local growth and metastasis are common features of malignant melanoma, which accounts for 75% of all deaths associated with skin cancer. The primary cause of skin cancer is long exposure to solar ultraviolet radiation (UV-R crossed with the amount of skin pigmentation and family genetics. It is believed that in childhood and adolescence, 80% of UV-R gets absorbed while in the remaining, 20 % gets absorbed later in the lifetime. This suggests that proper and early photoprotection may reduce the risk of subsequent occurrence of skin cancer. Reducing the exposure time to sunlight, using sunscreens and protective textiles are the three ways of UV protection. Most people think that all the clothing will protect them, but it does not provide full sun screening properties. Literature sources claim that only 1/3 of the spring and summer collections tested give off proper UV protection. This is very important during the summer months, when UV index is the highest. Fabric UV protection ability highly depends on large number of factors such as type of fiber, fabric surface, construction, porosity, density, moisture content, type and concentration of dyestuff, fluorescent whitening agents, UV-B protective agents (UV absorbers, as well as nanoparticles, if applied. For all of these reasons, in the present paper, the results of UV protecting ability according to AS/NZS 4399:1996 will be discussed to show that standard clothing materials are not always adequate to prevent effect of UV-R to the human skin; and to suggest the possibilities for its improvement for this purpose enhancing light conversion and scattering. Additionally, the discrepancy in UV protection was investigated in distilled water as well as Adriatic Sea water.

UV Irradiance Enhancements by Scattering of Solar Radiation from Clouds

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Uwe Feister

2015-08-01

Full Text Available Scattering of solar radiation by clouds can reduce or enhance solar global irradiance compared to cloudless-sky irradiance at the Earth’s surface. Cloud effects to global irradiance can be described by Cloud Modification Factors (CMF. Depending on strength and duration, irradiance enhancements affect the energy balance of the surface and gain of solar power for electric energy generation. In the ultraviolet region, they increase the risk for damage to living organisms. Wavelength-dependent CMFs have been shown to reach 1.5 even in the UV-B region at low altitudes. Ground-based solar radiation measurements in the high Andes region at altitudes up to 5917 m a.s.l showed cloud-induced irradiance enhancements. While UV-A enhancements were explained by cloud scattering, both radiation scattering from clouds and Negative Ozone Anomalies (NOA have been discussed to have caused short-time enhancement of UV-B irradiance. Based on scenarios using published CMF and additional spectroradiometric measurements at a low-altitude site, the contribution of cloud scattering to the UV-B irradiance enhancement in the Andes region has been estimated. The range of UV index estimates converted from measured UV-B and UV-A irradiance and modeled cloudless-sky ratios UV-B/erythemal UV is compatible with an earlier estimate of an extreme UV index value of 43 derived for the high Andes.

Light Conversion and Scattering in UV Protective Textiles

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Grancarić Ana Marija

2014-12-01

Full Text Available The primary cause of skin cancer is believed to be a long exposure to solar ultraviolet radiation (UV-R crossed with the amount of skin pigmentation in the population. It is believed that in childhood and adolescence 80% of UV-R gets absorbed, whilst in the remaining 20% gets absorbed later in the lifetime. This suggests that proper and early photoprotection may reduce the risk of subsequent occurrence of skin cancer. Textile and clothing are the most suitable interface between environment and human body. It can show UV protection, but in most cases it does not provide full sun screening properties. UV protection ability highly depends on large number of factors such as type of fibre, fabric surface and construction, type and concentration of dyestuff, fluorescent whitening agent (FWA, UV-B protective agents, as well as nanoparticles, if applied. Based on electronically excited state by energy of UV-R (usually 340-370 nm, the molecules of FWAs show the phenomenon of fluorescence giving to white textiles high whiteness of outstanding brightness by reemitting the energy at the blue region (typically 420-470 nm of the spectrum. By absorbing UV-A radiation, optical brightened fabrics transform this radiation into blue fluorescence, which leads to better UV protection. Natural zeolites are rock-forming, microporous silicate minerals. Applied as nanoparticles to textile surface, it scatters the UV-R resulting in lower UV-A and UV-B transmission. If applied with other UV absorbing agents, e.g. FWAs, synergistic effect occurs. Silicones are inert, synthetic compounds with a variety of forms and uses. It provides a unique soft touch, is very resistant to washing and improves the property of fabric to protect against UV radiation. Therefore, the UV protective properties of cotton fabric achieved by light conversion and scattering was researched in this paper. For that purpose, the stilbene-derived FWAs were applied on cotton fabric in wide concentration

Ecological responses to UV radiation: interactions between the biological effects of UV on plants and on associated organisms.

Science.gov (United States)

Paul, Nigel D; Moore, Jason P; McPherson, Martin; Lambourne, Cathryn; Croft, Patricia; Heaton, Joanna C; Wargent, Jason J

2012-08-01

Solar ultraviolet (UV)-B radiation (280-315 nm) has a wide range of effects on terrestrial ecosystems, yet our understanding of how UV-B influences the complex interactions of plants with pest, pathogen and related microorganisms remains limited. Here, we report the results of a series of experiments in Lactuca sativa which aimed to characterize not only key plant responses to UV radiation in a field environment but also consequential effects for plant interactions with a sap-feeding insect, two model plant pathogens and phylloplane microorganism populations. Three spectrally modifying filters with contrasting UV transmissions were used to filter ambient sunlight, and when compared with our UV-inclusive filter, L. sativa plants grown in a zero UV-B environment showed significantly increased shoot fresh weight, reduced foliar pigment concentrations and suppressed population growth of green peach aphid (Myzus persicae). Plants grown under a filter which allowed partial transmission of UV-A radiation and negligible UV-B transmission showed increased density of leaf surface phylloplane microbes compared with the UV-inclusive treatment. Effects of UV treatment on the severity of two plant pathogens, Bremia lactucae and Botrytis cinerea, were complex as both the UV-inclusive and zero UV-B filters reduced the severity of pathogen persistence. These results are discussed with reference to known spectral responses of plants, insects and microorganisms, and contrasted with established fundamental responses of plants and other organisms to solar UV radiation, with particular emphasis on the need for future integration between different experimental approaches when investigating the effects of solar UV radiation. Copyright © Physiologia Plantarum 2011.

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

Directory of Open Access Journals (Sweden)

J. W. Krzyscin

2004-04-01

Full Text Available The daily doses of the erythemally weighted UV radiation are reconstructed for three sites in Central Europe: Belsk-Poland (1966–2001, Hradec Kralove-Czech Republic (1964–2001, and Tõravere-Estonia (1967–2001 to discuss the UV climatology and the long-term changes of the UV-B radiation since the mid 1960s. Various reconstruction models are examined: a purely statistical model based on the Multivariate Adaptive Regression Splines (MARS methodology, and a hybrid model combining radiative transfer model calculations with empirical estimates of the cloud effects on the UV radiation. Modeled long-term variations of the surface UV doses appear to be in a reasonable agreement with the observed ones. A simple quality control procedure is proposed to check the homogeneity of the biometer and pyranometer data. The models are verified using the results of UV observations carried out at Belsk since 1976. MARS provides the best estimates of the UV doses, giving a mean difference between the modeled and observed monthly means equal to 0.6±2.5%. The basic findings are: similar climatological forcing by clouds for all considered stations (~30% reduction in the surface UV, long-term variations in UV monthly doses having the same temporal pattern for all stations with extreme low monthly values (~5% below overall mean level at the end of the 1970s and extreme high monthly values (~5% above overall mean level in the mid 1990s, regional peculiarities in the cloud long-term forcing sometimes leading to extended periods with elevated UV doses, recent stabilization of the ozone induced UV long-term changes being a response to a trendless tendency of total ozone since the mid 1990s. In the case of the slowdown of the total ozone trend over Northern Hemisphere mid-latitudes it seems that clouds will appear as the most important modulator of the UV radiation both in long- and short-time scales over next decades. Key words. Atmospheric composition and structure

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

Directory of Open Access Journals (Sweden)

J. W. Krzyscin

2004-04-01

Full Text Available The daily doses of the erythemally weighted UV radiation are reconstructed for three sites in Central Europe: Belsk-Poland (1966–2001, Hradec Kralove-Czech Republic (1964–2001, and Tõravere-Estonia (1967–2001 to discuss the UV climatology and the long-term changes of the UV-B radiation since the mid 1960s. Various reconstruction models are examined: a purely statistical model based on the Multivariate Adaptive Regression Splines (MARS methodology, and a hybrid model combining radiative transfer model calculations with empirical estimates of the cloud effects on the UV radiation. Modeled long-term variations of the surface UV doses appear to be in a reasonable agreement with the observed ones. A simple quality control procedure is proposed to check the homogeneity of the biometer and pyranometer data. The models are verified using the results of UV observations carried out at Belsk since 1976. MARS provides the best estimates of the UV doses, giving a mean difference between the modeled and observed monthly means equal to 0.6±2.5%. The basic findings are: similar climatological forcing by clouds for all considered stations (~30% reduction in the surface UV, long-term variations in UV monthly doses having the same temporal pattern for all stations with extreme low monthly values (~5% below overall mean level at the end of the 1970s and extreme high monthly values (~5% above overall mean level in the mid 1990s, regional peculiarities in the cloud long-term forcing sometimes leading to extended periods with elevated UV doses, recent stabilization of the ozone induced UV long-term changes being a response to a trendless tendency of total ozone since the mid 1990s. In the case of the slowdown of the total ozone trend over Northern Hemisphere mid-latitudes it seems that clouds will appear as the most important modulator of the UV radiation both in long- and short-time scales over next decades.

Key words. Atmospheric composition and

Pectins, ROS homeostasis and UV-B responses in plant roots.

Science.gov (United States)

Yokawa, Ken; Baluška, František

2015-04-01

Light from the sun contains far-red, visible and ultra violet (UV) wavelength regions. Almost all plant species have been evolved under the light environment. Interestingly, several photoreceptors, expressing both in shoots and roots, process the light information during the plant life cycle. Surprisingly, Arabidopsis root apices express besides the UVR8 UV-B receptor, also root-specific UV-B sensing proteins RUS1 and RUS2 linked to the polar cell-cell transport of auxin. In this mini-review, we focus on reactive oxygen species (ROS) signaling and possible roles of pectins internalized via endocytic vesicle recycling system in the root-specific UV-B perception and ROS homeostasis. Copyright © 2014 Elsevier Ltd. All rights reserved.

UV-induced N2O emission from plants

Science.gov (United States)

Bruhn, Dan; Albert, Kristian R.; Mikkelsen, Teis N.; Ambus, Per

2014-12-01

Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone-depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20-50 nmol m-2h-1, mostly due to the UV component. The emission response to UV-A is of the same magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N2O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed.

Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

Science.gov (United States)

Caputo, Fanny; de Nicola, Milena; Sienkiewicz, Andrzej; Giovanetti, Anna; Bejarano, Ignacio; Licoccia, Silvia; Traversa, Enrico; Ghibelli, Lina

2015-09-01

Efficient inorganic UV shields, mostly based on refracting TiO2 particles, have dramatically changed the sun exposure habits. Unfortunately, health concerns have emerged from the pro-oxidant photocatalytic effect of UV-irradiated TiO2, which mediates toxic effects on cells. Therefore, improvements in cosmetic solar shield technology are a strong priority. CeO2 nanoparticles are not only UV refractors but also potent biological antioxidants due to the surface 3+/4+ valency switch, which confers anti-inflammatory, anti-ageing and therapeutic properties. Herein, UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of CeO2vs. TiO2 nanoparticles on reporter cells. TiO2 irradiated with UV (especially UVA) exerted strong photocatalytic effects, superimposing their pro-oxidant, cell-damaging and mutagenic action when induced by UV, thereby worsening the UV toxicity. On the contrary, irradiated CeO2 nanoparticles, via their Ce3+/Ce4+ redox couple, exerted impressive protection on UV-treated cells, by buffering oxidation, preserving viability and proliferation, reducing DNA damage and accelerating repair; strikingly, they almost eliminated mutagenesis, thus acting as an important tool to prevent skin cancer. Interestingly, CeO2 nanoparticles also protect cells from the damage induced by irradiated TiO2, suggesting that these two particles may also complement their effects in solar lotions. CeO2 nanoparticles, which intrinsically couple UV shielding with biological and genetic protection, appear to be ideal candidates for next-generation sun shields.

On-surface construction of low-dimensional nanostructures with terminal alkynes: Linking strategies and controlling methodologies

Institute of Scientific and Technical Information of China (English)

Jing Liu; Qi-Wei Chen; Kai Wu

2017-01-01

Bottom-up approach to constructing low-dimensional nanostructures on surfaces with terminal alkynes has drawn great interest because of its potential applications in fabricating advanced functional nanomaterials.The diversity of the achieved products manifests rich chemistry of terminal alkynes and hence careful linking strategies and proper controlling methodologies are required for selective preparations of high-quality target nanoarchitectures.This review summarizes various on-surface linking strategies for terminal alkynes,including non-bonding interactions as well as organometallic and covalent bonds,and presents examples to show effective control of surface assemblies and reactions of terminal alkynes by variations of the precursor structures,substrates and activation modes.Systematic studies of the on-surface linkage of terminal alkynes may help efficient and predictable preparations of surface nanomaterials and further understanding of surface chemistry.

UV B-induced vertical migrations of cyanobacteria in a microbial mat

International Nuclear Information System (INIS)

Rebout, B.M.; Garcia-Pichel, F.

1995-01-01

Exposure to moderate doses of UV B (0.35 to 0.79 W m -2 s -1 or 0.98 to 2.2 μmol of photons m -2 s -1 at 310 nm) caused the surface layers of microbial mats from Solar Lake, Sinai, Egypt, to become visibly lighter green. Concurrent with the color change were rapid and dramatic reductions in gross photosynthesis and in the resultant high porewater oxygen concentrations in the surface layers of the mats. The depths at which both maximum gross photosynthesis and maximum oxygen concentrations occurred were displaced downward. In contrast, gross photosynthesis in the deeper layers of the mats increased in response to UV B incident upon the surface. The cessation of exposure to UV B partially reversed all of these changes. Taken together, these responses suggest that photoautotrophic members of the mat community, most likely the dominant cyanobacterium Microcoleus chthonoplastes, were migrating in response to the added UV B. The migration phenomenon was also observed in response to increases in visible radiation and UV A, but UV B was ca. 100-fold more effective than visible radiation and ca. 20-fold more effective than UV A in provoking the response. Migrating microorganisms within this mat are apparently able to sense UV B directly and respond behaviorally to limit their exposure to UV. Because of strong vertical gradients of light and dissolved substances in microbial mats, the migration and the resultant vertical redistribution of photosynthetic activity have important consequences for both the photobiology of the cyanobacteria and the net primary productivity of the mat ecosystem

Potential link between fruit yield, quality parameters and phytohormonal changes in preharvest UV-C treated strawberry.

Science.gov (United States)

Xu, Yanqun; Charles, Marie Thérèse; Luo, Zisheng; Roussel, Dominique; Rolland, Daniel

2017-07-01

Preharvest ultraviolet-C (UV-C) treatment of strawberry is a very new approach, and little information is available on the effect of this treatment on plant growth regulators. In this study, the effect of preharvest UV-C irradiations at three different doses on strawberry yield, fruit quality parameters and endogenous phytohormones was investigated simultaneously. The overall marketable yield of strawberry was not affected by the preharvest UV-C treatments, although more aborted and misshapen fruits were found in UV-C treated groups than in the untreated control. The fruits in the high dose group were firmer and had approximately 20% higher sucrose content and 15% higher ascorbic acid content than the control, while fruits from the middle and low dose groups showed no significant changes in these parameters. The lower abscisic acid (ABA) content found in the fruits in the high UV-C group may be associated with those quality changes. The citric acid content decreased only in the low dose group (reduction of 5.8%), with a concomitant 37% reduction in jasmonic acid (JA) content, compared to the control. The antioxidant status of fruits that received preharvest UV-C treatment was considered enhanced based on their oxygen radical absorbance capacity (ORAC) and malondialdehyde (MDA) content. In terms of aroma, three volatile alcohols differed significantly among the various treatments with obvious activation of alcohol acyltransferase (AAT) activity. The observed synchronous influence on physiological indexes and related phytohormones suggests that preharvest UV-C might affect fruit quality via the action of plant hormones. Crown Copyright © 2017. Published by Elsevier Masson SAS. All rights reserved.

Barium fluoride surface preparation, analysis and UV reflective coatings at Lawrence Livermore National Laboratory

International Nuclear Information System (INIS)

Wuest, C.R.

1992-01-01

Lawrence Livermore National Laboratory (LLNL) has begun a program of study on barium fluoride scintillating crystals for the Barium Fluoride Electromagnetic Calorimeter Collaboration. This program has resulted in a number of significant improvements in the mechanical processing, polishing and coating of barium fluoride crystals. Techniques have been developed using diamond-loaded pitch lapping that can produce 15 angstrom RMS surface finishes over large areas. These lapped surfaces have been shown to be crystalline using Rutherford Back-scattering (RBS). Also, special polishing fixtures have been designed based on mounting technology developed for the 1.1 m diameter optics used in LLNL's Nova Laser. These fixtures allow as many as five 25--50 cm long barium fluoride crystals to be polished and lapped at a time with the necessary tolerances for the 16,000 crystal Barium Fluoride Calorimeter. In addition, results will be presented on coating barium fluoride with UV reflective layers of magnesium fluoride and aluminum

Characterization of ZnO coated polyester fabrics for UV protection

International Nuclear Information System (INIS)

Broasca, G.; Borcia, G.; Dumitrascu, N.; Vrinceanu, N.

2013-01-01

The textile industry aims to develop fabrics adapted to environmental conditions, in particular to UV radiation. Taking into account the demand for such materials, we prepare an inorganic–organic material, based on ZnO microparticles impregnation of polyester textiles, to perform combined UV-protection properties and high hydrophobicity. Scanning electron microscopy, UV reflectance, Impedance Spectroscopy, contact angle, air permeability, resistance to vapor transfer and tensile strength measurement are used for analysis of the surface and volume properties, related to the performance of the material under environmental conditions, as UV radiation, water and water vapors. The impregnation method ensures a good homogeneity and dispersion of ZnO microparticles into the textile polymeric matrix. The optimum level of impregnation of the fabrics is established to 3–5% ZnO, yielding stable properties, without overloading the fabric. The response of the coated polymer indicates better absorbing the UV radiation and dissipating the surface charge, time stability against UV and higher hydrophobic character, without modification of the mechanical properties, offering enhanced performance and comfort under environmental conditions.

UV-SPR biosensor for biomolecular interaction studies

Science.gov (United States)

Geiss, F. A.; Fossati, S.; Khan, I.; Gisbert Quilis, N.; Knoll, W.; Dostalek, J.

2017-05-01

UV surface plasmon resonance (SPR) for direct in situ detection of protein binding events is reported. A crossed relief aluminum grating was employed for diffraction coupling to surface plasmons as an alternative to more commonly used attenuated total reflection method. Wavelength interrogation of SPR was carried out by using transmission measurements in order to probe odorant-binding protein 14 (OBP14) of the honey bee (Apis mellifera). The native oxide layer on the top of an aluminum grating sensor chip allows for covalent coupling of protein molecules by using regular silane-based linkers. The probing of bound OBP14 protein at UV with confined field of surface plasmons holds potential for further studies of interaction with recently developed artificial fluorescent odorants.

Mean Annual UV-B Irradiance

Data.gov (United States)

U.S. Environmental Protection Agency — Ultraviolet-B (UV-B) radiation is the most energetic part of sunlight reaching the Earth's surface (wavelength region is 280 to 315 nm), and it has been shown to...

Characterization of antibodies specific for UV-damaged DNA by ELISA

Energy Technology Data Exchange (ETDEWEB)

Eggset, G; Volden, G; Krokan, H

1987-04-01

The specificity of affinity purified antibodies raised against UV-irradiated DNA was examined using an enzyme-linked immunosorbent assay. DNA irradiated with UV doses higher than needed for saturation with pyrimidine dimers bound increasing amounts of antibody. Photosensitized DNA, containing high amounts of pyrimidine dimers, showed very poor binding of antibody. When UV-irradiated DNA was given a second dose of 340-nm UV light, the binding of antibodies was inhibited. Taken together, this indicates a major specificity for (6-4)-photoproducts, which are photochemically reversed by UV light in the 340-nm region. The antibodies also showed little but detectable binding to pyrimidine glycols produced in DNA by oxidation with OsO/sub 4/. Previously, we have used these antibodies for the detection of UV-induced DNA damage and its repair in human skin in vivo. These findings indicate that (6-4)-photoproducts, considered highly mutagenic, are repaired in human skin.

Characterization of antibodies specific for UV-damaged DNA by ELISA

International Nuclear Information System (INIS)

Eggset, G.; Volden, G.; Krokan, H.; Norsk Hydro Research Centre, Porsgrunn

1987-01-01

The specificity of affinity purified antibodies raised against UV-irradiated DNA was examined using an enzyme-linked immunosorbent assay. DNA irradiated with UV doses higher than needed for saturation with pyrimidine dimers bound increasing amounts of antibody. Photosensitized DNA, containing high amounts of pyrimidine dimers, showed very poor binding of antibody. When UV-irradiated DNA was given a second dose of 340-nm UV light, the binding of antibodies was inhibited. Taken together, this indicates a major specificity for (6-4)-photoproducts, which are photochemically reversed by UV light in the 340-nm region. The antibodies also showed little but detectable binding to pyrimidine glycols produced in DNA by oxidation with OsO 4 . Previously, we have used these antibodies for the detection of UV-induced DNA damage and its repair in human skin in vivo. These findings indicate that (6-4)-photoproducts, considered highly mutagenic, are repaired in human skin. (author)

Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate.

Science.gov (United States)

Yang, Yi; Lu, Xinglin; Jiang, Jin; Ma, Jun; Liu, Guanqi; Cao, Ying; Liu, Weili; Li, Juan; Pang, Suyan; Kong, Xiujuan; Luo, Congwei

2017-07-01

The frequent detection of sulfamethoxazole (SMX) in wastewater and surface waters gives rise of concerns about their ecotoxicological effects and potential risks to induce antibacterial resistant genes. UV/hydrogen peroxide (UV/H 2 O 2 ) and UV/persulfate (UV/PDS) advanced oxidation processes have been demonstrated to be effective for the elimination of SMX, but there is still a need for a deeper understanding of product formations. In this study, we identified and compared the transformation products of SMX in UV, UV/H 2 O 2 and UV/PDS processes. Because of the electrophilic nature of SO 4 - , the second-order rate constant for the reaction of sulfate radical (SO 4 - ) with the anionic form of SMX was higher than that with the neutral form, while hydroxyl radical (OH) exhibited comparable reactivity to both forms. The direct photolysis of SMX predominately occurred through cleavage of the NS bond, rearrangement of the isoxazole ring, and hydroxylation mechanisms. Hydroxylation was the dominant pathway for the reaction of OH with SMX. SO 4 - favored attack on NH 2 group of SMX to generate a nitro derivative and dimeric products. The presence of bicarbonate in UV/H 2 O 2 inhibited the formation of hydroxylated products, but promoted the formation of the nitro derivative and the dimeric products. In UV/PDS, bicarbonate increased the formation of the nitro derivative and the dimeric products, but decreased the formation of the hydroxylated dimeric products. The different effect of bicarbonate on transformation products in UV/H 2 O 2 vs. UV/PDS suggested that carbonate radical (CO 3 - ) oxidized SMX through the electron transfer mechanism similar to SO 4 - but with less oxidation capacity. Additionally, SO 4 - and CO 3 - exhibited higher reactivity to the oxazole ring than the isoxazole ring of SMX. Ecotoxicity of transformation products was estimated by ECOSAR program based on the quantitative structure-activity relationship analysis as well as by experiments using

Building unique surface structure on aramid fibers through a green layer-by-layer self-assembly technique to develop new high performance fibers with greatly improved surface activity, thermal resistance, mechanical properties and UV resistance

Energy Technology Data Exchange (ETDEWEB)

Zhou, Lifang; Yuan, Li; Guan, Qingbao; Gu, Aijuan, E-mail: ajgu@suda.edu.cn; Liang, Guozheng, E-mail: lgzheng@suda.edu.cn

2017-07-31

Highlights: • A green technology is setup to build unique surface structure on aramid fiber (AF). • The method is layer-by-layer self-assembling SiO{sub 2} and layered double hydroxide. • The surface of AF is adjustable by controlling the self-assembly cycle number. • New AF has excellent surface activity, anti-UV, thermal and mechanical properties. • The origin behind attractive performances of new AFs was intensively studied. - Abstract: Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of aramid fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO{sub 2} and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91–95%, about 29–14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and

UV-Enhanced Ethanol Sensing Properties of RF Magnetron-Sputtered ZnO Film.

Science.gov (United States)

Huang, Jinyu; Du, Yu; Wang, Quan; Zhang, Hao; Geng, Youfu; Li, Xuejin; Tian, Xiaoqing

2017-12-26

ZnO film was deposited by the magnetron sputtering method. The thickness of ZnO film is approximately 2 μm. The influence of UV light illumination on C₂H₅OH sensing properties of ZnO film was investigated. Gas sensing results revealed that the UV-illuminated ZnO film displays excellent C₂H₅OH characteristics in terms of high sensitivity, excellent selectivity, rapid response/recovery, and low detection limit down to 0.1 ppm. The excellent sensing performance of the sensor with UV activation could be attributed to the photocatalytic oxidation of ethanol on the surface of the ZnO film, the planar film structure with high utilizing efficiency of UV light, high electron mobility, and a good surface/volume ratio of of ZnO film with a relatively rough and porous surface.

Role of ultraviolet (UV) disinfection in infection control and environmental cleaning.

Science.gov (United States)

Qureshi, Zubair; Yassin, Mohamed H

2013-06-01

Ultraviolet (UV) radiation is capable of disinfecting surfaces, water and air. The UV technology was used for many years. However, safer and more effective delivery systems of UV radiation, make it a very useful option for disinfection. Effective disinfection of environmental surfaces is a key step in the prevention of spread of infectious agents. The traditional manual cleaning is essential in assuring adequate elimination of contamination. However, terminal cleaning is frequently suboptimal or unpredictable in many circumstances. UV-C radiation is an adjunctive disinfectant new technology that could kill a wide array of microorganisms including both vegetative and spore forming pathogens. The technology is getting more affordable and has produced consistent reproducible significant reduction of bacterial contamination.

UV Reflectance of Jupiter's Moon Europa and Asteroid (16) Psyche

Science.gov (United States)

Becker, T. M.; Retherford, K. D.; Roth, L.; Hendrix, A.; McGrath, M. A.; Cunningham, N.; Feaga, L. M.; Saur, J.; Elkins-Tanton, L. T.; Walhund, J. E.; Molyneux, P.

2017-12-01

Surface reflectance observations of solar system objects in the UV are not only complimentary to longer wavelength observations for identifying surface composition, but can also reveal new and meaningful information about the surfaces of those bodies. On Europa, far-UV (FUV) spectral observations made by the Hubble Space Telescope (HST) show that the surface lacks a strong water ice absorption edge near 165 nm, which is intriguing because such a band has been detected on most icy satellites. This may suggest that radiolytic processing by Jupiter's magnetosphere has altered the surface, causing absorption at wavelengths longward of the H2O edge, masking this feature. Additionally, the FUV spectra are blue (increasing albedo with shorter wavelengths), and regions that are observed to be dark in the visible appear bright in the FUV. This spectral inversion, also observed on the Moon and some asteroids, may provide insight into the properties of the surface material and how they are processed.We also explore the UV reflectance spectra of the main belt asteroid (16) Psyche. This asteroid is believed to be the metallic remnant core of a differentiated asteroid, stripped of its mantle through collisions. However, there is speculation that the asteroid could have formed as-is from highly reduced metal-rich material near the Sun early in the formation of the solar system. Further, spectral observations in the infrared have revealed pyroxene and hydroxyl on the asteroid's surface, complicating the interpretation that (16) Psyche is a pure metallic object. Laboratory studies indicate that there are diagnostic spectral features in the UV that could be useful for determining the surface composition. We obtained HST observations of Psyche from 160 - 300 nm. Preliminary results show a featureless, red-sloped spectrum, inconsistent with significant amounts of pyroxene on the surface. We will present the spectra of Europa and the asteroid (16) Psyche and discuss the unique details

UV-induced carbon monoxide emission from living vegetation

DEFF Research Database (Denmark)

Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

2013-01-01

The global burden of carbon monoxide (CO) is rather uncertain. In this paper we address the potential for UV-induced CO emission by living terrestrial vegetation surfaces. Real-time measurements of CO concentrations were made with a cavity enhanced laser spectrometer connected in closed loop...... to either an ecosystem chamber or a plant-leaf scale chamber. Leaves of all examined plant species exhibited emission of CO in response to artificial UV-radiation as well as the UV-component of natural solar radiation. The UV-induced rate of CO emission exhibited a rather low dependence on temperature......, indicating an abiotic process. The emission of CO in response to the UV-component of natural solar radiation was also evident at the ecosystem scale....

Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

KAUST Repository

Caputo, Fanny

2015-08-20

Efficient inorganic UV shields, mostly based on refracting TiO2 particles, have dramatically changed the sun exposure habits. Unfortunately, health concerns have emerged from the pro-oxidant photocatalytic effect of UV-irradiated TiO2, which mediates toxic effects on cells. Therefore, improvements in cosmetic solar shield technology are a strong priority. CeO2 nanoparticles are not only UV refractors but also potent biological antioxidants due to the surface 3+/4+ valency switch, which confers anti-inflammatory, anti-ageing and therapeutic properties. Herein, UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of CeO2vs. TiO2 nanoparticles on reporter cells. TiO2 irradiated with UV (especially UVA) exerted strong photocatalytic effects, superimposing their pro-oxidant, cell-damaging and mutagenic action when induced by UV, thereby worsening the UV toxicity. On the contrary, irradiated CeO2 nanoparticles, via their Ce3+/Ce4+ redox couple, exerted impressive protection on UV-treated cells, by buffering oxidation, preserving viability and proliferation, reducing DNA damage and accelerating repair; strikingly, they almost eliminated mutagenesis, thus acting as an important tool to prevent skin cancer. Interestingly, CeO2 nanoparticles also protect cells from the damage induced by irradiated TiO2, suggesting that these two particles may also complement their effects in solar lotions. CeO2 nanoparticles, which intrinsically couple UV shielding with biological and genetic protection, appear to be ideal candidates for next-generation sun shields. © The Royal Society of Chemistry 2015.

