Visible Light

a b s t r a c t H.M. the King of Thailand proposed Bueng Makkasan, the repair factory belonging to the Royal Railway of Thailand (RTT), as a wastewater-collection pond of Bangkok City. It covers about 40 acres, with 5-m depth. The RRT wastewater pond functions at a repair factory and is the collection site of the directpolluted waste of homeless people living around the pond rim and also for temporary reservoir of two influent canals. The water hyacinth aquatic plants were grown well and covered almost the entire surface area of the pond.

We live with solar radiation from birth to death and have since the emergence of life on earth. Why then does skin cancer diagnosis remain so disturbingly high in Australia? Part of the problem is the majority of the population are of Northern European ancestry. Moving closer to the equator on mass we have carried with us a polymorphic melanocortin receptor gene on our melanocytes responsible for an incomplete tanning response. We attempt to protect ourselves with clothing and creams or remain indoors but this does not seem to be stemming the tide. Occupation, recreation or both drive us outside and into the sun. We need to be more successful at negotiating the potentially harmful effects by relooking at solar radiation and instead of focusing on the most harmful wavelengths look at the overall effect of the whole spectrum. We also need to reexamine our behaviour and exposure patterns. Prolonged periods indoors under artificial light punctuated with short bursts of intense irradiation is maladaptive. Creams aim to block the ultraviolet component, ignoring 90% of solar photons, the protective effect is incomplete, yet their use encourages more prolonged exposure. Protective behaviours are necessary for the most sensitive skin types but they are still at risk. For the rest of the population evolutionarily developed natural protective mechanisms can be employed. Regular moderate sun exposure, below the burn threshold, ideally aimed at early morning or late afternoon. Augmented with clothing, hats and creams with an appreciation of the incomplete protective effect of these measures.

Thin films of the lanthanum titanium oxynitride perovskite (LaTiO x N y ) synthesized by reactive radio-frequency sputtering on conductive Nb-doped strontium titanate (Nb:SrTiO 3 ) substrates are evaluated as photoelectrodes for water splitting reaction under visible light. The films are characterized by X-ray diffraction analysis, energy-dispersive spectroscopy, scanning electron and atomic force microscopy, and ultraviolet-visible spectroscopy. Thin films with polycrystalline, oriented, or epitaxial structures are obtained depending on the substrate temperature and plasma composition. The band-gap energies of the films thus prepared are in the range 2.05-2.35 eV. Photoelectrochemical measurements reveal that the photoactivity of these films increases with the quality of film crystallization. The flat-band position of LaTiO x N y is found to change with pH of the reactant solution. Surface modification with colloidal IrO 2 is also demonstrated to result in a marked increase in photoactivity, with the modified epitaxial LaTiO x N y film exhibiting a photocurrent density of ca. 70 µA cm -2 at +1.0 V vs. Ag/AgCl at pH 4.5 in aqueous Na 2 SO 4 solution under irradiation at visible wavelengths (λ > 420 nm).

A simple and sensitive technique, which utilizes the sensing of both the discharge current and the visible light emission from the discharge, has been developed to detect the arc formation during the operation of a high repetition rate TEA CO 2 laser. It is shown that the optical detection in the visible spectral region is more sensitive than that it is in the UV region and hence can be used more effectively to monitor the onset of arc formation, while the current signal is useful in the strong arc formation regime. We demonstrate that the trigger signals generated by both the methods can be employed for reliable protection of the laser system from catastrophic damage due to deleterious arc formation.

Hafnium indium zinc oxide thin-film transistors (TFTs) with a double-gate structure were evaluated for the first time. Compared with devices with a single bottom gate, TFTs with an additional top gate exhibit improved subthreshold swing, threshold voltage, and field-effect mobility, as well as smaller subthreshold currents upon exposure to visible light. This phenomenon is attributed to the more effective suppression of excess photocurrents by the application of a double-gate structure.

