Home About us Contact
|
Home About us Contact | ||
|
|
||
UV Light (uv + light)
Terms modified by UV Light Selected AbstractsPt immobilization on TiO2 -embedded carbon nanofibers using photodepositionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2010S. Kim Abstract Currently, the use of fuel cell electrodes containing Pt catalysts has been limited due to technological problems in this system, primarily the system's high cost. The improvement of Pt catalyst use has been achieved by changes in the Pt immobilization method. In this study, we have studied Pt immobilization on carbon nanofiber composites using the photodeposition method. First, we prepared the carbon nanofibers, which were homogeneously embedded TiO2 using the electrospinning technology. These TiO2 -embedded carbon nanofiber composites (TiO2/CNFs) were then immersed in a Pt precursor solution and irradiated with UV light. The obtained Pt-deposited TiO2/CNFs contained Pt that was immobilized on the carbon nanofibers, and the Pt particle size was 2-5 nm. The XPS spectra showed that the amount of Pt increased with an increasing UV irradiation time. The current densities and total charge also increased with an increase in the UV irradiation time, possibly due to an increase of active specific area by finely dispersed Pt nanoparticles. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microaffinity purification of proteins based on photolytic elution: Toward an efficient microbead affinity chromatography on a chipELECTROPHORESIS, Issue 3 2005Woo-Jae Chung Abstract A bead affinity chromatography system, which was based on the photolytic elution method, was integrated into a glass-silicon microchip to purify specific target proteins. CutiCore® beads, which were coupled with a photo-cleavable ligand, such as biotin and an RNA aptamer, were introduced into a filter chamber in the microchip. The protein mixture containing target protein labeled with fluorescein isothiocyanate (FITC) was then passed through the packed affinity beads in the microchamber by pressure-driven flow. During the process, the adsorbed protein on the bead was monitored by fluorescence. The concentrated target protein on the affinity bead was released by simple irradiation with UV light at a wavelength of 360 nm, and subsequently eluted with the phosphate buffer flow. The eluted target protein was quantitatively detected via the fluorescence intensity measurements at the downstream of the capillary connected to the outlet of the microchip. The microaffinity purification allowed for a successful method for the identification of specific target proteins from a protein mixture. In addition, the feasibility of this system for use as a diagnosis chip was demonstrated. [source] Photocatalytic oxidation of methanol using silica-titania composites in a packed-bed reactorENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2006Jennifer M. Stokke Abstract The processing of forest products into pulp, paper, paperboard, and other wood products results in the generation of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). This work focused on the development of a photocatalytic packed-bed reactor for the oxidation of methanol, which is the primary constituent in high volume low concentration gases emitted from pulp and paper mills. Bench-scale studies using an annular reactor packed with silica-titania composite (STC) pellets were conducted to maximize methanol removal and minimize the formation of byproducts, such as formaldehyde. Parameters such as STC pore size (ca. 40, 120, and 260 Å) and UV wavelength (UVA and UVC) were varied. In the dark, the STC pellets removed methanol via adsorption and had a finite adsorption capacity dependent on the surface area of the composite. When irradiated with UV light, the STC pellets adsorbed and oxidized methanol simultaneously. At the bench-scale, 40 Å STC pellets irradiated with UVC light achieved the greatest methanol removal (ca. 90%) with minimal byproduct formation (i.e., effluent formaldehyde concentration was <1 ppmv). Based on these results, a 40 acfm pilot reactor was fabricated and achieved methanol removal rates up to 66% ± 7% with <1 ppmv formaldehyde production at steady state. © 2006 American Institute of Chemical Engineers Environ Prog, 2006 [source] Spatiotemporal properties of cytoplasmic cyclic AMP gradients can alter the turning behaviour of neuronal growth conesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2004Sebastian Munck Abstract Growth cones, the terminal structures of elongating neurites, use extracellular guidance information in order to navigate to appropriate target cells. The directional information of guidance cues is transduced to a cytoplasmic gradient of messenger molecules across the growth cone leading to rearrangements of the cytoskeleton. One messenger molecule regulating growth cone turning is cAMP, which is also known to be sufficient to direct growth cone attraction. Cytoplasmic cAMP gradients have been generated in the present study by photolysing caged cAMP with UV light focused on one side of growth cones of chick sensory neurons. Using this method we show that only specific time patterns of pulsed cAMP release are capable of inducing growth cone turning whereas others, which release the same amount of cAMP, are ineffective. Theoretical calculations show that diverse time patterns produce different intracellular gradients, which were visualized directly in HeLa cells expressing cAMP-sensitive ion channels as a reporter system. Together these data indicate that the spatiotemporal properties of the intracellular gradient are crucial for growth cone turning. [source] Intramolecular Opening of ,-Lactams with Amines as a Strategy Toward Enzymatically or Photochemically Triggered Activation of Lactenediyne ProdrugsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2003Luca Banfi Abstract In order to develop a general strategy for selective activation of designed enediyne prodrugs belonging to the "lactenediyne" family, we studied the scope of intramolecular transamidation of simple monocyclic ,-lactams bearing a tethered amine. The effect of substituents, of reaction media, and of the type of tether, on the rate of transamidation is disclosed. The possibility of triggering the transamidation event under mild conditions by the action of suitable enzymes or UV light was demonstrated on model monocyclic ,-lactams. Finally, the strategy of intramolecular opening of the ,-lactam leading to a larger seven-membered ring was employed on a lactenediyne, demonstrating that ring enlargement could unleash the reactivity of the enediyne moiety. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Multifunctional Au-Coated TiO2 Nanotube Arrays as Recyclable SERS Substrates for Multifold Organic Pollutants DetectionADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Xuanhua Li Abstract A multifunctional Au-coated TiO2 nanotube array is made via synthesis of a TiO2 nanotube array through a ZnO template, followed by deposition of Au particles onto the TiO2 surface using photocatalytic deposition and a hydrothermal method, respectively. Such arrays exhibit superior detection sensitivity with high reproducibility and stability. In addition, due to possessing stable catalytic properties, the arrays can clean themselves by photocatalytic degradation of target molecules adsorbed to the substrate under irradiation with UV light into inorganic small molecules using surface-enhanced Raman spectroscopy (SERS) detection, so that recycling can be achieved. Finally, by detection of Rhodamine 6G (R6G) dye, herbicide 4-chlorophenol (4-CP), persistent organic pollutant (POP) dichlorophenoxyacetic acid (2,4-D), and organophosphate pesticide methyl-parathion (MP), the unique recyclable properties indicate a new route in eliminating the single-use problem of traditional SERS substrates and show promising applications for detecting other organic pollutants. [source] Loss-of-function variants of the human melanocortin-1 receptor gene in melanoma cells define structural determinants of receptor functionFEBS JOURNAL, Issue 24 2002Jesús Sánchez Más The ,-melanocyte-stimulating hormone (,MSH) receptor (MC1R) is a major determinant of mammalian skin and hair pigmentation. Binding of ,MSH to MC1R in human melanocytes stimulates cell proliferation and synthesis of photoprotective eumelanin pigments. Certain MC1R alleles have been associated with increased risk of melanoma. This can be theoretically considered on two grounds. First, gain-of-function mutations may stimulate proliferation, thus promoting dysplastic lesions. Second, and opposite, loss-of-function mutations may decrease eumelanin contents, and impair protection against the carcinogenic effects of UV light, thus predisposing to skin cancers. To test these possibilities, we sequenced the MC1R gene from seven human melanoma cell (HMC) lines and three giant congenital nevus cell (GCNC) cultures. Four HMC lines and two GCNC cultures contained MC1R allelic variants. These were the known loss-of-function Arg142His and Arg151Cys alleles and a new variant, Leu93Arg. Moreover, impaired response to a superpotent ,MSH analog was demonstrated for the cell line carrying the Leu93Arg allele and for a HMC line homozygous for wild-type MC1R. Functional analysis in heterologous cells stably or transiently expressing this variant demonstrated that Leu93Arg is a loss-of-function mutation abolishing agonist binding. These results, together with site-directed mutagenesis of the vicinal Glu94, demonstrate that the MC1R second transmembrane fragment is critical for agonist binding and maintenance of a resting conformation, whereas the second intracellular loop is essential for coupling to the cAMP system. Therefore, loss-of-function, but not activating MC1R mutations are common in HMC. Their study provides important clues to understand MC1R structure-function relationships. [source] Immunological quantification of the nematode parasitic bacterium Pasteuria penetrans in soilFEMS MICROBIOLOGY ECOLOGY, Issue 3 2001S Fould Abstract Currently, the abundance of Pasteuria penetrans in soils, an unculturable bacterial parasite of root-knot nematodes (Meloidogyne spp.), is estimated by the percentage of nematode juveniles infected with bacteria and the number of spores attached to their cuticle. Indirect immunofluorescence led to detection of free spores directly in soil suspensions using UV light and polyclonal antibodies raised against two P. penetrans populations (ORS-21414-Sen and PP1). Three extraction methods were compared in order to improve spore recovery. A gentle shaking/sieving method recovered more than 90% of the spores inoculated in soils and was more efficient and simple than aqueous two-phase partitioning and polyethylene glycol extractions. All the spores inoculated in sandy or sandy,clay soils were detected with immunofluorescence microscopy. The quantification of the spores was improved using an ELISA technique that showed a good correlation between optical density and spore concentration in inoculated soils. Specific antibodies provide a suitable method to quantify P. penetrans and may be used to follow the evolution of the real pool of bacteria either in native suppressive soils or in inoculated ones. [source] Grayscale Photopatterning of an Amorphous Polymer Thin Film Prepared by Photopolymerization of a Bisanthracene-Functionalized Liquid-Crystalline MonomerADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Hideyuki Kihara Abstract A method for grayscale photopatterning of an amorphous polymer film derived from a bisanthracene-functionalized liquid-crystalline monomer is developed. Solution photopolymerization of a monomer with two anthracene moieties, one at each end, affords an amorphous polymer. A combination of irradiation with patterned UV light and heating results in photopatterning on thin films prepared from the polymer. On non-irradiated areas of the film, the polymer reverts to the monomer owing to the thermal back-reaction of the anthracene photodimer, forming an ordered phase. On irradiated areas remaining in the amorphous phase, the thermal back-reaction is suppressed. This phenomenon results in a clear contrast and visual images on the film under polarized light. Grayscale photopatterning is also made possible for the solution-polymerized polymer by controlling the intensity of exposure. In addition, rewritable photopatterning can be achieved by melt photopolymerization of the monomer. The new photopatterning is essentially nondestructive because it needs neither image development nor anthracene-excitation light for reading. [source] Reversibly Light-Switchable Wettability of Hybrid Organic/Inorganic Surfaces With Dual Micro-/Nanoscale RoughnessADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Gianvito Caputo Abstract Here, an approach to realize "smart" solid substrates that can convert their wetting behavior between extreme states under selective light irradiation conditions is described. Hybrid organic/inorganic surfaces are engineered by exploiting photolithographically tailored SU-8 polymer patterns as templates for accommodating closely packed arrays of colloidal anatase TiO2 nanorods, which are able to respond to UV light by reversibly changing their surface chemistry. The TiO2 -covered SU-8 substrates are characterized by a dual micro-/nanoscale roughness, arising from the overlapping of surfactant-capped inorganic nanorods onto micrometer-sized polymer pillars. Such combined architectural and chemical surface design enables the achievement of UV-driven reversible transitions from a highly hydrophobic to a highly hydrophilic condition, with excursions in water contact angle values larger than 100°. The influence of the geometric and compositional parameters of the hybrid surfaces on their wettability behavior is examined and discussed within the frame of the available theoretical models. [source] Densification of Oxide Nanoparticle Thin Films by Irradiation with Visible LightADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Massimo F. Bertino Abstract A technique is presented that allows for altering of the physical