Diurnal variations in the UV albedo of arctic snow

Directory of Open Access Journals (Sweden)

O. Meinander

2008-11-01

Full Text Available The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E, 179 m a.s.l. during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0°C on the following mornings. Hence, the reversible diurnal change, evident for ~1–2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

Synthesis and properties of a novel UV-cured fluorinated siloxane graft copolymer for improved surface, dielectric and tribological properties of epoxy acrylate coating

International Nuclear Information System (INIS)

Yan, Zhenlong; Liu, Weiqu; Gao, Nan; Wang, Honglei; Su, Kui

2013-01-01

A novel functional fluorinated siloxane graft copolymer bearing with vinyl end-groups was synthesized from dihydroxypropyl-terminated poly(dimethylsiloxane) (PDMS), dicarboxyl terminated poly(2,2,3,4,4,4-hexafluorobutyl acrylate) oligomer (CTHFA), 2,4-toluene diissocyanate (TDI) and 2-hydroxyethyl methacrylate (HEMA). The chemical structure was characterized by FT-IR and GPC. The effect of concentration of the vinyl-capped fluorosilicone graft copolymer (Vi-PFSi) on the surface, thermal properties, dielectric and tribological properties of UV-cured films was investigated. Contact angles and surface energies showed that the high hydrophobic and oleophobic surfaces were obtained by incorporation of Vi-PFSi at very low amount (0.5 wt%). X-ray photoelectron spectroscopy (XPS) evidenced that the fluorinated and siloxane moiety selectively migrated to the outermost surface of UV-cured film, thus reduced its surface energy from 45.42 to 15.40 mN/m 2 without affecting its bulk properties. The morphology of fracture surface of modified film exhibited rough fracture surface only at the outermost surface, revealing fluorinated and siloxane groups migrated toward air-side surface. The dielectric constants decreased from 5.32 (1 MHz) for bisphenol-A epoxy methacrylate (EMA) to 2.82 (1 MHz) for modified film when the Vi-PFSi copolymer concentration increased from 0 to 0.8 wt%. Tribological results from abrasion tester suggested that the Vi-PFSi could obviously reduce the abrasion weight loss of modified films.

Laser- and UV-assisted modification of polystyrene surfaces for control of protein adsorption and cell adhesion

International Nuclear Information System (INIS)

Pfleging, Wilhelm; Torge, Maika; Bruns, Michael; Trouillet, Vanessa; Welle, Alexander; Wilson, Sandra

2009-01-01

An appropriate choice of laser and process parameters enables new approaches for the fabrication of polymeric lab-on-chip devices with integrated functionalities. We will present our current research results in laser-assisted modification of polystyrene (PS) with respect to the fabrication of polymer devices for cell culture applications. For this purpose laser micro-patterning of PS and subsequent surface functionalization was investigated as function of laser and process parameters. A high power ArF-excimer laser radiation source with a pulse length of 19 ns as well as a high repetition ArF-excimer laser source with a pulse length of 5 ns were used in order to study the influence of laser pulse length on laser-induced surface oxidation. The change in surface chemistry was characterized by X-ray photoelectron spectroscopy and contact angle measurements. The difference between laser-assisted modification versus UV-lamp assisted modification was investigated. A photolytic activation of specific areas of the polymer surface and subsequent oxidization in oxygen or ambient air leads to a chemically modified polymer surface bearing carboxylic acid groups well-suited for controlled competitive protein adsorption or protein immobilization. Finally, distinct areas for cell growth and adhesion are obtained

Slide-free histology via MUSE: UV surface excitation microscopy for imaging unsectioned tissue (Conference Presentation)

Science.gov (United States)

Levenson, Richard M.; Harmany, Zachary; Demos, Stavros G.; Fereidouni, Farzad

2016-03-01

Widely used methods for preparing and viewing tissue specimens at microscopic resolution have not changed for over a century. They provide high-quality images but can involve time-frames of hours or even weeks, depending on logistics. There is increasing interest in slide-free methods for rapid tissue analysis that can both decrease turn-around times and reduce costs. One new approach is MUSE (microscopy with UV surface excitation), which exploits the shallow penetration of UV light to excite fluorescent signals from only the most superficial tissue elements. The method is non-destructive, and eliminates requirement for conventional histology processing, formalin fixation, paraffin embedding, or thin sectioning. It requires no lasers, confocal, multiphoton or optical coherence tomography optics. MUSE generates diagnostic-quality histological images that can be rendered to resemble conventional hematoxylin- and eosin-stained samples, with enhanced topographical information, from fresh or fixed, but unsectioned tissue, rapidly, with high resolution, simply and inexpensively. We anticipate that there could be widespread adoption in research facilities, hospital-based and stand-alone clinical settings, in local or regional pathology labs, as well as in low-resource environments.

On the link between ExB sheared flows and rational surfaces in fusion plasmas

International Nuclear Information System (INIS)

Hidalgo, C.; Erents, K.; Matthews, G.

2000-11-01

Experimental evidence of flattening in plasma profiles has been observed in the edge region of the JET tokamak. This observation has been interpreted in terms of the influence of rational surfaces on plasma profiles. In the framework of this interpretation, significant ExB sheared flows linked to rational surfaces have been identified. These ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. These results can explain the link between the magnetic topology and the generation of transport barriers reported in fusion devices. (author)

First Derivative UV Spectra of Surface Water as a Monitor of Chlorination in Drinking Water Treatment

Directory of Open Access Journals (Sweden)

V. Zitko

2001-01-01

Full Text Available Many countries require the presence of free chlorine at about 0.1 mg/l in their drinking water supplies. For various reasons, such as cast-iron pipes or long residence times in the distribution system, free chlorine may decrease below detection limits. In such cases it is important to know whether or not the water was chlorinated or if nonchlorinated water entered the system by accident. Changes in UV spectra of natural organic matter in lakewater were used to assess qualitatively the degree of chlorination in the treatment to produce drinking water. The changes were more obvious in the first derivative spectra. In lakewater, the derivative spectra have a maximum at about 280 nm. This maximum shifts to longer wavelengths by up to 10 nm, decreases, and eventually disappears with an increasing dose of chlorine. The water treatment system was monitored by this technique for over 1 year and changes in the UV spectra of water samples were compared with experimental samples treated with known amounts of chlorine. The changes of the UV spectra with the concentration of added chlorine are presented. On several occasions, water, which received very little or no chlorination, may have entered the drinking water system. The results show that first derivative spectra are potentially a tool to determine, in the absence of residual chlorine, whether or not surface water was chlorinated during the treatment to produce potable water.

Defective DNA cross-link removal in Chinese hamster cell mutants hypersensitive to bifunctional alkylating agents

International Nuclear Information System (INIS)

Hoy, C.A.; Thompson, L.H.; Mooney, C.L.; Salazar, E.P.

1985-01-01

DNA repair-deficient mutants from five genetic complementation groups isolated previously from Chinese hamster cells were assayed for survival after exposure to the bifunctional alkylating agents mitomycin C or diepoxybutane. Groups 1, 3, and 5 exhibited 1.6- to 3-fold hypersensitivity compared to the wild-type cells, whereas Groups 2 and 4 exhibited extraordinary hypersensitivity. Mutants from Groups 1 and 2 were exposed to 22 other bifunctional alkylating agents in a rapid assay that compared cytotoxicity of the mutants to the wild-type parental strain, AA8. With all but two of the compounds, the Group 2 mutant (UV4) was 15- to 60-fold more sensitive than AA8 or the Group 1 mutant (UV5). UV4 showed only 6-fold hypersensitivity to quinacrine mustard. Alkaline elution measurements showed that this compound produced few DNA interstrand cross-links but numerous strand breaks. Therefore, the extreme hypersensitivity of mutants from Groups 2 and 4 appeared specific for compounds the main cytotoxic lesions of which were DNA cross-links. Mutant UV5 was only 1- to 4-fold hypersensitive to all the compounds. Although the initial number of cross-links was similar for the three cell lines, the efficiency of removal of cross-links was lowest in UV4 and intermediate in UV5. These results suggest that the different levels of sensitivity are specifically related to different efficiencies of DNA cross-link removal. The phenotype of hypersensitivity to both UV radiation and cross-link damage exhibited by the mutants in Groups 2 and 4 appears to differ from those of the known human DNA repair syndromes

Photodegradation and toxicity changes of antibiotics in UV and UV/H{sub 2}O{sub 2} process

Energy Technology Data Exchange (ETDEWEB)

Fang, Yuan [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Hu Chun, E-mail: huchun@rcees.ac.cn [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Xuexiang, Hu; Dongbin, Wei; Yong, Chen; Jiuhui, Qu [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China)

2011-01-30

The photodegradation of three antibiotics, oxytetracycline (OTC), doxycycline (DTC), and ciprofloxacin (CIP) in UV and UV/H{sub 2}O{sub 2} process was investigated with a low-pressure UV lamp system. Experiments were performed in buffered ultrapure water (UW), local surface water (SW), and treated water from local municipal drinking water treatment plant (DW) and wastewater treatment plant (WW). The efficiency of UV/H{sub 2}O{sub 2} process was affected by water quality. For all of the three selected antibiotics, the fastest degradation was observed in DW, and the slowest degradation occurred in WW. This phenomenon can be explained by R{sub OH,UV}, defined as the experimentally determined {center_dot}OH radical exposure per UV fluence. The R{sub OH,UV} values represent the background {center_dot}OH radical scavenging in water matrix, obtained by the degradation of para-chlorobenzoic acid (pCBA), a probe compound. In natural water, the indirect degradation of CIP did not significantly increase with the addition of H{sub 2}O{sub 2} due to its effective degradation by UV direct photolysis. Moreover, the formation of several photoproducts and oxidation products of antibiotics in UV/H{sub 2}O{sub 2} process was identified using GC-MS. Toxicity assessed by Vibrio fischer (V. fischer), was increased in UV photolysis, for the photoproducts still preserving the characteristic structure of the parent compounds. While in UV/H{sub 2}O{sub 2} process, toxicity increased first, and then decreased; nontoxic products were formed by the oxidation of {center_dot}OH radical. In this process, detoxification was much easier than mineralization for the tested antibiotics, and the optimal time for the degradation of pollutants in UV/H{sub 2}O{sub 2} process would be determined by parent compound degradation and toxicity changes.

UV/PAR radiations and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

Science.gov (United States)

Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

2012-11-01

Water masses from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV and PAR diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Even with relatively low mean daily solar radiation incident on the sea surface (0.12 ± 0.03, 8.46 ± 1.64 and 18.09 ± 4.20 kJ m-2 for UV-B (305 nm), UV-A (380 nm) and PAR, respectively), we report significant light penetration with 10% irradiance depths (Z10% (λ)) reaching 9.5 m for 340 nm (UV-A) radiation in the Eastern sector and 4.5 m in the Mackenzie River influenced area (Western sector). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of UV solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. Extrapolating CDOM to DOC relationships, we estimate that ~ 16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. DOC and CDOM discharges by the Mackenzie River during the MALINA Cruise are estimated as ~ 0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence Excitation/Emission Matrix Spectroscopy (EEMS) and PARAFAC analysis. Our results showed an in-situ biological component (C1) that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta sector, whereas the protein-like (C3) component dominated in the saltiest waters of the North East sector.

The effect of ultraviolet (UV)-B radiation on primary producers

International Nuclear Information System (INIS)

Germ, M.

2003-01-01

Ozone layer in stratosphere is thinning and consequently UV-B radiation on the Earth surface is increasing. Although there is a small portion of UV-B radiation in the solar radiation, it has strong influence on organisms. Targets of UV-B radiation and protective mechanisms in primary producers are described. In the framework of the international project we studied the effect of UV-B radiation on blue-greens, algae, mosses, lichens and vascular plants on the National Institute of Biology

UV Reconstruction Algorithm And Diurnal Cycle Variability

Science.gov (United States)

Curylo, Aleksander; Litynska, Zenobia; Krzyscin, Janusz; Bogdanska, Barbara

2009-03-01

UV reconstruction is a method of estimation of surface UV with the use of available actinometrical and aerological measurements. UV reconstruction is necessary for the study of long-term UV change. A typical series of UV measurements is not longer than 15 years, which is too short for trend estimation. The essential problem in the reconstruction algorithm is the good parameterization of clouds. In our previous algorithm we used an empirical relation between Cloud Modification Factor (CMF) in global radiation and CMF in UV. The CMF is defined as the ratio between measured and modelled irradiances. Clear sky irradiance was calculated with a solar radiative transfer model. In the proposed algorithm, the time variability of global radiation during the diurnal cycle is used as an additional source of information. For elaborating an improved reconstruction algorithm relevant data from Legionowo [52.4 N, 21.0 E, 96 m a.s.l], Poland were collected with the following instruments: NILU-UV multi channel radiometer, Kipp&Zonen pyranometer, radiosonde profiles of ozone, humidity and temperature. The proposed algorithm has been used for reconstruction of UV at four Polish sites: Mikolajki, Kolobrzeg, Warszawa-Bielany and Zakopane since the early 1960s. Krzyscin's reconstruction of total ozone has been used in the calculations.

Substance Flow Analysis and Source Mapping of Chemical UV-filters

International Nuclear Information System (INIS)

Eriksson, E.; Andersen, H. R.; Ledin, A.

2008-01-01

Chemical ultraviolet (UV)-filters are used in sunscreens to protect the skin from harmful UV radiation which may otherwise cause sunburns and skin cancer. Commonly used chemical UV-filters are known to cause endocrine disrupting effects in both aquatic and terrestrial animals as well as in human skin cells. Here, source mapping and substance flow analysis were applied to find the sources of six UV-filters (oxybenzone, avobenzone, 4-methylbenzylidene camphor, octyl methoxycinnamate, octyl dimethyl PABA and homosalate) and to identify the most dominant flows of these substances in Denmark. Urban water, composed of wastewater and surface waters, was found to be the primary recipient of UV-filters, whereby wastewater received an estimated 8.5-65 tonnes and surface waters received 7.1-51 tonnes in 2005. In wastewater treatment plants, their sorption onto sludge is perceived to be an important process and presence in effluents can be expected due to a lack of biodegradability. In addition, the use of UV-filters is expected to continue to increase significantly. Not all filters (e.g., octyl dimethyl PABA and homosalate) are used in Denmark. For example, 4-MBC is mainly associated with self-tanning liquids and private import of sunscreens

Substance Flow Analysis and Source Mapping of Chemical UV-filters

Energy Technology Data Exchange (ETDEWEB)

Eriksson, E., E-mail: eve@env.dtu.dk; Andersen, H. R.; Ledin, A. [Technical University of Denmark, Department of Environmental Engineering (Denmark)

2008-12-15

Chemical ultraviolet (UV)-filters are used in sunscreens to protect the skin from harmful UV radiation which may otherwise cause sunburns and skin cancer. Commonly used chemical UV-filters are known to cause endocrine disrupting effects in both aquatic and terrestrial animals as well as in human skin cells. Here, source mapping and substance flow analysis were applied to find the sources of six UV-filters (oxybenzone, avobenzone, 4-methylbenzylidene camphor, octyl methoxycinnamate, octyl dimethyl PABA and homosalate) and to identify the most dominant flows of these substances in Denmark. Urban water, composed of wastewater and surface waters, was found to be the primary recipient of UV-filters, whereby wastewater received an estimated 8.5-65 tonnes and surface waters received 7.1-51 tonnes in 2005. In wastewater treatment plants, their sorption onto sludge is perceived to be an important process and presence in effluents can be expected due to a lack of biodegradability. In addition, the use of UV-filters is expected to continue to increase significantly. Not all filters (e.g., octyl dimethyl PABA and homosalate) are used in Denmark. For example, 4-MBC is mainly associated with self-tanning liquids and private import of sunscreens.

Influence of fiber surface-treatment on interfacial property of poly(L-lactic acid)/ramie fabric biocomposites under UV-irradiation hydrothermal aging

Energy Technology Data Exchange (ETDEWEB)

Chen Dakai; Li Jing [Institute of Nano- and Bio-polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai 200092 (China); Ren Jie, E-mail: renjie6598@163.com [Institute of Nano- and Bio-polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai 200092 (China) and Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongji University, Shanghai 200092 (China)

2011-04-15

Research highlights: {yields} Ramie fiber is used as reinforced material because it's lowest water absorption among sisal, jute, kenaf and ramie fiber. {yields} Fiber surface-treatment can cause an accelerated decline in mechanical properties of PLLA biocomposites after UV-irradiation hydrothermal aging. {yields} The swelling of ramie fibers reduce the interfacial adhesive strength in critical area of PLLA matrix-ramie fabric interface. - Abstract: The present study is devoted to the effect of fiber surface-treatment on the interfacial property of biocomposites based on poly(L-lactic acid) (PLLA) and ramie fabric. Ramie fiber is used as reinforced material because it's lowest water absorption among sisal, jute, kenaf and ramie fiber. Fiber surface-treatment can increase the water absorption of natural fibers. SEM images show that PLLA biocomposites with treated ramie fabric exhibit better interfacial adhesion character. DMA results show that the storage modulus of PLLA biocomposites with treated ramie increase compared to neat PLLA and PLLA biocomposites with untreated ramie. Unexpectedly, fiber surface-treatment can cause an accelerated decline in mechanical properties of PLLA biocomposites after UV-irradiation hydrothermal aging. Finally, GPC results show that there is no obvious decline in the molecular weight of PLLA. The main reason for this decline is the interfacial destructive effect induced by the water absorption of ramie fiber.

CUVE - Cubesat UV Experiment: Unveil Venus' UV Absorber with Cubesat UV Mapping Spectrometer

Science.gov (United States)

Cottini, V.; Aslam, S.; D'Aversa, E.; Glaze, L.; Gorius, N.; Hewagama, T.; Ignatiev, N.; Piccioni, G.

2017-09-01

Our Venus mission concept Cubesat UV Experiment (CUVE) is one of ten proposals selected for funding by the NASA PSDS3 Program - Planetary Science Deep Space SmallSat Studies. CUVE concept is to insert a CubeSat spacecraft into a Venusian orbit and perform remote sensing of the UV spectral region using a high spectral resolution point spectrometer to resolve UV molecular bands, observe nightglow, and characterize the unidentified main UV absorber. The UV spectrometer is complemented by an imaging UV camera with multiple bands in the UV absorber main band range for contextual imaging. CUVE Science Objectives are: the nature of the "Unknown" UV-absorber; the abundances and distributions of SO2 and SO at and above Venus's cloud tops and their correlation with the UV absorber; the atmospheric dynamics at the cloud tops, structure of upper clouds and wind measurements from cloud-tracking; the nightglow emissions: NO, CO, O2. This mission will therefore be an excellent platform to study Venus' cloud top atmospheric properties where the UV absorption drives the planet's energy balance. CUVE would complement past, current and future Venus missions with conventional spacecraft, and address critical science questions cost effectively.

The genetic architecture of UV floral patterning in sunflower.

Science.gov (United States)

Moyers, Brook T; Owens, Gregory L; Baute, Gregory J; Rieseberg, Loren H

2017-07-01

The patterning of floral ultraviolet (UV) pigmentation varies both intra- and interspecifically in sunflowers and many other plant species, impacts pollinator attraction, and can be critical to reproductive success and crop yields. However, the genetic basis for variation in UV patterning is largely unknown. This study examines the genetic architecture for proportional and absolute size of the UV bullseye in Helianthus argophyllus , a close relative of the domesticated sunflower. A camera modified to capture UV light (320-380 nm) was used to phenotype floral UV patterning in an F 2 mapping population, then quantitative trait loci (QTL) were identified using genotyping-by-sequencing and linkage mapping. The ability of these QTL to predict the UV patterning of natural population individuals was also assessed. Proportional UV pigmentation is additively controlled by six moderate effect QTL that are predictive of this phenotype in natural populations. In contrast, UV bullseye size is controlled by a single large effect QTL that also controls flowerhead size and co-localizes with a major flowering time QTL in Helianthus . The co-localization of the UV bullseye size QTL, flowerhead size QTL and a previously known flowering time QTL may indicate a single highly pleiotropic locus or several closely linked loci, which could inhibit UV bullseye size from responding to selection without change in correlated characters. The genetic architecture of proportional UV pigmentation is relatively simple and different from that of UV bullseye size, and so should be able to respond to natural or artificial selection independently. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

uvsI mutants defective in UV mutagenesis define a fourth epistatic group of uvs genes in Aspergillus.

Science.gov (United States)

Chae, S K; Kafer, E

1993-01-01

Three UV-sensitive mutations of A. nidulans, uvsI, uvsJ and uvsA, were tested for epistatic relationships with members of the previously established groups, here called the "UvsF", "UvsC", and "UvsB" groups. uvsI mutants are defective for spontaneous and induced reversion of certain point mutations and differ also for other properties from previously analyzed uvs types. They are very sensitive to the killing effects of UV-light and 4-NQO (4-nitro-quinoline-N-oxide) but not to MMS (methylmethane sulfonate). When double- and single-mutant uvs strains were compared for sensitivity to these three agents, synergistic or additive effects were found for uvsI with all members of the three groups. The uvsI gene may therefore represent a fourth epistatic group, possibly involved in mutagenic repair. On the other hand, uvsJ was clearly epistatic with members of the UvsF group and fitted well into this group also by phenotype. The uvsA gene was tentatively assigned to the UvsC group. uvsA showed epistatic interactions with uvsC in all tests, and like UvsC-group mutants is UV-sensitive mainly in dividing cells. However, the uvsA mutation does not cause the defects in recombination and UV mutagenesis typical for this group.

Monolayer alignment on azobenzene surfaces during UV light irradiation: Analysis of optical polarized absorption measurement results and theoretical treatment

International Nuclear Information System (INIS)

Zakharov, A.V.; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

2006-01-01

The influence of the charge separation during the trans-cis conformational change on the surface of azobenzene 6Az10PVA monolayer on the polar liquid-crystal monolayer film, such as 4-n-pentyl-4 ' -cyanobiphenyl(5CB), is investigated. The effective anchoring energy (in the Rapini-Papolar form) is phenomenologically described in the framework of the molecular model, which takes into account the interaction between the surface polarization and surface electric field, for number of conformational states of the boundary surface. It is shown, using the experimental data for the voltage across the 6Az10PVA+5CB film, provided by the surface-potential technique, that the charge separation during the conformational changing, caused by the UV irradiation, may lead to changing of the surface alignment of liquid-crystalline molecules. The influence of the photoisomerization process on the orientational order parameter S 2 (t) using the optical polarized absorption measurement is also investigated

Direct UV/Optical Imaging of Stellar Surfaces: The Stellar Imager (SI) Vision Mission

Science.gov (United States)

Carpenter, Kenneth G.; Lyon, Richard G.; Schrijver, Carolus; Karovska, Margarita; Mozurkewich, David

2007-01-01

The Stellar Imager (SI) is a UV/optical, space-based interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and, via asteroseismology, stellar interiors and of the Universe in general. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives, in support of the Living with a Star program in the Exploration Era. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in thc Universe. SI is a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap. We discuss herein the science goals of the SI Mission, a mission architecture that could meet those goals, and the technologies needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

Different atmospheric parameters influence on spectral UV radiation (measurements and modelling)

Energy Technology Data Exchange (ETDEWEB)

Chubarova, N Y [Moscow State Univ. (Russian Federation). Meteorological Observatory; Krotkov, N A [Maryland Univ., MD (United States). JCESS/Meteorology Dept.; Geogdzhaev, I V; Bushnev, S V; Kondranin, T V [SUMGF/MIPT, Dolgoprudny (Russian Federation); Khattatov, V U [Central Aerological Observatory, Dolgoprudny (Russian Federation)

1996-12-31

The ultraviolet (UV) radiation plays a vital role in the biophysical processes despite its small portion in the total solar flux. UV radiation is subject to large variations at the Earth surface depending greatly on solar elevation, ozone and cloud amount, aerosols and surface albedo. The analysis of atmospheric parameters influence is based on the spectral archive data of three spectral instruments: NSF spectroradiometer (Barrow network) (NSF Polar Programs UV Spectroradiometer Network 1991-1992,1992), spectrophotometer (SUVS-M) of Central Aerological Observatory CAO, spectroradiometer of Meteorological Observatory of the Moscow State University (MO MSU) and model simulations based on delta-Eddington approximation

Different atmospheric parameters influence on spectral UV radiation (measurements and modelling)

Energy Technology Data Exchange (ETDEWEB)

Chubarova, N.Y. [Moscow State Univ. (Russian Federation). Meteorological Observatory; Krotkov, N.A. [Maryland Univ., MD (United States). JCESS/Meteorology Dept.; Geogdzhaev, I.V.; Bushnev, S.V.; Kondranin, T.V. [SUMGF/MIPT, Dolgoprudny (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Dolgoprudny (Russian Federation)

1995-12-31

The ultraviolet (UV) radiation plays a vital role in the biophysical processes despite its small portion in the total solar flux. UV radiation is subject to large variations at the Earth surface depending greatly on solar elevation, ozone and cloud amount, aerosols and surface albedo. The analysis of atmospheric parameters influence is based on the spectral archive data of three spectral instruments: NSF spectroradiometer (Barrow network) (NSF Polar Programs UV Spectroradiometer Network 1991-1992,1992), spectrophotometer (SUVS-M) of Central Aerological Observatory CAO, spectroradiometer of Meteorological Observatory of the Moscow State University (MO MSU) and model simulations based on delta-Eddington approximation

Antiradiation UV Vaccine: UV Radiation, Biological effects, lesions and medical management - immune-therapy and immune-protection.

Science.gov (United States)

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

Key Words: Ultraviolet radiation,Standard Erythema Dose(SED), Minimal Erythema Dose(MED), Sun Burns, Solar Dermatitis, Sun Burned Disease, DNA Damage,Cell Damage, Antiradiation UV Vaccine, Immune-Prophylaxis of Sun Burned Diseases, Immune-Prophylaxis of Sun Burns, Immune-Therapy of Sun-Burned Disease and Sun Burns,Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), Toxic Epidermal Necrolysis(TEN). Introduction: High doses of UV generated by solar source and artificial sources create an exposure of mammals and other species which can lead to ultraviolet(UV)radiation- associated disease (including erythema, epilation, keratitis, etc.). UV radiation belongs to the non-ionizing part of the electromagnetic spectrum and ranges between 100 nm and 400 nm with 100 nm having been chosen arbitrarily as the boundary between non-ionizing and ionizing radiation, however EMR is a spectrum and UV can produce molecular ionization. UV radiation is conventionally categorized into 3 areas: UV-A (>315-400 nm),UV-B (>280-315 nm)and UV-C (>100-280 nm) [IARC,Working Group Reports,2005] An important consequence of stratospheric ozone depletion is the increased transmission of solar ultraviolet (UV)radiation to the Earth's lower atmosphere and surface. Stratospheric ozone levels have been falling, in certain areas, for the past several decades, so current surface ultraviolet-B (UV-B) radiation levels are thought to be close to their modern day maximum. [S.Madronich et al.1998] Overexposure of ultraviolet radiation a major cause of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) { collectively referred to as “non-melanoma" skin cancer (NMSC) and melanoma as well, with skin cancers being the most common cancer in North America. [Armstrong et al. 1993, Gallagher et al. 2005] Methods and Experimental Design: Our experiments and testing of a novel UV “Antiradiation Vaccine” have employed a wide variety of laboratory animals which include : Chinchilla

The UVR8 UV-B Photoreceptor: Perception, Signaling and Response

Science.gov (United States)

Tilbrook, Kimberley; Arongaus, Adriana B.; Binkert, Melanie; Heijde, Marc; Yin, Ruohe; Ulm, Roman

2013-01-01

Ultraviolet-B radiation (UV-B) is an intrinsic part of sunlight that is accompanied by significant biological effects. Plants are able to perceive UV-B using the UV-B photoreceptor UVR8 which is linked to a specific molecular signaling pathway and leads to UV-B acclimation. Herein we review the biological process in plants from initial UV-B perception and signal transduction through to the known UV-B responses that promote survival in sunlight. The UVR8 UV-B photoreceptor exists as a homodimer that instantly monomerises upon UV-B absorption via specific intrinsic tryptophans which act as UV-B chromophores. The UVR8 monomer interacts with COP1, an E3 ubiquitin ligase, initiating a molecular signaling pathway that leads to gene expression changes. This signaling output leads to UVR8-dependent responses including UV-B-induced photomorphogenesis and the accumulation of UV-B-absorbing flavonols. Negative feedback regulation of the pathway is provided by the WD40-repeat proteins RUP1 and RUP2, which facilitate UVR8 redimerization, disrupting the UVR8-COP1 interaction. Despite rapid advancements in the field of recent years, further components of UVR8 UV-B signaling are constantly emerging, and the precise interplay of these and the established players UVR8, COP1, RUP1, RUP2 and HY5 needs to be defined. UVR8 UV-B signaling represents our further understanding of how plants are able to sense their light environment and adjust their growth accordingly. PMID:23864838

Effects of UV irradiation on a living skin equivalent

Energy Technology Data Exchange (ETDEWEB)

Nelson, D; Gay, R J [Organogenesis Incorporated, Camton, MA (United States)

1993-05-01

The Living Skin Equivalent is an organotypic coculture composed of human dermal fibroblasts interspersed in a collagen-containing matrix and overlaid with human keratinocytes forming a stratified epidermis. The LSE has a dry, air-exposed epidermal surface suitable for the application of oils, creams and emulsions. The protective effects of an 8% homosylate standard and of five UV-A sunscreens, topically applied to the LSE, were determined and compared with their reported protection factors in human skin. Morphological changes and the release of proinflammatory mediators (interleukin-1-''alpha, tumor necrosis factor-[alpha] and prostaglandin E2) implicated in UV-induced erythema were also demonstrated in the LSE exposed to UV-A or UV-B. The data suggest that the LSE can be used for studying the effects of UV radiation on skin and may have utility for assessing the efficacy of certain sunscreens against UV-B and UV-A. (Author).

Effects of UV irradiation on a living skin equivalent

International Nuclear Information System (INIS)

Nelson, D.; Gay, R.J.

1993-01-01

The Living Skin Equivalent is an organotypic coculture composed of human dermal fibroblasts interspersed in a collagen-containing matrix and overlaid with human keratinocytes forming a stratified epidermis. The LSE has a dry, air-exposed epidermal surface suitable for the application of oils, creams and emulsions. The protective effects of an 8% homosylate standard and of five UV-A sunscreens, topically applied to the LSE, were determined and compared with their reported protection factors in human skin. Morphological changes and the release of proinflammatory mediators (interleukin-1-''alpha, tumor necrosis factor-α and prostaglandin E2) implicated in UV-induced erythema were also demonstrated in the LSE exposed to UV-A or UV-B. The data suggest that the LSE can be used for studying the effects of UV radiation on skin and may have utility for assessing the efficacy of certain sunscreens against UV-B and UV-A. (Author)

Durable diamond-like carbon templates for UV nanoimprint lithography

International Nuclear Information System (INIS)

Tao, L; Ramachandran, S; Nelson, C T; Overzet, L J; Goeckner, M; Lee, G; Hu, W; Lin, M; Willson, C G; Wu, W

2008-01-01

The interaction between resist and template during the separation process after nanoimprint lithography (NIL) can cause the formation of defects and damage to the templates and resist patterns. To alleviate these problems, fluorinated self-assembled monolayers (F-SAMs, i.e. tridecafluoro-1,1,2,2,tetrahydrooctyl trichlorosilane or FDTS) have been employed as template release coatings. However, we find that the FDTS coating undergoes irreversible degradation after only 10 cycles of UV nanoimprint processes with SU-8 resist. The degradation includes a 28% reduction in surface F atoms and significant increases in the surface roughness. In this paper, diamond-like carbon (DLC) films were investigated as an alternative material not only for coating but also for direct fabrication of nanoimprint templates. DLC films deposited on quartz templates in a plasma enhanced chemical vapor deposition system are shown to have better chemical and physical stability than FDTS. After the same 10 cycles of UV nanoimprints, the surface composition as well as the roughness of DLC films were found to be unchanged. The adhesion energy between the DLC surface and SU-8 is found to be smaller than that of FDTS despite the slightly higher total surface energy of DLC. DLC templates with 40 nm features were fabricated using e-beam lithography followed by Cr lift-off and reactive ion etching. UV nanoimprinting using the directly patterned DLC templates in SU-8 resist demonstrates good pattern transfer fidelity and easy template-resist separation. These results indicate that DLC is a promising material for fabricating durable templates for UV nanoimprint lithography

UV/visible albedos from airborne measurements

Science.gov (United States)

Webb, A.; Kylling, A.; Stromberg, I.

