Sample records for absorptions exploiting photo-thermal

  1. Colour centre recovery in yttria-stabilised zirconia: photo-induced versus thermal processes

    NASA Astrophysics Data System (ADS)

    Costantini, Jean-Marc; Touati, Nadia; Binet, Laurent; Lelong, Gérald; Guillaumet, Maxime; Beuneu, François

    2018-05-01

    The photo-annealing of colour centres in yttria-stabilised zirconia (YSZ) was studied by electron paramagnetic resonance spectroscopy upon UV-ray or laser light illumination, and compared to thermal annealing. Stable hole centres (HCs) were produced in as-grown YSZ single crystals by UV-ray irradiation at room temperature (RT). The HCs produced by 200-MeV Au ion irradiation, as well as the F+-type centres (? centres involving oxygen vacancies) were left unchanged upon UV illumination. In contrast, a significant photo-annealing of the latter point defects was achieved in 1.4-MeV electron-irradiated YSZ by 553-nm laser light irradiation at RT. Almost complete photo-bleaching was achieved by laser irradiation inside the absorption band of ? centres centred at a wavelength 550 nm. Thermal annealing of these colour centres was also followed by UV-visible absorption spectroscopy showing full bleaching at 523 K. Colour-centre evolutions by photo-induced and thermally activated processes are discussed on the basis of charge exchange processes between point defects.

  2. Photo-induced intersubband absorption in {Si}/{SiGe} quantum wells

    NASA Astrophysics Data System (ADS)

    Boucaud, P.; Gao, L.; Visocekas, F.; Moussa, Z.; Lourtioz, J.-M.; Julien, F. H.; Sagnes, I.; Campidelli, Y.; Badoz, P.-A.; Vagos, P.

    1995-12-01

    We have investigated photo-induced intersubband absorption in the valence band of {Si}/{SiGe} quantum wells. Carriers are optically generated in the quantum wells using an argon ion laser. The resulting infrared absorption is probed with a step-scan Fourier transform infrared spectrometer. The photo-induced infrared absorption in SiGe quantum wells is dominated by two contributions: the free carrier absorption, which is similar to bulk absorption in a uniformly doped SiGe layer, and the valence subband absorption in the quantum wells. Both p- and s-polarized intersubband absorptions are measured. We have observed that the photo-induced intersubband absorption in doped samples is shifted to lower energy as compared to direct intersubband absorption. This absorption process is attributed to carriers away from the Brillouin zone center. We show that the photo-induced technique is appropriate to study valence band mixing effects and their influence on intersubband absorption.

  3. Adaptive laser conditioning of reflective thin film based on photo thermal lens probe

    NASA Astrophysics Data System (ADS)

    Liu, Zhichao; Zheng, Yi; Zhang, Qinghua; Pan, Feng; Wei, Yaowei; Wang, Jian; Xu, Qiao

    2017-12-01

    A novel laser conditioning (LC) concept that performs adaptive control of exposure fluence is proposed. As photo-thermal absorption effect can discover defects responsible for laser-induced damage of reflective thin film, in situ photo-thermal lens probe is introduced in conventional LC procedure to detect defects during raster-scanning. The absorptance signal is fed back to guide the adaptive control of exposure fluence. By this method, the damage risk accompanying with LC can be reduced to a rather low level. In order to test the performance of adaptive laser conditioning (ALC), an experimental setup has been built, and several film samples have been tested. The results show that ALC is effective at reducing laser damage risk.

  4. Photo-thermal processing of semiconductor fibers and thin films

    NASA Astrophysics Data System (ADS)

    Gupta, Nishant

    Furnace processing and rapid thermal processing (RTP) have been an integral part of several processing steps in semiconductor manufacturing. The performance of RTP techniques can be improved many times by exploiting quantum photo-effects of UV and vacuum ultraviolet (VUV) photons in thermal processing and this technique is known as rapid photo-thermal processing (RPP). As compared to furnace processing and RTP, RPP provides higher diffusion coefficient, lower stress and lower microscopic defects. In this work, a custom designed automated photo assisted processing system was built from individual parts and an incoherent light source. This photo-assisted processing system is used to anneal silica clad silicon fibers and deposit thin-films. To the best of our knowledge, incoherent light source based rapid photo-thermal processing (RPP) was used for the first time to anneal glass-clad silicon core optical fibers. X-ray diffraction examination, Raman spectroscopy and electrical measurements showed a considerable enhancement of structural and crystalline properties of RPP treated silicon fibers. Photons in UV and vacuum ultraviolet (VUV) regions play a very important role in improving the bulk and carrier transport properties of RPP-treated silicon optical fibers, and the resultant annealing permits a path forward to in situ enhancement of the structure and properties of these new crystalline core optical fibers. To explore further applications of RPP, thin-films of Calcium Copper Titanate (CaCu3Ti4O12) or CCTO and Copper (I) Oxide (Cu2O) were also deposited using photo-assisted metal-organic chemical vapor deposition (MOCVD) on Si/SiO2 and n-Si substrate respectively. CCTO is one of the most researched giant dielectric constant materials in recent years. The given photo-assisted MOCVD approach provided polycrystalline CCTO growth on a SiO2 surface with grain sizes as large as 410 nm. Copper (I) oxide (Cu2O) is a direct band gap semiconductor with p-type conductivity and

  5. Graphene/elastomer composite-based photo-thermal nanopositioners

    PubMed Central

    Loomis, James; Fan, Xiaoming; Khosravi, Farhad; Xu, Peng; Fletcher, Micah; Cohn, Robert W.; Panchapakesan, Balaji

    2013-01-01

    The addition of nanomaterials to polymers can result not only in significant material property improvements, but also assist in creating entirely new composite functionalities. By dispersing graphene nanoplatelets (GNPs) within a polydimethylsiloxane matrix, we show that efficient light absorption by GNPs and subsequent energy transduction to the polymeric chains can be used to controllably produce significant amounts of motion through entropic elasticity of the pre-strained composite. Using dual actuators, a two-axis sub-micron resolution stage was developed, and allowed for two-axis photo-thermal positioning (~100 μm per axis) with 120 nm resolution (feedback sensor limitation), and ~5 μm/s actuation speeds. A PID control loop automatically stabilizes the stage against thermal drift, as well as random thermal-induced position fluctuations (up to the bandwidth of the feedback and position sensor). Maximum actuator efficiency values of ~0.03% were measured, approximately 1000 times greater than recently reported for light-driven polymer systems. PMID:23712601

  6. Advances in photo-thermal infrared imaging microspectroscopy

    NASA Astrophysics Data System (ADS)

    Furstenberg, Robert; Kendziora, Chris; Papantonakis, Michael; Nguyen, Viet; McGill, Andrew

    2013-05-01

    There is a growing need for chemical imaging techniques in many fields of science and technology: forensics, materials science, pharmaceutical and chemical industries, just to name a few. While FTIR micro-spectroscopy is commonly used, its practical resolution limit of about 20 microns or more is often insufficient. Raman micro-spectroscopy provides better spatial resolution (~1 micron), but is not always practical because of samples exhibiting fluorescence or low Raman scattering efficiency. We are developing a non-contact and non-destructive technique we call photo-thermal infrared imaging spectroscopy (PT-IRIS). It involves photo-thermal heating of the sample with a tunable quantum cascade laser and measuring the resulting increase in thermal emission with an infrared detector. Photo-thermal emission spectra resemble FTIR absorbance spectra and can be acquired in both stand-off and microscopy configurations. Furthermore, PT-IRIS allows the acquisition of absorbance-like photo-thermal spectra in a reflected geometry, suitable for field applications and for in-situ study of samples on optically IR-opaque substrates (metals, fabrics, paint, glass etc.). Conventional FTIR microscopes in reflection mode measure the reflectance spectra which are different from absorbance spectra and are usually not catalogued in FTIR spectral libraries. In this paper, we continue developing this new technique. We perform a series of numerical simulations of the laser heating of samples during photo-thermal microscopy. We develop parameterized formulas to help the user pick the appropriate laser illumination power. We also examine the influence of sample geometry on spectral signatures. Finally, we measure and compare photo-thermal and reflectance spectra for two test samples.

  7. Millisecond ordering of block-copolymer films via photo-thermal gradients

    DOE PAGES

    Majewski, Pawel W.; Yager, Kevin G.

    2015-03-12

    For the promise of self-assembly to be realized, processing techniques must be developed that simultaneously enable control of the nanoscale morphology, rapid assembly, and, ideally, the ability to pattern the nanostructure. Here, we demonstrate how photo-thermal gradients can be used to control the ordering of block-copolymer thin films. Highly localized laser heating leads to intense thermal gradients, which induce a thermophoretic force on morphological defects. This increases the ordering kinetics by at least 3 orders-of-magnitude, compared to conventional oven annealing. By simultaneously exploiting the thermal gradients to induce shear fields, we demonstrate uniaxial alignment of a block-copolymer film in lessmore » than a second. Finally, we provide examples of how control of the incident light-field can be used to generate prescribed configurations of block-copolymer nanoscale patterns.« less

  8. Establishment of an in silico phototoxicity prediction method by combining descriptors related to photo-absorption and photo-reaction.

    PubMed

    Haranosono, Yu; Kurata, Masaaki; Sakaki, Hideyuki

    2014-08-01

    One of the mechanisms of phototoxicity is photo-reaction, such as reactive oxygen species (ROS) generation following photo-absorption. We focused on ROS generation and photo-absorption as key-steps, because these key-steps are able to be described by photochemical properties, and these properties are dependent on chemical structure. Photo-reactivity of a compound is described by HOMO-LUMO Gap (HLG), generally. Herein, we showed that HLG can be used as a descriptor of the generation of reactive oxygen species. Moreover, the maximum-conjugated π electron number (PENMC), which we found as a descriptor of photo-absorption, could also predict in vitro phototoxicity. Each descriptor could predict in vitro phototoxicity with 70.0% concordance, but there was un-predicted area found (gray zone). Interestingly, some compounds in each gray zone were not common, indicating that the combination of two descriptors could improve prediction potential. We reset the cut-off lines to define positive zone, negative zone and gray zone for each descriptor. Thereby we overlapped HLG and PENMC in a graph, and divided the total area to nine zones with cut-off lines of each descriptor. The rules to prediction were decided to achieve the best concordance, and the concordances were improved up to 82.8% for self-validation, 81.6% for cross-validation. We found common properties among false positive or negative compounds, photo-reactive structure and photo-allergenic, respectively. In addition, our method could be adapted to compounds rich in structural diversity using only chemical structure without any statistical analysis and complicated calculation.

  9. Photo-thermal characteristics of water-based Fe3O4@SiO2 nanofluid for solar-thermal applications

    NASA Astrophysics Data System (ADS)

    Khashan, Saud; Dagher, Sawsan; Omari, Salahaddin Al; Tit, Nacir; Elnajjar, Emad; Mathew, Bobby; Hilal-Alnaqbi, Ali

    2017-05-01

    This work proposes and demonstrates the novel idea of using Fe3O4@SiO2 core/shell structure nanoparticles (NPs) to improve the solar thermal conversion efficiency. Magnetite (Fe3O4) NPs are synthesized by controlled co-precipitation method. Fe3O4@SiO2 NPs are prepared based on sol-gel approach, then characterized. Water-based Fe3O4@SiO2 nanofluid is prepared and usedto illustrate the photo-thermal conversion characteristics of a solar collector under solar simulator. The temperature rise characteristics of the nanofluids are investigated at different heights of the solar collector, for duration of 300 min, under a solar intensity of 1000 W m-2. The experimental results show that Fe3O4@SiO2 NPs have a core/shell structure with spherical morphology and size of about 400 nm. Fe3O4@SiO2/H2O nanofluid enhances the photo-thermal conversion efficiency compared with base fluid and Fe3O4/H2O nanofluid, since the silica coating improves both the thermodynamic stability of the nanofluid and the light absorption effectiveness of the NPs. At a concentration of 1 mg/1 ml of Fe3O4@SiO2/H2O, and with the utilization of kerosene into the solar collector, and exposure for radiation for 5 min, the photo-thermal conversion efficiency has shown an enhancement at the bottom of the collector of about 32.9% compared to the base fluid.

  10. Diaryl-substituted norbornadienes with red-shifted absorption for molecular solar thermal energy storage.

    PubMed

    Gray, Victor; Lennartson, Anders; Ratanalert, Phasin; Börjesson, Karl; Moth-Poulsen, Kasper

    2014-05-25

    Red-shifting the absorption of norbornadienes (NBDs), into the visible region, enables the photo-isomerization of NBDs to quadricyclanes (QCs) to be driven by sunlight. This is necessary in order to utilize the NBD-QC system for molecular solar thermal (MOST) energy storage. Reported here is a study on five diaryl-substituted norbornadienes. The introduced aryl-groups induce a significant red-shift of the UV/vis absorption spectrum of the norbornadienes, and device experiments using a solar-simulator set-up demonstrate the potential use of these compounds for MOST energy storage.

  11. Photo-Darkening Kinetics and Structural Anisotropic Modifications in the Chalcogenide Glass Arsenic Trisulfide: a Study of Kinetic X-Ray Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jay Min

    1990-08-01

    The purpose of the study is to investigate the mechanisms involved with photo-induced atomic structural modifications in the chalcogenide glass As_2 S_3. This glass exhibits the reversible effects of photo-darkening followed by thermal bleaching. We observed the time behavior of photo-induced properties under the influence of linearly polarized band -gap light. In a macroscopic optical investigation, we monitor optical changes in the photo-darkening process, and in a local structural probe we study kinetic (or time -resolved dispersive) x-ray absorption spectroscopy. Our observations center on kinetic phenomena and structural modifications induced by polarized excitation of lone-pair orbitals in the chalcogenide glass. Experimental results include the following observations: (i) The polarity of the optically induced anisotropy is critically dependent on the intensity and the polarization of the band-gap irradiation beam. (ii) The near edge peak height in x-ray absorption spectra shows subtle but sensitive change during the photo-darkening process. (iii) Photon intensity dependent dichroic kinetics reflect a connection between the optically probed macroscopic property and the x-ray probed local anisotropic structure. Analysis of the x-ray absorption results includes a computer simulation of the polarized absorption spectra. These results suggest that specific structural units tend to orient themselves with respect to the photon polarization. A substantial part of the analysis involves a major effort in dealing with the x-ray kinetic data manipulation and the experimental difficulties caused by a synchrotron instability problem. Based on our observations, we propose a possible mechanism for the observed photo-structural modifications. Through a model of computer relaxed photo-darkening kinetics, we support the notion that a twisting of a specific intermediate range order structure is responsible for local directional variations and global network distortions. In the

  12. Photo-thermal quartz tuning fork excitation for dynamic mode atomic force microscope

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bontempi, Alexia; Teyssieux, Damien; Thiery, Laurent

    2014-10-13

    A photo-thermal excitation of a Quartz Tuning Fork (QTF) for topographic studies is introduced. The non-invasive photo-thermal excitation presents practical advantages compared to QTF mechanical and electrical excitations, including the absence of the anti-resonance and its associated phase rotation. Comparison between our theoretical model and experiments validate that the optical transduction mechanism is a photo-thermal rather than photo-thermoacoustic phenomenon. Topographic maps in the context of near-field microscopy distance control have been achieved to demonstrate the performance of the system.

  13. Photo- and thermally induced property change in Ag diffusion into Ag/As2Se3 thin films

    NASA Astrophysics Data System (ADS)

    Aparimita, Adyasha; Sripan, C.; Ganesan, R.; Naik, Ramakanta

    2018-03-01

    In the present report, we have prepared As2Se3 and bilayer Ag/As2Se3 chalcogenide thin films prepared by thermal evaporation process. The top Ag layer is being diffused into the bottom As2Se3 layer by 532 nm laser irradiation and thermal annealing process. The photo and thermal energy drives the Ag+ ions into the As2Se3 matrix that enhances the formation of As-Se-Ag solid solution which shows the changes of optical properties such as transmission, absorption power, refractive index, and optical band gap. The transmission power drastically decreased for the thermal-induced film than the laser induced one; and the reverse effect is seen for the absorption coefficient. The non-linear refractive index is found to be increased due to the Ag diffusion into As2Se3 film. The indirect allowed optical band gap is being reduced by a significant amount of 0.17 eV (thermal diffusion) and 0.03 eV (photo diffusion) from the Ag/As2Se3 film. The Ag diffusion creates chemical disorderness in the film observed from the two parameters which measures the degree of disorder such as Urbach energy and Tauc parameter. The structural change is not noticed in the studied film as seen from the X-ray diffraction pattern. Scanning electron microscopy and atomic force microscopy investigations showed that the surface morphology was influenced by the diffusion phenomena. The change in optical constants in such type of film can be used in optical waveguides and optical devices.

  14. Photo-induced-heat localization on nanostructured metallic glasses

    NASA Astrophysics Data System (ADS)

    Uzun, Ceren; Kahler, Niloofar; Grave de Peralta, Luis; Kumar, Golden; Bernussi, Ayrton A.

    2017-09-01

    Materials with large photo-thermal energy conversion efficiency are essential for renewable energy applications. Photo-excitation is an effective approach to generate controlled and localized heat at relatively low excitation optical powers. However, lateral heat diffusion to the surrounding illuminated areas accompanied by low photo-thermal energy conversion efficiency remains a challenge for metallic surfaces. Surface nanoengineering has proven to be a successful approach to further absorption and heat generation. Here, we show that pronounced spatial heat localization and high temperatures can be achieved with arrays of amorphous metallic glass nanorods under infrared optical illumination. Thermography measurements revealed marked temperature contrast between illuminated and non-illuminated areas even under low optical power excitation conditions. This attribute allowed for generating legible photo-induced thermal patterns on textured metallic glass surfaces.

  15. THz-circuits driven by photo-thermoelectric, gate-tunable graphene-junctions

    NASA Astrophysics Data System (ADS)

    Brenneis, Andreas; Schade, Felix; Drieschner, Simon; Heimbach, Florian; Karl, Helmut; Garrido, Jose A.; Holleitner, Alexander W.

    2016-10-01

    For future on-chip communication schemes, it is essential to integrate nanoscale materials with an ultrafast optoelectronic functionality into high-frequency circuits. The atomically thin graphene has been widely demonstrated to be suitable for photovoltaic and optoelectronic devices because of its broadband optical absorption and its high electron mobility. Moreover, the ultrafast relaxation of photogenerated charge carriers has been verified in graphene. Here, we show that dual-gated graphene junctions can be functional parts of THz-circuits. As the underlying optoelectronic process, we exploit ultrafast photo-thermoelectric currents. We describe an immediate photo-thermoelectric current of the unbiased device following a femtosecond laser excitation. For a picosecond time-scale after the optical excitation, an additional photo-thermoelectric contribution shows up, which exhibits the fingerprint of a spatially inverted temperature profile. The latter can be understood by the different time-constants and thermal coupling mechanisms of the electron and phonon baths within graphene to the substrate and the metal contacts. The interplay of the processes gives rise to ultrafast electromagnetic transients in high-frequency circuits, and it is equally important for a fundamental understanding of graphene-based ultrafast photodetectors and switches.

  16. THz-circuits driven by photo-thermoelectric, gate-tunable graphene-junctions

    PubMed Central

    Brenneis, Andreas; Schade, Felix; Drieschner, Simon; Heimbach, Florian; Karl, Helmut; Garrido, Jose A.; Holleitner, Alexander W.

    2016-01-01

    For future on-chip communication schemes, it is essential to integrate nanoscale materials with an ultrafast optoelectronic functionality into high-frequency circuits. The atomically thin graphene has been widely demonstrated to be suitable for photovoltaic and optoelectronic devices because of its broadband optical absorption and its high electron mobility. Moreover, the ultrafast relaxation of photogenerated charge carriers has been verified in graphene. Here, we show that dual-gated graphene junctions can be functional parts of THz-circuits. As the underlying optoelectronic process, we exploit ultrafast photo-thermoelectric currents. We describe an immediate photo-thermoelectric current of the unbiased device following a femtosecond laser excitation. For a picosecond time-scale after the optical excitation, an additional photo-thermoelectric contribution shows up, which exhibits the fingerprint of a spatially inverted temperature profile. The latter can be understood by the different time-constants and thermal coupling mechanisms of the electron and phonon baths within graphene to the substrate and the metal contacts. The interplay of the processes gives rise to ultrafast electromagnetic transients in high-frequency circuits, and it is equally important for a fundamental understanding of graphene-based ultrafast photodetectors and switches. PMID:27762291

  17. THz-circuits driven by photo-thermoelectric, gate-tunable graphene-junctions.

    PubMed

    Brenneis, Andreas; Schade, Felix; Drieschner, Simon; Heimbach, Florian; Karl, Helmut; Garrido, Jose A; Holleitner, Alexander W

    2016-10-20

    For future on-chip communication schemes, it is essential to integrate nanoscale materials with an ultrafast optoelectronic functionality into high-frequency circuits. The atomically thin graphene has been widely demonstrated to be suitable for photovoltaic and optoelectronic devices because of its broadband optical absorption and its high electron mobility. Moreover, the ultrafast relaxation of photogenerated charge carriers has been verified in graphene. Here, we show that dual-gated graphene junctions can be functional parts of THz-circuits. As the underlying optoelectronic process, we exploit ultrafast photo-thermoelectric currents. We describe an immediate photo-thermoelectric current of the unbiased device following a femtosecond laser excitation. For a picosecond time-scale after the optical excitation, an additional photo-thermoelectric contribution shows up, which exhibits the fingerprint of a spatially inverted temperature profile. The latter can be understood by the different time-constants and thermal coupling mechanisms of the electron and phonon baths within graphene to the substrate and the metal contacts. The interplay of the processes gives rise to ultrafast electromagnetic transients in high-frequency circuits, and it is equally important for a fundamental understanding of graphene-based ultrafast photodetectors and switches.

  18. Resonant Absorption in GaAs-Based Nanowires by Means of Photo-Acoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Petronijevic, E.; Leahu, G.; Belardini, A.; Centini, M.; Li Voti, R.; Hakkarainen, T.; Koivusalo, E.; Guina, M.; Sibilia, C.

    2018-03-01

    Semiconductor nanowires made of high refractive index materials can couple the incoming light to specific waveguide modes that offer resonant absorption enhancement under the bandgap wavelength, essential for light harvesting, lasing and detection applications. Moreover, the non-trivial ellipticity of such modes can offer near field interactions with chiral molecules, governed by near chiral field. These modes are therefore very important to detect. Here, we present the photo-acoustic spectroscopy as a low-cost, reliable, sensitive and scattering-free tool to measure the spectral position and absorption efficiency of these modes. The investigated samples are hexagonal nanowires with GaAs core; the fabrication by means of lithography-free molecular beam epitaxy provides controllable and uniform dimensions that allow for the excitation of the fundamental resonant mode around 800 nm. We show that the modulation frequency increase leads to the discrimination of the resonant mode absorption from the overall absorption of the substrate. As the experimental data are in great agreement with numerical simulations, the design can be optimized and followed by photo-acoustic characterization for a specific application.

  19. Oxygen vacancy mediated enhanced photo-absorption from ZnO(0001) nanostructures fabricated by atom beam sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Solanki, Vanaraj; Joshi, Shalik R.; Mishra, Indrani

    2016-08-07

    The nanoscale patterns created on the ZnO(0001) surfaces during atom beam irradiation have been investigated here for their photo absorption response. Preferential sputtering, during irradiation, promotes Zn-rich zones that serve as the nucleation centers for the spontaneous creation of nanostructures. Nanostructured surfaces with bigger (78 nm) nanodots, displaying hexagonal ordering and long ranged periodic behavior, show higher photo absorption and a ∼0.09 eV reduced bandgap. These nanostructures also demonstrate higher concentration of oxygen vacancies which are crucial for these results. The enhanced photo-response, as observed here, has been achieved in the absence of any dopant elements.

  20. Thermally induced nonlinear optical absorption in metamaterial perfect absorbers

    NASA Astrophysics Data System (ADS)

    Guddala, Sriram; Kumar, Raghwendra; Ramakrishna, S. Anantha

    2015-03-01

    A metamaterial perfect absorber consisting of a tri-layer (Al/ZnS/Al) metal-dielectric-metal system with top aluminium nano-disks was fabricated by laser-interference lithography and lift-off processing. The metamaterial absorber had peak resonant absorbance at 1090 nm and showed nonlinear absorption for 600ps laser pulses at 1064 nm wavelength. A nonlinear saturation of reflectance was measured to be dependent on the average laser power incident and not the peak laser intensity. The nonlinear behaviour is shown to arise from the heating due to the absorbed radiation and photo-thermal changes in the dielectric properties of aluminium. The metamaterial absorber is seen to be damage resistant at large laser intensities of 25 MW/cm2.

  1. Photo, thermal and chemical degradation of riboflavin

    PubMed Central

    Kazi, Sadia Hafeez; Ahmed, Sofia; Anwar, Zubair; Ahmad, Iqbal

    2014-01-01

    Summary Riboflavin (RF), also known as vitamin B2, belongs to the class of water-soluble vitamins and is widely present in a variety of food products. It is sensitive to light and high temperature, and therefore, needs a consideration of these factors for its stability in food products and pharmaceutical preparations. A number of other factors have also been identified that affect the stability of RF. These factors include radiation source, its intensity and wavelength, pH, presence of oxygen, buffer concentration and ionic strength, solvent polarity and viscosity, and use of stabilizers and complexing agents. A detailed review of the literature in this field has been made and all those factors that affect the photo, thermal and chemical degradation of RF have been discussed. RF undergoes degradation through several mechanisms and an understanding of the mode of photo- and thermal degradation of RF may help in the stabilization of the vitamin. A general scheme for the photodegradation of RF is presented. PMID:25246959

  2. X-ray-induced photo-chemistry and X-ray absorption spectroscopy of biological samples

    PubMed Central

    George, Graham N.; Pickering, Ingrid J.; Pushie, M. Jake; Nienaber, Kurt; Hackett, Mark J.; Ascone, Isabella; Hedman, Britt; Hodgson, Keith O.; Aitken, Jade B.; Levina, Aviva; Glover, Christopher; Lay, Peter A.

    2012-01-01

    As synchrotron light sources and optics deliver greater photon flux on samples, X-ray-induced photo-chemistry is increasingly encountered in X-ray absorption spectroscopy (XAS) experiments. The resulting problems are particularly pronounced for biological XAS experiments. This is because biological samples are very often quite dilute and therefore require signal averaging to achieve adequate signal-to-noise ratios, with correspondingly greater exposures to the X-ray beam. This paper reviews the origins of photo-reduction and photo-oxidation, the impact that they can have on active site structure, and the methods that can be used to provide relief from X-ray-induced photo-chemical artifacts. PMID:23093745

  3. Photo-thermal modulation of surface plasmon polariton propagation at telecommunication wavelengths.

    PubMed

    Kaya, S; Weeber, J-C; Zacharatos, F; Hassan, K; Bernardin, T; Cluzel, B; Fatome, J; Finot, C

    2013-09-23

    We report on photo-thermal modulation of thin film surface plasmon polaritons (SPP) excited at telecom wavelengths and traveling at a gold/air interface. By operating a modulated continuous-wave or a Q-switched nanosecond pump laser, we investigate the photo-thermally induced modulation of SPP propagation mediated by the temperature-dependent ohmic losses in the gold film. We use a fiber-to-fiber characterization set-up to measure accurately the modulation depth of the SPP signal under photo-thermal excitation. On the basis of these measurements, we extract the thermo-plasmonic coefficient of the SPP mode defined as the temperature derivative of the SPP damping constant. Next, we introduce a figure of merit which is relevant to characterize the impact of temperature onto the properties of bounded or weakly leaky SPP modes supported by a given metal at a given wavelength. By combining our measurements with tabulated values of the temperature-dependent imaginary part of gold dielectric function, we compute the thermo-optical coefficients (TOC) of gold at telecom wavelengths. Finally, we investigate a pulsed photo-thermal excitation of the SPP in the nanosecond regime. The experimental SPP depth of modulation obtained in this situation are found to be in fair agreement with the modulation depths computed by using our values of gold TOC.

  4. Solar absorptance and thermal emittance of some common spacecraft thermal-control coatings

    NASA Technical Reports Server (NTRS)

    Henninger, J. H.

    1984-01-01

    Solar absorptance and thermal emittance of spacecraft materials are critical parameters in determining spacecraft temperature control. Because thickness, surface preparation, coatings formulation, manufacturing techniques, etc. affect these parameters, it is usually necessary to measure the absorptance and emittance of materials before they are used. Absorptance and emittance data for many common types of thermal control coatings, are together with some sample spectral data curves of absorptance. In some cases for which ultraviolet and particle radiation data are available, the degraded absorptance and emittance values are also listed.

  5. Absorption and Emission Spectroscopic Investigation of Thermal Dynamics and Photo-Dynamics of the Rhodopsin Domain of the Rhodopsin-Guanylyl Cyclase from the Nematophagous Fungus Catenaria anguillulae

    PubMed Central

    Penzkofer, Alfons; Scheib, Ulrike; Stehfest, Katja; Hegemann, Peter

    2017-01-01

    The rhodopsin-guanylyl cyclase from the nematophagous fungus Catenaria anguillulae belongs to a recently discovered class of enzymerhodopsins and may find application as a tool in optogenetics. Here the rhodopsin domain CaRh of the rhodopsin-guanylyl cyclase from Catenaria anguillulae was studied by absorption and emission spectroscopic methods. The absorption cross-section spectrum and excitation wavelength dependent fluorescence quantum distributions of CaRh samples were determined (first absorption band in the green spectral region). The thermal stability of CaRh was studied by long-time attenuation measurements at room temperature (20.5 °C) and refrigerator temperature of 3.5 °C. The apparent melting temperature of CaRh was determined by stepwise sample heating up and cooling down (obtained apparent melting temperature: 62 ± 2 °C). The photocycle dynamics of CaRh was investigated by sample excitation to the first inhomogeneous absorption band of the CaRhda dark-adapted state around 590 nm (long-wavelength tail), 530 nm (central region) and 470 nm (short-wavelength tail) and following the absorption spectra development during exposure and after exposure (time resolution 0.0125 s). The original protonated retinal Schiff base PRSBall-trans in CaRhda photo-converted reversibly to protonated retinal Schiff base PRSBall-trans,la1 with restructured surroundings (CaRhla1 light-adapted state, slightly blue-shifted and broadened first absorption band, recovery to CaRhda with time constant of 0.8 s) and deprotonated retinal Schiff base RSB13-cis (CaRhla2 light-adapted state, first absorption band in violet to near ultraviolet spectral region, recovery to CaRhda with time constant of 0.35 s). Long-time light exposure of light-adapted CaRhla1 around 590, 530 and 470 nm caused low-efficient irreversible degradation to photoproducts CaRhprod. Schemes of the primary photocycle dynamics of CaRhda and the secondary photocycle dynamics of CaRhla1 are developed. PMID:28981475

  6. Image processing with the radial Hilbert transform of photo-thermal imaging for carious detection

    NASA Astrophysics Data System (ADS)

    El-Sharkawy, Yasser H.

    2014-03-01

    Knowledge of heat transfer in biological bodies has many diagnostic and therapeutic applications involving either raising or lowering of temperature, and often requires precise monitoring of the spatial distribution of thermal histories that are produced during a treatment protocol. The present paper therefore aims to design and implementation of laser therapeutic and imaging system used for carious tracking and drilling by develop a mathematical algorithm using Hilbert transform for edge detection of photo-thermal imaging. photothermal imaging has the ability to penetrate and yield information about an opaque medium well beyond the range of conventional optical imaging. Owing to this ability, Q- switching Nd:YAG laser at wavelength 1064 nm has been extensively used in human teeth to study the sub-surface deposition of laser radiation. The high absorption coefficient of the carious rather than normal region rise its temperature generating IR thermal radiation captured by high resolution thermal camera. Changing the pulse repetition frequency of the laser pulses affects the penetration depth of the laser, which can provide three-dimensional (3D) images in arbitrary planes and allow imaging deep within a solid tissue.

  7. Influence of photo- and thermal bleaching on pre-irradiation low water peak single mode fibers

    NASA Astrophysics Data System (ADS)

    Yin, Jianchong; Wen, Jianxiang; Luo, Wenyun; Xiao, Zhongyin; Chen, Zhenyi; Wang, Tingyun

    2011-12-01

    Reducing the radiation-induced transmission loss in low water peak single mode fiber (LWP SMF) has been investigated by using photo-bleaching method with 980nm pump light source and using thermal-bleaching method with temperature control system. The results show that the radiation-induced loss of pre-irradiation optical fiber can be reduced effectively with the help of photo-bleaching or thermal-bleaching. Although the effort of photo-bleaching is not as significant as thermal-bleaching, by using photo-bleaching method, the loss of fiber caused by radiation-induced defects can be reduced best up to 49% at 1310nm and 28% at 1550nm in low pre-irradiation condition, the coating of the fiber are not destroyed, and the rehabilitating time is just several hours, while self-annealing usually costs months' time. What's more, the typical high power LASER for photo-bleaching can be 980nm pump Laser Diode, which is very accessible.

  8. Character of skin on photo-thermal response and its regeneration process using second-harmonic generation microscopy.

    PubMed

    Wu, Shu-lian; Li, Hui; Zhang, Xiao-man; Chen, Wei R; Wang, Yun-Xia

    2014-01-01

    Quantitative characterization of skin collagen on photo-thermal response and its regeneration process is an important but difficult task. In this study, morphology and spectrum characteristics of collagen during photo-thermal response and its light-induced remodeling process were obtained by second-harmonic generation microscope in vivo. The texture feature of collagen orientation index and fractal dimension was extracted by image processing. The aim of this study is to detect the information hidden in skin texture during the process of photo-thermal response and its regeneration. The quantitative relations between injured collagen and texture feature were established for further analysis of the injured characteristics. Our results show that it is feasible to determine the main impacts of phototherapy on the skin. It is important to understand the process of collagen remodeling after photo-thermal injuries from texture feature.

  9. Thermal and photo-stability of the antioxidant potential of Spirulina platensis powder.

    PubMed

    Colla, L M; Bertol, C D; Ferreira, D J; Bavaresco, J; Costa, J A V; Bertolin, T E

    2017-01-01

    This work aimed to evaluate the thermal and photo stability of the antioxidant potential (AP) of the Spirulina platensis biomass. Thermal stability was established at 25ºC, 40ºC and 50ºC for 60 days, in the dark, protected from light. Photo stability was evaluated using UV (15 W, λ = 265 nm) and fluorescent (20 W, 0.16 A, power factor FP > 0.5, 50/60 Hz, 60 lm/w, 1200 lm) light for 90 days in capsules, glass and Petri dishes, at room temperature. The AP of the biomass in these conditions was determined at intervals (every 7 and 30 days in the studies of thermal and photo stability, respectively) using the induction of the oxidation of a lipid system by heat and aeration. In this lipid system, the biomass submitted to degradation was used as an antioxidant. The kinetics of the reaction was determined by the Arrhenius method. Thermal degradation was found to follow zero order kinetics, whereas photo degradation followed first order kinetics. The AP decreased 50% after 50 days at 25°C. At 40°C and 50°C, the AP decreased more than 50% after 35 and 21 days of exposition, respectively. The decrease of the AP of Spirulina was more sensible to UV and fluorescence light. After 30 days of exposition, the AP decreased more than 50% in all storage conditions tested. The antioxidant potential of Spirulina platensis is easily degraded when the biomass is exposed to heat and light, indicating the need for care to be taken in its storage.

  10. Compton scattering from nuclei and photo-absorption sum rules

    NASA Astrophysics Data System (ADS)

    Gorchtein, Mikhail; Hobbs, Timothy; Londergan, J. Timothy; Szczepaniak, Adam P.

    2011-12-01

    We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new “constituent quark model” sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude on constituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition, we extract the α=0 pole contribution for both proton and nuclei. Using the modern high-energy proton data, we find that the α=0 pole contribution differs significantly from the Thomson term, in contrast with the original findings by Damashek and Gilman.

  11. Thermal and photo-thermal PROX reaction over Ag/SiO2 catalysts

    NASA Astrophysics Data System (ADS)

    Sabinas-Hernández, S. A.; Romero-Núñez, A.; Díaz, G.

    2018-02-01

    The effect of plasmonic excitation of Ag/SiO2 catalysts was studied in the preferential CO oxidation in presence of H2 (PROX) at low temperature. Catalysts with 5 wt% silver loading were prepared by wet impregnation in aqueous and basic media. TEM analysis indicates the presence of Ag nanoparticles with a broad particle size distribution which can achieve both, good PROX activity at low temperature and plasmonic interaction with visible light. Photo-assisted reaction at 35 °C enhance CO and O2 conversions; however, the greater improvement was found for O2 conversion. The selectivity towards CO2 decrease when reaction took place under photo-thermal conditions. Occurrence of different silver species and particle size changed after reaction as evidenced by DRS-UV-vis and TEM.