characteristics of films of TiO2 nanoparticles by exposure to visible light. In this technique, dye-sensitized oxide nanoparticles are deposited on a substrate by dip-coating. Photodissociation of the organic ligand layer leads to cross-linking of the nanoparticles. Consequently, irradiated films have a decreased porosity, an increased index of refraction and an increased hydrophobicity. Films irradiated with green light are compared to films irradiated with UV light. Within experimental error, visible- and UV-illumination induces the same changes in the films. The mechanism of surfactant elimination in dye-sensitized oxide particles is discussed, patterning is demonstrated, and prospective applications of the technique are considered. [source] The Influence of UV Irradiation on Ketonic Defect Emission in Fluorene-Based Copolymers,ADVANCED FUNCTIONAL MATERIALS, Issue 17 2008Horst Scheiber Abstract The influence of UV irradiation in inert atmosphere on the emission spectrum of fluorenone containing poly[9,9-bis(2-ethyl)hexylfluorene] (PF2/6) has been investigated by means of optical absorption, photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy. It is shown that a substantial reduction of green emission arising from ketonic defect sites can be achieved by irradiation of thin films with UV light. This is found to be accompanied by partial cross-linking of the films. FTIR measurements show no reduction of the C=O stretching mode upon irradiation, and, moreover, the degree of cross-linking does not scale with the relative fluorenone content (0.1, 0.5, and 5%). Therefore, the reduced emission intensity in the green spectral region is rather associated with the occurrence of interruptions in the polymer backbone, which reduce the effective conjugation length and subsequently inhibit the energy transfer onto the ketonic defect sites. The found results enabled us to build organic light emitting devices (OLEDs) that can be structured by selective illumination of the emitting layer with an intense UV light source. This method allows for the fabrication of rather efficient (2000,cd,m,2 at 7,V) two-color OLEDs. [source] Red,Yellow Fluorescence Patterning of a Polymer Film Containing Phthalimido Carbamate GroupsADVANCED FUNCTIONAL MATERIALS, Issue 17 2007H. Chae Abstract Bicolor fluorescent micro-patterns in the polymer film are prepared through the use of a new group of photobase generator containing phthalimido carbamate groups. The photobase generation from phthalimide carbamates is studied by examining the changes in pH, fluorescence intensity, and photo-crosslinking of poly(glycidyl methacrylate). The product analysis of a model compound indicates that amine groups are produced from the photolytic cleavage of the C,N bond of the phthalimide carbamate groups. A copolymer containing phthalimide carbamate groups is applied to a bicolor fluorescent imaging material. Red-yellow fluorescent micropatterns are obtained by treating the copolymer film, which is irradiated with 254 nm UV light through a photomask, with fluorescamine and rhodamine, consecutively. Various colored fluorescent micropatterns , green, red, or red-yellow, are obtained on a single polymer film by varying the excitation wavelength. [source] UV-Light-Driven Immobilization of Surface-Functionalized Oxide Nanocrystals onto Silicon,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2007E. Fanizza Abstract TiO2 nanorods (NRs) and ,-Fe2O3 nanocrystals (NCs) passivated with unsaturated long-chain carboxylic acids, namely 10-undecylenic acid (10UDA) and oleic acid (OLEA), are covalently anchored to Si(100) at room temperature by UV-light-driven reaction of hydrogenated silicon with the carbon,carbon double bond (,CC,) moieties of the capping surfactants. The high reactivity of vinyl groups towards Si provides a general tool for attaching particles of both materials via Si,C bonds. Interestingly, TiO2 NRs were efficiently attached to silicon even when capped by OLEA. This latter finding has been explained by a photocatalytic mechanism involving the primary role of hydroxyl radicals that can be generated upon bandgap TiO2 photoexcitation with UV light. The increased oxide coverage achievable on Si opens access to further surface manipulation, as demonstrated by the possibility of depositing an additional film of Au nanoparticles onto TiO2 via TiO2 -catalyzed visible-light-driven reduction of aqueous AuCl4, ions. Extensive morphological and chemical characterization of the obtained NC-functionalized Si substrates is provided to support the effectiveness of proposed photochemical approaches. [source] Photogeneration of High Pretilt Angles of Nematic Liquid Crystals by Non-Polarized Light Irradiation of Azobenzene-Containing Polymer Films,ADVANCED FUNCTIONAL MATERIALS, Issue 3 2004S. Furumi Abstract A vertical-alignment (VA) cell of nematic liquid crystals (LCs) was prepared using photoirradiated thin films of a poly(methacrylate) with mesogenic moieties of 4-trifluoromethoxyazobenzene as the side chains. Optical anisotropy was generated by oblique irradiation of the azobenzene-containing polymer films with non-polarized UV light, followed by annealing treatment to enhance the photodichroism, which displayed thermal stability. The combination of oblique exposure to non-polarized UV light and subsequent annealing treatment brought about high pretilt angles of nematic LCs so that a photoaligned VA LC cell was fabricated. The photopatterned LC cell exhibited electro-optical properties with excellent optical quality when a voltage was applied even after heating at 100,°C for several hours. [source] Fading of artificial hair colour and its prevention by photofiltersINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2006B. Locke Fading of artificial hair colour has been investigated by simulating actual usage conditions through exposure to artificial radiation in a weatherometer, with 0.35 mW (m2nm),1 at 340 nm, for 16,48 h, and by periodical washing. Hair colour was produced by using commercial two-part, permanent hair dyes with light auburn, medium auburn and dark auburn shades. Formulations based on red couplers, such as 4-amino-2-hydroxytoluene and 1-naphthol, as well as primary intermediates, such as 1-hydroxyethyl-4,5-diamino pyrazole sulphate, were employed. Results indicate that the extent of fading, as measured by the total colour change parameter, dE, is greatest for coloured hair subjected to both irradiation and shampooing, and significantly smaller for hair undergoing only irradiation or washing. Colour loss has been also found to be dependent upon the hair type employed, with coloured natural white and bleached hair undergoing much greater change than coloured brown hair. It has been also shown that hair colour based on pyrazole intermediates displayed the deepest fading as a result of shampooing (dE 4,6 after 10 shampooings) and irradiation per shampooing (dE 14,16 after 32 h of light exposure and four shampooings). The contribution of UV light (UVB + UVA) to the artificial hair-colour loss was found experimentally to be