Colloids of TiO2, where rutile was the only crystal modification which could be detected, with ca. 2.5 nm average particle diameter were synthesized by hydrolysis of TiCl4 in acidic solutions. The as-prepared particles were incorporated in polymers such as poly(vinyl alcohol) (PVAL), partially hydrolyzed poly(vinyl acetate) (PVAC88), polyvinylpyrrolidone, and poly(4-vinylpyridine). Nanocomposites transparent in the visible range were obtained. The highest TiO2 contents in such materials were achieved with PVAL and PVAC88, with TiO2 contents of ca. 35 wt.-% (i.e. 10.5 vol.-%). In particular, the nanocomposites with TiO2 contents above 24 wt.-% acted as efficient UV filters for radiation UP to ca. 360 nm. At very low TiO2 contents, an absorption maximum of the embedded TiO2 particles was observed at 225, ran with an extinction coefficient of 140 000 cm(-1) and a full width at half maximum of 45 nm, i.e. not only the absorption at the maximum at 225 nm but also at the flank of this band contributed significantly to the broadband UV absorption in the nanocomposites at higher TiO2 fractions. The incorporation of TiO2 enhanced the refractive index of the nanocomposites: for instance a refractive index of 1.609 was measured for a nanocomposite comprising 10.5 vol.-% TiO2 in PVAL, compared with 1.521 for the pristine polymer.
The fact that certain ultraviolet (UV) filters used in cosmetics display estrogenic activity prompted us to study potential actions on androgen receptors (AR) in the human breast carcinoma cell line MDA-kb2, which expresses functional endogenous AR and glucocorticoid receptors (GR) and is stably transfected with a luciferase reporter plasmid. Dihydrotestosterone (DHT), methyltrienolone (R1881), methyltestosterone, danazol, and androstenedione increased luciferase activity, with EC50 values between 0.11 nM (R1881), 0.14 nM (DHT), and 73.5 nM (androstenedione). DHT-induced luciferase gene expression was inhibited by nonsteroidal antiandrogens, hydroxyflutamide, flutamide, bicalutamide, and vinclozolin. In contrast, the steroidal AR agonist/antagonist cyproterone actetate showed agonistic activity in the absence and presence of DHT, which was not blocked by hydroxyflutamide and thus seems not to be mediated by AR. GR-mediated activation of luciferase by dexamethasone was 100 times less potent than DHT and was not antagonized by hydroxyflutamide. The cell line was used for screening of UV filters, benzophenone-3 (Bp-3), benzophenone-4, 3-benzylidene camphor, 4-methylbenzylidene camphor, butyl-methoxy-dibenzoylmethane, homosalate (HMS), octyl-dimethyl-PABA, and octyl-methoxycinnamate. Two of these, Bp-3 and HMS, antagonized DHT-induced AR activation below cytotoxic concentrations, with IC50 of 5.57 10(-6) M (HMS) and 4.98 10(-6) M (Bp-3). None of the eight UV filters displayed agonistic activity when tested alone, but high concentrations of Bp-3 induced an increase of luciferase activity in the presence of dexamethasone, which was not blocked by hydroxyflutamide or the estrogen antagonist, ICI 182,780. These data indicate that the UV filters Bp-3 and HMS possess antiandrogenic activity in vitro in addition to estrogenic activity.
Microemulsion electrokinetic chromatography (MEEKC) has been applied to the separation of some UV filters (Eusolex 4360, Eusolex 6300, Eusolex OCR, Eusolex 2292, Eusolex 6007, Eusolex 9020, Eusolex HMS, Eusolex OS, and Eusolex 232) commonly used in sunscreen lotions. Use of a MEEKC buffer with a mixed surfactant system to stabilize the oil droplets and an organic modifier in the aqueous phase allowed separation of most of the selected analytes in a single run in a system fitted with a diode array detector recording three wavelengths (240 nm, 300 nm, and 380 nm) simultaneously. The microemulsion employed consisted of 2.25 g of SDS, 0.75 g of Brij 35, 6.6 g 1-butanol, 0.8 g n-octane, 17.5 g 2-propanol, and 72.1 g of 10 mM borate buffer (pH 9.2). Detection limits from 0.65 to 6.0 mug/mL were obtained and the calibration plots were linear over at least one order of magnitude for all analytes. The developed method could be applied to the determination of UV filters in several sun protection products including lotions, milks, and oils. Comparison of the obtained data with those from an HPLC method described in the literature showed acceptable agreement.
A set of 48 ultraviolet-visible filters in the Wide Field Camera 3 will be deployed on the Hubble Space Telescope in 2004. We summarize the specifications for the filters, derived through interaction with the Science Oversight Committee. A detailed characterization of the 48 filters is presented.
The Extreme Universe Space Observatory (EUSO) is an international program recently approved by ESA for accommodation on the International Space Station. The aim of this telescope is to detect the very rare ultra-high-energy cosmic ray events looking downward the Earth atmosphere from the Space Station. The interaction between these cosmic rays and nitrogen molecules in the atmosphere produces fluorescence radiation in the ultraviolet, in the region ranging from 300 nm up to 400 nm. This radiation is collected by Fresnel lenses onto a focal plane detector composed of about 5000 Multi-Anodes Photomultiplier tubes (MAPMT) providing 2 × 10 4-mm pixels. The phase A of this complex program started in March 2002 and it will last one year. During this period the MAPMTs will be fully tested and characterized in the UV region of interest and the focal plane architecture will be designed taking into account the constraints given by the optical design and the results from tests. The test measurements will give information on the response, by changing parameters such as the incidence angle, the gain, the dinode biasing. Ageing effects will be also evaluated. This paper reports on the results of UV measurements on MAPMT obtained at the INFN in Florence, Italy, and it presents the concept study of the UV filter system and the evaluation of a new compact light collector/filter device to be coupled with the detector.
UV-SPRAFIMO is a completely new developed UV instrument for very fast measurements of solar spectral irradiance with high spectral resolution and arbitrary step width. It combines sophisticated filter radiometer technique with a new model based on neural networks. UV-SPRAFIMO has the following specifications: (1) Spectral region 280 - 400 nm. (2) Arbitrary spectral resolution and step width of the UV spectra (≥ 0.05 nm). (3) Simultaneous measurement of all spectral channels. (4) Up to 5 measurements per second with arbitrary averaging interval of 5 to 30 seconds. (5) Weatherproofed, air conditioned housing and fully automatic measurement system. (6) No moving parts. (7) Data logger up to 64 Mbytes memory for long-term measurements at remote sites. (8) GPS to automatically set up time and geographical position data. (9) PC based, graphical user interface for measurement set up and monitoring and processing of data. (10) Online calculation and visualization of integrated irradiances like UV-A, UV-B and UV-Index as well as erythemal or user defined weighted irradiance. (11) Simultaneous total ozone column retrieval from spectral measurements. UV-SPRAFIMO is a standalone and easy to use UV spectral radiometer; it was tested in different climate regions during field measurement campaigns in order to compare measurement performance and accuracy to high quality scanning spectral radiometers. Details of functional principles and results of the measurement campaigns are presented.
NILU has developed an accurate, reliable and robust filter instrument for measuring irradiances at ultraviolet (UV) and visible wavelengths. The NILU-UV instrument has been thoroughly tested through comparisons with well calibrated spectral radiometers over extended time periods with significant variations in ozone and cloud cover. The objective of this work is to present the instrument and to derive UV doses, total ozone abundances and cloud effects from the NILU-UV instrument, and compare the results with similar results from a double monochromator Bentham spectroradiometer and a Brewer ozone spectrophotometer.