2003-04-01

During the INSPECTRO campaign effective surface albedo was measured at UV and visible wavelengths from two airborne platforms, a Cessna light aircraft and a hot air balloon. On board the Cessna was a scanning spectroradiometer measuring from 300 - 500nm at 10nm intervals. The NILU cube, with 6 faces and two UV channels at 312 and 340nm, was suspended beneath the hot air balloon. Flights took place over East Anglia during September, 2002. Balloon flights were made below cloud layers, while the Cessna flew both above and below cloud. The Cessna also flew over Barton Bendish, where surface albedos have been measured for ground truthing of satellite data, and measured the effective albedo at four visible wave- lengths in the centres of the satellite bandpass functions. Results of measurements from the different platforms are compared, and model simulations used to deduce the surface albedo from the effective albedo at altitude, giving, for example, an albedo of 0.02 ± 0.01 at 340nm.

How do environmental and behavioral factors impact ultraviolet radiation effects on health: the RISC-UV Project

Science.gov (United States)

Correa, M. P.; Godin-Beekmann, S.; Haeffelin, M.; Saiag, P.; Mahe, E.; Brogniez, C.; Dupont, J. C.; Pazmiño, A.; Auriol, F.; Bonnel, B.

2009-04-01

Introduction: RISC-UV is a research project on "Impact of climate change on ultraviolet radiation and risks for health", a research project in which physicists, meteorologists and physicians work together to assess the relative role played by environmental and behavioral factors in the UV-related diseases as skin cancer and vitamin D deficiency. Environmental factors are related to the role played by the alteration in intensity of UV radiation at the Earth's surface resulting from variation in several factors affected by climate change and human activities: stratospheric ozone, cloud cover, aerosols and the reflectivity of the surface. On the other hand, behavioral factors are related to the sun over/underexposure and the correct use of sun-protection (hats, caps, sunglasses, sunscreen lotion, etc.). RISC-UV is organized around three main areas: 1) Organization of a workshop, scheduled for January 2009, which aims to describe the state of the art in the subject within each community and define the requirements of pathologists for epidemiological studies; 2) A pilot study intended to evaluate the consistency between UV measurements delivered simultaneously by satellite-based instruments, ground instruments, radiometers and individual dosimeters. This study is based on measurements campaigns and an analysis of the long-term consistency of data series relating to UV radiation and associated parameters; and 3) Analysis of the weights of medical, behavioral and environmental parameters involved in skin carcinogenesis. A detailed description of these areas can be found in http://www.gisclimat.fr/Doc/GB/D_projects/RISC-UV_GB.html. This presentation focuses on the first results of the UV experimental measurements performed between September 8th and October 8th 2008 in Palaiseau, France (48.7˚ N; 2.2˚ E; 170m - Haeffelin et al., 2005). A second campaign is foreseen for the spring of 2009. The purpose of these campaigns is to obtain, analyze and quantitatively link the

Solar UV irradiation-induced production of N2O from plant surfaces - low emissions rates but all over the world.

Science.gov (United States)

Mikkelsen, T. N.; Bruhn, D.; Ambus, P.

2016-12-01

Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20-50 nmol m-2 h-1, mostly due to the UV component. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed.

Climate Variability, Dissolved Organic Carbon, UV Exposure, and Amphibian Decline

Science.gov (United States)

Brooks, P. D.; O'Reilly, C. M.; Diamond, S.; Corn, S.; Muths, E.; Tonnessen, K.; Campbell, D. H.

2001-12-01

Increasing levels of UV radiation represent a potential threat to aquatic organisms in a wide range of environments, yet controls on in situ variability on UV exposure are relatively unknown. The primary control on the penetration of UV radiation in surface water environments is the amount of photoreactive dissolved organic carbon (DOC). Consequently, biogeochemical processes that control the cycling of DOC also affect the exposure of aquatic organisms to UV radiation. Three years of monitoring UV extinction and DOC composition in Rocky Mountain, Glacier, Sequoia/ Kings Canyon, and Olympic National Parks demonstrate that the amount of fulvic acid DOC is much more important than the total DOC pool in controlling UV attenuation. This photoreactive component of DOC originates primarily in soil, and is subject both to biogeochemical controls (e.g. temperature, moisture, vegetation, soil type) on production, and hydrologic controls on transport to surface water and consequently UV exposure to aquatic organisms. Both of these controls are positively related to precipitation with greater production and transport associated with higher precipitation amounts. For example, an approximately 20 percent reduction in precipitation from 1999 to 2000 resulted in a 27% - 59% reduction in the amount of photoreactive DOC at three sites in Rocky Mountain National Park. These differences in the amount of hydrophobic DOC result in an increase in UV exposure in the aquatic environment by a factor of 2 or more. Implications of these findings for observed patterns of amphibian decline will be discussed.

Development of a low cost UV index datalogger and comparison between UV index sensors

Science.gov (United States)

Gomes, L. M.; Ventura, L.

2018-02-01

Ultraviolet radiation (UVR) is the part of radiation emitted by the Sun, with range between 280 nm and 400 nm, and that reaches the Earth's surface. The UV rays are essential to the human because it stimulates the production of vitamin D but this radiation may be related to several health problems, including skin cancer and ocular diseases like pterygium, photokeratitis, cataract and more. To inform people about UV radiation, it is adopted the Ultraviolet Index (UVI). This UVI consists in a measure of solar UV radiation level, which contributes to cause sunburn on skin, also known as Erythema, and is indicated as an integer number between 1 and 14, associated to categories from low to extreme respectively. The aim of this work was to develop a low cost UVI datalogger capable of measuring three different UVI sensors simultaneously, record their data with timestamp and serve the measures online through a dedicated server, so general public can access their data and see the current UV radiation conditions. We also compared three different UVI sensors (SGlux UV cosine, Skye SKU440 and SiLabs SI1145) between them and with meteorological models during a period of months to verify their compliance. With five months data, we could verify the sensors working characteristics and decide which among them are the most suitable for research purposes.

N-linked glycans are required on epithelial Na+ channel subunits for maturation and surface expression.

Science.gov (United States)

Kashlan, Ossama B; Kinlough, Carol L; Myerburg, Michael M; Shi, Shujie; Chen, Jingxin; Blobner, Brandon M; Buck, Teresa M; Brodsky, Jeffrey L; Hughey, Rebecca P; Kleyman, Thomas R

2018-03-01

Epithelial Na + channel (ENaC) subunits undergo N-linked glycosylation in the endoplasmic reticulum where they assemble into an αβγ complex. Six, 13, and 5 consensus sites (Asn-X-Ser/Thr) for N-glycosylation reside in the extracellular domains of the mouse α-, β-, and γ-subunits, respectively. Because the importance of ENaC N-linked glycans has not been fully addressed, we examined the effect of preventing N-glycosylation of specific subunits on channel function, expression, maturation, and folding. Heterologous expression in Xenopus oocytes or Fischer rat thyroid cells with αβγ-ENaC lacking N-linked glycans on a single subunit reduced ENaC activity as well as the inhibitory response to extracellular Na + . The lack of N-linked glycans on the β-subunit also precluded channel activation by trypsin. However, channel activation by shear stress was N-linked glycan independent, regardless of which subunit was modified. We also discovered that the lack of N-linked glycans on any one subunit reduced the total and surface levels of cognate subunits. The lack of N-linked glycans on the β-subunit had the largest effect on total levels, with the lack of N-linked glycans on the γ- and α-subunits having intermediate and modest effects, respectively. Finally, channels with wild-type β-subunits were more sensitive to limited trypsin proteolysis than channels lacking N-linked glycans on the β-subunit. Our results indicate that N-linked glycans on each subunit are required for proper folding, maturation, surface expression, and function of the channel.

Comparison of UV-C and Pulsed UV Light Treatments for Reduction of Salmonella, Listeria monocytogenes, and Enterohemorrhagic Escherichia coli on Eggs.

Science.gov (United States)

Holck, Askild L; Liland, Kristian H; Drømtorp, Signe M; Carlehög, Mats; McLEOD, Anette

2018-01-01

Ten percent of all strong-evidence foodborne outbreaks in the European Union are caused by Salmonella related to eggs and egg products. UV light may be used to decontaminate egg surfaces and reduce the risk of human salmonellosis infections. The efficiency of continuous UV-C (254 nm) and pulsed UV light for reducing the viability of Salmonella Enteritidis, Listeria monocytogenes, and enterohemorrhagic Escherichia coli on eggs was thoroughly compared. Bacterial cells were exposed to UV-C light at fluences from 0.05 to 3.0 J/cm 2 (10 mW/cm 2 , for 5 to 300 s) and pulsed UV light at fluences from 1.25 to 18.0 J/cm 2 , resulting in reductions ranging from 1.6 to 3.8 log, depending on conditions used. Using UV-C light, it was possible to achieve higher reductions at lower fluences compared with pulsed UV light. When Salmonella was stacked on a small area or shielded in feces, the pulsed UV light seemed to have a higher penetration capacity and gave higher bacterial reductions. Microscopy imaging and attempts to contaminate the interior of the eggs with Salmonella through the eggshell demonstrated that the integrity of the eggshell was maintained after UV light treatments. Only minor sensory changes were reported by panelists when the highest UV doses were used. UV-C and pulsed UV light treatments appear to be useful decontamination technologies that can be implemented in continuous processing.

Differential causes of mutation and killing in Escherichia coli after psoralen plus light treatment: monoadducts and cross-links

Energy Technology Data Exchange (ETDEWEB)

Seki, T; Nozu, K [Nara Medical Univ., Kashihara (Japan); Kondo, S

1978-01-01

On treatment with 8-methoxypsoralen plus near uv light, an excision (uvrB/sup -/) strain of Escherichia coli showed about 3- and 10 times higher sensitivities to killing and mutation, respectively, than its parental strain. On re-irradiation with near uv in the absence of unbound psoralen, the uvrB/sup -/ strain pretreated with psoralen plus near uv showed a decrease in both survival and mutation. After treatment with psoralen plus near uv, re-irradiation of T7DNA in the absence of unbound psoralen caused an increase in the cross-linked fraction with an equivalent decrease in the non-cross-linked fraction. From these and previous results, it is concluded that monoadducts produced by treatment with psoralen plus near uv are converted to cross-links by further irradiation and that, in E.coli, monoadducts are responsible for the mutation induced by psoralen-plus-light whereas cross-links are the major cause of its lethal action.

Response surface methodology as a tool for modeling and optimization of Bacillus subtilis spores inactivation by UV/ nano-Fe0 process for safe water production.

Science.gov (United States)

Yousefzadeh, Samira; Matin, Atiyeh Rajabi; Ahmadi, Ehsan; Sabeti, Zahra; Alimohammadi, Mahmood; Aslani, Hassan; Nabizadeh, Ramin

2018-04-01

One of the most important aspects of environmental issues is the demand for clean and safe water. Meanwhile, disinfection process is one of the most important steps in safe water production. The present study aims at estimating the performance of UV, nano Zero-Valent Iron particles (nZVI, nano-Fe 0 ), and UV treatment with the addition of nZVI (combined process) for Bacillus subtilis spores inactivation. Effects of different factors on inactivation including contact time, initial nZVI concentration, UV irradiance and various aerations conditions were investigated. Response surface methodology, based on a five-level, two variable central composite design, was used to optimize target microorganism reduction and the experimental parameters. The results indicated that the disinfection time had the greatest positive impact on disinfection ability among the different selected independent variables. According to the results, it can be concluded that microbial reduction by UV alone was more effective than nZVI while the combined UV/nZVI process demonstrated the maximum log reduction. The optimum reduction of about 4 logs was observed at 491 mg/L of nZVI and 60 min of contact time when spores were exposed to UV radiation under deaerated condition. Therefore, UV/nZVI process can be suggested as a reliable method for Bacillus subtilis spores inactivation. Copyright © 2018. Published by Elsevier Ltd.

UV-assisted synthesis of surface modified mesoporous TiO{sub 2}/G microspheres and its electrochemical performances in lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Tong, Xiaoling; Zeng, Min, E-mail: zengmin@swust.edu.cn; Li, Jing; Li, Fuyun

2017-01-15

Highlights: • We synthesize the surface modified mesoporous TiO{sub 2}/G microspheres, which possess high surface area with 258 m{sup 2} g{sup −1} and narrow pore size at about 7.8 nm. • The surface reaction mechanism of the UV-assisted synthesis mesoporous TiO{sub 2}/G microspheres has been explored. • The as-made TiO{sub 2}/G microspheres exhibit excellent electrochemical performances and deliver a capacity of 141 mAh g{sup −1} upon 100 cycles even at 1 C. - Abstract: Three-dimensional mesoporous TiO{sub 2}/graphene (TiO{sub 2}/G) microspheres have been successfully synthesized through a simple UV-assisted method of reduced graphene oxide with hydrazine. The as-made surface modified mesoporous TiO{sub 2}/G microspheres possess large surface area and exhibit a high initial discharge capacity of 220 mAh g{sup −1} and retain 84% (∼185 mAh g{sup −1}) of reversible capacity over 100 cycles at a rate of 0.2C. In addition, TiO{sub 2}/G microspheres display improved cyclic performance, excellent rate capability and enhanced electrical conductivity, which are superior to the bare TiO{sub 2} microspheres. Furthermore, TiO{sub 2}/G microspheres can achieve a reversible capacity of 141 mAh g{sup −1} upon 100 cycles even at the 1C rate. We believe that the mesoporous TiO{sub 2}/G microspheres are expected to be a promising high performance anode material for the next generation lithium ion batteries.

Environmental occurrence and distribution of organic UV stabilizers and UV filters in the sediment of Chinese Bohai and Yellow Seas.

Science.gov (United States)

Apel, Christina; Tang, Jianhui; Ebinghaus, Ralf

2018-04-01

Organic UV stabilizers and UV filters are applied to industrial materials and cosmetics worldwide. In plastics they prevent photo-induced degradation, while in cosmetics they protect human skin against harmful effects of UV radiation. This study reports on the occurrence and distribution of organic UV stabilizers and UV filters in the surface sediment of the Chinese Bohai and Yellow Seas for the first time. In total, 16 out of 21 analyzed substances were positively detected. Concentrations ranged from sub-ng/g dw to low ng/g dw. The highest concentration of 25 ng/g dw was found for octocrylene (OC) in the Laizhou Bay. In the study area, characteristic composition profiles could be identified. In Korea Bay, the dominating substances were OC and ethylhexyl salicylate (EHS). All other analytes were below their method quantification limit (MQL). Around the Shandong Peninsula, highest concentrations of benzotriazole derivatives were observed in this study with octrizole (UV-329) as the predominant compound, reaching concentrations of 6.09 ng/g dw. The distribution pattern of UV-329 and bumetrizole (UV-326) were related (Pearson correlation coefficient r > 0.98, p « 0.01 around the Shandong Peninsula), indicating an identical input pathway and similar environmental behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation and removal of genotoxic activity during UV/H

NARCIS (Netherlands)

Heringa, M.B.; Harmsen, D.J.H.; Beerendonk, E.F.; Reus, A.A.; Krul, C.A.M.; Metz, D.H.; Ijpelaar, G.F.

2011-01-01

The objective of this study was to determine the genotoxic activity of water after UV/H₂O₂ oxidation and GAC filtration. Pre-treated surface water from three locations was treated with UV/H₂O₂ with medium pressure (MP) lamps and passed through granulated

The combined action of UV irradiation and chemical treatment on the titanium surface of dental implants

Energy Technology Data Exchange (ETDEWEB)

Spriano, Silvia [Politecnico di Torino, Department of Applied Science and Technology, Corso Duca degli Abruzzi, 24-10129 Torino (Italy); Ferraris, Sara, E-mail: sara.ferraris@polito.it [Politecnico di Torino, Department of Applied Science and Technology, Corso Duca degli Abruzzi, 24-10129 Torino (Italy); Bollati, Daniele; Morra, Marco; Cassinelli, Clara [Nobil Bio Ricerche, Portacomaro (Italy); Lorenzon, Giorgio [Centro Chirurgico, Via Mallonetto, 47, 10032, Brandizzo Torino (Italy)

2015-09-15

Highlights: • A combined UV irradiation and H{sub 2}O{sub 2} treatment was applied to titanium surfaces. • A thin, homogeneous, not porous, crack-free and bioactive oxide layer was obtained. • The process significantly improves the biological response of titanium surfaces. • A clinical case demonstrates the effectiveness of the proposed treatment. - Abstract: The purpose of this paper is to describe an innovative treatment for titanium dental implants, aimed at faster and more effective osteointegration. The treatment has been performed with the use of hydrogen peroxide, whose action was enhanced by concomitant exposure to a source of ultraviolet light. The developed surface oxide layer was characterized from the physical and chemical points of view. Moreover osteoblast-like SaOS2 cells were cultured on treated and control titanium surfaces and cell behavior investigated by scanning electron microscope observation and gene expression measurements. The described process produces, in only 6 min, a thin, homogeneous, not porous, free of cracks and bioactive (in vitro apatite precipitation) oxide layer. High cell density, peculiar morphology and overexpression of several genes involved with osteogenesis have been observed on modified surfaces. The proposed process significantly improves the biological response of titanium surfaces, and is an interesting solution for the improvement of bone integration of dental implants. A clinical application of the described surfaces, with a 5 years follow-up, is reported in the paper, as an example of the effectiveness of the proposed treatment.

Cross-Linked ZnO Nanowalls Immobilized onto Bamboo Surface and Their Use as Recyclable Photocatalysts

Directory of Open Access Journals (Sweden)

Chunde Jin

2014-01-01

Full Text Available A novel recyclable photocatalyst was fabricated by hydrothermal method to immobilize the cross-linked ZnO nanowalls on the bamboo surface. The resultant samples were characterized by using scanning electron microscopy (SEM, X-ray diffraction (XRD, energy dispersive spectroscopy (EDS, and Fourier transformation infrared (FTIR techniques. FTIR spectra demonstrated that the cross-linked wurtzite ZnO nanowalls and bamboo surface were interconnected with each other by hydrogen bonds. Meanwhile, the cross-linked ZnO nanowalls modified bamboo (CZNB presented a superior photocatalytic ability and could be recycled at least 3 times with a photocatalytic efficiency up to 70%. The current research provides a new opportunity for the development of a portable and recycled biomass-based photocatalysts which can be an efficiently degraded pollutant solution and reused several times.

Impact of UV Radiation on Genome Stability and Human Health.

Science.gov (United States)

Roy, Sujit

2017-01-01

Gradual depletion of the atmospheric ozone layer during the past few years has increased the incidence of solar UV radiation specifically the UV-C on earth's surface is one of the major environmental concerns because of the harmful effects of this radiation in all forms of life. The solar UV radiation including the harmful wavelength range of UV-B (280-320 nm) represents a significant climatic stress for both animals and plants, causing damage to the fundamental biomolecules such as DNA, proteins and lipids, thus activating genotoxic stress and induces genome instability. When DNA absorbs UV-B light, energy from the photon causes covalent linkages to form between adjacent pyrimidine bases, creating photoproducts, primarily cyclobutane pyrimidine dimers (CPDs) and pyrimidine-6,4-pyrimidinone photoproduct (6,4PPs). Pyrimidine dimers create distortions in the DNA strands and therefore can inhibit DNA replication as well transcription. Lack of efficient repair of UV-induced DNA damage may induce the formation of DNA double stand breaks (DSBs), one of the serious forms of damage in DNA double helix, as well as oxidative damage. Unrepaired DSBs in the actively dividing somatic cells severely affect cell growth and development, finally results in loss of cell viability and development of various diseases, such as cancer in man.This chapter mainly highlights the incidence of solar UV-radiation on earth's surface along with the formation of major types of UV-induced DNA damage and the associated repair mechanisms as well as methods of detecting DNA damage and finally our present understanding on the impact on solar UV radiation on human health.

UV Ink-Jet printability and durability of stone and foil

Directory of Open Access Journals (Sweden)

Tadeja Muck

2014-07-01

Full Text Available he use of ultraviolet (UV printing technology has impacted printing industry in last years due to its applicability on many different »absorptive« as well as »non-absorptive« printing materials. The printability of building materials and recycled foils is relatively unknown. For primary building materials like stones, functionality can be explored with the use of UV printing technology; increased visual, informative effect or even “creative printing” of buildings. Also several aspects of recycled foils reusability as a printing material could be find (printed packaging material or also like secondary building materials. In the present study, printability of the stone and recycled foil and durability of UV prints was explored by means of macroscopically and microscopically characterization. Results indicate that higher print quality can be achieved on polished stone and on coated foil, which surfaces have higher smoothness. Durability of UV prints at freezing is higher at unpolished stone and coated foil that is at materials with the higher surface energy.

Coumarin-BODIPY hybrids by heteroatom linkage: versatile, tunable and photostable dye lasers for UV irradiation.

Science.gov (United States)

Esnal, I; Duran-Sampedro, G; Agarrabeitia, A R; Bañuelos, J; García-Moreno, I; Macías, M A; Peña-Cabrera, E; López-Arbeloa, I; de la Moya, S; Ortiz, M J

2015-03-28

Linking amino and hydroxycoumarins to BODIPYs through the amino or hydroxyl group lets the easy construction of unprecedented photostable coumarin-BODIPY hybrids with broadened and enhanced absorption in the UV spectral region, and outstanding wavelength-tunable laser action within the green-to-red spectral region (∼520-680 nm). These laser dyes allow the generation of a valuable tunable UV (∼260-350 nm) laser source by frequency doubling, which is essential to study accurately the photochemistry of biological molecules under solar irradiation. The tunability is achieved by selecting the substitution pattern of the hybrid. Key factors are the linking heteroatom (nitrogen vs. oxygen), the number of coumarin units joined to the BODIPY framework and the involved linking positions.

Arctic sea-ice melting: Effects on hydroclimatic variability and on UV-induced carbon cycling

Science.gov (United States)

Sulzberger, Barbara

2016-04-01

Since 1980 both the perennial and the multiyear central Arctic sea ice areas have declined by approximately 13 and 15% per decade, respectively (IPCC, 2013). Arctic sea-ice melting has led to an increase in the amplitude of the Northern Hemisphere jet stream and, as a consequence, in more slowly moving Rossby waves which results in blocking of weather patterns such as heat waves, droughts, cold spells, and heavy precipitation events (Francis and Vavrus, 2012). Changing Rossby waves account for more than 30% of the precipitation variability over several regions of the northern middle and high latitudes, including the US northern Great Plains and parts of Canada, Europe, and Russia (Schubert et al., 2011). From 2007 to 2013, northern Europe experienced heavy summer precipitation events that were unprecedented in over a century, concomitant with Arctic sea ice loss (Screen, 2013). Heavy precipitation events tend to increase the runoff intensity of terrigenous dissolved organic matter (tDOM) (Haaland et al., 2010). In surface waters tDOM is subject to UV-induced oxidation to produce atmospheric CO2. Mineralization of DOM also occurs via microbial respiration. However, not all chemical forms of DOM are available to bacterioplankton. UV-induced transformations generally increase the bioavailability of tDOM (Sulzberger and Durisch-Kaiser, 2009). Mineralization of tDOM is an important source of atmospheric CO2 and this process is likely to contribute to positive feedbacks on global warming (Erickson et al., 2015). However, the magnitudes of these potential feedbacks remain unexplored. This paper will discuss the following items: 1.) Links between Arctic sea-ice melting, heavy precipitation events, and enhanced tDOM runoff. 2.) UV-induced increase in the bioavailability of tDOM. 3.) UV-mediated feedbacks on global warming. References Erickson, D. J. III, B. Sulzberger, R. G. Zepp, A. T. Austin (2015), Effects of stratospheric ozone depletion, solar UV radiation, and climate

Ultraviolet (UV) disinfection of grey water: particle size effects.

Science.gov (United States)

Winward, G P; Avery, L M; Stephenson, T; Jefferson, B

2008-02-01

The impact of water quality on the ultraviolet (UV) disinfection of grey water was investigated with reference to urban water reuse. Direct UV disinfection of grey water did not meet the stringent California State Title 22 criteria for unrestricted urban water reuse due to the presence of particulate material ranging from or = 2000 microm in size. Grey water was manipulated by settling to produce fractions of varying particle size distributions and blending was employed post-disinfection to extract particle-associated coliforms (PACs). The efficacy of UV disinfection was found to be linked to the particle size of the grey water fractions. The larger particle size fractions with a mean particle size of 262 microm and above were observed to shield more coliforms from UV light than did the smaller particles with a mean particle size below 119 microm. Up to 70% of total coliforms in the larger particle size fractions were particle-associated following a UV dose (fluence) of 260 mJ.cm(-2) and would remain undetected by standard coliform enumeration techniques. Implications for urban water reuse are discussed and recommendations made for grey water treatment to ensure removal of particle-associated indicator bacteria and pathogens prior to UV disinfection.

Effects of He{sup +} ion implantation on surface properties of UV-cured Bis-GMA/TEGDMA bio-compatible resins

Energy Technology Data Exchange (ETDEWEB)

Fuentes, G.G., E-mail: gfuentes@ain.e [Center of Advanced Surface Engineering, AIN, Cordovilla-Pamplona, E-31191 (Spain); Esparza, J.; Rodriguez, R.J. [Center of Advanced Surface Engineering, AIN, Cordovilla-Pamplona, E-31191 (Spain); Manso-Silvan, M. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, E-28049 (Spain); Palomares, J. [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, E-28049 (Spain); Juhasz, J.; Best, S. [Cambridge Centre for Medical Materials, Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Str, Cambridge CB2 3QZ (United Kingdom); Mattilla, R.; Vallittu, P. [Institute of Dentistry, Turku Clinical Biomaterials Centre, Itaeinen Pitkaekatu 4, B FI-20520, Turku (Finland); Achanta, S. [Falex Tribology Wingepark 23 B, 3110 Rotselaar (Belgium); Giazzon, M.; Weder, G. [Centre Suisse d' Electronique et de Microtechnique, CSEM, Jaquet-Drot 1, CH-2002 Neuchatel (Switzerland); Donati, I. [Department of Life Sciences, University of Trieste, Via Licio Giorgieri 1, I 34127 Trieste (Italy)

2011-01-15

This work reports on the surface characterisation of 2,2-bis[4-(2-hydroxy-3-methacryloxyl-oxypropoxy)phenyl]propane/triethylene glycol dimethacrylate bio-compatible resins after high energy He{sup +} ion implantation treatments. The samples have been characterised by diffuse reflectance FT-IR, X-ray photo-electron spectroscopy, ultramicro-hardness and nano-scratch wear tests. In addition, osteblast cell assays MG-63 have been used to test the bio-compatibility of the resin surfaces after the ion implantation treatments. It has been observed that the maximum surface hardening of the resin surfaces is achieved at He-ion implantation energies of around 50 keV and fluences of 1 x 10{sup 16} cm{sup -2}. At 50 keV of He-ion bombardment, the wear rate of the resin surface decreases by a factor 2 with respect to the pristine resin. Finally, in vitro tests indicate that the He-ion implantation does not affect to the cell-proliferation behaviour of the UV-cured resins. The enhancement of the surface mechanical properties of these materials can have beneficial consequences, for instance in preventing wear and surface fatigue of bone-fixation prostheses, whose surfaces are continuously held to sliding and shearing contacts of sub-millimetre scale lengths.

UV Deprivation Influences Social UV Preference in Juvenile Sticklebacks

Directory of Open Access Journals (Sweden)

Ricarda Modarressie

2015-05-01

Full Text Available Social aggregations occur in many different animal taxa and mainly result from non-random assortment. Investigating factors that shape and maintain the composition of social aggregations are among others a main topic for understanding ecological speciation processes. Aggregation decisions are mediated by olfactory and visual cues, which in many animals are extended into the UV part of the electromagnetic spectrum. Here, we were interested in developmental plasticity of social preferences with respect to UV radiation in aquatic organisms. Specifically, we tested whether different lighting environments with respect to UV wavelengths during early life stages influence the shoaling preference in juvenile threespine sticklebacks (Gasterosteus aculeatus. Family (full-sibling groups were split and reared under UV-lacking (UV- and UV-present (UV+ lighting conditions. Subsequent shoal choice experiments, in which test fish from both rearing conditions could simultaneously choose between a shoal seen behind a UV-blocking (UV- and a shoal seen behind a UV-transmitting (UV+ filter, revealed a significant effect of lighting condition during rearing on association preference. Test fish that had been deprived of UV spent significantly more time near the UV- shoal compared to the test fish reared under full-spectrum lighting conditions. The results are discussed with respect to plasticity of the visual system and environmental lighting conditions.

Synthesis and controlled self-assembly of UV-responsive gold nanoparticles in block copolymer templates.

Science.gov (United States)

Song, Dong-Po; Wang, Xinyu; Lin, Ying; Watkins, James J

2014-11-06

We demonstrate the facile synthesis of gold nanoparticles (GNPs) functionalized by UV-responsive block copolymer ligands, poly(styrene)-b-poly(o-nitrobenzene acrylate)-SH (PS-b-PNBA-SH), followed by their targeted distribution within a lamellae-forming poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer. The multilayer, micelle-like structure of the GNPs consists of a gold core, an inner PNBA layer, and an outer PS layer. The UV-sensitive PNBA segment can be deprotected into a layer containing poly(acrylic acid) (PAA) when exposed to UV light at 365 nm, which enables the simple and precise tuning of GNP surface properties from hydrophobic to amphiphilic. The GNPs bearing ligands of different chemical compositions were successfully and selectively incorporated into the PS-b-P2VP block copolymer, and UV light showed a profound influence on the spatial distributions of GNPs. Prior to UV exposure, GNPs partition along the interfaces of PS and P2VP domains, while the UV-treated GNPs are incorporated into P2VP domains as a result of hydrogen bond interactions between PAA on the gold surface and P2VP domains. This provides an easy way of controlling the arrangement of nanoparticles in polymer matrices by tailoring the nanoparticle surface using UV light.