Traditionally, the toxic effects of petroleum have been investigated by conducting studies in the absence of ultraviolet radiation (UV). Photomediated toxicity is often not considered, and the toxic effects of an oil spill can be grossly underestimated. The toxicity of a weathered oil collected from a monitoring well at an abandoned oil field to Ceriodaphnia dubta was examined in the presence of UV. A solar simulator equipped with UVB, UVA, and cool white lamps was used to generate environmentally comparable solar radiation intensities. C. dubia were exposed to six concentrations of water accommodated fractions (WAF) of weathered oil in conjunction with three levels of laboratory simulated UV (Reference = < 0.002 ~tW/cm2 UVB; 3.0 gW/cm 2 UVA; Low = 0.30 ~tW/cm 2 UVB; 75.0 laW/cm 2 UVA; High = 2.0 ~tW/cm 2 UVB; 340.0 p.W/cm 2 UVA) and visible light. Seven day static renewal bioassays were used to characterize WAF/UV toxicity. WAF toxicity significantly (p < 0.05) increased when the organisms were exposed to WAF in the presence of UV. The photoenhanced toxicity of the WAF increased with WAF concentration within each UV regime. Relative to the reference light regime, the average number of neonates from adults exposed to 1.6 mg TPH/L decreased significantly by 20% within the low light regime, and by 60% within the high light regime. These results indicate that organisms exposed to dissolved-phase weathered oil in the presence of environmentally realistic solar radiation, exhibit 1.3-2.5 times greater sensitivity, relative to organisms exposed under traditional laboratory fluorescent lighting.

Recent advancements in laser and visible light sensor technology allows for the collection of photorealistic 3D scans of large scale spaces. This enables the technology to be used in real world applications such as crime scene investigation. The 3D models of the environment obtained with a 3D scanner capture visible surfaces but do not provide semantic information about salient features within the captured scene. Later processing must convert these raw scans into salient scene structure. This paper describes ongoing research into the generation of semantic data from the 3D scan of a crime scene to aid forensic specialists in crime scene investigation and analysis.

Specimens of three different denture base resins were repaired with visible light cured (VLC) reline material and with the traditional sprinkle on autopolymerizing PMMA repair resin. Flexural properties were measured before and after repair and compared. These tests revealed that fiber reinforced polymethylmethacrylate, (PMMA) denture base joints repaired with autopolymerizing acrylic resin can produce superior bonding properties. Transverse strength of joints made and repaired with the VLC acrylic resin system gave favorable pre-repair strength and lower post-repair strength. Significant differences were found between the flexural properties of the denture base resins used before and after repair. Plain and fiber reinforced PMMA acrylic resin joints repaired with the VLC reline material, showed a reduction of transverse strength ranging from 48.2%-56.4% of the original values. However, only 26.1% loss of strength was found for VLC denture base resin joints repaired with VLC reline ...

Less than 20 of the hundreds of carotenoids found in nature are found in the human body. These carotenoids are present in the body from the foods or dietary supplements that humans consume. The body does not synthesize them. Among the carotenoids present in the body, only lutein and its coexistent isomer, zeaxanthin, are found in that portion of the eye where light is focused by the lens, namely, the macula lutea. Numerous studies have shown that lutein and zeaxanthin may provide significant protection against the potential damage caused by light striking this portion of the retina. In the eye, lutein and zeaxanthin have been shown to filter high-energy wavelengths of visible light and act as antioxidants to protect against the formation of reactive oxygen species and subsequent free radicals. Human studies have demonstrated that lutein and zeaxanthin are present in the skin, and animal studies have provided evidence of significant efficacy against light-induced skin damage, especially the ultraviolet wavelengths. Little was known about the protective effects of these carotenoids in human skin until recently. This article reviews the scientific literature pertaining to the effects that lutein and zeaxanthin exhibit in the human eye and skin.