  12. Photo-physical properties and triplet-triplet absorption of platinum(II) acetylides in solid PMMA matrices

    NASA Astrophysics Data System (ADS)

    Glimsdal, Eirik; Westlund, Robert; Lindgren, Mikael

    2009-05-01

    Because of their strong nonlinear optical properties, Platinum(II) acetylides are investigated as potential chromophores for optical power limiting (OPL) applications. The strong excited state absorption and efficient intersystem crossing to the triplet states in these materials are desired properties for good OPL performance. We recently reported on OPL and photo-physical properties of Pt(II)-acetylide chromophores in solution, modified with thiophenyl or triazole groups. [R. Westlund et al. J. Mater. Chem. 18, 166 (2008); E. Glimsdal et al. Proc. SPIE 6740, 67400M (2007)] The chromophores were later incorporated into poly(methyl-methacrylate) (PMMA) glasses. A variety of doped organic solids were prepared, reaching concentrations of up to 13 wt% of the guest molecule. Raman spectra of the doped solid devices proved that the chemical structure of the nonlinear dyes remains intact upon the polymerization of the solid matrix. Luminescence spectra confirm that the basic photo-physical properties (absorption, emission and inter-system crossing) observed for the solute molecules in THF are maintained also in the solid state. In particular, the phosphorescence lifetime stays in the order of μs to ms, just as in the oxygen evacuated liquid samples. Also, the wavelength dependence and time-dynamics of the triplet absorption spectra of the dyes, dissolved in THF solution and dispersed in solid PMMA matrices, were investigated and compared. Ground state UV absorption spectra between 300 and 420 nm have corresponding broad band visible triplet-triplet absorption between 400 and 800 nm. The triplet state extinction coefficients were determined to be in the order of 104 M-1cm-1.

  13. Compton Scattering and Photo-absorption Sum Rules on Nuclei

    NASA Astrophysics Data System (ADS)

    Gorshteyn, Mikhail; Hobbs, Timothy; Londergan, J. Timothy; Szczepaniak, Adam P.

    2012-03-01

    We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new ``constituent quark model'' sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude on constituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition we extract the J=0 pole contribution for both proton and nuclei. Using the modern high energy proton data we find that the J=0 pole contribution differs significantly from the Thomson term, in contrast with the original findings by Damashek and Gilman. We discuss phenomenological implications of this new result.

  14. Pathway for recovery of photo-degraded polymer solar cells by post degradation thermal anneal

    DOE PAGES

    Bhattacharya, J.; Joshi, P. H.; Biswas, Rana; ...

    2017-02-16

    The photo-degradation of polymer solar cells is a critical challenge preventing its commercial deployment. We experimentally fabricate organic solar cells and characterize their degradation under solar simulators in an environmental chamber under nitrogen flow, without exposure to oxygen and moisture. We have developed a thermally stable inverted organic solar cell architecture in which light induced degradation of device characteristics can be reversibly annealed to the pristine values. The stable inverted cells utilized MoO x layers that are thermally treated immediately after their deposition on the organic layer, and before metal cathode deposition. Organic solar cells that are photo-degraded in themore » presence of oxygen, however show irreversible degradation that cannot be thermally recovered. The decrease of organic solar cell characteristics correlates with increases in mid-gap electronic states, measured using capacitance spectroscopy and dark current. It is likely the photo-induced defect states caused by local H motion from the alkyl chains to the aromatic backbone, can be reversibly annealed at elevated temperatures after photo-degradation. Finally, our results provide a pathway for improving the stability of organic photovoltaics.« less

  15. Pathway for recovery of photo-degraded polymer solar cells by post degradation thermal anneal

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bhattacharya, J.; Joshi, P. H.; Biswas, Rana

    The photo-degradation of polymer solar cells is a critical challenge preventing its commercial deployment. We experimentally fabricate organic solar cells and characterize their degradation under solar simulators in an environmental chamber under nitrogen flow, without exposure to oxygen and moisture. We have developed a thermally stable inverted organic solar cell architecture in which light induced degradation of device characteristics can be reversibly annealed to the pristine values. The stable inverted cells utilized MoO x layers that are thermally treated immediately after their deposition on the organic layer, and before metal cathode deposition. Organic solar cells that are photo-degraded in themore » presence of oxygen, however show irreversible degradation that cannot be thermally recovered. The decrease of organic solar cell characteristics correlates with increases in mid-gap electronic states, measured using capacitance spectroscopy and dark current. It is likely the photo-induced defect states caused by local H motion from the alkyl chains to the aromatic backbone, can be reversibly annealed at elevated temperatures after photo-degradation. Finally, our results provide a pathway for improving the stability of organic photovoltaics.« less

  16. Photo-thermal and cytotoxic properties of inkjet-printed copper sulfide films on biocompatible latex coated substrates

    NASA Astrophysics Data System (ADS)

    Sarfraz, Jawad; Borzenkov, Mykola; Niemelä, Erik; Weinberger, Christian; Törngren, Björn; Rosqvist, Emil; Collini, Maddalena; Pallavicini, Piersandro; Eriksson, John; Peltonen, Jouko; Ihalainen, Petri; Chirico, Giuseppe

    2018-03-01

    Inkjet-printing of metal nanoparticles is a particularly promising technique for the fabrication and modification of surfaces with a multifunctional nature. Recently copper sulfide nanoparticles (CuS NPs) have attracted wide interest due to a range of valuable properties including long term stability, photo-thermal activity, ease of synthesis and low cost. In the present study, printed CuS patterns were successfully fabricated on latex coated paper substrates and characterized by means of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), UV-Vis-NIR spectroscopy, and grazing incidence X-ray diffraction (GID). The resulted patterns displayed pronounced photo-thermal effect under Near Infrared Irradiation (NIR) even with relatively low laser power. Finally, by utilizing an automated real-time imaging platform it was possible to verify that the CuS printed film was not cytotoxic to human dermal fibroblast cells (HDF). The pronounced photo-thermal properties and nontoxic nature of these printed low-cost flexible CuS films make them promising candidates for fabrication of devices with localized photo-thermal effect suitable for biomedical applications.

  17. Photo-oxidation of Nitrophenols in the Aqueous Phase: Reaction Kinetics, Mechanistic Insights, and Evolution of Light Absorption

    NASA Astrophysics Data System (ADS)

    Hems, R.; Abbatt, J.

    2017-12-01

    Nitrophenols are a class of water soluble, light absorbing compounds which can make up a significant fraction of biomass burning brown carbon. The atmospheric lifetime and aging of these compounds can have important implications for their impact on climate through the aerosol direct effect. Recent studies have shown that brown carbon aerosols can be bleached of their colour by direct photolysis and photo-oxidation reactions on the timescale of hours to days. However, during aqueous phase photo-oxidation of nitrophenol compounds light absorption is sustained or enhanced, even after the parent nitrophenol molecule has been depleted. In this work, we use online aerosol chemical ionization mass spectrometry (aerosol-CIMS) to investigate the aqueous phase photo-oxidation mechanism and determine the second order rate constants for the reaction of OH radicals with three commonly detected nitrophenol compounds: nitrocatechol, nitroguaiacol, and dinitrophenol. These nitrophenol compounds are found to have aqueous phase lifetimes with respect to oxidation by the OH radical ranging between 5 - 11 hours. Our results indicate that functionalization of the parent nitrophenol molecule by addition of hydroxyl groups leads to the observed absorption enhancement. Further photo-oxidation forms breakdown products that no longer absorb significantly in the visible light range.

  18. Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA): New Insights and Opportunities.

    PubMed

    Yeow, Jonathan; Boyer, Cyrille

    2017-07-01

    The polymerization-induced self-assembly (PISA) process is a useful synthetic tool for the efficient synthesis of polymeric nanoparticles of different morphologies. Recently, studies on visible light initiated PISA processes have offered a number of key research opportunities that are not readily accessible using traditional thermally initiated systems. For example, visible light mediated PISA (Photo-PISA) enables a high degree of control over the dispersion polymerization process by manipulation of the wavelength and intensity of incident light. In some cases, the final nanoparticle morphology of a single formulation can be modulated by simple manipulation of these externally controlled parameters. In addition, temporal (and in principle spatial) control over the Photo-PISA process can be achieved in most cases. Exploitation of the mild room temperature polymerizations conditions can enable the encapsulation of thermally sensitive therapeutics to occur without compromising the polymerization rate and their activities. Finally, the Photo-PISA process can enable further mechanistic insights into the morphological evolution of nanoparticle formation such as the effects of temperature on the self-assembly process. The purpose of this mini-review is therefore to examine some of these recent advances that have been made in Photo-PISA processes, particularly in light of the specific advantages that may exist in comparison with conventional thermally initiated systems.

  19. Thermal Boundary Layer Effects on Line-of-Sight Tunable Diode Laser Absorption Spectroscopy (TDLAS) Gas Concentration Measurements.

    PubMed

    Qu, Zhechao; Werhahn, Olav; Ebert, Volker

    2018-06-01

    The effects of thermal boundary layers on tunable diode laser absorption spectroscopy (TDLAS) measurement results must be quantified when using the line-of-sight (LOS) TDLAS under conditions with spatial temperature gradient. In this paper, a new methodology based on spectral simulation is presented quantifying the LOS TDLAS measurement deviation under conditions with thermal boundary layers. The effects of different temperature gradients and thermal boundary layer thickness on spectral collisional widths and gas concentration measurements are quantified. A CO 2 TDLAS spectrometer, which has two gas cells to generate the spatial temperature gradients, was employed to validate the simulation results. The measured deviations and LOS averaged collisional widths are in very good agreement with the simulated results for conditions with different temperature gradients. We demonstrate quantification of thermal boundary layers' thickness with proposed method by exploitation of the LOS averaged the collisional width of the path-integrated spectrum.

  20. One-step fabrication of submicrostructures by low one-photon absorption direct laser writing technique with local thermal effect

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nguyen, Dam Thuy Trang; Tong, Quang Cong; Ledoux-Rak, Isabelle

    In this work, local thermal effect induced by a continuous-wave laser has been investigated and exploited to optimize the low one-photon absorption (LOPA) direct laser writing (DLW) technique for fabrication of polymer-based microstructures. It was demonstrated that the temperature of excited SU8 photoresist at the focusing area increases to above 100 °C due to high excitation intensity and becomes stable at that temperature thanks to the use of a continuous-wave laser at 532 nm-wavelength. This optically induced thermal effect immediately completes the crosslinking process at the photopolymerized region, allowing obtain desired structures without using the conventional post-exposure bake (PEB) step, which ismore » usually realized after the exposure. Theoretical calculation of the temperature distribution induced by local optical excitation using finite element method confirmed the experimental results. LOPA-based DLW technique combined with optically induced thermal effect (local PEB) shows great advantages over the traditional PEB, such as simple, short fabrication time, high resolution. In particular, it allowed the overcoming of the accumulation effect inherently existed in optical lithography by one-photon absorption process, resulting in small and uniform structures with very short lattice constant.« less

  1. One-step fabrication of submicrostructures by low one-photon absorption direct laser writing technique with local thermal effect

    NASA Astrophysics Data System (ADS)

    Nguyen, Dam Thuy Trang; Tong, Quang Cong; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

    2016-01-01

    In this work, local thermal effect induced by a continuous-wave laser has been investigated and exploited to optimize the low one-photon absorption (LOPA) direct laser writing (DLW) technique for fabrication of polymer-based microstructures. It was demonstrated that the temperature of excited SU8 photoresist at the focusing area increases to above 100 °C due to high excitation intensity and becomes stable at that temperature thanks to the use of a continuous-wave laser at 532 nm-wavelength. This optically induced thermal effect immediately completes the crosslinking process at the photopolymerized region, allowing obtain desired structures without using the conventional post-exposure bake (PEB) step, which is usually realized after the exposure. Theoretical calculation of the temperature distribution induced by local optical excitation using finite element method confirmed the experimental results. LOPA-based DLW technique combined with optically induced thermal effect (local PEB) shows great advantages over the traditional PEB, such as simple, short fabrication time, high resolution. In particular, it allowed the overcoming of the accumulation effect inherently existed in optical lithography by one-photon absorption process, resulting in small and uniform structures with very short lattice constant.

  2. Diel horizontal migration in streams: juvenile fish exploit spatial heterogeneity in thermal and trophic resources

    USGS Publications Warehouse

    Armstrong, Jonathan B.; Schindler, Daniel E.; Ruff, Casey P.; Brooks, Gabriel T.; Bentley, Kale E.; Torgersen, Christian E.

    2013-01-01

    Vertical heterogeneity in the physical characteristics of lakes and oceans is ecologically salient and exploited by a wide range of taxa through diel vertical migration to enhance their growth and survival. Whether analogous behaviors exploit horizontal habitat heterogeneity in streams is largely unknown. We investigated fish movement behavior at daily timescales to explore how individuals integrated across spatial variation in food abundance and water temperature. Juvenile coho salmon made feeding forays into cold habitats with abundant food, and then moved long distances (350–1300 m) to warmer habitats that accelerated their metabolism and increased their assimilative capacity. This behavioral thermoregulation enabled fish to mitigate trade-offs between trophic and thermal resources by exploiting thermal heterogeneity. Fish that exploited thermal heterogeneity grew at substantially faster rates than did individuals that assumed other behaviors. Our results provide empirical support for the importance of thermal diversity in lotic systems, and emphasize the importance of considering interactions between animal behavior and habitat heterogeneity when managing and restoring ecosystems.

  3. 3D exploitation of large urban photo archives

    NASA Astrophysics Data System (ADS)

    Cho, Peter; Snavely, Noah; Anderson, Ross

    2010-04-01

    Recent work in computer vision has demonstrated the potential to automatically recover camera and scene geometry from large collections of uncooperatively-collected photos. At the same time, aerial ladar and Geographic Information System (GIS) data are becoming more readily accessible. In this paper, we present a system for fusing these data sources in order to transfer 3D and GIS information into outdoor urban imagery. Applying this system to 1000+ pictures shot of the lower Manhattan skyline and the Statue of Liberty, we present two proof-of-concept examples of geometry-based photo enhancement which are difficult to perform via conventional image processing: feature annotation and image-based querying. In these examples, high-level knowledge projects from 3D world-space into georegistered 2D image planes and/or propagates between different photos. Such automatic capabilities lay the groundwork for future real-time labeling of imagery shot in complex city environments by mobile smart phones.

  4. Rheological characterization of thermal, thermo-oxidative and photo-oxidative degradation of LDPE

    NASA Astrophysics Data System (ADS)

    Rolón-Garrido, Víctor Hugo; Wagner, Manfred Hermann

    2015-04-01

    Rheology has been used to study thermal degradation (V. H. Rolón-Garrido et al., Rheol. Acta 50, 519-535, 2011), thermo-oxidative degradation (V. H. Rolón-Garrido et al., Rheol. Acta 50, 519-535, 2011; V. H. Rolón-Garrido et al., J. Rheol. 57, 105-129, 2013) and photo-oxidative degradation (V. H. Rolón-Garrido and M. H. Wagner, Polym. Degrad. Stab. 99, 136-145, 2014; V. H. Rolón-Garrido and M. H. Wagner, J. Rheol. 58, 199-22 2, 2014; V. H. Rolón-Garrido et al., Polym. Degrad. Stab. 111, 46-54, 2015) of low-density polyethylene (LDPE). This contribution presents the analogies and differences between these types of degradations of LDPE on the linear (by use of van-Gurp Palmen plots) and non-linear viscoelastic properties (by use of the parameters of the MSF model, fmax2 and β), as well as on the failure mode of the samples (through the maximum strain and stress achieved experimentally). In contrast to thermal and thermo-oxidative degradation, the linear viscoelastic properties of photo-oxidated samples were more affected by degradation. In the non-linear regime, for thermal and thermo-oxidative treated samples, the elongational measurements elucidated the role of chain scission and long-chain branching (LCB) formation, while for photo-oxidated LDPE even the competition between chain scission, LCB formation, and gel formation was demonstrated. The failure behavior was found to be determined by a constant maximum strain in thermo-oxidative degradation, if the LDPE has high content in branching points, or in photo-oxidative degraded LDPE, if a considerable portion of gel structure is present. Otherwise, either the maximum strain or stress measured was found to be strain-rate dependent.

  5. Unusual infrared absorption increases in photo-degraded organic films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shah, Satvik; Biswas, Rana; Koschny, Thomas

    Degradation is among the most pressing problems facing organic materials, occurring through ingress of moisture and oxygen, and light exposure. We determine the nanoscale pathways underlying degradation by light-soaking organic films in an environmental chamber, and performing infrared spectroscopy, to identify atomic bonding changes. We utilize as a prototype the low band gap PTB7-PCBM blend. Films light-soaked in the presence of oxygen show unusual increased absorption at 1727 cm –1 attributable to increased C=O modes, and a broad increase at 3240 cm –1 attributable to hydroxyl (O–H) groups bonded within the organic matrix. Films exposed to oxygen in the dark,more » or light-soaked in an inert atmosphere, do not exhibit significant absorption changes, suggesting simultaneous exposure of oxygen and light that creates singlet excited oxygen is the detrimental factor. Our ab initio electronic structure simulations interpret these by oxidation at the α-C site of the alkyl chains in PTB7, with an irreversible rupture of the alkyl chain and formation of new C=O and C–O–H conformations at the α-C. Infrared spectroscopy coupled with ab initio simulation can provide a powerful tool for quantifying photo-structural atomic bonding changes. As a result, understanding nanoscale light-induced structural changes will open avenues to designing more stable organic materials for organic electronics.« less

  6. Unusual infrared absorption increases in photo-degraded organic films

    DOE PAGES

    Shah, Satvik; Biswas, Rana; Koschny, Thomas; ...

    2017-06-05

    Degradation is among the most pressing problems facing organic materials, occurring through ingress of moisture and oxygen, and light exposure. We determine the nanoscale pathways underlying degradation by light-soaking organic films in an environmental chamber, and performing infrared spectroscopy, to identify atomic bonding changes. We utilize as a prototype the low band gap PTB7-PCBM blend. Films light-soaked in the presence of oxygen show unusual increased absorption at 1727 cm –1 attributable to increased C=O modes, and a broad increase at 3240 cm –1 attributable to hydroxyl (O–H) groups bonded within the organic matrix. Films exposed to oxygen in the dark,more » or light-soaked in an inert atmosphere, do not exhibit significant absorption changes, suggesting simultaneous exposure of oxygen and light that creates singlet excited oxygen is the detrimental factor. Our ab initio electronic structure simulations interpret these by oxidation at the α-C site of the alkyl chains in PTB7, with an irreversible rupture of the alkyl chain and formation of new C=O and C–O–H conformations at the α-C. Infrared spectroscopy coupled with ab initio simulation can provide a powerful tool for quantifying photo-structural atomic bonding changes. As a result, understanding nanoscale light-induced structural changes will open avenues to designing more stable organic materials for organic electronics.« less

  7. Absorption of Thermal Neutrons in Uranium

    DOE R&D Accomplishments Database

    Creutz, E. C.; Wilson, R. R.; Wigner, E. P.

    1941-09-26

    A knowledge of the absorption processes for neutrons in uranium is important for planning a chain reaction experiment. The absorption of thermal neutrons in uranium and uranium oxide has been studied. Neutrons from the cyclotron were slowed down by passage through a graphite block. A uranium or uranium oxide sphere was placed at various positions in the block. The neutron intensity at different points in the sphere and in the graphite was measured by observing the activity induced in detectors or uranium oxide or manganese. It was found that both the fission activity in the uranium oxide and the activity induced in manganese was affected by non-thermal neutrons. An experimental correction for such effects was made by making measurements with the detectors surrounded by cadmium. After such corrections the results from three methods of procedure with the uranium oxide detectors and from the manganese detectors were consistent to within a few per cent.

  8. Laser-induced photo-thermal strain imaging

    NASA Astrophysics Data System (ADS)

    Choi, Changhoon; Ahn, Joongho; Jeon, Seungwan; Kim, Chulhong

    2018-02-01

    Vulnerable plaque is the one of the leading causes of cardiovascular disease occurrence. However, conventional intravascular imaging techniques suffer from difficulty in finding vulnerable plaque due to limitation such as lack of physiological information, imaging depth, and depth sensitivity. Therefore, new techniques are needed to help determine the vulnerability of plaque, Thermal strain imaging (TSI) is an imaging technique based on ultrasound (US) wave propagation speed that varies with temperature of medium. During temperature increase, strain occurs in the medium and its variation tendency is depending on the type of tissue, which makes it possible to use for tissue differentiation. Here, we demonstrate laser-induced photo-thermal strain imaging (pTSI) to differentiate tissue using an intravascular ultrasound (IVUS) catheter and a 1210-nm continuous-wave laser for heating lipids intensively. During heating, consecutive US images were obtained from a custom-made phantom made of porcine fat and gelatin. A cross correlation-based speckle-tracking algorithm was then applied to calculate the strain of US images. In the strain images, the positive strain produced in lipids (porcine fat) was clearly differentiated from water-bearing tissue (gelatin). This result shows that laser-induced pTSI could be a new method to distinguish lipids in the plaque and can help to differentiate vulnerability of plaque.

  9. Surface Chemistry Manipulation of Gold Nanorods Displays High Cellular Uptake In Vitro While Preserving Optical Properties for Bio-Imaging and Photo-Thermal Applications

    DTIC Science & Technology

    2016-03-28

    PROPERTIES FOR BIO -IMAGING AND PHOTO-THERMAL APPLICATIONS ANTHONY B. POLITO III, Maj, USAF, BSC, PhD, MT(ASCP)SBB March 2016 Final Report for March...HIGH CELLULAR UPTAKE IN VITRO WHILE PRESERVING OPTICAL PROPERTIES FOR BIO -IMAGING AND PHOTO-THERMAL APPLICATIONS. 5a. CONTRACT NUMBER 5b...These findings identify MTAB-TA GNRs as prime candidates for use in nano-based bio -imaging and photo-thermal applications. 15. SUBJECT TERMS

  10. UV-vis spectroscopic studies of CaF2 photo-thermo-refractive glass

    NASA Astrophysics Data System (ADS)

    Stoica, Martina; Herrmann, Andreas; Hein, Joachim; Rüssel, Christian

    2016-12-01

    A photo-thermo-refractive glass based on the system Na2O/K2O/CaO/CaF2/Al2O3/ZnO/SiO2 doped with Ag2O, CeO2, SnO2, Sb2O3 and KBr was investigated. This glass undergoes a permanent refractive index change after UV irradiation and subsequent two step heat treatment at temperatures above Tg. This is due to the formation of Ag metal clusters which act as nucleation centers for CaF2 crystallization. Oxidation of Ce3+ by UV light is the initial reaction and acts as photosensitizer in the glass. The UV-vis absorption spectra during this photo-induced crystallization process were measured. The spectral components that form the absorption spectra of cerium were studied in detail by a band separation with Gaussian functions. Deconvolution of the cerium absorption bands shows an envelope of five spectral components for the trivalent cerium due to the 4f-5d transitions and two spectral components for the tetravalent cerium caused by charge transfer transitions. The effect of different dopants and melting conditions on the photo-thermal process were studied to investigate the influence of glass technology on the photoprocess.

  11. Coherent Generation of Photo-Thermo-Acoustic Wave from Graphene Sheets

    NASA Astrophysics Data System (ADS)

    Tian, Yichao; Tian, He; Wu, Yanling; Zhu, Leilei; Tao, Luqi; Zhang, Wei; Shu, Yi; Xie, Dan; Yang, Yi; Wei, Zhiyi; Lu, Xinghua; Ren, Tian-Ling; Shih, Chih-Kang; Zhao, Jimin

    Many remarkable properties of graphene are derived from its large energy window for Dirac-like electronic states and have been explored for applications in electronics and photonics. In addition, strong electron-phonon interaction in graphene has led to efficient photo-thermo energy conversions, which has been harnessed for energy applications. By combining the wavelength independent absorption property and the efficient photo-thermo energy conversion, here we report a new type of applications in sound wave generation underlined by a photo-thermo-acoustic energy conversion mechanism. Most significantly, by utilizing ultrafast optical pulses, we demonstrate the ability to control the phase of sound waves generated by the photo-thermal-acoustic process. Our finding paves the way for new types of applications for graphene, such as remote non-contact speakers, optical-switching acoustic devices, etc. National Basic Research Program of China MOST (2012CB821402), External Cooperation Program of Chinese Academy of Sciences (GJHZ1403), and National Natural Science Foundation of China (11274372).

  12. Near Infrared Fluorescence Imaging in Nano-Therapeutics and Photo-Thermal Evaluation

    PubMed Central

    Vats, Mukti; Mishra, Sumit Kumar; Baghini, Mahdieh Shojaei; Chauhan, Deepak S.; Srivastava, Rohit; De, Abhijit

    2017-01-01

    The unresolved and paramount challenge in bio-imaging and targeted therapy is to clearly define and demarcate the physical margins of tumor tissue. The ability to outline the healthy vital tissues to be carefully navigated with transection while an intraoperative surgery procedure is performed sets up a necessary and under-researched goal. To achieve the aforementioned objectives, there is a need to optimize design considerations in order to not only obtain an effective imaging agent but to also achieve attributes like favorable water solubility, biocompatibility, high molecular brightness, and a tissue specific targeting approach. The emergence of near infra-red fluorescence (NIRF) light for tissue scale imaging owes to the provision of highly specific images of the target organ. The special characteristics of near infra-red window such as minimal auto-fluorescence, low light scattering, and absorption of biomolecules in tissue converge to form an attractive modality for cancer imaging. Imparting molecular fluorescence as an exogenous contrast agent is the most beneficial attribute of NIRF light as a clinical imaging technology. Additionally, many such agents also display therapeutic potentials as photo-thermal agents, thus meeting the dual purpose of imaging and therapy. Here, we primarily discuss molecular imaging and therapeutic potentials of two such classes of materials, i.e., inorganic NIR dyes and metallic gold nanoparticle based materials. PMID:28452928

  13. Investigations of the possibility of determination of thermal parameters of Si and SiGe samples based on the Photo Thermal Radiometry technique

    NASA Astrophysics Data System (ADS)

    Chrobak, Ł.; Maliński, M.

    2018-03-01

    This paper presents results of investigations of the possibility of determination of thermal parameters (thermal conductivity, thermal diffusivity) of silicon and silicon germanium crystals from the frequency characteristics of the Photo Thermal Radiometry (PTR) signal. The theoretical analysis of the influence of the mentioned parameters on the PTR signal has been presented and discussed. The values of the thermal and recombination parameters have been extracted from the fittings of the theoretical to experimental data. The presented approach uses the reference Si sample whose thermal and recombination parameters are known.

  14. The Absorption Refrigerator as a Thermal Transformer

    ERIC Educational Resources Information Center

    Herrmann, F.

    2009-01-01

    The absorption refrigerator can be considered a thermal transformer, that is, a device that is analogous to the electric transformer. The analogy is based on the correspondence between the extensive quantities, entropy and electric charge and the intensive variables, temperature and electric potential. (Contains 1 footnote and 6 figures.)

  15. An ultra-fast optical shutter exploiting total light absorption in a phase change material

    NASA Astrophysics Data System (ADS)

    Jafari, Mohsen; Guo, L. Jay; Rais-Zadeh, Mina

    2017-02-01

    In this paper, we present an ultra-fast and high-contrast optical shutter with applications in atomic clock assemblies, integrated photonic systems, communication hardware, etc. The shutter design exploits the total light absorption phenomenon in a thin phase change (PC) material placed over a metal layer. The shutter switches between ON and OFF states by changing PC material phase and thus its refractive index. The PC material used in this work is Germanium Telluride (GeTe), a group IV-VI chalcogenide compound, which exhibits good optical contrast when switching from amorphous to crystalline state and vice versa. The stable phase changing behavior and reliability of GeTe and GeSbTe (GST) have been verified in optical memories and RF switches. Here, GeTe is used as it has a lower extinction coefficient in near-IR regions compared to GST. GeTe can be thermally transitioned between two phases by applying electrical pulses to an integrated heater. The memory behavior of GeTe results in zero static power consumption which is useful in applications requiring long time periods between switching activities. We previously demonstrated a meta-surface employing GeTe in sub-wavelength slits with >14 dB isolation at 1.5 μm by exciting the surface plasmon polariton and localized slit resonances. In this work, strong interference effects in a thin layer of GeTe over a gold mirror result in near total light absorption of up to 40 dB (21 dB measured) in the amorphous phase of the shutter at 780 nm with much less fabrication complexity. The optical loss at the shutter ON state is less than 1.5 dB. A nickel chrome (NiCr) heater provides the Joule heating energy required to achieve the crystallographic phase change. The measured switching speed is 2 μs.

  16. Photodetector based on Vernier-Enhanced Fabry-Perot Interferometers with a Photo-Thermal Coating

    PubMed Central

    Chen, George Y.; Wu, Xuan; Liu, Xiaokong; Lancaster, David G.; Monro, Tanya M.; Xu, Haolan

    2017-01-01

    We present a new type of fiber-coupled photodetector with a thermal-based optical sensor head, which enables it to operate even in the presence of strong electro-magnetic interference and in electrically sensitive environments. The optical sensor head consists of three cascaded Fabry-Perot interferometers. The end-face surface is coated with copper-oxide micro-particles embedded in hydrogel, which is a new photo-thermal coating that can be readily coated on many different surfaces. Under irradiation, photons are absorbed by the photo-thermal coating, and are converted into heat, changing the optical path length of the probing light and induces a resonant wavelength shift. For white-light irradiation, the photodetector exhibits a power sensitivity of 760 pm/mW, a power detection limit of 16.4 μW (i.e. specific detectivity of 2.2 × 105 cm.√Hz/W), and an optical damage threshold of ~100 mW or ~800 mW/cm2. The response and recovery times are 3.0 s (~90% of change within 100 ms) and 16.0 s respectively. PMID:28139745

  17. Phase lag deduced information in photo-thermal actuation for nano-mechanical systems characterization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bijster, R. J. F., E-mail: roy.bijster@tno.nl; Vreugd, J. de; Sadeghian, H.

    2014-08-18

    In photo-thermal actuation, heat is added locally to a micro-cantilever by means of a laser. A fraction of the irradiation is absorbed, yielding thermal stresses and deformations in the structure. Harmonic modulation of the laser power causes the cantilever to oscillate. Moreover, a phase lag is introduced which is very sensitive to the spot location and the cantilever properties. This phase lag is theoretically predicted and experimentally verified. Combined with thermo-mechanical properties of the cantilever and its geometry, the location of the laser spot, the thermal diffusivity, and the layer thicknesses of the cantilever can be extracted.

  18. Directional Thermal Emission and Absorption from Surface Microstructures in Metalized Plastics

    DTIC Science & Technology

    2013-09-01

    conductive surfaces for directional emission is presented. First, key accomplishments in exploiting surface plasmons for coherent thermal emission from...than as an absorbing coating . In the 2005 design proposed by Lee et al., thermally excited surface waves at a silicon carbide to photonic crystal stack...sufficiently to significantly effect the film durability and thermal conductivity , the profile of the cavity begins to change shape. Although a case

  19. Photo-irradiation paradigm: Mapping a remarkable facile technique used for advanced drug, gene and cell delivery.

    PubMed

    Shaker, Mohamed A; Younes, Husam M

    2015-11-10

    Undoubtedly, the progression of photo-irradiation technique has provided a smart engineering tool for the state-of-the-art biomaterials that guide the biomedical and therapeutic domains for promoting the modern pharmaceutical industry. Many investigators had exploited such a potential technique to create/ameliorate numerous pharmaceutical carriers. These carriers show promising applications that vary from small drug to therapeutic protein delivery and from gene to living cell encapsulation design. Harmony between the properties of precisely engineered precursors and the formed network structure broadens the investigator's intellect for both brilliant creations and effective applications. As well, controlling photo-curing at the formulation level, through manipulating the absorption of light stimuli, photoinitiator system and photo-responsive precursor, facilitates the exploration of novel distinctive biomaterials. Discussion of utilizing different photo-curing procedures in designing/formulation of different pharmaceutical carriers is the main emphasis of this review. In addition, recent applications of these intelligent techniques in targeted, controlled, and sustained drug delivery with understanding of photo-irradiation concept and mechanism are illustrated. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Cryogenic Thermal Absorptance Measurements on Small-Diameter Stainless Steel Tubing

    NASA Technical Reports Server (NTRS)

    Tuttle, James; Jahromi, Amir; Canavan, Edgar; DiPirro, Michael

    2015-01-01

    The Mid Infrared Instrument (MIRI) on the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 Kelvin operating temperature. The coolant gas flows through several meters of small-diameter stainless steel tubing, which is exposed to thermal radiation from its environment. Over much of its length this tubing is gold-plated to minimize the absorption of this radiant heat. In order to confirm that the cryocooler will meet MIRI's requirements, the thermal absorptance of this tubing was measured as a function of its environment temperature. We describe the measurement technique and present the results.

  1. Enhanced Radiotherapy using Bismuth Sulfide Nanoagents Combined with Photo-thermal Treatment.

    PubMed

    Cheng, Xiaju; Yong, Yuan; Dai, Yiheng; Song, Xin; Yang, Gang; Pan, Yue; Ge, Cuicui

    2017-01-01

    Nanotechniques that can improve the effectiveness of radiotherapy (RT) by integrating it with multimodal imaging are highly desirable. Results In this study, we fabricated Bi 2 S 3 nanorods that have attractive features such as their ability to function as contrast agents for X-ray computed tomography (CT) and photoacoustic (PA) imaging as well as good biocompatibility. Both in vitro and in vivo studies confirmed that the Bi 2 S 3 nanoagents could potentiate the lethal effects of radiation via amplifying the local radiation dose and enhancing the anti-tumor efficacy of RT by augmenting the photo-thermal effect. Furthermore, the nanoagent-mediated hyperthermia could effectively increase the oxygen concentration in hypoxic regions thereby inhibiting the expression of hypoxia-inducible factor ( HIF -1α). This, in turn, interfered with DNA repair via decreasing the expression of DNA repair-related proteins to overcome radio-resistance. Also, RT combined with nanoagent-mediated hyperthermia could substantially suppress tumor metastasis via down-regulating angiogenic factors. Conclusion In summary, we constructed a single-component powerful nanoagent for CT/PA imaging-guided tumor radiotherapy and, most importantly, explored the potential mechanisms of nanoagent-mediated photo-thermal treatment for enhancing the efficacy of RT in a synergistic manner.

  2. Analysis of the hologram recording on the novel chloride photo-thermo-refractive glass

    NASA Astrophysics Data System (ADS)

    Ivanov, S. A.; Nikonorov, N. V.; Dubrovin, V. D.; Krykova, V. A.

    2017-05-01

    In this research, we present new holographic material based on fluoride photo-thermo-refractive glass(PTR) - chloride PTR glass. One of the benefit of this type of PTR glass is positive refractive index change. During this work, for the first-time volume Bragg gratings were recorded in this kind of material. The first experiments revealed that such gratings are mixed i.e. possess both absorption and phase components. Complex analysis shows that both refractive index and absorption coefficient are modulated inside the grating structure. We found out that at first there is no strict dependence of the refractive index change from dosage, but as we continue the process of thermal treatment - dependence is appear. Exposure influence on the refractive index change for this glass differs from fluoride one and shows some sort of saturation after the exposure of 4-6 J/cm2 . We distinguished refractive index change and absorption coefficient change and observed both behavior with increasing thermal treatment time. We found out that the increase of thermal treatment time results in the significant refractive index change. At the same time the absorption does `not practically change. It was found that maximum modulation of refractive index is comparable with fluoride PTR glass and achieves value of 1600 ppm. The modulation of absorption is equal to induced absorption caused by silver nanoparticles and depends from reading wavelength. Our study shows that almost all absorption is modulated inside the grating.

  3. Thin film absorption characterization by focus error thermal lensing

    NASA Astrophysics Data System (ADS)

    Domené, Esteban A.; Schiltz, Drew; Patel, Dinesh; Day, Travis; Jankowska, E.; Martínez, Oscar E.; Rocca, Jorge J.; Menoni, Carmen S.

    2017-12-01

    A simple, highly sensitive technique for measuring absorbed power in thin film dielectrics based on thermal lensing is demonstrated. Absorption of an amplitude modulated or pulsed incident pump beam by a thin film acts as a heat source that induces thermal lensing in the substrate. A second continuous wave collimated probe beam defocuses after passing through the sample. Determination of absorption is achieved by quantifying the change of the probe beam profile at the focal plane using a four-quadrant detector and cylindrical lenses to generate a focus error signal. This signal is inherently insensitive to deflection, which removes noise contribution from point beam stability. A linear dependence of the focus error signal on the absorbed power is shown for a dynamic range of over 105. This technique was used to measure absorption loss in dielectric thin films deposited on fused silica substrates. In pulsed configuration, a single shot sensitivity of about 20 ppm is demonstrated, providing a unique technique for the characterization of moving targets as found in thin film growth instrumentation.