dependent upon the irradiation dose and varied from 63% at 16 h of irradiation time to 27% at 48 h of light exposure. The theoretical extent of photoprotection by a formulation was assessed by calculating the percentage of UV light it attenuates in the wavelength range from 290 to 400 nm. The results indicate that UVB photofilters, such as octyl methoxy cinnamate, absorb <25% of the total UV irradiation at concentrations as high as 30 mg (g hair),1. UVA absorbers were found to be more effective, with benzophenone-3 and benzophenone-4 absorbing about 40% of UV at the same concentration. Corresponding experimental data were in reasonable agreement with the theoretical predictions. The data are also presented for colour protection with treatments containing two photo-absorbers: benzophenone-3,ZnO; benzophenone-4,ZnO; octyl methoxy cinnamate,ZnO; and dimethylpabaimidopropyl laurdimonium tosylate-benzophenone-3. [source] Characteristics of skin aging in Korean men and womenINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2005J. H. Chung Introduction Korea is located between Japan and Mainland China. The people of these three countries have similar appearances and it is difficult to differentiate between them. Although the population of Asia is more than half of the total population of the Earth, the inherent characteristics of Asian skin have not been well investigated. Commercial markets for cosmetics and drugs for photoaged skin are rapidly expanding in many Asian countries. Therefore, many investigators in the field of dermatology and cosmetology have become interested in brown Asian skin. Clinical characteristics of skin aging and photoaging in Asians Skin aging can be divided into two basic processes: intrinsic aging and photoaging [1]. Intrinsic aging is characterized by smooth, dry, pale, and finely wrinkled skin, whereas photoaging, which indicates premature skin aging in chronically photodamaged skin, is characterized by severe wrinkling and irregular pigmentation. The pattern of wrinkling in Asians seems to differ from that in Caucasians. Asians have coarser, thicker and deep wrinkles, particularly in the forehead, perioral and Crow's foot areas. In contrast, Caucasians usually have relatively fine cheek and Crow's foot wrinkles. The reasons for these differences are not known and need further investigation. There are racial, ethnic and genetic differences, and differences of skin structure and function, between the brown skin of Asians and the white skin of Caucasians. As Asian skin is more pigmented, acute and chronic cutaneous responses to UV irradiation differ from those in white skin. Many people believe, based on clinical impressions, that the main process of photoaging in Asians involves pigmentary changes, rather than wrinkling. However, no study has been performed to confirm this belief. Risk factors for skin wrinkles and their relative risks in Korean skin [2] Various factors such as age, sun-exposure, and smoking are known to be important risk factors for wrinkles. However, the relative risks of each factor on wrinkles in the brown skin of Asians have not been investigated, and they could differ from those in Caucasians. An evaluation system for skin wrinkling is necessary for Asian skin [3]. Thus, we developed an eight-point photographic scale for assessing wrinkles in both Korean genders [2]. This scale can probably be applied to the populations of other Asian countries, at least to the Japanese and Chinese. The pattern of wrinkles in both genders appears to be similar. Age Age is an important risk factor for wrinkling in Asians, as in Caucasians. Korean subjects in their 60s showed a 12-fold increased risk of wrinkling, while subjects in their 70s have a 56-fold increased risk compared with young age group. UV light It is well known that the UV component in sunlight can cause and accelerate photoaging. The pigmented skin of Asian may better protect skin from acute and chronic UV damage. However, we found a strong association between sun-exposure and the development of wrinkling in Koreans. It was found that sun exposure of more than 5 h per day was associated with a 4.8-fold increased risk in wrinkling versus less than 2 h of sun-exposure in Koreans. Estrogen deficiency Korean females have more wrinkles than men, after controlling for age, sun exposure, and smoking, it was found that they have a 3.6-fold increased risk of developing wrinkles than their male counterparts [2]. It has also been reported, that the relative risk for wrinkling in women is higher than in men as for in white Caucasians [4]. The reason why women show more wrinkles remains to be determined. It is possible that a reduction in skin collagen because of estrogen deficiency in postmenopausal woman may aggravate wrinkling severity. Korean women with more than 10 years since menopause showed a 3.9-fold higher risk of wrinkling than the women 5 years of beyond menopause [5]. We demonstrated that women with a history of HRT have a significantly lower risk, more specifically, one fifth of the risk of facial wrinkling relative to those who had no history of HRT. Interestingly, we found that wrinkle severity significantly increased with an increasing number of full term pregnancies. The relative risk for severe wrinkling is increased by approximately 1.8-fold per full term pregnancy. Smoking It is known that smoking causes skin wrinkling in Caucasians, and that it plays no role in Blacks [6, 7]. Koreans with have a smoking history of more than 30 pack years showed a more than 2.8-fold increased risk of wrinkles [2]. The relative risks of wrinkles associated with a 30,50 pack-years history of smoking were 2.8- and 5.5-fold, respectively. Dyspigmentation in Asian skin To follow pigmentary changes, six photographic standards for both genders were developed for Korean skin, to produce a 6-point scale [2, 8]. Hyperpigmented spots, mostly lentigines, were prominent among women, while seborrheic keratosis tended to be more prominent in men. Seborrheic keratosis in Korean men Seborrheic keratoses (SKs) are benign cutaneous tumors. They have diverse clinical and histopathological appearances and are very common in the elderly (over 50 years old). The etiology of SKs is not well understood, although patients with a great number of lesionsshow a familial trait with an autosomal dominant pattern, and human papilloma virus has been suggested as possible cause because of verrucous appearance of the lesions. Exposure to sunlight has been suggested to be a risk factor for SKs. However, there is still some debate in terms of the role of sunlight. Recently, we have investigated the clinical characteristics of SKs and relationship between SKs and sunlight exposure in Korean males [9]. The prevalence of SKs in Koreans increases with age; it rose from 78.9% at 40 years, to 93.9% at 50 years and 98.7% in those over 60 years. Exposed areas, i.e. the face, neck and dorsum of the hands, demonstrate a significant increase in the prevalence of SKs by decade, whereas partly exposed areas, although SKs tended to increase in prevalence