Synopsis Microfine titanium dioxide (TiO2) has become a frequently used physical UV filter in sunscreen formulations. Penetration of microfine TiO2 into human skin seems to be possible because of the mean particle size of 20 nm. The small particle size results in a high surface activity of the primary particles and causes a formation of agglomerates in the formulation. The aim of this study was to investigate the in vivo and in vitro penetration behaviour of the physical UV filter into human skin. Furthermore, a stable sunscreen formulation with microfine TiO2 which does not penetrate into the skin should be developed. According to our experiments, microfine TiO2 penetrates deeper into human skin from an oily dispersion than from an aqueous one. Therefore, an o/w emulsion containing the dispersed micropigment in the aqueous phase was manufactured. Microfine TiO2 cannot penetrate into human skin from this emulsion, but the storage stability of the formulation is very low at different temperatures. The encapsulation of the micropigment into liposomes does not result in a better stability but it causes a higher penetration depth of the particles into the skin. Résumé Le dioxyde de titane microfin est devenu un filtre UV physique très fréquemment utilisé dans les crèmes solaires. Une pénétration de dioxyde de titane microfin dans la peau humaine est rendu possible grâce sa granulométrie moyenne de 20 nm. Mais la taille des particules entraîne une activité de surface anormalement élevée, ce qui génère la formation d’agglomérats dans la formulation. L’objet des travaux présentés ici était l’étude de la pénétration du filtre UV physique dans la peau humaine, in vivo et in vitro. En outre, une crème solaire à base de dioxyde de titane microfin, ne pénétrant pas dans la peau, devait être développée. Selon nos investigations, le dioxyde de titane microfin pénètre plus profondément dans la peau à partir d’une dispersion huileuse que d’une dispersion aqueuse. Par conséquent, une émulsion de type huile dans eau (h/e), avec le micropigment dispersé dans la phase aqueuse, a èté réalisée. Il en ressort que le dioxyde de titane ne pénètre pas dans la peau à partir de l’émulsion h/e, mais la stabilité de l’émulsion à différentes température est très limitée. L’encapsulation du micropigment dans des liposomes n’entraîne pas d’amélioration de la stabilité mais génère une pénétration plus importante des particules dans la peau.
Rutherford backscattering spectroscopy (RBS) has been used during the development of multilayer thin film optical filters, especially designed for the fluorescence detector of the Pierre AUGER Project. Depth profiles of the heavy components have been measured directly, while reliable results for the light components could also be extracted indirectly. Relative thickness and density of the individual layers and deviations from the desired thickness and stoichiometry have been deduced. The findings of the RBS method have been compared and discussed with results obtained by other characterization techniques.
A method for fabrication of ultraviolet induce transmission(IT) filter by visible light control in an ordinary vacuum is presented.Manufacturing principles and techniques are disscussed.Measured spectral transmittance curves of making ultraviolet IT filter by this method are given.
We present results concerning the development and calibration of a new set of narrowband comet filters, designated the HB filter set, which was designed and manufactured to replace aging IHW filters. Information is also presented about the design and manufacturing of the filters, including the reasoning that was used for deciding the final wavelengths and bandpasses. The new filters are designed to measure five different gas species (OH, NH, CN, C2, C3), two ions (CO+, H2O+), and four continuum points. An improved understanding of extended wings from emission bands in comet spectra, gained since the development of the IHW filters, was incorporated into the new design, so that contamination from undesired species is significantly reduced compared to previous filters. In addition, advances in manufacturing techniques lead to squarer transmission profiles, higher peak transmission and UV filters with longer lifetimes.We performed the necessary calibrations so that data obtained with the filters can be converted to absolute fluxes, allowing for, among other things, accurate subtraction of the continuum from the gas species. Flux standards and solar analogs were selected and observed, and the data were used to establish a magnitude system for the HB filters. The star measurements were also used to evaluate which solar analogs were best representatives of the Sun and to explore how the flux standards differed in the UV with respect to their spectral type. New procedures were developed to account for the non-linear extinction in the OH filter, so that proper extrapolations to zero airmass can be performed, and a new formalism, which can account for mutual contaminations in two (or more) filters, was developed for reducing comet observations. The relevant equations and reduction coefficients are given, along with detailed instructions on how to apply them. We also performed a series of tests involving factors that can affect either the filter transmission profiles or the distribution of the emission lines in the gas species to determine how these effects propagate through to the calibration coefficients. The results indicate that there are only two factors that are a concern at a level of more than a few percent: f-ratios smaller than f/4, and a few individual filters whose transmission profiles are significantly different from the filters used in the calibrations. Copyright 2000 Academic Press.
Experimental results are reported on a mobile, stand-alone, solarblind ultraviolet (UV) Raman lidar system for the stand-off detection and identification of liquid and solid targets at ranges of hundreds of meters. The lidar is a coaxial system capable of performing rangeresolved measurements of gases and aerosols, as well as solids and liquids. The transmitter is a flash lamp pumped 30 Hz Nd:YAG laser with quadrupled output at 266 nm. The receiver subsystem is comprised of a 40 cm Cassegrain telescope, a holographic UV edge filter for suppressing the elastic channel, a 0.46 m Czerny-Turner spectrometer, and a time gated intensified charge-coupled device (CCD) detector. The rejection of elastic light scattering by the edge filter is better than one part in 105, while the transmittance 500 cm-1 to the red of the laser line is greater than 50%. Raman data are shown for selected solids, neat liquids, and mixtures down to the level of 1% volume ratio. On the basis of the strength of the Raman returns, a stand-off detection limit of ~500 g/m2 for liquid spills of common solvents at the range of one half of a kilometer is possible.