UV-B Irradiation Changes Specifically the Secondary Metabolite Profile in Broccoli Sprouts: Induced Signaling Overlaps with Defense Response to Biotic Stressors

Science.gov (United States)

Mewis, Inga; Schreiner, Monika; Nguyen, Chau Nhi; Krumbein, Angelika; Ulrichs, Christian; Lohse, Marc; Zrenner, Rita

2012-01-01

Only a few environmental factors have such a pronounced effect on plant growth and development as ultraviolet light (UV). Concerns have arisen due to increased UV-B radiation reaching the Earth’s surface as a result of stratospheric ozone depletion. Ecologically relevant low to moderate UV-B doses (0.3–1 kJ m–2 d–1) were applied to sprouts of the important vegetable crop Brassica oleracea var. italica (broccoli), and eco-physiological responses such as accumulation of non-volatile secondary metabolites were related to transcriptional responses with Agilent One-Color Gene Expression Microarray analysis using the 2×204 k format Brassica microarray. UV-B radiation effects have usually been linked to increases in phenolic compounds. As expected, the flavonoids kaempferol and quercetin accumulated in broccoli sprouts (the aerial part of the seedlings) 24 h after UV-B treatment. A new finding is the specific UV-B-mediated induction of glucosinolates (GS), especially of 4-methylsulfinylbutyl GS and 4-methoxy-indol-3-ylmethyl GS, while carotenoids and Chl levels remained unaffected. Accumulation of defensive GS metabolites was accompanied by increased expression of genes associated with salicylate and jasmonic acid signaling defense pathways and up-regulation of genes responsive to fungal and bacterial pathogens. Concomitantly, plant pre-exposure to moderate UV-B doses had negative effects on the performance of the caterpillar Pieris brassicae (L.) and on the population growth of the aphid Myzus persicae (Sulzer). Moreover, insect-specific induction of GS in broccoli sprouts was affected by UV-B pre-treatment. PMID:22773681

The effect of exposure to enhanced UV-B radiation on the penetration of monochromatic and polychromatic UV-B radiation in leaves of Brassica napus

International Nuclear Information System (INIS)

Cen, Y.-P.; Bornman, J.F.

1993-01-01

Using quartz optical fibres, penetration of both monochromatic (310 nm) and polychromatic UV-B (280–320 nm) radiation in leaves of Brassica napus L. (cv. Ceres) was measured. Plants were grown under either visible light (750 μmol m −2 s −1 photosynthetically active radiation) or with the addition of 8. 9 KJ m −2 day −1 biologically effective UV-B (UV-B BE ) radiation. Results showed that of the 310 nm radiation that penetreated the leaf, 90% was within the intial one third of the leaf with high attenuation in the leaf epidermis, especially in UV-treated plants. Polychromatic UV-B radiation, relative to incident radiation, showed a relatively uniform spectral distribution within the leaf, except for collimated radiation. Over 30% of the UV-screening pigments in the leaf, including flavonoids, were found in the adaxial epidermal layer, making this layer less transparent to UV-B radiation than the abaxial epidermis, which contained less than 12% of the UV-screening pigments. UV-screening pigments increased by 20% in UV-treated leaves relative to control leaves. Densely arranged epicuticular wax on the adaxial leaf surface of UV-treated plants may have further decreased penetration of UV-B radiation by reflectance. An increased leaf thickness, and decreases in leaf area and leaf dry weight were also found for UV-treated plants. (author)

UV-induced transcription from the human immunodeficiency virus type 1 (HIV-1) long terminal repeat and UV-induced secretion of an extracellular factor that induces HIV-1 transcription in nonirradiated cells

International Nuclear Information System (INIS)

Stein, B.; Kraemer, M.R.; Rahmsdorf, H.J.; Ponta, H.; Herrlich, P.

1989-01-01

UV irradiation, but not visible sunlight, induces the transcription of human immunodeficiency virus type 1 (HIV-1). Chimeric constructs carrying all or parts of the HIV-1 long terminal repeat linked to an indicator gene were transfected into HeLa cells or murine and human T-cell lines, and their response to irradiation was tested. The cis-acting element conferring UV responsiveness is identical to the sequence binding transcription factor NF kappa B. UV irradiation enhances NF kappa B binding activity as assayed by gel retardation experiments. Interestingly, the requirement for UV irradiation can be replaced by cocultivation of transfected cells with UV-irradiated nontransfected (HIV-1-negative) cells. A UV-induced extracellular protein factor is detected in the culture medium conditioned by UV-treated cells. The factor is produced upon UV irradiation by several murine and human cell lines, including HeLa, Molt-4, and Jurkat, and acts on several cells. These data suggest that the UV response of keratinocytes in human skin can be magnified and spread to deeper layers that are more shielded, including the Langerhans cells, and that this indirect UV response may contribute to the activation of HIV-1 in humans

Dose/dose-rate responses of shrimp larvae to UV-B radiation

International Nuclear Information System (INIS)

Damkaer, D.M.

1981-01-01

Previous work indicated dose-rate thresholds in the effects of UV-B on the near-surface larvae of three shrimp species. Additional observations suggest that the total dose response varies with dose-rate. Below 0.002 Wm -2 sub([DNA]) irradiance no significant effect is noted in activity, development, or survival. Beyond that dose-rate threshold, shrimp larvae are significantly affected if the total dose exceeds about 85 Jm -2 sub([DNA]). Predictions cannot be made without both the dose-rate and the dose. These dose/dose-rate thresholds are compared to four-year mean dose/dose-rate solar UV-B irradiances at the experimental site, measured at the surface and calculated for 1 m depth. The probability that the shrimp larvae would receive lethal irradiance is low for the first half of the season of surface occurrence, even with a 44% increase in damaging UV radiation. (orig.)

Dose/dose-rate responses of shrimp larvae to UV-B radiation

Energy Technology Data Exchange (ETDEWEB)

Damkaer, D.M.; Dey, D.B.; Heron, G.A.

1981-01-01

Previous work indicated dose-rate thresholds in the effects of UV-B on the near-surface larvae of three shrimp species. Additional observations suggest that the total dose response varies with dose-rate. Below 0.002 Wm/sup -2/sub((DNA)) irradiance no significant effect is noted in activity, development, or survival. Beyond that dose-rate threshold, shrimp larvae are significantly affected if the total dose exceeds about 85 Jm/sup -2/sub((DNA)). Predictions cannot be made without both the dose-rate and the dose. These dose/dose-rate thresholds are compared to four-year mean dose/dose-rate solar UV-B irradiances at the experimental site, measured at the surface and calculated for 1 m depth. The probability that the shrimp larvae would receive lethal irradiance is low for the first half of the season of surface occurrence, even with a 44% increase in damaging UV radiation.

Photonic crystal structures on nonflat surfaces fabricated by dry lift-off soft UV nanoimprint lithography

International Nuclear Information System (INIS)

Sun, Tangyou; Xu, Zhimou; Xu, Haifeng; Zhao, Wenning; Wu, Xinghui; Liu, Sisi; Ma, Zhichao; He, Jian; Liu, Shiyuan; Peng, Jing

2013-01-01

The surface nonflatness induced from the material itself or the production atmosphere can lead to serious non-uniformity consequences in nanoimprint lithography (NIL) which is used for providing a low cost and high throughput nano-fabrication process. In this paper, soft UV NIL (SUNIL) processes are used for photonic crystal (PC) pattern transfer of a GaN-based light-emitting diode (LED) with patterned sapphire substrate (PSS). The results reveal a significant incompatibility between the conventional SUNIL and the nonflat p-GaN surface. Ellipse-shaped rather than circle-shaped PC structure is obtained on the p-GaN surface due the deformation of the soft mold in nonflat NIL. A dry lift-off (DLO) SUNIL is proposed to overcome the non-uniformity issue in nonflat NIL as well as the collapse problem of the free-standing pillar-shaped resist in wet lift-off. The photoluminescence enhancements of the LED fabricated by the DLO SUNIL method compared to those with conventional SUNIL and unpatterned LED are 1.41 fold and 3.48 fold, respectively. Further study shows that the DLO SUNIL is applicable in the fabrication of the PC structure with tunable duty cycle via one single initial PC mold. (paper)

UV photooxidation induced structural and photoluminescence behaviors in vapor-etching based porous silicon

International Nuclear Information System (INIS)

Aouida, S.; Saadoun, M.; Ben Saad, K.; Bessais, B.

2006-01-01

In this paper, we investigate the effect of UV irradiation on Vapor-Etching (VE) based Porous Silicon (PS) structure and luminescence under controlled atmosphere (N 2 , air, O 2 ). The oxidation evolution is monitored by Fourier transform infrared (FTIR) spectroscopy. FTIR measurements show that the SiH x bond, initially present in the freshly prepared PS layers, decreased progressively with UV irradiation time until they completely disappear. We found that this treatment accelerates the oxidation process. SiO x structures appear and gradually become dominant as regard to the SiH x species, while UV irradiation is in progress. Generally, the photoluminescence (PL) intensity of the PS layer decreases instantaneously at the starting by the UV excitation and stabilizes after a period depending on the ambient gas and the specific surface area of the porous structure. Further UV exposure leads to a linear decrease of the PL intensity due to change of surface passivation from SiH x to O y SiH x . After less than 100 min of UV irradiation, the PL intensity exhibits an exponential decay. UV exposure in air and O 2 leads approximately to the same PL behavior, although faster PL intensity decrease was observed under O 2 -rich ambient. This was explained as being due to intense hydrogen desorption in presence of oxygen. Correlations of PL results with FTIR measurements show that surface passivation determine the electronic states of silicon nano-crystallites and influence the photoluminescence efficiency

Perchlorates on Mars enhance the bacteriocidal effects of UV light.

Science.gov (United States)

Wadsworth, Jennifer; Cockell, Charles S

2017-07-06

Perchlorates have been identified on the surface of Mars. This has prompted speculation of what their influence would be on habitability. We show that when irradiated with a simulated Martian UV flux, perchlorates become bacteriocidal. At concentrations associated with Martian surface regolith, vegetative cells of Bacillus subtilis in Martian analogue environments lost viability within minutes. Two other components of the Martian surface, iron oxides and hydrogen peroxide, act in synergy with irradiated perchlorates to cause a 10.8-fold increase in cell death when compared to cells exposed to UV radiation after 60 seconds of exposure. These data show that the combined effects of at least three components of the Martian surface, activated by surface photochemistry, render the present-day surface more uninhabitable than previously thought, and demonstrate the low probability of survival of biological contaminants released from robotic and human exploration missions.

Characteristics of UV-MicroO3 Reactor and Its Application to Microcystins Degradation during Surface Water Treatment

Directory of Open Access Journals (Sweden)

Guangcan Zhu

2015-01-01

Full Text Available The UV-ozone (UV-O3 process is not widely applied in wastewater and potable water treatment partly for the relatively high cost since complicated UV radiation and ozone generating systems are utilized. The UV-microozone (UV-microO3, a new advanced process that can solve the abovementioned problems, was introduced in this study. The effects of air flux, air pressure, and air humidity on generation and concentration of O3 in UV-microO3 reactor were investigated. The utilization of this UV-microO3 reactor in microcystins (MCs degradation was also carried out. Experimental results indicated that the optimum air flux in the reactor equipped with 37 mm diameter quartz tube was determined to be 18∼25 L/h for efficient O3 generation. The air pressure and humidity in UV-microO3 reactor should be low enough in order to get optimum O3 output. Moreover, microcystin-RR, YR, and LR (MC-RR, MC-YR, and MC-LR could be degraded effectively by UV-microO3 process. The degradation of different MCs was characterized by first-order reaction kinetics. The pseudofirst-order kinetic constants for MC-RR, MC-YR, and MC-LR degradation were 0.0093, 0.0215, and 0.0286 min−1, respectively. Glucose had no influence on MC degradation through UV-microO3. The UV-microO3 process is hence recommended as a suitable advanced treatment method for dissolved MCs degradation.

Enhanced expression of transferrin receptor confers UV-resistance in human and monkey cells

International Nuclear Information System (INIS)

Chen, Zheng; Nomura, Jun; Suzuki, Toshikazu; Suzuki, Nobuo

2005-01-01

One of the most intriguing biological subjects is cell-surface molecules that regulate the susceptibility of human cells to cell-killing effects after irradiation with far-ultraviolet light (UV, principally 254 nm wavelength). Human RSa cells have unusual sensitivity to UV-induced cell-killing. We searched for molecules on the cell-surface of RSa cells that were present in different amounts as compared to a variant of these cells, UV r -1 cells, which have increased resistance to UV cell-killing. Among the 21 molecules examined, the amount of transferrin receptor (TfR) protein was found to be 2-fold higher in UV r -1 cells compared with in RSa cells. The amounts of this protein were also higher in the UV-resistant hematopoietic cell lines, CEM6 and Daudi, as compared to the UV-sensitive cell lines, Molt4 and 697. Culturing of UV r -1 cells in a medium containing anti-transferrin antibodies resulted in sensitization of the cells to UV cell-killing as demonstrated by colony formation assay. Similar results were observed by treatment of the cells with TfR siRNA. In contrast, overexpression of TfR protein led to a resistance to UV cell-killing in RSa cells and monkey COS7 cells as demonstrated by both colony formation and apoptosis assay. In TfR-overexpressing cells, reduction of p53 and Bax protein was observed after UV-irradiation. Thus, TfR expression appears to be involved in the regulation of UV-resistance, possibly via modulation of the amount of p53 and Bax protein. (author)

Region-selective electroless gold plating on polycarbonate sheets by UV-patterning in combination with silver activating

Energy Technology Data Exchange (ETDEWEB)

Zhou Qinghua [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China); Chen Hengwu, E-mail: hwchen@zju.edu.c [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China); Wang Yi [Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Zijin' gang Campus, Hangzhou 310058 (China)

2010-02-28

A simple, time- and cost-effective approach for region-selective metalization of polycarbonate (PC) surface has been established by combining photoresist-free UV-patterning with tin- and amine-free silver activating and electroless gold plating. The surface of PC sheets was exposed to the UV lights emitted from a low-pressure mercury lamp through a photomask, the micro pattern on the mask being transferred to the PC surface due to the photochemical generation of carboxyl groups on the UV-exposed region. The UV-exposed PC sheets were then treated with an ammoniacal AgNO{sub 3} solution, so that the silver ions were chemisorbed by the photochemically generated carboxyl groups. When the Ag{sup +}-adsorbed PC sheet was immersed into an electroless gold plating bath, shiny gold film quickly deposited on the UV-exposed region, resulting in the formation of a micro gold devices on the PC surface. The whole plating process including UV-exposure, surface activating and gold plating can be completed in about 3-4 h. Attenuated total reflection Fourier transformation infrared spectrometer (ATR-FT-IR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and scanning electron microscope (SEM) were employed to trace the surface change during the plating process. Cyclic voltammetry (CV) and Scotch-tape test were employed to characterize the electrochemical properties and adhesion strength of the prepared micro gold devices, respectively. The prepared micro gold electrodes were demonstrated for amperometric detection of hydrogen peroxide.

Effects of stron UV-B radiation on air chemistry and climate; Auswirkungen verstaerkter UV-B-Strahlung auf Luftchemie und Klima

Energy Technology Data Exchange (ETDEWEB)

Schoenemeyer, T.; Seidl, W.; Forkel, R.; Kuhn, M.; Wehrhahn, J.; Grell, G.

1998-07-01

Effects of enhanced UV radiation on air chemistry, climate and climate change were investigated, and its interactions with other environmental problems like acidification of soil and surface water, reduction in the variety of species, and desertification were gone into. [German] In der vorliegenden Arbeit wurden die bisher vorliegenden Erkenntnisse ueber die Auswirkungen erhoehter UV-Strahlung infolge des Abbaus von Ozon in der Stratosphaere auf Luftchemie und Klima zusammengetragen. Die Problematik wird in ihrer ganzen Breite beleuchtet und dabei deutlich gemacht, ueber welche zahlreichen Mechanismen eine erhoehte UV-Strahlung auch zu Klimaaenderungen fuehren kann. Dies unterstreicht die Notwendigkeit, Verknuepfungen mit anderen Umweltproblemen wie der Versauerung des Bodens und von Gewaessern, der Abnahme der Artenvielfalt sowie der zunehmenden Wuestenbildung herzustellen. (orig.)

Adsorption characteristics of Au nanoparticles onto poly(4-vinylpyridine) surface revealed by QCM, AFM, UV/vis, and Raman scattering spectroscopy.

Science.gov (United States)

Kim, Kwan; Ryoo, Hyunwoo; Lee, Yoon Mi; Shin, Kuan Soo

2010-02-15

In this work, we report that the adsorption and aggregation processes of Au nanoparticles on a polymer surface can be monitored by means of surface-enhanced Raman scattering (SERS) spectroscopy. Specifically, we were able to analyze the adsorption process of citrate-stabilized Au nanoparticles onto a film of poly(4-vinylpyridine) (P4VP) by taking a series of SERS spectra, during the self-assembly of Au nanoparticles onto the polymer film. In order to better analyze the SERS spectra, we separately conducted quartz crystal microbalance (QCM), UV/vis spectroscopy, and atomic force microscope (AFM) measurements. The adsorption kinetics revealed by QCM under the in situ conditions was in fair agreement with that determined by the ex situ AFM measurement. The number of Au nanoparticles adsorbed on P4VP increased almost linearly with time: 265 Au nanoparticles per 1microm(2) were adsorbed on the P4VP film after 6h of immersion. The SERS signal measured in the ex situ condition showed a more rapid increase than that of QCM; however, its increasing pattern was quite similar to that of UV/vis absorbance at longer wavelengths, suggesting that Au nanoparticles actually became agglomerated on P4VP. Copyright 2009 Elsevier Inc. All rights reserved.

Enhanced UV exposure on a ski-field compared with exposures at sea level.

Science.gov (United States)

Allen, Martin; McKenzie, Richard

2005-05-01

Personal erythemal UV monitoring badges, which were developed to monitor the UV exposure of school children, were used to measure UV exposures received by one of the authors (MA) at the Mt Hutt ski-field, in New Zealand. These were then compared with measurements taken at the same times from a nearby sea level site in Christchurch city. The badges were designed to give instantaneous readings of erythemally-weighted (i.e., "sun burning") UV radiation and were cross-calibrated against meteorological grade UV instruments maintained by the National Institute of Water & Atmospheric Research (NIWA). All skiing and calibration days were clear and almost exclusively cloud free. It was found that the UV maxima for horizontal surfaces at the ski-field (altitude approximately 2 km) were 20-30% greater than at the low altitude site. Larger differences between the sites were observed when the sensor was oriented perpendicular to the sun. The personal doses of UV received by a sensor on the skier's lapel during two days of skiing activity were less than those received by a stationary detector on a horizontal surface near sea level. The exposures depended strongly on the time of year, and in mid-October the maximum UV intensity on the ski-field was 60% greater than in mid-September. The UV exposure levels experienced during skiing were smaller than the summer maxima at low altitudes.

A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

Science.gov (United States)

Wallett, Thomas M.

2009-01-01

This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

Penetration of UV-A, UV-B, blue, and red light into leaf tissues of pecan measured by a fiber optic microprobe system

Science.gov (United States)

Qi, Yadong; Bai, Shuju; Vogelmann, Thomas C.; Heisler, Gordon M.

2003-11-01

The depth of light penetration from the adaxial surfaces of the mature leaves of pecan (Carya illinoensis) was measured using a fiber optic microprobe system at four wavelengths: UV-B (310nm), UV-A (360 nm), blue light (430nm), and red light (680nm). The average thickness of the leaf adaxial epidermal layer was 15um and the total leaf thickness was 219um. The patterns of the light attenuation by the leaf tissues exhibited strong wavelength dependence. The leaf adaxial epidermal layer was chiefly responsible for absorbing the UV-A UV-B radiation. About 98% of 310 nm light was steeply attenuated within the first 5 um of the adaxial epidermis; thus, very little UV-B radiation was transmitted to the mesophyll tissues where contain photosynthetically sensitive sites. The adaxial epidermis also attenuated 96% of the UV-A radiation. In contrast, the blue and red light penetrated much deeper and was gradually attenutated by the leaves. The mesophyll tissues attenuated 17% of the blue light and 42% of the red light, which were available for photosynthesis use. Since the epidermal layer absorbed nearly all UV-B light, it acted as an effective filter screening out the harmful radiation and protecting photosynthetically sensitive tissues from the UV-B damage. Therefore, the epidermal function of the UV-B screening effectiveness can be regarded as one of the UV-B protection mechanisms in pecan.

Multispectral UV imaging for determination of the tablet coating thickness

DEFF Research Database (Denmark)

Novikova, Anna; Carstensen, Jens Michael; Zeitler, J. Axel

2017-01-01

The applicability of off-line multispectral ultraviolet (UV) imaging in combination with multivariate data analysis was investigated to determine the coating thickness and its distribution on the tablet surface during lab scale coating. The UV imaging results were compared with the weight gain...... measured for each individual tablet and the corresponding coating thickness and its distribution measured by terahertz pulsed imaging (TPI). Three different tablet formulations were investigated, two of which contained UV active tablet cores. Three coating formulations were applied: Aquacoat® ECD (a mainly...... translucent coating) and Eudragit® NE (a turbid coating containing solid particles). It was shown that UV imaging is a fast and non-destructive method to predict individual tablet weight gain as well as coating thickness. The coating thickness distribution profiles determined by UV imaging correlated...

Effects of ozone depletion and UV-B radiation on humans and the environment

Energy Technology Data Exchange (ETDEWEB)

Solomon, K.R. [Guelph Univ., ON (Canada). Centre for Toxicology

2008-03-15

This paper summarized current research related to the effects of ultraviolet (UV-B) radiation on human health and the environment. Effects included direct responses in human as well as effects on biogeochemistry and the environmental cycling of substances. UV radiation has many harmful effects on the skin, eyes, and immune systems of humans. Skin cancer is a leading cause of death among fair-skinned populations exposed to UV radiation. The role of UV radiation in cataract formation was discussed, as well as issues related to the suppression of immune responses. The link between sunlight exposure and vitamin D levels in human populations was examined. The effects of UV radiation on terrestrial and aquatic ecosystems were reviewed. Issues related to biogeochemistry and atmospheric processes were discussed. The review suggested that changes in the intensity of solar UV radiation due to ozone depletion will have important repercussions for all organisms on the planet. It was concluded that the combined effects of UV-B radiation and climate change will not be easy to predict. 201 refs., 4 figs.

UV-sensitive optical sensors based on ITO-gallium phosphide heterojunctions

Energy Technology Data Exchange (ETDEWEB)

Malik, Oleksandr; Hidalga-Wade, F. Javier de la; Zuniga-Islas, Carlos; Abundis Patino, Jesus H. [National Institute for Astrophysics, Optics, and Electronics (INAOE), Puebla (Mexico)

2010-04-15

Design and characteristics of wide-band UV sensors based on ITO/GaP heterostructures are discussed. Such sensors have perfect electrical parameters and high UV-visible sensitivity in comparison with surface-barrier structures using a semi-transparent thin metal film as an electrode. Many applications require UV sensors with an effective rejection of visible radiation and a wide temperature operating interval. For this aim, the theoretical modelling of extreme selective optical sensors with a double Ag/ITO thin film on the GaP surface, in which the thin silver film serves as a narrow bandpass filter at 320 nm, has been conducted. With this modelling the optimal thickness combination for the silver and ITO films was found for the maximum rejection of the sensitivity to visible radiation (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Detection of Explosives on Surfaces Using UV Raman Spectroscopy: Effect of Substrate Color

Science.gov (United States)

2017-10-01

257.23-nm excitation (25 mW at the laser) using 2.5-s integration time and 100 accumulations. Each spectrum is offset by 400 counts from the one...tens of meters have been reported. The testing of UV Raman spectroscopy systems for standoff UV Raman spectroscopy has been generally limited to bare...SP2500A 500-mm focal length monochromator and a PIXIS 400 × 3048 pixel charge-coupled device (CCD) camera (Princeton Instruments, Trenton, NJ). An

Using an on-line UV-C apparatus to treat harvested fruit for controlling postharvest decay

International Nuclear Information System (INIS)

Wilson, C.L.; Upchurch, B.; El Ghaouth, A.; Stevens, C.; Khan, V.; Droby, S.; Chalutz, E.

1997-01-01

An apparatus was designed to deliver low-dose UV-C light to the surface of fruit on a processing line and tested for its control of postharvest decay. It consisted of a row of UV-C emitting lamps mounted on a frame above a conveyer belt that transported the fruit. The dosage of the UV-C light delivered to the fruit surface was regulated by varying the speed of the conveyor belt. Postharvest decay after 28 days storage of 'Empire' apples was reduced 52% relative to the untreated checks when the fruit were conveyed at 6.2 m · min -1 (1.38 kJ · m -2 dose) under the UV-C apparatus. Factors affecting the practical application of UV-C irradiation of fruit for controlling postharvest decay are discussed

UV irradiation improves the bond strength of resin cement to fiber posts.

Science.gov (United States)

Zhong, Bo; Zhang, Yong; Zhou, Jianfeng; Chen, Li; Li, Deli; Tan, Jianguo

2011-01-01

The purpose is to evaluate the effect of UV irradiation on the bond strength between epoxy-based glass fiber posts and resin cement. Twelve epoxy-based glass fiber posts were randomly divided into three groups. Group 1 (Cont.): No surface treatment. Group 2 (Low-UV): UV irradiation was conducted from a distance of 10 cm for 10 min. Group 3 (High-UV): UV irradiation was conducted from a distance of 1 cm for 3 min. A resin cement (CLEARFIL SA LUTING) was used for the post cementation to form resin slabs which contained fiber posts in the center. Microtensile bond strengths were tested and the mean bond strengths (MPa) were 18.81 for Cont. group, 23.65 for Low-UV group, 34.75 for High-UV group. UV irradiation had a significant effect on the bond strength (pUV irradiation demonstrates its capability to improve the bond strength between epoxy-based glass fiber posts and resin cement.

Design of tunable ultraviolet (UV) absorbance by controlling the Agsbnd Al co-sputtering deposition

Science.gov (United States)

Zhang, Xin-Yuan; Chen, Lei; Wang, Yaxin; Zhang, Yongjun; Yang, Jinghai; Choi, Hyun Chul; Jung, Young Mee

2018-05-01

Changing the structure and composition of a material can alter its properties; hence, the controlled fabrication of metal nanostructures plays a key role in a wide range of applications. In this study, the structure of Agsbnd Al ordered arrays fabricated by co-sputtering deposition onto a monolayer colloidal crystal significantly increased its ultraviolet (UV) absorbance owing to a tunable localized surface plasmon resonance (LSPR) effect. By increasing the spacing between two nanospheres and the content of aluminum, absorbance in the UV region could be changed from UVA (320-400 nm) to UVC (200-275 nm), and the LSPR peak in the visible region gradually shifted to the UV region. This provides the potential for surface-enhanced Raman scattering (SERS) in both the UV and visible regions.

Impact of fouling on UV effectiveness

International Nuclear Information System (INIS)

Dykstra, T.S.; Chauret, C.

2002-01-01

In recent years ultraviolet light has gained in popularity as an attractive disinfection alternative due to its ability to inactivate bacteria and viruses. UV light has the potential to inactivate Cryptosporidium parvum and Giardia lamblia with a very low potential for the formation of harmful disinfection by-products. Previous studies have reported that particulate material present in the water can act to reduce the exposure of UV light to the receiving waters and that the interference of organic particles can serve to protect bacteria and viruses from intended disinfection. Disinfection capacity can also be reduced by organics in the source water that can accumulate on the surface of quartz sleeves. The purpose of this study was to determine the ability of a medium pressure UV light, at drinking water treatment levels, to inactivate MS 2 bacteriophage after a quartz tube has been fouled with organic rich source water for a 12- week period. To this end the inactivation of MS 2 was determined under clean and fouled conditions, in the presence and absence of humic rich water. The effect of lamp age on inactivation was also investigated. The results suggest that organic fouling of a quartz tube has a significant impact on the disinfection capacity of a medium pressure UV lamp. The presence of organics in the source water also plays a significant role in reducing the capacity of UV for bacterial and viral disinfection. Lamp age also seems to have some effect on the efficiency of UV disinfection. (author)

Large area UV light source with a semiconductor cathode

International Nuclear Information System (INIS)

Salamov, B. G.; Ciftci, Y. Oe.; Colakoglu, K.

2002-01-01

The light emission (LE) in the UV and visible (blue) range generated by a planar gas discharge system (PGDS) with a semiconductor cathode (SC) are studied. New light source offer high-intensity narrow-band emission at various UV and visible wavelengths (330 - 440 nm). Spectra in N 2 is presented, as well as intensity vs pressure curves for the main peaks of the spectrum. The use of source offers several advantages: PGDS can be extremely efficient energy converters transforming and amplifying a relatively low-powered photon flux incident on the receiving surface of the SC into a flux of high-energy particles over extended areas, i.e. electron, ions, photons. Thus, extremely bright UV and visible sources can be built. LE characteristics of the space in the PGDS are complex, depending on the emitting medium and species. By using the IR light to excite the SC of the system, we have shown that the discharge light emission (DLE) of the device with the N 2 in the gap can serve as an efficient source of the UV radiation if gas pressure and electric field are sufficiently high. This is realized due to the effect of the stabilisation of the spatially homogeneous mode of the discharge in a narrow gap with a large emitting area of SC. Special features of DLE render it highly promising for the development of sources with a large area of the emitting surface, high spatial uniformity of UV radiation, and fast dynamics of these devices. This low cost, high power light sources can provide an interesting alternative to conventional UV lamps

Preparation of protein- and cell-resistant surfaces by hyperthermal hydrogen induced cross-linking of poly(ethylene oxide).

Science.gov (United States)

Bonduelle, Colin V; Lau, Woon M; Gillies, Elizabeth R

2011-05-01

The functionalization of surfaces with poly(ethylene oxide) (PEO) is an effective means of imparting resistance to the adsorption of proteins and the attachment and growth of cells, properties that are critical for many biomedical applications. In this work, a new hyperthermal hydrogen induced cross-linking (HHIC) method was explored as a simple one-step approach for attaching PEO to surfaces through the selective cleavage of C-H bonds and subsequent cross-linking of the resulting carbon radicals. In order to study the effects of the process on the polymer, PEO-coated silicon wafers were prepared and the effects of different treatment times were investigated. Subsequently, using an optimized treatment time and a modified butyl polymer with increased affinity for PEO, the technique was applied to butyl rubber surfaces. All of the treated surfaces exhibited significantly reduced protein adsorption and cell growth relative to control surfaces and compared favorably with surfaces that were functionalized with PEO using conventional chemical methods. Thus HHIC is a simple and effective means of attaching PEO to non-functional polymer surfaces.

Mutagenicity of monoadducts and cross-links induced in Aspergillus nidulans by 8-methoxypsoralen plus 365 nm radiation

International Nuclear Information System (INIS)

Scott, B.R.; Maley, M.A.

1981-01-01

8-Methoxypsoralen plus 365 nm radiation induces mutation at the methionine supressor loci of Aspergillus inhibitor-deficient conidia at low doses of near-UV radiation with one-hit kinetics and at higher near-UV radiation doses with two-hit kinetics. These results and others suggest that both monoadducts and cross-links, formed by 8-methoxypsoralen and DNA upon exposure to UV radiation, are capable of inducing mutation. Evidence is also presented that induced furocoumarin cross-links are responsible for the inactivation of the Aspergillus conidium. (author)

The dose-response relationship for UV-tumorigenesis

International Nuclear Information System (INIS)

Gruijl, F.R. de.