with age, this trend was not significant. When the estimated body surface area (BSA) is taken into account, the number of SKs on both the face and dorsum of the hands (0.51 ± 0.08 per 1% BSA) was over-represented compared with the trunk. SKs were also concentrated on the neck (0.38 ± 0.07 per 1% BSA) and in the V-area (0.47 ± 0.09 per 1% BSA). Outer forearms also showed 3-fold more SKs per unit area than neighboring arms and inner forearms, which are classified as partly exposed area (0.09 ± 0.02, 0.03 ± 0.01, respectively). The total area covered by SKs on exposed area also became significantly larger with aging than on intermittently exposed areas. These results indicate that exposure to sunlight might be related to SK growth. Our results indicated that excessive sun exposure is an independent risk factor of SKs. After controlling for age, smoking, and skin type, subjects with a sun exposure history of more than 6 hours per day showed a 2.28-fold increased risk of having severe SKs (n , 6) compared with those exposed for less that 3 h per day. These findings indicated that sun-exposure may play an important role in SK development. In summary, SKs are very common in Korean males and represent one of the major pigmentary problems. SKs concentrate on exposed skin, especially on the face and dorsum of the hands. Both age and lifetime cumulative sunlight exposure are important contributing factors and may work in a synergistic manner. Conclusion Many people tend to believe that wrinkles are not a prominent feature of Asian photoaged skin, and that dyspigmentation is a major manifestation in Asian skin. Contrary to this impression, wrinkling is also a major problem in the photoaged skin of Asians, and Korean people showing severe pigmentary changes usually tend to have severe wrinkles. In conclusion, the wrinkling patterns and pigmentary changes of photoaged skin in East Asians differ from those of Caucasians, and the relative risks of aggravating factors may be different from those of Caucasian skin. References 1.,Gilchrest, B.A. Skin aging and photoaging: an overview. J. Am. Acad. Dermatol. 21, 610,613 (1989). 2.,Chung, J.H. et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Arch. Dermatol. 137, 1043,1051 (2001). 3.,Griffiths, C.E. et al. A photonumeric scale for the assessment of cutaneous photodamage. Arch. Dermatol. 128, 347,351 (1992). 4.,Ernster, V.L. et al. Facial wrinkling in men and women, by smoking status. Am. J. Public Health. 85, 78,82 (1995). 5.,Youn, C.S. et al. Effect of pregnancy and menopause on facial wrinkling in women. Acta Derm. Venereol. 83, 419,424 (2003). 6.,Kadunce, D.P. et al. Cigarette smoking: risk factor for premature facial wrinkling. Ann. Intern. Med. 114, 840,844 (1991). 7.,Allen, H.B., Johnson, B.L. and Diamond, S.M. Smoker's wrinkles? JAMA. 225, 1067,1069 (1973). 8.,Chung, J.H. Photoaging in Asians. Photodermatol. Photoimmunol. Photomed. 19, 109,121 (2003). 9.,Kwon, O.S. et al. Seborrheic keratosis in the Korean males: causative role of sunlight. Photodermatol. Photoimmunol. Photomed. 19, 73,80 (2003). [source] Influence of environmental stress on skin tone, color and melanogenesis in Japanese skinINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2005K. Kikuchi Introduction It is needless to say that one of the most potent environmental stress for melanogenesis of the human skin is the effect of ultraviolet (UV) light from the sunlight. Characteristic skin aging as a result of this UV light is recognized as photoaging. Clinical features in photoaging are wrinkles, skin laxity, coarseness, leathery, yellowing, lentigenes, mottled pigmentation, telangiectasia, sebaceous hypertrophy and purpura. There is an apparent difference in clinical features in photoaging among different races, i.e. between Caucasians, African American and Asians that include Japanese. Not only photo skin type but also environmental factors, such as climate, latitude, altitude and their habit of sunbathing, smoking and skin care influence the characteristic development of their photoaging. Racial difference in photoaging Caucasians tend to develop skin laxity and fine wrinkles more than Asians [1]. Asians tend to produce coarser wrinkles than the Caucasians although their development is rather late in life. There is also a difference in the skin color. Pigmentation is an earliest and prominent skin changes in Asians [1] and it increases with age [2]. In contrast, pigmentation is not apparent in the Caucasians although redness probably because of an increase in cutaneous vascularization becomes prominent in middle aged Caucasians [2]. Chung reported that seborrheic keratosis is a major pigmentary lesion in men, whereas hyperpigmented macules are prominent features in women in Koreans [3]. Melanogenesis pigmentation disorders in Japanese Ephelides (freckles) are commonly found in those with photo skin type I who have fair skin and red eyes and blond hair. They are also found in the Japanese. Clinical feature reveals that multiple small pigmentary macules on sun-exposed areas mainly on the mid-portion of the face. These lesions seem to be familial, becoming apparent even in early childhood after sun exposure. Melasma is an acquired pigmentary disorder commonly found in middle aged Japanese women characterized by irregular brown macules and patches on the sun-exposed areas on the face typically as bilaterally present macules on the cheeks. An increase in sex hormones as a result of pregnancy and intake of contraceptive pills is one of the etiological factors to develop melasma. Sun exposure also worsens it. Nevus of Ota is also a common pigmentary disorder found in the Japanese. It is usually unilateral, blue-brown to slate-gray pigmentary macules on the eyelid and cheek that appear in early childhood or in puberty. Acquired dermal melanocytosis is also a pigmentary disorder, in which dermal melanocytes are found as shown in nevus of Ota, characterized by bilateral brown to blue-gray macules on the forehead, temple, eyelid and malar areas in middle aged Japanese women. This tends to be misdiagnosed as melasma. Solar lentigo is an acquired pigmented macule induced by sun exposure. Solar lentigines are usually multiple, circumscribed brown macules. There are two types of solar lentigo. One is a small macular type, characterized by multiple, small brown macules whose diameter is less than 5 mm, being similar to ephelides (freckles). The other type is a large macular type, characterized by a few round to oval, brown macules whose diameter is beyond 1 cm. Some of their surface are hyperkeratotic and become elevated to produce seborrheic keratosis. Again, the early sign of photoaging in Japanese is pigmentated spots and these pigmentation disorders increase with age. Among the pigmentary changes, nevus of Ota, acquired dermal melanocytosis, melasma and large macular type of solar lentigo are characteristic skin changes found in the Japanese in addition to ephelides and small macular type of solar lentigo. Seasonal changes of the various functional properties of the skin including skin color