  4. Sub-100 nm Gold Nanomatryoshkas Improve Photo-thermal Therapy Efficacy in Large and Highly Aggressive Triple Negative Breast Tumors

    PubMed Central

    Bishnoi, Sandra; Urban, Alexander; Charron, Heather; Mitchell, Tamika; Shea, Martin; Nanda, Sarmistha; Schiff, Rachel; Halas, Naomi; Joshi, Amit

    2014-01-01

    There is an unmet need for efficient near-infrared photothermal transducers for the treatment of highly aggressive cancers and large tumors where the penetration of light can be substantially reduced, and the intra-tumoral nanoparticle transport is restricted due to the presence of hypoxic or nectrotic regions. We report the performance advantages obtained by sub 100 nm gold nanomatryushkas, comprising of concentric gold-silica-gold layers compared to conventional ~150 nm silica core gold nanoshells for photothermal therapy of triple negative breast cancer. We demonstrate that a 33% reduction in silica-core-gold-shell nanoparticle size, while retaining near-infrared plasmon resonance, and keeping the nanoparticle surface charge constant, results in a four to five fold tumor accumulation of nanoparticles following equal dose of injected gold for both sizes. The survival time of mice bearing large (>1000 mm3) and highly aggressive triple negative breast tumors is doubled for the nanomatryushka treatment group under identical photo-thermal therapy conditions. The higher absorption cross-section of a nanomatryoshka results in a higher efficiency of photonic to thermal energy conversion and coupled with 4-5X accumulation within large tumors results in superior therapy efficacy. PMID:25051221

  5. Photo-response behavior of organic transistors based on thermally annealed semiconducting diketopyrrolopyrrole core

    NASA Astrophysics Data System (ADS)

    Tarsoly, Gergely; Pyo, Seungmoon

    2018-06-01

    We report the opto-electrical response of organic field-effect transistors based on a thin-film of a semiconducting diketopyrrolopyrrole (DPP) core, a popular building block for molecular semiconductors, and a polymeric gate dielectric. The thin-film of the DPP core was thermally annealed at different temperatures under N2 atmosphere to investigate the relationship between the annealing temperature and the electrical properties of the device. The results showed that the annealing process induces morphological changes in the thin film, and properly controlling the thermal annealing conditions can enhance the device performance. In addition, we also investigated in detail the photo-response behaviors by analyzing the responsivity (R) of the device with the optimally annealed DPP-core thin film under two light illumination conditions by considering the irradiance absorbed by the thin film instead of the total irradiance of the light source. We found that the proposed model could lead to a light-source-independent description of the photo-response behavior of the device, and which can be used for other applications.

  6. Impedance Matched Absorptive Thermal Blocking Filters

    NASA Technical Reports Server (NTRS)

    Wollack, E. J.; Chuss, D. T.; U-Yen, K.; Rostem, K.

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50 Omega and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  7. Impedance Matched Absorptive Thermal Blocking Filters

    NASA Technical Reports Server (NTRS)

    Wollack, E. J.; Chuss, D. T.; Rostem, K.; U-Yen, K.

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50O and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  8. Thermal emission and absorption of radiation in finite inverted-opal photonic crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Florescu, Marian; Stimpson, Andrew J.; Lee, Hwang

    We study theoretically the optical properties of a finite inverted-opal photonic crystal. The light-matter interaction is strongly affected by the presence of the three-dimensional photonic crystal and the alterations of the light emission and absorption processes can be used to suppress or enhance the thermal emissivity and absorptivity of the dielectric structure. We investigate the influence of the absorption present in the system on the relevant band edge frequencies that control the optical response of the photonic crystal. Our study reveals that the absorption processes cause spectral broadening and shifting of the band edge optical resonances, and determine a strongmore » reduction of the photonic band gap spectral range. Using the angular and spectral dependence of the band edge frequencies for stop bands along different directions, we argue that by matching the blackbody emission spectrum peak with a prescribed maximum of the absorption coefficient, it is possible to achieve an angle-sensitive enhancement of the thermal emission/absorption of radiation. This result opens a way to realize a frequency-sensitive and angle-sensitive photonic crystal absorbers/emitters.« less

  9. Quantitative absorption data from thermally induced wavefront distortions on UV, Vis, and NIR optics

    NASA Astrophysics Data System (ADS)

    Mann, Klaus; Schäfer, Bernd; Leinhos, Uwe; Lübbecke, Maik

    2017-11-01

    A photothermal absorption measurement system was set up, deploying a Hartmann-Shack wavefront sensor with extreme sensitivity to accomplish spatially resolved monitoring of thermally induced wavefront distortions. Photothermal absorption measurements in the near-infrared and deep ultra-violet spectral range are performed for the characterization of optical materials, utilizing a Yb fiber laser (λ = 1070 nm) and an excimer laser (193nm, 248nm) to induce thermal load. Wavefront deformations as low as 50pm (rms) can be registered, allowing for a rapid assessment of material quality. Absolute calibration of the absorption data is achieved by comparison with a thermal calculation. The method accomplishes not only to measure absorptances of plane optical elements, but also wavefront deformations and focal shifts in lenses as well as in complex optical systems, such as e.g. F-Theta objectives used in industrial high power laser applications. Along with a description of the technique we present results from absorption measurements on coated and uncoated optics at various laser wavelengths ranging from deep UV to near IR.

  10. Measurements of Photo-induced Changes in Conjugated Polymers

    DOE R&D Accomplishments Database

    Seager, C. H.; Sinclair, M. B.; Mc Branch, D.; Heeger, A. J.; Baker, G. L.

    1991-01-01

    We have used the highly sensitive technique of Photothermal Deflection Spectroscopy (PDS) to measure changes in the infrared absorption spectra of MEHPPV, P3HT and Polydiacetylene-4BCMU induced by pumping these polymers with light above the {pi} - {pi}* transition energy. In contrast to previous chopped light transmission measurements of these effects, the PDS technique can directly measure the buildup or decay of the absorption coefficient, {alpha}, on the time scale of second to days. In the case of MEHPPV we observe that the time scale of seconds to days. In the case of MEHPPV we observe that above-gap light causes the appearance of a broad infrared peak in {alpha}, which continues to grow-in hours after the pump light is first applied. For this polymer the general shape of the absorption spectra in the unpumped state mimics the photo-induced changes, suggesting that remnant photo-induced states determine the maximum transparency observed under normal experimental conditions. For P3HT and to a lesser extent, MEHPPV, we also observe irreversible photo-induced absorption components which we tentatively identify with photo-induced oxidation of the polymer matrix.

  11. Evidence for percutaneous absorption of isotretinoin from the photo-isomerization of topical tretinoin.

    PubMed

    Lehman, P A; Malany, A M

    1989-11-01

    Tretinoin (0.1% Retin-A cream) was topically applied to human cadaver skin in vitro using Franz diffusion chambers. The photo-isomerization of tretinoin and retinoic acid percutaneous absorption in the absence of metabolic activity were assessed with and without ambient light exposure to the skin. Using HPLC, UV, and GC/MSD, a retinoid exhibiting identical chromatographic and spectral characteristics of isotretinoin was observed in the samples from the skin exposed to light, but was virtually absent in the skin samples maintained in the dark. From a single topical application of tretinoin, isotretinoin was as abundant as tretinoin in the chamber receiver solution, dermis, epidermis, and on the skin surface at 24 h after topical application. The data suggest the possibility that isotretinoin may have an important role in the pharmacology of topically applied tretinoin.

  12. Perceptually Guided Photo Retargeting.

    PubMed

    Xia, Yingjie; Zhang, Luming; Hong, Richang; Nie, Liqiang; Yan, Yan; Shao, Ling

    2016-04-22

    We propose perceptually guided photo retargeting, which shrinks a photo by simulating a human's process of sequentially perceiving visually/semantically important regions in a photo. In particular, we first project the local features (graphlets in this paper) onto a semantic space, wherein visual cues such as global spatial layout and rough geometric context are exploited. Thereafter, a sparsity-constrained learning algorithm is derived to select semantically representative graphlets of a photo, and the selecting process can be interpreted by a path which simulates how a human actively perceives semantics in a photo. Furthermore, we learn the prior distribution of such active graphlet paths (AGPs) from training photos that are marked as esthetically pleasing by multiple users. The learned priors enforce the corresponding AGP of a retargeted photo to be maximally similar to those from the training photos. On top of the retargeting model, we further design an online learning scheme to incrementally update the model with new photos that are esthetically pleasing. The online update module makes the algorithm less dependent on the number and contents of the initial training data. Experimental results show that: 1) the proposed AGP is over 90% consistent with human gaze shifting path, as verified by the eye-tracking data, and 2) the retargeting algorithm outperforms its competitors significantly, as AGP is more indicative of photo esthetics than conventional saliency maps.

  13. A novel modeling and simulation technique of photo--thermal interactions between lasers and living biological tissues undergoing multiple changes in phase.

    PubMed

    Dua, Rajan; Chakraborty, Suman

    2005-06-01

    Knowledge of heat transfer in biological bodies has many therapeutic applications involving either raising or lowering of temperature, and often requires precise monitoring of the spatial distribution of thermal histories that are produced during a treatment protocol. Extremes of temperature into the freezing and burning ranges are useful in surgical procedures for selective killing and/or removal of target tissues. For example, the primary objective of hyperthermia is to raise the temperature of the diseased tissue to a therapeutic value, typically 41- 44 degrees C, and then thermally destroy it. The present paper therefore aims to develop a mathematical model for effective simulation of photo--thermal interactions between laser rays and biological tissues. In particular, damage of biological tissues when subjected to single point laser diathermy is numerically investigated using a unique enthalpy-based approach for modeling multiple phase change, (namely, melting of fat and vaporization of water content of the tissues) and the associated release/absorption of latent heat in conjunction with unsteady state heat conduction mechanisms. The governing equations of bio-heat transfer coupled with initial and boundary conditions are solved using a finite volume approach in conjunction with line by a line tri-diagonal matrix algorithm (TDMA) solver. Temperature responses of tissues subject to laser heating are quantitatively investigated in detail using the present model, and the resultant solutions are expected to be immensely useful in a variety of Bio-thermal practices in medicine and surgery.

  14. Pd-MnO2 nanoparticles/TiO2 nanotube arrays (NTAs) photo-electrodes photo-catalytic properties and their ability of degrading Rhodamine B under visible light.

    PubMed

    Thabit, Mohamed; Liu, Huiling; Zhang, Jian; Wang, Bing

    2017-10-01

    Pd-MnO 2 /TiO 2 nanotube arrays (NTAs) photo-electrodes were successfully fabricated via anodization and electro deposition subsequently; the obtained Pd-MnO 2 /TiO 2 NTAs photo electrodes were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and characterized accordingly. Moreover, the light harvesting and absorption properties were investigated via ultraviolet-visible diffuse reflectance spectrum (DRS); photo degradation efficiency was investigated via analyzing the photo catalytic degradation of Rhodamine B under visible illumination (xenon light). The performed analyses illustrated that Pd-MnO 2 codoped particles were successfully deposited onto the surface of the TiO 2 nanotube arrays; DRS results showed significant improvement in visible light absorption which was between 400 and 700nm. Finally, the photo catalytic degradation efficiency results of the designated organic pollutant (Rhodamine B) illustrated a superior photocatalytic (PC) efficiency of approximately 95% compared to the bare TiO 2 NTAs, which only exhibited a photo catalytic degradation efficiency of approximately 61%, thus it indicated the significant enhancement of the light absorption properties of fabricated photo electrodes and their yield of OH radicals. Copyright © 2017. Published by Elsevier B.V.

  15. Ultrafast photo-initiated molecular quantum dynamics in the DNA dinucleotide d(ApG) revealed by broadband transient absorption spectroscopy.

    PubMed

    Stuhldreier, Mayra C; Temps, Friedrich

    2013-01-01

    The ultrafast photo-initiated quantum dynamics of the adenine-guanine dinucleotide d(ApG) in aqueous solution (pH 7) has been studied by femtosecond time-resolved spectroscopy after excitation at lambda = 260 nm. The results reveal a hierarchy of processes on time scales from tau < 100 fs to tau > 100 ps. Characteristic spectro-temporal signatures are observed indicating the transformation of the molecules in the electronic relaxation from the photo-excited state to a long-lived exciplex. In particular, broadband UV/VIS excited-state absorption (ESA) measurements detected a distinctive absorption by the excited dinucleotide around lambda = 335 nm, approximately 0.5 eV to the blue compared to the maximum of the broad and unstructured ESA spectrum after excitation of an equimolar mixture of the mononucleotides dAMP and dGMP. A similar feature has been identified as signature of the excimer in the dynamics of the adenine dinucleotide d(ApA). The lifetime of the d(ApG) exciplex was found to be tau = 124 +/- 4 ps both from the ESA decay time and from the ground-state recovery time, far longer than the sub-picosecond lifetimes of excited dAMP or dGMP. Fluorescence-time profiles measured by the up-conversion technique indicate that the exciplex state is reached around approximately 6 ps after excitation. Very weak residual fluorescence at longer times red-shifted to the emission from the photo-excited state shows that the exciplex is almost optically dark, but still has enough oscillator strength to give rise to the dual fluorescence of the dinucleotide in the static fluorescence spectrum.

  16. Absorption and emission spectroscopic characterization of photo-dynamics of photoactivated adenylyl cyclase mutant bPAC-Y7F of Beggiatoa sp.

    PubMed

    Penzkofer, Alfons; Stierl, Manuela; Mathes, Tilo; Hegemann, Peter

    2014-11-01

    The photoactivated cyclase bPAC of the microbial mats bacterium Beggiatoa sp. consists of a BLUF domain and an adenylyl cyclase domain. It has strong activity of photo-induced cyclic adenylyl monophosphate (cAMP) formation and is therefore an important optogenetic tool in neuroscience applications. The SUMO-bPAC-Y7F mutant where Tyr-7 is replaced by Phe-7 in the BLUF domain has lost the typical BLUF domain photo-cycle dynamics. Instead, the investigated SUMO-bPAC-Y7F mutant consisted of three protein conformations with different triplet based photo-dynamics: (i) reversible flavin quinone (Fl) cofactor reduction to flavin semiquinone (FlH), (ii) reversible violet/near ultraviolet absorbing flavin photoproduct (FlA) formation, and (iii) irreversible red absorbing flavin photoproduct (FlC) formation. Absorption and emission spectroscopic measurements on SUMO-bPAC-Y7F were carried out before, during and after light exposure. Flavin photo-dynamics schemes are developed for the SUMO-bPAC-Y7F fractions performing photo-induced FlH, FlA, and FlC formation. Quantitative parameters of the flavin cofactor excitation, relaxation and recovery dynamics in SUMO-bPAC-Y7F are determined. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Gigahertz-peaked Spectra Pulsars and Thermal Absorption Model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kijak, J.; Basu, R.; Lewandowski, W.

    2017-05-10

    We present the results of our radio interferometric observations of pulsars at 325 and 610 MHz using the Giant Metrewave Radio Telescope. We used the imaging method to estimate the flux densities of several pulsars at these radio frequencies. The analysis of the shapes of the pulsar spectra allowed us to identify five new gigahertz-peaked spectra (GPS) pulsars. Using the hypothesis that the spectral turnovers are caused by thermal free–free absorption in the interstellar medium, we modeled the spectra of all known objects of this kind. Using the model, we were able to put some observational constraints on the physicalmore » parameters of the absorbing matter, which allows us to distinguish between the possible sources of absorption. We also discuss the possible effects of the existence of GPS pulsars on future search surveys, showing that the optimal frequency range for finding such objects would be from a few GHz (for regular GPS sources) to possibly 10 GHz for pulsars and radio magnetars exhibiting very strong absorption.« less

  18. A giant enhancement of multiphoton absorption in single-layer molybdenum disulfide

    NASA Astrophysics Data System (ADS)

    Zhou, Feng; Ji, Wei

    Identifying light absorption mechanisms in nanoscale materials, which are more efficient than those observed in bulk semiconductors, are of paramount importance to next-generation, infrared photo-detection. Here, we report considerable enhancement of degenerate two-photon absorption (2PA) and three-photon absorption (3PA) through two-dimensional (2D) excitonic effects in single-layer molybdenum disulfide (1L-MoS2) . We theoretically predict that both degenerate 2PA and 3PA coefficients of 1L-MoS2 are enhanced by 10-1000 times in the near-infrared (NIR), as compared with those of bulk semiconductors. Our theoretical prediction is validated by measuring photocurrents induced by 2PA or 3PA in a 1L-MoS2 photo-detector at room temperature where excitons in the immediate vicinity of the bandgap are transferred to the conduction band by a very small amount of thermal energy and dissociated under an external electric field. Our finding lays theoretical foundation and provides experimental evidence for developing sensitive infrared multiphoton detectors for nano-photonics. This work was supported by National University of Singapore through a research Grant: R144-000-327-112.

  19. Frequency and Thermal Behavior of Acoustic Absorption in ɛ-GaSe Crystals

    NASA Astrophysics Data System (ADS)

    Dzhafarova, S. Z.

    2018-04-01

    The paper presents results of measuring acoustic absorption in ɛ-GaSe crystals. The absorption of a longitudinal wave which propagates normal to the crystal layers, quadratically depends on frequency. However, it does not depend on temperature, i.e. it displays an Akhiezer behavior although its absolute value considerably exceeds the expected. The analysis of the frequency and thermal behavior of absorption of piezoelectric waves propagating along the layers, includes the deduction of contribution made by the interaction between waves and charge carriers. This analysis shows the linear dependence between the lattice absorption of these waves and the frequency. The linear frequency and weak temperature dependences of the acoustic absorption characterize the additional ultra-Akhiezer absorption in glasses. In our case, it can be caused by various polytypes forming in GaSe crystals which differ merely in a mutual arrangement of layers.

  20. Modelling the competition between photo-darkening and photo-bleaching effects in high-power ytterbium-doped fibre amplifiers

    NASA Astrophysics Data System (ADS)

    Jolly, A.; Vinçont, C.; Pierre, Ch.; Boullet, J.

    2017-08-01

    We propose an innovative, fully space-time model to take into account the seed-dependent nature of ageing penalties in high-power ytterbium-doped fibre amplifiers. Ageing is shown to be based on the on-going competition between photo-darkening and photo-bleaching phenomena. Our approach is based on the natural interplay between the excited states of co-existing ytterbium pairs and colour centres in highly doped fibres, in the presence of thermal coupling between the closely spaced excited states. As initiated from IR photons, the excitation of colour centres up to the UV band is supposed to be governed by multi-photon absorption. The interactions of interest in the kinetics of photo-bleaching then take the form of highly efficient charge transfers, which imply the reduction of some fraction of the basically trivalent ions to their divalent state. Due to the activation of ytterbium pairs by means of energy transfer up-conversion, these interactions get more and more effective at elevated operating powers. Computational results using these principles actually help to fit our experimental data regarding seeding effects, as well as fully generic trends already evidenced in the literature. This gives a fine demonstration for the need to discriminate co-active pump and signal contributions. Our self-consistent, still simplified model then consists of a valuable tool to help for a deeper understanding of the ageing issues. Furthermore, considering higher-order ytterbium aggregates, this should open new routes towards more comprehensive models.

  1. Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion.

    PubMed

    Thomas, Nathan H; Chen, Zhen; Fan, Shanhui; Minnich, Austin J

    2017-07-13

    Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In field tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. With straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat.

  2. Photo-thermal characteristics of hybrid nanofluids based on Therminol-55 oil for concentrating solar collectors

    NASA Astrophysics Data System (ADS)

    Gulzar, Ovais; Qayoum, Adnan; Gupta, Rajat

    2018-03-01

    Hybrid nanofluids are the new generation efficient heat transfer fluids allowing greater control over the properties of base fluid as compared to mono-nanofluids. In this study, attempt has been made for increasing the efficiency for photo-thermal conversion by heat transfer fluid for high temperature solar collectors. Therminol-55, a high temperature heat transfer fluid is doped with Al2O3 and TiO2 nanoparticles with an aim to improve the thermal and optical properties. Effects of concentration and type of nanoparticle on photo-thermal conversion properties and absorbance in Therminol-55 have been studied. Spectrophotometric analysis has been carried for all nanofluids, namely, Al2O3-Therminol-55, TiO2-Therminol-55 and hybrid (Al2O3-TiO2)-Therminol-55 nanofluids with varying concentrations of 0.05, 0.075, 0.1, 0.25, 0.5 wt%. It was found that TiO2 nanofluids possess the maximum absorbance with minimal effect of nanoparticle concentration above 0.1 wt% followed by hybrid (Al2O3-TiO2) nanofluid (HNF) with strong dependence of concentration. Al2O3-Therminol-55 nanofluids exhibited least absorbance. The peak values of absorbance are 0.47, 2.15 and 2.144 in the visible region for Al2O3-Therminol-55, TiO2-Therminol-55 and hybrid (Al2O3-TiO2)-Therminol-55 nanofluids, respectively. It was observed that hybrid nanofluids show both bathochromic and hyperchromic shifts. Further, performance testing has been carried out using artificial source of light and it has been observed that hybrid nanofluids provide efficient photo-thermal conversion as compared to TiO2 and Al2O3-Therminol-55 nanofluids. Maximum temperatures of 152.9, 149.6, 158.6 °C were observed for 0.5 wt% Al2O3-Therminol-55, 0.1 wt% TiO2-Therminol-55, and 0.5 wt% hybrid (Al2O3-TiO2) nanofluid, respectively, against 125.8 °C of Therminol-55. Hybrid nanofluids based on Therminol-55 could be a potential candidate for high temperature concentrating collectors based on the superior properties over mono-nanofluids and

  3. Thermal stability control system of photo-elastic interferometer in the PEM-FTs

    NASA Astrophysics Data System (ADS)

    Zhang, M. J.; Jing, N.; Li, K. W.; Wang, Z. B.

    2018-01-01

    A drifting model for the resonant frequency and retardation amplitude of a photo-elastic modulator (PEM) in the photo-elastic modulated Fourier transform spectrometer (PEM-FTs) is presented. A multi-parameter broadband-matching driving control method is proposed to improve the thermal stability of the PEM interferometer. The automatically frequency-modulated technology of the driving signal based on digital phase-locked technology is used to track the PEM's changing resonant frequency. Simultaneously the maximum optical-path-difference of a laser's interferogram is measured to adjust the amplitude of the PEM's driving signal so that the spectral resolution is stable. In the experiment, the multi-parameter broadband-matching control method is applied to the driving control system of the PEM-FTs. Control of resonant frequency and retardation amplitude stabilizes the maximum optical-path-difference to approximately 236 μm and results in a spectral resolution of 42 cm-1. This corresponds to a relative error smaller than 2.16% (4.28 standard deviation). The experiment shows that the method can effectively stabilize the spectral resolution of the PEM-FTs.

  4. Dynamical thermal effects in InGaAsP microtubes at telecom wavelengths.

    PubMed

    Tian, Zhaobing; Bianucci, Pablo; Roche, Philip J R; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Poole, Philip J; Kirk, Andrew G; Plant, David V

    2012-07-01

    We report on the observation of a dynamical thermal effect in InGaAsP microtubes at telecom wavelengths. The microtubes are fabricated by releasing a strained semiconductor bilayer and are picked up by abruptly tapered optical fibers for subsequent coupling with adiabatically tapered optical fibers. As a result of absorption by InAs quantum dots embedded in the tube structure, these microtubes show dynamical thermal effects at wavelengths around 1525 nm and 1578 nm, while they are passive at longer wavelengths near 1634 nm. The photon absorption induced thermal effect is visualized by generating a pair of microbottles. The dynamical thermal effect can be avoided or exploited for passive or active applications by utilizing appropriate resonance wavelengths.

  5. Thiomersal photo-degradation with visible light mediated by graphene quantum dots: Indirect quantification using optical multipath mercury cold-vapor absorption spectrophotometry

    NASA Astrophysics Data System (ADS)

    Miranda-Andrades, Jarol R.; Khan, Sarzamin; Toloza, Carlos A. T.; Romani, Eric C.; Freire Júnior, Fernando L.; Aucelio, Ricardo Q.

    2017-12-01

    Thiomersal is employed as preservative in vaccines, cosmetic and pharmaceutical products due to its capacity to inhibit bacterial growth. Thiomersal contains 49.55% of mercury in its composition and its highly toxic ethylmercury degradation product has been linked to neurological disorders. The photo-degradation of thiomersal has been achieved by visible light using graphene quantum dots as catalysts. The generated mercury cold vapor (using adjusted experimental conditions) was detected by multipath atomic absorption spectrometry allowing the quantification of thiomersal at values as low as 20 ng L- 1 even in complex samples as aqueous effluents of pharmaceutical industry and urine. A kinetic study (pseudo-first order with k = 0.11 min- 1) and insights on the photo-degradation process are presented.

  6. Failure Investigation & Design Optimization of a Photo-Multiplier Tube Assembly Under Thermal Loading

    NASA Technical Reports Server (NTRS)

    Dahya, Kevin

    2004-01-01

    Analysis of GLAST ACD Photo-Multiplier Tube (PMT) assembly under thermal loading demonstrates that the glass tube experiences high stresses due to Coefficient of Thermal Expansion mismatch, as well as increased stress due to high stiffness and incompressibility of potting compound. Further investigation shows adverse loading effects due to the magnetic shield, a thin piece of steel wrapped around the PMT. This steel, Mu Metal, contained an overlap region that directly attributed to crack propagation in the outside surface of the tube. Sensitivities to different configurations were studied to reduce the stress and provide a more uniform loading throughout the PMT to ensure mission success. Studies indicate substituting a softer and more compressible potting compound and moving the Mu metal from the glass tube to the outside wall of the aluminum housing yields lower stress.

  7. Metal-centred azaphosphatriptycene gear with a photo- and thermally driven mechanical switching function based on coordination isomerism.

    PubMed

    Ube, Hitoshi; Yasuda, Yoshihiro; Sato, Hiroyasu; Shionoya, Mitsuhiko

    2017-02-08

    Metal ions can serve as a centre of molecular motions due to their coordination geometry, reversible bonding nature and external stimuli responsiveness. Such essential features of metal ions have been utilized for metal-mediated molecular machines with the ability to motion switch via metallation/demetallation or coordination number variation at the metal centre; however, motion switching based on the change in coordination geometry remain largely unexplored. Herein, we report a Pt II -centred molecular gear that demonstrates control of rotor engagement and disengagement based on photo- and thermally driven cis-trans isomerization at the Pt II centre. This molecular rotary motion transmitter has been constructed from two coordinating azaphosphatriptycene rotators and one Pt II ion as a stator. Isomerization between an engaged cis-form and a disengaged trans-form is reversibly driven by ultraviolet irradiation and heating. Such a photo- and thermally triggered motional interconversion between engaged/disengaged states on a metal ion would provide a selector switch for more complex interlocking systems.

  8. Abnormal photothermal effect of laser radiation on highly defect oxide bronze nanoparticles under the sub-threshold excitation of absorption

    NASA Astrophysics Data System (ADS)

    Gulyaev, P.; Kotvanova, M.; Omelchenko, A.

    2017-05-01

    The mechanism of abnormal photo-thermal effect of laser radiation on nanoparticles of oxide bronzes has been proposed in this paper. The basic features of the observed effect are: a) sub-threshold absorption of laser radiation by the excitation of donor-like levels formed in the energy gap due to superficial defects of the oxide bronze nano-crystals; b) an interband radiationless transition of energy of excitation on deep triplet levels and c) consequent recombination occurring at the plasmon absorption. K or Na atoms thermally intercalated to the octahedral crystal structure of TiO2 in the wave SHS combustion generate acceptor levels in the gap. The prepared oxide bronzes of the non-stoichiometric composition NaxTiO2 and KxTiO2 were examined by high resolution TEM, and then grinded in a planetary mill with powerful dispersion energy density up to 4000 J/g. This made it possible to obtain nanoparticles about 50 nm with high surface defect density (1017-1019 cm-2 at a depth of 10 nm). High photo-thermal effect of laser radiation on the defect nanocrystals observed after its impregnation into cartilaginous tissue exceeds 7 times in comparison with the intact ones.

  9. Photo-degradation behaviour of roseoflavin in some aqueous solutions

    NASA Astrophysics Data System (ADS)

    Tyagi, A.; Penzkofer, A.; Mathes, T.; Hegemann, P.

    2010-03-01

    An absorption and emission spectroscopic characterization of roseoflavin (8-dimethylamino-8-demethyl-riboflavin, RoF) in aqueous solutions was carried out. The studies were concentrated on roseoflavin in pH 8 phosphate buffer. Absorption cross-section spectra, fluorescence excitation spectra, fluorescence quantum distributions, fluorescence quantum yields and fluorescence lifetimes were determined. The fluorescence of RoF is quenched by photo-induced intra-molecular charge-transfer at room temperature. The photo-degradation of RoF in un-buffered water, in Tris-HCl buffer, and in phosphate buffer was studied. Phosphate buffer and to a smaller extent Tris buffer catalyse the RoF photo-degradation. Photo-excitation of the primary photoproduct, 8-methylamino-riboflavin (8-MNH-RF), enhanced the RoF degradation by triplet 8-MNH-RF - singlet RoF excitation transfer with subsequent triplet-state RoF degradation.

  10. Optimization of Norbornadiene Compounds for Solar Thermal Storage by First-Principles Calculations.

    PubMed

    Kuisma, Mikael; Lundin, Angelica; Moth-Poulsen, Kasper; Hyldgaard, Per; Erhart, Paul

    2016-07-21

    Molecular photoswitches capable of storing solar energy are interesting candidates for future renewable energy applications. Here, using quantum mechanical calculations, we carry out a systematic screening of crucial optical (solar spectrum match) and thermal (storage energy density) properties of 64 such compounds based on the norbornadiene-quadricyclane system. Whereas a substantial number of these molecules reach the theoretical maximum solar power conversion efficiency, this requires a strong red-shift of the absorption spectrum, which causes undesirable absorption by the photoisomer as well as reduced thermal stability. These compounds typically also have a large molecular mass, leading to low storage densities. By contrast, single-substituted systems achieve a good compromise between efficiency and storage density, while avoiding competing absorption by the photo-isomer. This establishes guiding principles for the future development of molecular solar thermal storage systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Photo-Induced Assembly of a Luminescent Tetraruthenium Square.

    PubMed

    Laramée-Milette, Baptiste; Nastasi, Francesco; Puntoriero, Fausto; Campagna, Sebastiano; Hanan, Garry S

    2017-11-21

    Self-assembly is a powerful synthetic tool that has led to the development of one-, two- and three-dimensional architectures. From MOFs to molecular flasks, self-assembled materials have proven to be of great interest to the scientific community. Here we describe a strategy for the construction and de-construction of a supramolecular structure through unprecedented photo-induced assembly and dis-assembly. The combination of two approaches, a [n×1]-directional bonding strategy and a ligand photo-dissociation strategy, allows the photo-induced assembly of a polypyridyl Ru II precursor into a discrete molecular square. Diffusion-ordered NMR spectroscopy confirmed the synthesis of a higher volume species, while the identity of the species was established by high-resolution mass spectrometry and single-crystal X-ray diffraction studies. The self-assembled square is not obtained by classical thermal techniques in similar conditions, but is obtained only by light-irradiation. The tetraruthenium square has an excited-state lifetime (135 ns), 40 times that of its mononuclear precursor and its luminescence quantum yield (1.0 %) is three orders of magnitude higher. These remarkable luminescence properties are closely related to the relatively rigid square structure of the tetraruthenium assembly, as suggested by slow radiationless decay and transient absorption spectroscopy. The results described herein are a rare example of photo-induced assembly and dis-assembly processes, and can open the way to a new avenue in supramolecular chemistry, leading to the preparation of structurally organized supermolecules by photochemical techniques. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Thermal Scanning of Dental Pulp Chamber by Thermocouple System and Infrared Camera during Photo Curing of Resin Composites.

    PubMed

    Hamze, Faeze; Ganjalikhan Nasab, Seyed Abdolreza; Eskandarizadeh, Ali; Shahravan, Arash; Akhavan Fard, Fatemeh; Sinaee, Neda

    2018-01-01

    Due to thermal hazard during composite restorations, this study was designed to scan the pulp temperature by thermocouple and infrared camera during photo polymerizing different composites. A mesio-occlso-distal (MOD) cavity was prepared in an extracted tooth and the K-type thermocouple was fixed in its pulp chamber. Subsequently, 1 mm increment of each composites were inserted (four composite types were incorporated) and photo polymerized employing either LED or QTH systems for 60 sec while the temperature was recorded with 10 sec intervals. Ultimately, the same tooth was hemisected bucco-lingually and the amalgam was removed. The same composite curing procedure was repeated while the thermogram was recorded using an infrared camera. Thereafter, the data was analyzed by repeated measured ANOVA followed by Tukey's HSD Post Hoc test for multiple comparisons ( α =0.05). The pulp temperature was significantly increased (repeated measures) during photo polymerization ( P =0.000) while there was no significant difference among the results recorded by thermocouple comparing to infrared camera ( P >0.05). Moreover, different composite materials and LCUs lead to similar outcomes ( P >0.05). Although various composites have significant different chemical compositions, they lead to similar pulp thermal changes. Moreover, both the infrared camera and the thermocouple would record parallel results of dental pulp temperature.

  13. A Comparison of Photo-Induced Hysteresis Between Hydrogenated Amorphous Silicon and Amorphous IGZO Thin-Film Transistors.

    PubMed

    Ha, Tae-Jun; Cho, Won-Ju; Chung, Hong-Bay; Koo, Sang-Mo

    2015-09-01

    We investigate photo-induced instability in thin-film transistors (TFTs) consisting of amorphous indium-gallium-zinc-oxide (a-IGZO) as active semiconducting layers by comparing with hydrogenated amorphous silicon (a-Si:H). An a-IGZO TFT exhibits a large hysteresis window in the illuminated measuring condition but no hysteresis window in the dark condition. On the contrary, a large hysteresis window measured in the dark condition in a-Si:H was not observed in the illuminated condition. Even though such materials possess the structure of amorphous phase, optical responses or photo instability in TFTs looks different from each other. Photo-induced hysteresis results from initially trapped charges at the interface between semiconductor and dielectric films or in the gate dielectric which possess absorption energy to interact with deep trap-states and affect the movement of Fermi energy level. In order to support our claim, we also perform CV characteristics in photo-induced hysteresis and demonstrate thermal-activated hysteresis. We believe that this work can provide important information to understand different material systems for optical engineering which includes charge transport and band transition.

  14. Exploiting Photo-induced Reactions in Polymer Blends to Create Hierarchically Ordered, Defect-free Materials

    ScienceCinema

    Balazs, Anna [University of Pittsburgh, Pittsburgh, Pennsylvania, United States

    2017-12-09

    Computer simulations reveal how photo-induced chemical reactions can be exploited to create long-range order in binary and ternary polymeric materials. The process is initiated by shining a spatially uniform light over a photosensitive AB binary blend, which undergoes both a reversible chemical reaction and phase separation. We then introduce a well-collimated, higher-intensity light source. Rastering this secondary light over the sample locally increases the reaction rate and causes formation of defect-free, spatially periodic structures. These binary structures resemble either the lamellar or hexagonal phases of microphase-separated di-block copolymers. We measure the regularity of the ordered structures as a function of the relative reaction rates for different values of the rastering speed and determine the optimal conditions for creating defect-free structures in the binary systems. We then add a non-reactive homo-polymer C, which is immiscible with both A and B. We show that this component migrates to regions that are illuminated by the secondary, higher-intensity light, allowing us to effectively write a pattern of C onto the AB film. Rastering over the ternary blend with this collimated light now leads to hierarchically ordered patterns of A, B, and C. The findings point to a facile, non-intrusive process for manufacturing high-quality polymeric devices in a low-cost, efficient manner.

  15. Active photo-thermal self-healing of shape memory polyurethanes

    NASA Astrophysics Data System (ADS)

    Kazemi-Lari, Mohammad A.; Malakooti, Mohammad H.; Sodano, Henry A.

    2017-05-01

    Structural health monitoring (SHM) has received significant interest over the past decade and has led to the development of a wide variety of sensors and signal processing techniques to determine the presence of changes or damage in a structural system. The topic has attracted significant attention due to the safety and performance enhancing benefits as well as the potential lifesaving capabilities offered by the technology. While the resulting systems are capable of sensing their surrounding structural and environmental conditions, few methods exist for using the information to autonomously react and repair or protect the system. One of the major challenges in the future implementation of SHM systems is their coupling with materials that can react to the damage to heal themselves and return to normal function. The coupling of self-healing materials with SHM has the potential to significantly prolong the lifetime of structural systems and extend the required inspection intervals. In the present study, an optical fiber based self-healing system composed of mendable polyurethanes based on the thermally reversible Diels-Alder (DA) reaction is developed. Inspired by health monitoring techniques, active photo-thermal sensing and actuation is achieved using infrared laser light passing through an optical fiber and a thermal power sensor to detect the presence of cracking in the structure. Healing is triggered as the crack propagates through the polymer and fractures the embedded optical fiber. Through a feedback loop, the detected power drop by the sensor is utilized as a signal to heat the cracked area and stimulate the shape memory effect of the polyurethane and the retro-DA reaction. The healing performance results indicate that this novel integrated system can be effectively employed to monitor the incidence of damage and actively heal a crack in the polymer.