Hydrogen evolution was observed from the noble-metal-free catalyst systems, comprising Rose Bengal, BF xbridged cobaloximes, and triethylamine, in an aqueous solution under irradiation of visible light. Two types of BF x -bridged cobaloximessnamely, the annulated cobaloximes [Co(dmgBF 2 ) 2 (H 2 O) 2 ] (1, dmgBF 2 ) (difluoroboryl)dimethylglyoximate anion) and [Co(dpgBF 2 ) 2 (H 2 O) 2 ] (2, dpgBF 2 ) (difluoroboryl)diphenylglyoximate anion), and the clathrochelated cobaloximes [Co(dmg(BF) 2/3 ) 3 ](BF 4 ) (3) and [Co(dpg(BF) 2/3 ) 3 ](BF 4 ) (4)swere used as catalysts. Among the four cobalt complexes, complex 1 displayed the highest hydrogenevolving efficiency, with turnovers up to 327. Complexes 2 and 4 that bear the diphenylglyoximate ligands exhibited much lower efficiencies as compared with their analogues 1 and 3 that have the dimethylglyoximate ligands. The hydrogen-evolving efficiency of the annulated cobalt(II) complex 1 that contains two labile axial ligands is more than three times as high as that of the encapsulated cobalt(III) complex 3 that has a single macrobicyclic ligand. The different pathways for formation of the cobalt(I) species from these two types of cobaloximes are discussed on the basis of the results obtained from fluorescence and laser flash photolysis spectroscopic studies.

In this work, we describe a kinetically controlled crystallization process assisted by an oriented attachment (OA) mechanism based on a nonaqueous sol-gel synthetic method (specifically, the reaction of titanium(IV) chloride (TiCl 4 ) with n-octanol) to prepare re-crystallized anatase TiO 2 mesocrystals (single crystal). The kinetics study revealed a multi-step and hierarchical process controlled by OA, and a high resolution transmission electron microscopy (HRTEM) analysis clearly shows that the synthesized mesocrystal presents a truncated bipyramidal Wulff shape, indicating that its surface is dominated by {101} facets. This shape is developed during the recrystallization step. The material developed here displayed superior photocatalytic activity under visible light irradiation compared to TiO 2 -P25 as a benchmarking.

Iris recognition imaging constraints are receiving increasing attention. There are several proposals to develop systems that operate in the visible wavelength and in less constrained environments. These imaging conditions engender acquired noisy artifacts that lead to severely degraded images, making iris segmentation a major issue. Having observed that existing iris segmentation methods tend to fail in these challenging conditions, we present a segmentation method that can handle degraded images acquired in less constrained conditions. We offer the following contributions: 1) to consider the sclera the most easily distinguishable part of the eye in degraded images, 2) to propose a new type of feature that measures the proportion of sclera in each direction and is fundamental in segmenting the iris, and 3) to run the entire procedure in deterministically linear time in respect to the size of the image, making the procedure suitable for real-time applications.

1] Absorption by light-absorbing carbon (LAC) particles increases when the carbon is mixed with other material, and this change affects climate forcing. We investigate this increase theoretically over a realistic range of particle sizes. Perfect mixing at the molecular level often overestimates absorption. Assuming that LAC is coated by a concentric shell of weakly absorbing material, we calculate absorption by a range of realistic particle sizes and identify regimes in which absorption behaves similarly. We provide fits to amplification in five regions: (1) small cores and intermediate cores, both with large shells; (3) small to intermediate cores with intermediate shells; (4) cores with growing shells; and intermediate to large cores with large shells. Amplification in region 1 is highest but is physically implausible. Amplification in region 5 is constant at about 1.9 and represents an asymptote for particles with broad size distributions. Because absorption by aggregates is amplified by about 1.3 above spherical particles, and that factor is lost when particles are coated, we suggest that absorption by aged aerosol is about 1.5 times greater than that of fresh aerosol. The rate at which particles acquire sufficient coating to increase their original diameter by 60% is important in determining total absorption during their atmospheric lifetimes. Fitted amplification factors are not very sensitive to assumed refractive index of LAC and can be used even in simple models.