assessed by non-invasive bioengineering techniques [4]. When we consider skin tone, color and melanogenesis, UV light from the sunlight is the most potent environmental stress, although we cannot forget also the important influence of environmental relative humidity affects our skin functions as well as its appearance. We investigated seasonal influences on the various properties of the skin in 39 healthy Japanese females consisting of different age groups. Their skin is thought to be affected by the UV light in summer, and by the exposure to the dry and cold air in winter. Materials and methods Biophysical, non-invasive measurements, including transepidermal water loss (TEWL) as a parameter for the barrier function of the stratum corneum (SC), high frequency conductance as a parameter for the hydration state of the SC, skin color and casual surface lipid levels, were conducted during late summer and winter months. Skin color was determined with a chromameter according to the L*a*b* CIE 1976 system, where L* is an attribute on the luminance scale, a* that on the red versus green scale and b* that on the yellow versus blue scale. All the measurements were conducted in an environment controlled-chamber (21 ± 1 °C room temperature, and 50 ± 3% relative humidity). Results The barrier function of the SC was found to be significantly impaired in winter on the cheek as compared with that measured in summer, whereas no such seasonal change was apparent both in the hydration state of the SC and sebum levels on the cheek. In the assessment of the skin color on the cheek, a significant increase in a* (redness) and a decrease in b* (yellowness) were observed in winter. In contrast, on the flexor forearm, the values of L* (luminescence) increased in winter, but no seasonal change was noted in the values of a* and b*. In this study, skin changes with aging were also found by the non-invasive bioengineering methods. The value of TEWL on the cheek tended to increase with age, whereas no significant change was observed in the value of TEWL on the forearm. In the assessment of skin color, b* value on the cheek significantly increased with age whereas a* and L* values on the cheek did not show any significant change with age. Summary of this study We think that such an increase in yellowness with aging of the cheek skin is a phenomenon unique to the Japanese (Asians) since an increase in b* value was not observed in Caucasians [2]. The facial skin that is always exposed shows barrier impairment in a dry and cold winter environment and demonstrates increased yellowness in skin color because of a prolonged exposure to the UV light from the sun in the summer season. The non-invasive bioengineering methods are useful to demonstrate even invisible seasonal changes occurring in the same individuals and changes with age occurring in the skin. References 1.,Goh, S.H. The treatment of visible signs of senescence: the Asian experience. Br. J. Dermatol.122, 105,109 (1990). 2.,LeFur, I., Numagami, K., Guinot, C. et al. Age-related reference values of skin color in Caucasian and Japanese healthy women according to skin site. Pigment Cell Res. 7, 67 (1999). 3.,Chung, J.H., Lee, S.H., Youn, C.S. et al. Cutaneous photodamage in Koreans: influence of sex, sun exposure, smoking, and skin color. Arch. Dermatol. 137, 1043,1051 (2001). 4.,Kikuchi, K., Kobayashi, H., Le Fur, I. et al. Winter season affects more severely the facial skin than the forearm skin: comparative biophysical studies conducted in the same Japanese females in later summer and winter. Exog. Dermatol. 1, 32,38 (2002). [source] Relationship between UVA protection and skin response to UV light: proposal for labelling UVA protectionINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004M. Jean-Louis Refrégier Synopsis Definition and validation of a most relevant method to assess ultravoilet A (UVA) protection is a major concern for industry, authorities and consumers. However, due to the lack of knowledge about all the biological phenomena involved, the level of UVA protection needed, the ways to assess and label it, remain controversial. In order to overcome this situation, the paper deals with the outcomes of a mathematical model to calculate the distribution between ultravoilet B (UVB) and UVA components of skin responses to UV light. Mathematical calculations of UVB and UVA erythemal components of skin response to sunlight are developed from the well-known determination procedure to calculate the sunburn protection factor (SPF) of sunscreens. The model establishes the relationship between the UVA component of skin erythemal response to overall UV radiation received from sunlight and the ratio SPF/PFAe (erythemal protection factor) where SPF is the product and PFAe is related to the UVA part of the sunlight. Depending on the efficacy profile of sunscreens, the skin erythemal response may be mainly promoted by UVB rays as it normally occurs in unprotected skin or on contrary by UVA rays. Therefore, the efficacy profile of sunscreens defines the deepness where biological events induced by sunlight take place. This new relationship pinpoints the tremendous importance of the protection afforded by sunscreen products in the UVA range when erythema is taken as biological response. By extrapolation of the model to any other biological skin response it becomes possible to predict how to improve the efficiency of sunscreen products in the future. UVA protection afforded by sunscreens should be improved until reaching the same level as the SPF protection factor so that all UV-induced biological responses could be prevented or lowered at the same extend. To enforce this improvement, a proposal to classify sunscreen products in relation with their UVA protection is made. Résumé Bien que les méfaits du rayonnement UVA soient à présent reconnus et l'importance de s'en protéger au même titre que ceux du rayonnement UVB totalement admise, l'obtention d'un consensus au niveau international, sur les méthodes pour mesurer l'efficacité des produits solaires vis-à-vis des UVA et sur les niveaux d'efficacité souhaitables, semble impossible à atteindre. Afin de tenter de surmonter les obstacles actuels, nous présentons un modèle mathématique qui permet d'établir la relation qui dèfinit le poids relatif des rayonnements UVB et UVA dans l'initiation des phénomènes biologiques engendrés par le rayonnement solaire, en fonction des caractéristiques du produit solaire utilisé et en particulier de son efficacité protectrice vis-à-vis des UVA. Dans le cas de l'érythème nous établissons ainsi que la proportion des effets engendrés par le rayonnement UVA est définie par le rapport SPF/PFAe: le SPF étant le facteur de protection contre l'érythème vis-à-vis de l,ensemble du rayonnement UV, c'est l'indice de protection affiché sur les produits; et, PFAe étant le facteur de protection du produit vis-à-vis du seul rayonnement UVA. L'extrapolation possible de ce modèle à l'ensemble des phénomènes biologiques met en évidence que le facteur de proportionnalité entre la protection globale et celle