The manufacturing processes for spectral-sensitive on-chip masking of Si-PIN-diodes using thin-film optical filters are described. As two examples, a diode array with red, green, and blue filters (RGB) and a UV-sensitive diode are explained in detail. The RGB-filters are made of TiO SiO thin-films and the UV-filter is a metal/dielectric multilayer using HfO , SiO , and Al thin-films. Both filter types are self-blocked over a wavelength range from 200 to 1100nm. The optical coatings on the diodes are arranged as pixels with rhombic or rectangular shapes and with a later dimensions of about 20 microns as minimum. The used lift-off technique for patterning the coatings is described briefly. Reactive e-beam evaporation with ion-assistance is used to deposit the optical coatings.
Stratospheric ozone depletion by anthropogenic chlorofluorocarbons has lead to increases in ultraviolet‐B radiation (UV‐B; 280–320 nm) along the Antarctic Peninsula during the austral spring. We manipulated UV‐B levels around plants of Antarctic hair grass (Deschampsia antarctica; Poaceae) and Antarctic pearlwort (Colobanthus quitensis; Caryophyllaceae) for one field season near Palmer Station along the west coast of the Antarctic Peninsula. Treatments involved placing frames over naturally growing plants that either (1) held filters that absorbed most biologically effective radiation (UV‐BBE; ‘reduced UV‐B’, 22% of ambient UV‐BBE levels), (2) held filters that transmitted most UV‐BBE (‘near‐ambient UV‐B’, 87% of ambient UV‐BBE levels), or (3) lacked filters (‘ambient UV‐B’). Leaves on D. antarctica exposed to near‐ambient and ambient UV‐B were 16–17% shorter than those exposed to reduced UV‐B, and this was associated with shorter epidermal cells at the leaf base and tip. Leaves on C. quitensis exposed to near‐ambient and ambient UV‐B tended to be shorter (P=0.18) and epidermal cells at the leaf base tended to be smaller than those under reduced UV‐B (P<0.10). In order to further explain reductions in leaf length, we examined leaf concentrations of insoluble (cell‐wall bound) phenylpropanoids, since it has been proposed that wall‐bound phenylpropanoids such as ferulic acid may constrain cell expansion and leaf elongation. In both species, HPLC analysis revealed that ferulic and p‐coumaric acid were major components of both insoluble and soluble phenylpropanoids. Although there were no significant differences in concentrations between UV‐B treatments, concentrations of insoluble ferulic acid in D. antarctica tended to be higher under ambient and near‐ambient UV‐B than under reduced UV‐B (P=0.17). We also examined bulk‐leaf concentrations of soluble (methanol extractable) UV‐B‐absorbing compounds and found that concentrations were higher in plants exposed to near‐ambient and ambient UV‐B than in plants exposed to reduced UV‐B. We also assessed the UV‐B‐screening effectiveness of leaves that had developed on plants at the field site with a fiber‐optic microprobe. Leaf epidermal transmittance of 300‐nm UV‐B was 4.0 and 0.6% for D. antarctica and C. quitensis, respectively, which is low compared to grasses and herbaceous dicotyledonous plants found in more temperate climates. While the leaves of Antarctic vascular plants are relatively effective at screening UV‐B, levels of UV‐B in Antarctica are sufficient to reduce leaf epidermal cell size and leaf elongation in these species, although the mechanisms for these reductions remain unclear.
This paper reports the application of a previously described i.r. spectrometric method, which measures the evolution of carbon dioxide, and hence the rate of photo-oxidation, caused by UV irradiation of paint films, to a study of the dependence of paint degradation on UV wavelength. Measurements have been made on both unpigmented and TiO2-pigmented acrylic films. Preliminary measurements demonstrate that, for both pigmented and unpigmented acrylic films, the rate of carbon dioxide generation is proportional to I 0.5, the square root of the UV intensity. As the rate of carbon dioxide generation is a measure of paint film degradation, this implies that the rate of film degradation is proportional to the square root of UV intensity. This is the first time that this square root dependence, previously predicted from photo-oxidation studies of model compounds, has been directly measured on a practical paint film. Photo-oxidation of unpigmented, anatase-pigmented and rutile-pigmented acrylic films has been measured by using optical filters to isolated selected portions of the output of a Xenon lamp. Results have been analyzed semi-quantitatively taking into account the measured transmission characteristics of the filters, the lamp output and the I 0.5 relationship. The disproportionate deleterious effects of short wavelength, <300 nm, radiation on unpigmented films have been confirmed and the stability of anatase pigmented films to 405 nm radiation has been demonstrated directly. The FTIR assay of carbon dioxide produced by paint film degradation could be applied to other polymer films and combined with measurements of carbonyl band development.