Routine measurement of erythemally effective UV irradiance on inclined surfaces

Measurements of erythemally weighted UV radiation are usually related to a horizontal surface. The radiation is weighted with the sensitivity of the human skin, but the surface of the human body has only few horizontal surfaces. Therefore the UV radiation on inclined surfaces has to be quantified to investigate UV effects on humans. To fulfill this task three fully automatic measuring systems were built to measure the erythemally weighted UV radiation in 27 directions within 2 min. This system measures routinely during the whole day and has now been in operation for nearly three years (in total 2000 measurement days) under any kind of meteorological conditions. The measurements provide the informations needed for further investigations concerning the UV effects on humans. The calibration of the erythemally weighting radiometers was performed in a way to provide reliable UV index measurements for all directions. The results of four exemplary measurement days in summer and winter for clear sky and overcast conditions are presented.     

Multi-waveband solar irradiance on tree-shaded vertical and horizontal surfaces: cloud-free and partly cloudy skies

Irradiance measurements of short wave (SW), photosynthetically active (PAR), ultraviolet-A (UVA) and ultraviolet-B (UVB) solar radiations were made on horizontal and vertical surfaces in the shade of trees under cloud-free and partly cloudy skies. All measurements were referenced to the irradiance of a horizontal surface above the canopy. For horizontal shaded surfaces under cloud-free skies, the values of the ratio (Rh) of below- to above-canopy horizontal irradiance were similar for the UVA and UVB wavebands and for the SW and PAR wavebands. However, Rh for the UV wavebands differed from that for the PAR and SW wavebands. Overall, values of Rh in the shade typically varied as PAR < SW < UVA < UVB. The irradiance ratios for vertical surface in the shade typically varied as UVB > UVA = SW > PAR. In absolute terms, UVB irradiance (Ih) on tree-shaded horizontal surfaces increased relative to a cloud-free sky when a translucent cirroform cloud was in front of the sun, but decreased when the cloud was in a region of sky away from the sun. Translucent cirroform cloud cover also tended to decrease the UVB irradiance (Iv) for a shaded vertical surface (either facing the sun or south) relative to that under cloud-free skies, regardless of where the clouds were in the sky. In all other wavebands the shaded Ih and Iv increased under translucent cirroform cloud cover relative to cloud-free skies, regardless of where the clouds were in the sky.     

UV Index on tilted surfaces

Solar ultraviolet erythemal irradiance (UVER) has been studied on inclined planes with different orientations in Valencia, Spain. To do this a platform was designed that could turn through 90 degrees on its own axis. The radiometers were inclined at an angle close to the latitude of Valencia (39.5 degrees N). Using two timers the platform could be turned through 90 degrees every 5 min. On clear or partially cloudy days, including those with different turbidity values, it was observed that the UVER showed a maximum at 1200 h GMT, very close to solar noon, in the north and south positions, while the maximum for east and west orientations was found at approximately one hour before and one hour after midday respectively. It was also observed how the irradiance for the south orientation was greater and for the north was less than for the horizontal plane, as well as the opposite performances of the east and west orientations, for four days close to the summer and winter solstices and each equinox. Some experimental results were also compared with the results from the SMARTS2.9 model for the same conditions. It was found that the model frequently overestimated the experimental data. With respect to the maximum calculated UV Index in the different planes this was always higher for the south orientation than for the north, while it was similar for east and west orientations throughout the year. Finally the accumulated erythemal dosage for the considered period was obtained as a function of phototype and orientation, confirming that the accumulated erythemal dosage decreased by around 37% in the north orientation compared to the horizontal value, while in the south position it was only 6% less and some 20% and 15% less in the east and west positions, respectively.     