1982-01-01

The main objective of the investigations was to extend the knowledge on experimental UV-carcinogenesis and to use the experimental results as guidelines for developing a dose-response model for UV-carcinogenesis. The animal experiments carried out were all long-term ones. It was decided that - in anticipation of the data to be obtained - a model for such an assessment should be developed using the experimental results available at the start of the present study (1977). This initial study is presented. The results of two animal experiments are presented, which show that UV radiation is capable of inducing a systemic effect that enhances the de novo formation of UV induced tumors. The results of the main experiment are presented. In this experiment groups of mice were subjected to daily exposure to a certain dose of UV radiation in order to find the dose-response relationship. The relation between the daily dose and the duration of the treatment till the appearance of tumors (for instance, as measured by the yield) was ascertained for tumors of different sizes. It appears that the growth of a tumor is dose-independent, and, therefore, only the initiation of a tumor is dose-dependent. Finally an experiment is presented in which it was measured that, if a mouse is subjected to daily UV exposure, the transmission of the epidermis in the shortwave UV region decreases continuously. This decrease is due to hyperplasia of the epidermis, i.e., thickening of the epidermis by an increase in the number of cells per unit surface area. (Auth.)

UV-absorbing compounds in subarctic herbarium bryophytes

Energy Technology Data Exchange (ETDEWEB)

Huttunen, S. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)]. E-mail: satu.huttunen@oulu.fi; Lappalainen, N.M. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland); Turunen, J. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)

2005-01-01

The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A{sub 280-320nm}) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time.

UV-absorbing compounds in subarctic herbarium bryophytes

International Nuclear Information System (INIS)

Huttunen, S.; Lappalainen, N.M.; Turunen, J.

2005-01-01

The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A 280-320nm ) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time

Nonlinear (MARS modeling of long-term variations of surface UV-B radiation as revealed from the analysis of Belsk, Poland data for the period 1976–2000

Directory of Open Access Journals (Sweden)

J. W. Krzyścin

Full Text Available A new, powerful statistical technique, multivariate adaptive regression splines (MARS, is applied to reproduce monthly fractional deviations of UV-B doses over Belsk, Poland, during the snowless (May–October part of the year in the period 1976–2000. Two kinds of regressors were used: local ones (total ozone, percentage of sky covered by low-, mid-, high-level clouds or total solar radiation over Belsk and non-local ones, i.e. those describing the long-distance forcings on the surface UV-B due to changes in the global atmospheric circulation. Standard indices of the Quasi-Biennial, North Atlantic, El Niño-Southern Oscillations, and the 11-year solar activity were used as non-local regressors. The results there indicate that the MARS procedure is able to reproduce the observed year-to-year and decadal oscillations in the UV data. The MARS model yields better model-observation agreement than an ordinary least-squares fit based on the same set of regressors. It is found that MARS is capable of handling interactions between the local and non-local regressors, suggesting a possible nonlinear nature of connections between variables characterizing the atmospheric transparency over Belsk and the long-distance forcings. MARS enables a reconstruction of the surface UV-B variations over any site based on the cloud and ozone data presently stored on web pages.

Key words. Atmospheric composition and structure (aerosols and particles; biosphere-atmosphere interactions

Advances in UV-Plasmonics: A Detailed Analysis of Metallic Materials as Candidates for New Applications in Nanothecnology

Science.gov (United States)

2014-08-26

Indium, Rhodium, Ruthenium, Tungsten, Titanium, Chromium, Palladium, Copper, Platinum and Magnesium . These have been chosen because all of them...performance. vii. Considering that the observed behaviors occur precisely where UV surface-enhanced Raman spectra indicated strong local field...research objective was centered on the UV plasmonic properties of Rh NPs by means of surface-enhanced Raman spectroscopy, surface-enhanced

Alleviation of UV-B stress in Arabidopsis using tea catechins | Lee ...

African Journals Online (AJOL)

Ultraviolet-B (UV-B) has been confirmed to be harmful to living organisms and it is of concern that the amount of UV-B radiation reaching the earth's surface is increasing because of the depletion of the stratospheric ozone layer. Effect of different levels of tea catechins on morphological damage and expression of chalcone ...

p38-MK2 signaling axis regulates RNA metabolism after UV-light-induced DNA damage

DEFF Research Database (Denmark)

Borisova, Marina E; Voigt, Andrea; Tollenaere, Maxim A X

2018-01-01

quantitative phosphoproteomics and protein kinase inhibition to provide a systems view on protein phosphorylation patterns induced by UV light and uncover the dependencies of phosphorylation events on the canonical DNA damage signaling by ATM/ATR and the p38 MAP kinase pathway. We identify RNA-binding proteins......Ultraviolet (UV) light radiation induces the formation of bulky photoproducts in the DNA that globally affect transcription and splicing. However, the signaling pathways and mechanisms that link UV-light-induced DNA damage to changes in RNA metabolism remain poorly understood. Here we employ...

UV-associated decline in systemic folate: implications for human nutrigenetics, health, and evolutionary processes.

Science.gov (United States)

Lucock, Mark; Beckett, Emma; Martin, Charlotte; Jones, Patrice; Furst, John; Yates, Zoe; Jablonski, Nina G; Chaplin, George; Veysey, Martin

2017-03-01

The purpose of this study was to examine whether UV exposure alters folate status according to C677T-MTHFR genotype, and to consider the relevance of this to human health and the evolutionary model of skin pigmentation. Total Ozone Mapping Spectrometer (TOMS) satellite data were used to examine surface UV-irradiance, as a marker of UV exposure, in a large (n = 649) Australian cross-sectional study population. PCR/RFLP analysis was used to genotype C677T-MTHFR. Overall, cumulative UV-irradiance (42 and 120 days pre-clinic) was significantly negatively related to red cell folate (RCF) levels. When the cohort was stratified by MTHFR-C677T genotype, the relationship between UV-irradiance (42 days pre-clinic) and RCF remained significant only in the cohorts containing carriers of the T allele. Statistically significant z-score statistics and interaction terms from genotype and UV-irradiance (p-interaction) demonstrated that genotype did modify the effect of UV-irradiance on RCF, with the largest effect of UV being demonstrated in the 677TT-MTHFR subjects. Data provide strong evidence that surface UV-irradiance reduces long-term systemic folate levels, and that this is influenced by the C677T-MTHFR gene variant. We speculate this effect may be due to 677TT-MTHFR individuals containing more 5,10CH 2 -H 4 PteGlu, and that this folate form may be particularly UV labile. Since UV-irradiance lowers RCF in an MTHFR genotype-specific way, there are likely implications for human health and the evolution of skin pigmentation. © 2016 Wiley Periodicals, Inc.

AquaDiva: Understanding the Link between the Surface and Subsurface Biogeosphere

Science.gov (United States)

Trumbore, S.; Küsel, K.; Totsche, K. U.; Schwab, V.; Herrmann, M.; Nowak, M. E.; Gleixner, G.

2017-12-01

In the collaborative research project AquaDiva, we combine hydrogeochemical, metagemonic and biogeochemical tools to understand how the complex interactions between geologic setting and surface land use influence the function and biodiversity of the subsurface, especially ground water ecosystems. At the Hainich Critical Zone Exploratory in central Germany, we investigate soil and seepage waters in recharge areas and aquifers in a fractured limestone setting characterized by a dynamic water infiltration regime. Within the Exploratory, we have so far identified three distinct biogeochemical zones in which land use and lithologic differences combine to give rise to surprisingly different biotic communities and hydrogeochemical properties with different degrees of connection to the surface. Here we will focus on how we have combined carbon isotopic, organic biomarkers such as phospholipid fatty acids, and `omics' approaches to determine (i) how deep soil-borne microorganisms can be traced into the subsurface, and (ii) which energy sources sustain microbial life in oligotrophic limestone aquifers. With increasing travel distance to the surface, there is a decline in the abundance of microbes, with less than 5% of the taxa identified overlapping with those identified in the soils. Dissolved organic matter also is altered as it passes through soils, demonstrating an overall increase in molecular weight and a change in molecular makeup as well as radiocarbon content. Using the radiocarbon signature (corrected for the influence of carbonate dissolution), as a way to identify if organic C is being supplied recently by plants, atmosphere sources of energy for communities within the aquifer differ for the identified biogeochemical zones and include (i) dominance of inputs of fresh organic carbon from the surface feeding heterotrophy in oxygenic environments; (ii) CO2 fixation linked to nitrogen and sulfur cycling in anoxic environments and (iii) rock-derived organic matter

Surface chemical and electronic properties of In{sub 2}O{sub 3} and In{sub 2}O{sub 3-x} nanoparticles for ozone detection

Energy Technology Data Exchange (ETDEWEB)

Himmerlich, Marcel; Krischok, Stefan [Institut fuer Physik and Institut fuer Mikro- und Nanotechnologien, TU Ilmenau, PF 100565, 98684 Ilmenau (Germany); Wang, Chunyu; Cimalla, Volker; Ambacher, Oliver [Fraunhofer-Institut fuer Angewandte Festkoerperphysik, Tullastr. 72, 79108 Freiburg im Breisgau (Germany)

2012-07-01

The electrical properties of indium oxide nanoparticle films can be tuned by variation of growth temperature as well as rapid thermal annealing, UV-irradiation and ozone-induced oxidation. The high O{sub 3} sensitivity of indium oxide thin films is strongly linked to their structural and electronic properties. Especially, the alteration of the surface electron accumulation plays an important role in the change of the film resistivity upon O{sub 3} interaction and UV-induced regeneration. We analyse the changes of indium oxide surface properties with respect to varying crystallinity using AFM, XPS and UPS. Compared to stoichiometric In{sub 2}O{sub 3} thin films, indium oxide nanoparticles exhibit a high oxygen deficiency and hence a high defect density at the nanoparticle surface. After growth, these defects are saturated by hydrocarbons due to the incomplete decomposition of precursors during low temperature MOCVD. The defects and the changed stoichiometry have impact on the surface band alignment. Upon ozone-induced oxidation and UV photoreduction a reversible change in band bending, surface dipole and O adsorption density is found and will be discussed in context with electron transport characteristics and thermal properties.

Plasma-assisted cleaning of extreme UV optics

NARCIS (Netherlands)

Dolgov, Alexandr Alexeevich

2018-01-01

Plasma-assisted cleaning of extreme UV optics EUV-induced surface plasma chemistry of photo-active agents The next generation of photolithography, extreme ultraviolet (EUV) lithography, makes use of 13.5 nm radiation. The ionizing photon flux, and vacuum requirements create a challenging operating

UV-Absorption—The Primary Process in Photocatalysis and Some Practical Consequences

Directory of Open Access Journals (Sweden)

Terry A. Egerton

2014-11-01

Full Text Available TiO2 photochemistry studies generally address reactions of photogenerated charge-carriers at the oxide surface or the recombination reactions which control the proportion of charge carriers that reach the surface. By contrast, this review focuses on UV absorption, the first photochemical step in semiconductor photocatalysis. The influence of particle size on absorption and scattering of light by small TiO2 particles is summarized and the importance of considering, the particle size in the application, not the BET or X-ray line broadening size, is emphasized. Three different consequences of UV absorption are then considered. First, two commercially important systems, pigmented polymer films and paints, are used to show that TiO2 can protect from direct photochemical degradation. Then the effect of UV absorption on the measured photocatalytic degradation of aqueous solutions of organics is considered for two separate cases. Firstly, the consequences of UV absorption by TiO2 on the generation of hydroxyl radicals from H2O2 are considered in the context of the claimed synergy between H2O2 and TiO2. Secondly, the effect of altered UV absorption, caused by changed effective particle size of the catalyst, is demonstrated for photocatalysis of propan-2-ol oxidation and salicylic acid degradation.

Quality assessment of solar UV irradiance measured with array spectroradiometers

Science.gov (United States)

Egli, Luca; Gröbner, Julian; Hülsen, Gregor; Bachmann, Luciano; Blumthaler, Mario; Dubard, Jimmy; Khazova, Marina; Kift, Richard; Hoogendijk, Kees; Serrano, Antonio; Smedley, Andrew; Vilaplana, José-Manuel

2016-04-01

The reliable quantification of ultraviolet (UV) radiation at the earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers (ASRMs) are small, light, robust and cost-effective instruments, and are increasingly used for spectral irradiance measurements. Within the European EMRP ENV03 project "Solar UV", new devices, guidelines and characterization methods have been developed to improve solar UV measurements with ASRMs, and support to the end user community has been provided. In order to assess the quality of 14 end user ASRMs, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the blind intercomparison revealed that ASRMs, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema-weighted UV index - in particular at large solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available ASRMs within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range of solar zenith angles. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 and 400 nm under all atmospheric conditions.

UV/Vis and NIR Light-Responsive Spiropyran Self-Assembled Monolayers

NARCIS (Netherlands)

Ivashenko, Oleksii; Herpt, Jochem T. van; Feringa, Ben L.; Rudolf, Petra; Browne, Wesley R.

2013-01-01

Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SEAS), and X-ray photoelectron spectroscopies (XPS). The SAMs

UV Photofragmentation Dynamics of Protonated Cystine: Disulfide Bond Rupture.

Science.gov (United States)

Soorkia, Satchin; Dehon, Christophe; Kumar, S Sunil; Pedrazzani, Mélanie; Frantzen, Emilie; Lucas, Bruno; Barat, Michel; Fayeton, Jacqueline A; Jouvet, Christophe

2014-04-03

Disulfide bonds (S-S) play a central role in stabilizing the native structure of proteins against denaturation. Experimentally, identification of these linkages in peptide and protein structure characterization remains challenging. UV photodissociation (UVPD) can be a valuable tool in identifying disulfide linkages. Here, the S-S bond acts as a UV chromophore and absorption of one UV photon corresponds to a σ-σ* transition. We have investigated the photodissociation dynamics of protonated cystine, which is a dimer of two cysteines linked by a disulfide bridge, at 263 nm (4.7 eV) using a multicoincidence technique in which fragments coming from the same fragmentation event are detected. Two types of bond cleavages are observed corresponding to the disulfide (S-S) and adjacent C-S bond ruptures. We show that the S-S cleavage leads to three different fragment ions via three different fragmentation mechanisms. The UVPD results are compared to collision-induced dissociation (CID) and electron-induced dissociation (EID) studies.

Validation of OMI UV measurements against ground-based measurements at a station in Kampala, Uganda

Science.gov (United States)

Muyimbwa, Dennis; Dahlback, Arne; Stamnes, Jakob; Hamre, Børge; Frette, Øyvind; Ssenyonga, Taddeo; Chen, Yi-Chun

2015-04-01

We present solar ultraviolet (UV) irradiance data measured with a NILU-UV instrument at a ground site in Kampala (0.31°N, 32.58°E), Uganda for the period 2005-2014. The data were analyzed and compared with UV irradiances inferred from the Ozone Monitoring Instrument (OMI) for the same period. Kampala is located on the shores of lake Victoria, Africa's largest fresh water lake, which may influence the climate and weather conditions of the region. Also, there is an excessive use of worn cars, which may contribute to a high anthropogenic loading of absorbing aerosols. The OMI surface UV algorithm does not account for absorbing aerosols, which may lead to systematic overestimation of surface UV irradiances inferred from OMI satellite data. We retrieved UV index values from OMI UV irradiances and validated them against the ground-based UV index values obtained from NILU-UV measurements. The UV index values were found to follow a seasonal pattern similar to that of the clouds and the rainfall. OMI inferred UV index values were overestimated with a mean bias of about 28% under all-sky conditions, but the mean bias was reduced to about 8% under clear-sky conditions when only days with radiation modification factor (RMF) greater than 65% were considered. However, when days with RMF greater than 70, 75, and 80% were considered, OMI inferred UV index values were found to agree with the ground-based UV index values to within 5, 3, and 1%, respectively. In the validation we identified clouds/aerosols, which were present in 88% of the measurements, as the main cause of OMI inferred overestimation of the UV index.

Effects of UV radiation on freshwater metazooplankton

International Nuclear Information System (INIS)

Tartarotti, B.

1999-06-01

There is evidence that fluxes of solar ultraviolet-B radiation (UV-B, 290-320 nm) are increasing over wide parts of the earth's surface due to stratospheric ozone depletion. UV radiation (290-400 nm) can have damaging effects on biomolecules and cell components that are common to most living organisms. The aim of this thesis is to gain a more thorough understanding of the potential impacts of solar radiation on freshwater metazooplankton. To detect UV-vulnerability in zooplankton populations dominating the zooplankton community of two clear-water, high mountain lakes located one in the Austrian Alps and another in the Chilean Andes, the survival of two copepod species was studied. The organisms were exposed to a 10- to 100-fold increase in UV-B radiation compared to those levels found at their natural, maximum daytime distribution. Both species vertically migrate and are pigmented. UV-absorbing compounds with a maximum absorption at ∼334 nm were also detected. Cyclops abyssorum tatricus, a common cyclopoid copepod species of Alpine lakes, was highly resistant to UV-B radiation and no significant lethal effect was observed. The calanoid copepod Boeckella gracilipes, frequent in Andean lakes, had a mortality ∼5 times higher in the treatment receiving full sunlight than in the UV-B excluded treatment (3.2 %) only when exposed for 70 h. The resistance of B. gracilipes was higher than that reported in the literature for the same species suggesting the existence of intraspecific differences in UV sensitivity. Survival, fecundity and development of the zooplankton community of a clear-water, high elevation Andean lake (33 o S) were studied with mesocosms experiments after prolonged UV exposure (48 days). When exposed to full sunlight, the population of the cladoceran Chydorus sphaericus and the rotifer Lepadella ovalis were strongly inhibited by UV-B, whereas both species were resistant to UV-A radiation. Conversely, UV-B radiation had no effect on the survival of the

Bioactivating Silicon (100 Surfaces with Novel UV Grafting of Cyclopropylamine for Promotion of Cell Adhesion

Directory of Open Access Journals (Sweden)

Jing Yuan Ching

2018-05-01

Full Text Available In this report, utraviolent (UV photoionization of cyclopropylamine on silicon (100 hydride was employed to examine interfacing with three different epithelial cell types (MDA-MB 231, AGS and HEC1A. The cellular viability using this novel methodology had been quantified to evaluate the bioactivating potential of this ring-opening chemistry when compared to standardized controls (aminopropyltriethoxylamine, collagen and poly-L lysine. X-ray photospectroscopy (XPS and atomic force microscopy (AFM were used to characterize surface chemistry composition, while cell viability and confocal microscopy after 24 h of incubation were performed. Based on the results acquired from this novel ring-opening metastasis process, the promotion of cell adhesion and viability was found to be higher using this chemistry when compared to other conventional control groups, even for the collagen coating, without any observable issues of cytotoxicity.

Application of response surface methodology for optimization of natural organic matter degradation by UV/H2O2 advanced oxidation process.

Science.gov (United States)

Rezaee, Reza; Maleki, Afshin; Jafari, Ali; Mazloomi, Sajad; Zandsalimi, Yahya; Mahvi, Amir H

2014-01-01

In this research, the removal of natural organic matter from aqueous solutions using advanced oxidation processes (UV/H2O2) was evaluated. Therefore, the response surface methodology and Box-Behnken design matrix were employed to design the experiments and to determine the optimal conditions. The effects of various parameters such as initial concentration of H2O2 (100-180 mg/L), pH (3-11), time (10-30 min) and initial total organic carbon (TOC) concentration (4-10 mg/L) were studied. Analysis of variance (ANOVA), revealed a good agreement between experimental data and proposed quadratic polynomial model (R(2) = 0.98). Experimental results showed that with increasing H2O2 concentration, time and decreasing in initial TOC concentration, TOC removal efficiency was increased. Neutral and nearly acidic pH values also improved the TOC removal. Accordingly, the TOC removal efficiency of 78.02% in terms of the independent variables including H2O2 concentration (100 mg/L), pH (6.12), time (22.42 min) and initial TOC concentration (4 mg/L) were optimized. Further confirmation tests under optimal conditions showed a 76.50% of TOC removal and confirmed that the model is accordance with the experiments. In addition TOC removal for natural water based on response surface methodology optimum condition was 62.15%. This study showed that response surface methodology based on Box-Behnken method is a useful tool for optimizing the operating parameters for TOC removal using UV/H2O2 process.

Evaluation of UV-permeability and photo-oxidisability of organic ultraviolet radiation-absorbing coatings

Energy Technology Data Exchange (ETDEWEB)

Li, Neng; Chen, Yuhe, E-mail: yuhec@sina.com; Bao, Yongjie; Zhang, Zeqian; Wu, Zaixing; Chen, Zhangmin

2015-03-30

Highlights: • We investigate organic UV radiation-absorbing coatings for use on bamboo surfaces. • The size of glass exactly inserted into sample cell of UV-Vis spectrophotometer. • A model was made to predict UV absorption of coatings. • We examine carbonyl groups change of coatings after ageing. • Two formulations which could effectively protect coating were obtained. - Abstract: Enhancing the durability of the coatings used on bamboo products is essential for increasing their use in outdoor environments. In this study, we investigated organic UV radiation-absorbing coatings for use on bamboo surfaces. The degree of resistance of the coatings, which contained 2-(2-hydroxy-3-tert-butyl-5-methyl-phenyl)-5-chlorinated benzotriazole (BTZ-1), to UV radiation degradation was determined through spectroscopic analysis. The critical BTZ-1 loading amount was determined by analysing the spectroscopic data. Fourier transform infrared spectroscopy was used to elucidate the relationship between the degree of photooxidation of the coatings and their BTZ-1 concentration. The experimental results showed that the coatings provided a high degree of shielding from UV radiation. The critical loading amount was determined to be 1.82 ± 0.05 g BTZ-1/m{sup 2}. The coatings formed using the formulations that contained 3 and 5 wt% BTZ-1 exhibited the lowest degree of photooxidation after exposure to UV radiation.

UV-induced photochemical transformations of citrate-capped silver nanoparticle suspensions

International Nuclear Information System (INIS)

Gorham, Justin M.; MacCuspie, Robert I.; Klein, Kate L.; Fairbrother, D. Howard; Holbrook, R. David

2012-01-01

Due to the increasing use of silver nanoparticles (AgNPs) in consumer products, it is essential to understand how variables, such as light exposure, may change the physical and chemical characteristics of AgNP suspensions. To this end, the effect of 300 nm ultraviolet (UV) light on (20, 40, 60 and 80) nm citrate-capped AgNP suspensions has been investigated. As a consequence of irradiation, the initial yellow hue of the AgNP suspensions is transformed towards a near colorless solution due to the loss of the surface plasmon resonance (SPR) absorbance. The decrease in SPR absorbance followed a first-order decay process for all particle sizes with a rate constant that increased linearly with the AgNP specific surface area and non-linearly with light intensity. The rate of loss of the SPR absorbance decreased with increasing citrate concentration, suggesting a surface-mediated transformation. Absorbance, atomic force microscopy, and dynamic light scattering results all indicated that AgNP photolysis was accompanied by a diameter decrease and occasional aggregation. Furthermore, in situ transmission electron microscopy imaging using a specialized liquid cell also showed a decrease in the particle size and the formation of a core–shell structure in UV-exposed AgNPs. X-ray photoelectron spectroscopy analysis suggested that this shell consisted of oxidized silver. The SPR in UV-exposed AgNP suspensions could be regenerated by addition of a strong reducing agent (NaBH 4 ), supporting the idea that oxidized silver is present after photolysis. Evidence for UV-enhanced dissolution and the production of silver ions was obtained with the Donnan membrane technique. This study reveals that the physico-chemical properties of aqueous AgNP suspensions will change significantly upon exposure to UV light, with implications for environmental health and safety risk assessments.

Surface Map Traffic Intent Displays and Net-Centric Data-link Communications for NextGen

Science.gov (United States)

Shelton, Kevin J.; Prinzel, Lawrence J., III; Jones, Denise R.; Allamandola, Angela S.; Arthur, Jarvis J., III; Bailey, Randall E.

2009-01-01

By 2025, U.S. air traffic is predicted to increase three fold and may strain the current air traffic management system, which may not be able to accommodate this growth. In response to this challenge, a revolutionary new concept has been proposed for U.S. aviation operations, termed the Next Generation Air Transportation System or "NextGen". Many key capabilities are being identified to enable NextGen, including the use of data-link communications. Because NextGen represents a radically different approach to air traffic management and requires a dramatic shift in the tasks, roles, and responsibilities for the flight deck, there are numerous research issues and challenges that must be overcome to ensure a safe, sustainable air transportation system. Flight deck display and crew-vehicle interaction concepts are being developed that proactively investigate and overcome potential technology and safety barriers that might otherwise constrain the full realization of NextGen. The paper describes simulation research, conducted at National Aeronautics and Space Administration (NASA) Langley Research Center, examining data-link communications and traffic intent data during envisioned four-dimensional trajectory (4DT)-based and equivalent visual (EV) surface operations. Overall, the results suggest that controller pilot data-link communications (CPDLC) with the use of mandatory pilot read-back of all clearances significantly enhanced situation awareness for 4DT and EV surface operations. The depiction of graphical traffic state and intent information on the surface map display further enhanced off-nominal detection and pilot qualitative reports of safety and awareness.

Passive New UV Polarimeter for Remote Surface and Atmospheric Sensing, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Our imaging polarimeter concept makes available for the first time, the passive remote imagery of all four Stokes vector components at UV wavelengths shorter than...

Reactive electrospinning and biodegradation of cross-linked methacrylated polycarbonate nanofibers

Energy Technology Data Exchange (ETDEWEB)

Wu Ruizhi; Zhang Jianfeng; Fan Yuwei; Xu Xiaoming [Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Sciences Center, 1100 Florida Avenue, Box 137, New Orleans, LA 70119 (United States); Stoute, Diana; Lallier, Thomas, E-mail: xxu@lsuhsc.edu [Department of Cell Biology and Anatomy, Louisiana State University Health Science Center, 1100 Florida Avenue, Box 137, New Orleans, LA 70119 (United States)

2011-06-15

The objectives of this study were to fabricate cross-linked biodegradable polycarbonate nanofibers and to investigate their biodegradability by different enzymes. Poly(2,3-dihydroxycarbonate) was synthesized from naturally occurring l-tartaric acid. The hydroxyl groups on the functional polycarbonate were converted to methacrylate groups to enable the polymer to cross-link under UV irradiation. Smooth cross-linked methacrylated polycarbonate nanofibers (300-1800 nm) were fabricated by a reactive electrospinning process with in situ UV radiation from a mixed solution of linear methacrylated polycarbonate (MPC) and poly(ethylene oxide) (PEO) (MPC:PEO = 9:1) in methanol/chloroform (50/50). These cross-linked nanofibers have shown excellent solvent resistance and their solubility decreases with increasing degree of cross-linking. The thermal properties of linear and cross-linked polycarbonate nanofibers were investigated by differential scanning calorimetry and thermogravimetric analysis. The cross-linked polycarbonate nanofibers show no melting point below 200 {sup 0}C and their decomposition temperature increases with increasing cross-linking degree. Their biodegradation products by five different enzymes were analyzed using liquid chromatography-mass spectrometry (LC-MS). The biodegradability of the polycarbonate nanofibers decreases with increasing cross-linking degree. These nanofibers were found to support human fibroblast survival and to promote cell attachment. This study demonstrates that cross-linked biodegradable polycarbonate nanofibers with different chemical properties and biodegradability can be fabricated using the novel reactive electrospinning technology to meet the needs of different biomedical applications.

A method for UV-bonding in the fabrication of glass electrophoretic microchips.

Science.gov (United States)

Huang, Z; Sanders, J C; Dunsmor, C; Ahmadzadeh, H; Landers, J P

2001-10-01

This paper presents an approach for the development of methodologies amenable to simple and inexpensive microchip fabrication, potentially applicable to dissimilar materials bonding and chip integration. The method involves a UV-curable glue that can be used for glass microchip fabrication bonding at room temperature. This involves nothing more than fabrication of glue "guide channels" into the microchip architecture that upon exposure to the appropriate UV light source, bonds the etched plate and cover plate together. The microchip performance was verified by capillary zone electrophoresis (CZE) of small fluorescent molecules with no microchannel surface modification carried out, as well as with a DNA fragment separation following surface modification. The performance of these UV-bonded electrophoretic microchips indicates that this method may provide an alternative to high temperature bonding.

UV-killed Staphylococcus aureus enhances adhesion and differentiation of osteoblasts on bone-associated biomaterials.

Science.gov (United States)

Somayaji, Shankari N; Huet, Yvette M; Gruber, Helen E; Hudson, Michael C

2010-11-01

Titanium alloys (Ti) are the preferred material for orthopedic applications. However, very often, these metallic implants loosen over a long period and mandate revision surgery. For implant success, osteoblasts must adhere to the implant surface and deposit a mineralized extracellular matrix (ECM). Here, we utilized UV-killed Staphylococcus aureus as a novel osteoconductive coating for Ti surfaces. S. aureus expresses surface adhesins capable of binding to bone and biomaterials directly. Furthermore, interaction of S. aureus with osteoblasts activates growth factor-related pathways that potentiate osteogenesis. Although UV-killed S. aureus cells retain their bone-adhesive ability, they do not stimulate significant immune modulator expression. All of the abovementioned properties were utilized for a novel implant coating so as to promote osteoblast recruitment and subsequent cell functions on the bone-implant interface. In this study, osteoblast adhesion, proliferation, and mineralized ECM synthesis were measured on Ti surfaces coated with fibronectin with and without UV-killed bacteria. Osteoblast adhesion was enhanced on Ti alloy surfaces coated with bacteria compared to uncoated surfaces, while cell proliferation was sustained comparably on both surfaces. Osteoblast markers such as collagen, osteocalcin, alkaline phosphatase activity, and mineralized nodule formation were increased on Ti alloy coated with bacteria compared to uncoated surfaces.

Structure of DNA damaged by UV and psoralen

International Nuclear Information System (INIS)

Sung-hou Kim; Tomic, M.T.; Wemmer, D.E.; Pearlman, D.; Holbrook, S.

1988-01-01

The authors have used NMR methods to determine a three-dimensional model of an 8 base-pair DNA fragment cross-linked with psoralen. The duplex form of the self-complementary deoxyribonucleotide d-GGGTACCC, contains a psoralen cross-linkable site at the center of the duplex. The cross-link was formed by UV irradiation of a mixture of the purified DNA octamer and 4'-(aminomethyl)-4,5',8-trimethylpsoralen (AMT). Structural information was obtained using one and two-dimensional NMR techniques. Two-dimensional NOE experiments were used to assign the spectrum and estimate distances for many pairs of protons in the cross-linked DNA. Structural parameters obtained are qualitatively consistent with a previously proposed model for kinked and unwound cross-linked B-form DNA derived from crystallography and molecular modeling. The NMR derived model has a 53 degree bend into the major groove occuring primarily at the site of drug addition, and a 56 degree unwinding spanning the 8 base pair duplex. (author)

Facile synthesis of ceria nanoparticles by precipitation route for UV blockers

International Nuclear Information System (INIS)

Anupriya, K.; Vivek, E.; Subramanian, B.