apportée vis-à-vis des UVA (SPF/PFAe) permet d'établir une classification de la qualité des systèmes filtrants en fonction de leur aptitude à prèvenir l'ensemble des méfaits du rayonnement solaire. Ce modèle démontre l'importance d'évaluer l,efficacité protectrice des produits solaires vis-à-vis du rayonnement UVA et son enseignement plus pertinent que celle de seulement évaluer l'allure des spectres d'absorption. Nous jugeons que l'application directe de ce modèle, au même titre que les méthodes d'évaluation de l,allure des spectres d'absorption, n'est aujourd'hui pas souhaitable en raison des connaissances et donc de la validation insuffisantes des méthodes in vitro en particulier pour évaluer les produits non parfaitement photostables. En conséquence, nous proposons de mettre en place une qualification qui repose sur l'évaluation de la protection UVA par les mèthodes in vivo dûment étudiées et validées telles que les méthodes PPD ou PFA. La mise en place du système proposé de qualification des produits solaires, permettrait d'apporter rapidement aux consommateurs une meilleure information sur la qualité des produits et permettrait de créer une dynamique d'amélioration de la qualité de l'ensemble des produits commercialisés. [source] Dynamic Self-Assembly of the Liquid-Crystalline Smectic,A Phase,ADVANCED MATERIALS, Issue 17 2005K. Prasad A photoinduced transition in an azobenzene-containing liquid crystal leads to a phase that does not exist in the thermal cycle. The smectic,A phase is induced and stabilized only in the presence of UV light, producing fan-shaped focal conic textures typical of the SmA phase, as observed by polarized-light microscopy (see Figure). This dynamic self-assembly is explained by photoinduced nanophase segregation and a frustrated spin-gas model. [source] Pool boiling on a superhydrophilic surfaceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2003Y. Takata Abstract Titanium Dioxide, TiO2, is a photocatalyst with a unique characteristic. A surface coated with TiO2 exhibits an extremely high affinity for water when exposed to UV light and the contact angle decreases nearly to zero. Inversely, the contact angle increases when the surface is shielded from UV. This superhydrophilic nature gives a self-cleaning effect to the coated surface and has already been applied to some construction materials, car coatings and so on. We applied this property to the enhancement of boiling heat transfer. An experiment involving the pool boiling of pure water has been performed to make clear the effect of high wettability on heat transfer characteristics. The heat transfer surface is a vertical copper cylinder of 17 mm in diameter and the measurement has been done at saturated temperature and in a steady state. Both TiO2 -coated and non-coated surfaces were used for comparison. In the case of the TiO2 -coated surface, it is exposed to UV light for a few hours before experiment and it is found that the maximum heat flux (CHF) is about two times larger than that of the uncoated surface. The temperature at minimum heat flux (MHF) for the superhydrophilic surface is higher by 100 K than that for the normal one. The superhydrophilic surface can be an ideal heat transfer surface. Copyright © 2002 John Wiley & Sons, Ltd. [source] Photolithographic Patterning of Ring-Opening Metathesis Catalysts on Silicon,ADVANCED MATERIALS, Issue 1 2005F. Harris Ruthenium-based metathesis catalysts have been successfully covalently bound to a thermal oxide layer on a Si(100) wafer. Selective inactivation of the catalyst is achieved via exposure to UV light using standard photolithographic techniques. Subsequent exposure of the wafer to a suitable monomer results in the formation of a patterned polymeric film that is covalently attached to the oxide layer (see Figure). [source] Photoinitiating polymerization to prepare biocompatible chitosan hydrogelsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Xiaohong Hu Abstract Chitosan hydrogels were prepared from water soluble chitosan derivatives (chitosan-MA-LA, CML) by photoinitiating polymerization under the existence of Irgacure2959 and the irradiation of UV light. The CML was obtained by amidation of the amine groups of chitosan with lactic acid and methacrylic acid. Gelation time of the hydrogel could be adjusted within a range of 5,50 min, and controlled by factors such as the degree of MA substitution, initiator concentration, existence of oxygen, and salt. The dry hydrogel adsorbed tens to hundred times of water, forming a highly hydrated gel. The swelling ratio was smaller at the higher degree of MA substitution, higher pH, and higher salt concentration. Rheological test showed that the hydrogel is elastomeric in the measuring frequency range, with a storage modulus and loss modulus of 0.8,7 kPa and 10,100 Pa, respectively. In vitro culture of chondrocytes demonstrated that the cells could normally proliferate in the extractant of the hydrogels, showing no cytotoxicity at lower initiator concentration. By contrast, the extractant of the hydrogel made by the redox initiating system, i.e., ammonium persulfate (APS) and N,N,N,,N,-tetramethylethylenediamine (TEMED), showed apparent cytotoxicity. Thus, the chitosan hydrogels initiated by the Irgacure2959 have better comprehensive properties, in particular better biocompatibility, and are more suitable for biomedical applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] A positive-working photosensitive polyimide based on thermal cross-linking and acidolytic cleavageJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Myung-Sup Jung Abstract A novel positive-working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three-component PSPI was synthesized from 4,4,-oxydiphthalic anhydride and 2,2,-bis(3-amino-4-hydroxyphenyl)hexafluoropropane through ring-opening polymerization and subsequent thermal cyclization. 2,2,-bis(4-(2-(vinyloxy)ethoxy)phenyl)propane (BPA-DEVE) was used as a vinylether compound and diphenyliodonium 5-hydroxynaphthalene-1-sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA-DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA-DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 ,m in a 3.7-,m-thick film was obtained from the three-component PSPI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Stability of poly(N -propargylamide)s under ultraviolet irradiationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Jianping Deng Abstract This article investigates the photostability of poly(N -propargylamide)s under different conditions, on the basis of which application research for this class of highly functional polymers can be performed. With helical polymer 1 [monomer: CCCH2NHCOCH(C2H5)2] taken as a representative, some affecting factors, including the ultraviolet (UV)-light intensity, presence of oxygen, far-UV and near-UV light, and temperature, were investigated. It was found that increasing the UV-light intensity accelerated the degradation of polymer 1. When oxygen was present, it also facilitated the degradation. Far-UV light rather than near-UV light played a predominant role in initiating the degradation of polymer main chains. Elevating the temperature of the polymer solution during UV irradiation made the degradation accelerate. Storing the polymer under weak UV light, in the absence of oxygen, and at a low temperature was favorable for keeping the polymer stable. These findings are important not only from a scientific point of view but especially for developing practical applications of this type of polymer on the basis of its photodegradability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Photografting of unable-to-be-irradiated surfaces.