Showing papers on "Ultraviolet light published in 2002"
TL;DR: At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap–selective protonation of the side walls of the tube, which is readily reversed by treatment with base or ultraviolet light.
Abstract: Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.
3,635 citations
TL;DR: It is shown that in lethally irradiated mice that had received BM transplants, LCs of host origin remained for at least 18 months, whereas DCs in other organs were almost completely replaced by donor cells within 2 months.
Abstract: Langerhans cells (LCs) are bone marrow (BM)–derived epidermal dendritic cells (DCs) that represent a critical immunologic barrier to the external environment, but little is known about their life cycle Here, we show that in lethally irradiated mice that had received BM transplants, LCs of host origin remained for at least 18 months, whereas DCs in other organs were almost completely replaced by donor cells within 2 months In parabiotic mice with separate organs, but a shared blood circulation, there was no mixing of LCs However, in skin exposed to ultraviolet light, LCs rapidly disappeared and were replaced by circulating LC precursors within 2 weeks The recruitment of new LCs was dependent on their expression of the CCR2 chemokine receptor and on the secretion of CCR2-binding chemokines by inflamed skin These data indicate that under steady-state conditions, LCs are maintained locally, but inflammatory changes in the skin result in their replacement by blood-borne LC progenitors
910 citations
TL;DR: It is shown that overexpression of Survivin in cells sensitive to p53-dependent cell death markedly inhibits apoptosis induced by ultraviolet light and should aid in the elucidation of the contribution of transcriptional repression to p 53-dependent apoptosis.
813 citations
TL;DR: The chitosan hydrogel due to its accelerating healing ability is considered to become an excellent dressing for wound occlusion and tissue adhesive in urgent hemostasis situations.
526 citations
TL;DR: Here it is demonstrated a process by which the transparent insulating oxide 12CaO·7Al2O3 (refs 7–13) can be converted into an electrical conductor and suggested that this concept can be applied to other main-group metal oxides, for the direct optical writing of conducting wires in insulating transparent media and the formation of a high-density optical memory.
Abstract: Materials that are good electrical conductors are not in general optically transparent, yet a combination of high conductivity and transparency is desirable for many emerging opto-electronic applications1,2,3,4,5,6. To this end, various transparent oxides composed of transition or post-transition metals (such as indium tin oxide) are rendered electrically conducting by ion doping1,2,3,4,5,6. But such an approach does not work for the abundant transparent oxides of the main-group metals. Here we demonstrate a process by which the transparent insulating oxide 12CaO·7Al2O3 (refs 7–13) can be converted into an electrical conductor. H- ions are incorporated into the subnanometre-sized cages of the oxide by a thermal treatment in a hydrogen atmosphere; subsequent irradiation of the material with ultraviolet light results in a conductive state that persists after irradiation ceases. The photo-activated material exhibits moderate electrical conductivity (∼0.3 S cm-1) at room temperature, with visible light absorption losses of only one per cent for 200-nm-thick films. We suggest that this concept can be applied to other main-group metal oxides, for the direct optical writing of conducting wires in insulating transparent media and the formation of a high-density optical memory.
413 citations
TL;DR: These results identify retroviral proteins that interact with a mammalian toll receptor and show that direct activation by such viruses may initiate in vivo infection pathways.
Abstract: Although most retroviruses require activated cells as their targets for infection, it is not known how this is achieved in vivo. A candidate protein for the activation of B cells by either mouse mammary tumor virus (MMTV) or murine leukemia virus is the toll-like receptor 4 (TLR4), a component of the innate immune system. MMTV caused B cell activation in C3H/HeN mice but not in C3H/HeJ or BALB/c (C.C3H Tlr4lps-d) congenic mice, both of which have a mutant TLR4 gene. This activation was independent of viral gene expression, because it occurred after treatment of MMTV with ultraviolet light or 2,2′-dithiodipyridine and in azidothymidine-treated mice. Nuclear extracts prepared from the lymphocytes of MMTV-injected C3H/HeN but not C3H/HeJ mice showed increased nuclear factor κB activity. Additionally, the MMTV- and Moloney murine leukemia virus envelope proteins coimmunoprecipitated with TLR4 when expressed in 293T cells. The MMTV receptor failed to coimmunoprecipitate with TLR4, suggesting that MMTV/TLR4 interaction is independent of virus attachment and fusion. These results identify retroviral proteins that interact with a mammalian toll receptor and show that direct activation by such viruses may initiate in vivo infection pathways.