2014-01-01

Highlights: • Homogenous precipitation was employed to prepare ceria nanoparticles. • An increase in the specific surface area was observed. • TEM showed particle sizes of 4 nm. • Material showed UV shielding effect. -- Abstract: Homogeneous ceria (CeO 2 ) nano particles of approximately 4 nm have been successfully synthesized via a simple precipitation route by employing the mixed solvent method. X-ray diffraction analysis revealed the precipitate particles to be of highly crystalline nature with face centered cubic structure along (1 1 1) (2 0 0) (2 2 0) (3 1 1) (4 0 0) (3 3 1) (4 2 2) (5 1 1) planes. Cerium oxide nanoparticles exhibits enhanced specific surface area of about 139.116 m 2 /g. The mono-dispersed spherical shape morphology of approximately 4 nm particles was confirmed using TEM analysis and its chemical composition by SEM–EDS analysis. Surface morphology reveals the smooth surface with an average roughness of 14.9 nm with the help of AFM. Raman studies show a characteristic peak at 464 cm −1 . The UV absorption edge was found at 314 nm i.e. In the Ultra Violet region suggesting that the material has a good absorption of UV light. Also, it shows an excellent transparency in the visible region

Facile synthesis of ceria nanoparticles by precipitation route for UV blockers

Energy Technology Data Exchange (ETDEWEB)

Anupriya, K.; Vivek, E.; Subramanian, B., E-mail: subramanianb3@gmail.com

2014-03-25

Highlights: • Homogenous precipitation was employed to prepare ceria nanoparticles. • An increase in the specific surface area was observed. • TEM showed particle sizes of 4 nm. • Material showed UV shielding effect. -- Abstract: Homogeneous ceria (CeO{sub 2}) nano particles of approximately 4 nm have been successfully synthesized via a simple precipitation route by employing the mixed solvent method. X-ray diffraction analysis revealed the precipitate particles to be of highly crystalline nature with face centered cubic structure along (1 1 1) (2 0 0) (2 2 0) (3 1 1) (4 0 0) (3 3 1) (4 2 2) (5 1 1) planes. Cerium oxide nanoparticles exhibits enhanced specific surface area of about 139.116 m{sup 2}/g. The mono-dispersed spherical shape morphology of approximately 4 nm particles was confirmed using TEM analysis and its chemical composition by SEM–EDS analysis. Surface morphology reveals the smooth surface with an average roughness of 14.9 nm with the help of AFM. Raman studies show a characteristic peak at 464 cm{sup −1}. The UV absorption edge was found at 314 nm i.e. In the Ultra Violet region suggesting that the material has a good absorption of UV light. Also, it shows an excellent transparency in the visible region.

The Effects of UV Light on the Chemical and Mechanical Properties of a Transparent Epoxy-Diamine System in the Presence of an Organic UV Absorber

Directory of Open Access Journals (Sweden)

Saeid Nikafshar

2017-02-01

Full Text Available Despite several excellent properties including low shrinkage, good chemical resistance, curable at low temperatures and the absence of byproducts or volatiles, epoxy resins are susceptible to ultra violet (UV damage and their durability is reduced substantially when exposed to outdoor environments. To overcome this drawback, UV absorbers have been usually used to decrease the rate of UV degradation. In this present study, the effects of UV light on the chemical, mechanical and physical properties of cured epoxy structure, as well as the effect of an organic UV absorber, Tinuvin 1130, on the epoxy properties were investigated. Chemical changes in a cured epoxy system as a result of the presence and absence of Tinuvin 1130 were determined using Fourier transform infrared spectroscopy (FT-IR analyses. The effect of Tinuvin 1130 on the surface morphology of the epoxy systems was also investigated by scanning electron microscopy (SEM imaging. Additionally, the glass transition temperatures (Tg before and during UV radiation were measured. After an 800 h UV radiation, mechanical test results revealed that the lack of the UV absorber can lead to a ~30% reduction in tensile strength. However, in the presence of Tinuvin 1130, the tensile strength was reduced only by ~11%. It was hypothesized that the use of Tinuvin 1130, as an organic UV absorber in the epoxy-amine system, could decrease the undesirable effects, arising from exposure to UV light.

UV-induced mitotic co-segregation of genetic markers in Candida albicans: Evidence for linkage

International Nuclear Information System (INIS)

Crandall, M.

1983-01-01

Parasexual genetic studies of the medically important yeast Candida albicans were performed using the method of UV-induced mitotic segregation. UV-irradiation of the Hoffmann-La Roche type culture of C. albicans yielded a limited spectrum of mutants at a relatively high fequency. This observation suggested natural heterozygosity. Canavanine-sensitive (CanS) segregants were induced at a frequency of 7.6 . 10 -3 . Double mutants that were both CanS and methionine (Met - ) auxotrophs were induced at a frequency of 7.4 . 10 -3 . The single Met - segregant class was missing indicating linkage. UV-induced CanS or Met - CanS segregants occurred occasionally in twin-sectored colonies. Analyses of the sectors as well as the observed and missing classes of segregants indicated that genes met and can are linked in the cis configuration. The proposed gene order is: centromere - met - can. Thus, it is concluded that the Hoffmann-La Roche strain of C. albicans is naturally heterozygous at two linked loci. These findings are consistent with diploidy. (orig.)

The effect of UV stars on the intergalactic medium. II

International Nuclear Information System (INIS)

Sonnanstine, A.E.; Hills, J.G.

1976-01-01

The effect of ionizing radiation from the UV stars (hot prewhite dwarfs) on the intergalactic medium (IGM) has been investigated. If the UV stars are powered only by gravitational contraction they radiate most of their energy at a typical surface temperature of 1.5 x 10 5 K which produces a very highly ionized IGM in which the elements carbon, nitrogen and oxygen are left with only one or two electrons. This result in these elements being very inefficient coolants. The gas is cooled principally by free-free emission and the collisional ionization of hydrogen and helium. For a typical UV star temperature of T=1.5 x 10 5 K, the temperature of the ionized gas in the IGM is Tsub(g)=1.2 x 10 5 K for a Hubble constant H 0 =75 kms -1 Mpc -1 and a hydrogen density nsub(H)=10 -6 cm -3 . Heating by cosmic rays and X-rays is insignificant in the IGM except perhaps in the H I clouds because when a hydrogen atom recombines in the IGM it is far more likely to be re-ionized by a UV-star photon than by either of the other two types of particles due to the greater space density of UV-star photons and their appreciably larger ionization cross sections. If the UV stars radiate a substantial fraction of their energy in a helium-burning stage in which they have surface temperatures of about 5 x 10 4 K, the temperature of the IGM could be lowered to about 5 x 10 4 K. (Auth.)

Cavity-mirror degradation in the deep-UV FEL

Energy Technology Data Exchange (ETDEWEB)

Yamada, K.; Yamazaki, T.; Sei, N. [Electrotechnical Lab., Ibaraki (Japan)] [and others

1995-12-31

It is known that the degradation of dielectric multilayer mirrors used in short wavelength free-electron lasers (FELs) is caused by the carbon contamination on the mirror surface and the defects inside the dielectrics. We reported last year that the degraded dielectric multilayer mirrors can be repaired with both surface treatment by RF-induced oxygen plasma and thermal annealing. However, such a mirror degradation is still one of the most critical issues in the deep ultraviolet (UV) FELs, because the fundamental undulator radiation resonating in the laser cavity, the intensity of which is much higher than that of higher harmonics, can be sufficiently energetic to cause the mirror degradation through photochemical reactions. We are investigating the mirror degradation mainly in the deep UV region down to 240 nm. The experimental results will be shown. The mirror degradation mechanism will be discussed.

UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

Directory of Open Access Journals (Sweden)

J. Para

2013-04-01

Full Text Available Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC, and optical characteristics including UV (ultraviolet radiation and PAR (photosynthetically active radiation diffuse attenuation (Kd, and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM as part of the MALINA field campaign (30 July to 27 August. Spectral absorption coefficients (aCDOM (350 nm (m−1 were significantly correlated to both diffuse attenuation coefficients (Kd in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1–C3 were identified by fluorescence excitation/emission matrix spectroscopy (EEMS and parallel factor (PARAFAC analysis. Our results showed an aquatic dissolved organic matter (DOM component (C1, probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2 in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

Science.gov (United States)

Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

2013-04-01

Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV (ultraviolet) radiation and PAR (photosynthetically active radiation) diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM) by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence excitation/emission matrix spectroscopy (EEMS) and parallel factor (PARAFAC) analysis. Our results showed an aquatic dissolved organic matter (DOM) component (C1), probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

Surface modification of TiO2 with g-C3N4 for enhanced UV and visible photocatalytic activity

International Nuclear Information System (INIS)

Lei, Juying; Chen, Ying; Shen, Fan; Wang, Lingzhi; Liu, Yongdi; Zhang, Jinlong

2015-01-01

Highlights: • g-C 3 N 4 /TiO 2 was prepared by a one-step preparation under mild conditions. • Photocatalysts showed excellent activity under both UV and visible light. • A neat surface modification process is proved, excluding influence of N doping. • Two photocatalytic mechanisms under different wavelengths are proposed. • A wide range of available wavelengths would greatly improve practicability of TiO 2 . - Abstract: g-C 3 N 4 modified TiO 2 composites were prepared through a simple calcination process of anatase and cyanamide. The as-prepared samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectrophotometry (DRS), fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermogravimetry differential thermal analysis (TG–DTA) and X-ray photoelectron spectroscopy (XPS), proving a successful modification of TiO 2 with g-C 3 N 4 . Photodegradation of acid orange 7 (AO7) was used to evaluate the photocatalytic activities of the composites, showing excellent activity of them under both visible and UV light. In addition, base treatment was then introduced to investigate the interaction between g-C 3 N 4 and TiO 2 . After removing the g-C 3 N 4 modified on TiO 2 by base, no nitrogen doping is found in TiO 2 lattice, demonstrating the g-C 3 N 4 was surface attached on TiO 2 and attributing all improvement of photocatalytic activity of g-C 3 N 4 /TiO 2 composite to the synergy between the two semiconductors

Combining covalent and noncovalent cross-linking: a novel terpolymer for two-step curing applications

NARCIS (Netherlands)

El-Ghayoury, A.; Hofmeier, H.; Ruiter, de B.; Schubert, U.S.

2003-01-01

A terpolymer of poly(butyl acrylate) bearing terpyridine as well as oxetane units was synthesized by free radical polymerization and characterized using NMR, UV-vis, and GPC. Subsequently, UV-vis experiments indicated clearly a noncovalent cross-linking of the terpyridine moieties by addition of

Effects of UV radiation on phytoplankton

Science.gov (United States)

Smith, Raymond C.; Cullen, John J.

1995-07-01

It is now widely documented that reduced ozone will result in increased levels of ultraviolet (UV) radiation, especially UV-B (280-320nm), incident at the surface of the earth [Watson, 1988; Anderson et al., 1991; Schoeberl and Hartmann, 1991; Frederick and Alberts, 1991; WMO, 1991; Madronich, 1993; Kerr and McElroy, 1993], and there is considerable and increasing evidence that these higher levels of UV-B radiation may be detrimental to various forms of marine life in the upper layers of the ocean. With respect to aquatic ecosystems, we also know that this biologically- damaging mid-ultraviolet radiation can penetrate to ecologically- significant depths in marine and freshwater systems [Jerlov, 1950; Lenoble, 1956; Smith and Baker, 1979; Smith and Baker, 1980; Smith and Baker, 1981; Kirk et al., 1994]. This knowledge, plus the dramatic decline in stratospheric ozone over the Antarctic continent each spring, now known to be caused by anthropogenically released chemicals [Solomon, 1990; Booth et al., 1994], has resulted in increased UV-environmental research and a number of summary reports. The United Nations Environmental Program (UNEP) has provided recent updates with respect to the effects of ozone depletion on aquatic ecosystems (Hader, Worrest, Kumar in UNEP 1989, 1991, Hader, Worrest, Kumar and Smith UNEP 1994) and the Scientific Committee on Problems of the Environment (SCOPE) has provided [SCOPE, 1992] a summary of the effects of increased UV radiation on biological systems. SCOPE has also reported [SCOPE, 1993] on the effects of increased UV on the biosphere. In addition, several books have recently been published reviewing various aspects of environmental UV photobiology [Young et al., 1993], UV effects on humans, animals and plants [Tevini, 1993], the biological effects of UV radiation in Antarctica [Weiler and Penhale, 1994], and UV research in freshwater ecosystems [Williamson and Zagarese, 1994]. Several other reviews are relevant [NAS, 1984; Caldwell

Diurnal changes in epidermal UV transmittance of plants in naturally high UV environments.

Science.gov (United States)

Barnes, Paul W; Flint, Stephan D; Slusser, James R; Gao, Wei; Ryel, Ronald J

2008-06-01

Studies were conducted on three herbaceous plant species growing in naturally high solar UV environments in the subalpine of Mauna Kea, Hawaii, USA, to determine if diurnal changes in epidermal UV transmittance (T(UV)) occur in these species, and to test whether manipulation of the solar radiation regime could alter these diurnal patterns. Additional field studies were conducted at Logan, Utah, USA, to determine if solar UV was causing diurnal T(UV) changes and to evaluate the relationship between diurnal changes in T(UV) and UV-absorbing pigments. Under clear skies, T(UV), as measured with a UV-A-pulse amplitude modulation fluorometer for leaves of Verbascum thapsus and Oenothera stricta growing in native soils and Vicia faba growing in pots, was highest at predawn and sunset and lowest at midday. These patterns in T(UV) closely tracked diurnal changes in solar radiation and were the result of correlated changes in fluorescence induced by UV-A and blue radiation but not photochemical efficiency (F(v)/F(m)) or initial fluorescence yield (F(o)). The magnitude of the midday reduction in T(UV) was greater for young leaves than for older leaves of Verbascum. Imposition of artificial shade eliminated the diurnal changes in T(UV) in Verbascum, but reduction in solar UV had no effect on diurnal T(UV) changes in Vicia. In Vicia, the diurnal changes in T(UV) occurred without detectable changes in the concentration of whole-leaf UV-absorbing compounds. Results suggest that plants actively control diurnal changes in UV shielding, and these changes occur in response to signals other than solar UV; however, the underlying mechanisms responsible for rapid changes in T(UV) remain unclear.

Self-generated covalent cross-links in the cell-surface adhesins of Gram-positive bacteria.

Science.gov (United States)

Baker, Edward N; Squire, Christopher J; Young, Paul G

2015-10-01

The ability of bacteria to adhere to other cells or to surfaces depends on long, thin adhesive structures that are anchored to their cell walls. These structures include extended protein oligomers known as pili and single, multi-domain polypeptides, mostly based on multiple tandem Ig-like domains. Recent structural studies have revealed the widespread presence of covalent cross-links, not previously seen within proteins, which stabilize these domains. The cross-links discovered so far are either isopeptide bonds that link lysine side chains to the side chains of asparagine or aspartic acid residues or ester bonds between threonine and glutamine side chains. These bonds appear to be formed by spontaneous intramolecular reactions as the proteins fold and are strategically placed so as to impart considerable mechanical strength. © 2015 Authors; published by Portland Press Limited.

Double transfer UV-curing nanoimprint lithography

International Nuclear Information System (INIS)

Shen, Yiming; Yao, Lei; Li, Zhiwei; Kou, Junlong; Cui, Yushuang; Bian, Jie; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng; Li, Wen-Di; Wu, Wei

2013-01-01

A challenge in the fabrication of nanostructures into non-planar substrates is to form a thin, uniform resist film on non-planar surfaces. This is critical to the fabrication of nanostructures via a lithographic technique due to the subsequent pattern transfer process. Here we report a new double transfer UV-curing nanoimprint technique that can create a nanopatterned thin film with a uniform residual layer not only on flat substrates but also on highly curved surfaces. Surface relief gratings with pitches down to 200 nm are successfully imprinted on the cylindrical surface of optical fibers, and further transferred into a SiO 2 matrix using reactive ion etching (RIE), demonstrating that our technique is applicable for fabricating high-resolution nanostructures on non-planar substrates. (paper)

Fabrication of surface micro- and nanostructures for superhydrophobic surfaces in electric and electronic applications

Science.gov (United States)

Xiu, Yonghao

our understanding of the roughness effect on superhydrophobicity (both contact angle and hysteresis), structured surfaces from polybutadiene, polyurethane, silica, and Si etc. were successfully prepared. For engineering applications of superhydrophobic surfaces, stability issues regarding UV, mechanical robustness and humid environment need to be investigated. Among these factors, UV stability is the first one to be studied. However, most polymer surfaces we prepared failed the purpose. Silica surfaces with excellent UV stability were prepared. This method consists of preparation of rough silica surfaces, thermal treatment and the following surface hydrophobization by fluoroalkyl silane treatment. Fluoroalkyl groups are UV stable and the underlying species are silica which is also UV stable (UV transparent). UV stability on the surface currently is 5,500 h according the standard test method of ASTM D 4329. No degradation on surface superhydrophobicity was observed. New methods for preparing superhydrophobic and transparent silica surfaces were investigated using urea-choline chloride eutectic liquid to generate fine roughness and reduce the cost for preparation of surface structures. Another possible application for self-cleaning in photovoltaic panels was investigated on Si surfaces by construction of the two-scale rough structures followed by fluoroalkyl silane treatment. Metal (Au) assisted etching was employed to fabricate nanostructures on micrometer pyramid surfaces. The light reflection on the prepared surfaces was investigated. After surface texturing using KOH etching for micrometer pyramids and the following nanostructure using metal assisted etching, surface light reflection reduced to a minimum value which shows that this surface texturing technique is highly promising for improving the photovoltaic efficiency while imparting photovoltaics the self-cleaning feature. This surface is also expected to be UV stable due to the same fluoroalkyl silane used

Two DD-carboxypeptidases from Mycobacterium smegmatis affect cell surface properties through regulation of peptidoglycan cross-linking and glycopeptidolipids.

Science.gov (United States)

Pandey, Satya Deo; Pal, Shilpa; Kumar N, Ganesh; Bansal, Ankita; Mallick, Sathi; Ghosh, Anindya S

2018-05-07

During the peptidoglycan (PG) maturation of mycobacteria, the glycan strands are interlinked by both 3-3 (between two meso-DAP) and 4-3 cross-links (between D-ala and meso-DAP), though there is a predominance (60-80%) of 3-3 cross-links. The DD-CPases act on pentapeptides to generate tetrapeptides that are used by LD-transpeptidases as substrates to form 3-3 cross-links. Therefore, DD-CPases play a crucial role in mycobacterial PG cross-link formation. However, the physiology of DD-CPases in mycobacteria is relatively unexplored. Here, we deleted two DD-CPase genes, msmeg_2433 , and msmeg_2432 , both individually and in combination, from Mycobacterium smegmatis mc 2 155. Though the single DD-CPase deletions had no significant impact on the mycobacterial physiology, many interesting functional alterations were observed in the double deletion mutant, viz. , a predominance in PG cross-link formation was shifted from 3-3 cross-links to 4-3, cell surface glycopeptidolipid (GPL) expression was reduced and susceptibility towards β-lactams and anti-tubercular agents was enhanced. Moreover, the existence of the double mutant within murine macrophages was better as compared to the parent. Interestingly, the complementation with any one of the DD-CPase genes could restore the wild-type phenotype. In a nutshell, we infer that the altered ratio of 4-3: 3-3 PG cross-links might have influenced the expression of surface GPLs, colony morphology, biofilm formation,, drug susceptibility and subsistence of the cells within macrophages. Importance The glycan strands in mycobacterial peptidoglycan (PG) are interlinked by both 3-3 and 4-3 cross-links. The DD-CPases generate tetrapeptides by acting on the pentapeptides, and LD-transpeptidases use tetrapeptides as substrates to form 3-3 cross-links. Here, we showed that simultaneous deletions of two DD-CPases alter the nature of PG cross-linking from 3-3 cross-links to 4-3 cross-links. The deletions subsequently decrease the expression

Photoinduced hydrophobic surface of graphene oxide thin films

International Nuclear Information System (INIS)

Zhang Xiaoyan; Song Peng; Cui Xiaoli

2012-01-01

Graphene oxide (GO) thin films were deposited on transparent conducting oxide substrates and glass slides by spin coating method at room temperature. The wettability of GO thin films before and after ultraviolet (UV) irradiation was characterized with water contact angles, which increased from 27.3° to 57.6° after 3 h of irradiation, indicating a photo-induced hydrophobic surface. The UV–vis absorption spectra, Raman spectroscopy, X-ray photoelectron spectroscopy, and conductivity measurements of GO films before and after UV irradiation were taken to study the mechanism of photoinduced hydrophobic surface of GO thin films. It is demonstrated that the photoinduced hydrophobic surface is ascribed to the elimination of oxygen-containing functional groups on GO molecules. This work provides a simple strategy to control the wettability properties of GO thin films by UV irradiation. - Highlights: ► Photoinduced hydrophobic surface of graphene oxide thin films has been demonstrated. ► Elimination of oxygen-containing functional groups in graphene oxide achieved by UV irradiation. ► We provide novel strategy to control surface wettability of GO thin films by UV irradiation.

A fast determination of nitrate in rain and surface waters by means of UV spectrophotometry

International Nuclear Information System (INIS)

Slanina, J.; Lingerak, W.A.; Bergman, L.

1976-01-01

Organic substances are the main interference in the direct U.V. spectrophotometric determination of nitrate at 210 nm. An active carbon filter (Filopur) is therefore proposed which adsorbs all organic interferences. With this filter the U.V. spectrophotometric method gives the same results as the Na-salicylate method. The reproducibility is generally better than 5%. One determination takes 50 s. (orig.) [de

UV-C irradiation disrupts platelet surface disulfide bonds and activates the platelet integrin alphaIIbbeta3

NARCIS (Netherlands)

Verhaar, Robin; Dekkers, David W. C.; de Cuyper, Iris M.; Ginsberg, Mark H.; de Korte, Dirk; Verhoeven, Arthur J.

2008-01-01

UV-C irradiation has been shown to be effective for pathogen reduction in platelet concentrates, but preliminary work indicated that UV-C irradiation of platelets can induce platelet aggregation. In this study, the mechanism underlying this phenomenon was investigated. Irradiation of platelets with

Functionalization of Cellulose Fibres with Oxygen Plasma and ZnO Nanoparticles for Achieving UV Protective Properties

Directory of Open Access Journals (Sweden)

Katja Jazbec

2015-01-01

Full Text Available Low-pressure oxygen plasma created by an electrodeless radiofrequency (RF discharge was applied to modify the properties of cellulosic fibrous polymer (cotton in order to improve adsorption properties towards zinc oxide (ZnO nanoparticles and to achieve excellent ultraviolet (UV protective properties of cotton fabric. The chemical and physical surface modifications of plasma-treated cotton fabric were examined by X-ray photoelectron spectroscopy (XPS and scanning electron microscopy (SEM. The mechanical properties of plasma-treated samples were evaluated, measuring strength and elongation of the fabrics. The quantity of zinc on the ZnO-functionalized cotton samples was determined using inductively coupled plasma mass spectrometry (ICP-MS and the effectiveness of plasma treatment for UV protective properties of cotton fabrics was evaluated using UV-VIS spectrometry, measuring the UV protection factor (UPF. The results indicated that longer plasma treatment times cause higher concentration of oxygen functional groups on the surface of fibres and higher surface roughness of fibres. These two conditions are crucial in increasing the content of ZnO nanoparticles on the fibres, providing excellent UV protective properties of treated cotton, with UPF factor up to 65.93.

Development of UV-curable liquid for in-liquid fluorescence alignment in ultraviolet nanoimprint lithography

Science.gov (United States)

Ochiai, Kento; Kikuchi, Eri; Ishito, Yota; Kumagai, Mari; Nakamura, Takahiro; Nakagawa, Masaru

2018-06-01

We studied a fluorescent UV-curable resin suitable for fluorescence alignment in UV nanoimprinting. The addition of a cationic fluorescent dye caused radical photopolymerization of a UV-curable resin by exposure to visible excitation light for fluorescence microscope observation. The microscope observation of a resin film prepared by pressing resin droplets on a silica substrate with a fluorinated silica superstrate revealed that the cationic dye molecules were preferably adsorbed onto the silica surface. It was indicated that the dye molecules concentrated on the silica surface may cause the photocuring. A nonionic fluorescent dye was selected owing to its low polar symmetrical structure and its solubility parameter close to monomers. The fluorescent UV-curable resin with the nonionic dye showed uncured stability to exposure to visible excitation light for 30 min with a light intensity of 8.5 mW cm‑2 detected at 530 nm.

Theoretical model for the UV disinfection system in the operating ward of PZU 'Filip Vtori'

International Nuclear Information System (INIS)

Ilkov, Marjan

2010-01-01

Here we investigate the theoretical modeling of an UV disinfection system for the operating ward in PZU 'FILIP VTORI'. As nocosomial infections pose a serious threat to patients everywhere in the world, here the disinfection of the air and the surfaces is modeled and discussed. The surfaces are disinfected with direct illumination of open UV after hours system, UV curtains, overhead disinfection, floor disinfection and disinfection of the incoming air through the ventilation/air-condition system. From the results it can be seen that the concentrations of bacteria, fungi and viruses drop significantly which in turn should give a significant drop in a number of hospital acquired infections.(Author)

Effects of prenatal exposure to surface-coated nanosized titanium dioxide (UV-Titan). A study in mice

DEFF Research Database (Denmark)

Hougaard, Karin S.; Jackson, Petra; Jensen, Keld A.

2010-01-01

to a nanoparticulate UV-filter (UV-titan L181). Methods: Time-mated mice (C57BL/6BomTac) were exposed by inhalation 1h/day to 42 mg/m(3) aerosolized powder (1.7.10(6) n/cm(3); peak-size: 97 nm) on gestation days 8-18. Endpoints included: maternal lung inflammation; gestational and litter parameters; offspring...... the central zone of the open field and exposed female offspring displayed enhanced prepulse inhibition. Cognitive function was unaffected (Morris water maze test). Conclusion: Inhalation exposure to nano-sized UV Titan dusts induced long term lung inflammation in time-mated adult female mice. Gestationally...

Multispectral UV Imaging for Determination of the Tablet Coating Thickness.

Science.gov (United States)

Novikova, Anna; Carstensen, Jens M; Zeitler, J Axel; Rades, Thomas; Leopold, Claudia S

2017-06-01

The applicability of off-line multispectral UV imaging in combination with multivariate data analysis was investigated to determine the coating thickness and its distribution on the tablet surface during lab-scale coating. The UV imaging results were compared with the weight gain measured for each individual tablet and the corresponding coating thickness and its distribution measured by terahertz pulsed imaging (TPI). Three different tablet formulations were investigated, 2 of which contained UV-active tablet cores. Three coating formulations were applied: Aquacoat® ECD (a mainly translucent coating) and Eudragit® NE (a turbid coating containing solid particles). It was shown that UV imaging is a fast and nondestructive method to predict individual tablet weight gain as well as coating thickness. The coating thickness distribution profiles determined by UV imaging correlated to the results of the TPI measurements. UV imaging appears to hold a significant potential as a process analytical technology tool for determination of the tablet coating thickness and its distribution resulting from its high measurement speed, high molar absorptivity, and a high scattering coefficient, in addition to relatively low costs. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

The Role of Limbal Epithelial Stem Cells in Regulating Corneal (Lymphangiogenic Privilege and the Micromilieu of the Limbal Niche following UV Exposure

Directory of Open Access Journals (Sweden)

M. Notara

2018-01-01

Full Text Available The cornea is a clear structure, void of blood, and lymphatic vessels, functioning as our window to the world. Limbal epithelial stem cells, occupying the area between avascular cornea and vascularized conjunctiva, have been implicated in tissue border maintenance, preventing conjunctivalisation and propagation of blood and lymphatic vessels into the cornea. Defects in limbal epithelial stem cells are linked to corneal neovascularisation, including lymphangiogenesis, chronic inflammation, conjunctivalisation, epithelial abnormalities including the presence of goblet cells, breaks in Bowman’s membrane, persistent epithelial defects and ulceration, ocular surface squamous neoplasia, lipid keratopathy, pain, discomfort, and compromised vision. It has been postulated that pterygium is an example of focal limbal deficiency. Previous reports showing changes occurring in limbal epithelium during pterygium pathogenesis suggest that there is a link to stem cell damage. In this light, pterygium can serve as a model disease of UV-induced stem cell damage also characterised by corneal blood and lymphangiogenesis. This review focuses on the role of corneal and limbal epithelial cells and the stem cell niche in maintaining corneal avascularity and corneal immune privilege and how this may be deregulated following UV exposure. We present an overview of the PUBMED literature in the field as well as recent work from our laboratories.

An evaluation of the infection control potential of a UV clinical podiatry unit.

Science.gov (United States)

Humphreys, Paul N; Davies, Chris S; Rout, Simon

2014-02-28

Infection control is a key issue in podiatry as it is in all forms of clinical practice. Airborne contamination may be particularly important in podiatry due to the generation of particulates during treatment. Consequently, technologies that prevent contamination in podiatry settings may have a useful role. The aims of this investigation were twofold, firstly to determine the ability of a UV cabinet to protect instruments from airborne contamination and secondly to determine its ability to remove microbes from contaminated surfaces and instruments. A UV instrument cabinet was installed in a University podiatry suite. Impact samplers and standard microbiological techniques were used to determine the nature and extent of microbial airborne contamination. Sterile filters were used to determine the ability of the UV cabinet to protect exposed surfaces. Artificially contaminated instruments were used to determine the ability of the cabinet to remove microbial contamination. Airborne bacterial contamination was dominated by Gram positive cocci including Staphylococcus aureus. Airborne fungal levels were much lower than those observed for bacteria. The UV cabinet significantly reduced (p podiatry settings due to the presence of S. aureus. The use of a UV instrument cabinet can reduce the risk of contamination by airborne microbes. The UV cabinet tested was unable to decontaminate instruments and as such could pose an infection risk if misused.

The role of DNA-protein interaction in the UV damage of T7 bacteriophage at high fluences

International Nuclear Information System (INIS)

Fekete, A.; Ronto, G.

1980-01-01

The influence of higher fluences (0.5-10 kJm -2 ) and that of phage protein coat on the UV (lambda = 254 nm) damage of T7 DNA were studied by UV difference spectroscopy. Beside the pyrimidine dimers and adducts produced also in isolated DNA in the case of intact phages and fluences exceeding 0.5 kJ m -2 other photoproducts, probably DNA-protein cross-links were identified as well. Phages deprived of their protein coat by a thermal treatment show similar UV damage to that of isolated DNA. (author)

UV hazard on Italian Apennines under different shading and ground cover conditions during peak tourist seasons of the year.