A new type of multiple-reflection optical cell is presented. One of the main advantages of this type of cell is that it can be made of standard mirrors without particular tolerance while allowing a great number of reflections and thus a large optical path, only limited by the reflection coefficient of the mirrors. The configuration is simple, compact, stable, and cheap. This cell consists of three mirrors as in a White cell but its principle is different. It behaves as a multiplier of a Herriott cell from which it inherits the opto-mechanical stability qualities. The Herriott cell and the White cell are two particular cases of this type of cell. As examples, a demonstrator and an absorption cell contained in a volume of 5 l are presented. The first device is usable with a laser in visible light. The second device is usable with an infrared laser diode for the detection of atmospheric trace species.

A large area, charge-couple-device (CCD) based fiberoptic taper array detector (APS-1) has been installed at the insertion-device beamline of the Structural Biology Center at the ANL Advanced Photon Source. The detector is used in protein crystallography diffraction experiments, where the objective is to measure the position and intensity of X-ray Bragg peaks in diffraction images. Large imaging area, very high spatial resolution, high X-ray sensitivity, good detective quantum efficiency, low noise, wide dynamic range, excellent stability and short readout time are all fundamental requirements in this application. The APS-1 detector converts the two-dimensional X-ray patterns to a visible light images by a thin layer of Xray sensitive phosphor. The phosphor coating is directly deposited on the large ends of nine fiberoptic tapers arranged in a 3x3 array. Nine; thermoelectrically cooled 1024 x 1024 pixel CCD's image the patterns, demagnified by the tapers. After geometrical and uniformity corrections, the nine areas give a continuous image of the detector face with virtually no gaps between the individual tapers. The 18 parallel analog signal-processing channels and analog-to-digital converters assure short readout time and low readout noise.

Titania, TiO2, irradiated by ultraviolet/visible light was used to mediate the photocatalyzed degradation of ortho-cresol, meta-cresol, and para-cresol. The total photomineralization of these phenols to carbon dioxide and water occurs in air-equilibrated aqueous media. Two major hydroxylated aromatic intermediate species have been identified by liquid chromatographic methods: 4methylcatechol and methylhydroquinone. Photochemical efficiencies (lower limits of quantum yields, 365 nm) of compound disappearance are, respectively, 0.0096, 0.0076, and 0.010 for o-, m-, and p-cresol. The effect of such parameters as pH, initial cresol concentration, and radiant power levels on the degradation of m-cresol was examined in detail. Although the photodegradation process kinetics show similarities with Langmuir-Hinshelwood-type behavior, namely saturation, it is shown that the resulting kinetic expression for the rate of degradation is a complicated function of various parameters and is silent as to the details of the initial photooxidative steps. It is implicitly argued, however, that the reaction takes place on the semiconductor particle surface.

The carbon-doped titania with high surface area was prepared by temperature-programmed carbonization of K-contained anatase titania under a flow of cyclohexane. This carbon-doped titania has much better photocatalytic activity for gas-phase photo-oxidation of benzene under irradiation of artificial solar light than pure titania. The visible light photocatalytic activity is ascribed to the presence of oxygen vacancy states because of the formation of Ti 3+ species between the valence and the conduction bands in the TiO 2 band structure. The co-existence of K and carbonaceous species together stabilize Ti 3+ species and the oxygen vacancy state in the as-synthesized carbon-doped titania.

The effect of prolonged light exposure on the chemical changes in milk stored at 4°C in clear polyethylene terephthalate (PET) bottles was compared with milk stored in green PET bottles, containers made from PET incorporating a UV blocker, PET containers with exterior labels and high-density polyethylene (HDPE) jugs and low-density polyethylene (LDPE) pouches stored under the same conditions. Data were obtained for lipid oxidation, vitamin A degradation, protein hydrolysis, lipolysis and microbial growth. The milk stored in green PET bottles experienced less lipid oxidation and vitamin A loss than milk stored in the clear PET bottles, or the LDPE pouches and jugs. In general, the milk stored in the clear PET bottles was not as well protected from the effects of light as milk stored in green bottles or LDPE pouches. However, during the first week of storage, only vitamin A loss showed a substantial difference between the milk stored in green PET bottles, clear PET bottles or LDPE pouches. The PET bottles with UV blockers slowed vitamin A degradation but had little effect on lipid oxidation. Blocking visible light with translucent labels helped to inhibit lipid oxidation and vitamin A degradation.