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Abstract In this article, a batch liquid-phase process was reported, by which the photo-initiated grafting polymerization could be carried out on the dark surfaces that were not directly irradiated by UV light. In the reaction system, an aluminum foil was placed horizontally to reflect UV light back and form a dark area underneath where the grafting polymerization took place. The occurrence of the polymerization was demonstrated by gravitational analyses and XPS spectra. The factors affecting the grafting reaction have been studied and the results showed that increasing irradiation time, reaction temperature, and benzophenone concentration and decreasing distance (D) between the light area and the place where grafting reaction took place were beneficial to the grafting reaction. The highest grafting density was obtained at a acrylic acid concentration of 15 vol %. Moreover, some further investigations were also made. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 118,124, 2007 [source] Behavioural evidence for ultraviolet vision in a tetraonid species , foraging experiment with black grouse Tetrao tetrixJOURNAL OF AVIAN BIOLOGY, Issue 2 2002Heli Siitari In addition to wavelengths visible to humans (400,700 nm), many birds are able to detect near ultraviolet light (320,400 nm). Most studies of ultraviolet (UV) vision in birds have concentrated on the importance of UV vision in intraspecific signalling, especially in passerine birds. However, birds may also use UV vision for other purposes, e.g. foraging. We performed a laboratory experiment to test whether a tetraonid species, black grouse Tetrao tetrix, could detect the difference between UV-reflecting and non-UV-reflecting food items (two colour morphs of bilberry Vaccinium myrtillus). Black grouse preferred UV-reflecting berries when UV light was used for illumination, but showed no preference in the absence of UV light. This observation establishes a potential UV sensitivity in this species; such a sensitivity should be considered in behavioural experiments with this species. [source] Enhanced photodegradation of bisphenol A in the presence of ,-cyclodextrin under UV lightJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2006Guanghui Wang Abstract Enhancement of the photodegradation of bisphenol A (BPA) by ,-cyclodextrin (,-CD) was investigated under a 30 W UV disinfection lamp (,max = 254 nm). The photodegradation rate of BPA in aqueous solutions with ,-CD was faster than that in aqueous solutions without ,-CD; for example, after 50 min of UV irradiation, ,-CD had increased the photodegradation efficiency by about 46.5% for 10 mg dm,3 BPA. The photodegradation of 2.5,20 mg dm,3 BPA in aqueous solutions was found to follow pseudo-first-order kinetics. The first-order rate constant showed a 12-fold increase in the presence of ,-CD. Factors such as ,-CD concentration, pH, BPA initial concentration and organic solvent influencing the photodegradation of BPA were studied and are described in detail. Variations in the pH and electrical conductivity of solutions were observed during the photodegradation process. The enhancement of photodegradation of BPA results mainly from the lower bond energy between some atoms in the BPA molecule after inclusion interaction with ,-CD. Copyright © 2006 Society of Chemical Industry [source] Immune protective effect of a moisturizer with DNA repair ingredientsJOURNAL OF COSMETIC DERMATOLOGY, Issue 2 2008Cheré R Lucas MD Summary Ultraviolet (UV) light damages DNA and impairs immune surveillance. The faulty repair of DNA after UV exposure is associated with immune suppression and facilitates photodamage that leads to photoaged skin and the growth of skin cancer. Sunscreens have been developed to filter UV light from entering the skin, but are not beneficial once DNA damage has occurred. Enhancing DNA repair after UV radiation may provide added advantage and prevent UV immunosuppression. This study was performed to determine whether a product with DNA repair ingredients prevents UV-induced suppression of contact hypersensitivity responses in vivo. Solar simulated radiation was delivered on skin with and without topical treatment with a moisturizer containing DNA repair enzymes (Advanced Night Repair Concentrate). Subjects were then sensitized to the hapten dinitrochlorobenzene, and the level of resultant contact hypersensitivity response was elicited 2 weeks later. Contact hypersensitivity response measured by skin fold thickness was significantly suppressed in untreated UV-irradiated subjects but not in subjects treated with DNA repair moisturizer after solar simulated radiation. Our results indicate that DNA repair ingredients significantly prevent UV-induced immune suppression. [source] A bird's eye view of the peppered mothJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2000Majerus Industrial melanism in Biston betularia is one of the best known examples of the role of natural selection in evolution and has received considerable scrutiny for many years. The rise in frequency of the dark form of the moth (carbonaria) and a decrease in the pale form (typica) was the result of differential predation by birds, the melanic form being more cyptic than typica in industrial areas where the tree bark was darkened by air pollution. One important aspect of early work evaluating the relative crypsis of the forms of B. betularia on tree trunks with different lichen flora was the reliance on human observers. Humans, however, do not have the same visual capabilities as birds. Birds have well-developed ultraviolet (UV) vision, an important component of their colour processing system that affects many aspects of behaviour, including prey detection. We examined the UV characteristics of the two forms of B. betularia and a number of foliose and crustose lichens. In human visible light the speckled form typica appeared cyptic when seen against a background of foliose lichen, whereas the dark form carbonaria was conspicuous. Under UV light the situation was reversed. The foliose lichens absorbed UV and appeared dark as did carbonaria. Typica, however, reflected UV and was conspicuous. Against crustose lichens, typica was less visible than carbonaria in both visible and UV light. These findings are considered in relation to the distribution and recolonization of trees by lichens and the resting behaviour of B. betularia. [source] | |||||||||||||||||||||||||||||||||||||