Science.gov (United States)

Grifoni, Daniele; Carreras, Giulia; Sabatini, Francesco; Zipoli, Gaetano

2006-12-01

In solar UV irradiance monitoring and forecasting services UV information is generally expressed in terms of its effect on erythema and referred to horizontal surface. In this work we define the UV radiative regime, in terms of biologically effective UV irradiance (UVBE) for skin and eye, under full sun and shaded conditions, over a mountainous tourist area of central Italy by means of two all-day measurements (summer and early spring) with different ground albedo (grass and snow cover respectively). UV irradiance was monitored on tilted surfaces (the most frequent for people standing and walking). Results show the significant contribution of ground albedo and sun position in determining the incident UVBE irradiance. On early spring days the UVBE irradiance measured on horizontal surface was much lower than on tilted ones; the opposite condition was observed in summer. The highest UVBE irradiance values, in particular conditions of sun elevation and ground cover, were reached in periods different from the summer both in full sun and shaded condition.

Growth and defense in deciduous trees and shrubs under UV-B

International Nuclear Information System (INIS)

Julkunen-Tiitto, Riitta; Haeggman, Hely; Aphalo, Pedro J.; Lavola, Anu; Tegelberg, Riitta; Veteli, Timo

2005-01-01

Reflection by waxy or resinous surface structures and hairs, repair reactions of biomolecules and induction of different sheltering components provide the means of plant protection from harmful solar UV-B radiation. Secondary products, especially flavonoids and phenolic acids as defense components are also important in plant tolerance to UV-B, fulfilling the dual role as screens that reduce UV-B penetration in plant tissues, and as antioxidants protecting from damage by reactive oxidant species. Plants are sensitive to UV-B radiation, and this sensitivity can be even more clone-specific than species-specific. The results available in the literature for deciduous trees and shrubs indicate that UV-B radiation may affect several directions in the interaction of woody species with biotic (herbivores) and abiotic (CO 2 and nutrition) factors depending on the specific interaction in question. These multilevel interactions should have moderate ecological significance via the overall changed performance of woody species and shrubs. - The growth performance of deciduous trees and shrubs under UV-B irradiation is constrained by multilevel interactions with many abiotic and biotic factors

Microbial UV fluence-response assessment using a novel UV-LED collimated beam system.

Science.gov (United States)

Bowker, Colleen; Sain, Amanda; Shatalov, Max; Ducoste, Joel

2011-02-01

A research study has been performed to determine the ultraviolet (UV) fluence-response of several target non-pathogenic microorganisms to UV light emitting diodes (UV-LEDs) by performing collimated beam tests. UV-LEDs do not contain toxic mercury, offer design flexibility due to their small size, and have a longer operational life than mercury lamps. Comsol Multiphysics was utilized to create an optimal UV-LED collimated beam design based on number and spacing of UV-LEDs and distance of the sample from the light source while minimizing the overall cost. The optimized UV-LED collimated beam apparatus and a low-pressure mercury lamp collimated beam apparatus were used to determine the UV fluence-response of three surrogate microorganisms (Escherichia coli, MS-2, T7) to 255 nm UV-LEDs, 275 nm UV-LEDs, and 254 nm low-pressure mercury lamps. Irradiation by low-pressure mercury lamps produced greater E. coli and MS-2 inactivation than 255 nm and 275 nm UV-LEDs and similar T7 inactivation to irradiation by 275 nm UV-LEDs. The 275 nm UV-LEDs produced more efficient T7 and E. coli inactivation than 255 nm UV-LEDs while both 255 nm and 275 nm UV-LEDs produced comparable microbial inactivation for MS-2. Differences may have been caused by a departure from the time-dose reciprocity law due to microbial repair mechanisms. Copyright © 2010 Elsevier Ltd. All rights reserved.

Surface functionalization by fine ultraviolet-patterning of nanometer-thick liquid lubricant films

International Nuclear Information System (INIS)

Lu, Renguo; Zhang, Hedong; Komada, Suguru; Mitsuya, Yasunaga; Fukuzawa, Kenji; Itoh, Shintaro

2014-01-01

Highlights: • We present fine UV-patterning of nm-thick liquid films for surface functionalization. • The patterned films exhibit both a morphological pattern and a functional pattern of different surface properties. • The finest pattern linewidth was 0.5 μm. • Fine patterning is crucial for improving surface and tribological properties. - Abstract: For micro/nanoscale devices, surface functionalization is essential to achieve function and performance superior to those that originate from the inherent bulk material properties. As a method of surface functionalization, we dip-coated nanometer-thick liquid lubricant films onto solid surfaces and then patterned the lubricant films with ultraviolet (UV) irradiation through a photomask. Surface topography, adhesion, and friction measurements demonstrated that the patterned films feature a concave–convex thickness distribution with thicker lubricant in the irradiated regions and a functional distribution with lower adhesion and friction in the irradiated convex regions. The pattern linewidth ranged from 100 to as fine as 0.5 μm. The surface functionalization effect of UV-patterning was investigated by measuring the water contact angles, surface energies, friction forces, and depletion of the patterned, as-dipped, and full UV-irradiated lubricant films. The full UV-irradiated lubricant film was hydrophobic with a water contact angle of 102.1°, and had lower surface energy, friction, and depletion than the as-dipped film, which was hydrophilic with a water contact angle of 80.7°. This demonstrates that UV irradiation substantially improves the surface and tribological properties of the nanometer-thick liquid lubricant films. The UV-patterned lubricant films exhibited superior surface and tribological properties than the as-dipped film. The water contact angle increased and the surface energy, friction, and depletion decreased as the pattern linewidth decreased. In particular, the 0.5-μm patterned lubricant

Isolation of uv-sensitive variants of CHO-Kl by nylon cloth replicaplating

International Nuclear Information System (INIS)

Stamato, T.D.; Waldren, C.A.

1977-01-01

Techniques are described which permit the identification and isolation of uv-sensitive variants from mutagenized populations of Chinese hamster ovary (CHO) cells. Identification is based on the observation that within two days after receiving a dose of approximately 240 ergs/mm 2 of uv irradiation, most of the cells in a colony of CHO detach from the surface of a plastic tissue culture dish. At a lower dose of uv, which does not kill or detach a significant number of parental cells, uv-sensitive colonies are killed and become detached. Thus a clear plaque is produced in a lawn of unirradiated parental cells, marking the site occupied by a sensitive colony. Live cells from such sensitive colonies have been recovered from a nylon cloth replica prepared prior to irradiation and characterized. One uv-sensitive variant (CHO-UV-1) is indistinguishable from parental cells in x-ray resistance, chromosome number, generation time, and duration of the phases of the cell cycle

UV stabilization of wood by nano metal oxides dispersed in propylene glycol.

Science.gov (United States)

Nair, Sreeja; Nagarajappa, Giridhar B; Pandey, Krishna K

2018-06-01

Nanoparticles of some of the metal oxides are known to have high UV protective efficiency. The UV filtering efficiency of nanoparticles invariably depends on their size and stability in the dispersion. In the present work, a stable dispersion of nanoparticles of three metal oxides, zinc oxide (ZnO), cerium oxide (CeO 2 ) and titanium dioxide (TiO 2 ), was prepared in propylene glycol (PG) using ultrasonication. The method is easy and useful as no additional surfactant or dispersant is needed. The particle size and its distribution was confirmed by Scanning Electron Microscopy and Dynamic Light Scattering. The stability of dispersion was assessed by UV-visible absorption spectroscopy. The UV stability of wood surfaces of Wrightia tinctoria coated with nanodispersions of ZnO, CeO 2 and TiO 2 was evaluated under laboratory conditions in an accelerated weathering tester. Changes in the colour and FTIR spectra of exposed specimens were measured periodically. Rapid colour darkening (yellowing) was observed in uncoated and PG coated specimens. In contrast, nanodispersion coated specimens prevented photo-yellowing considerably with significant reduction in colour changes examined by CIE L*, a*, b* and ΔE*. Increase in concentration of nanoparticles in the dispersion imparted higher resistance to UV induced degradation. However, increased concentration of nanoparticles reduced the transparency of the coating. FTIR analysis indicated rapid degradation of lignin in uncoated and PG coated specimens due to UV exposure. Coating of wood surfaces with nanodispersions restricted lignin degradation. The study also demonstrates the potential of propylene glycol as a dispersant for developing stable and efficient UV protective nanodispersions for wood coating. Copyright © 2018 Elsevier B.V. All rights reserved.

Applications of high order harmonic radiation to UVX-solids interaction: high excitation density in electronic relaxation dynamics and surface damaging

International Nuclear Information System (INIS)

De Grazia, M.

2007-12-01

The new sources of radiation in the extreme-UV (X-UV: 10-100 nm), which deliver spatially coherent, ultra-short and intense pulses, allow studying high flux processes and ultra-fast dynamics in various domains. The thesis work presents two applications of the high-order laser harmonics (HH) to solid state physics. In Part I, we describe the optimization of the harmonic for studies of X-UV/solids interaction. In Part II, we investigate effects of high excitation density in the dynamics of electron relaxation in dielectric scintillator crystals - tungstates and fluorides, using time-resolved luminescence spectroscopy. Quenching of luminescence at short time gives evidence of the competition between radiative and non-radiative recombination of self-trapped excitons (STE). The non-radiative channel is identified to mutual interaction of STE at high excitation density. In Part III, we study the X-UV induced damage mechanism in various materials, either conductor (amorphous carbon) or insulators (organic polymers, e.g., PMMA). In PMMA-Plexiglas, in the desorption regime (0.2 mJ/cm 2 , i.e., below damage threshold), the surface modifications reflect X-UV induced photochemical processes that are tentatively identified, as a function of dose: at low dose, polymer chain scission followed by the blow-up of the volatile, low-molecular fragments leads to crater formation; at high dose, cross-linking in the near-surface layer of remaining material leads to surface hardening. These promising results have great perspectives considering the performances already attained and planned in the next future in the development of the harmonic sources. (author)

A Survey of the Potential Effects of Increasing UV-B Radiation on the Biosphere. Revision

National Research Council Canada - National Science Library

Martin, L

1998-01-01

..., and an increase in UV-B radiation at the surface of the Earth. An increase in UV-B on average would increase the incidence rate of non-melanoma skin cancer worldwide, with an unproved but likely increase in melanoma skin cancer...

ZnO UV photodetector with controllable quality factor and photosensitivity

Directory of Open Access Journals (Sweden)

L. C. Campos

2013-02-01

Full Text Available ZnO nanowires have an enormous potential for applications as ultra-violet (UV photodetectors. Their mechanism of photocurrent generation is intimately related with the presence of surface states where considerable efforts, such as surface chemical modifications, have been pursued to improve their photodetection capabilities. In this work, we report a step further in this direction demonstrating that the relative photosensitivity and quality factor (Q factor of the photodetector are entirely tunable by an applied gate voltage. This mechanism enables UV photodetection selectivity ranging from wavelengths from tens of nanometers (full width at half maximum - FWHM down to a narrow detection of 3 nm. Such control paves the way for novel applications, especially related to the detection of elements that have very sharp luminescence.

Maternal inhalation of surface-coated nanosized titanium dioxide (UV-Titan) in C57BL/6 mice

DEFF Research Database (Denmark)

Jackson, Petra; Halappanavar, Sabina; Hougaard, Karin Sorig

2013-01-01

We investigated effects of maternal pulmonary exposure to titanium dioxide (UV-Titan) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were inhalation exposed (1 h/day to 42 mg UV-Titan/m(3) aerosolised powder or filtered air) during gestation days (GDs) 8-18. We evaluated DNA...... strand breaks using the comet assay in bronchoalveolar lavage (BAL) cells and livers of the time-mated mice (5 and 26-27 days after inhalation exposure), and in livers of the offspring (post-natal days (PND) 2 and 22). We also analysed hepatic gene expression in newborns using DNA microarrays. UV-Titan...

Genotoxicity testing of samples generated during UV/H2O2 treatment of surface water for the production of drinking water using the Ames test in vitro and the Comet assay and the SCE test in vivo

NARCIS (Netherlands)

Penders, E.J.M.; Martijn, A.J.; Spenkelink, A.; Alink, G.M.; Rietjens, I.; Hoogenboezem, W.

2012-01-01

UV/H2O2 treatment can be part of the process converting surface water to drinking water, but would pose a potential problem when resulting in genotoxicity. This study investigates the genotoxicity of samples collected from the water treatment plant Andijk, applying UV/H2O2 treatment with an

Specific behavior of the p-aminothiophenol--silver sol system in their Ultra-Violet-Visible (UV-Visible) and Surface Enhanced Raman (SERS) spectra.

Science.gov (United States)

Firkala, Tamás; Tálas, Emília; Mihály, Judith; Imre, Tímea; Kristyán, Sándor

2013-11-15

The UV-Visible and Surface Enhanced Raman Spectroscopy (SERS) behavior of silver sol (a typical SERS agent) were studied in the presence of different bifunctional thiols such as p-aminothiophenol, p-mercaptobenzoic acid, p-nitrothiophenol, p-aminothiophenol hydrochloride, and 2-mercaptoethylamine hydrochloride in diluted aqueous solution. Our results confirm that the p-aminothiophenol induced aggregation of citrate stabilized silver colloid originates from its electrostatic nature, as well as the azo-bridge formation cannot be the reason of the observed time dependent UV-Visible spectra. Based on our parallel SERS and electrospray ionization mass spectrometry measurements, we have concluded that certain amount of oxidized form of the probe molecule has to be present for the so-called b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Our findings seem to support the idea that the azo-bridge formation is responsible for the b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Copyright © 2013 Elsevier Inc. All rights reserved.

Discharge of viscous UV-curable resin droplets by screen printing for UV nanoimprint lithography

Science.gov (United States)

Tanabe, Akira; Uehara, Takuya; Nagase, Kazuro; Ikedo, Hiroaki; Hiroshiba, Nobuya; Nakamura, Takahiro; Nakagawa, Masaru

2016-06-01

We demonstrated a coating method of screen printing for discharging droplets of a high-viscosity resin on a substrate for ultraviolet (UV) nanoimprint lithography (NIL). Compared with a spin-coated resin film on a silicon substrate, discharged resin droplets on a silicon substrate were effective in terms of the uniformity of residual layer thickness (RLT) in contact with a mold with various pattern densities. Fluorescence microscope observations with a fluorescent-dye-containing UV-curable resin enabled the evaluation of the shapes of resin droplets discharged on a substrate surface. Widely used screen mesh plates composed of a stainless mesh covered with a patterned emulsion film caused defects of undischarged parts, whereas defects-free resin droplets with a narrow size distribution were discharged by mesh-free plates prepared with laser ablation. The pitch-to-diameter ratio in the configuration of 10-µm-diameter holes needs to be larger than 2.5 times for printing a resin having a viscosity of 12,800 mPa s.

Waterborne UV coating for industrial applications

International Nuclear Information System (INIS)

Bhattacharya, I.N.

2007-01-01

(Full Text): Solvent borne industrial coatings are being replaced by environment friendly coatings like Ultra Violet (UV) or Electron Beam (Eb) cured coatings, Powder coatings and Waterborne coatings. Waterborne systems enjoy the biggest share from this shift. UV and EB coatings provide the advantages of instant cure at room temperature, high scratch and abrasion resistance combined with excellent chemical resistance. Polyurethane (PU) chemistry is the dominant chemistry in Industrial coatings as they provide a very high level of performance. Most PU coatings are solvent based 2-component systems comprising of a resin and a cross linker. Polyurethane dispersions (PUD) in water in single pack are available but mainly addresses the Do It Yourself (DIY) market because of their slow drying speeds. Performance of PUD in most cases is inferior to solvent borne 2-component PU systems.Therefore the combination of PU dispersion and UV/EB curable technology has led to new innovative waterborne polymers called UV curable polyurethane dispersions (UVPUD). UVPUD are zero VOC systems as they are coalescent free. They are higher in molecular weight than standard UV curable products resulting in lower shrinkage coatings and provide good adhesion to substrates. Their low-viscosity makes them suitable for application by spray, curtain coater and even roller coater, without having to use monomers. UVPUD display superior chemical and mechanical properties necessary to protect high quality surface from the challenging usage conditions. UVPUD resins are therefore tailor-made to address performance needs like excellence in outdoor durability, scratch resistance, stain resistance, adhesion etc. UVPUD technology is now growing rapidly in industrial coatings for applications such as resilient flooring, wooden parquet flooring, automotive interior plastics, mobile phones etc. (Author)

Flavonoids are systemically induced by UV-B in Zea mays

International Nuclear Information System (INIS)

Tossi, V.E.; Lamattina, L.; Cassia, R.

2009-01-01

Flavonoid concentration is increased by UV-B irradiation, but it is unknown if this is a local or systemic response. Nitric oxide (NO) is a diffusible molecule involved in the UV-B response. NO regulates the expression of chalcone synthase (CHS), a key enzyme in the synthesis of flavonoids. The aim of this work was to determine if maize flavonoids are local or systemically induced by UV-B, and what is the participation of NO in this response. We have used maize seedlings where the second leaf was sprayed with H 2 O or cPTIO (a NO scavenger), and then completely covered (C), partially covered (P) or uncovered (U) before to be UV-B irradiated. The results show a 60% increase in the NO concentration of U, 42% in P and 35% in C respectively. Flavonoid concentration increased 90% in C, 70% in P and 40% in U. Flavonoid concentration was reduced when leaves were pretreated with cPTIO before the UV-B irradiation. RT-PCR shows that CHS was up-regulated by UV-B in U, P and C, but downregulated with cPTIO. We have analyzed the subcellular localization of flavonoid and NO in UV-B irradiated plants. Flavonoid localization was coincident with the NO presence in the irradiated surface of the leaves and flavonoids were detected in vesicles. These results indicate that flavonoids are systemically induced by UV-B in a NO-related mechanism. (authors)

Effectiveness of UV-C light irradiation on disinfection of an eSOS(®) smart toilet evaluated in a temporary settlement in the Philippines.

Science.gov (United States)

Zakaria, Fiona; Harelimana, Bertin; Ćurko, Josip; van de Vossenberg, Jack; Garcia, Hector A; Hooijmans, Christine Maria; Brdjanovic, Damir

2016-01-01

Ultraviolet germicidal (short wavelength UV-C) light was studied as surface disinfectant in an Emergency Sanitation Operation System(®) smart toilet to aid to the work of manual cleaning. The UV-C light was installed and regulated as a self-cleaning feature of the toilet, which automatically irradiate after each toilet use. Two experimental phases were conducted i.e. preparatory phase consists of tests under laboratory conditions and field testing phase. The laboratory UV test indicated that irradiation for 10 min with medium-low intensity of 0.15-0.4 W/m(2) could achieve 6.5 log removal of Escherichia coli. Field testing of the toilet under real usage found that UV-C irradiation was capable to inactivate total coliform at toilet surfaces within 167-cm distance from the UV-C lamp (UV-C dose between 1.88 and 2.74 mW). UV-C irradiation is most effective with the support of effective manual cleaning. Application of UV-C for surface disinfection in emergency toilets could potentially reduce public health risks.

Reversible manipulation of the adhesive forces of TiO{sub 2}/polybenzoxazine nanoassembled coatings through UV irradiation and thermal treatment

Energy Technology Data Exchange (ETDEWEB)

Wang, Sheng-Feng; Kao, Tzu-Hao [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 106, Taiwan, ROC (China); Cheng, Chih-Chia [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan, ROC (China); Chang, Chi-Jung [Department of Chemical Engineering, Feng Chia University, 100, Wenhwa Road, Seatwen, Taichung 40724, Taiwan, ROC (China); Chen, Jem-Kun, E-mail: jkchen@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Section 4, Keelung Road, Taipei 106, Taiwan, ROC (China)

2015-12-01

Graphical abstract: We developed a simple approach, mixing TiO{sub 2} nanoparticles and 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (BA), to obtain a UV-responsive surfaces after thermal treatment. Because the wettability between TiO{sub 2} nanoparticles and BA, a nanoassembled structure was generated on the surface during the coating process. Results indicate that the mixing 30 wt% TiO{sub 2} nanoparticles into PBA matrix generated the superhydrophobic surface (static water contact angle > 150°) with ca. 1° of sliding angle. The superhydrophobic TiO{sub 2}/PBA nanoassembled surface can be converted by photocatalytic oxidation into a highly hydrophilic one (static water contact angle ∼ 0°) within five minimums. Interestingly, the hydrophilic surface can be converted back into a superhydrophobic surface by heat treatment. A water droplet can be transported among the surfaces that UV-irradiated for various times. Velocity of the droplet on the 15°-titled surface could be also manipulated with UV irradiation for various times. The correlations between PBA and TiO{sub 2} nanoparticles would provide insight into the designing and developing of light-responsive surfaces. - Highlights: • Nanoassembly of PBA and TiO{sub 2} NPs are generated with superhydrophobicity. • The superhydrophobicity can be converted to hydrophilic surface within 5 min. • The hydrophilic surface can be converted back into a superhydrophobic surface. • Adhesive force of the nanoassemblies can be manipulated by UV illumination time. - Abstract: In this study we mixed TiO{sub 2} nanoparticles (NPs) with 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (BA), as a precursor to a polybenzoxazine (PBA), to generate nanocomposite surfaces possessing low surface free energies. Because of extreme phase separation between the TiO{sub 2} NPs and BA, their mixtures featured nanoassembled structures on their surfaces. After thermal curing, we obtained PBA/TiO{sub 2} nanoassembled (PTN) surfaces possessing

Metallopolymer capacitor in "one pot" by self-directed UV-assisted process.

Science.gov (United States)

Ijeri, Vijaykumar S; Nair, Jijeesh R; Gerbaldi, Claudio; Bongiovanni, Roberta M; Penazzi, Nerino

2010-11-01

Silver metalized methacrylate films are prepared by single-step UV curing process with good conductivity on both sides. The major component of the composite is Bisphenol A ethoxylate dimethacrylate, which can be photopolymerized by a photoreactive initiator under UV light. Under the same conditions of UV irradiation, silver ions are deposited as metal nanoparticles while the pyrrole is oxidized to polypyrrole. The migration of silver ions and pyrrole toward both surfaces during polymerization leads to the formation of a metallo-polymer capacitor. The composite films are characterized by SEM-EDX and electrical measurements for possible applications as capacitors in flexible and/or nonplanar electronics.

UV-induced reaction kinetics in dilinoleoylphosphatidylcholine monolayers with incorporated photosensitizers

Directory of Open Access Journals (Sweden)

DEJAN MARKOVIC

2006-04-01

Full Text Available Mixed insoluble monolayers (Langmuir films of 1,2-di-O-linoleoyl-3-sn-phosphatidylcholine (1,2-DLPC and incorporated benzophenone-type photosensitizers at an air-water interface were exposed to prolonged UV-irradiation. The irradiation was initiated at a particular fixed molecular packing value. Changes of the surface pressure during the UV-induced photolysis of the sensitizers were plotted against the irradiation time and the results were interpreted in terms of themolecular lipid / sensitizer ratios inside the monolayers.

UV ATTENUATION NEAR CORAL REEFS IN THE FLORIDA KEYS: LIGHT ABSORPTION BY CDOM AND PARTICLES

Science.gov (United States)

We have investigated the roles of chromophoric dissolved organic matter (CDOM) and suspended particles in the attenuation of UV radiation in the middle and lower regions of the Florida Keys. Extended exposure to UV radiation, along with elevated sea surface temperatures, impairs...

Textile UV detector with 2,3,5-triphenyltetrazolium chloride as an active compound

International Nuclear Information System (INIS)

Kozicki, Marek; Sasiadek, Elzbieta

2011-01-01

In this paper, results on the construction of a new flat textile-based UV light dosimeter are reported. As a textile support polyamide woven fabric was chosen, which was surface-modified with 2,3,5-triphenyltetrazolium chloride (TTC). At first, spectrophotometric and dynamic laser light scattering results on the steady-state UV irradiation of aqueous TTC solutions in the presence of oxygen are discussed. If irradiated, TTC converts to the corresponding formazan molecules of red colour. The size and size distribution of the particles is related to the absorbed radiation and pH of the solution. When TTC molecules reside on polyamide textile, UV irradiation causes a colour change from white to deep red. The tinge intensity depends on the absorbed energy per unit surface area. On this basis, the calibration parameters of the detectors, such as dose sensitivity, dose range, quasi-linear dose range, were calculated. Furthermore, the improvement of the dosimeters' resistance to atmospheric conditions was achieved and assessed through washing fastness tests. Finally, the detectors were proved to be adequate for measurements of the 2D distribution of absorbed UV energy. A simple method of UV dose distribution measurements was proposed. The textile-based systems show promise as dosimeters.

COMPARATIVE ANALYSIS OF UV-C AND UV-B RADIATION INFLUENCE ON PLANT OBJECTS

Directory of Open Access Journals (Sweden)

О. Міхєєв

2011-04-01

Full Text Available General aim of work – comparative research of temporal regularities of growth processes of pea,that was grown under normal conditions and with application of UV-C and UV-B irradiation ofstem part, and also detection of irradiation dose relations to parameter of root and stem part sproutsgrowth rate of Aronis pea. Research subject of UV-C and UV-B irradiation influence on dynamicsof plant growth parameters in each set of experiments was alteration of growth rate, pecularities ofgrowth dynamics in different conditions of experiment, detection of UV-C and UV-B irradiationdoses range, that stimulate or inhibit growth parameters of pea sprouts. The investigation resulted indetermination 1,3 times higher efficiency of UV-V irradiation comparing to UV-B irradiation.Reaction of root didn’t depend on the type of UV-radiation

DNA damage caused by UV- and near UV-irradiation

International Nuclear Information System (INIS)

Ohnishi, Takeo

1986-01-01

Much work with mutants deficient in DNA repair has been performed concerning UV-induced DNA damage under the condition where there is no artificial stimulation. In an attempt to infer the effects of solar wavelengths, the outcome of the work is discussed in terms of cellular radiation sensitivity, unscheduled DNA synthesis, and mutation induction, leading to the conclusion that some DNA damage occurs even by irradiation of the shorter wavelength light (270 - 315 nm) and is repaired by excision repair. It has been thought to date that pyrimidine dimer (PD) plays the most important role in UV-induced DNA damage, followed by (6 - 4) photoproducts. As for DNA damage induced by near UV irradiation, the yield of DNA single-strand breaks and of DNA-protein crosslinking, other than PD, is considered. The DNA-protein crosslinking has proved to be induced by irradiation at any wavelength of UV ranging from 260 to 425 nm. Near UV irradiation causes the inhibition of cell proliferation to take place. (Namekawa, K.)

Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln3+-TiO2 surface under UV/solar light

International Nuclear Information System (INIS)

Devi, L. Gomathi; Kumar, S. Girish

2012-01-01

Graphical abstract: The surface reactive acidic sites enhances on doping with rare earth ions which facilitates efficient adsorption of the dye molecules on the catalyst surface. In addition, the nature of the dopant, its concentration and electronic configuration additionally contributes to the overall efficiency. Highlights: ► The degradation of structurally different anionic dyes under different pH conditions is reported. ► Pre adsorption of pollutant on catalyst surface is vital for efficient photocatalysis. ► Adsorption of dye on the catalyst surface depends on the substituent's attached to it. ► The dopant with half filled electronic configuration served as shallow traps for charge carriers. - Abstract: The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln 3+ (Ln 3+ = La 3+ , Ce 3+ and Gd 3+ ) doped TiO 2 at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd 3+ (0.15 mol%)-TiO 2 exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd 3+ ions. It is proposed that Ln 3+ serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

Decontamination of poultry feed from ochratoxin A by UV and sunlight radiations.

Science.gov (United States)

Ameer Sumbal, Gul; Hussain Shar, Zahid; Hussain Sherazi, Syed Tufail; Sirajuddin; Nizamani, Shafi Muhammad; Mahesar, Safaraz Ahmed

2016-06-01

Mycotoxin-contaminated feed is very dangerous for the growth and even life of poultry. The objective of the current study was to investigate the efficacy of ultra-violet irradiation for decontamination of ochratoxin A (OTA) in spiked and naturally contaminated poultry feed samples. Spiked and naturally contaminated feed samples were irradiated with ultra-violet light (UV) at distance of 25 cm over the feed samples. In vitro, the effect of UV intensity (0.1 mW cm(-2) at 254 nm UV-C) on different types of poultry feeds contaminated with OTA was evaluated. The same samples were also irradiated with sunlight and analysed for OTA by an indirect enzyme linked immunosorbent assay method. Poultry feed samples containing 500 µg kg(-1) were 100% decontaminated in 180 min with UV radiation while OTA was decreased to 70-95 µg kg(-1) using the same poultry feed samples after 8 h sunlight irradiation. Therefore, UV light was found to be more effective. Only 1 h of UV irradiation was found to be sufficient to bring the OTA level to the maximum regulatory limit suggested for poultry feeds (100 µg kg(-1) ), while 8 h were needed to obtain this level using sunlight radiations. The proposed approach is a viable option to reduce the level of OTA in contaminated poultry feeds. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

UV-B photoreceptor-mediated protection of the photosynthetic machinery in Chlamydomonas reinhardtii

Science.gov (United States)

Allorent, Guillaume; Lefebvre-Legendre, Linnka; Chappuis, Richard; Kuntz, Marcel; Truong, Thuy B.; Niyogi, Krishna K.; Goldschmidt-Clermont, Michel

2016-01-01

Life on earth is dependent on the photosynthetic conversion of light energy into chemical energy. However, absorption of excess sunlight can damage the photosynthetic machinery and limit photosynthetic activity, thereby affecting growth and productivity. Photosynthetic light harvesting can be down-regulated by nonphotochemical quenching (NPQ). A major component of NPQ is qE (energy-dependent nonphotochemical quenching), which allows dissipation of light energy as heat. Photodamage peaks in the UV-B part of the spectrum, but whether and how UV-B induces qE are unknown. Plants are responsive to UV-B via the UVR8 photoreceptor. Here, we report in the green alga Chlamydomonas reinhardtii that UVR8 induces accumulation of specific members of the light-harvesting complex (LHC) superfamily that contribute to qE, in particular LHC Stress-Related 1 (LHCSR1) and Photosystem II Subunit S (PSBS). The capacity for qE is strongly induced by UV-B, although the patterns of qE-related proteins accumulating in response to UV-B or to high light are clearly different. The competence for qE induced by acclimation to UV-B markedly contributes to photoprotection upon subsequent exposure to high light. Our study reveals an anterograde link between photoreceptor-mediated signaling in the nucleocytosolic compartment and the photoprotective regulation of photosynthetic activity in the chloroplast. PMID:27930292

UV-B photoreceptor-mediated protection of the photosynthetic machinery in Chlamydomonas reinhardtii.

Science.gov (United States)

Allorent, Guillaume; Lefebvre-Legendre, Linnka; Chappuis, Richard; Kuntz, Marcel; Truong, Thuy B; Niyogi, Krishna K; Ulm, Roman; Goldschmidt-Clermont, Michel

2016-12-20

Life on earth is dependent on the photosynthetic conversion of light energy into chemical energy. However, absorption of excess sunlight can damage the photosynthetic machinery and limit photosynthetic activity, thereby affecting growth and productivity. Photosynthetic light harvesting can be down-regulated by nonphotochemical quenching (NPQ). A major component of NPQ is qE (energy-dependent nonphotochemical quenching), which allows dissipation of light energy as heat. Photodamage peaks in the UV-B part of the spectrum, but whether and how UV-B induces qE are unknown. Plants are responsive to UV-B via the UVR8 photoreceptor. Here, we report in the green alga Chlamydomonas reinhardtii that UVR8 induces accumulation of specific members of the light-harvesting complex (LHC) superfamily that contribute to qE, in particular LHC Stress-Related 1 (LHCSR1) and Photosystem II Subunit S (PSBS). The capacity for qE is strongly induced by UV-B, although the patterns of qE-related proteins accumulating in response to UV-B or to high light are clearly different. The competence for qE induced by acclimation to UV-B markedly contributes to photoprotection upon subsequent exposure to high light. Our study reveals an anterograde link between photoreceptor-mediated signaling in the nucleocytosolic compartment and the photoprotective regulation of photosynthetic activity in the chloroplast.