The synthesis of Bi 2 O 3 by a simple sonochemical route is investigated. Surfactant polyvinylpyrrolidone (PVP) has strong effects on the grain sizes and morphologies of Bi 2 O 3 . Bi 2 O 3 single crystallite with grain size of 40-100 nm is obtained in the presence of 0.5 g PVP. X-ray diffraction (XRD) pattern shows that the nanocrystallite Bi 2 O 3 is monoclinic and has a high degree of crystallinity. Optical characterizations show that the nanocrystallite Bi 2 O 3 presents the photoabsorption properties from UV light region to visible light shorter than 470 nm and the band gap of the nanocrystallite Bi 2 O 3 is 2.85 eV. The photocatalytic performance of the nanocrystallite Bi 2 O 3 is evaluated using methyl orange (MeO) as a model pollutant. The photocatalytic results show that such nanocrystallite Bi 2 O 3 can effectively degrade 86% MeO within 100 min under visible light illumination (l > 400 nm). The action spectrum of MeO degradation over nanocrystallite Bi 2 O 3 further confirms that the photocatalytic reaction can be driven by visible light. The photocatalytic mechanism is also studied based on electronic structure calculations using density functional theory (DFT). #

Optical observations of the marine environment, giving information on ocean colour, have been increasingly used to provide a novel insight into a number of bio-geochemical and physical processes. The term ocean colour is used to indicate the visible light spectrum as observed at the sea surface that is related, by the processes of absorption and scattering, to the concentration of the water constituents. The feasibility and usefulness of satellite ocean colour remote sensing was first demonstrated by the Coastal Zone Colour Scanner (CZCS) on board Nimbus-7. More than a decade after the pioneer CZCS mission a new generation of ocean colour sensors has emerged. Indian Remote Sensing satellite P4, Ocean Colour Monitor (OCM) belongs to this new generation, and is equipped with channels and a resolution that can cater to the needs of the ocean colour community.

Visible Light Laser Guidestar Experiments (ViLLaGEs) is a new Micro-Electro Mechanical Systems (MEMS) based visible-wavelength adaptive optics (AO) testbed on the Nickel 1-meter telescope at Lick Observatory. Closed loop Natural Guide Star (NGS) experiments were successfully carried out during engineering during the fall of 2007. This is a major evolutionary step, signaling the movement of AO technologies into visible light with a MEMS mirror. With on-sky Strehls in I-band of greater than 20% during second light tests, the science possibilities have become evident. Described here is the advanced engineering used in the design and construction of the ViLLaGEs system, comparing it to the LickAO infrared system, and a discussion of Nickel dome infrastructural improvements necessary for this system. A significant portion of the engineering discussion revolves around the sizable effort that went towards eliminating flexure. Then, we detail upgrades to ViLLaGEs to make it a facility class instrument. These upgrades will focus on Nyquist sampling the diffraction limited point spread function during open loop operations, motorization and automation for technician level alignments, adding dithering capabilities and changes for near infrared science.

Phenology shows sensitive responses to seasonal changes in atmospheric conditions. Forest understory phenology, in particular, is a crucial component of the forest ecosystem that interacts with meteorological factors, and ecosystem functions such as carbon exchange and nutrient cycling. Quantifying understory phenology is challenging due to the multiplicity of species and heterogeneous spatial distribution. The use of digital photography for assessing forest understory phenology was systematically tested in this study within a temperate forest during spring 2007. Five phenology metrics (phenometrics) were extracted from digital photos using three band algebra and two greenness percentage (image binarization) methods. Phenometrics were compared with a comprehensive suite of concurrent meteorological variables. Results show that greenness percentage cover approaches were relatively robust in capturing forest understory green-up. Derived spring phenology of understory plants responded to accumulated air temperature as anticipated, and with dayto-day changes strongly affected by estimated moisture availability. This study suggests that visible-light photo-graphic assessment is useful for efficient forest understory phenology monitoring and allows more comprehensive data collection in support of ecosystem/land surface models.