Polypeptide friction and adhesion on hydrophobic and hydrophilic surfaces: a molecular dynamics case study

Using all-atomistic MD simulations including explicit water, the mobility and adhesion of a mildly hydrophobic single polypeptide chain adsorbed on hydrophobic and hydrophilic diamond surfaces is investigated by application of lateral and vertical pulling forces. Forced motion on the hydrophilic surface exhibits stick-slip due to breaking and reformation of hydrogen bonds; in contrast, on the hydrophobic surface, the motion is smooth. By carefully tuning the driving force magnitude, the linear-response regime is reached on a hydrophobic surface and equilibrium values for mobility and adhesive strength are obtained. On the hydrophilic surface, on the other hand, slow hydrogen-bond kinetics prevents equilibration and only upper bounds for adhesion force and mobility can be estimated. Whereas the desorption force is rather comparable on the two surfaces and differs at most by a factor of 2, the mobility on the hydrophilic surface is at least 30-fold reduced compared to the hydrophobic one. A simple model based on a single particle diffusing in a corrugated potential landscape suggests that cooperativity is rather limited and that the small mobility on a hydrophilic surface can be rationalized in terms of incoherently moving monomers. The experimentally well-known peptide mobility in bulk water is quantitatively reproduced in our simulations, which serves as a sensitive test on our methodology employed.     

Trends in UV irradiance of tanning devices in Norway: 1983-2005

Abstract Indoor tanning increases skin cancer risk, but the importance of different parts of the UV spectrum is unclear. We assessed irradiance of tanning devices in Norway for the period 1983-2005. Since 1983, all tanning models needed approval before being sold or used. UV Type 3 limits were valid from late 1992 (<0.15 W m(-2) for CIE-weighted, i.e. erythemally weighted, short and long wave irradiances). We analyzed data from 90% of the approved tanning models (n = 446 models) and two large inspection surveys in 1998/1999 and 2003 (n = 1341 tanning devices). Mean CIE-weighted short wave irradiance of approved models increased from 0.050 W m(-2) (95% confidence interval [CI] 0.045-0.055) in 1983-1992 to 0.101 W m(-2) (95% CI 0.098-0.105) in 1993-2005, and mean long wave from 0.091 W m(-2) (95% CI 0.088-0.095) to 0.112 W m(-2) (95% CI 0.109-0.115), respectively. Inspection surveys revealed short wave irradiances much higher than that approved. In 1998-1999, only 28% (293/1034) of the devices were equipped with correct sunlamps and only 1 out of 130 inspected establishments fulfilled all requirements. In 2003, corresponding numbers were 59% (180/307) of devices and 2 out of 52 establishments. Mean short and long wave irradiances of the inspected tanning devices in 2003 were 1.5 and 3.5 times, respectively, higher than the irradiance of natural summer sun in Oslo. In conclusion, the short wave irradiance has increased in indoor tanning devices in Norway over the last 20 years. Due to the high long wave irradiance throughout this period, the percentage of short wave irradiance was much lower than for natural sun.     

UV cross-linking of unmodified DNA on glass surfaces

The performance of DNA microarrays strongly depends on their surface properties. Furthermore, the immobilization method of the capture molecules is of importance for the efficiency of the microarray in terms of sensitivity and specificity. This work describes the immobilization of single-stranded capture oligonucleotides by UV cross-linking on silanated (amino and epoxy) glass surfaces. Thereby we used amino (NH₂) and poly thymine/poly cytosine modifications of the capture sequences as well as unmodified capture molecules. The results were compared to UV cross-linking of the same DNA oligonucleotides on unmodified glass surfaces. Immobilization and hybridization efficiency was demonstrated by fluorescence and enzyme-induced deposition of silver nanoparticles. We found out that single-stranded DNA molecules do not require a special modification to immobilize them by UV cross-linking on epoxy- or amino-modified glass surfaces. However, higher binding rates can be achieved when using amino-modified oligonucleotides on an epoxy surface. The limit of detection for the used settings was 5 pM.     

Spectral and chromatographic study of the effect of UV preirradiation on the biodegradation of phenols

The effect of UV radiation of a KrCl excilamp on the biodegradation of 4-nitrophenol, 2,5-dinitrophenol, and their mixture by a Penicillium tardum H-2 isolate strain and microbiocenosis of activated sludge was studied. It was shown that the efficiency of the successive photodegradation and biodegradation of nitrophenols depended on the initial concentration and the time of UV preirradiation. UV irradiation increased the efficiency of the biodegradation of 2,5-dinitrophenol with respect to the biodegradation alone. Preliminary UV irradiation inhibited the subsequent biodegradation of 4-nitrophenol by a Penicillium tardum H-2 isolate strain and activated sludge.     