  16. Modification of a neuronal network direction using stepwise photo-thermal etching of an agarose architecture.

    PubMed

    Suzuki, Ikurou; Sugio, Yoshihiro; Moriguchi, Hiroyuki; Jimbo, Yasuhiko; Yasuda, Kenji

    2004-07-01

    Control over spatial distribution of individual neurons and the pattern of neural network provides an important tool for studying information processing pathways during neural network formation. Moreover, the knowledge of the direction of synaptic connections between cells in each neural network can provide detailed information on the relationship between the forward and feedback signaling. We have developed a method for topographical control of the direction of synaptic connections within a living neuronal network using a new type of individual-cell-based on-chip cell-cultivation system with an agarose microchamber array (AMCA). The advantages of this system include the possibility to control positions and number of cultured cells as well as flexible control of the direction of elongation of axons through stepwise melting of narrow grooves. Such micrometer-order microchannels are obtained by photo-thermal etching of agarose where a portion of the gel is melted with a 1064-nm infrared laser beam. Using this system, we created neural network from individual Rat hippocampal cells. We were able to control elongation of individual axons during cultivation (from cells contained within the AMCA) by non-destructive stepwise photo-thermal etching. We have demonstrated the potential of our on-chip AMCA cell cultivation system for the controlled development of individual cell-based neural networks.

  17. Optical absorption and thermal stability study of Cu doped NiO nanoparticles

    NASA Astrophysics Data System (ADS)

    Varunkumar, K.; Ethiraj, Anita Sagadevan; Kechiantz, Ara

    2018-05-01

    This work reports variation of Cu doping concentration in NiO nanoparticles (NiO:Cu NPs) synthesized via chemical co-precipitation from solution by using NiCl2.6H2O as precursor, CuSO4.5H2O as dopant and NaOH as surfactant. We studied optical and thermal stability of prepared NiO:Cu NPs by UV-Vis absorbance, Diffuse Reflectance Spectroscopy (DRS), Atomic Absorption Spectroscopy (AAS), and Thermo Gravimetric/Differential Scanning Calorimetry (TGA/DSC) analyses. Optical absorption data of NiO:Cu NPs indicated strong absorption peaks shifted towards blue with respect to the peak of undoped NiO NPs due to quantum confinement effect. The bandgap estimated via Tauc plot first increased from 3.32eV (undoped NiO NPs) to 3.37 eV (8 at % of Cu in NiO NPs) and further increase of Cu doping to 10 at% reduced the bandgap to 3.35 eV. Such behavior of the bandgap clearly indicates that the size of NiO NPs first reduces with Cu doping up to 8 at % and then increases with further Cu doping to 10 at %. This behavior of reduction in particle size with increased doping can be attributed to the dislocation density and microstrain developed in NiO:Cu NPs. Thermal stability analysis demonstrated that in addition undoped NiO NPs, all NiO:Cu nanoparticle samples exhibited good thermal stability.

  18. Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thomas, Nathan H.; Chen, Zhen; Fan, Shanhui

    Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we then report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In fieldmore » tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. Furthemore, with straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat« less

  19. Semiconductor-based Multilayer Selective Solar Absorber for Unconcentrated Solar Thermal Energy Conversion

    DOE PAGES

    Thomas, Nathan H.; Chen, Zhen; Fan, Shanhui; ...

    2017-07-13

    Solar thermal energy conversion has attracted substantial renewed interest due to its applications in industrial heating, air conditioning, and electricity generation. Achieving stagnation temperatures exceeding 200 °C, pertinent to these technologies, with unconcentrated sunlight requires spectrally selective absorbers with exceptionally low emissivity in the thermal wavelength range and high visible absorptivity for the solar spectrum. In this Communication, we then report a semiconductor-based multilayer selective absorber that exploits the sharp drop in optical absorption at the bandgap energy to achieve a measured absorptance of 76% at solar wavelengths and a low emittance of approximately 5% at thermal wavelengths. In fieldmore » tests, we obtain a peak temperature of 225 °C, comparable to that achieved with state-of-the-art selective surfaces. Furthemore, with straightforward optimization to improve solar absorption, our work shows the potential for unconcentrated solar thermal systems to reach stagnation temperatures exceeding 300 °C, thereby eliminating the need for solar concentrators for mid-temperature solar applications such as supplying process heat« less

  20. A DPL model of photo-thermal interaction in an infinite semiconductor material containing a spherical hole

    NASA Astrophysics Data System (ADS)

    Hobiny, Aatef D.; Abbas, Ibrahim A.

    2018-01-01

    The dual phase lag (DPL) heat transfer model is applied to study the photo-thermal interaction in an infinite semiconductor medium containing a spherical hole. The inner surface of the cavity was traction free and loaded thermally by pulse heat flux. By using the eigenvalue approach methodology and Laplace's transform, the physical variable solutions are obtained analytically. The numerical computations for the silicon-like semiconductor material are obtained. The comparison among the theories, i.e., dual phase lag (DPL), Lord and Shulman's (LS) and the classically coupled thermoelastic (CT) theory is presented graphically. The results further show that the analytical scheme can overcome mathematical problems by analyzing these problems.

  1. Thermal Scanning of Dental Pulp Chamber by Thermocouple System and Infrared Camera during Photo Curing of Resin Composites

    PubMed Central

    Hamze, Faeze; Ganjalikhan Nasab, Seyed Abdolreza; Eskandarizadeh, Ali; Shahravan, Arash; Akhavan Fard, Fatemeh; Sinaee, Neda

    2018-01-01

    Introduction: Due to thermal hazard during composite restorations, this study was designed to scan the pulp temperature by thermocouple and infrared camera during photo polymerizing different composites. Methods and Materials: A mesio-occlso-distal (MOD) cavity was prepared in an extracted tooth and the K-type thermocouple was fixed in its pulp chamber. Subsequently, 1 mm increment of each composites were inserted (four composite types were incorporated) and photo polymerized employing either LED or QTH systems for 60 sec while the temperature was recorded with 10 sec intervals. Ultimately, the same tooth was hemisected bucco-lingually and the amalgam was removed. The same composite curing procedure was repeated while the thermogram was recorded using an infrared camera. Thereafter, the data was analyzed by repeated measured ANOVA followed by Tukey’s HSD Post Hoc test for multiple comparisons (α=0.05). Results: The pulp temperature was significantly increased (repeated measures) during photo polymerization (P=0.000) while there was no significant difference among the results recorded by thermocouple comparing to infrared camera (P>0.05). Moreover, different composite materials and LCUs lead to similar outcomes (P>0.05). Conclusion: Although various composites have significant different chemical compositions, they lead to similar pulp thermal changes. Moreover, both the infrared camera and the thermocouple would record parallel results of dental pulp temperature. PMID:29707014

  2. Photo-oxidation of polymer-like amorphous hydrogenated carbon under visible light illumination

    DOE PAGES

    Baxamusa, Salmaan; Laurence, Ted; Worthington, Matthew; ...

    2015-11-10

    Amorphous hydrogenated carbon (a-C:H), a polymer-like network typically synthesized by plasma chemical vapor deposition, has long been understood to exhibit optical absorption of visible light (λ > 400 nm). In this report we explain that this absorption is accompanied by rapid photo-oxidation (within minutes) that behaves in most respects like classic polymer photo-oxidation with the exception that it occurs under visible light illumination rather than ultraviolet illumination.

  3. Semantic photo books: leveraging blogs and social media for photo book creation

    NASA Astrophysics Data System (ADS)

    Rabbath, Mohamad; Sandhaus, Philipp; Boll, Susanne

    2011-03-01

    Recently, we observed a substantial increase in the users' interest in sharing their photos online in travel blogs, social communities and photo sharing websites. An interesting aspect of these web platforms is their high level of user-media interaction and thus a high-quality source of semantic annotations: Users comment on the photos of each others, add external links to their travel blogs, tag each other in the social communities and add captions and descriptions to their photos. However, while those media assets are shared online, many users still highly appreciate the representation of these media in appealing physical photo books where the semantics are represented in form of descriptive text, maps, and external elements in addition to their related photos. Thus, in this paper we aim at fulfilling this need and provide an approach for creating photo books from Web 2.0 resources. We concentrate on two kinds of online shared media as resources for printable photo books: (a) Blogs especially travel blogs (b) Social community websites like Facebook which witness a rapidly growing number of shared media elements including photos. We introduce an approach to select media elements including photos, geographical maps and texts from both blogs and social networks semi-automatically, and then use these elements to create a printable photo book with an appealing layout. Because the selected media elements can be too many for the resulting book, we choose the most proper ones by exploiting content based, social based, and interactive based criteria. Additionally we add external media elements such as geographical maps, texts and externally hosted photos from linked resources. Having selected the important media, our approach uses a genetic algorithm to create an appealing layout using aesthetical rules, such as positioning the photo with the related text or map in a way that respects the golden ratio and symmetry. Distributing the media over the pages is done by

  4. A highly efficient CMOS nanoplasmonic crystal enhanced slow-wave thermal emitter improves infrared gas-sensing devices

    PubMed Central

    Pusch, Andreas; De Luca, Andrea; Oh, Sang S.; Wuestner, Sebastian; Roschuk, Tyler; Chen, Yiguo; Boual, Sophie; Ali, Zeeshan; Phillips, Chris C.; Hong, Minghui; Maier, Stefan A.; Udrea, Florin; Hopper, Richard H.; Hess, Ortwin

    2015-01-01

    The application of plasmonics to thermal emitters is generally assisted by absorptive losses in the metal because Kirchhoff’s law prescribes that only good absorbers make good thermal emitters. Based on a designed plasmonic crystal and exploiting a slow-wave lattice resonance and spontaneous thermal plasmon emission, we engineer a tungsten-based thermal emitter, fabricated in an industrial CMOS process, and demonstrate its markedly improved practical use in a prototype non-dispersive infrared (NDIR) gas-sensing device. We show that the emission intensity of the thermal emitter at the CO2 absorption wavelength is enhanced almost 4-fold compared to a standard non-plasmonic emitter, which enables a proportionate increase in the signal-to-noise ratio of the CO2 gas sensor. PMID:26639902

  5. Characterizing the thermal distributions of warm molecular hydrogen in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Hoadley, Keri; France, Kevin

    2016-01-01

    Probing the surviving molecular gas within the inner regions of protoplanetary disks (PPDs) around T Tauri stars (1 - 10 Myr) provides insight into the conditions in which planet formation and migration occurs while the gas disk is still present. Recent studies done by Hoadley et al. 2015 and Banzatti & Pontipoddan 2015 suggest that gas in the inner disks of PPDs appear to "respond" to the loss of small dust grains with evolving PPD stage, and IR-CO emission may either be thermally or photo-excited by stellar UV radiation, depending on PPD evolutionary stage. Because far-UV H2 emission lines are dominantly photo-excited by stellar HI-Lyman alpha photons, we observe H2 absorption features against the stellar Lyman alpha wings in a large sample of PPDs at various evolutionary stages. We aim to characterize whether the inner disk H2 environment is in thermal equilibrium at various stages of PPD evolution. We use a sophisticated first-principles approach to fitting multiple absorption features along the red- and blue-wings of the observed stellar Lyman alpha profiles to extract column density estimates of H2 along the line of sight to the target. We find that the high kinetic energy H2 observed in absorption against the LyA wing may be described as a part of the thermal distribution with high kinetic temperature - a potential indication of an inner disk molecular hazy "envelope" around the cooler bulk disk. Ongoing research may help determine the state of the gas and whether it evolves with disk evolutionary stage.

  6. Multiple-frame IR photo-recorder KIT-3M

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roos, E; Wilkins, P; Nebeker, N

    2006-05-15

    This paper reports the experimental results of a high-speed multi-frame infrared camera which has been developed in Sarov at VNIIEF. Earlier [1] we discussed the possibility of creation of the multi-frame infrared radiation photo-recorder with framing frequency about 1 MHz. The basis of the photo-recorder is a semiconductor ionization camera [2, 3], which converts IR radiation of spectral range 1-10 micrometers into a visible image. Several sequential thermal images are registered by using the IR converter in conjunction with a multi-frame electron-optical camera. In the present report we discuss the performance characteristics of a prototype commercial 9-frame high-speed IR photo-recorder.more » The image converter records infrared images of thermal fields corresponding to temperatures ranging from 300 C to 2000 C with an exposure time of 1-20 {micro}s at a frame frequency up to 500 KHz. The IR-photo-recorder camera is useful for recording the time evolution of thermal fields in fast processes such as gas dynamics, ballistics, pulsed welding, thermal processing, automotive industry, aircraft construction, in pulsed-power electric experiments, and for the measurement of spatial mode characteristics of IR-laser radiation.« less

  7. The Photo-Physics of Polythiophene Nanoparticles for Biological Applications.

    PubMed

    Bargigia, Ilaria; Zucchetti, Elena; Srimath Kandada, Ajay Ram; Moreira, Miguel; Bossio, Caterina; Wong, Walter; Miranda, Paulo; Decuzzi, Paolo; Soci, Cesare; D'Andrea, Cosimo; Lanzani, Guglielmo

    2018-05-01

    In this work the photo-physics of poly(3-hexyltiophene) nanoparticles (NPs) is investigated in the context of their biological applications. The NPs made as colloidal suspensions in aqueous buffers present a distinct absorption band in the low energy region. Based on systematic analysis of absorption and transient absorption spectra taken under different pH conditions, this band is associated to charge transfer states generated by the polarization of loosely bound polymer chains and originated from complexes formed with electron withdrawing species. Importantly, the ground state depletion of these states upon photo-excitation is active even in the microsecond timescales, suggesting that they act as precursor states for long-living polarons which could be beneficial for cellular stimulation. Preliminary results of transient absorption microscopy of NPs internalized within the cells reveal the presence of long-living species, further substantiating their relevance in bio-interfaces. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Thermal neutron macroscopic absorption cross section measurement (theory, experiment and results) for small environmental samples

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Czubek, J.A.; Drozdowicz, K.; Gabanska, B.

    Czubek`s method of measurement of the thermal neutron macroscopic absorption cross section of small samples has been developed at the Henryk Niewodniczanski Institute of Nuclear Physics in Krakow, Poland. Theoretical principles of the method have been elaborated in the one-velocity diffusion approach in which the thermal neutron parameters used have been averaged over a modified Maxwellian. In consecutive measurements the investigated sample is enveloped in shells of a known moderator of varying thickness and irradiated with a pulsed beam of fast neutrons. The neutrons are slowed-down in the system and a die-away rate of escaping thermal neutrons is measured. Themore » decay constant vs. thickness of the moderator creates the experimental curve. The absorption cross section of the unknown sample is found from the intersection of this curve with the theoretical one. The theoretical curve is calculated for the case when the dynamic material buckling of the inner sample is zero. The method does not use any reference absorption standard and is independent of the transport cross section of the measured sample. The volume of the sample is form of fluid or crushed material is about 170 cm{sup 3}. The standard deviation for the measured mass absorption cross section of rock samples is in the range of 4 divided by 20% of the measured value and for brines is of the order of 0.5%.« less

  9. Optical absorption and thermal transport of individual suspended carbon nanotube bundles.

    PubMed

    Hsu, I-Kai; Pettes, Michael T; Bushmaker, Adam; Aykol, Mehmet; Shi, Li; Cronin, Stephen B

    2009-02-01

    A focused laser beam is used to heat individual single-walled carbon nanotube bundles bridging two suspended microthermometers. By measurement of the temperature rise of the two thermometers, the optical absorption of 7.4-10.3 nm diameter bundles is found to be between 0.03 and 0.44% of the incident photons in the 0.4 microm diameter laser spot. The thermal conductance of the bundle is obtained with the additional measurement of the temperature rise of the nanotubes in the laser spot from shifts in the Raman G band frequency. According to the nanotube bundle diameter determined by transmission electron microscopy, the thermal conductivity is obtained.

  10. Determination of absorption coefficient based on laser beam thermal blooming in gas-filled tube.

    PubMed

    Hafizi, B; Peñano, J; Fischer, R; DiComo, G; Ting, A

    2014-08-01

    Thermal blooming of a laser beam propagating in a gas-filled tube is investigated both analytically and experimentally. A self-consistent formulation taking into account heating of the gas and the resultant laser beam spreading (including diffraction) is presented. The heat equation is used to determine the temperature variation while the paraxial wave equation is solved in the eikonal approximation to determine the temporal and spatial variation of the Gaussian laser spot radius, Gouy phase (longitudinal phase delay), and wavefront curvature. The analysis is benchmarked against a thermal blooming experiment in the literature using a CO₂ laser beam propagating in a tube filled with air and propane. New experimental results are presented in which a CW fiber laser (1 μm) propagates in a tube filled with nitrogen and water vapor. By matching laboratory and theoretical results, the absorption coefficient of water vapor is found to agree with calculations using MODTRAN (the MODerate-resolution atmospheric TRANsmission molecular absorption database) and HITRAN (the HIgh-resolution atmospheric TRANsmission molecular absorption database).

  11. On the Influence of the Sample Absorptivity when Studying the Thermal Degradation of Materials

    PubMed Central

    Boulet, Pascal; Brissinger, Damien; Collin, Anthony; Acem, Zoubir; Parent, Gilles

    2015-01-01

    The change in absorptivity during the degradation process of materials is discussed, and its influence as one of the involved parameters in the degradation models is studied. Three materials with very different behaviors are used for the demonstration of its role: a carbon composite material, which is opaque, almost grey, a plywood slab, which is opaque and spectral-dependent and a clear PMMA slab, which is semitransparent. Data are analyzed for virgin and degraded materials at different steps of thermal degradation. It is seen that absorptivity and emissivity often reach high values in the range of 0.90–0.95 with a near-grey behavior after significant thermal aggression, but depending on the materials of interest, some significant evolution may be first observed, especially during the early stages of the degradation. Supplementary inaccuracy can come from the heterogeneity of the incident flux on the slab. As a whole, discrepancies up to 20% can be observed on the absorbed flux depending on the degradation time, mainly because of the spectral variations of the absorption and up to 10% more, depending on the position on the slab. Simple models with a constant and unique value of absorptivity may then lead to inaccuracies in the evaluation of the radiative flux absorption, with possible consequences on the pyrolysis analysis, especially for properties related to the early step of the degradation process, like the time to ignition, for example. PMID:28793512

  12. On the Influence of the Sample Absorptivity when Studying the Thermal Degradation of Materials.

    PubMed

    Boulet, Pascal; Brissinger, Damien; Collin, Anthony; Acem, Zoubir; Parent, Gilles

    2015-08-21

    The change in absorptivity during the degradation process of materials is discussed, and its influence as one of the involved parameters in the degradation models is studied. Three materials with very different behaviors are used for the demonstration of its role: a carbon composite material, which is opaque, almost grey, a plywood slab, which is opaque and spectral-dependent and a clear PMMA slab, which is semitransparent. Data are analyzed for virgin and degraded materials at different steps of thermal degradation. It is seen that absorptivity and emissivity often reach high values in the range of 0.90-0.95 with a near-grey behavior after significant thermal aggression, but depending on the materials of interest, some significant evolution may be first observed, especially during the early stages of the degradation. Supplementary inaccuracy can come from the heterogeneity of the incident flux on the slab. As a whole, discrepancies up to 20% can be observed on the absorbed flux depending on the degradation time, mainly because of the spectral variations of the absorption and up to 10% more, depending on the position on the slab. Simple models with a constant and unique value of absorptivity may then lead to inaccuracies in the evaluation of the radiative flux absorption, with possible consequences on the pyrolysis analysis, especially for properties related to the early step of the degradation process, like the time to ignition, for example.

  13. Graphitic carbon nitride (g-C3N4) coated titanium oxide nanotube arrays with enhanced photo-electrochemical performance.

    PubMed

    Sun, Mingxuan; Fang, Yalin; Kong, Yuanyuan; Sun, Shanfu; Yu, Zhishui; Umar, Ahmad

    2016-08-09

    Herein, we report the successful formation of graphitic carbon nitride coated titanium oxide nanotube array thin films (g-C3N4/TiO2) via the facile thermal treatment of anodized Ti sheets over melamine. The proportion of C3N4 and TiO2 in the composite can be adjusted by changing the initial addition mass of melamine. The as-prepared samples are characterized by several techniques in order to understand the morphological, structural, compositional and optical properties. UV-vis absorption studies exhibit a remarkable red shift for the g-C3N4/TiO2 thin films as compared to the pristine TiO2 nanotubes. Importantly, the prepared composites exhibit an enhanced photocurrent and photo-potential under both UV-vis and visible light irradiation. Moreover, the observed maximum photo-conversion efficiency of the prepared composites is 1.59 times higher than that of the pristine TiO2 nanotubes. The optical and electrochemical impedance spectra analysis reveals that the better photo-electrochemical performance of the g-C3N4/TiO2 nanotubes is mainly due to the wider light absorption and reduced impedance compared to the bare TiO2 nanotube electrode. The presented work demonstrates a facile and simple method to fabricate g-C3N4/TiO2 nanotubes and clearly revealed that the introduction of g-C3N4 is a new and innovative approach to improve the photocurrent and photo-potential efficiencies of TiO2.

  14. Subsurface thermal behaviour of tissue mimics embedded with large blood vessels during plasmonic photo-thermal therapy.

    PubMed

    Paul, Anup; Narasimhan, Arunn; Das, Sarit K; Sengupta, Soujit; Pradeep, Thalappil

    2016-11-01

    The purpose of this study was to understand the subsurface thermal behaviour of a tissue phantom embedded with large blood vessels (LBVs) when exposed to near-infrared (NIR) radiation. The effect of the addition of nanoparticles to irradiated tissue on the thermal sink behaviour of LBVs was also studied. Experiments were performed on a tissue phantom embedded with a simulated blood vessel of 2.2 mm outer diameter (OD)/1.6 mm inner diameter (ID) with a blood flow rate of 10 mL/min. Type I collagen from bovine tendon and agar gel were used as tissue. Two different nanoparticles, gold mesoflowers (AuMS) and graphene nanostructures, were synthesised and characterised. Energy equations incorporating a laser source term based on multiple scattering theories were solved using finite element-based commercial software. The rise in temperature upon NIR irradiation was seen to vary according to the position of the blood vessel and presence of nanoparticles. While the maximum rise in temperature was about 10 °C for bare tissue, it was 19 °C for tissue embedded with gold nanostructures and 38 °C for graphene-embedded tissues. The axial temperature distribution predicted by computational simulation matched the experimental observations. A different subsurface temperature distribution has been obtained for different tissue vascular network models. The position of LBVs must be known in order to achieve optimal tissue necrosis. The simulation described here helps in predicting subsurface temperature distributions within tissues during plasmonic photo-thermal therapy so that the risks of damage and complications associated with in vivo experiments and therapy may be avoided.

  15. High Rate Production of Clean Water Based on the Combined Photo-Electro-Thermal Effect of Graphene Architecture.

    PubMed

    Cui, Linfan; Zhang, Panpan; Xiao, Yukun; Liang, Yuan; Liang, Hanxue; Cheng, Zhihua; Qu, Liangti

    2018-05-01

    The use of abundant solar energy for regeneration and desalination of water is a promising strategy to address the challenge of a global shortage of clean water. Progress has been made to develop photothermal materials to improve the solar steam generation performance. However, the mass production rate of water is still low. Herein, by a rational combination of photo-electro-thermal effect on an all-graphene hybrid architecture, solar energy can not only be absorbed fully and transferred into heat, but also converted into electric power to further heat up the graphene skeleton frame for a much enhanced generation of water vapor. As a result, the unique graphene evaporator reaches a record high water production rate of 2.01-2.61 kg m -2 h -1 under solar illumination of 1 kW m -2 even without system optimization. Several square meters of the graphene evaporators will provide a daily water supply that is enough for tens of people. The combination of photo-electro-thermal effect on graphene materials offers a new strategy to build a fast and scalable solar steam generation system, which makes an important step towards a solution for the scarcity of clean water. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Understanding and improving photo-control of ion channels in nociceptors with azobenzene photo-switches.

    PubMed

    Mourot, Alexandre; Herold, Christian; Kienzler, Michael A; Kramer, Richard H

    2017-06-20

    The photo-isomerizable local anaesthetic, quaternary ammonium-azobenzene-quaternary ammonium (QAQ), provides rapid, optical control over pain signalling without involving genetic modification. In darkness or in green light, trans-QAQ blocks voltage-gated K + and Na + channels and silences action potentials in pain-sensing neurons. Upon photo-isomerization to cis with near UV light, QAQ blockade is rapidly relieved, restoring neuronal activity. However, the molecular mechanism of cis and trans QAQ blockade is not known. Moreover, the absorption spectrum of QAQ requires UV light for photo-control, precluding use deep inside neural tissue. Electrophysiology and molecular modelling were used to characterize the binding of cis and trans QAQ to voltage-gated K + channels and to develop quaternary ammonium-ethylamine-azobenzene-quaternary ammonium (QENAQ), a red-shifted QAQ derivative controlled with visible light. trans QAQ was sixfold more potent than cis QAQ, in blocking current through Shaker K + channels. Both isomers were use-dependent, open channel blockers, binding from the cytoplasmic side, but only trans QAQ block was slightly voltage dependent. QENAQ also blocked native K + and Na + channels preferentially in the trans state. QENAQ was photo-isomerized to cis with blue light and spontaneously reverted to trans within seconds in darkness, enabling rapid photo-control of action potentials in sensory neurons. Light-switchable local anaesthetics provide a means to non-invasively photo-control pain signalling with high selectivity and fast kinetics. Understanding the mode of action of QAQ and related compounds will help to design of drugs with improved photo-pharmacological properties. © 2017 The British Pharmacological Society.

  17. Maskless direct laser writing with visible light: Breaking through the optical resolving limit with cooperative manipulations of nonlinear reverse saturation absorption and thermal diffusion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wei, Jingsong, E-mail: weijingsong@siom.ac.cn; Wang, Rui; University of Chinese Academy of Sciences, Beijing 100049

    In this work, the resolving limit of maskless direct laser writing is overcome by cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion, where the nonlinear reverse saturation absorption can induce the formation of below diffraction-limited energy absorption spot, and the thermal diffusion manipulation can make the heat quantity at the central region of energy absorption spot propagate along the thin film thickness direction. The temperature at the central region of energy absorption spot transiently reaches up to melting point and realizes nanolithography. The sample “glass substrate/AgInSbTe” is prepared, where AgInSbTe is taken as nonlinear reverse saturation absorption thinmore » film. The below diffraction-limited energy absorption spot is simulated theoretically and verified experimentally by near-field spot scanning method. The “glass substrate/Al/AgInSbTe” sample is prepared, where the Al is used as thermal conductive layer to manipulate the thermal diffusion channel because the thermal diffusivity coefficient of Al is much larger than that of AgInSbTe. The direct laser writing is conducted by a setup with a laser wavelength of 650 nm and a converging lens of NA=0.85, the lithographic marks with a size of about 100 nm are obtained, and the size is only about 1/10 the incident focused spot. The experimental results indicate that the cooperative manipulation from nonlinear reverse saturation absorption and thermal diffusion is a good method to realize nanolithography in maskless direct laser writing with visible light.« less

  18. Effects of temperature-dependent molecular absorption coefficients on the thermal infrared remote sensing of the earth surface

    NASA Technical Reports Server (NTRS)

    Wan, Zhengming; Dozier, Jeff

    1992-01-01

    The effect of temperature-dependent molecular absorption coefficients on thermal infrared spectral signatures measured from satellite sensors is investigated by comparing results from the atmospheric transmission and radiance codes LOWTRAN and MODTRAN and the accurate multiple scattering radiative transfer model ATRAD for different atmospheric profiles. The sensors considered include the operational NOAA AVHRR and two research instruments planned for NASA's Earth Observing System (EOS): MODIS-N (Moderate Resolution Imaging Spectrometer-Nadir-Mode) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer). The difference in band transmittance is as large as 6 percent for some thermal bands within atmospheric windows and more than 30 percent near the edges of these atmospheric windows. The effect of temperature-dependent molecular absorption coefficients on satellite measurements of sea-surface temperature can exceed 0.6 K. Quantitative comparison and factor analysis indicate that more accurate measurements of molecular absorption coefficients and better radiative transfer simulation methods are needed to achieve SST accuracy of 0.3 K, as required for global numerical models of climate, and to develop land-surface temperature algorithms at the 1-K accuracy level.

  19. Lattice parameter evolution in Pt nanoparticles during photo-thermally induced sintering and grain growth

    DOE PAGES

    Kelly, B.G.; Loether, A.; DiChiara, A. D.; ...

    2017-04-20

    An in-situ optical pump/x-ray probe technique has been used to study the size dependent lattice parameter of Pt nanoparticles subjected to picosecond duration optical laser pulses. The as-prepared Pt nanoparticles exhibited a contracted lattice parameter consistent with the response of an isolated elastic sphere to a compressive surface stress. During photo-thermally induced sintering and grain growth, however, the Pt lattice parameter did not evolve with the inverse particle size dependence predicted by simple surface stress models. Lastly, the observed behavior could be attributed to the combined effects of a compressive surface/interface stress and a tensile stress arising from intergranular material.

  20. Lattice parameter evolution in Pt nanoparticles during photo-thermally induced sintering and grain growth

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kelly, B.G.; Loether, A.; DiChiara, A. D.

    An in-situ optical pump/x-ray probe technique has been used to study the size dependent lattice parameter of Pt nanoparticles subjected to picosecond duration optical laser pulses. The as-prepared Pt nanoparticles exhibited a contracted lattice parameter consistent with the response of an isolated elastic sphere to a compressive surface stress. During photo-thermally induced sintering and grain growth, however, the Pt lattice parameter did not evolve with the inverse particle size dependence predicted by simple surface stress models. Lastly, the observed behavior could be attributed to the combined effects of a compressive surface/interface stress and a tensile stress arising from intergranular material.

  1. Unified Photo Enhancement by Discovering Aesthetic Communities From Flickr.

    PubMed

    Hong, Richang; Zhang, Luming; Tao, Dacheng

    2016-03-01

    Photo enhancement refers to the process of increasing the aesthetic appeal of a photo, such as changing the photo aspect ratio and spatial recomposition. It is a widely used technique in the printing industry, graphic design, and cinematography. In this paper, we propose a unified and socially aware photo enhancement framework which can leverage the experience of photographers with various aesthetic topics (e.g., portrait and landscape). We focus on photos from the image hosting site Flickr, which has 87 million users and to which more than 3.5 million photos are uploaded daily. First, a tagwise regularized topic model is proposed to describe the aesthetic topic of each Flickr user, and coherent and interpretable topics are discovered by leveraging both the visual features and tags of photos. Next, a graph is constructed to describe the similarities in aesthetic topics between the users. Noticeably, densely connected users have similar aesthetic topics, which are categorized into different communities by a dense subgraph mining algorithm. Finally, a probabilistic model is exploited to enhance the aesthetic attractiveness of a test photo by leveraging the photographic experiences of Flickr users from the corresponding communities of that photo. Paired-comparison-based user studies show that our method performs competitively on photo retargeting and recomposition. Moreover, our approach accurately detects aesthetic communities in a photo set crawled from nearly 100000 Flickr users.

  2. The Reverse Thermal Effect in Epoxy Resins and Moisture Absorption in Semi-Interpenetrating Polymer Networks.

    NASA Astrophysics Data System (ADS)

    El-Sa'Ad, Leila

    1989-12-01

    termed the "reverse thermal effect". The swelling results suggested that it is more tightly bound water in the polymer which takes part in the reverse thermal effect. The absorption results for the Semi-Interpenetrating Polymer Networks suggested that the two key parameters which affected the moisture uptake were the morphology of the network and the percentage of epoxy resin in the system.

  3. Modeling the thermo-acoustic effects of thermal-dependent speed of sound and acoustic absorption of biological tissues during focused ultrasound hyperthermia.

    PubMed

    López-Haro, S A; Gutiérrez, M I; Vera, A; Leija, L

    2015-10-01

    To evaluate the effects of thermal dependence of speed of sound (SOS) and acoustic absorption of biological tissues during noninvasive focused ultrasound (US) hyperthermia therapy. A finite element (FE) model was used to simulate hyperthermia therapy in the liver by noninvasive focused US. The model consisted of an ultrasonic focused transducer radiating a four-layer biological medium composed of skin, fat, muscle, and liver. The acoustic field and temperature distribution along the layers were obtained after 15 s of hyperthermia therapy using the bio-heat equation. The model solution was found with and without the thermal dependence of SOS and acoustic absorption of biological tissues. The inclusion of the thermal dependence of the SOS generated an increment of 0.4 mm in the longitudinal focus axis of the acoustic field. Moreover, results indicate an increment of the hyperthermia area (zone with temperature above 43 °C), and a maximum temperature difference of almost 3.5 °C when the thermal dependence of absorption was taken into account. The increment of the achieved temperatures at the treatment zone indicated that the effects produced by the thermal dependence of SOS and absorption must be accounted for when planning hyperthermia treatment in order to avoid overheating undesired regions.

  4. Photometric redshift estimation based on data mining with PhotoRApToR

    NASA Astrophysics Data System (ADS)

    Cavuoti, S.; Brescia, M.; De Stefano, V.; Longo, G.

    2015-03-01

    Photometric redshifts (photo-z) are crucial to the scientific exploitation of modern panchromatic digital surveys. In this paper we present PhotoRApToR (Photometric Research Application To Redshift): a Java/C ++ based desktop application capable to solve non-linear regression and multi-variate classification problems, in particular specialized for photo-z estimation. It embeds a machine learning algorithm, namely a multi-layer neural network trained by the Quasi Newton learning rule, and special tools dedicated to pre- and post-processing data. PhotoRApToR has been successfully tested on several scientific cases. The application is available for free download from the DAME Program web site.

  5. Plasmonic fluorescent CdSe/Cu2S hybrid nanocrystals for multichannel imaging and cancer directed photo-thermal therapy

    NASA Astrophysics Data System (ADS)

    Sheikh Mohamed, M.; Poulose, Aby Cheruvathoor; Veeranarayanan, Srivani; Romero Aburto, Rebecca; Mitcham, Trevor; Suzuki, Yuko; Sakamoto, Yasushi; Ajayan, Pulickel M.; Bouchard, Richard R.; Yoshida, Yasuhiko; Maekawa, Toru; Sakthi Kumar, D.

    2016-04-01

    A simple, crude Jatropha curcas (JC) oil-based synthesis approach, devoid of any toxic phosphine and pyrophoric ligands, to produce size and shape tuned CdSe QDs and a further copper sulfide (Cu2S) encasing is presented. The QDs exhibited excellent photoluminescent properties with narrow band gap emission. Furthermore, the Cu2S shell rendered additional cytocompatibility and stability to the hybrid nanomaterial, which are major factors for translational and clinical applications of QDs. The nanocomposites were PEGylated and folate conjugated to augment their cytoamiability and enhance their specificity towards cancer cells. The nanohybrids possess potentials for visible, near infrared (NIR), photoacoustic (PA) and computed tomography (μCT) imaging. The diverse functionality of the composite was derived from the multi-channel imaging abilities and thermal competence on NIR laser irradiation to specifically actuate the photo-thermal ablation of brain cancer cells.A simple, crude Jatropha curcas (JC) oil-based synthesis approach, devoid of any toxic phosphine and pyrophoric ligands, to produce size and shape tuned CdSe QDs and a further copper sulfide (Cu2S) encasing is presented. The QDs exhibited excellent photoluminescent properties with narrow band gap emission. Furthermore, the Cu2S shell rendered additional cytocompatibility and stability to the hybrid nanomaterial, which are major factors for translational and clinical applications of QDs. The nanocomposites were PEGylated and folate conjugated to augment their cytoamiability and enhance their specificity towards cancer cells. The nanohybrids possess potentials for visible, near infrared (NIR), photoacoustic (PA) and computed tomography (μCT) imaging. The diverse functionality of the composite was derived from the multi-channel imaging abilities and thermal competence on NIR laser irradiation to specifically actuate the photo-thermal ablation of brain cancer cells. Electronic supplementary information (ESI

  6. Multiple Representations-Based Face Sketch-Photo Synthesis.

    PubMed

    Peng, Chunlei; Gao, Xinbo; Wang, Nannan; Tao, Dacheng; Li, Xuelong; Li, Jie

    2016-11-01

    Face sketch-photo synthesis plays an important role in law enforcement and digital entertainment. Most of the existing methods only use pixel intensities as the feature. Since face images can be described using features from multiple aspects, this paper presents a novel multiple representations-based face sketch-photo-synthesis method that adaptively combines multiple representations to represent an image patch. In particular, it combines multiple features from face images processed using multiple filters and deploys Markov networks to exploit the interacting relationships between the neighboring image patches. The proposed framework could be solved using an alternating optimization strategy and it normally converges in only five outer iterations in the experiments. Our experimental results on the Chinese University of Hong Kong (CUHK) face sketch database, celebrity photos, CUHK Face Sketch FERET Database, IIIT-D Viewed Sketch Database, and forensic sketches demonstrate the effectiveness of our method for face sketch-photo synthesis. In addition, cross-database and database-dependent style-synthesis evaluations demonstrate the generalizability of this novel method and suggest promising solutions for face identification in forensic science.