411 citations
TL;DR: Emphasis is placed upon the signal transduction pathways in plant stress responses in which jasmonates act as a signal in the last decade, and examples are described on the role of jAsmonates in developmental processes.
Abstract: Plants are sessile organisms. Consequently they have to adapt constantly to fluctuations in the environment. Some of these changes involve essential factors such as nutrients, light, and water. Plants have evolved independent systems to sense nutrients such as phosphate and nitrogen. However, many of the environmental factors may reach levels which represent stress for the plant. The fluctuations can range between moderate and unfavorable, and the factors can be of biotic or abiotic origin. Among the biotic factors influencing plant life are pathogens and herbivores. In case of bacteria and fungi, symbiotic interactions such as nitrogen-fixating nodules and mycorrhiza, respectively, may be established. In case of insects, a tritrophic interaction of herbivores, carnivores, and plants may occur mutualistically or parasitically. Among the numerous abiotic factors are low temperature, frost, heat, high light conditions, ultraviolet light, darkness, oxidation stress, hypoxia, wind, touch, nutrient imbalance, salt stress, osmotic adjustment, water deficit, and desiccation. In the last decade jasmonates were recognized as being signals in plant responses to most of these biotic and abiotic factors. Signaling via jasmonates was found to occur intracellularly, intercellularly, and systemically as well as interorganismically. Jasmonates are a group of ubiquitously occurring plant growth regulators originally found as the major constituents in the etheric oil of jasmine, and were first suggested to play a role in senescence due to a strong senescence-promoting effect. Subsequently, numerous developmental processes were described in which jasmonates exhibited hormone-like properties. Recent knowledge is reviewed here on jasmonates and their precursors, the octadecanoids. After discussing occurrence and biosynthesis, emphasis is placed upon the signal transduction pathways in plant stress responses in which jasmonates act as a signal. Finally, examples are described on the role of jasmonates in developmental processes.
395 citations
TL;DR: Initial results from a study of the interaction of soft X-ray radiation, generated by a free-electron laser, with Xe atoms and clusters are presented, finding that, whereasXe atoms become only singly ionized by the absorption of single photons, absorption in clusters is strongly enhanced.
Abstract: Intense radiation from lasers has opened up many new areas of research in physics and chemistry, and has revolutionized optical technology. So far, most work in the field of nonlinear processes has been restricted to infrared, visible and ultraviolet light, although progress in the development of X-ray lasers has been made recently. With the advent of a free-electron laser in the soft-X-ray regime below 100 nm wavelength, a new light source is now available for experiments with intense, short-wavelength radiation that could be used to obtain deeper insights into the structure of matter. Other free-electron sources with even shorter wavelengths are planned for the future. Here we present initial results from a study of the interaction of soft X-ray radiation, generated by a free-electron laser, with Xe atoms and clusters. We find that, whereas Xe atoms become only singly ionized by the absorption of single photons, absorption in clusters is strongly enhanced. On average, each atom in large clusters absorbs up to 400 eV, corresponding to 30 photons. We suggest that the clusters are heated up and electrons are emitted after acquiring sufficient energy. The clusters finally disintegrate completely by Coulomb explosion.
380 citations
TL;DR: In this paper, a thiol monomer is shown to copolymerize with vinyl ether, allyl, acrylate, methacrylate and vinylbenzene monomers.
Abstract: A thiol monomer is shown to copolymerize with vinyl ether, allyl, acrylate, methacrylate, and vinylbenzene monomers. These thiol−ene polymerizations are photoinitiated without the use of photoinitiator molecules. It is seen that the polymerization proceeds more readily when initiatorless samples are irradiated with light centered around 254 nm as compared to 365 nm light. To demonstrate resistance to oxygen inhibition, thin polymer films of 3−15 μm are polymerized while exposed to ambient air. Without photoinitiator molecules present, light is attenuated only by the monomer and polymer. This feature leads to greater penetration of ultraviolet light and allows for the polymerization of extremely thick polymers. Thick cures of up to 25 in. are obtained using a thiol−vinyl ether system.