TFTBD缩氨基硫脲的UV光谱研究

测定了由4，4，4-三氟-1-(2-噻吩基)-1，3-丁二酮(TFTBD)与氨基硫脲反应所形成新席夫碱4，4，4-三氟-1-(2-噻吩基)-1-丁酮-3-缩氨基硫脲(P)的UV光谱，讨论了不同溶剂对P的UV光谱的影响。     

A Web-based tool for UV irradiance data: predictions for European and Southeast Asian sites

There are a range of UV models available, but one needs significant pre-existing knowledge and experience in order to be able to use them. In this article a comparatively simple Web-based model developed for the SoDa (Integration and Exploitation of Networked Solar Radiation Databases for Environment Monitoring) project is presented. This is a clear-sky model with modifications for cloud effects. To determine if the model produces realistic UV data the output is compared with 1 year sets of hourly measurements at sites in the United Kingdom and Thailand. The accuracy of the output depends on the input, but reasonable results were obtained with the use of the default database inputs and improved when pyranometer instead of modeled data provided the global radiation input needed to estimate the UV. The average modeled values of UV for the UK site were found to be within 10% of measurements. For the tropical sites in Thailand the average modeled values were within 1120% of measurements for the four sites with the use of the default SoDa database values. These results improved when pyranometer data and TOMS ozone data from 2002 replaced the standard SoDa database values, reducing the error range for all four sites to less than 15%.     

Liquid drops on vertical and inclined surfaces; I. An experimental study of drop geometry

Experiments have been conducted to investigate the geometric parameters necessary to describe the shapes of liquid drops on vertical and inclined plane surfaces. Two liquids and eight surfaces have been used to study contact angles, contact lines, profiles, and volumes of drops of different sizes for a range of surface conditions. The results show the contact-angle variation along the circumference of a drop to be best fit by a third-degree polynomial in the azimuthal angle. This contact-angle function is expressed in terms of the maximum and minimum contact angles of the drop, which are determined for various conditions. The maximum contact angle, thetamax, is approximately equal to the advancing contact angle, thetaA, of the liquid on the surface. As the Bond number, Bo, increases from 0 to a maximum, the minimum contact angle, thetamin, decreases almost linearly from the advancing to the receding angle. A general relation is found between thetamin/thetaA and Bo for different liquid-surface combinations. The drop contour can be described by an ellipse, with the aspect ratio increasing with Bo. These experimental results are valuable in modeling drop shape, as presented in Part II of this work.     

稀土离子（Ⅲ）与牛血清白蛋白作用的紫外光谱

用紫外光谱研究了稀土离子（Ⅲ）与牛血清白蛋白（BSA）的作用．14种稀土离子均使BSA～280um特征吸收峰强增加，诱导BSA构象发生改变．紫外差谱结果表明，只有氧原子参加与稀土配位．BSA与稀土配位基团为亲水外壳的氨基酸波基和肽键上的C＝O基团．     

Spectral study of a new dihydroisocoumarin

A novel dihydroisocoumarin, 3,4‐dihydro‐6,8‐dihydroxy‐3‐(2′‐acetyl‐3′‐hydroxy‐5′‐methoxy)methyl‐1H‐[2]benzopyran‐1‐one, was isolated from the chloroform extract of the sap of the traditional herb Aloe vera. Its structure was determined by high‐resolution negative fast atom bombardment mass spectrometry (MS), 2D NMR spectroscopy and x‐ray crystallography. The molecular structure was elucidated by 2D NMR analysis. The complete assignment of the ¹H and ¹³C NMR spectra of this compound was performed by using ¹H detected one‐bond heteronuclear multiple quantum correlation (HMQC) and long‐range (two and three bonds) heteronuclear multiple quantum bond correlation (HMBC) experiments. Detailed analyses of the one‐ and two‐dimensional NMR techniques are presented in additional to the spectral properties (MS, IR and UV). Copyright © 2003 John Wiley & Sons, Ltd.     

Assembly of copolymer blend on nanopatterned surfaces: a molecular simulation study

We report a molecular simulation study on the assembly of an (A7B5)5/A7B5 copolymer blend on nanopatterned surfaces. The density distributions, anisotropic radii of gyration, and conformations of both copolymers are quantitatively characterized. As the width of stripes on the surface decreases, the shape and thickness of the assembled film are found to be in qualitative agreement with those from experiments. The simulation results indicate that the shape and conformation of ordered film can be modulated by tuning the adsorption energy between the surface and the polymer or by adjusting the width of the stripes on the surface. We can regulate the width of the stripes to obtain a desired polymer conformation without altering the assembled film. In remarkable contrast to the pure copolymer, the radii of gyration of the blend in three directions are consistently smaller. The simulation reveals that the addition of a short chain during assembly is of central importance in restructuring the conformations of the long chain.     