The influence of visible light on the trigger wave propagation in a thin layer of the Ru(bpy) ]+-catalyzed Belousov-Zhabotiasky reaction is investigated. The velocity evolution of a wave propagating in the dark was followed after switching on the light. The velocity starts to decrease immediately, but a new stationary value is attained only after about 10 s. The inhibitory effect on the propagation velocity was more pronounced in thin reactive layers than in thick ones. The experimental data were compared with computational results obtained with a modified Oregonator model.

Two approaches for harvesting solar light energy effectively using oxide semiconductor materials are introduced. The one is water splitting using new types of oxide semiconductor photocatalyst systems. By Na2CO3 addition method, it was firstly demonstrated that water is decomposed to H2 and O2 steadily and stoichiometrically using NiO/TIO2 photocatalyst under the solar light. A new two-step water splitting system using photocatalysis is also introduced. The other is dyesensitized oxide semiconductor solar cells in order to convert visible light energy to electricity. Combinations of various types of oxide semiconductors and organic dyes, such as Eosin-Y, suggests the appearance of promising and cheap solar cells.

The photocatalytic degradation of fenitrothion under UV and near visible light in the presence of polyoxometallate (POM) photocatalyst PW 12 O 40 3− , in aqueous solutions has been studied and compared with the photodegradation by TiO 2 suspensions. Fenitrothion is effectively degraded in the presence of both photocatalysts following pseudo first order kinetics. Complete mineralization of fenitrothion is achieved using both photocatalysts, leading to the formation of CO 2 and inorganic ions (PO 4 3− , SO 4 2− , NO 2 − , and NO 3 − ) as final products. Various inermediates, identical in the presence of both photocatalysts, have been detected and identified using HPLC and GC-MS techniques. The similarity of the intermediates by these two methods, i.e. PW 12 O 40 3− and TiO 2 tends to suggest, that the photodegradation mechanism of fenitrothion as other cases as well, takes place mainly via a common reagent, i.e. OH radicals. A photodegradation mechanism is proposed.

Silicon is a convenient and inexpensive platform for radiation detection, but has low stopping power for x-rays and gamma-rays with high energy (e.g., 100 keV, as used in computed tomography and digital radiography, or 1 MeV, as desired for detection of nuclear materials). We have effectively increased the stopping power of silicon detectors by producing a layer of porous or micro-machined silicon, and infusing this layer with semiconductor quantum dots made of electron-dense materials. Results of prototype detectors show sensitivity to infrared, visible light, and x-rays, with dark current of less than 1 nA/mm(2).

The TiO 2 /UV photocatalytic degradations of indigo and of indigo carmine have been investigated both in aqueous heterogeneous suspensions and in the solid state. In addition to prompt removal of the color, TiO 2 /UV-based photocatalysis was simultaneously able to oxidize the dye, with almost complete mineralization of carbon and of nitrogen and sulfur heteroatoms into CO 2 , NH + 4 , NO − 3 , and SO 2− 4 , respectively. A detailed degradation pathway has been determined by careful identification of intermediate products, in particular, carboxylic acids, whose decarboxylation by photo-Kolbe reactions constitutes the main source of CO 2 evolution. The only persistent organic compound was acetic acid, whose degradation required a longer period of time. These results suggest that TiO 2 /UV photocatalysis may be envisaged as a method for treatment of diluted wastewaters in textile industries. The irradiation of titania with visible light did produce a photoinduced decolorization of the dye, probably induced by the breaking of the double-bond conjugation system of the chromophoric group. However, this decolorization was not accompanied by any degradation of the molecule since no loss of total organic carbon (TOC) nor release of inorganic ions were observed. This corresponded to a stoichiometric reaction of an electron transfer from the dye molecule excited in visible irradiation to titania. Because indigo is very poorly soluble (≈2 ppm), it was tentatively degraded in its solid state, mixed with titania in a photocatalytic solid-solid-type reaction. Observation of the decolorization and of the degradation of solid indigo constitutes a surprising and encouraging result for the development of self-cleaning titania-coated objects (glasses, steel, aluminium, metals, walls, etc.) fouled by solid dirt particles.