341 citations
TL;DR: In this article, the photochemistry of elemental mercury in simulated flue gases was examined using quartz flow reactors, and the implications of photochemical oxidation of mercury with respect to direct ultraviolet irradiation of flue gas for mercury control, analysis of gases for mercury content, and atmospheric reactions are discussed.
Abstract: Photochemical reactions of mercury with various constituents in flue gas produced by burning coal could be an attractive alternative to dry sorbent- or wet scrubber-based processes for mercury control. The sensitized oxidation of elemental mercury using 253.7-nm ultraviolet radiation has been extensively studied. The photochemistry of elemental mercury in simulated flue gases was examined using quartz flow reactors. Mercury-containing simulated flue gases at temperatures between 80 and 350 °F were irradiated with 253.7-nm ultraviolet light. Results are presented for the photochemical removal of elemental mercury from simulated flue gases, as well as from nitrogen mixtures that contain oxygen, water vapor, or nitrogen oxide. Optimization of the process parameters, including light intensity, is discussed. The implications of photochemical oxidation of mercury with respect to direct ultraviolet irradiation of flue gas for mercury control, analysis of gases for mercury content, and atmospheric reactions are d...
315 citations
TL;DR: In this article, a new scheme for attachment of functionalized organic molecules to polycrystalline diamond films was proposed, where ultraviolet light was used to cause a local reaction between a hydrogen-terminated diamond surface and organic molecules present as a thin overlayer liquid film.
Abstract: We report a new scheme for attachment of functionalized organic molecules to polycrystalline diamond films. In this scheme, ultraviolet light is used to cause a local reaction between a hydrogen-terminated diamond surface and organic molecules present as a thin overlayer liquid film. Comparison of functionalized alkenes and alkanes shows that alkenes attach more efficiently. By attaching organic molecules with suitable protecting groups and then deprotecting after attachment to the surface, it is possible to prepare diamond surfaces terminated with carboxylic acid groups or with primary amine groups. These functional groups may serve as an attractive starting point for further chemical modification of diamond surfaces.
TL;DR: In vivo detection of (1)O(2) and O(2)(-*) by fluorescence quenching of two dansyl-based ROS sensors, the singlet oxygen specific DanePy and HO-1889NH, which is reactive to both singinglet oxygen and superoxide radicals.
Abstract: ;In order to understand the physiological functions of reactive oxygen species (ROS) generated in leaves, their direct measurement in vivo is of special importance. Here we report experiments with two dansyl-based ROS sensors, the singlet oxygen specific DanePy and HO-1889NH, which is reactive to both singlet oxygen and superoxide radicals. Here we report in vivo detection of 1 O 2 and O 2 – by fluorescence quenching of two dansyl-based ROS sensors, the 1 O2 specific DanePy and HO-1889NH, which was reactive with both 1 O2 and O2 – . The ROS sensors were administered to spinach leaves through a pinhole, and then the leaves were exposed to either excess photosynthetically active radiation or UV (280–360 nm) radiation. Microlocalization of the sensors’ fluorescence and its ROS-induced quenching was followed with confocal laser scanning microscopy and with fluorescence imaging. These sensors were specifically localized in chloroplasts. Quenching analysis indicated that the leaves exposed to strong light produced 1 O 2 , but hardly any O 2 – . On the other hand, the dominant ROS in UV-irradiated leaves was O2 – , while 1 O2 was minor.
TL;DR: This study intended to develop a pretreatment for samples, so that inactivated viruses would not be detected by the RT-PCR procedure, and may be applicable to other types of viruses, to viruses inactivated in other ways and to other molecular methods of virus detection.
TL;DR: A dithienylethene (DTE)-porphyrin (P)-fullerene (C(60) triad molecule in which intramolecular photoinduced electron transfer is controlled by the photochromic DTE moiety may eventually be useful in the design of photonic or optoelectronic devices.