Adsorption of atoms on cu surfaces: a density functional theory study

The chemisorption of atoms (H, N, S, O, and C) on Cu surfaces has been systematically studied by the density functional theory generalized gradient approximation method with the slab model. Our calculated results indicate that the orders of the adsorption energy are H < N < S < O < C on Cu(111) and H < N < O < S < C on Cu(110) and Cu(100). Furthermore, the adsorption energies of the given atoms on Cu(100) are larger than those on Cu(111) and Cu(110). The preferred adsorption sites are a 3-fold hollow site on Cu(111) and a 4-fold hollow site on Cu(100), but the preferred adsorption sites on Cu(110) are different for different adatoms. The energy, as well as the geometry, is in good agreement with the experimental and other theoretical data. In addition, this study focuses on the electronic and geometric properties of the metal-atom (M-A) bond to explain the difference in adsorption energies among adatoms. A detailed investigation of the density of states curves explains the nature of the most stable site. Finally, we test the effect of the coverage and find that the surface coverage has no influence on the preferred adsorption sites of the given adatoms on Cu(110) with the exception of hydrogen and oxygen, but has much influence on the value of the adsorption energy.     

C-N coupling on transition metal surfaces: a density functional theory study

We have investigated the formation of C-N bonds from individual atoms and single hydrogenated moieties on a series of transition metals. These reactions play a role in HCN formation at high oxygen coverage, also known as Andrussow oxidation, and they are fundamental to understand the ability of other materials to form part of alloys where Pt is the major component. Dehydrogenations take place quite easily under these high oxygen conditions and thus, the C+N, HC+N, and N+CH recombinations to form HCN or its isomer CNH might represent the rate-limiting steps for the reaction. For all the metals in the present study we have found that the activation energy for the reactions between H(x)C and NH(y) (x,y = 0,1) involved in C-N formation follow a linear relationship with the adsorption energy of the N atom. This is due to the common nature of all these transition states, where N-containing fragments get activated from three-fold hollow sites to bridge positions. The slopes of the linear dependence, though, depend on the valence of the N fragment, i.e., smaller slopes are found for NH moieties with respect to N ones.     

Fullerene-containing polymers: UV spectroscopic study

A spectral method is developed to determine the content of fullerene in polymers formed in its presence during the free-radical polymerization and copolymerization of methyl methacrylate, allyl methacrylate, allyl chloride, and styrene. The method is based on measurement of absorption coefficients for the ?Ц?*-excited transition of fullerene cores at 330 nm that is due to their insertion into a polymer chain and the related distortion of the closed polyene system of carbon-carbon bonds.     

Albedo-enhanced maximum UV irradiance--measured on surfaces oriented normal to the sun

UV radiation measured on normal-to-the-sun-oriented surfaces can show significantly higher global UV irradiance values compared to measurements on horizontal receivers. The direct component is amplified by the inverse cosine of the zenith angle, but over surfaces with high local albedo this accounts for only about half of the signal rise of global irradiance. The signal rise of the diffuse component, however, is strongly related to local albedo and solar elevation, which is demonstrated by 2 years of measurements of direct, diffuse, global, reflected and global normal-to-the-sun erythemal effective UV irradiance (UVery). Global UVery signal rises, on normal-to-the-sun-oriented versus horizontal receivers, of up to 65% were measured on fresh snow and solar elevation angles below 30 degrees. An empirical expression has been deduced from the measurements relating the ratio of normal-to-the-sun versus horizontal measurements of global UVery to surface albedo and solar elevation. This allows one to calculate the maximum global UVery irradiance levels which are to be expected on normal-to-the-sun-oriented surfaces with respect to horizontal measurements or model calculations.     