Hydrogen evolution was observed from the noble-metal-free catalyst systems, comprising Rose Bengal, BF xbridged cobaloximes, and triethylamine, in an aqueous solution under irradiation of visible light. Two types of BF x -bridged cobaloximessnamely, the annulated cobaloximes [Co(dmgBF 2 ) 2 (H 2 O) 2 ] (1, dmgBF 2 ) (difluoroboryl)dimethylglyoximate anion) and [Co(dpgBF 2 ) 2 (H 2 O) 2 ] (2, dpgBF 2 ) (difluoroboryl)diphenylglyoximate anion), and the clathrochelated cobaloximes [Co(dmg(BF) 2/3 ) 3 ](BF 4 ) (3) and [Co(dpg(BF) 2/3 ) 3 ](BF 4 ) (4)swere used as catalysts. Among the four cobalt complexes, complex 1 displayed the highest hydrogenevolving efficiency, with turnovers up to 327. Complexes 2 and 4 that bear the diphenylglyoximate ligands exhibited much lower efficiencies as compared with their analogues 1 and 3 that have the dimethylglyoximate ligands. The hydrogen-evolving efficiency of the annulated cobalt(II) complex 1 that contains two labile axial ligands is more than three times as high as that of the encapsulated cobalt(III) complex 3 that has a single macrobicyclic ligand. The different pathways for formation of the cobalt(I) species from these two types of cobaloximes are discussed on the basis of the results obtained from fluorescence and laser flash photolysis spectroscopic studies.

Polyvinyl alcohol (PVA) has been used to prevent flaking of paint pigments on traditional Japanese Shohekiga painted screens and panels. However, over time these PVA coatings whiten. To date, the mechanism of this whitening has not been studied from the point of view of polymer degradation. In this study, a piece of whitened PVA was obtained from a painted wooden panel. The PVA whitening mechanism was studied in this piece using scanning electron microscopy (SEM) and functional group analysis by Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). SEM showed that the surface of the whitened PVA thin film was irregular and rugged, and many micrometer-sized cracks were observed. This suggests that efficient scattering of all visible light from the cracks causes whitening. FT-IR and XPS measurements revealed that inter-and intra-chain dehydration and chemical crosslinking (C-O ether linkage) occur on the surface of the whitened PVA.

Fusion of radar and EO-sensors for the purpose of surveillance is investigated. All sensors are considered to be co-located with respect to the distance of the area under surveillance. More specifically, the applicability for such multi-sensor systems is examined for surveillance in littoral waters. The sensor suite is a coherent polarimetric radar in combination with a set of camera's sensitive in visible light, near infrared, mid infrared and far infrared. A so-called fuse while track algorithm is the best candidate for these dissimilar colocated and not necessarily synchronized sensors.

The photocatalytic bleaching of dyes using TiO2 has appeared promising in laboratory studies, but little attention has been focused on whether other species such as might be found in wastewater have a deleterious effect on the photobleaching. This study describes the effects that result from the presence of ionic species, organic solvents and humic substances on the photobleaching of several dyes. The manner in which the photobleaching was affected by the presence of adventitious materials was carefully examined with an eye toward elucidating the mechanistic origin of the loss of the photochemical efficiency in the reaction. The overall retardation effects can be attributed to the combination of light attenuation, inhibition and competition effects.

The characteristic time constants of the relaxation dynamics of core-excited atoms have hitherto been inferred from the linewidths of electronic transitions measured by continuous-wave extreme ultraviolet or X-ray spectroscopy. Here we demonstrate that a laser-based sampling system, consisting of a few-femtosecond visible light pulse and a synchronized sub-femtosecond soft X-ray pulse, allows us to trace these dynamics directly in the time domain with attosecond resolution. We have measured a lifetime of 7:9 11:0 20:9 fs of M-shell vacancies of krypton in such a pump-probe experiment.