Abstract: A dithienylethene (DTE)−porphyrin (P)−fullerene (C60) triad molecule in which intramolecular photoinduced electron transfer is controlled by the photochromic DTE moiety has been prepared. Irradiation of the molecule with visible light gives the open form of the dithienylethene (DTEo). Excitation of the porphyrin gives DTEo-1P-C60, which undergoes photoinduced electron transfer with a time constant of 25 ps to generate DTEo-P•+-C60•-. Irradiation with ultraviolet light produces the closed form of the dithienylethene (DTEc). Excitation of DTEc-P-C60 yields DTEc-1P-C60, whose porphyrin first excited singlet state is quenched in 2.3 ps by singlet−singlet energy transfer to DTEc, generating 1DTEc-P-C60 and precluding significant photoinduced electron transfer. Such highly reversible photonically controlled intramolecular photoinduced electron transfer may eventually be useful in the design of photonic or optoelectronic devices.
Patent•
22 Aug 2002
TL;DR: In this paper, a system and method for treatment of skin disorders is presented, directed toward the treatment of acne and acne scarring by treating sebaceous oil glands and the surrounding tissue with an exogenous chromophore composition and then exposing the target tissue to visible, infrared, or ultraviolet light to inhibit the activity of the oil gland and eliminate acne bacteria.
Abstract: Disclosed is a system and method for treatment of skin disorders. More particularly, the disclosed invention is directed toward the treatment of acne and acne scarring by treating sebaceous oil glands and the surrounding tissue with an exogenous chromophore composition and then exposing the target tissue to visible, infrared, or ultraviolet light to inhibit the activity of the oil gland and eliminate acne bacteria. The treatment method of the present invention may be futher augmented by enhancing the penetration of the topical composition into the oil gland and surrounding tissue through the use of procedures including enzyme peeling, microderm abrasion, or ultrasound.
TL;DR: It is demonstrated that in contrast to cellular stresses previously examined, hydrogen peroxide exposure affects Cdc25C but not C DC25A levels, and that oxidative stress may induce cell cycle arrest in part through the degradation of CDC25C.
TL;DR: The pWW0 replicon and stable inheritance region was very similar to the mini-replicon from IncP-9 antibiotic resistance plasmid pM3, with their Rep proteins forming a novel group of initiation proteins.
Abstract: Summary
The TOL plasmid pWW0 (117 kb) is the best studied catabolic plasmid and the archetype of the IncP-9 plasmid incompatibility group from Pseudomonas. It carries the degradative (xyl) genes for toluenes and xylenes within catabolic transposons Tn4651 and Tn4653. Analysis of the complete pWW0 nucleotide sequence revealed 148 putative open reading frames. Of these, 77 showed similarity to published sequences in the available databases predicting functions for: plasmid replication, stable maintenance and transfer; phenotypic determinants; gene regulation and expression; and transposition. All identifiable transposition functions lay within the boundaries of the 70 kb transposon Tn4653, leaving a 46 kb sector containing all the IncP-9 core functions. The replicon and stable inheritance region was very similar to the mini-replicon from IncP-9 antibiotic resistance plasmid pM3, with their Rep proteins forming a novel group of initiation proteins. pWW0 transfer functions exist as two blocks encoding putative DNA processing and mating pair formation genes, with organizational and sequence similarity to IncW plasmids. In addition to the known Tn4651 and IS1246 elements, two additional transposable elements were identified as well as several putative transposition functions, which are probably genetic remnants from previous transposition events. Genes likely to be responsible for known resistance to ultraviolet light and free radicals were identified. Other putative phenotypic functions identified included resistance to mercury and other metal ions, as well as to quaternary ammonium compounds. The complexity and size of pWW0 is largely the result of the mosaic organization of the transposable elements that it carries, rather than the backbone functions of IncP-9 plasmids.
Patent•
12 Mar 2002
TL;DR: In this paper, an interior illuminating apparatus for a vehicle includes an interior rear-view minor which is connected and fixed to an interior ceiling of the vehicle for observing the rear, and an operating unit adapted to receive the ultraviolet light from the LED is provided in the center part of the instrument panel.