  7. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, David A.; Keller, Richard A.

    1985-01-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10.sup.-5 cm.sup.-1 has been demonstrated using this technique.

  8. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1982-06-08

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be rlated to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10/sup -5/ cm/sup -1/ has been demonstrated using this technique.

  9. The enhanced photo absorption and carrier transportation of InGaN/GaN Quantum Wells for photodiode detector applications

    PubMed Central

    Yang, Haojun; Ma, Ziguang; Jiang, Yang; Wu, Haiyan; Zuo, Peng; Zhao, Bin; Jia, Haiqiang; Chen, Hong

    2017-01-01

    We have conducted a series of measurements of resonantly excited photoluminescence, photocurrent and photovoltage on InGaN/GaN quantum wells with and without a p-n junction under reverse bias condition. The results indicate that most of the resonantly excited photo-generated carriers are extracted from the quantum wells when a p-n junction exists, and the photon absorption of quantum wells is enhanced by the p-n junction. Additionally, the carrier extraction becomes more distinct under a reverse bias. Our finding brings better understanding of the physical characteristics of quantum wells with p-n junction, which also suggests that the quantum well is suitable for photodiode detectors applications when a p-n junction is used. PMID:28240254

  10. Photo-induced degradation of some flavins in aqueous solution

    NASA Astrophysics Data System (ADS)

    Holzer, W.; Shirdel, J.; Zirak, P.; Penzkofer, A.; Hegemann, P.; Deutzmann, R.; Hochmuth, E.

    2005-01-01

    The blue-light induced photo-degradation of FMN, FAD, riboflavin, lumiflavin, and lumichrome in aqueous solution at pH 8 is studied by measurement of absorption coefficient spectral changes due to continuous excitation at 428 nm. The quantum yields of photo-degradation determined are ϕD(riboflavin, pH 8) ≈ 7.8 × 10 -3, ϕD(FMN, pH 5.6) ≈ 7.3 × 10 -3, ϕD(FMN, pH 8) ≈ 4.6 × 10 -3, ϕD(FAD, pH 8) ≈ 3.7 × 10 -4, ϕD(lumichrome, pH 8) ≈ 1.8 × 10 -4, and ϕD(lumiflavin, pH 8) ⩽ 1.1 × 10 -5. In a mass-spectroscopic analysis, the photo-products of FMN dissolved in water (solution pH is 5.6) were identified to be lumichrome and the lumiflavin derivatives dihydroxymethyllumiflavin, formyllumiflavin, and lumiflavin-hydroxy-acetaldehyde. An absorption and emission spectroscopic characterisation of the primary photoproducts of FMN at pH 8 is carried out.

  11. Effects of γ-ray irradiation on optical absorption and laser damage performance of KDP crystals containing arsenic impurities.

    PubMed

    Guo, D C; Jiang, X D; Huang, J; Wang, F R; Liu, H J; Xiang, X; Yang, G X; Zheng, W G; Zu, X T

    2014-11-17

    The effects of γ-irradiation on potassium dihydrogen phosphate crystals containing arsenic impurities are investigated with different optical diagnostics, including UV-VIS absorption spectroscopy, photo-thermal common-path interferometer and photoluminescence spectroscopy. The optical absorption spectra indicate that a new broad absorption band near 260 nm appears after γ-irradiation. It is found that the intensity of absorption band increases with the increasing irradiation dose and arsenic impurity concentration. The simulation of radiation defects show that this absorption is assigned to the formation of AsO₄⁴⁻ centers due to arsenic ions substituting for phosphorus ions. Laser-induced damage threshold test is conducted by using 355 nm nanosecond laser pulses. The correlations between arsenic impurity concentration and laser induced damage threshold are presented. The results indicate that the damage performance of the material decreases with the increasing arsenic impurity concentration. Possible mechanisms of the irradiation-induced defects formation under γ-irradiation of KDP crystals are discussed.

  12. Photo-generated carriers lose energy during extraction from polymer-fullerene solar cells

    PubMed Central

    Melianas, Armantas; Etzold, Fabian; Savenije, Tom J.; Laquai, Frédéric; Inganäs, Olle; Kemerink, Martijn

    2015-01-01

    In photovoltaic devices, the photo-generated charge carriers are typically assumed to be in thermal equilibrium with the lattice. In conventional materials, this assumption is experimentally justified as carrier thermalization completes before any significant carrier transport has occurred. Here, we demonstrate by unifying time-resolved optical and electrical experiments and Monte Carlo simulations over an exceptionally wide dynamic range that in the case of organic photovoltaic devices, this assumption is invalid. As the photo-generated carriers are transported to the electrodes, a substantial amount of their energy is lost by continuous thermalization in the disorder broadened density of states. Since thermalization occurs downward in energy, carrier motion is boosted by this process, leading to a time-dependent carrier mobility as confirmed by direct experiments. We identify the time and distance scales relevant for carrier extraction and show that the photo-generated carriers are extracted from the operating device before reaching thermal equilibrium. PMID:26537357

  13. Synthesis and Thermal and Photo Behaviors of New Polyamide/Organocaly Nanocomposites Containing Para Phenylenediacrylic Moiety

    NASA Astrophysics Data System (ADS)

    Faghihi, Khalil; Soleimani, Masoumeh; Shabanian, Meisam; Abootalebi, Ashraf Sadat

    2011-06-01

    New type of aromatic polyamide/montmorillonite nanocomposites were produced using solution process in N-methyl-2-pyrolidone. Amide chains were synthesized from 4,4'-diaminodiphenyl sulfone and p-phenylenediacrylic acid in N-methyl-2-pyrolidone. The resulting nanocomposite films containing 5-15 mass % of organoclay were characterized for FT-IR, scanning electronmicroscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), optical transparency and water absorption measurements. The distribution of organoclay and nanostructure of the composites were investigated by (XRD) and SEM analyses. Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. The percentage optical transparency and water absorption of these hybrids was found to be much reduced upon the addition of modified layered silicate indicating decreased permeability.

  14. Signatures of Hot Molecular Hydrogen Absorption from Protoplanetary Disks. I. Non-thermal Populations

    NASA Astrophysics Data System (ADS)

    Hoadley, Keri; France, Kevin; Arulanantham, Nicole; Loyd, R. O. Parke; Kruczek, Nicholas

    2017-09-01

    The environment around protoplanetary disks (PPDs) regulates processes that drive the chemical and structural evolution of circumstellar material. We perform a detailed empirical survey of warm molecular hydrogen (H2) absorption observed against H I-Lyα (Lyα: λ1215.67) emission profiles for 22 PPDs, using archival Hubble Space Telescope ultraviolet (UV) spectra to identify H2 absorption signatures and quantify the column densities of H2 ground states in each sightline. We compare thermal equilibrium models of H2 to the observed H2 rovibrational level distributions. We find that, for the majority of targets, there is a clear deviation in high-energy states (T exc ≳ 20,000 K) away from thermal equilibrium populations (T(H2) ≳ 3500 K). We create a metric to estimate the total column density of non-thermal H2 (N(H2)nLTE) and find that the total column densities of thermal (N(H2)) and N(H2)nLTE correlate for transition disks and targets with detectable C IV-pumped H2 fluorescence. We compare N(H2) and N(H2)nLTE to circumstellar observables and find that N(H2)nLTE correlates with X-ray and far-UV luminosities, but no correlations are observed with the luminosities of discrete emission features (e.g., Lyα, C IV). Additionally, N(H2) and N(H2)nLTE are too low to account for the H2 fluorescence observed in PPDs, so we speculate that this H2 may instead be associated with a diffuse, hot, atomic halo surrounding the planet-forming disk. We create a simple photon-pumping model for each target to test this hypothesis and find that Lyα efficiently pumps H2 levels with T exc ≥ 10,000 K out of thermal equilibrium.

  15. Measurements of the total cross section of natBe with thermal neutrons from a photo-neutron source

    NASA Astrophysics Data System (ADS)

    Liu, L. X.; Wang, H. W.; Ma, Y. G.; Cao, X. G.; Cai, X. Z.; Chen, J. G.; Zhang, G. L.; Han, J. L.; Zhang, G. Q.; Hu, J. F.; Wang, X. H.; Li, W. J.; Yan, Z.; Fu, H. J.

    2017-11-01

    The total neutron cross sections of natural beryllium in the neutron energy region of 0.007 to 0.1 eV were measured by using a time-of-flight (TOF) technique at the Shanghai Institute of Applied Physics (SINAP). The low energy neutrons were obtained by moderating the high energy neutrons from a pulsed photo-neutron source generated from a 16 MeV electron linac. The time dependent neutron background component was determined by employing the 12.8 cm boron-loaded polyethylene (PEB) (5% w.t.) to block neutron TOF path and using the Monte Carlo simulation methods. The present data was compared with the fold Harvey data with the response function of the photo-neutron source (PNS, phase-1). The present measurement of total cross section of natBe for thermal neutrons based on PNS has been developed for the acquisition of nuclear data needed for the Thorium Molten Salt Reactor (TMSR).

  16. Practical considerations for solar energy thermally enhanced photo-luminescence (TEPL) (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Kruger, Nimrod; Manor, Assaf; Kurtulik, Matej; Sabapathy, Tamilarasan; Rotschild, Carmel

    2017-04-01

    While single-junction photovoltaics (PV's) are considered limited in conversion efficiency according to the Shockley-Queisser limit, concepts such as solar thermo-photovoltaics aim to harness lost heat and overcome this barrier. We claim the novel concept of Thermally Enhanced Photoluminescence (TEPL) as an easier route to achieve this goal. Here we present a practical TEPL device where a thermally insulated photo-luminescent (PL) absorber, acts as a mediator between a photovoltaic cell and the sun. This high temperature absorber emits blue-shifted PL at constant flux, then coupled to a high band gap PV cell. This scheme promotes PV conversion efficiencies, under ideal conditions, higher than 62% at temperatures lower than 1300K. Moreover, for a PV and absorber band-gaps of 1.45eV (GaAs PV's) and 1.1eV respectively, under practical conditions, solar concentration of 1000 suns, and moderate thermal insulation; the conversion efficiencies potentially exceed 46%. Some of these practical conditions belong to the realm of optical design; including high photon recycling (PR) and absorber external quantum efficiency (EQE). High EQE values, a product of the internal QE of the active PL materials and the extraction efficiency of each photon (determined by the absorber geometry and interfaces), have successfully been reached by experts in laser cooling technology. PR is the part of emitted low energy photons (in relation to the PV band-gap) that are reabsorbed and consequently reemitted with above band-gap energies. PV back-reflector reflectivity, also successfully achieved by those who design the cutting edge high efficiency PV cells, plays a major role here.

  17. Microfabrication technology by femtosecond laser direct scanning using two-photon photo-polymerization

    NASA Astrophysics Data System (ADS)

    Zhou, Ming; Liu, Li-Peng; Dai, Qi-Xun; Pan, Chuan-Peng

    2005-01-01

    Two-photon absorption (TPA) is confined at the focus under tight-focusing conditions, which provides a novel concept for micro-fabrication using two-photon photo-polymerization in resin. The development of three-dimensional micro-fabrication by femtosecond laser was introduced at first, then the merits of femtosecond two-photon photo-polymerization was expatiated. Femtosecond laser direct scanning three-dimensional (3D) micro-fabrication system was set up and corresponding controlling software was developed. We demonstrated a fabrication of three-dimensional microstructures using photo-polymerization of resin by two-photon absorption. The precision of micro-machining and the spatial resolution reached 1um because of TPA. The dependence of fabricated line width to the micro-fabrication speed was investigated. Benzene ring, CHINA and layer-by-layer of log structures were fabricated in this 3D- micro-fabrication system as examples.

  18. Photo-controllable thermoelectric properties with reversibility and photo-thermoelectric effects of tungsten trioxide accompanied by its photochromic phenomenon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Azuma, Chiori; Kawano, Takuto; Kakemoto, Hirofumi

    2014-11-07

    The addition of photo-controllable properties to tungsten trioxide (WO{sub 3}) is of interest for developing practical applications of WO{sub 3} as well as for interpreting such phenomena from scientific viewpoints. Here, a sputtered crystalline WO{sub 3} thin film generated thermoelectric power due to ultraviolet (UV) light-induced band-gap excitation and was accompanied by a photochromic reaction resulting from generating W{sup 5+} ions. The thermoelectric properties (electrical conductivity (σ) and Seebeck coefficient (S)) and coloration of WO{sub 3} could be reversibly switched by alternating the external stimulus between UV light irradiation and dark storage. After irradiating the film with UV light, σmore » increased, whereas the absolute value of S decreased, and the photochromic (coloration) reaction was detected. Notably, the opposite behavior was exhibited by WO{sub 3} after dark storage, and this reversible cycle could be repeated at least three times. Moreover, photo-thermoelectric effects (photo-conductive effect (photo-conductivity, σ{sub photo}) and photo-Seebeck effect (photo-Seebeck coefficient, S{sub photo})) were also detected in response to visible-light irradiation of the colored WO{sub 3} thin films. Under visible-light irradiation, σ{sub photo} and the absolute value of S{sub photo} increased and decreased, respectively. These effects are likely attributable to the excitation of electrons from the mid-gap visible light absorption band (W{sup 5+} state) to the conduction band of WO{sub 3}. Our findings demonstrate that the simultaneous, reversible switching of multiple properties of WO{sub 3} thin film is achieved by the application of an external stimulus and that this material exhibits photo-thermoelectric effects when irradiated with visible-light.« less

  19. Thermally induced effect on sub-band gap absorption in Ag doped CdSe thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Jagdish; Sharma, Kriti; Bharti, Shivani; Tripathi, S. K.

    2015-05-01

    Thin films of Ag doped CdSe have been prepared by thermal evaporation using inert gas condensation (IGC) method taking Argon as inert gas. The prepared thin films are annealed at 363 K for one hour. The sub-band gap absorption spectra in the as deposited and annealed thin films have been studied using constant photocurrent method (CPM). The absorption coefficient in the sub-band gap region is described by an Urbach tail in both as deposited and annealed thin films. The value of Urbach energy and number density of trap states have been calculated from the absorption coefficient in the sub-band gap region which have been found to increase after annealing treatment indicating increase in disorderness in the lattice. The energy distribution of the occupied density of states below Fermi level has also been studied using derivative procedure of absorption coefficient.

  20. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  1. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  2. Amphiphilic Imbalance and Stabilization of Block Copolymer Micelles on-Demand through Combinational Photo-Cleavage and Photo-Crosslinking.

    PubMed

    Zhang, Xuan; Wang, Youpeng; Li, Guo; Liu, Zhaotie; Liu, Zhongwen; Jiang, Jinqiang

    2017-01-01

    An amphiphilic block copolymer of poly(ethylene oxide)-b-poly((N-methacryloxy phthalimide)-co-(7-(4-vinyl-benzyloxyl)-4-methylcoumarin)) (PEO 45 -b-P(MAPI 36 -co-VBC 4 )) is designed to improve the micellar stability during the photo-triggered release of hydrophobic cargoes. Analysis of absorption and emission spectra, solution transmittance, dynamic light scattering, and transmission electron microscopy supports that polymer micelles of PEO 45 -b-P(MAPI 36 -co-VBC 4 ) upon the combinational irradiation of 365 and 254 nm light can be solubilized through the photolysis of phthalimide esters and simultaneously crosslinked via the partially reversible photo-dimerization of coumarins. The photo-triggered release experiment shows that the leakage of doxorubicin molecules from crosslinked micelles can be predictably regulated by controlling the irradiation time of 365 and 254 nm light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1985-10-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10[sup [minus]5] cm[sup [minus]1] has been demonstrated using this technique. 6 figs.

  4. Effect of thermal radiation and suction on convective heat transfer of nanofluid along a wedge in the presence of heat generation/absorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kasmani, Ruhaila Md; Bhuvaneswari, M.; Sivasankaran, S.

    2015-10-22

    An analysis is presented to find the effects of thermal radiation and heat generation/absorption on convection heat transfer of nanofluid past a wedge in the presence of wall suction. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity transformation. The resulting system is solved numerically using a fourth-order Runge–Kutta method with shooting technique. Numerical computations are carried out for different values of dimensionless parameters to predict the effects of wedge angle, thermophoresis, Brownian motion, heat generation/absorption, thermal radiation and suction. It is found that the temperature increases significantly when the value of themore » heat generation/absorption parameter increases. But the opposite observation is found for the effect of thermal radiation.« less

  5. Photo-CIDNP NMR spectroscopy of amino acids and proteins.

    PubMed

    Kuhn, Lars T

    2013-01-01

    Photo-chemically induced dynamic nuclear polarization (CIDNP) is a nuclear magnetic resonance (NMR) phenomenon which, among other things, is exploited to extract information on biomolecular structure via probing solvent-accessibilities of tryptophan (Trp), tyrosine (Tyr), and histidine (His) amino acid side chains both in polypeptides and proteins in solution. The effect, normally triggered by a (laser) light-induced photochemical reaction in situ, yields both positive and/or negative signal enhancements in the resulting NMR spectra which reflect the solvent exposure of these residues both in equilibrium and during structural transformations in "real time". As such, the method can offer - qualitatively and, to a certain extent, quantitatively - residue-specific structural and kinetic information on both the native and, in particular, the non-native states of proteins which, often, is not readily available from more routine NMR techniques. In this review, basic experimental procedures of the photo-CIDNP technique as applied to amino acids and proteins are discussed, recent improvements to the method highlighted, and future perspectives presented. First, the basic principles of the phenomenon based on the theory of the radical pair mechanism (RPM) are outlined. Second, a description of standard photo-CIDNP applications is given and it is shown how the effect can be exploited to extract residue-specific structural information on the conformational space sampled by unfolded or partially folded proteins on their "path" to the natively folded form. Last, recent methodological advances in the field are highlighted, modern applications of photo-CIDNP in the context of biological NMR evaluated, and an outlook into future perspectives of the method is given.

  6. Single-molecule detection of dihydroazulene photo-thermal reaction using break junction technique

    NASA Astrophysics Data System (ADS)

    Huang, Cancan; Jevric, Martyn; Borges, Anders; Olsen, Stine T.; Hamill, Joseph M.; Zheng, Jue-Ting; Yang, Yang; Rudnev, Alexander; Baghernejad, Masoud; Broekmann, Peter; Petersen, Anne Ugleholdt; Wandlowski, Thomas; Mikkelsen, Kurt V.; Solomon, Gemma C.; Brøndsted Nielsen, Mogens; Hong, Wenjing

    2017-05-01

    Charge transport by tunnelling is one of the most ubiquitous elementary processes in nature. Small structural changes in a molecular junction can lead to significant difference in the single-molecule electronic properties, offering a tremendous opportunity to examine a reaction on the single-molecule scale by monitoring the conductance changes. Here, we explore the potential of the single-molecule break junction technique in the detection of photo-thermal reaction processes of a photochromic dihydroazulene/vinylheptafulvene system. Statistical analysis of the break junction experiments provides a quantitative approach for probing the reaction kinetics and reversibility, including the occurrence of isomerization during the reaction. The product ratios observed when switching the system in the junction does not follow those observed in solution studies (both experiment and theory), suggesting that the junction environment was perturbing the process significantly. This study opens the possibility of using nano-structured environments like molecular junctions to tailor product ratios in chemical reactions.

  7. Absorption and emission spectroscopic characterisation of 8-amino-riboflavin

    NASA Astrophysics Data System (ADS)

    Tyagi, A.; Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.; Mack, M.; Ghisla, S.

    2009-10-01

    The flavin dye 8-amino-8-demethyl- D-riboflavin (AF) in the solvents water, DMSO, methanol, and chloroform/DMSO was studied by absorption and fluorescence spectroscopy. The first absorption band is red-shifted compared to riboflavin, and blue-shifted compared to roseoflavin (8-dimethylamino-8-demethyl-D-riboflavin). The fluorescence quantum yield of AF in the studied solvents varies between 20% and 50%. The fluorescence lifetimes were found to be in the 2-5 ns range. AF is well soluble in DMSO, weakly soluble in water and methanol, and practically insoluble in chloroform. The limited solubility causes AF aggregation, which was seen in differences between measured absorption spectra and fluorescence excitation spectra. Light scattering in the dye absorption region is discussed and approximate absorption cross-section spectra are determined from the combined measurement of transmission and fluorescence excitation spectra. The photo-stability of AF was studied by prolonged light exposure. The photo-degradation routes of AF are discussed.

  8. Thermal Pressure in Diffuse H2 Gas Measured by Herschel [C II] Emission and FUSE UV H2 Absorption

    NASA Astrophysics Data System (ADS)

    Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Pineda, J. L.

    2017-04-01

    UV absorption studies with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite have made important observations of H2 molecular gas in Galactic interstellar translucent and diffuse clouds. Observations of the 158 μm [C II] fine-structure line with Herschel trace the same H2 molecular gas in emission. We present [C II] observations along 27 lines of sight (LOSs) toward target stars of which 25 have FUSE H2 UV absorption. Two stars have only HST STIS C II λ2325 absorption data. We detect [C II] 158 μm emission features in all but one target LOS. For three target LOSs that are close to the Galactic plane, | {\\text{}}b| < 1°, we also present position-velocity maps of [C II] emission observed by Herschel Heterodyne Instrument in the Far Infrared (HIFI) in on-the-fly spectral-line mapping. We use the velocity-resolved [C II] spectra observed by the HIFI instrument toward the target LOSs observed by FUSE to identify [C II] velocity components associated with the H2 clouds. We analyze the observed velocity integrated [C II] spectral-line intensities in terms of the densities and thermal pressures in the H2 gas using the H2 column densities and temperatures measured by the UV absorption data. We present the H2 gas densities and thermal pressures for 26 target LOSs and from the [C II] intensities derive a mean thermal pressure in the range of ˜6100-7700 K cm-3 in diffuse H2 clouds. We discuss the thermal pressures and densities toward 14 targets, comparing them to results obtained using the UV absorption data for two other tracers C I and CO. Our results demonstrate the richness of the far-IR [C II] spectral data which is a valuable complement to the UV H2 absorption data for studying diffuse H2 molecular clouds. While the UV absorption is restricted to the directions of the target star, far-IR [C II] line emission offers an opportunity to employ velocity-resolved spectral-line mapping capability to study in detail the clouds’ spatial and velocity structures.

  9. A photo-cleavable biotin affinity tag for the facile release of a photo-crosslinked carbohydrate-binding protein.

    PubMed

    Chang, Tsung-Che; Adak, Avijit K; Lin, Ting-Wei; Li, Pei-Jhen; Chen, Yi-Ju; Lai, Chain-Hui; Liang, Chien-Fu; Chen, Yu-Ju; Lin, Chun-Cheng

    2016-03-15

    The use of photo-crosslinking glycoprobes represents a powerful strategy for the covalent capture of labile protein complexes and allows detailed characterization of carbohydrate-mediated interactions. The selective release of target proteins from solid support is a key step in functional proteomics. We envisaged that light activation can be exploited for releasing labeled protein in a dual photo-affinity probe-based strategy. To investigate this possibility, we designed a trifunctional, galactose-based, multivalent glycoprobe for affinity labeling of carbohydrate-binding proteins. The resulting covalent protein-probe adduct is attached to a photo-cleavable biotin affinity tag; the biotin moiety enables specific presentation of the conjugate on streptavidin-coated beads, and the photolabile linker allows the release of the labeled proteins. This dual probe promotes both the labeling and the facile cleavage of the target protein complexes from the solid surfaces and the remainder of the cell lysate in a completely unaltered form, thus eliminating many of the common pitfalls associated with traditional affinity-based purification methods. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Photo annealing effect on p-doped inverted organic solar cell

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lafalce, Evan; Toglia, Patrick; Lewis, Jason E.

    2014-06-28

    We report the transient positive photo annealing effect in which over 600% boost of power conversion efficiency was observed in inverted organic photovoltaic devices (OPV) made from P3HT/PCBM by spray method, after 2 hrs of constant solar AM 1.5 irradiation at low temperature. This is opposite to usual photodegradation of OPV, and cannot be explained by thermal activation alone since the mere temperature effect could only account for 30% of the enhancement. We have investigated the temperature dependence, cell geometry, oxygen influence, and conclude that, for p-doped active layer at room temperature, the predominant mechanism is photo-desorption of O{sub 2}, whichmore » eliminates electron traps and reduces space charge screening. As temperature decreases, thermal activation and deep trap-state filling start to show noticeable effect on the enhancement of photocurrent at intermediate low temperature (T = 125 K). At very low temperature, the dominant mechanism for photo annealing is trap-filling, which significantly reduces recombination between free and trapped carriers. At all temperature, photo annealing effect depends on illumination direction from cathode or anode. We also explained the large fluctuation of photocurrent by the capture/reemit of trapped electrons from shallow electron traps of O{sub 2}{sup -} generated by photo-doping. Our study has demonstrated the dynamic process of photo-doping and photo-desorption, and shown that photo annealing in vacuum can be an efficient method to improve OPV device efficiency.« less

  11. Structural, optical and photo thermal properties of Er3+:Y2O3 doped PMMA nanocomposite

    NASA Astrophysics Data System (ADS)

    Tabanli, Sevcan; Eryurek, Gonul

    2018-02-01

    Thermal decomposition technique was employed to synthesize of phosphors of yttria (Y2O3) doped with erbium (Er3+) ions. After the synthesized procedure, the nano-sized crystalline powders were annealed at 800oC for 24 h. Annealed powders were embedded in poly(methyl methacrylate) (PMMA) by free radical polymerization to fabricate nanocomposite polymer materials. The crystalline structure of the powder and doped PMMA nanocomposite samples were determined using X-ray diffraction technique. Scherrer's equation and the FW1/5/4/5M method were used to determine average crystalline size and grain size distributions, respectively. The spectroscopic properties of the powders and doped PMMA nanocomposites were studied by measuring the upconversion emission spectra under near-infrared laser excitation at room temperature. The laser-induced photo thermal behaviors of Er3+:Y2O3 nano-powders and doped PMMA nanocomposite were investigated using the fluorescence intensity ratio (FIR) technique.

  12. Photo-ignition process of multiwall carbon nanotubes and ferrocene by continuous wave Xe lamp illumination.

    PubMed

    Visconti, Paolo; Primiceri, Patrizio; Longo, Daniele; Strafella, Luciano; Carlucci, Paolo; Lomascolo, Mauro; Cretì, Arianna; Mele, Giuseppe

    2017-01-01

    This work aims to investigate and characterize the photo-ignition phenomenon of MWCNT/ferrocene mixtures by using a continuous wave (CW) xenon (Xe) light source, in order to find the power ignition threshold by employing a different type of light source as was used in previous research (i.e., pulsed Xe lamp). The experimental photo-ignition tests were carried out by varying the weight ratio of the used mixtures, luminous power, and wavelength range of the incident Xe light by using selective optical filters. For a better explanation of the photo-induced ignition process, the absorption spectra of MWCNT/ferrocene mixtures and ferrocene only were obtained. The experimental results show that the luminous power (related to the entire spectrum of the Xe lamp) needed to trigger the ignition of MWCNT/ferrocene mixtures decreases with increasing metal nanoparticles content according to previously published results when using a different type of light source (i.e., pulsed vs CW Xe light source). Furthermore, less light power is required to trigger photo-ignition when moving towards the ultraviolet (UV) region. This is in agreement with the measured absorption spectra, which present higher absorption values in the UV-vis region for both MWCNT/ferrocene mixtures and ferrocene only diluted in toluene. Finally, a chemo-physical interpretation of the ignition phenomenon is proposed whereby ferrocene photo-excitation, due to photon absorption, produces ferrocene itself in its excited form and is thus capable of promoting electron transfer to MWCNTs. In this way, the resulting radical species, FeCp2 +∙ and MWCNT - , easily react with oxygen giving rise to the ignition of MWCNT/ferrocene samples.

  13. Photo-ignition process of multiwall carbon nanotubes and ferrocene by continuous wave Xe lamp illumination

    PubMed Central

    Primiceri, Patrizio; Longo, Daniele; Strafella, Luciano; Carlucci, Paolo; Lomascolo, Mauro; Cretì, Arianna; Mele, Giuseppe

    2017-01-01

    This work aims to investigate and characterize the photo-ignition phenomenon of MWCNT/ferrocene mixtures by using a continuous wave (CW) xenon (Xe) light source, in order to find the power ignition threshold by employing a different type of light source as was used in previous research (i.e., pulsed Xe lamp). The experimental photo-ignition tests were carried out by varying the weight ratio of the used mixtures, luminous power, and wavelength range of the incident Xe light by using selective optical filters. For a better explanation of the photo-induced ignition process, the absorption spectra of MWCNT/ferrocene mixtures and ferrocene only were obtained. The experimental results show that the luminous power (related to the entire spectrum of the Xe lamp) needed to trigger the ignition of MWCNT/ferrocene mixtures decreases with increasing metal nanoparticles content according to previously published results when using a different type of light source (i.e., pulsed vs CW Xe light source). Furthermore, less light power is required to trigger photo-ignition when moving towards the ultraviolet (UV) region. This is in agreement with the measured absorption spectra, which present higher absorption values in the UV–vis region for both MWCNT/ferrocene mixtures and ferrocene only diluted in toluene. Finally, a chemo-physical interpretation of the ignition phenomenon is proposed whereby ferrocene photo-excitation, due to photon absorption, produces ferrocene itself in its excited form and is thus capable of promoting electron transfer to MWCNTs. In this way, the resulting radical species, FeCp2+∙ and MWCNT−, easily react with oxygen giving rise to the ignition of MWCNT/ferrocene samples. PMID:28144572

  14. Effect of tumor properties on energy absorption, temperature mapping, and thermal dose in 13.56-MHz radiofrequency hyperthermia.

    PubMed

    Prasad, Bibin; Kim, Subin; Cho, Woong; Kim, Suzy; Kim, Jung Kyung

    2018-05-01

    Computational techniques can enhance personalized hyperthermia-treatment planning by calculating tissue energy absorption and temperature distribution. This study determined the effect of tumor properties on energy absorption, temperature mapping, and thermal dose distribution in mild radiofrequency hyperthermia using a mouse xenograft model. We used a capacitive-heating radiofrequency hyperthermia system with an operating frequency of 13.56 MHz for in vivo mouse experiments and performed simulations on a computed tomography mouse model. Additionally, we measured the dielectric properties of the tumors and considered temperature dependence for thermal properties, metabolic heat generation, and perfusion. Our results showed that dielectric property variations were more dominant than thermal properties and other parameters, and that the measured dielectric properties provided improved temperature-mapping results relative to the property values taken from previous study. Furthermore, consideration of temperature dependency in the bio heat-transfer model allowed elucidation of precise thermal-dose calculations. These results suggested that this method might contribute to effective thermoradiotherapy planning in clinics. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Signatures of Hot Molecular Hydrogen Absorption from Protoplanetary Disks. I. Non-thermal Populations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoadley, Keri; France, Kevin; Arulanantham, Nicole

    2017-09-01

    The environment around protoplanetary disks (PPDs) regulates processes that drive the chemical and structural evolution of circumstellar material. We perform a detailed empirical survey of warm molecular hydrogen (H{sub 2}) absorption observed against H i-Ly α (Ly α : λ 1215.67) emission profiles for 22 PPDs, using archival Hubble Space Telescope ultraviolet (UV) spectra to identify H{sub 2} absorption signatures and quantify the column densities of H{sub 2} ground states in each sightline. We compare thermal equilibrium models of H{sub 2} to the observed H{sub 2} rovibrational level distributions. We find that, for the majority of targets, there is amore » clear deviation in high-energy states ( T {sub exc} ≳ 20,000 K) away from thermal equilibrium populations ( T (H{sub 2}) ≳ 3500 K). We create a metric to estimate the total column density of non-thermal H{sub 2} ( N (H{sub 2}){sub nLTE}) and find that the total column densities of thermal ( N (H{sub 2})) and N (H{sub 2}){sub nLTE} correlate for transition disks and targets with detectable C iv-pumped H{sub 2} fluorescence. We compare N (H{sub 2}) and N (H{sub 2}){sub nLTE} to circumstellar observables and find that N (H{sub 2}){sub nLTE} correlates with X-ray and far-UV luminosities, but no correlations are observed with the luminosities of discrete emission features (e.g., Ly α , C iv). Additionally, N (H{sub 2}) and N (H{sub 2}){sub nLTE} are too low to account for the H{sub 2} fluorescence observed in PPDs, so we speculate that this H{sub 2} may instead be associated with a diffuse, hot, atomic halo surrounding the planet-forming disk. We create a simple photon-pumping model for each target to test this hypothesis and find that Ly α efficiently pumps H{sub 2} levels with T {sub exc} ≥ 10,000 K out of thermal equilibrium.« less

  16. Analytical prediction of sub-surface thermal history in translucent tissue phantoms during plasmonic photo-thermotherapy (PPTT).

    PubMed

    Dhar, Purbarun; Paul, Anup; Narasimhan, Arunn; Das, Sarit K

    2016-12-01

    Knowledge of thermal history and/or distribution in biological tissues during laser based hyperthermia is essential to achieve necrosis of tumour/carcinoma cells. A semi-analytical model to predict sub-surface thermal distribution in translucent, soft, tissue mimics has been proposed. The model can accurately predict the spatio-temporal temperature variations along depth and the anomalous thermal behaviour in such media, viz. occurrence of sub-surface temperature peaks. Based on optical and thermal properties, the augmented temperature and shift of the peak positions in case of gold nanostructure mediated tissue phantom hyperthermia can be predicted. Employing inverse approach, the absorption coefficient of nano-graphene infused tissue mimics is determined from the peak temperature and found to provide appreciably accurate predictions along depth. Furthermore, a simplistic, dimensionally consistent correlation to theoretically determine the position of the peak in such media is proposed and found to be consistent with experiments and computations. The model shows promise in predicting thermal distribution induced by lasers in tissues and deduction of therapeutic hyperthermia parameters, thereby assisting clinical procedures by providing a priori estimates. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Electric Motor Thermal Management | Transportation Research | NREL

    Science.gov Websites

    Electric Motor Thermal Management Electric Motor Thermal Management A photo of a piece of of electric-drive vehicles. Photo by Kevin Bennion, NREL NREL's electric motor thermal management construction of new electric motors. Electric motor thermal management involves a multifaceted interaction of

  18. Photo-induced reduction of graphene oxide coating on optical waveguide and consequent optical intermodulation

    PubMed Central

    Chong, W. Y.; Lim, W. H.; Yap, Y. K.; Lai, C. K.; De La Rue, R. M.; Ahmad, H.

    2016-01-01

    Increased absorption of transverse-magnetic (TM) - polarised light by a graphene-oxide (GO) coated polymer waveguide has been observed in the presence of transverse-electric (TE) - polarised light. The GO-coated waveguide exhibits very strong photo-absorption of TE-polarised light - and acts as a TM-pass waveguide polariser. The absorbed TE-polarised light causes a significant temperature increase in the GO film and induces thermal reduction of the GO, resulting in an increase in optical-frequency conductivity and consequently increased optical propagation loss. This behaviour in a GO-coated waveguide gives the action of an inverted optical switch/modulator. By varying the incident TE-polarised light power, a maximum modulation efficiency of 72% was measured, with application of an incident optical power level of 57 mW. The GO-coated waveguide was able to respond clearly to modulated TE-polarised light with a pulse duration of as little as 100 μs. In addition, no wavelength dependence was observed in the response of either the modulation (TE-polarised light) or the signal (TM-polarised light). PMID:27034015

  19. Thermal exploitation of wastes with lignite for energy production.

    PubMed

    Grammelis, Panagiotis; Kakaras, Emmanuel; Skodras, George

    2003-11-01

    The thermal exploitation of wastewood with Greek lignite was investigated by performing tests in a laboratory-scale fluidized bed reactor, a 1-MW(th) semi-industrial circulating fluidized bed combustor, and an industrial boiler. Blends of natural wood, demolition wood, railroad sleepers, medium-density fiberboard residues, and power poles with lignite were used, and the co-combustion efficiency and the effect of wastewood addition on the emitted pollutants were investigated. Carbon monoxide, sulfur dioxide, and oxides of nitrogen emissions were continuously monitored, and, during the industrial-scale tests, the toxic emissions (polychlorinated dibenzodioxins and dibenzofurans and heavy metals) were determined. Ash samples were analyzed for heavy metals in an inductively coupled plasma-atomic emission spectroscopy spectrophotometer. Problems were observed during the preparation of wastewood, because species embedded with different compounds, such as railway sleepers and demolition wood, were not easily treated. All wastewood blends were proven good fuels; co-combustion proceeded smoothly and homogeneous temperature and pressure profiles were obtained. Although some fluctuations were observed, low emissions of gaseous pollutants were obtained for all fuel blends. The metal element emissions (in the flue gases and the solid residues) were lower than the legislative limits. Therefore, wastewood co-combustion with lignite can be realized, provided that the fuel handling and preparation can be practically performed in large-scale installations.