Masterless soft lithography: patterning UV/ozone-induced adhesion on poly(dimethylsiloxane) surfaces

A novel microreactor-based photomask capable of effecting high resolution, large area patterning of UV/ozone (UVO) treatments of poly(dimethylsiloxane) (PDMS) surfaces is described. This tool forms the basis of two new soft lithographic patterning techniques that significantly extend the design rules of decal transfer lithography (DTL). The first technique, photodefined cohesive mechanical failure, fuses the design rules of photolithography with the contact-based adhesive transfer of PDMS in DTL. In a second powerful variation, the UVO masks described in this work enable a masterless soft lithographic patterning process. This latter method, UVO-patterned adhesive transfer, allows the direct transfer of PDMS-based polymer microstructures from a slab of polymer to silicon and other material surfaces. Both methods exploit the improved process qualities that result from the use of a deuterium discharge lamp to affect the UVO treatment to pattern complex, large area PDMS patterns with limiting feature sizes extending well below 1 microm (> or = 0.3 microm). The use of these structures as resists is demonstrated for the patterning of metal thin films. A time-of-flight secondary ion mass spectroscopy study of the process provides new insights into the mechanisms that contribute to the chemistry responsible for the interfacial adhesion of DTL transfers.     

PAR and UV effects on vertical migration and photosynthesis in Euglena gracilis

Recently it was shown that the unicellular flagellate Euglena gracilis changes the sign of gravitaxis from negative to positive upon excessive radiation. This sign change persists in a cell culture for hours even if subsequently transferred to dim light. To test the ecological relevance of this behavior, a vertical column experiment was performed (max. depth 65 cm) to test distribution, photosynthetic efficiency and motility in different horizons of the column (surface, 20, 40 and 65 cm). One column was covered with a UV cut-off filter, which transmits photosynthetically active radiation (PAR) only, the other with a filter which transmits PAR and UV. The columns were irradiated with a solar simulator (PAR 162 W m(-2), UV-A 32.6 W m(-2), UV-B 1.9 W m(-2)). The experiment was conducted for 10 days, normally with a light/dim light cycle of 12 h:12 h, but in some cases the light regime was changed (dim light instead of full radiation). Under irradiation the largest fraction of cells was found at the bottom of the column. The cell density decreased toward the surface. Photosynthetic efficiency, determined with a pulse amplitude modulated fluorometer, was negligible at the surface and increased toward the bottom. While the cell suspension showed a positive gravitaxis at the bottom, the cells in the 40 cm horizon were bimodally oriented (about the same percentage of cells swimming upward and downward, respectively). At 20 cm and at the surface the cells showed negative gravitaxis. Positive gravitaxis was more pronounced in the UV + PAR samples. At the surface and in the 20 and 40 cm horizons photosynthetic efficiency was better in the PAR-only samples than in the PAR + UV samples. At the bottom photosynthetic efficiency was similar in both light treatments. The data suggest that high light reverses gravitaxis of the cells, so that they move downward in the water column. At the bottom the light intensity is lower (attenuation of the water column and self shading of the cells) and the cells recover. After recovery the cells swim upward again until the negative gravitaxis is reversed again.     

Particle zips: vertical emulsion films with particle monolayers at their surfaces

Vertical emulsion films with particle monolayers at their surfaces have been studied by direct microscope observations. The effects of particle wettability and surface coverage on the structure and stability of water films in octane and octane films in water have been investigated. Monodisperse silica particles (3 microm in diameter) hydrophobized to different extents have been used. It is found that the structure and stability of emulsion films strongly depend on the film type (water-in-oil or oil-in-water), the particle contact angle, the interactions between particles from the same and the opposite monolayer, and the monolayer density. Stable films are observed only when the particle wettability fulfills the condition for stable particle bridges--in agreement with the concept that hydrophilic particles can give stable oil-in-water emulsions, whereas hydrophobic ones give water-in-oil emulsions. In the case of water films with dilute disordered monolayers at their surfaces, the hydrophilic particles are expelled from the film center toward its periphery, giving a dimple surrounded by a ring of particles bridging the film surfaces. In contrast, the thinning of octane films with dilute ordered monolayers at their surfaces finally leads to the spontaneous formation of a dense crystalline monolayer of hydrophobic particles bridging both surfaces at the center of the film. The behaviors of water and octane films with dense close-packed particle monolayers at their surfaces are very similar. In both cases, a transition from bilayer to bridging monolayer is observed at rather low capillary pressures. The implications of the above finding for particle stabilized emulsions are discussed.