Abstract: An interior illuminating apparatus for a vehicle includes an interior rear-view minor which is connected and fixed to an interior ceiling of the vehicle for observing the rear. An LED is provided in a vicinity of the interior rear-view mirror at a forward position in a traveling direction of the vehicle and radiates ultraviolet light on a center part of an instrument panel. An operating unit adapted to receive the ultraviolet light from the LED is provided in the center part of the instrument panel. The apparatus includes a starting switch for actuating the LED on and off. The operating unit has fluorescent layers coated thereon and containing a substance which emits fluorescence when irradiated with the ultraviolet light from the LED.
TL;DR: In this article, the effects of harvesting and two processing systems (two-phase and three-phase centrifugation) on olive oil quality were studied and it was determined that neither extraction method affects the presence of α-tocopherol and β-carotene, however, the phenolic content is higher in the two-phase method due to the addition of lukewarm water that is used to dilute the olive paste.
TL;DR: It is suggested that repeated UV irradiation can circumvent an immunologic mechanism that might otherwise destroy nascent UV-induced primary tumors that are strongly antigenic.
Abstract: Chronic irradiation of mice with ultraviolet (UV) light produces a systemic alteration of an immunologic nature. This alteration is detectable in mice long before primary skin cancers induced by UV light begin to appear. The alteration results in the failure of UV-irradiated mice to reject highly antigenic, transplanted UV-induced tumors that are rejected by unirradiated syngeneic recipients. The immunologic aspect of this systemic alteration was demonstrated by transferring lymphoid cells from UV-irradiated mice to lethally x-irradiated recipients. These recipients were unable to resist a later challenge with a syngeneic UV-induced tumor, whereas those given lymphoid cells from normal donors were resistant to tumor growth. Parabiosis of normal mice with UV-irradiated mice, followed by tumor challenge of both parabionts with a UV-induced tumor, resulted in the growth of the challenge tumors in both WV-irradiated and unirradiated mice. Splenic lymphocytes from tumor-implanted UV-treated mice were not cytotoxic in vitro against UV-induced tumors, whereas under identical conditions cells from tumor-implanted, unirradiated mice were highly cytotoxic. Our findings suggest that repeated UV irradiation can circumvent an immunologic mechanism that might otherwise destroy nascent UV-induced primary tumors that are strongly antigenic.
TL;DR: Platelet adhesion assay showed that PLA surface modified by chitosan/heparin complex could inhibit platelets adhesion and activation, and cell culture assay indicated thatPLA surface with CS/Hp complex showed enhanced cell adhesion.
Book•
26 Apr 2002
TL;DR: In this paper, the authors present guidelines for the choice of lamp technology for UV-based disinfection units for drinking water treatment and provide a questionnaire for the selection of the best lamp technology.
Abstract: Introduction Historical: Use of UV Light in Drinking Water Treatment Present State of Standards and Regulations Definition of Ultraviolet Light: Range and Natural Sources Solar Radiant Energy Available Lamp (or Burner) Technologies General Mercury Emission Lamps Currently Available Commercial Lamp Technologies Available Lamp Technologies Special Lamp Technologies Preliminary Guidelines for Choice of Lamp Technology UV Emission Yields and Mode of Control Zonal Distribution of Emitted Light Use of Ultraviolet Light for Disinfection of Drinking Water Introduction Germicidal Action Dose-Efficiency Concept Representative Test Organisms Competitive Effects in Disinfection with UV-Light Multihit, Multisite, and Step-by-Step Killing Concepts Design Factors for Reactor Geometry Mixing Conditions in UV-Water Treatment Operational Control of Efficiency Tentative Design Questionnaire for UV-Based Disinfection Units for Drinking Water Examples Use of UV in Photochemical Synergistic Oxidation Processes in Water Sanitation Basic Principles Combinations of Hydrogen Peroxide and UV-Light Synergism of Ozone and UV in Water Sanitation UV-Catalytic Processes Tentative Design Rules for UV-Synergistic Oxidation Processes Use of UV Light for Sanitation of Wastewater Regulations and Guidelines for Disinfection of Treated Wastewater General Characteristics of Effluents in Relation to Disinfection by UV-Light Aftergrowth and Photorepair after Exposure to UV Disinfection of Wastewater Applied UV Doses in Wastewater Disinfection Choice of Lamp Technology in Wastewater Disinfection Toxicity and Formation of By-Products Preliminary Conclusions on Wastewater Disinfection with UV Example General Conclusions Glossary References Index
Journal Article•
TL;DR: Vitamin D may have an important role in determining the effects of calcium on colorectal epithelial proliferation and may explain some of the discrepancies found previously in studies that examine the direct role ofcium on the coloreCTal epithelium.