  20. Spectral Phasor approach for fingerprinting of photo-activatable fluorescent proteins Dronpa, Kaede and KikGR

    PubMed Central

    Cutrale, Francesco; Salih, Anya; Gratton, Enrico

    2013-01-01

    The phasor global analysis algorithm is common for fluorescence lifetime applications, but has only been recently proposed for spectral analysis. Here the phasor representation and fingerprinting is exploited in its second harmonic to determine the number and spectra of photo-activated states as well as their conversion dynamics. We follow the sequence of photo-activation of proteins over time by rapidly collecting multiple spectral images. The phasor representation of the cumulative images provides easy identification of the spectral signatures of each photo-activatable protein. PMID:24040513

  1. Photo-producible and photo-degradable starch/TiO2 bionanocomposite as a food packaging material: Development and characterization.

    PubMed

    Goudarzi, Vahid; Shahabi-Ghahfarrokhi, Iman

    2018-01-01

    In current study, starch/TiO 2 bionanocomposites were produced by photochemical reactions as a biodegradable food packaging material. Physical, mechanical, thermal and water-vapor permeability properties were investigated. Then, the photo-degradation properties of nanocomposite films were studied. This is the first report of the photo-producible and photo-degradable bionanocomposite as a food packaging material. Film-forming solutions were exposed to ultraviolet A (UV-A) for different times. Our results showed that UV-A irradiation increased the hydrophobicity of starch films. With increasing UV-A exposure time, tensile strength and Young's modulus of the specimens were decreased. On the other hand, elongation at break of the films was increased with increasing UV-A irradiation. The glass transition temperature and melting point of the films were increased by increasing UV-A exposure time. Nevertheless, the results showed that photo-degradation properties of photo-produced starch/TiO 2 nanocomposite were significantly higher than virgin starch and virgin starch/TiO 2 films. According to obtain results and bibliography a schema was developed to describe the mechanism of photo-production and photo-degradation of starch/TiO 2 by UV-A ray. It can be concluded, the modification of starch based biopolymer by UV-A and nano-TiO 2 , is an easy and accessible process to improve the packaging properties and photo-degradability of biopolymer based films. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Photo-conductance of a single Quantum Dot

    NASA Astrophysics Data System (ADS)

    Zimmers, Alexandre; Wang, Hongyue; Lhuillier, Emmanuel; Yu, Qian; Dubertret, Benoit; Aubin, Herve; Ulysse, Christian; LPEM Collaboration

    One promising strategy for the development of nanoscale resonant spin sensors is to measure the spin-dependent photo-current in Quantum Dots (QDots) containing spin-dependent recombination centers. To reach single spin sensitivity will require measurements of the photo-conductance of single QDots. We present here an experimental study of the conductance and photo-conductance of single HgSe QDots as function of drain and gate voltage. The evolution of the differential conductance dI/dV spectrum with the gate voltage demonstrates that single HgSe QDots are forming the junction. The amplitude of the gap measured in the differential conductance spectrum changes with the occupation level. A large inter-band gap, 0,85eV, is observed for the empty QDot, a smaller intra-band gap 0,25eV is observed for the doubly occupied QDot. These gap energies are consistent with the values extracted from the optical absorption spectrum. Upon illuminating the QDot junction, we show that the photo-conductive signal produced by this single QDot can be measured with a simple demodulation method. ANR Grant ''QUANTICON'' 10-0409-01 / DIM Nano-K / Chinese Scholarship Council.

  3. Study of thermal annealing effect on Bragg gratings photo-inscribed in step-index polymer optical fibers

    NASA Astrophysics Data System (ADS)

    Hu, X.; Kinet, D.; Mégret, P.; Caucheteur, C.

    2016-04-01

    In this paper, both non-annealed and annealed trans-4-stilbenemethanol-doped step-index polymer optical fibers were photo-inscribed using a 325 nm HeCd laser with two different beam power densities reaching the fiber core. In the high density regime where 637 mW/mm2 are used, the grating reflectivity is stable over time after the photo-writing process but the reflected spectrum is of limited quality, as the grating physical length is limited to 1.2 mm. To produce longer gratings exhibiting more interesting spectral features, the beam is enlarged to 6 mm, decreasing the power density to 127 mW/mm2. In this second regime, the grating reflectivity is not stable after the inscription process but tends to decay for both kinds of fibers. A fortunate property in this case results from the possibility to fully recover the initial reflectivity using a post-inscription thermal annealing, where the gratings are annealed at 80 °C during 2 days. The observed evolutions for both regimes are attributed to the behavior of the excited intermediate states between the excited singlet and the ground singlet state of trans- and cis-isomers as well as the temperature-dependent glassy polymer matrix.

  4. On the role of spatial position of bridged oxygen atoms as surface passivants on the ground-state gap and photo-absorption spectrum of silicon nano-crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nazemi, Sanaz; Soleimani, Ebrahim Asl; Pourfath, Mahdi, E-mail: pourfath@ut.ac.ir, E-mail: pourfath@iue.tuwien.ac.at

    2015-11-28

    Silicon nano-crystals (NCs) are potential candidates for enhancing and tuning optical properties of silicon for optoelectronic and photo-voltaic applications. Due to the high surface-to-volume ratio, however, optical properties of NC result from the interplay of quantum confinement and surface effects. In this work, we show that both the spatial position of surface terminants and their relative positions have strong effects on NC properties as well. This is accomplished by investigating the ground-state HOMO-LUMO band-gap, the photo-absorption spectra, and the localization and overlap of HOMO and LUMO orbital densities for prototype ∼1.2 nm Si{sub 32–x}H{sub 42–2x}O{sub x} hydrogenated silicon NC with bridgedmore » oxygen atoms as surface terminations. It is demonstrated that the surface passivation geometry significantly alters the localization center and thus the overlap of frontier molecular orbitals, which correspondingly modifies the electronic and optical properties of NC.« less

  5. Photo-protective mechanisms in reed canary grass to alleviate photo-inhibition of PSII on the Qinghai-Tibet Plateau.

    PubMed

    Zhang, Chao; Zhang, Da-Wei; Sun, Yan-Ni; Arfan, Muhammad; Li, Da-Xu; Yan, Jia-Jun; You, Ming-Hong; Bai, Shi-Qie; Lin, Hong-Hui

    2017-08-01

    Due to its characteristic of high biomass yield potential, there is considerable interest in cultivating Phalaris arundinacea L. cv. 'chuancaoyin No.3' (reed canary grass) on the Qinghai-Tibet Plateau where there is an abundance of alpine steppe meadow and a potential large market for animal husbandry. In this study, we 1) investigate whether reed canary grass exhibits superior productive capacity to Elymus nutans 'Aba' (E. nutans), ordinary common pasture, during the long warm days of summer at high-altitude; and 2) compare the cold tolerance between reed canary grass and E. nutans, including photosynthesis, photo-inhibition, and photo-protection. The results suggest that reed canary grass exhibits higher photosynthetic capacity compared to E. nutans at latitudes of the cool temperate zone. Meanwhile, cold-induced photo-inhibition and photo-damage at high altitudes in reed canary grass were due to both stomatal and non-stomatal limitation, and the enhancement in photo-respiration, thermal dissipation, and Mehler reaction are important processes to minimize the negative effects of high elevation and a cold environment. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  6. Benzil/triethylamine: a photo-reducing system for Cu2.

    PubMed

    Schmallegger, Max; Gescheidt, Georg

    2018-01-01

    We have investigated the photo-induced reduction of Cu 2+ -Cu 0 using benzil/triethylamine mixtures. The formation of elemental Cu is indicated by the appearance of its characteristic plasmon absorption peaks at 515 nm and 620 nm. Importantly, the nature of the counterion of the Cu 2+ salt affects the reduction process. In the presence of Cl - , the reduction proceeds faster than with SO 4 2- . Photo-induced electron transfer between excited benzil and triethylamine leads to the benzil radical anion, which acts as the reducing agent for Cu 2+ and generates Cu 0 .

  7. Evaluating HDR photos using Web 2.0 technology

    NASA Astrophysics Data System (ADS)

    Qiu, Guoping; Mei, Yujie; Duan, Jiang

    2011-01-01

    High dynamic range (HDR) photography is an emerging technology that has the potential to dramatically enhance the visual quality and realism of digital photos. One of the key technical challenges of HDR photography is displaying HDR photos on conventional devices through tone mapping or dynamic range compression. Although many different tone mapping techniques have been developed in recent years, evaluating tone mapping operators prove to be extremely difficult. Web2.0, social media and crowd-sourcing are emerging Internet technologies which can be harnessed to harvest the brain power of the mass to solve difficult problems in science, engineering and businesses. Paired comparison is used in the scientific study of preferences and attitudes and has been shown to be capable of obtaining an interval-scale ordering of items along a psychometric dimension such as preference or importance. In this paper, we exploit these technologies for evaluating HDR tone mapping algorithms. We have developed a Web2.0 style system that enables Internet users from anywhere to evaluate tone mapped HDR photos at any time. We adopt a simple paired comparison protocol, Internet users are presented a pair of tone mapped images and are simply asked to select the one that they think is better or click a "no difference" button. These user inputs are collected in the web server and analyzed by a rank aggregation algorithm which ranks the tone mapped photos according to the votes they received. We present experimental results which demonstrate that the emerging Internet technologies can be exploited as a new paradigm for evaluating HDR tone mapping algorithms. The advantages of this approach include the potential of collecting large user inputs under a variety of viewing environments rather than limited user participation under controlled laboratory environments thus enabling more robust and reliable quality assessment. We also present data analysis to correlate user generated qualitative

  8. Recent Advances in SRS on Hydrogen Isotope Separation Using Thermal Cycling Absorption Process

    DOE PAGES

    Xiao, Xin; Sessions, Henry T.; Heung, L. Kit

    2015-02-01

    The recent Thermal Cycling Absorption Process (TCAP) advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10th of the current production system’s footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects and medical isotope production.

  9. Toward a Role of Light Absorption in Initiation Chemistry of Shocked HMX single Crystals and Crystalline High Explosives

    NASA Astrophysics Data System (ADS)

    Plaksin, Igor; Rodrigues, L.

    2013-06-01

    Question which mechanism is driving radiation-induced reactions, thermal or athermal becomes a subject of conflicting discussions. Major challenge of this work is to identify at micro- (sub-granular), meso- (grain level) and macro-scale roles of these two mechanisms in triggering initiation chemistry in HMX-based HEs. Four acceptor-patterns were tested at 20 GPa input pressure: single HMX crystal-in-water, HMX/water-slurry, PBX(HMX/HTPB) & inert PBX-simulant (HMX-particles replaced by crystalline sucrose). Scenario of reaction onset-localizations-dissipation was spatially resolved using Multi-Channel Optical Analyzer MCOA-UC (96 channels, 100um-spatial accuracy, 0.2ns-timeresolution, 450-850 nm-spectral range) through real-time panoramic recording emitted reaction light and shock field in standard optic monitor. Experiments reveal a dual nature of initiation chemistry: athermal and thermal. Single-crystal tests disclose origination of photo-induced reactions downstream of emitting reaction spot due to intensified radiation absorption in surface micro-defects. Polycrystalline samples reveal cyclic reproducibility of radiation-induced thermal precursors in which radiation absorption causes thermal expansion/phase-changes of HMX-grains resulting in oscillating detonation. Work was supported by the Office of Naval Research under the ONR and ONR Global Grants N00014-12-1-0477 and N62909-12-1-7131 with Drs. Cliff Bedford and Shawn Thorne Program Managers.

  10. PhotoMorphs™: A Novel Light-Activated Reagent for Controlling Gene Expression in Zebrafish

    PubMed Central

    Tomasini, Amber J.; Schuler, Aaron D.; Zebala, John A.; Mayer, Alan N.

    2009-01-01

    Manipulating gene expression in zebrafish is critical for exploiting the full potential of this vertebrate model organism. Morpholino oligos are the most commonly employed antisense technology for knocking down gene expression. However, morpholinos suffer from a lack of control over the timing and location of knockdown. In this report, we describe a novel light-activatable knockdown reagent called PhotoMorph™. PhotoMorphs can be generated from existing morpholinos by hybridization with a complementary caging strand containing a photocleavable linkage. The caging strand neutralizes the morpholino activity until irradiation of the PhotoMorph with UV light releases the morpholino. We generated PhotoMorphs to target genes encoding enhanced green fluorescent protein (EGFP), No tail, and E-cadherin to illustrate the utility of this approach. Temporal control of gene expression with PhotoMorphs permitted us to circumvent the early lethal phenotype of E-cadherin knockdown. A splice-blocking PhotoMorph directed to the rheb gene showed light-dependent gene knockdown up to 72 hpf. PhotoMorphs thus offer a new class of laboratory reagents suitable for the spatiotemporal control of gene expression in the zebrafish. PMID:19644983

  11. Decomposed Photo Response Non-Uniformity for Digital Forensic Analysis

    NASA Astrophysics Data System (ADS)

    Li, Yue; Li, Chang-Tsun

    The last few years have seen the applications of Photo Response Non-Uniformity noise (PRNU) - a unique stochastic fingerprint of image sensors, to various types of digital forensic investigations such as source device identification and integrity verification. In this work we proposed a new way of extracting PRNU noise pattern, called Decomposed PRNU (DPRNU), by exploiting the difference between the physical andartificial color components of the photos taken by digital cameras that use a Color Filter Array for interpolating artificial components from physical ones. Experimental results presented in this work have shown the superiority of the proposed DPRNU to the commonly used version. We also proposed a new performance metrics, Corrected Positive Rate (CPR) to evaluate the performance of the common PRNU and the proposed DPRNU.

  12. Effect of a non-thermal, atmospheric-pressure, plasma brush on conversion of model self-etch adhesive formulations compared to conventional photo-polymerization

    PubMed Central

    Chen, Mingsheng; Zhang, Ying; Yao, Xiaomei; Li, Hao; Yu, Qingsong; Wang, Yong

    2012-01-01

    Objective To determine the effectiveness and efficiency of non-thermal, atmospheric plasmas for inducing polymerization of model dental self-etch adhesives. Methods The monomer mixtures used were bis-[2-(methacryloyloxy)ethyl] phosphate (2MP) and 2-hydroxyethyl methacrylate (HEMA), with mass ratios of 70/30, 50/50 and 30/70. Water was added to the above formulations: 10–30 wt%. These monomer/water mixtures were treated steadily for 40 s under a non-thermal atmospheric plasma brush working at temperatures from 32° to 35°C. For comparison, photo-initiators were added to the above formulations for photo-polymerization studies, which were light-cured for 40 s. The degree of conversion (DC) of both the plasma- and light-cured samples was measured using FTIR spectroscopy with an attenuated total reflectance attachment. Results The non-thermal plasma brush was effective in inducing polymerization of the model self-etch adhesives. The presence of water did not negatively affect the DC of plasma-cured samples. Indeed, DC values slightly increased, with increasing water content in adhesives: from 58.3% to 68.7% when the water content increased from 10% to 30% in the adhesives with a 50/50 (2MP/HEMA) mass ratio. Conversion values of the plasma-cured groups were higher than those of light-cured samples with the same mass ratio and water content. Spectral differences between the plasma- and light-cured groups indicate subtle structural distinctions in the resultant polymer networks. Significance This research if the first to demonstrate that the non-thermal plasma brush induces polymerization of model adhesives under clinical settings by direct/indirect energy transfer. This device shows promise for polymerization of dental composite restorations having enhanced properties and performance. PMID:23018084

  13. Photo-generated metamaterials induce modulation of CW terahertz quantum cascade lasers

    PubMed Central

    Mezzapesa, Francesco P.; Columbo, Lorenzo L.; Rizza, Carlo; Brambilla, Massimo; Ciattoni, Alessardro; Dabbicco, Maurizio; Vitiello, Miriam S.; Scamarcio, Gaetano

    2015-01-01

    Periodic patterns of photo-excited carriers on a semiconductor surface profoundly modifies its effective permittivity, creating a stationary all-optical quasi-metallic metamaterial. Intriguingly, one can tailor its artificial birefringence to modulate with unprecedented degrees of freedom both the amplitude and phase of a quantum cascade laser (QCL) subject to optical feedback from such an anisotropic reflector. Here, we conceive and devise a reconfigurable photo-designed Terahertz (THz) modulator and exploit it in a proof-of-concept experiment to control the emission properties of THz QCLs. Photo-exciting sub-wavelength metastructures on silicon, we induce polarization-dependent changes in the intra-cavity THz field, that can be probed by monitoring the voltage across the QCL terminals. This inherently flexible approach promises groundbreaking impact on THz photonics applications, including THz phase modulators, fast switches, and active hyperbolic media. PMID:26549166

  14. Gold Nanorod-based Photo-PCR System for One-Step, Rapid Detection of Bacteria

    PubMed Central

    Kim, Jinjoo; Kim, Hansol; Park, Ji Ho; Jon, Sangyong

    2017-01-01

    The polymerase chain reaction (PCR) has been an essential tool for diagnosis of infectious diseases, but conventional PCR still has some limitations with respect to applications to point-of-care (POC) diagnostic systems that require rapid detection and miniaturization. Here we report a light-based PCR method, termed as photo-PCR, which enables rapid detection of bacteria in a single step. In the photo-PCR system, poly(enthylene glycol)-modified gold nanorods (PEG-GNRs), used as a heat generator, are added into the PCR mixture, which is subsequently periodically irradiated with a 808-nm laser to create thermal cycling. Photo-PCR was able to significantly reduce overall thermal cycling time by integrating bacterial cell lysis and DNA amplification into a single step. Furthermore, when combined with KAPA2G fast polymerase and cooling system, the entire process of bacterial genomic DNA extraction and amplification was further shortened, highlighting the potential of photo-PCR for use in a portable, POC diagnostic system. PMID:29071186

  15. Facile synthesis and photo electrochemical performance of SnSe thin films

    NASA Astrophysics Data System (ADS)

    Pusawale, S. N.; Jadhav, P. S.; Lokhande, C. D.

    2018-05-01

    Orthorhombic structured SnSe thin films are synthesized via SILAR (successive ionic layer adsorption and reaction) method on glass substrates. The structural properties of thin films are characterized by x-ray diffraction, scanning electron microscopy studies from which nanoparticles with an elongated shape and hydrophilic behavior are observed. UV -VIS absorption spectroscopy study showed the maximum absorption in the visible region with a direct band gap of 1.55 eV. The photo electrochemical study showed p-type electrical conductivity.

  16. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  17. Allosteric Inhibitory Molecular Recognition of a Photochromic Dye by a Digestive Enzyme: Dihydroindolizine makes α-chymotrypsin Photo-responsive

    NASA Astrophysics Data System (ADS)

    Bagchi, Damayanti; Ghosh, Abhijit; Singh, Priya; Dutta, Shreyasi; Polley, Nabarun; Althagafi, Ismail. I.; Jassas, Rabab S.; Ahmed, Saleh A.; Pal, Samir Kumar

    2016-09-01

    The structural-functional regulation of enzymes by the administration of an external stimulus such as light could create photo-switches that exhibit unique biotechnological applications. However, molecular recognition of small ligands is a central phenomenon involved in all biological processes. We demonstrate herein that the molecular recognition of a photochromic ligand, dihydroindolizine (DHI), by serine protease α-chymotrypsin (CHT) leads to the photo-control of enzymatic activity. We synthesized and optically characterized the photochromic DHI. Light-induced reversible pyrroline ring opening and a consequent thermal back reaction via 1,5-electrocyclization are responsible for the photochromic behavior. Furthermore, DHI inhibits the enzymatic activity of CHT in a photo-controlled manner. Simultaneous binding of the well-known inhibitors 4-nitrophenyl anthranilate (NPA) or proflavin (PF) in the presence of DHI displays spectral overlap between the emission of CHT-NPA or CHT-PF with the respective absorption of cis or trans DHI. The results suggest an opportunity to explore the binding site of DHI using Förster resonance energy transfer (FRET). Moreover, to more specifically evaluate the DHI binding interactions, we employed molecular docking calculations, which suggested binding near the hydrophobic site of Cys-1-Cys-122 residues. Variations in the electrostatic interactions of the two conformers of DHI adopt unfavorable conformations, leading to the allosteric inhibition of enzymatic activity.

  18. Nanocarbon/elastomer composites: Characterization and applications in photo-mechanical actuation

    NASA Astrophysics Data System (ADS)

    Loomis, Robert James, III

    proportional to applied pre-strain, demonstrating mechanical coupling. Following investigation into photo-mechanical actuation responses between the various carbon forms, use of these composite actuators to achieve both macroscopic as well as microscopic movement in practical applications was evaluated. Using dual GNP/elastomer actuators, a two-axis sub-micron translation stage was developed, and allowed for two-axis photo-thermal positioning (˜100 microm per axis) with 120 nm resolution (limitation of the feedback sensor) and ˜5 microm/s actuation speeds. A proportional-integral-derivative control loop automatically stabilizes the stage against thermal drift, as well as random thermal-induced position fluctuations (up to the bandwidth of the feedback and position sensor). Nanopositioner performance characteristics were found to be on par with other commercial systems, with resolution limited only by the feedback system used. A mathematical model was developed to describe the elastomeric composite actuators as a series of n springs, with each spring element having its own independent IR-tunable spring constant. Effects of illumination intensity, position, and amount of the composite actuator illuminated are discussed. This model provided several additional insights, such as demonstrating the ability to place not just one, but multiple stages on a single polymer composite strip and position them independently from one another, a benefit not seen in any other type of positioning system. Further investigation yielded interesting and novel photo-mechanical properties with actuation visible on macroscopic scales. Addition of a third component (thermally expanding microspheres), produced a new class of stimuli-responsive expanding polymer composites with ability to unidirectionally transform physical dimensions, elastic modulus, density, and electrical resistance. Carbon nanotubes and core-shell acrylic microspheres were dispersed in polydimethylsiloxane, resulting in composites

  19. Lossless Compression of JPEG Coded Photo Collections.

    PubMed

    Wu, Hao; Sun, Xiaoyan; Yang, Jingyu; Zeng, Wenjun; Wu, Feng

    2016-04-06

    The explosion of digital photos has posed a significant challenge to photo storage and transmission for both personal devices and cloud platforms. In this paper, we propose a novel lossless compression method to further reduce the size of a set of JPEG coded correlated images without any loss of information. The proposed method jointly removes inter/intra image redundancy in the feature, spatial, and frequency domains. For each collection, we first organize the images into a pseudo video by minimizing the global prediction cost in the feature domain. We then present a hybrid disparity compensation method to better exploit both the global and local correlations among the images in the spatial domain. Furthermore, the redundancy between each compensated signal and the corresponding target image is adaptively reduced in the frequency domain. Experimental results demonstrate the effectiveness of the proposed lossless compression method. Compared to the JPEG coded image collections, our method achieves average bit savings of more than 31%.

  20. Photo-electrochemical properties of graphene wrapped hierarchically branched nanostructures obtained through hydrothermally transformed TiO2 nanotubes

    NASA Astrophysics Data System (ADS)

    Rambabu, Y.; Jaiswal, Manu; Roy, Somnath C.

    2017-10-01

    Hierarchically structured nanomaterials play an important role in both light absorption and separation of photo-generated charges. In the present study, hierarchically branched TiO2 nanostructures (HB-MLNTs) are obtained through hydrothermal transformation of electrochemically anodized TiO2 multi-leg nanotubes (MLNT) arrays. Photo-anodes based on HB-MLNTs demonstrated 5 fold increase in applied bias to photo-conversion efficiency (%ABPE) over that of TiO2 MLNTs without branches. Further, such nanostructures are wrapped with reduced graphene oxide (rGO) films to enhance the charge separation, which resulted in ∼6.5 times enhancement in %ABPE over that of bare MLNTs. We estimated charge transport (η tr) and charge transfer (η ct) efficiencies by analyzing the photo-current data. The ultra-fine nano branches grown on the MLNTs are effective in increasing light absorption through multiple scattering and improving charge transport/transfer efficiencies by enlarging semiconductor/electrolyte interface area. The charge transfer resistance, interfacial capacitance and electron decay time have been estimated through electrochemical impedance measurements which correlate with the results obtained from photocurrent measurements.

  1. Tracing nanoparticles and photosensitizing molecules at transmission electron microscopy by diaminobenzidine photo-oxidation.

    PubMed

    Malatesta, M; Pellicciari, C; Cisterna, B; Costanzo, M; Galimberti, V; Biggiogera, M; Zancanaro, C

    2014-04-01

    During the last three decades, diaminobenzidine photo-oxidation has been applied in a variety of studies to correlate light and electron microscopy. Actually, when a fluorophore is excited by light, it can induce the oxidation of diaminobenzidine into an electron-dense osmiophilic product, which precipitates in close proximity to the fluorophore, thereby allowing its ultrastructural detection. This method has very recently been developed for two innovative applications: tracking the fate of fluorescently labeled nanoparticles in single cells, and detecting the subcellular location of photo-active molecules suitable for photodynamic therapy. These studies established that the cytochemical procedures exploiting diaminobenzidine photo-oxidation represent a reliable tool for detecting, inside the cells, with high sensitivity fluorescing molecules. These procedures are trustworthy even if the fluorescing molecules are present in very low amounts, either inside membrane-bounded organelles, or at the surface of the plasma membrane, or free in the cytosol. In particular, diaminobenzidine photo-oxidation allowed elucidating the mechanisms responsible for nanoparticles internalization in neuronal cells and for their escape from lysosomal degradation. As for the photo-active molecules, their subcellular distribution at the ultrastructural level provided direct evidence for the lethal multiorganelle photo-damage occurring after cell photo-sensitization. In addition, DAB photo-oxidized samples are suitable for the ultrastructural detection of organelle-specific molecules by post-embedding gold immunolabeling. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. The Far-ultraviolet "Continuum" in Protoplanetary Disk Systems. II. Carbon Monoxide Fourth Positive Emission and Absorption

    NASA Astrophysics Data System (ADS)

    France, Kevin; Schindhelm, Eric; Burgh, Eric B.; Herczeg, Gregory J.; Harper, Graham M.; Brown, Alexander; Green, James C.; Linsky, Jeffrey L.; Yang, Hao; Abgrall, Hervé; Ardila, David R.; Bergin, Edwin; Bethell, Thomas; Brown, Joanna M.; Calvet, Nuria; Espaillat, Catherine; Gregory, Scott G.; Hillenbrand, Lynne A.; Hussain, Gaitee; Ingleby, Laura; Johns-Krull, Christopher M.; Roueff, Evelyne; Valenti, Jeff A.; Walter, Frederick M.

    2011-06-01

    We exploit the high sensitivity and moderate spectral resolution of the Hubble Space Telescope Cosmic Origins Spectrograph to detect far-ultraviolet (UV) spectral features of carbon monoxide (CO) present in the inner regions of protoplanetary disks for the first time. We present spectra of the classical T Tauri stars HN Tau, RECX-11, and V4046 Sgr, representative of a range of CO radiative processes. HN Tau shows CO bands in absorption against the accretion continuum. The CO absorption most likely arises in warm inner disk gas. We measure a CO column density and rotational excitation temperature of N(CO) = (2 ± 1) × 1017 cm-2 and T rot(CO) 500 ± 200 K for the absorbing gas. We also detect CO A-X band emission in RECX-11 and V4046 Sgr, excited by UV line photons, predominantly H I Lyα. All three objects show emission from CO bands at λ > 1560 Å, which may be excited by a combination of UV photons and collisions with non-thermal electrons. In previous observations these emission processes were not accounted for due to blending with emission from the accretion shock, collisionally excited H2, and photo-excited H2, all of which appeared as a "continuum" whose components could not be separated. The CO emission spectrum is strongly dependent upon the shape of the incident stellar Lyα emission profile. We find CO parameters in the range: N(CO) ~ 1018-1019 cm-2, T rot(CO) >~ 300 K for the Lyα-pumped emission. We combine these results with recent work on photo-excited and collisionally excited H2 emission, concluding that the observations of UV-emitting CO and H2 are consistent with a common spatial origin. We suggest that the CO/H2 ratio (≡ N(CO)/N(H2)) in the inner disk is ~1, a transition between the much lower interstellar value and the higher value observed in solar system comets today, a result that will require future observational and theoretical study to confirm. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data

  3. Photo-Luminescent Targets in Space

    NASA Technical Reports Server (NTRS)

    Maida, James; Kolomenski, Andrei

    2017-01-01

    Photo-luminescent ("glow in the dark") products have seen a dramatic increase in performance is the last 15 years with the use of a strontium aluminate formulation. Because of this, ISS uses photo-luminescent markers for interior emergency egress guidance. The marker is COTS material composed of strontium aluminate doped with europium, imbedded in PVC and achieves a light emission performance rated at 600/90 (600 mcd at 10 minutes and 90 mcd at 1 hour, 2 mcd is minimum required for human visibility). The ICA goal is to determine this material's effectiveness for use externally on ISS and/or on visiting vehicles, when packaged in Lexan for UV protection. A thermal test was conducted by EC to characterize the luminance emission profile of the material at extreme cold and hot temperatures, such as experienced on ISS.

  4. THERMAL ABSORPTION AS THE CAUSE OF GIGAHERTZ-PEAKED SPECTRA IN PULSARS AND MAGNETARS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lewandowski, Wojciech; Rożko, Karolina; Kijak, Jarosław

    2015-07-20

    We present a model that explains the observed deviation of the spectra of some pulsars and magnetars from the power-law spectra that are seen in the bulk of the pulsar population. Our model is based on the assumption that the observed variety of pulsar spectra can be naturally explained by the thermal free–free absorption that takes place in the surroundings of the pulsars. In this context, the variety of the pulsar spectra can be explained according to the shape, density, and temperature of the absorbing media and the optical path of the line of sight across it. We have putmore » specific emphasis on the case of the radio magnetar SGR J1745–2900 (also known as the Sgr A* magnetar), modeling the rapid variations of the pulsar spectrum after the outburst of 2013 April as due to the free–free absorption of the radio emission in the electron material ejected during the magnetar outburst. The ejecta expands with time and consequently the absorption rate decreases and the shape of the spectrum changes in such a way that the peak frequency shifts toward the lower radio frequencies. In the hypothesis of an absorbing medium, we also discuss the similarity between the spectral behavior of the binary pulsar B1259–63 and the spectral peculiarities of isolated pulsars.« less

  5. Dynamic mechanical thermal analysis of composite resins with CQ and PPD as photo-initiators photoactivated by QTH and LED units.

    PubMed

    Brandt, William Cunha; Silva, Cristina Gomes; Frollini, Elisabete; Souza-Junior, Eduardo Jose Carvalho; Sinhoreti, Mário Alexandre Coelho

    2013-08-01

    The aim of this study was to evaluate the thermal and mechanical properties of the composite resins containing the photo-initiators camphorquinone (CQ) and/or phenyl-propanodione (PPD) when photoactivated with halogen lamp (XL2500/3M-ESPE), monowave (UltraBlueIS/DMC) and polywave (UltraLume5/Ultradent) LED units. A blend of BisGMA, UDMA, BisEMA and TEGDMA was prepared with the same wt% of photo-initiators CQ and/or PPD and 65wt% of silaneted filler particles. Compression strength (CS), diametral tensile strength (DTS) and diametral modulus (DM) were tested. Thermogravimetric analysis (TGA) was made and the lost residual monomer were verified. Dynamic mechanical thermal analysis (DMTA) was used for to analyze the glass transition temperature (Tg) and the storage modulus in 37°C. Degree of conversion (DC) was accomplished in the same samples of DMA using middle-infrared spectroscopy (mid-IR). CQ, CQ/PPD and PPD obtained the same results for all mechanical properties (CS, DTS and DM), lost residual monomer and storage modulus in 37°C, regardless LCU used. The results of Tg showed that the combination PPD-UltraLume5 produced the highest values. DC showed that the combination CQ-UltraLume5 resulted in the highest values and PPD-XL2500 in the lowest DC values. The study shows that PPD is not only effective photosensitizers, but also photocrosslinking agents for dental composite resins with a similar efficiency to CQ. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics.

    PubMed

    Hart, Roger C; Herring, G C; Balla, R Jeffrey

    2007-06-15

    Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the streamwise velocity and static gas temperature of the same spatially resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature, and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  7. Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

    2007-01-01

    Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  8. The coefficient of bond thermal expansion measured by extended x-ray absorption fine structure.

    PubMed

    Fornasini, P; Grisenti, R

    2014-10-28

    The bond thermal expansion is in principle different from the lattice expansion and can be measured by correlation sensitive probes such as extended x-ray absorption fine structure (EXAFS) and diffuse scattering. The temperature dependence of the coefficient α(bond)(T) of bond thermal expansion has been obtained from EXAFS for CdTe and for Cu. A coefficient α(tens)(T) of negative expansion due to tension effects has been calculated from the comparison of bond and lattice expansions. Negative lattice expansion is present in temperature intervals where α(bond) prevails over α(tens); this real-space approach is complementary but not equivalent to the Grüneisen theory. The relevance of taking into account the asymmetry of the nearest-neighbours distribution of distances in order to get reliable bond expansion values and the physical meaning of the third cumulant are thoroughly discussed.

  9. Non-destructive studies of fuel pellets by neutron resonance absorption radiography and thermal neutron radiography

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Vogel, S. C.; Mocko, M.; Bourke, M. A. M.; Yuan, V.; Nelson, R. O.; Brown, D. W.; Feller, W. B.

    2013-09-01

    Many isotopes in nuclear materials exhibit strong peaks in neutron absorption cross sections in the epithermal energy range (1-1000 eV). These peaks (often referred to as resonances) occur at energies specific to particular isotopes, providing a means of isotope identification and concentration measurements. The high penetration of epithermal neutrons through most materials is very useful for studies where samples consist of heavy-Z elements opaque to X-rays and sometimes to thermal neutrons as well. The characterization of nuclear fuel elements in their cladding can benefit from the development of high resolution neutron resonance absorption imaging (NRAI), enabled by recently developed spatially-resolved neutron time-of-flight detectors. In this technique the neutron transmission of the sample is measured as a function of spatial location and of neutron energy. In the region of the spectra that borders the resonance energy for a particular isotope, the reduction in transmission can be used to acquire an image revealing the 2-dimensional distribution of that isotope within the sample. Provided that the energy of each transmitted neutron is measured by the neutron detector used and the irradiated sample possesses neutron absorption resonances, then isotope-specific location maps can be acquired simultaneously for several isotopes. This can be done even in the case where samples are opaque or have very similar transmission for thermal neutrons and X-rays or where only low concentrations of particular isotopes are present (<0.1 atom% in some cases). Ultimately, such radiographs of isotope location can be utilized to measure isotope concentration, and can even be combined to produce three-dimensional distributions using tomographic methods. In this paper we present the proof-of-principle of NRAI and transmission Bragg edge imaging performed at Flight Path 5 (FP5) at the LANSCE pulsed, moderated neutron source of Los Alamos National Laboratory. A set of urania mockup

  10. Photo-thermal nanosystems for diseased cell treatment

    NASA Astrophysics Data System (ADS)

    Raeesi, Vahid

    The prevalence of cancer and infectious disease demands for development of more effective treatment technologies. Current standard chemo- and radiotherapy for cancer offer only relative therapeutic efficacy at the cost of significant side-effects. On the other hand, resistance of microbes to current antibiotics has raised serious concern in public health sectors such as hospitals. Thermal therapy is an alternative technique that employs high temperatures to treat diseased cells via direct and indirect heat effects. Owing to its nature, this technique can offer enhanced therapeutic efficacy in local diseased regions via either mono- or combinatorial platforms and very minimal side-effects. However, existing bulk heating systems are limited in providing selective and controlled temperature rise in the desired region at tissue/cellular scales. This compromises the therapeutic efficacy of the treatment and increases the risk of off-target heating in healthy tissues. In this thesis, we propose the use of heat-generating nanoparticles to precisely target heat into small regions and study how they can be applied in cancer and bacteria treatment. Our model nanoparticle system generates heat by light stimulation. Different nanosystems based on this particle are developed and their thermal effects on therapeutic distribution are explored at tumor tissue and cellular scales. In addition, the thermal effect of these nanoparticles is utilized to overcome microbial resistance. By mechanistic understanding of nanoparticle thermal effects at different length scales, this research helps to rationalize proper design and development of heat- generating nanomedicine for cancer and microbial treatments.

  11. Biodegradation of photo-oxidized lignite and characterization of the products

    NASA Astrophysics Data System (ADS)

    Li, Jiantao; Liu, Xiangrong; Yue, Zilin; Zhang, Yaowen

    2018-01-01

    Biodegradation of photo-oxidized Inner Mongolia lignite by pseudomonas aeruginosa was studied and the degradation percentage reached 56.27%, while the corresponding degradation percentage of the strain degrading raw Inner Mongolia lignite is only 23.16%. The degradation products were characterized. Proximate and ultimate analyses show that the higher oxygen content increased by photo-oxidation pretreatment maybe promoted the degradation process. Ultraviolet spectroscopy (UV) analysis of the liquid product reveals that it contains unsaturated structures and aromatic rings are the main structure units. Gas chromatography-mass spectrometry (GC-MS) analysis indicates that the main components of the ethyl acetate extracts are low molecular weight organic compounds, such as ketones, acids, hydrocarbons, esters and alcohols. Infrared spectroscopy (IR) analysis of raw lignite, photo-oxidized lignite and residual lignite demonstrates that the absorption peaks of functional groups in residual lignite disappeared or weakened obviously. Scanning electron microscopy (SEM) analysis manifests that small holes appear in photo-oxidized lignite surface, which may be promote the degradation process and this is only from the physical morphology aspects, so it can be inferred from the tests and analyses results that the more important reason of the high degradation percentage is mostly that the photo-oxidation pretreatment changes the chemical structures of lignite.