Chemically synthesized single-crystal silver nanoparticles are used to demonstrate plasmon enhanced visible light emission from nitride semiconductor quantum wells. For ease of assembly and testing, the nanoparticles are embedded onto the surface of flexible resin films, which are then simply adhered on top of the light emitting samples. Large enhancements in photoluminescence efficiency are correspondingly measured at emission wavelengths near the nanoparticle plasmonic resonance. At the same time, when samples emitting at a sufficiently far detuned wavelength are used, the measured efficiency is not affected by the nanoparticles, which confirms the plasmonic origin of the observed enhancement.

Chromogenic device technology can be used to vary the throughput of visible light and solar energy for windows in buildings as well as for other see-through applications. The technologies can make use of a range of ''chromic'' materials -such as electrochromic, thermochromic, photochromic, etc -either by themselves or in combinations. The first part of this paper points at the great energy savings that can be achieved by use of chromogenic technologies applied in the built environment, and that these savings can be accomplished jointly with improved indoor comfort for the users of the building. Some recent data are presented on a foil-type electrochromic device incorporating tungsten oxide and nickel oxide. In particular, we consider the possibilities of controlling the near-infrared transmittance and optimize this property for specific climates. To that end we discuss Au-based transparent conductors for electrochromics as well as high-transmittance thermochromic multilayer films incorporating VO 2 and TiO 2 .

Photoredox pairs consisting of selenocarbocyanine dye cations and phenyltrialkylborate anions were employed as the novel, effective visible-wavelength initiators of the radical polymerization of acrylic monomer. The influence of the sensitizers and electron donor structure on the photopolymerization kinetics of multiacrylate monomer was investigated by photo-DSC. It was found that the polymerization rate and the final conversion degree were dependent on both dye and borate structure. The kinetic studies of the free radical polymerization revealed an increase in the polymerization rate with a decrease of the borate oxidation potentials which was additionally reflected by the linear relationship between the Hammett constant and rate of polymerization. The efficiency of these initiators was discussed on the basis of the free energy change for electron transfer from an excited cyanine dye cation to a borate anion.

The effect of inulin on the gelation of 0.5 wt% low acyl gellan in the presence of increasing concentrations of potassium chloride was investigated by large deformation compression experiments and visible light absorbance. The sugar and salt concentrations varied from 0 to 15 wt% and 40-100 mM, respectively. Stress and strain at failure along with Young's modulus were calculated from each compression curve. Samples prior to compression were refrigerated at 5°C for 24 h. Reduced gel strength and firmness were observed for all inulin and salt concentrations. Increasing amounts of inulin resulted in an increase in gel strength which was greater for higher potassium concentrations. Elasticity values did not exhibit great diversion. Inulin at concentrations of 5 and 10 wt% led to less turbid gels than those with only gellan. Samples containing 15 wt% inulin gave absorbance readings greater than 1.

Titanium dioxide represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as antibacterial agent because of strong oxidation activity and superhydrophilicity. TiO 2 shows relatively high reactivity and chemical stability under ultraviolet light ( <387nm), whose energy exceeds the band gap of 3.3 eV in the anatase crystalline phase. The development of photocatalysts exhibiting high reactivity under visible light ( > 400 nm) should allow the main part of the solar spectrum, even under poor illumination of interior lighting, to be used. Visible light-activated TiO 2 could be prepared by metal-ion implantation, reducing of TiO 2 , nonmetal doping or sensitizing of TiO 2 with dyes. This paper reviews preparation methods of doped-TiO 2 with metallic and nonmetallic species, including various types of dopants and doping methods currently available. The mechanism of heterogeneous photocatalysis in the presence of TiO 2 is also discussed. . Mechanism of TiO 2 photocatalysis: hv 1 : pure TiO 2 ; hv 2 : metal-doped TiO 2 and hv 3 : nonmetal-doped TiO 2 .