Abstract: Epidemiological evidence suggests a potential role for vitamin D in colon cancer prevention. Vitamin D, absorbed from the intestine or derived from solar ultraviolet light, is metabolized in the liver to 25-hydroxyvitamin D (25-OH D(3)). Previous studies examining effects of vitamin D upon carcinogenesis have focused upon the active metabolite 1,25-dihydroxyvitamin D [1,25-(OH)(2) D(3)], which interacts with nuclear vitamin D receptors in several organs. Until recently, the metabolism of 25-OH D(3) to 1,25-(OH)(2) D(3) was believed to occur only in the kidney, but more recent studies have shown that 25-OH D(3) conversion to 1,25-(OH)(2) D(3) can occur in other tissues. We examined the association between fasting levels of 25-OH D(3), 1,25-(OH)(2) D(3), and BsmI polymorphism of the vitamin D receptor (VDR) gene with indices of colonic epithelial cell proliferation and differentiation in a chemoprevention study, after giving vitamin D or calcium and taking rectal biopsies that were incubated with bromodeoxyuridine. Vitamin D receptor polymorphism was determined by genotyping of the 3' BsmI polymorphism in intron eight of the VDR gene. No significant changes in cell proliferation or in differentiation were found in subjects between study start and end. However, fasting serum levels of 25-OH D(3) showed a highly significant decrease with whole crypt labeling index and the size of the proliferative compartment (phi h). There was no correlation between serum levels of 1,25-(OH)(2) D(3) and the proliferative parameters. Calcium supplementation induced a significant effect upon the relationship between serum 25-OH D(3) and rectal epithelial cell labeling index and phi h when studied by covariance analysis without a relationship with 1,25-(OH)(2) D(3) levels. VDR genotype did not influence the effects of serum 25-OH D(3) or serum 1,25-(OH)(2) D(3) levels upon proliferation. These data suggest that there might be a local effect of 25-OH D(3) on colonic epithelial cells through conversion of 25-OH D(3) to 1,25-(OH)(2) D(3). Subsequent studies have demonstrated the presence of 1alpha-hydroxylase mRNA in normal colorectal epithelium and in colorectal cancer. Thus, vitamin D may have an important role in determining the effects of calcium on colorectal epithelial proliferation and may explain some of the discrepancies found previously in studies that examine the direct role of calcium on the colorectal epithelium.
TL;DR: In this paper, negative photoresists (SU-8 and photosensitive polyimide) were fabricated by the pyrolysis of a closed quartz tube furnace in a forming gas (95% N 2, 5% H 2 ).
Abstract: Carbon structures were fabricated by the pyrolysis of photopatterned negative photoresists (SU-8 and photosensitive polyimide) on silicon and fused silica wafers. Results here are compared with those of positive resists published earlier by this group. Negative resist films need exposure to ultraviolet light prior to pyrolysis to produce carbon films. The pyrolysis was carried out in a closed quartz tube furnace in a forming gas (95% N 2 , 5% H 2 ) atmosphere. The pyrolysis process was characterized using a combination of thermogravimetric analysis and differential thermal analysis. The pyrolysis of SU-8 involved gas evolution in a narower range of temperature than polyimide, The adhesion of the carbon film was found to depend on the resist, the substrate, and the heating cycle used. The carbon structures were characterized in terms of their shrinkage during the pyrolysis, the resistivity, the degree of crystallinity and the peak separation in cyclic voltammetry. Carbons derived from pyrolysis of negative resists showed higher resistivity, vertical shrinkage, and peak-to-peak separation voltage than positive resists. Transmission electron microscope results showed a distinct lack of crystallinity even after pyrolysis at 1100°C, unlike the positive resist derived carbon.