  12. Controls on dissolved organic matter (DOM) degradation in a headwater stream: the influence of photochemical and hydrological conditions in determining light-limitation or substrate-limitation of photo-degradation

    NASA Astrophysics Data System (ADS)

    Cory, R. M.; Harrold, K. H.; Neilson, B. T.; Kling, G. W.

    2015-11-01

    We investigated how absorption of sunlight by chromophoric dissolved organic matter (CDOM) controls the degradation and export of DOM from Imnavait Creek, a beaded stream in the Alaskan Arctic. We measured concentrations of dissolved organic carbon (DOC), as well as concentrations and characteristics of CDOM and fluorescent dissolved organic matter (FDOM), during ice-free periods of 2011-2012 in the pools of Imnavait Creek and in soil waters draining to the creek. Spatial and temporal patterns in CDOM and FDOM in Imnavait Creek were analyzed in conjunction with measures of DOM degradation by sunlight and bacteria and assessments of hydrologic residence times and in situ UV exposure. CDOM was the dominant light attenuating constituent in the UV and visible portion of the solar spectrum, with high attenuation coefficients ranging from 86 ± 12 m-1 at 305 nm to 3 ± 1 m-1 in the photosynthetically active region (PAR). High rates of light absorption and thus light attenuation by CDOM contributed to thermal stratification in the majority of pools in Imnavait Creek under low-flow conditions. In turn, thermal stratification increased the residence time of water and DOM, and resulted in a separation of water masses distinguished by contrasting UV exposure (i.e., UV attenuation by CDOM with depth resulted in bottom waters receiving less UV than surface waters). When the pools in Imnavait Creek were stratified, DOM in the pool bottom water closely resembled soil water DOM in character, while the concentration and character of DOM in surface water was reproduced by experimental photo-degradation of bottom water. These results, in combination with water column rates of DOM degradation by sunlight and bacteria, suggest that photo-degradation is the dominant process controlling DOM fate and export in Imnavait Creek. A conceptual model is presented showing how CDOM amount and lability interact with incident UV light and water residence time to determine whether photo

  13. NOAA Photo Library - Other NOAA Photo Sites

    Science.gov Websites

    National Marine Mammal Laboratory Resource Assessment and Conservation Engineering Fish Photos by Family Florida - Melbourne: Post Storm Damage Surveys and Summaries Florida - Tallahassee: Virtual Office Tour Kentucky - Jackson: Virtual Tour Kentucky - Louisville: Photo Album Kentucky - Paducah: Photo Gallery

  14. Measurement of the Solar Absorptance and Thermal Emittance of Lunar Simulants

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Street, Kenneth W.; Gutafson, Robert J.

    2010-01-01

    The first comparative study of the reflectance spectra of lunar simulants is presented. All of the simulants except one had a wavelength-dependant reflectivity ( ( )) near 0.10 over the wavelength range of 8 to 25 m, so they are highly emitting at room temperature and lower. The 300 K emittance ( ) of all the lunar simulants except one ranged from 0.884 to 0.906. The 300 K of JSC Mars-1 simulant was 0.927. There was considerably more variation in the lunar simulant reflectance in the solar spectral range (250 to 2500 nm) than in the thermal infrared. Larger particle size simulants reflected much less than those with smaller particle size. As expected, the lunar highlands simulants were more reflective in this wavelength range than the lunar mare simulants. The integrated solar absorptance ( ) of the simulants ranged from 0.413 to 0.817 for those with smaller particles, and 0.669 to 0.906 for those with larger particles. Although spectral differences were observed, the for the simulants appears to be similar to that of lunar soils (0.65 to 0.88). These data are now available to be used in modeling the effects of dust on thermal control surfaces.

  15. A new technique to assess dermal absorption of volatile chemicals in vitro by thermal gravimetric analysis.

    PubMed

    Rauma, Matias; Isaksson, Tina S; Johanson, Gunnar

    2006-10-01

    Potential health hazards of dermal exposure, variability in reported dermal absorption rates and potential losses from the skin by evaporation indicate a need for a simple, inexpensive and standardized procedure to measure dermal absorption and desorption of chemical substances. The aim of this study was to explore the possibility to measure dermal absorption and desorption of volatile chemicals using a new gravimetric technique, namely thermal gravimetric analysis (TGA), and trypsinated stratum corneum from pig. Changes in skin weight were readily detected before, during and after exposure to vapours of water, 2-propanol, methanol and toluene. The shape and height of the weight curves differed between the four chemicals, reflecting differences in diffusivity and partial pressure and skin:air partitioning, respectively. As the skin weight is highly sensitive to the partial pressure of volatile chemicals, including water, this technique requires carefully controlled conditions with respect to air flow, temperature, chemical vapour generation and humidity. This new technique may help in the assessment of dermal uptake of volatile chemicals. Only a small piece of skin is needed and skin integrity is not necessary, facilitating the use of human samples. The high resolution weight-time curves obtained may also help to elucidate the characteristics of absorption, desorption and diffusion of chemicals in skin.

  16. Simple system for measuring tritium Ad/absorption using a 2. pi. counter and thermal desorption spectrometer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miyake, H.; Matsuyama, M.; Watanabe, K.

    1992-03-01

    In this paper, the authors develop a simple system using tritium tracer and thermal desorption techniques to measure the tritium adsorption and/or absorption on/in a material having typical surface conditions: namely, not cleaned surface. The tritium counting devices used were a 2{pi} counter and conventional proportional counter. With this system, the amounts of ad/absorption could be measured without exposing the samples to air after exposing them to tritium gas. The overall efficiency (F) of the 2{pi} counter was described at F = exp({minus}2.64h), where h is the distance from the sample to the detector. Ad/absorption measurements were carried out formore » several materials used for fabricating conventional vacuum systems. The results were, in the order of decreasing amounts of ad/absorption, as (fiber reinforced plastics(FRP)) {gt} (nickel(Ni), molybdenum disulfide(MoS{sub 2})) {gt} (stainless steel (SS304), iron(Fe), aluminum alloy(A2219)) {gt} (boron nitride(h-BN), silicon carbide (SiC), SS304 passivated by anodic oxidation layers(ASS) and that by boron nitride segregation layers (BSS)). The relative amounts were abut 100 for Ni and 0.1 for ASS and BSS, being normalized to Fe = 1.« less

  17. Personal Photo Enhancement Using Internet Photo Collections.

    PubMed

    Zhang, Chenxi; Gao, Jizhou; Wang, Oliver; Georgel, Pierre; Yang, Ruigang; Davis, James; Frahm, Jan-Michael; Pollefeys, Marc

    2013-04-26

    Given the growth of Internet photo collections we now have a visual index of all major cities and tourist sites in the world. However, it is still a difficult task to capture that perfect shot with your own camera when visiting these places, especially when your camera itself has limitations, such as a limited field of view. In this paper, we propose a framework to overcome the imperfections of personal photos of tourist sites using the rich information provided by large scale Internet photo collections. Our method deploys state-of-the-art techniques for constructing initial 3D models from photo collections. The same techniques are then used to register personal photos to these models, allowing us to augment personal 2D images with 3D information. This strong available scene prior allows us to address a number of traditionally challenging image enhancement techniques, and achieve high quality results using simple and robust algorithms. Specifically, we demonstrate automatic foreground segmentation, mono-to-stereo conversion, the field of view expansion, photometric enhancement, and additionally automatic annotation with geo-location and tags. Our method clearly demonstrates some possible benefits of employing the rich information contained in on-line photo databases to efficiently enhance and augment one’s own personal photos.

  18. Kinetics of thermal and photo-initiated release of tris (1,3-dichloro-2-propyl) phosphate (TDCP) flame retardant from polyurethane foam materials.

    PubMed

    Ghanem, Raed A

    2015-01-01

    Kinetics of thermal and photo-initiated release of Tris (1.3-dichloro-2-propyl) phosphate (TDCP) from the polyurethane foam (PUF) materials were studied using a validated chromatographic method with linear calibration curve in the range of 0.03-400 μg mL(-1). Time dependence of TDCP leaching from foam samples was found to follow first-order kinetics; with rate constants directly dependent on ageing temperatures and intensity of UV radiation, rate constants for the thermally and photo initiated were 3.6 × 10(-3), 1.03 × 10(-2), 3.6 × 10(-2) and 3.94 × 10(-2) day(-1), respectively. Migration of TDCP from foam samples simulating skin or oral exposure were observed from all samples regardless of their ageing history, the presence of biological fluids found to enhance the migration rate. Oral exposure to foam material contains TDCP, which was simulated using the Head-over-Heels test, reveals that an average amount of ∼ 1.7% wt./wt. of the total amount of TDCP was found to leach into biological fluids, and it significantly increased to ∼ 6.0% wt./wt. due to ageing conditions. Direct contact between foam material and skin simulated by using the Contact Blotting test reveals that TDCP is transferred from both aged and un-aged samples at different rates, due to the presence of biological fluids; the transferred amount is increased with ageing conditions.

  19. Thermal expansion behavior study of Co nanowire array with in situ x-ray diffraction and x-ray absorption fine structure techniques

    NASA Astrophysics Data System (ADS)

    Mo, Guang; Cai, Quan; Jiang, Longsheng; Wang, Wei; Zhang, Kunhao; Cheng, Weidong; Xing, Xueqing; Chen, Zhongjun; Wu, Zhonghua

    2008-10-01

    In situ x-ray diffraction and x-ray absorption fine structure techniques were used to study the structural change of ordered Co nanowire array with temperature. The results show that the Co nanowires are polycrystalline with hexagonal close packed structure without phase change up until 700 °C. A nonlinear thermal expansion behavior has been found and can be well described by a quadratic equation with the first-order thermal expansion coefficient of 4.3×10-6/°C and the second-order thermal expansion coefficient of 5.9×10-9/°C. The mechanism of this nonlinear thermal expansion behavior is discussed.

  20. Seasonal Solar Thermal Absorption Energy Storage Development.

    PubMed

    Daguenet-Frick, Xavier; Gantenbein, Paul; Rommel, Mathias; Fumey, Benjamin; Weber, Robert; Gooneseker, Kanishka; Williamson, Tommy

    2015-01-01

    This article describes a thermochemical seasonal storage with emphasis on the development of a reaction zone for an absorption/desorption unit. The heat and mass exchanges are modelled and the design of a suitable reaction zone is explained. A tube bundle concept is retained for the heat and mass exchangers and the units are manufactured and commissioned. Furthermore, experimental results of both absorption and desorption processes are presented and the exchanged power is compared to the results of the simulations.

  1. Photo-thermal reactions of ethanol over Ag/TiO2 catalysts. The role of silver plasmon resonance in the reaction kinetics.

    PubMed

    Nadeem, M A; Idriss, H

    2018-05-17

    Photo-thermal catalytic reactions of ethanol over Ag/TiO2 were conducted in order to probe into the role of plasmonic resonance response in the reaction kinetics. In the 300-500 K temperature domain the increase in reaction rate is found to be mainly due to changes in the activation energy while above this temperature range the increase was due to the pre-exponential factor. These results might be linked to the role of plasmonic Ag particles in polarising the reaction intermediates and therefore increasing the reaction products at temperatures up to about 500 K.

  2. Effect of different photo-initiators and light curing units on degree of conversion of composites.

    PubMed

    Brandt, William Cunha; Schneider, Luis Felipe Jochims; Frollini, Elisabete; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho

    2010-01-01

    The aim of this study was to evaluate: (i) the absorption of photo-initiators and emission spectra of light curing units (LCUs); and (ii) the degree of conversion (DC) of experimental composites formulated with different photo-initiators when activated by different LCUs. Blends of BisGMA, UDMA, BisEMA and TEGDMA with camphorquinone (CQ) and/ or 1-phenyl-1,2-propanedione (PPD) were prepared. Dimethylaminoethyl methacrylate (DMAEMA) was used as co-initiator. Each mixture was loaded with 65 wt% of silanated filler particles. One quartz-tungsten-halogen - QTH (XL 2500, 3M/ESPE) and two lightemitting diode (LED) LCUs (UltraBlue IS, DMC and UltraLume LED 5, Ultradent) were used for activation procedures. Irradiance (mW/cm²) was calculated by the ratio of the output power by the area of the tip, and spectral distribution with a spectrometer (USB 2000). The absorption curve of each photo-initiator was determined using a spectrophotometer (Varian Cary 5G). DC was assessed by Fourier transformed infrared spectroscopy. Data were submitted to two-way ANOVA and Tukey's test (5%). No significant difference was found for DC values when using LED LCUs regardless of the photo-initiator type. However, PPD showed significantly lower DC values than composites with CQ when irradiated with QTH. PPD produced DC values similar to those of CQ, but it was dependent on the LCU type.

  3. Exploitation of knowledge databases in the synthesis of zinc(II) malonates with photo-sensitive and photo-insensitive N,N'-containing linkers.

    PubMed

    Zorina-Tikhonova, Ekaterina N; Chistyakov, Aleksandr S; Kiskin, Mikhail A; Sidorov, Aleksei A; Dorovatovskii, Pavel V; Zubavichus, Yan V; Voronova, Eugenia D; Godovikov, Ivan A; Korlyukov, Alexander A; Eremenko, Igor L; Vologzhanina, Anna V

    2018-05-01

    Photoinitiated solid-state reactions are known to affect the physical properties of coordination polymers, such as fluorescence and sorption behaviour, and also afford extraordinary architectures ( e.g. three-periodic structures with polyorganic ligands). However, the construction of novel photo-sensitive coordination polymers requires an understanding of the factors which govern the mutual disposition of reactive fragments. A series of zinc(II) malonate complexes with 1,2-bis(pyridin-4-yl)ethylene and its photo-insensitive analogues has been synthesized for the purpose of systematic analysis of their underlying nets and mutual disposition of N -donor ligands. The application of a big data-set analysis for the prediction of a variety of possible complex compositions, coordination environments and networks for a four-component system has been demonstrated for the first time. Seven of the nine compounds possess one of the highly probable topologies for their underlying nets; in addition, two novel closely related four-coordinated networks were obtained. Complexes containing 1,2-bis(pyridin-4-yl)ethylene and 1,2-bis(pyridin-4-yl)ethane form isoreticular compounds more readily than those with 4,4'-bipyridine and 1,2-bis(pyridin-4-yl)ethylene. The effects of the precursor, either zinc(II) nitrate or zinc(II) acetate, on the composition and dimensionality of the resulting architecture are discussed. For three of the four novel complexes containing 1,2-bis(pyridin-4-yl)ethylene, the single-crystal-to-single-crystal [2 + 2] cycloaddition reactions were carried out. UV irradiation of these crystals afforded either the 0D→1D or the 3D→3D transformations, with and without network changes. One of the two 3D→3D transformations was accompanied by solvent (H 2 O) cleavage.

  4. Real time spectrometer for thermal neutrons from radiotherapic accelerators

    NASA Astrophysics Data System (ADS)

    Mozzanica, A.; Bartesaghi, G.; Bolognini, D.; Conti, V.; Mascagna, V.; Prest, M.; Scazzi, S.; Cappelletti, P.; Frigerio, M.; Gelosa, S.; Monti, A.; Ostinelli, A.; Bevilacqua, R.; Giannini, G.; Totaro, P.; Vallazza, E.

    2007-10-01

    Radiotherapy accelerators can produce high energy photon beams for deep tumour treatments. Photons with energies greater than 8 MeV produce neutrons via photoproduction. The PHONES (PHOto NEutron Source) project is developing a neutron moderator to use the photoproduced neutrons for BNCT (Boron Neutron Capture Therapy) in hospital environments. In this framework we are developing a real time spectrometer for thermal neutrons exploiting the bunch structure of the beam. Since the beam is produced by a linear accelerator, in fact, particles are sent to the patient in bunches with a rate of 150-300 Hz depending on the beam type and energy. The neutron spectrum is usually measured with integrating detectors such as bubble dosimeters or TLDs, which integrate over a time interval and an energy one. We are developing a scintillator detector to measure the neutron spectrum in real time in the interval between bunches, that is in the thermal region. The signals from the scintillator are discriminated and sampled by a dedicated clock in a Cyclone II FPGA by Altera, thus obtaining the neutron time of flight spectrum. The exploited physical process in ordinary plastic scintillators is neutron capture by H with a subsequent γ emission. The measured TOF spectrum has been compared with a BF 3 counter one. A dedicated simulation with MCNP is being developed to extract the energy spectrum from the TOF one. The paper will present the results of the prototype measurements and the status of the simulation.

  5. Absorption and emission spectroscopic characterisation of combined wildtype LOV1-LOV2 domain of phot from Chlamydomonas reinhardtii.

    PubMed

    Song, S-H; Dick, B; Zirak, P; Penzkofer, A; Schiereis, T; Hegemann, P

    2005-10-03

    An absorption and emission spectroscopic characterisation of the combined wild-type LOV1-LOV2 domain string (abbreviated LOV1/2) of phot from the green alga Chlamydomonas reinhardtii is carried out at pH 8. A LOV1/2-MBP fusion protein (MBP=maltose binding protein) and LOV1/2 with a His-tag at the C-terminus (LOV1/2-His) expressed in an Escherichia coli strain are investigated. Blue-light photo-excitation generates a non-fluorescent intermediate photoproduct (flavin-C(4a)-cysteinyl adduct with absorption peak at 390 nm). The photo-cycle dynamics is studied by dark-state absorption and fluorescence measurement, by following the temporal absorption and emission changes under blue and violet light exposure, and by measuring the temporal absorption and fluorescence recovery after light exposure. The fluorescence quantum yield, phi(F), of the dark adapted samples is phi(F)(LOV1/2-His) approximately 0.15 and phi(F)(LOV1/2-MBP) approximately 0.17. A bi-exponential absorption recovery after light exposure with a fast (in the several 10-s range) and a slow component (in the near 10-min range) are resolved. The quantum yield of photo-adduct formation, phi(Ad), is extracted from excitation intensity dependent absorption measurements. It decreases somewhat with rising excitation intensity. The behaviour of the combined wildtype LOV1-LOV2 double domains is compared with the behaviour of the separate LOV1 and LOV2 domains.

  6. Inverse Modeling of the Thermal Hydrodynamic and Chemical Processes During Exploitation of the Mutnovsky Geothermal Field (Kamchatka, Russia)

    NASA Astrophysics Data System (ADS)

    Kiryukhin, A. V.

    2012-12-01

    A TOUGH2-EOS1 3D rectangular numerical model of the Mutnovsky geothermal field (Kiryukhin, 1996) was re-calibrated using natural state and history exploitation data during the time period 1984-2006 years. Recalibration using iTOUGH2-EOS1+tracer inversion modeling capabilities, was useful to remove outliers from calibration data, identify sets of the estimated parameters of the model, and perform estimations. Chloride ion was used as a "tracer" in this modeling. Thermal hydrodynamic observational data which were used for model recalibration are as follows: 37 temperature and 1 pressure calibration points - for natural state, 13 production wells with monthly averaged enthalpies (650 values during the time period 1983-1987, 2000-2006 years) and 1 transient pressure monitoring wells (57 values during 2003-2006 years) - for exploitation history match. Chemical observational data includes transient mass chloride concentrations from 10 production wells and chloride hot spring sampling data (149 values during 1999-2006 years). The following features of Mutnovsky geothermal reservoir based on integrated inverse modeling analysis of natural state and exploitation data were estimated and better understood: 1. Reservoir permeability was found to be one order more comparable to model-1996, especially the lower part coinciding with intrusion contact zone (600-800 mD at -750 - -1250 masl); 2. Local meteoric inflow in the central part of the field accounting for 45 - 80 kg/s since year 2002; 3. Reinjection rates were estimated significantly lower, than officially reported as 100% of total fluid withdrawal; 4. Upflow fluid flows were estimated hotter (314oC) and the rates are larger (+50%), than assumed before; 5. Global double porosity parameters estimates are: fracture spacing - 5 - 10 m, void fraction N 10-3; 6. Main upflow zone chloride mass concentration estimate is 150 ppm. Conversion of the calibrated TOUGH2-EOS1+tracer model into electrical resistivity model using TOUGH2

  7. Photo-induced optical activity in phase-change memory materials.

    PubMed

    Borisenko, Konstantin B; Shanmugam, Janaki; Williams, Benjamin A O; Ewart, Paul; Gholipour, Behrad; Hewak, Daniel W; Hussain, Rohanah; Jávorfi, Tamás; Siligardi, Giuliano; Kirkland, Angus I

    2015-03-05

    We demonstrate that optical activity in amorphous isotropic thin films of pure Ge2Sb2Te5 and N-doped Ge2Sb2Te5N phase-change memory materials can be induced using rapid photo crystallisation with circularly polarised laser light. The new anisotropic phase transition has been confirmed by circular dichroism measurements. This opens up the possibility of controlled induction of optical activity at the nanosecond time scale for exploitation in a new generation of high-density optical memory, fast chiroptical switches and chiral metamaterials.

  8. Investigation of polypyrrole/polyvinyl alcohol-titanium dioxide composite films for photo-catalytic applications

    NASA Astrophysics Data System (ADS)

    Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long; Dan, Yi

    2015-07-01

    Polypyrrole/polyvinyl alcohol-titanium dioxide (PPy/PVA-TiO2) composite films used as photo-catalysts were fabricated by combining TiO2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet-vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA-TiO2 composite films show better photo-catalytic properties than TiO2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA-TiO2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

  9. Low absorptance porcelain-on-aluminum coating

    NASA Technical Reports Server (NTRS)

    Leggett, H.

    1979-01-01

    Porcelain thermal-control coating for aluminum sheet and foil has solar absorptance of 0.22. Specially formulated coating absorptance is highly stable, changing only 0.03 after 1,000 hours of exposure to simulated sunlight and can be applied by standard commercial methods.

  10. Silicon based mechanic-photonic wavelength converter for infrared photo-detection

    NASA Astrophysics Data System (ADS)

    Rudnitsky, Arkady; Agdarov, Sergey; Gulitsky, Konstantin; Zalevsky, Zeev

    2017-06-01

    In this paper we present a new concept to realize a mechanic-photonic wavelength converter in silicon chip by construction of nanorods and by modulating the input illumination at temporal frequency matched to the mechanic resonance of the nanorods. The use case is to realize an infrared photo detector in silicon which is not based on absorption but rather on the mechanical interaction of the nanorods with the incoming illumination.

  11. Structural, thermal and optical absorption features of heavy metal oxides doped tellurite rich glasses

    NASA Astrophysics Data System (ADS)

    Kaky, Kawa M.; Lakshminarayana, G.; Baki, S. O.; Kityk, I. V.; Taufiq-Yap, Y. H.; Mahdi, M. A.

    In order to improve tellurite glass stability to be applicable for optical fiber amplifier applications, glasses with the composition of (70 - x)TeO2. (10)ZnO. (10)WO3. (5)Na2O. (5)TiO2. (x)Bi2O3 (x = 1, 2, 3, 4, and 5 mol%) have been produced and characterized using the related methods. Structural properties were investigated using X-ray diffraction (XRD) which confirms the non-crystalline structure and scanning electron microscopy (SEM) micrographs also confirm the XRD results. The energy dispersive X-ray (EDX) analysis profiles show that all the mentioned elements are present in the prepared glasses. Following the IR spectra, all the tellurium bonds such as stretching vibrations of TeO4 tbp and TeO3/TeO3+1 unit are revealed. Raman spectra confirm the presence of different functional groups, actually, it shows bands mainly in four spectral regions: R1 (65-150) cm-1, R2 (280-550) cm-1, R3 (880-950) cm-1 and R4 (916-926) cm-1 and the identified bands are assigned to respective molecular groups. The thermal study was carried out using Differential scanning calorimetry (DSC) which indicates good thermal stability of the synthesized glasses with increasing Bi concentration. From the optical absorption spectra, we evaluated cut-off edge wavelengths and found increasing cutoff wavelength with an increase in Bi2O3 concentration. In the UV-Visible region, optical band gap energy and allowed transitions were investigated using three methods; direct, indirect, and absorption spectrum fitting (ASF), and band gaps from indirect and ASF were matched.

  12. Influence of TiO2 hollow sphere size on its photo-reduction activity for toxic Cr(VI) removal.

    PubMed

    Cai, Jiabai; Wu, Xueqing; Zheng, Fengying; Li, Shunxing; Wu, Yaling; Lin, Yanping; Lin, Liting; Liu, Biwen; Chen, Qiaoying; Lin, Luxiu

    2017-03-15

    After polystyrene@titanium dioxide (PS@TiO 2 ) composite with different size was calcined at designated temperature, TiO 2 hollow sphere with controllable size was obtained for high efficient photo-reduction of Cr(VI). The feature of the TiO 2 hollow sphere was investigated by SEM, TEM, XRD, UV-Vis, and photoluminescence. The photo-reduction of Cr(VI) were measured for the performance assessment of the TiO 2 hollow sphere, Cr(VI) was used as an electron acceptor. After irradiation for 2h, the photo-reduction rate of Cr(VI) (pH=2.82) for TiO 2 (450nm) was 96%, which exhibited an increase of 5% and 8% compared with TiO 2 (370nm) and TiO 2 (600nm). The absorption edges of TiO 2 hollow sphere (450nm) was largest with the increasing of hollow sphere size from 370 to 600nm. The optimal hollow sphere size of TiO 2 was 450nm for the photo-reduction of Cr(VI), because the light-harvesting efficiency (the best of absorption edge) and photo-generated electron-hole separation rate (the best of photo-reduction rate) of TiO 2 hollow sphere were controlled by its hollow sphere size. In addition, we find that the behavior of the hydrogen production was inhibited by the coexistence Cr(VI) solution. This study can improve our understanding of the mechanism for the activity enhancement by the optimal hollow sphere size of TiO 2 . Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  14. Automatic land cover classification of geo-tagged field photos using deep learning method

    NASA Astrophysics Data System (ADS)

    Xu, G.; Zhu, X.; Fu, D.; Dong, J.; Xiao, X.

    2016-12-01

    With the popularity of smartphones, more and more crowdsourcing geo-tagged field photos have been shared by the public online. They are becoming a potentially valuable information source for the environmental studies. However, the labelling and recognition of these photos are time-consuming. To utilise and exploit such information, this research aims to propose a land cover type recognition model for geo-tagged field photo based on the deep learning technique. This model combines a pre-trained convolutional neural network (CNN) as the image feature extractor and the softmax regression model as the feature classifier. The pre-trained CNN model Inception-v3 is used in this study. The previously labelled field photos from the Global Geo-Referenced Field Photo Library (http://eomf.ou.edu/photos) are chosen for model training and validation. The results indicate that our field photo recognition model achieves an acceptable accuracy (50.34% for top-1 prediction and 78.20% for top-3 prediction) of land cover classification. What is more important, this model can provide the probabilities for the predictions as the self-assessment of uncertainty. After filtering out the predictions with the certainty of less than 75%, the overall accuracy can increase to 80.14%, which implies that the model is fully aware of its prediction uncertainty and can quantitatively assess it. Hopefully, by proving the possibility of this type of research, other similar studies could be further conducted, such as geological and atmospheric information extraction from field photos. This research could be a critical exploration of how artificial intelligence and crowd-sourced data can help the earth studies.

  15. Photo plot bias.

    Treesearch

    Robert B. Pope; Bijan Payandeh; David R. Paine

    1972-01-01

    The photo intensity, or number of aerial photos per unit of land surface, was examined for six Agricultural Stabilization and Conservation Service photo projects in western Oregon and Washington. On each of the six projects, lands that were primarily nonforest were found to have more photos per unit of area than did the forest lands. Overall, photo intensity averaged 4...

  16. Three-Dimensional Flow of an Oldroyd-B Fluid with Variable Thermal Conductivity and Heat Generation/Absorption

    PubMed Central

    Shehzad, Sabir Ali; Alsaedi, Ahmed; Hayat, Tasawar; Alhuthali, M. Shahab

    2013-01-01

    This paper looks at the series solutions of three dimensional boundary layer flow. An Oldroyd-B fluid with variable thermal conductivity is considered. The flow is induced due to stretching of a surface. Analysis has been carried out in the presence of heat generation/absorption. Homotopy analysis is implemented in developing the series solutions to the governing flow and energy equations. Graphs are presented and discussed for various parameters of interest. Comparison of present study with the existing limiting solution is shown and examined. PMID:24223780

  17. Tetanus (Lockjaw) Photos

    MedlinePlus

    ... be unsuitable for children. Viewing discretion is advised. Photos of the Disease and Images of People Affected by the Disease This micrograph ... Photo ID# 2857 PHIL Photo ID# 1657 PHIL Photo ID# 6373 Additional Images and Regulations Be sure to see the regulations ...

  18. Universal modal radiation laws for all thermal emitters

    PubMed Central

    Zhu, Linxiao; Fan, Shanhui

    2017-01-01

    We derive four laws relating the absorptivity and emissivity of thermal emitters. Unlike the original Kirchhoff radiation law derivations, these derivations include diffraction, and so are valid also for small objects, and can also cover nonreciprocal objects. The proofs exploit two recent approaches. First, we express all fields in terms of the mode-converter basis sets of beams; these sets, which can be uniquely established for any linear optical object, give orthogonal input beams that are coupled one-by-one to orthogonal output beams. Second, we consider thought experiments using universal linear optical machines, which allow us to couple appropriate beams and black bodies. Two of these laws can be regarded as rigorous extensions of previously known laws: One gives a modal version of a radiation law for reciprocal objects—the absorptivity of any input beam equals the emissivity into the “backward” (i.e., phase-conjugated) version of that beam; another gives the overall equality of the sums of the emissivities and the absorptivities for any object, including nonreciprocal ones. The other two laws, valid for reciprocal and nonreciprocal objects, are quite different from previous relations. One shows universal equivalence of the absorptivity of each mode-converter input beam and the emissivity into its corresponding scattered output beam. The other gives unexpected equivalences of absorptivity and emissivity for broad classes of beams. Additionally, we prove these orthogonal mode-converter sets of input and output beams are the ones that maximize absorptivities and emissivities, respectively, giving these beams surprising additional physical meaning. PMID:28396436

  19. Absorption and fluorescence spectroscopic characterisation of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry)

    NASA Astrophysics Data System (ADS)

    Shirdel, J.; Zirak, P.; Penzkofer, A.; Breitkreuz, H.; Wolf, E.

    2008-09-01

    The absorption and fluorescence behaviour of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry) in a pH 8 aqueous buffer solution is studied. The flavin adenine dinucleotide (FAD) cofactor of dCry is identified to be present in its oxidized form (FAD ox), and the 5,10-methenyltetrahydrofolate (MTHF) cofactor is found to be hydrolyzed and oxidized to 10-formyldihydrofolate (10-FDHF). The absorption and the fluorescence behaviour of dCry is investigated in the dark-adapted (receptor) state, the light-adapted (signalling) state, and under long-time violet light exposure. Photo-excitation of FAD ox in dCry causes a reductive electron transfer to the formation of anionic FAD semiquinone (FAD rad - ), and photo-excitation of the generated FAD rad - causes an oxidative electron transfer to the back formation of FAD ox. In light adapted dCry a photo-induced equilibrium between FAD ox and FAD rad - exists. The photo-cycle dynamics of signalling state formation and recovery is discussed. Quantum yields of photo-induced signalling state formation of about 0.2 and of photo-induced back-conversion of about 0.2 are determined. A recovery of FAD rad - to FAD ox in the dark with a time constant of 1.6 min at room temperature is found.

  20. Exploiting absorption-induced self-heating in solar cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ullbrich, Sascha; Fischer, Axel; Erdenebileg, Enkhtur; Koerner, Christian; Reineke, Sebastian; Leo, Karl; Vandewal, Koen

    2017-04-01

    Absorption of light inevitably leads to a self-heating of each type of solar cell, either due to the excess energy of absorbed photons or non-radiative recombination of charge carriers. Although the effect of temperature on solar cell parameters such as the open-circuit voltage are well known, it is often ignored in Suns-Voc measurements [1]. This measurement technique enables direct access to the diode ideality factor without an influence by series resistance. A frequently seen decrease of the ideality factor or a saturation of the open-circuit voltage at high illumination intensities is often attributed solely to surface recombination [2], the shape of the density of states (DOS) [3], or the quality of the back contact in inorganic solar cells [4]. In this work, we present an analytical model for taking into account absorption induced self-heating in Suns-Voc measurements and validate it for various solar cell technologies such as small molecule organic solar cells, perovskite solar cells, and inorganic solar cells. Furthermore, with an adapted Suns-Voc technique, we are able to not only correctly determine the ideality factor, but also the relevant energy gap of the solar cell, which is especially of interest in the field of novel solar cell technologies. [1] R.A. Sinton and A. Cuevas, EU PVSEC, 1152-1155 (2000) [2] K. Tvingstedt and C. Deibel, Adv. Energy Mater. 6, 1502230 (2016) [3] T. Kirchartz and J. Nelson, Phys. Rev. B 86, 165201 (2012) [4] S. Glunz, J. Nekarda, H. Maeckel et al., EU PVSEC, 849-853 (2007)

  1. Optical planar waveguides in photo-thermal-refractive glasses fabricated by single- or double-energy carbon ion implantation

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Shen, Xiao-Liang; Zheng, Rui-Lin; Guo, Hai-Tao; Lv, Peng; Liu, Chun-Xiao

    2018-01-01

    Ion implantation has demonstrated to be an efficient and reliable technique for the fabrication of optical waveguides in a diversity of transparent materials. Photo-thermal-refractive glass (PTR) is considered to be durable and stable holographic recording medium. Optical planar waveguide structures in the PTR glasses were formed, for the first time to our knowledge, by the C3+-ion implantation with single-energy (6.0 MeV) and double-energy (5.5+6.0 MeV), respectively. The process of the carbon ion implantation was simulated by the stopping and range of ions in matter code. The morphologies of the waveguides were recorded by a microscope operating in transmission mode. The guided beam distributions of the waveguides were measured by the end-face coupling technique. Comparing with the single-energy implantation, the double-energy implantation improves the light confinement for the dark-mode spectrum. The guiding properties suggest that the carbon-implanted PTR glass waveguides have potential for the manufacture of photonic devices.

  2. Evidence for photo-induced monoclinic metallic VO{sub 2} under high pressure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hsieh, Wen-Pin, E-mail: wphsieh@stanford.edu; Mao, Wendy L.; Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305

    2014-01-13

    We combine ultrafast pump-probe spectroscopy with a diamond-anvil cell to decouple the insulator-metal electronic transition from the lattice symmetry changing structural transition in the archetypal strongly correlated material vanadium dioxide. Coherent phonon spectroscopy enables tracking of the photo-excited phonon vibrational frequencies of the low temperature, monoclinic (M{sub 1})-insulating phase that transforms into the metallic, tetragonal rutile structured phase at high temperature or via non-thermal photo-excitations. We find that in contrast with ambient pressure experiments where strong photo-excitation promptly induces the electronic transition along with changes in the lattice symmetry, at high pressure, the coherent phonons of the monoclinic (M{sub 1})more » phase are still clearly observed upon the photo-driven phase transition to a metallic state. These results demonstrate the possibility of synthesizing and studying transient phases under extreme conditions.« less

  3. Power Electronics Thermal Management | Transportation Research | NREL

    Science.gov Websites

    Power Electronics Thermal Management Power Electronics Thermal Management A photo of water boiling in liquid cooling lab equipment. Power electronics thermal management research aims to help lower the investigates and develops thermal management strategies for power electronics systems that use wide-bandgap

  4. Energy Storage Thermal Performance | Transportation Research | NREL

    Science.gov Websites

    Thermal Performance Energy Storage Thermal Performance Photo of tweezers placing a small round nation's recognized leader in battery thermal management research and development (R&D), NREL is one of system level. The lab's assessments of thermal behavior, capacity, lifespan, and overall performance

  5. Research of waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Zhang, Yu; Zhou, Liansheng; E, Zhijun; Wang, Kun; Wang, Ziyue; Li, Guohao; Qu, Bin

    2018-02-01

    The waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water has been analyzed. After the operation of heat pump, the influences on power generation and heat generation of unit were taken into account. In the light of the characteristics of heat pump in different operation stages, the energy efficiency of heat pump was evaluated comprehensively on both sides of benefits belonging to electricity and benefits belonging to heat, which adopted the method of contrast test. Thus, the reference of energy efficiency for same type projects was provided.

  6. Characterization of photo-induced valence tautomerism in a cobalt-dioxolene complex by ultrafast spectroscopy

    NASA Astrophysics Data System (ADS)

    Beni, A.; Bogani, L.; Bussotti, L.; Dei, A.; Gentili, P. L.; Righini, R.