Spectroscopic investigation of oxidized solder surfaces

International Nuclear Information System (INIS)

Song, Jenn-Ming; Chang-Chien, Yu-Chien; Huang, Bo-Chang; Chen, Wei-Ting; Shie, Chi-Rung; Hsu, Chuang-Yao

2011-01-01

Highlights: → UV-visible spectroscopy is successfully used to evaluate the degree of discoloring of solders. → The surface oxides of solders can also be identified by UV-visible absorption spectra. → The discoloration of solder surface can be correlated with optical characterization of oxides. → A strategy against discoloring by alloying was also suggested. - Abstract: For further understanding of the discoloration of solder surfaces due to oxidation during the assembly and operation of electronic devices, UV-vis and X-ray photoelectron spectroscopic analyses were applied to evaluate the degree of discoloring and identify the surface oxides. The decrease in reflectance of the oxidized solder surface is related to SnO whose absorption band is located within the visible region. A trace of P can effectively depress the discoloration of solders under both solid and semi-solid states through the suppression of SnO.

Surface ozone concentrations in Europe: Links with the regional-scale atmospheric circulation

Science.gov (United States)

Davies, T. D.; Kelly, P. M.; Low, P. S.; Pierce, C. E.

1992-06-01

Daily surface ozone observations from 1978 (1976 for some analyses) to 1988 for Bottesford (United Kingdom), Cabauw, Kloosterburen (The Netherlands), Hohenpeissenberg, Neuglobsow, Hamburg, and Arkona (Germany) are used to analyze links between surface ozone variations and the atmospheric circulation. A daily Europe-wide synoptic classification highlights marked differences between surface ozone/meteorology relationships in summer and winter. These relationships are characterized by correlations between daily surface ozone concentrations at each station and a local subregional surface pressure gradient (a wind speed index). Although there are geographical variations, which are explicable in terms of regional climatology, there are distinct annual cycles. In summer, the surface ozone/wind speed relationship exhibits the expected negative sign; however, in winter, the relationship is, in the main, strongly positive, especially at those stations which are more influenced by the vigorous westerlies. Spring and autumn exhibit negative, positive, or transitional (between summer and winter) behavior, depending on geographical position. It is suggested that these relationships reflect the importance of vertical exchange from the free troposphere to the surface in the nonsummer months. Composite surface pressure patterns and surface pressure anomaly (from the long-term mean) patterns associated with high surface ozone concentrations on daily and seasonal time scales are consistent with the surface ozone/wind speed relationships. Moreover, they demonstrate that high surface ozone concentrations, in a climatological time frame, can be associated with mean surface pressure patterns which have a synoptic reality and are robust. Such an approach may be useful in interpreting past variations in surface ozone and may help to isolate the effect of human activity. It is also possible that assessments can be made of the effect of projected future changes in the atmospheric circulation

Insights into the early dissolution events of amlodipine using UV imaging and Raman spectroscopy

DEFF Research Database (Denmark)

Boetker, Johan P; Savolainen, Marja; Koradia, Vishal

2011-01-01

Traditional dissolution testing determines drug release to the bulk, but does not enable an understanding of the events happening close to the surface of a solid or a tablet. UV imaging is a new imaging approach that can be used to study the dissolution behavior of chemical compounds. The UV imag...

Pretreatment with UV light renders the chromatin in human fibroblasts more susceptible to the DNA-damaging agents bleomycin, gamma radiation and 8-methoxypsoralen

International Nuclear Information System (INIS)

Ljungman, Mats

1989-01-01

Confluent human fibroblast cultures were pretreated with either 254 nm UV light (UV) or methyl methanesulphonate (MMS), incubated at 37 0 C and subsequently challenged on ice with bleomycin (BLM), gamma-radiation or 8-methoxy-psoralen (MOP). The resulting number of challenge-induced DNA damages (measured as DNA strand breaks or cross-links) were compared with the numbers induced in similarly challenged but non-pretreated control cells. It was found that the timing of the subsequent challenge of cells pretreated with UV did significantly affect the amount of induced DNA damage. When the challenging agents were administered after a 10-20 min incubation period following UV pretreatment, the amount of induced DNA damage was increased 50% over control cells. In contrast, the timing of the subsequent challenge of cells pretreated with MMS has no influence on the level of challenge-induced damage. It is hypothesized that UV-irradiated chromatin undergoes a time-dependent decondensation that renders it more susceptible to the induction of strand breaks and cross-links by BLM, gamma-radiation and MOP. A possible role for chromatin decondensation in UV-induced excision repair is discussed. (author)

Expression of UV-irradiated adenovirus in normal and UV-sensitive Chinese hamster ovary cells

International Nuclear Information System (INIS)

Rainbow, A.J.

1985-01-01

The chinese hamster ovary (CHO) cell mutants UV-20, UV-24, and UV-41 are abnormally sensitive to UV and harbour various defects lin their ability to repair cellular DNA. This study has examined the expression of UV-irradiated AD2 in these cells. HCR of UV-irradiated Ad2, as measured by viral structural antigen (Vag) formation or progeny production, was found to be similar for the normal and the UV-sensitive CHO strains. UV-irradiation of Ad2 (1200 J/m/sup 2/) resulted in a delay of Vag expression of 18 hours in normal human fibroblasts, which is thought to reflect the time required for removal of UV-induced lesions from the DNA before viral DNA synthesis can proceed. However, a similar UV-irradiation of Ad2 did not result in a delay of Vag expression for infection of CHO cells, suggesting that UV-induced lesions in Ad2 DNA do not inhibit its replication in CHO cells. These results indicate a fundamental difference in the processing of UV-irradiated AD2-DNA in CHO as compared to human cells

Absorption of uv-radiation by Chibro trademark -Uvelin eye drops

International Nuclear Information System (INIS)

Schreder, J.G.; Blumthaler, M.; Daxer, A.; Ettl, A.

1998-01-01

The preparation Chibro trademark -Uvelin is recommended against both solar and artificial uv-radiation. At wavelengths greater than 290 nm and at an effective layer thickness of 10 μm measurements with a high resolution doublemonochromator showed a transmission larger than 90%. The solar spectrum is characterised by almost no irradiance on the earth's surface for wavelengths smaller than 290 nm due to absorption in the atmospheric ozon layer. Therefore, no significant protective effect of the eye-drops against keratitis and cataract under solar exposure can be expected. A significantly better sagging of the radiation of artificial UV-sources with a high amount of UV-C is reached. The recommended application as chemical protective goggles in this spectral range is not permissible. (orig.) [de

Índice UV

Science.gov (United States)

Información general sobre el Índice UV que proporciona un pronóstico del riesgo esperado de sobreexposición a la radiación ultravioleta (UV) del sol. El índice UV va acompañado de recomendaciones para protegerse del sol.

Spectral dependence of some UV-B and UV-C responses of Tetrahymena pyriformis irradiated with dye laser generated UV

International Nuclear Information System (INIS)

Calkins, John; Colley, Ed; Wheeler, John; Kentucky Univ., Lexington

1987-01-01

We have generated UV-B and UV-C radiations using a flashlamp driven tunable dye laser combined with frequency doubling crystals. Using this novel UV source, we have investigated lethality and its modification by growth phase, photoreactivation and caffeine in Tetrahymena pyriformis at 254 nm and from 260-315 nm in 5 nm steps. From the observed responses we have constructed action spectra for lethality, with or without caffeine (a repair inhibitor) and under conditions of photoreactivation. We have also estimated quantum efficiencies for these responses. Our observations suggest that complex changes in response occur at several wavelengths over the UV-C and UV-B regions. (author)

Influence of slight microstructural gradients on the surface properties of Ti6Al4V irradiated by UV

International Nuclear Information System (INIS)

Gallardo-Moreno, A.M.; Multigner, M.; Pacha-Olivenza, M.A.; Lieblich, M.; Jimenez, J.A.; Gonzalez-Carrasco, J.L.; Gonzalez-Martin, M.L.

2009-01-01

Ti6Al4V alloy is one of the most widely used materials for biomedical implants. Among its properties, it is remarkable the photoactivity displayed by its passive layer, which is mainly composed by titanium dioxide. However, variations in the processing conditions may yield to differences in the microstructure which can be reflected on the surface properties of the machined product. From contact angle measurements taken on different zones of samples removed from a commercial bar of Ti6Al4V, it has been shown that the modifications of the surface Gibbs energy suffered by the alloy under UV irradiation have a radial dependence. This behaviour is related to slight microstructural changes of the alloy, particularly with an increase in the volume fraction of the β-phase when moving to the interior of the sample, which alters the composition and/or microstructure of the passive layer along its radius. This study shows that gradients in the microstructure and physical properties are sample size dependent and are likely related to thermal gradients during processing.

Improved functionality of graphene and carbon nanotube hybrid foam architecture by UV-ozone treatment

Science.gov (United States)

Wang, Wei; Ruiz, Isaac; Lee, Ilkeun; Zaera, Francisco; Ozkan, Mihrimah; Ozkan, Cengiz S.

2015-04-01

Optimization of the electrode/electrolyte double-layer interface is a key factor for improving electrode performance of aqueous electrolyte based supercapacitors (SCs). Here, we report the improved functionality of carbon materials via a non-invasive, high-throughput, and inexpensive UV generated ozone (UV-ozone) treatment. This process allows precise tuning of the graphene and carbon nanotube hybrid foam (GM) transitionally from ultrahydrophobic to hydrophilic within 60 s. The continuous tuning of surface energy can be controlled by simply varying the UV-ozone exposure time, while the ozone-oxidized carbon nanostructure maintains its integrity. Symmetric SCs based on the UV-ozone treated GM foam demonstrated enhanced rate performance. This technique can be readily applied to other CVD-grown carbonaceous materials by taking advantage of its ease of processing, low cost, scalability, and controllability.Optimization of the electrode/electrolyte double-layer interface is a key factor for improving electrode performance of aqueous electrolyte based supercapacitors (SCs). Here, we report the improved functionality of carbon materials via a non-invasive, high-throughput, and inexpensive UV generated ozone (UV-ozone) treatment. This process allows precise tuning of the graphene and carbon nanotube hybrid foam (GM) transitionally from ultrahydrophobic to hydrophilic within 60 s. The continuous tuning of surface energy can be controlled by simply varying the UV-ozone exposure time, while the ozone-oxidized carbon nanostructure maintains its integrity. Symmetric SCs based on the UV-ozone treated GM foam demonstrated enhanced rate performance. This technique can be readily applied to other CVD-grown carbonaceous materials by taking advantage of its ease of processing, low cost, scalability, and controllability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06795a

Transformation of UV-hypersensitive Chinese hamster ovary cell mutants with UV-irradiated plasmids

International Nuclear Information System (INIS)

Nairn, R.S.; Humphrey, R.M.; Adair, G.M.

1988-01-01

Transfection of UV-hypersensitive, DNA repair-deficient Chinese hamster ovary (CHO) cell lines and parental, repair-proficient CHO cells with UV-irradiated pHaprt-1 or pSV2gpt plasmids resulted in different responses by recipient cell lines to UV damage in transfected DNA. Unlike results reported for human cells, UV irradiation of transfecting DNA did not stimulate genetic transformation of CHO recipient cells. In repair-deficient CHO cells, proportionally fewer transformants were produced with increasing UV damage than in repair-proficient cells in transfections with UV-irradiated hamster adenine phosphoribosyltransferase (APRT) gene contained in plasmid pHaprt-1. Transfection of CHO cells with UV-irradiated pSV2gpt resulted in neither decline in transformation frequencies in repair-deficient cell lines relative to repair-proficient cells nor stimulation of genetic transformation by UV damage in the plasmid. Blot hybridization analysis of DNA samples isolated from transformed cells showed no dramatic changes in copy number or arrangement of transfected plasmid DNA with increasing UV dose. The authors conclude responses of recipient cells to UV-damaged transfecting plasmids depend on type of recipient cell and characteristics of the genetic sequence used for transfection. (author)

Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

Science.gov (United States)

Nikzad, Shouleh; Hoenk, Michael; Jewell, April D.; Hennessy, John J.; Carver, Alexander G.; Jones, Todd J.; Goodsall, Timothy M.; Hamden, Erika T.; Suvarna, Puneet; Bulmer, J.; Shahedipour-Sandvik, F.; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L. Douglas

2016-01-01

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

Modified divergence theorem for analysis and optimization of wall reflecting cylindrical UV reactor

Directory of Open Access Journals (Sweden)

Milanović Đurđe R.

2011-01-01

Full Text Available In this paper, Modified Divergence Theorem (MDT, known in earlier literature as Gauss-Ostrogradsky theorem, was formulated and proposed as a general approach to electromagnetic (EM radiation, especially ultraviolet (UV radiation reactor modeling. Formulated mathematical model, based on MDT, for multilamp UV reactor was applied to all sources in a reactor in order to obtain intensity profiles at chosen surfaces inside reactor. Applied modification of MDT means that intensity at a real opaque or transparent surface or through a virtual surface, opened or closed, from different sides of the surface are added and not subtracted as in some other areas of physics. Derived model is applied to an example of the multiple UV sources reactor, where sources are arranged inside a cylindrical reactor at the coaxial virtual cylinder, having the radius smaller than the radius of the reactor. In this work, optimization of a reactor means maximum transfer of EM energy sources into the fluid for given fluid absorbance and fluid flow-dose product. Obtained results, for in advanced known water quality, gives unique solution for an optimized model of a multilamp reactor geometry. As everyone can easily verify, MDT is very good starting point for every reactor modeling and analysis.

Stratospheric ozone changes under solar geoengineering: implications for UV exposure and air quality

Science.gov (United States)

Nowack, Peer Johannes; Abraham, Nathan Luke; Braesicke, Peter; Pyle, John Adrian

2016-03-01

Various forms of geoengineering have been proposed to counter anthropogenic climate change. Methods which aim to modify the Earth's energy balance by reducing insolation are often subsumed under the term solar radiation management (SRM). Here, we present results of a standard SRM modelling experiment in which the incoming solar irradiance is reduced to offset the global mean warming induced by a quadrupling of atmospheric carbon dioxide. For the first time in an atmosphere-ocean coupled climate model, we include atmospheric composition feedbacks for this experiment. While the SRM scheme considered here could offset greenhouse gas induced global mean surface warming, it leads to important changes in atmospheric composition. We find large stratospheric ozone increases that induce significant reductions in surface UV-B irradiance, which would have implications for vitamin D production. In addition, the higher stratospheric ozone levels lead to decreased ozone photolysis in the troposphere. In combination with lower atmospheric specific humidity under SRM, this results in overall surface ozone concentration increases in the idealized G1 experiment. Both UV-B and surface ozone changes are important for human health. We therefore highlight that both stratospheric and tropospheric ozone changes must be considered in the assessment of any SRM scheme, due to their important roles in regulating UV exposure and air quality.

Diversity in UV sensitivity and recovery potential among bacterioneuston and bacterioplankton isolates.

Science.gov (United States)

Santos, A L; Lopes, S; Baptista, I; Henriques, I; Gomes, N C M; Almeida, A; Correia, A; Cunha, A

2011-04-01

To assess the variability in UV-B (280-320 nm) sensitivity of selected bacterial isolates from the surface microlayer and underlying water of the Ria de Aveiro (Portugal) estuary and their ability to recover from previous UV-induced stress. Bacterial suspensions were exposed to UV-B radiation (3·3 W m⁻²). Effects on culturability and activity were assessed from colony counts and (3) H-leucine incorporation rates, respectively. Among the tested isolates, wide variability in UV-B-induced inhibition of culturability (37·4-99·3%) and activity (36·0-98·0%) was observed. Incubation of UV-B-irradiated suspensions under reactivating regimes (UV-A, 3·65 W m⁻²; photosynthetic active radiation, 40 W m⁻²; dark) also revealed diversity in the extent of recovery from UV-B stress. Trends of enhanced resistance of culturability (up to 15·0%) and enhanced recovery in activity (up to 52·0%) were observed in bacterioneuston isolates. Bacterioneuston isolates were less sensitive and recovered more rapidly from UV-B stress than bacterioplankton isolates, showing enhanced reduction in their metabolism during the irradiation period and decreased culturability during the recovery process compared to bacterioplankton. UV exposure can affect the diversity and activity of microbial communities by selecting UV-resistant strains and alter their metabolic activity towards protective strategies. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

Effects of UV assistance on the properties of al-doped ZnO thin films deposited by sol-gel method

Science.gov (United States)

Tseng, Yung-Kuan; Pai, Feng-Ming; Chen, Yan-Cheng; Wu, Chao-Hsien

2013-11-01

We report here the preparation of aluminum doped zinc oxide transparent conductive thin films by a UV-assisted sol-gel method. It was found that UV irradiation creates ozone, which promotes the conductivity and transparency of the films. Boro-silicate glasses are used as substrates; an PGME is used as a solvent; after spin-coating, the films are dried and radiated with UV and then heated to 400°C for decarburization and 500°C for annealing under air. The surface morphologies of the prepared films are observed by FE-SEM and AFM. It was found that the films irradiated with UV-C are smoother and denser. An XRD analysis shows that the films have a typical wurtzite crystalline structure with a c-axis orientation normal to the surface. The electric resistance values measured with a four-point probe show that the films irradiated with UV have better conductivity (at approximately 3.4 × 10-3Ω-cm) than the films that did not undergo UV irradiation. An analysis by visible light spectrometry indicates that the AZO films irradiated with UV are more transparent than the films without UV-irradiation.

Polymer-ZnO nanocomposites foils and thin films for UV protection

International Nuclear Information System (INIS)

Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya; Yunus, Wan Mahmood Mat

2014-01-01

The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images

Polymer-ZnO nanocomposites foils and thin films for UV protection

Energy Technology Data Exchange (ETDEWEB)

Shanshool, Haider Mohammed; Yahaya, Muhammad; Abdullah, Ibtisam Yahya [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Yunus, Wan Mahmood Mat [Department of Physics, Faculty of Science, University Putra Malaysia, 43400 UPM, Serdang (Malaysia)

2014-09-03

The damage of UV radiation on human eye and skin is extensively studied. In the present work, the nanocomposites foils and thin films have been prepared by using casting method and spin coating, respectively. Nanocomposites were prepared by mixing ZnO nanoparticles with Polymethyl methacrylate (PMMA) and Polyvinylidene fluoride (PVDF) as polymer matrix. Different contents of ZnO nanoparticles were used as filler in the nanocomposites. UV-Vis spectra showed very low transmittance in UV region that decreases with increase content of ZnO. PVDF/ZnO samples showed the lowest transmittance. The rough surface of PVDF was observed from SEM image. While a homogeneous dispersion of ZnO nanoparticles in PMMA were indicated by FESEM images.

Thermal Degradation and Damping Characteristic of UV Irradiated Biopolymer

Directory of Open Access Journals (Sweden)

Anika Zafiah M. Rus

2015-01-01

Full Text Available Biopolymer made from renewable material is one of the most important groups of polymer because of its versatility in application. In this study, biopolymers based on waste vegetable oil were synthesized and cross-link with commercial polymethane polyphenyl isocyanate (known as BF. The BF was compressed by using hot compression moulding technique at 90°C based on the evaporation of volatile matter, known as compress biopolymer (CB. Treatment with titanium dioxide (TiO2 was found to affect the physical property of compressed biopolymer composite (CBC. The characterization of thermal degradation, activation energy, morphology structure, density, vibration, and damping of CB were determined after UV irradiation exposure. This is to evaluate the photo- and thermal stability of the treated CB or CBC. The vibration and damping characteristic of CBC samples is significantly increased with the increasing of UV irradiation time, lowest thickness, and percentages of TiO2 loading at the frequency range of 15–25 Hz due to the potential of the sample to dissipate energy during the oscillation harmonic system. The damping property of CBC was improved markedly upon prolonged exposure to UV irradiation.

Cyclobutyl pyrimidine dimer accumulation in relation to UV-B sensitivity in mung bean cultivars

International Nuclear Information System (INIS)

He Junmin; Wang Ruibin; Meng Zhaoni

2006-01-01

The purpose of the experiment is to reveal the relationship between cyclobutyl pyrimidine dimers (CPDs) accumulation and UV-B sensitivity in mung bean cultivars. Two mung bean cultivars (Phaseolus raditus L. cv. Qindou -2 0 and Zhonglü -1 ) were grown in greenhouse with treatment or without treatment of UV-B radiation (0.4 W * m -2 ) for four days. The UV-B-induced CPDs in mung bean DNA were quantified by enzyme-linked immunosorbent assay (ELISA) with specific monoclonal antibody and the relationship between CPDs accumulation and the UV-B sensitivity of mung bean seedlings were discussed. The UV-B-induced inhibition of the biomass and net photosynthetic rate of the primary leaves of cultivar Zhonglü -1 were respectively lower than that of cultivar Qindou -2 0, so that the cultivar Zhonglü -1 was more tolerant to UV-B than the cultivar Qindou -2 0. Meanwhile, the cultivar Zhonglü -1 had lower CPD accumulation and susceptibility to CPD induction, higher photorepair capacity and same dark repair capacity as compared with the cultivar Qindou -2 0. Different UV-B sensitivities between two mung bean cultivars may be mainly caused by the differences in CPD accumulation, which are caused by the different susceptibility to CPD induction and the different photorepair capacities. In addition, the different susceptibility to CPD induction between two mung bean cultivars is related to the different levels of UV-absorbing compounds

Polymer surface modification using UV treatment for attachment of natamycin and the potential applications for conventional food cling wrap (LDPE)

Energy Technology Data Exchange (ETDEWEB)

Shin, Joongmin, E-mail: shinj@uwstout.edu [Engineering and Technology, University of Wisconsin-Stout, Menomonie, WI, 54751 (United States); Liu, Xiaojing [Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan (China); Chikthimmah, Naveen [Food Science and Technology, University of Wisconsin-Stout, Menomonie, WI, 54751 (United States); Lee, Youn Suk [Department of Packaging, Yonsei University, Gangwon 220-710 (Korea, Republic of)

2016-11-15

Highlights: • The study suggests an optimized method for UV-induced antimicrobial agents grafting on LDPE. • The study evaluated the effective of various solvents for acrylic acid and natamycin grafting on LDPE. • The study investigated chemical and mechanical property changes by various times of UV light treatments. • Natamycin grafted film demonstrated antifungal function against mold and yeast. - Abstract: The purpose of this study was to develop an active non-migratory antifungal Low Density Polyethylene (LDPE) polymer for use in food packaged applications. The functional acrylic acid monomer was grafted on the LDPE film surface by photo-initiated graft polymerization using Ultra Violet light irradiation (from 0 to 5 min). Natamycin, an antifungal agent, was applied to the treated film to bind with the pendent functional groups and were evaluated its performance against mold and yeast. The grafted amounts were determined by gravimetric measurement and dye absorbance. Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy, scanning electron microscopy, mechanical strength test was used to characterize film properties. The antifungal efficacy of the film was evaluated with Saccharomyces cerevisiae and Penicillium chrysogenum on growth media and fresh cut cantaloupe. The amounts of the grafted group were increased with the longer ultraviolet exposure time. The amount of the grafted natamycin on the treated film was up to 49.87 μg/cm{sup 2}, and the film inhibited mycelium formation of P. chrysogenum spores by over 60%. Due to the thickness of the film (less than 12.25 μm), long time UV exposure decrease the film’s mechanical strength. The application of such non-migratory active packaging film represents a promising approach to maintaining food quality with reduced additive.

Polymer surface modification using UV treatment for attachment of natamycin and the potential applications for conventional food cling wrap (LDPE)

International Nuclear Information System (INIS)

Shin, Joongmin; Liu, Xiaojing; Chikthimmah, Naveen; Lee, Youn Suk

2016-01-01

Highlights: • The study suggests an optimized method for UV-induced antimicrobial agents grafting on LDPE. • The study evaluated the effective of various solvents for acrylic acid and natamycin grafting on LDPE. • The study investigated chemical and mechanical property changes by various times of UV light treatments. • Natamycin grafted film demonstrated antifungal function against mold and yeast. - Abstract: The purpose of this study was to develop an active non-migratory antifungal Low Density Polyethylene (LDPE) polymer for use in food packaged applications. The functional acrylic acid monomer was grafted on the LDPE film surface by photo-initiated graft polymerization using Ultra Violet light irradiation (from 0 to 5 min). Natamycin, an antifungal agent, was applied to the treated film to bind with the pendent functional groups and were evaluated its performance against mold and yeast. The grafted amounts were determined by gravimetric measurement and dye absorbance. Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy, scanning electron microscopy, mechanical strength test was used to characterize film properties. The antifungal efficacy of the film was evaluated with Saccharomyces cerevisiae and Penicillium chrysogenum on growth media and fresh cut cantaloupe. The amounts of the grafted group were increased with the longer ultraviolet exposure time. The amount of the grafted natamycin on the treated film was up to 49.87 μg/cm"2, and the film inhibited mycelium formation of P. chrysogenum spores by over 60%. Due to the thickness of the film (less than 12.25 μm), long time UV exposure decrease the film’s mechanical strength. The application of such non-migratory active packaging film represents a promising approach to maintaining food quality with reduced additive.

Comets in UV

Science.gov (United States)

Shustov, B.; Sachkov, M.; Gómez de Castro, A. I.; Vallejo, J. C.; Kanev, E.; Dorofeeva, V.

2018-04-01

Comets are important "eyewitnesses" of Solar System formation and evolution. Important tests to determine the chemical composition and to study the physical processes in cometary nuclei and coma need data in the UV range of the electromagnetic spectrum. Comprehensive and complete studies require additional ground-based observations and in situ experiments. We briefly review observations of comets in the ultraviolet (UV) and discuss the prospects of UV observations of comets and exocomets with space-borne instruments. A special reference is made to the World Space Observatory-Ultraviolet (WSO-UV) project.

Is the surface oxygen exchange rate linked to bulk ion diffusivity in mixed conducting Ruddlesden-Popper phases?

Science.gov (United States)

Tomkiewicz, Alex C; Tamimi, Mazin A; Huq, Ashfia; McIntosh, Steven

2015-01-01

The possible link between oxygen surface exchange rate and bulk oxygen anion diffusivity in mixed ionic and electronic conducting oxides is a topic of great interest and debate. While a large body of experimental evidence and theoretical analyses support a link, observed differences between bulk and surface composition of these materials are hard to reconcile with this observation. This is further compounded by potential problems with simultaneous measurement of both parameters. Here we utilize separate techniques, in situ neutron diffraction and pulsed isotopic surface exchange, to examine bulk ion mobility and surface oxygen exchange rates of three Ruddlesden-Popper phases, general form A(n-1)A(2)'B(n)O(3n+1), A(n-1)A(2)'B(n)X(3n+1); LaSrCo(0.5)Fe(0.5)O(4-δ) (n = 1), La(0.3)Sr(2.7)CoFeO(7-δ) (n = 2) and LaSr3Co(1.5)Fe(1.5)O(10-δ) (n = 3). These measurements are complemented by surface composition determination via high sensitivity-low energy ion scattering. We observe a correlation between bulk ion mobility and surface exchange rate between materials. The surface exchange rates vary by more than one order of magnitude with high anion mobility in the bulk of an oxygen vacancy-rich n = 2 Ruddlesden-Popper material correlating with rapid oxygen exchange. This is in contrast with the similar surface exchange rates which we may expect due to similar surface compositions across all three samples. We conclude that experimental limitations lead to inherent convolution of surface and bulk rates, and that surface exchange steps are not likely to be rate limiting in oxygen incorporation.

Interaction of the wood surface with metal ions. Part 3: The effects of light on chromium impregnated wood surface

International Nuclear Information System (INIS)

Stipta, J.; Németh, K.; Molnárné Hamvas, L.

2004-01-01

UV-light changes of untreated and chromium impregnated wood surface were investigated by absorption spectrophotometric methods. The properties of indifferent silicagel and celulose layers were to the behaviour of poplar and black locust surface. Chromic-ion-impregnation had no significant effect on the absorption spectra of these layers. On the other hand, hexavalent chromium was reduced and UV-light caused irreversible wood degradation. Surface treatment caused considerable modification in black locust

Climatology of surface ultraviolet-radiation in Valparaiso, Chile

International Nuclear Information System (INIS)

Cordero, Raul R.; Roth, Pedro; Georgiev, Aleksandar; Silva, Luis da

2005-01-01

Despite the lack of long-term records, it is possible to describe many of the short term characteristics, dependencies and climatology of surface UV irradiance. This paper describes the climatology of on ground UV irradiance at Valparaiso (33.05 deg. S, 71.63 deg. W, sea level), Chile. The dependence of UV-B irradiance on ozone and on other climate variables is discussed with reference to our observations conducted during the last four years. Special attention was paid to detect 'ozone events' by surface UV irradiance measurements. By analyzing time series of the UV-B/UV-A ratio, we suppressed the cloud variability effect and detected events that implied ozone column changes of about 15%. According to our measurements, during the last four years, the ozone column over Valparaiso was not affected negatively by the Antarctic ozone hole phenomenon

Protocol for Determining Ultraviolet Light Emitting Diode (UV-LED) Fluence for Microbial Inactivation Studies.

Science.gov (United States)

Kheyrandish, Ataollah; Mohseni, Madjid; Taghipour, Fariborz

2018-06-15

Determining fluence is essential to derive the inactivation kinetics of microorganisms and to design ultraviolet (UV) reactors for water disinfection. UV light emitting diodes (UV-LEDs) are emerging UV sources with various advantages compared to conventional UV lamps. Unlike conventional mercury lamps, no standard method is available to determine the average fluence of the UV-LEDs, and conventional methods used to determine the fluence for UV mercury lamps are not applicable to UV-LEDs due to the relatively low power output, polychromatic wavelength, and specific radiation profile of UV-LEDs. In this study, a method was developed to determine the average fluence inside a water suspension in a UV-LED experimental setup. In this method, the average fluence was estimated by measuring the irradiance at a few points for a collimated and uniform radiation on a Petri dish surface. New correction parameters were defined and proposed, and several of the existing parameters for determining the fluence of the UV mercury lamp apparatus were revised to measure and quantify the collimation and uniformity of the radiation. To study the effect of polychromatic output and radiation profile of the UV-LEDs, two UV-LEDs with peak wavelengths of 262 and 275 nm and different radiation profiles were selected as the representatives of typical UV-LEDs applied to microbial inactivation. The proper setup configuration for microorganism inactivation studies was also determined based on the defined correction factors.

UV-activated 7-dehydrocholesterol-coated titanium implants promote differentiation of human umbilical cord mesenchymal stem cells into osteoblasts.