Patent•
11 Jan 2002TL;DR: In this article, the attenuation factor is determined as a function of the integrated value of the quantity of incident light, and the output of an excimer laser source is controlled according to this attenuation factors to control the exposure thereby preventing lowering of exposure control precision.
Abstract: The quantity of ultraviolet light (IL) incident on a projection optical system (PL) is measured by means of an integrator sensor ( 9 ), and the quantity of ultraviolet pulse light (IL) that has passed through the projection optical system (PL) is measured by means of an irradiation monitor ( 32 ). The quantity of transmitted light is divided by the quantity of incident light to calculate the proportion at which the ultraviolet pulse light (IL) is attenuated in the projection optical system (PL), or an attenuation factor. The attenuation factor is determined as a function of the integrated value of the quantity of incident light. During exposure, the integrated value as quantity measured by means of the integrator sensor ( 9 ) is substituted into the function to estimate the transmissivity (attenuation factor) of the projection optical system (PL). The output of an excimer laser source ( 1 ) is controlled according to this attenuation factor to control the exposure thereby preventing lowering of exposure control precision due to illumination variations (or pulse energy variations) on the substrate caused by attenuation variations (transmissivity variations) in the projection optical system.
TL;DR: In this paper, it was shown that doping of indium-tantalum-oxide with nickel yields a series of photocatalysts, In(1-x)Ni(x)TaO(4) (x = 0-0.2), which induces direct splitting of water into stoichiometric amounts of oxygen and hydrogen under visible light irradiation with a quantum yield of about 0.66%.
Abstract: The photocatalytic splitting of water into hydrogen and oxygen using solar energy is a potentially clean and renewable source for hydrogen fuel. The first photocatalysts suitable for water splitting, or for activating hydrogen production from carbohydrate compounds made by plants from water and carbon dioxide, were developed several decades ago. But these catalysts operate with ultraviolet light, which accounts for only 4% of the incoming solar energy and thus renders the overall process impractical. For this reason, considerable efforts have been invested in developing photocatalysts capable of using the less energetic but more abundant visible light, which accounts for about 43% of the incoming solar energy. However, systems that are sufficiently stable and efficient for practical use have not yet been realized. Here we show that doping of indium-tantalum-oxide with nickel yields a series of photocatalysts, In(1-x)Ni(x)TaO(4) (x = 0-0.2), which induces direct splitting of water into stoichiometric amounts of oxygen and hydrogen under visible light irradiation with a quantum yield of about 0.66%. Our findings suggest that the use of solar energy for photocatalytic water splitting might provide a viable source for 'clean' hydrogen fuel, once the catalytic efficiency of the semiconductor system has been improved by increasing its surface area and suitable modifications of the surface sites.
TL;DR: Advance oxidation methods which utilise ultraviolet light and a photo absorber have been developed and patented, in which both iron salts and sulphite can be used as the photoabsorber.
TL;DR: In this paper, the authors demonstrate the unique potential and the versatility of the PEEM approach, and review the current status with a certain emphasis on experiments with soft x-ray excitation.
Abstract: The imaging of surfaces by means of photoexcitation electron emission microscopy (PEEM) has recently received considerable interest. This is mainly due to the extended use and availability of brilliant synchrotron radiation in the soft x-ray regime which generally facilitates studies with surface specificity and chemical selectivity. The most popular application of the x-ray PEEM (XPEEM) technique concerns studies of magnetic systems and phenomena. By exploiting the high degree of circular or linear polarization of the synchrotron light, the magnetic microstructure in both ferromagnets and antiferromagnets can be visualized. In this contribution we demonstrate the unique potential and the versatility of the PEEM approach, and review the current status with a certain emphasis on experiments with soft x-ray excitation. In some cases, the high-energy excitation studies can be complemented by laboratory experiments employing threshold photoemission with ultraviolet light (UV-PEEM). Current limitations and future developments and perspectives of the PEEM technique applied to magnetic systems are discussed.
Patent•
22 Mar 2002TL;DR: In this article, a portable data collection device is provided for reading fluorescent indicia, such as barcodes, which includes an adjustable aperture, a color detector array for imaging light received through the aperture, and a removable flash module to provide ultraviolet light.
Abstract: A portable data collection device is provided for reading fluorescent indicia, such as barcodes. The device includes a housing with a pivotable image capture module. The image capture module includes an adjustable aperture, a color detector array for imaging light received through the aperture, and a removable flash module to provide ultraviolet light. Optics in the image capture module focus the light received through the aperture onto the detector array, in which the detector array is movable with respect to the lens to provide proper focus of an image onto the detector array. The adjustable aperture has an iris wheel to control the amount of light received by the detector array. A programmed controller is provided in the housing which operates responsive to a user interface to image and decode indicia, or capture color digital images in memory. A display on the housing shows images received by the detector array in a non-fluorescent imaging mode to target indicia to be imaged and decoded, where the controller automatically adjusts the focus of the image by adjusting the focal distance between the detector array and the lens. In response to user actuation via the user interface, the controller energizes the flash module to emit light, including the excitation wavelength(s), which enable the indicia to fluoresce, and the detector array receives fluorescent light to capture an image frame of the indicia. The duration of the flash is in accordance with the amount of light measured by a light sensor in the image capture module. The indicia in the image frame is then decoded by the controller to provide data representative of the indicia.
TL;DR: Signs of photoaging including telangiectasias and mottled pigmentation of the face, neck, and chest, can be improved by IPL with a long-lasting result, and skin textural smoothing, although not easily quantified, is an additional benefit observed long-term.
Abstract: BACKGROUND. Photorejuvenation involves the use of lasers or light sources to reverse signs of photoaging. Multiple devices have been shown to be effective over the short-term. OBJECTIVE. To investigate the long-term clinical results on the face, neck and chest at 4 years using filtered flashlamp intense pulsed light (IPL) for treatment of photoaging changes of telangiectasias, dyspigmentation, and rough skin texture. METHODS. A chart review of 80 randomly selected patients with skin types I-IV who were treated by IPL during 1996 and 1997 was performed. Photos and patient self-assessment were graded for features of textural smoothness, telangiectasia severity, and blotchy pigmentation into four categories of worse, no change, slightly better (less than 50% improvement) and much better (greater than 50% improvement). RESULTS. At 4 years following initial treatment, skin textural improvement was noted in 83% of the subjects. Telangiectasias were improved in 82% of subjects, while pigmentation remained improved in 79%. The median number of treatments was 3. The face responded slightly better than the chest or neck. Most common side-effects included temporary mild crusting (19%), erythema (15%) and purpura (6%). CONCLUSION. Signs of photoaging including telangiectasias and mottled pigmentation of the face, neck, and chest, can be improved by IPL with a long-lasting result. Minimal or no downtime with minimal adverse effects can be achieved with the settings reported. Skin textural smoothing, although not easily quantified, is an additional benefit observed long-term. THIS STUDY WAS PRESENTED IN PART AT THE 2000 ASDS ANNUAL MEETING IN DENVER. THE AUTHORS ARE CONSULTANTS AND PRECEPTORS FOR LUMENIS. THE DEVICES USED IN THIS STUDY WERE PURCHASED AT A DISCOUNT. NO DIRECT FUNDING WAS PROVIDED FOR THIS STUDY. THE APPEARANCE of aging skin due to chronic exposure to ultraviolet light can be distinguished from chronologically or intrinsically aging skin. l Photoaging, resulting from chronic exposure to UV light, includes wrinkling of the skin, rough texture, dyspigmentation, and loss of elasticity. 2,3 These findings are explained by histologic evidence of epidermal thinning but more importantly, dermal changes of disorganized collagen bundles and clumping of elastic fibers. Changes within the matrix of the dermis and at the dermal-epidermal junction include reductions in procollagens I and III, collagen VII, and the fibrillin-rich microfibrillar apparatus at the dermo-epidermal junction.4 Photoaged skin displays prominent alterations in the cellular component and the extracellular matrix of the connective tissue with an accumulation of disorganized elastin and a severe loss of interstitial collagens.5 Similar changes may also affect superficial capillaries which can become skin surface telangiectasias. A variety of treatments to reverse this photodamage aging process have been employed. On one side of the