    2005-01-01

    The valence tautomerism of low-spin CoIII(Cat-N-BQ)(Cat-N-SQ) was investigated by means of UV-vis pump-probe transient absorption spectroscopy in chloroform. By exciting the CT transition of the complex at 480 nm, an intramolecular electron transfer process is selectively triggered. The photo-induced charge transfer is pursued by a cascade of two main molecular events characterized by the ultrafast transient absorption spectroscopy: the first gives rise to the metastable high-spin CoII(Cat-N-BQ)2 that, secondly, reaches the chemical equilibrium with the reactant species.

  7. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image , Enid Photo Date: June 5, 1966 Photographer: Leo Ainsworth Credit: NOAA Photo Library, NOAA Central

  8. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Location: Oklahoma, Altus Photo Date: May 20, 1977 Photographer: D. Burgess Credit: NOAA Photo Library

  9. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Location: Oklahoma, Arcadia Photo Date: June 8, 1974 Photographer: D. Burgess Credit: NOAA Photo Library

  10. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Location: SW of Cheyenne, Oklahoma Photo Date: May 16, 1977 Credit: NOAA Photo Library, NOAA Central

  11. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image ) Collection Location: Texas, Wichita Falls Photo Date: April 10, 1979 Credit: NOAA Photo Library, NOAA Central

  12. Control over photo-inscription and thermal annealing to obtain high-quality Bragg gratings in doped PMMA optical fibers.

    PubMed

    Hu, Xuehao; Kinet, Damien; Mégret, Patrice; Caucheteur, Christophe

    2016-07-01

    Bragg gratings are photo-inscribed in trans-4-stilbenemethanol doped PMMA fibers using a 325 nm He-Cd laser and a phase mask. Two distinct behaviors are reported depending on the laser power density. In the high-density regime with 637  mW/mm2, the grating reflectivity is stable over time after the writing process, but the reflected spectrum is of limited quality, as the grating length is limited to the laser width (1.2 mm). The beam is then enlarged to 6 mm, decreasing the power density to 127  mW/mm2. In this case, the grating reflectivity strongly decays after the writing process. A fortunate property here results from the recovery of the initial reflectivity using a post-inscription thermal annealing. Both behaviors are attributed to the evolution between trans- and cis-isomers.

  13. Photo-responsive polymeric micelles.

    PubMed

    Huang, Yu; Dong, Ruijiao; Zhu, Xinyuan; Yan, Deyue

    2014-09-07

    Photo-responsive polymeric micelles have received increasing attention in both academic and industrial fields due to their efficient photo-sensitive nature and unique nanostructure. In view of the photo-reaction mechanism, photo-responsive polymeric micelles can be divided into five major types: (1) photoisomerization polymeric micelles, (2) photo-induced rearrangement polymeric micelles, (3) photocleavage polymeric micelles, (4) photo-induced crosslinkable polymeric micelles, and (5) photo-induced energy conversion polymeric micelles. This review highlights the recent advances of photo-responsive polymeric micelles, including the design, synthesis and applications in various biomedical fields. Especially, the influence of different photo-reaction mechanisms on the morphology, structure and properties of the polymeric micelles is emphasized. Finally, the possible future directions and perspectives in this emerging area are briefly discussed.

  14. Thermal Distribution System | Energy Systems Integration Facility | NREL

    Science.gov Websites

    Thermal Distribution System Thermal Distribution System The Energy Systems Integration Facility's integrated thermal distribution system consists of a thermal water loop connected to a research boiler and . Photo of the roof of the Energy Systems Integration Facility. The thermal distribution bus allows

  15. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Location: Near Shamrock, Texas Photo Date: May 16, 1977 Credit: NOAA Photo Library, NOAA Central Library

  16. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Location: Union City, Oklahoma Photo Date: May 24, 1973 Credit: NOAA Photo Library, NOAA Central Library

  17. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Location: Near Mayfield, Oklahoma Photo Date: May 16, 1977 Credit: NOAA Photo Library, NOAA Central Library

  18. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Location: Near Lakeview, Texas Photo Date: April 19, 1977 Credit: NOAA Photo Library, NOAA Central Library

  19. Sensitive photo-thermal response of graphene oxide for mid-infrared detection

    NASA Astrophysics Data System (ADS)

    Bae, Jung Jun; Yoon, Jung Hyun; Jeong, Sooyeon; Moon, Byoung Hee; Han, Joong Tark; Jeong, Hee Jin; Lee, Geon-Woong; Hwang, Ha Ryong; Lee, Young Hee; Jeong, Seung Yol; Lim, Seong Chu

    2015-09-01

    This study characterizes the effects of incident infrared (IR) radiation on the electrical conductivity of graphene oxide (GO) and examines its potential for mid-IR detection. Analysis of the mildly reduced GO (m-GO) transport mechanism near room temperature reveals variable range hopping (VRH) for the conduction of electrons. This VRH behavior causes the m-GO resistance to exhibit a strong temperature dependence, with a large negative temperature coefficient of resistance of approximately -2 to -4% K-1. In addition to this hopping transport, the presence of various oxygen-related functional groups within GO enhances the absorption of IR radiation significantly. These two GO material properties are synergically coupled and provoke a remarkable photothermal effect within this material; specifically, a large resistance drop is exhibited by m-GO in response to the increase in temperature caused by the IR absorption. The m-GO bolometer effect identified in this study is different from that exhibited in vanadium oxides, which require added gold-black films that function as IR absorbers owing to their limited IR absorption capability.This study characterizes the effects of incident infrared (IR) radiation on the electrical conductivity of graphene oxide (GO) and examines its potential for mid-IR detection. Analysis of the mildly reduced GO (m-GO) transport mechanism near room temperature reveals variable range hopping (VRH) for the conduction of electrons. This VRH behavior causes the m-GO resistance to exhibit a strong temperature dependence, with a large negative temperature coefficient of resistance of approximately -2 to -4% K-1. In addition to this hopping transport, the presence of various oxygen-related functional groups within GO enhances the absorption of IR radiation significantly. These two GO material properties are synergically coupled and provoke a remarkable photothermal effect within this material; specifically, a large resistance drop is exhibited by m

  20. Dispersive bi-stability in a vertical microcavity-based saturable absorber due to photo-thermal effect and initial phase-detuning

    NASA Astrophysics Data System (ADS)

    Pradhan, R.; Saha, S.; Datta, P. K.

    2013-01-01

    Round-trip phase-shifts with intensity of an input signal due to saturable index change and optically induced thermal effects in a vertical cavity semiconductor (quantum wells) saturable absorber (VCSSA) are investigated analytically to observe counter-clockwise bi-stability in transmission mode and clockwise bi-stability in reflection mode. Simultaneous effects of Kerr nonlinearity and cavity heating on resonance wavelength-shift of the VCSSA micro-cavity are investigated. It is found that these bi-stable characteristics are possible to the absorption edge of nonlinear material for long wavelength side operations of low intensity resonance wavelength of the micro-cavity, where dispersion of absorption and refraction are neglected over a small range of optical wavelength tuning (δλ˜10 nm). Simulations are carried out to find out optimized parameters of the device for bi-stable characteristics. Operations are demonstrated for InGaAs/InP quantum wells based VCSSA with low intensity resonance wavelength of 1570 nm. For counter-clockwise bi-stable switching at working wavelength of 1581 nm, an input intensity variation of 0.79IS is required with top (Rt) and back DBR reflectivity (Rb) of 91% and 93%, respectively, where IS represents the absorption saturation intensity of nonlinear medium. Whereas, the clockwise bi-stability occurs at 0.22IS for working wavelength of 1578 nm with Rt of 90% and Rb of 98%, respectively.

  1. Characterizing phantom arteries with multi-channel laser ultrasonics and photo-acoustics.

    PubMed

    Johnson, Jami L; van Wijk, Kasper; Sabick, Michelle

    2014-03-01

    Multi-channel photo-acoustic and laser ultrasonic waves are used to sense the characteristics of proxies for healthy and diseased vessels. The acquisition system is non-contacting and non-invasive with a pulsed laser source and a laser vibrometer detector. As the wave signatures of our targets are typically low in amplitude, we exploit multi-channel acquisition and processing techniques. These are commonly used in seismology to improve the signal-to-noise ratio of data. We identify vessel proxies with a diameter on the order of 1 mm, at a depth of 18 mm. Variations in scattered and photo-acoustic signatures are related to differences in vessel wall properties and content. The methods described have the potential to improve imaging and better inform interventions for atherosclerotic vessels, such as the carotid artery. Copyright © 2014 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  2. Fast Photo-detection in Phototransistors based on Group III-VI Layered Materials.

    NASA Astrophysics Data System (ADS)

    Patil, Prasanna; Ghosh, Sujoy; Wasala, Milinda; Lei, Sidong; Vajtai, Robert; Ajayan, Pulickel; Talapatra, Saikat

    Response time of a photo detector is one of the crucial aspect of photo-detection. Recently it has been shown that direct band gap of few layered group III-VI materials helps in increased absorption of light thereby enhancing the photo responsive properties of these materials. Ternary system of Copper Indium Selenide has been extensively used in optoelectronics industry and it is expected that 2D layered structure of Copper Indium Selenide will be a key component of future optoelectronics devices based on 2D materials. Here we report fast photo detection in few layers of Copper Indium Selenide (CuIn7Se11) phototransistor. Few-layers of CuIn7Se11 flakes were exfoliated from crystals grown using chemical vapor transport technique. Our photo response characterization indicates responsivity of 104 mA/W with external quantum efficiency exceeding 103. We have found response time of few μs which is one of the fastest response among photodetectors based on 2D materials. We also found specific detectivity of 1012 Jones which is an order higher than conventional photodetectors. A comparison between response times of various layered group III-VI materials will be presented and discussed. This work is supported by the U.S. Army Research Office through a MURI Grant # W911NF-11-1-0362.

  3. Controls on dissolved organic matter (DOM) degradation in a headwater stream: the influence of photochemical and hydrological conditions in determining light-limitation or substrate-limitation of photo-degradation

    NASA Astrophysics Data System (ADS)

    Cory, R. M.; Harrold, K. H.; Neilson, B. T.; Kling, G. W.

    2015-07-01

    We investigated how absorption of sunlight by chromophoric dissolved organic matter (CDOM) controls the degradation and export of DOM from Imnavait Creek, a beaded stream in the Alaskan Arctic. We measured concentrations of dissolved organic carbon (DOC), as well as concentrations and characteristics of CDOM and fluorescent dissolved organic matter (FDOM), during ice-free periods of 2011-2012 in the pools of Imnavait Creek and in soil waters draining to the creek. Spatial and temporal patterns in CDOM and FDOM in Imnavait Creek were analyzed in conjunction with measures of DOM degradation by sunlight and bacteria and assessments of hydrologic residence times and in situ UV exposure. CDOM was the dominant light attenuating constituent in the UV and visible portion of the solar spectrum, with high attenuation coefficients ranging from 86 ± 12 m-1 at 305 nm to 3 ± 1 m-1 in the photosynthetically active region (PAR). High rates of light absorption and thus light attenuation by CDOM contributed to thermal stratification in the majority of pools in Imnavait Creek under low-flow conditions. In turn, thermal stratification increased the residence time of water and DOM, and resulted in a separation of water masses distinguished by contrasting UV exposure (i.e., UV attenuation by CDOM with depth resulted in bottom waters receiving less UV than surface waters). When the pools in Imnavait Creek were stratified, DOM in the pool bottom water closely resembled soil water DOM in character, while the concentration and character of DOM in surface water was reproduced by experimental photo-degradation of bottom water. These results, in combination with water column rates of DOM degradation by sunlight and bacteria, suggest that photo-degradation is the dominant process controlling DOM fate and export in Imnavait Creek. A conceptual model is presented showing how CDOM amount and lability interact with incident UV light and water residence time to determine whether photo

  4. Performance analysis of single stage libr-water absorption machine operated by waste thermal energy of internal combustion engine: Case study

    NASA Astrophysics Data System (ADS)

    Sharif, Hafiz Zafar; Leman, A. M.; Muthuraman, S.; Salleh, Mohd Najib Mohd; Zakaria, Supaat

    2017-09-01

    Combined heating, cooling, and power is also known as Tri-generation. Tri-generation system can provide power, hot water, space heating and air -conditioning from single source of energy. The objective of this study is to propose a method to evaluate the characteristic and performance of a single stage lithium bromide-water (LiBr-H2O) absorption machine operated with waste thermal energy of internal combustion engine which is integral part of trigeneration system. Correlations for computer sensitivity analysis are developed in data fit software for (P-T-X), (H-T-X), saturated liquid (water), saturated vapor, saturation pressure and crystallization temperature curve of LiBr-H2O Solution. Number of equations were developed with data fit software and exported into excel work sheet for the evaluation of number of parameter concerned with the performance of vapor absorption machine such as co-efficient of performance, concentration of solution, mass flow rate, size of heat exchangers of the unit in relation to the generator, condenser, absorber and evaporator temperatures. Size of vapor absorption machine within its crystallization limits for cooling and heating by waste energy recovered from exhaust gas, and jacket water of internal combustion engine also presented in this study to save the time and cost for the facilities managers who are interested to utilize the waste thermal energy of their buildings or premises for heating and air conditioning applications.

  5. Photo-Curing: UV Radiation curing of polymers

    NASA Technical Reports Server (NTRS)

    Inman, Christina A.

    2004-01-01

    The Polymers Branch of the Materials Division is dedicated to the development of high-performance for a variety of applications. Areas of significant interest include high- temperature polymers, low density, and high strength insulating materials, conductive polymers, and high density polymer electrolytes. This summer our group is working diligently on a photo-curing project. There is interest in the medical community feel the need for a new and improved balloon that will be used for angioplasty (a form of heart surgery). This product should maintain flexibility but add many other properties. Like possibly further processability and resistance to infection. Our group intends on coming up with this product by using photo-enolization (or simply, photo-curing) by Diels-Alder trapping. The main objective was to synthesize a series of new polymers by Diels-Alder cycloaddition of photoenols with more elastomeric properties. Our group was responsible for performing the proper photo-curing techniques of the polymers with diacrylates and bismaleimides, synthesizing novel monomers, and evaluating experimental results. We attempted to use a diacrylate to synthesize the polymer because of previous research done within the Polymers Branch here at NASA. Most acrylates are commercially available, have more elastometric properties than a typical rigid aromatic structure has and they contain ethylene oxides in the middle of their structure that create extensive flexibility. The problem we encountered with the acrylates is that they photo chemically and thermally self polymerize and create diradicals at low temperatures; these constraints caused a lot of unnecessary side reactions. We want to promote solely, diketone polymerization because this type of polymerization has the ability to cause very elastic polymers. We chose to direct our attention towards the usage of maleimides because they are known for eliminating these unnecessary side reactions.

  6. Transient thermal effect, nonlinear refraction and nonlinear absorption properties of graphene oxide sheets in dispersion.

    PubMed

    Zhang, Xiao-Liang; Liu, Zhi-Bo; Li, Xiao-Chun; Ma, Qiang; Chen, Xu-Dong; Tian, Jian-Guo; Xu, Yan-Fei; Chen, Yong-Sheng

    2013-03-25

    The nonlinear refraction (NLR) properties of graphene oxide (GO) in N, N-Dimethylformamide (DMF) was studied in nanosecond, picosecond and femtosecond time regimes by Z-scan technique. Results show that the dispersion of GO in DMF exhibits negative NLR properties in nanosecond time regime, which is mainly attributed to transient thermal effect in the dispersion. The dispersion also exhibits negative NLR in picosecond and femtosecond time regimes, which are arising from sp(2)- hybridized carbon domains and sp(3)- hybridized matrix in GO sheets. To illustrate the relations between NLR and nonlinear absorption (NLA), NLA properties of the dispersion were also studied in nanosecond, picosecond and femtosecond time regimes.

  7. Ghost Spectroscopy with Classical Thermal Light Emitted by a Superluminescent Diode

    NASA Astrophysics Data System (ADS)

    Janassek, Patrick; Blumenstein, Sébastien; Elsäßer, Wolfgang

    2018-02-01

    We propose and realize the first classical ghost-imaging (GI) experiment in the frequency or wavelength domain, thus performing ghost spectroscopy using thermal light exhibiting photon bunching. The required wavelength correlations are provided by light emitted by spectrally broadband near-infrared amplified spontaneous emission of a semiconductor-based superluminescent diode. They are characterized by wavelength-resolved intensity cross-correlation measurements utilizing two-photon-absorption interferometry. Finally, a real-world spectroscopic application of this ghost spectroscopy with a classical light scheme is demonstrated in which an absorption band of trichloromethane (chloroform) at 1214 nm is reconstructed with a spectral resolution of 10 nm as a proof-of-principle experiment. This ghost-spectroscopy work fills the gap of a hitherto missing analogy between the spatial and the spectral domain in classical GI modalities, with the expectation of contributing towards a broader dissemination of correlated photon ghost modalities, hence paving the way towards more applications which exploit the favorable advantages.

  8. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  9. Photo-oxidative degradation of TiO{sub 2}/polypropylene films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    García-Montelongo, X.L.; Martínez-de la Cruz, A., E-mail: azael70@yahoo.com.mx; Vázquez-Rodríguez, S.

    Graphical abstract: - Highlights: • Photo-oxidative degradation of polypropylene is accelerated by TiO{sub 2} incorporation. • Weight loss, FTIR, SEM and GPC shown high degree of degradation of polypropylene. • A mechanism of the photo-degradation of polypropylene by TiO{sub 2} is proposed. - Abstract: Photo-oxidative degradation of polypropylene films with TiO{sub 2} nanoparticles incorporated was studied in a chamber of weathering with Xenon lamps as irradiation source. TiO{sub 2} powder with crystalline structure of anatase was synthesized by thermal treatments at 400 and 500 °C starting from a precursor material obtained by sol–gel method. Composites of TiO{sub 2}/polypropylene were preparedmore » with 0.1, 0.5 and 1.0 wt% of TiO{sub 2}. The mixture of components was performed using a twin screw extruder, the resulting material was pelletized by mechanical fragmenting and then hot-pressed in order to form polypropylene films with TiO{sub 2} dispersed homogeneously. Photo-oxidative degradation process was followed by visual inspection, weight loss of films, scanning electron microscopy (SEM), infrared spectroscopy with Fourier transformed (FTIR), and gel permeation chromatography (GPC)« less

  10. Gate Tuning of Förster Resonance Energy Transfer in a Graphene - Quantum Dot FET Photo-Detector.

    PubMed

    Li, Ruifeng; Schneider, Lorenz Maximilian; Heimbrodt, Wolfram; Wu, Huizhen; Koch, Martin; Rahimi-Iman, Arash

    2016-06-20

    Graphene photo-detectors functionalized by colloidal quantum dots (cQDs) have been demonstrated to show effective photo-detection. Although the transfer of charge carriers or energy from the cQDs to graphene is not sufficiently understood, it is clear that the mechanism and efficiency of the transfer depends on the morphology of the interface between cQDs and graphene, which is determined by the shell of the cQDs in combination with its ligands. Here, we present a study of a graphene field-effect transistor (FET), which is functionalized by long-ligand CdSe/ZnS core/shell cQDs. Time-resolved photo-luminescence from the cQDs as a function of the applied gate voltage has been investigated in order to probe transfer dynamics in this system. Thereby, a clear modification of the photo-luminescence lifetime has been observed, indicating a change of the decay channels. Furthermore, we provide responsivities under a Förster-like energy transfer model as a function of the gate voltage in support of our findings. The model shows that by applying a back-gate voltage to the photo-detector, the absorption can be tuned with respect to the photo-luminescence of the cQDs. This leads to a tunable energy transfer rate across the interface of the photo-detector, which offers an opportunity to optimize the photo-detection.

  11. NGEE Arctic TIR and Digital Photos, Drained Thaw Lake Basin, Barrow, Alaska, July 2015

    DOE Data Explorer

    Shawn Serbin; Wil Lieberman-Cribbin; Kim Ely; Alistair Rogers

    2016-11-01

    FLIR thermal infrared (TIR), digital camera photos, and plot notes across the Barrow, Alaska DTLB site. Data were collected together with measurements of canopy spectral reflectance (see associated metadata record (NGEE Arctic HR1024i Canopy Spectral Reflectance, Drained Thaw Lake Basin, Barrow, Alaska, July 2015 ). Data contained within this archive include exported FLIR images (analyzed with FLIR-Tools), digital photos, TIR report, and sample notes. Further TIR image analysis can be conducted in FLIR-Tools.

  12. Vehicle Thermal Management Facilities | Transportation Research | NREL

    Science.gov Websites

    Management Facilities Vehicle Thermal Management Facilities Image of a building with two semi truck evaluation facilities to develop advanced thermal management technologies for vehicles. Vehicle Testing and apparatus. Combined fluid loops bench research apparatus in the Vehicle Thermal Management Laboratory. Photo

  13. Electric-Drive Vehicle Thermal Performance Benchmarking | Transportation

    Science.gov Websites

    studies are as follows: Characterize the thermal resistance and conductivity of various layers in the Research | NREL Electric-Drive Vehicle Thermal Performance Benchmarking Electric-Drive Vehicle Thermal Performance Benchmarking A photo of the internal components of an automotive inverter. NREL

  14. Heat dissipation by blood circulation and airway tissue heat absorption in a canine model of inhalational thermal injury.

    PubMed

    Wan, Jiangbo; Zhang, Guoan; Qiu, Yuxuan; Wen, Chunquan; Fu, Tairan

    2016-05-01

    This study aimed to further explore heat dissipation by blood circulation and airway tissue heat absorption in an inhalational thermal injury model. Twelve adult male Beagle dogs were divided into four groups to inhale heated air for 10min: the control group, group I (100.5°C), group II (161.5°C), and group III (218°C). The relative humidity and temperature of the inhaled heated air were measured in the heating tube and trachea, as were blood temperatures and flow velocities in both common jugular veins. Formulas were used to calculate the total heat quantity reduction of the heated air, heat dissipation by the blood, and airway tissue heat absorption. The blood temperatures of both the common jugular veins increased by 0.29°C±0.07°C to 2.96°C±0.24°C and the mean blood flow volume after injury induction was about 1.30-1.74 times greater than before injury induction. The proportions of heat dissipated by the blood and airway tissue heat absorption were 68.92%±14.88% and 31.13%±14.87%, respectively. The heat dissipating ability of the blood circulation was demonstrated and improved upon along with tissue heat absorption owing to increased regional blood flow. Copyright © 2015 Elsevier Ltd and ISBI. All rights reserved.

  15. Combined chemo- and photo-thermal therapy delivered by multifunctional theranostic gold nanorod-loaded microcapsules

    NASA Astrophysics Data System (ADS)

    Chen, Haiyan; di, Yingfeng; Chen, Dan; Madrid, Kyle; Zhang, Min; Tian, Caiping; Tang, Liping; Gu, Yueqing

    2015-05-01

    A polyelectrolyte microcapsule-based, cancer-targeting, and controlled drug delivery system has been developed as a multifunctional theranostic agent for synergistic cancer treatment. This new system, called FA-MC@GNR, is composed of folic acid (FA)-modified, multi-layered, hollow microcapsules loaded with gold nanorods (GNRs), and undergoes thermal degradation under near infrared (NIR) light. Either an NIR dye (MPA) or anti-cancer drug (doxorubicin, DOX) was loaded into the microcapsules via physical adsorption, yielding FA-MC@GNRs/MPA or FA-MC@GNRs/DOX, both of which exhibit no obvious toxicity, high stability, and remarkably improved tumor-targeting capabilities in vivo. Utilizing the strong NIR absorption of FA-MC@GNRs/DOX, we demonstrate the system's ability to simultaneously elicit photothermal therapy and controlled chemotherapy, achieving synergistic cancer treatment both in vitro cellular and in vivo animal experiments. Our study presents a new type of multifunctional micro-carrier for the delivery of chemotherapeutic drugs and photothermal agents, which has been shown to be an effective therapeutic approach for combined cancer treatment.

  16. Citric-Acid-Derived Photo-cross-Linked Biodegradable Elastomers

    PubMed Central

    Gyawali, Dipendra; Tran, Richard T.; Guleserian, Kristine J.; Tang, Liping; Yang, Jian

    2010-01-01

    Citric-acid-derived thermally cross-linked biodegradable elastomers (CABEs) have recently received significant attention in various biomedical applications, including tissue-engineering orthopedic devices, bioimaging and implant coatings. However, citric-acid-derived photo-cross-linked biodegradable elastomers are rarely reported. Herein, we report a novel photo-cross-linked biodegradable elastomer, referred to as poly(octamethylene maleate citrate) (POMC), which preserves pendant hydroxyl and carboxylic functionalities after cross-linking for the potential conjugation of biologically active molecules. POMC is a low-molecular-mass pre-polymer with a molecular mass average between 701 and 1291 Da. POMC networks are soft and elastic with an initial modulus of 0.07 to 1.3 MPa and an elongation at break between 38 and 382%. FT-IR–ATR results confirmed the successful surface immobilization of type-I collagen onto POMC films, which enhanced in vitro cellular attachment and proliferation. Photo-polymerized POMC films implanted subcutaneously into Sprague–Dawley rats demonstrated minimal in vivo inflammatory responses. The development of POMC enriches the family of citric-acid-derived biodegradable elastomers and expands the available biodegradable polymers for versatile needs in biomedical applications. PMID:20557687

  17. Photo-oxidation catalysts

    DOEpatents

    Pitts, J Roland [Lakewood, CO; Liu, Ping [Irvine, CA; Smith, R Davis [Golden, CO

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  18. Thermal annihilation of photo-induced radicals following dynamic nuclear polarization to produce transportable frozen hyperpolarized 13C-substrates

    PubMed Central

    Capozzi, Andrea; Cheng, Tian; Boero, Giovanni; Roussel, Christophe; Comment, Arnaud

    2017-01-01

    Hyperpolarization via dynamic nuclear polarization (DNP) is pivotal for boosting magnetic resonance imaging (MRI) sensitivity and dissolution DNP can be used to perform in vivo real-time 13C MRI. The type of applications is however limited by the relatively fast decay time of the hyperpolarized spin state together with the constraint of having to polarize the 13C spins in a dedicated apparatus nearby but separated from the MRI magnet. We herein demonstrate that by polarizing 13C with photo-induced radicals, which can be subsequently annihilated using a thermalization process that maintains the sample temperature below its melting point, hyperpolarized 13C-substrates can be extracted from the DNP apparatus in the solid form, while maintaining the enhanced 13C polarization. The melting procedure necessary to transform the frozen solid into an injectable solution containing the hyperpolarized 13C-substrates can therefore be performed ex situ, up to several hours after extraction and storage of the polarized solid. PMID:28569840

  19. Photochemical primary process of photo-Fries rearrangement reaction of 1-naphthyl acetate as studied by MFE probe.

    PubMed

    Gohdo, Masao; Takamasu, Tadashi; Wakasa, Masanobu

    2011-01-14

    Photo-Fries rearrangement reactions of 1-naphthyl acetate (NA) in n-hexane and in cyclohexane were studied by the magnetic field effect probe (MFE probe) under magnetic fields (B) of 0 to 7 T. Transient absorptions of the 1-naphthoxyl radical, T-T absorption of NA, and a short-lifetime intermediate (τ = 24 ns) were observed by a nanosecond laser flash photolysis technique. In n-hexane, the yield of escaped 1-naphthoxyl radicals dropped dramatically upon application of a 3 mT field, but then the yield increased with increasing B for 3 mT < B≤ 7 T. These observed MFEs can be explained by the hyperfine coupling and the Δg mechanisms through the singlet radical pair. The fact that MFEs were observed for the present photo-Fries rearrangement reaction indicates the presence of a singlet radical pair intermediate with a lifetime as long as several tens of nanoseconds.

  20. Nanostructures Exploit Hybrid-Polariton Resonances

    NASA Technical Reports Server (NTRS)

    Anderson, Mark

    2008-01-01

    Nanostructured devices that exploit the hybrid-polariton resonances arising from coupling among photons, phonons, and plasmons are subjects of research directed toward the development of infrared-spectroscopic sensors for measuring extremely small quantities of molecules of interest. The spectroscopic techniques in question are surface enhanced Raman scattering (SERS) and surface enhanced infrared absorption (SEIRA). An important intermediate goal of this research is to increase the sensitivity achievable by these techniques. The basic idea of the approach being followed in this research is to engineer nanostructured devices and thereby engineer their hybrid-polariton resonances to concentrate infrared radiation incident upon their surfaces in such a manner as to increase the absorption of the radiation for SEIRA and measure the frequency shifts of surface vibrational modes. The underlying hybrid-polariton-resonance concept is best described by reference to experimental devices that have been built and tested to demonstrate the concept. The nanostructure of each such device includes a matrix of silicon carbide particles of approximately 1 micron in diameter that are supported on a potassium bromide (KBr) or poly(tetrafluoroethylene) [PTFE] window. These grains are sputter-coated with gold grains of 40-nm size (see figure). From the perspective of classical electrodynamics, in this nanostructure, that includes a particulate or otherwise rough surface, the electric-field portion of an incident electromagnetic field becomes concentrated on the particles when optical resonance conditions are met. Going beyond the perspective of classical electrodynamics, it can be seen that when the resonance frequencies of surface phonons and surface plasmons overlap, the coupling of the resonances gives rise to an enhanced radiation-absorption or -scattering mechanism. The sizes, shapes, and aggregation of the particles determine the frequencies of the resonances. Hence, the task of

  1. Ex vivo validation of photo-magnetic imaging.

    PubMed

    Luk, Alex; Nouizi, Farouk; Erkol, Hakan; Unlu, Mehmet B; Gulsen, Gultekin

    2017-10-15

    We recently introduced a new high-resolution diffuse optical imaging technique termed photo-magnetic imaging (PMI), which utilizes magnetic resonance thermometry (MRT) to monitor the 3D temperature distribution induced in a medium illuminated with a near-infrared light. The spatiotemporal temperature distribution due to light absorption can be accurately estimated using a combined photon propagation and heat diffusion model. High-resolution optical absorption images are then obtained by iteratively minimizing the error between the measured and modeled temperature distributions. We have previously demonstrated the feasibility of PMI with experimental studies using tissue simulating agarose phantoms. In this Letter, we present the preliminary ex vivo PMI results obtained with a chicken breast sample. Similarly to the results obtained on phantoms, the reconstructed images reveal that PMI can quantitatively resolve an inclusion with a 3 mm diameter embedded deep in a biological tissue sample with only 10% error. These encouraging results demonstrate the high performance of PMI in ex vivo biological tissue and its potential for in vivo imaging.

  2. Evidence of photo- and thermal-induced reversible intermolecular hydrogen-atom transfer in. gamma. -irradiated thiourea clathrates as studied by electron spin resonance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ichikawa, T.

    1979-05-17

    There has been a report (M. Iwasaki and Toriyama) on an electron spin resonance study of reversible intramolecular radical conversion due to photo- and thermal-induced H-atom transfer. Schlenk, Brown, White, Chatini, and Nakatani reported H-atom abstraction of a photostimulated allylic radical from its neighbor molecules and thermal recovery of the allylic radical from photoirradiation in a thiourea clathrate. Radiolysis of a thiourea clathrate containing a mixture of 10 mol% 2,3-dimethylbutadiene and 90 mol% 2,3-dimethylbutane gave a resolved room-temperature spectrum. The result seemed to suggest that the monomer radical was stabilized in the canal even at room temperature in the presencemore » of the inert DBA molecules which might block chain propagation. Results suggested that the photostimulated R/sub 1/, radicals abstract H atoms from DBA molecules to form tetramethylethylene molecules and R/sub 2/ radicals and that the R/sub 2/ radicals produced by photoirradiation abstract H atoms from TME molecules to regenerate R/sub 1/ radicals and DBA molecules. 2 figures. (DP)« less

  3. Influence of surface states of CuInS2 quantum dots in quantum dots sensitized photo-electrodes

    NASA Astrophysics Data System (ADS)

    Peng, Zhuoyin; Liu, Yueli; Wu, Lei; Zhao, Yinghan; Chen, Keqiang; Chen, Wen

    2016-12-01

    Surface states are significant factor for the enhancement of electrochemical performance in CuInS2 quantum dot sensitized photo-electrodes. DDT, OLA, MPA, and S2- ligand capped CuInS2 quantum dot sensitized photo-electrodes are prepared by thermolysis, solvethermal and ligand-exchange processes, respectively, and their optical properties and photoelectrochemical properties are investigated. The S2- ligand enhances the UV-vis absorption and electron-hole separation property as well as the excellent charge transfer performance of the photo-electrodes, which is attributed to the fact that the atomic S2- ligand for the interfacial region of quantum dots may improve the electron transfer rate. These S2--capped CuInS2 quantum dot sensitized photo-electrodes exhibit the excellent photoelectrochemical efficiency and IPCE peak value, which is higher than that of the samples with DDT, OLA and MPA ligands.

  4. Polar Lunar Regions: Exploiting Natural and Augmented Thermal Environments

    NASA Technical Reports Server (NTRS)

    Ryan, Robert E.; McKellip, Rodney; Brannon, David P.; Underwood, Lauren; Russell, Kristen J.

    2007-01-01

    In polar regions of the Moon, some areas within craters are permanently shadowed from solar illumination and can reach temperatures of 100 K or less. These regions could serve as cold traps, capturing ice and other volatile compounds. These potential ice stores have many applications for lunar exploration. Within double-shaded craters, even colder regions exist, with temperatures never exceeding 50 K in many cases. Observed temperatures suggest that these regions could enable equivalent liquid nitrogen cryogenic functions. These permanently shaded polar craters also offer unprecedented high-vacuum cryogenic environments, which in their current state could support cryogenic applications. Besides ice stores, the unique conditions at the lunar poles harbor an environment that provides an opportunity to reduce the power, weight, and total mass that needs to be carried from the Earth to the Moon for lunar exploration and research. Reducing the heat flux of geothermal, black body radiation can have significant impacts on the achievable temperature. With a few manmade augmentations, permanently shaded craters located near the lunar poles achieve temperatures even lower than those that naturally exist. Our analysis reveals that lightweight thermal shielding within shaded craters could create an environment several Kelvin above absolute zero. The temperature ranges of both naturally shaded and thermally augmented craters could enable the long-term storage of most gases, low-temperature superconductors for large magnetic fields, devices and advanced high-speed computing instruments. Augmenting thermal conditions in these craters could then be used as a basis for the development of an advanced thermal management architecture that would support a wide variety of cryogenically based applications. Lunar exploration and habitation capabilities would significantly benefit if permanently shaded craters, augmented with thermal shielding, were used to facilitate the operation of near

  5. Polar Lunar Regions: Exploiting Natural and Augmented Thermal Environments

    NASA Astrophysics Data System (ADS)

    Ryan, R. E.; McKellip, R. C.; Brannon, D. P.; Underwood, L. W.; Russell, K. J.

    2007-12-01

    In polar regions of the Moon, there are areas within craters that are permanently shadowed from solar illumination, which can reach temperatures of 100K or less. These regions could serve as cold traps, capturing ice and other volatile compounds. These potential ice stores have many applications for lunar exploration. Within double-shaded craters, even colder regions exist, with temperatures never exceeding 50K in many cases. Temperatures observed in theses regions suggest that they could enable equivalent liquid nitrogen cryogenic functions. These permanently shaded polar craters also offer unprecedented high vacuum cryogenic environments, which in their current state could support cryogenic applications. The unique conditions at the lunar poles, besides ice stores, harbor an environment that provides an opportunity to reduce the power, weight and total mass that needs to be carried from the Earth to the moon for lunar exploration and research. Reducing the heat flux of geothermal, black body radiation can have significant impacts on the achievable temperature. With a few man-made augmentations, permanently shaded craters located near the lunar poles achieve temperatures even lower than those that naturally exist there. Our analysis reveals that lightweight thermal shielding, within shaded craters, could create an environment several Kelvin above absolute zero. The temperature ranges of naturally shaded craters and thermally augmented ones could enable the long-term storage of most gases, low temperature superconductors for large magnetic fields, devices and advanced high speed computing instruments. Augmenting thermal conditions in these craters could then be used as a basis for the development of an advanced thermal management architecture that would support a wide variety of cryogenically based applications. Lunar exploration and habitation capabilities would significantly benefit if permanently shaded craters, augmented with thermal shielding, were to be used

  6. Thermal energy transformer

    NASA Technical Reports Server (NTRS)

    Berdahl, C. M.; Thiele, C. L. (Inventor)

    1979-01-01

    For use in combination with a heat engine, a thermal energy transformer is presented. It is comprised of a flux receiver having a first wall defining therein a radiation absorption cavity for converting solar flux to thermal energy, and a second wall defining an energy transfer wall for the heat engine. There is a heat pipe chamber interposed between the first and second walls having a working fluid disposed within the chamber and a wick lining the chamber for conducting the working fluid from the second wall to the first wall. Thermal energy is transferred from the radiation absorption cavity to the heat engine.

  7. Hib Photos

    MedlinePlus

    ... fluid culture positive for Haemophilus influenzae , type b (Gram stain) www.vaccineinformation.org/photos/hib_aap001.jpg Copyright American Academy of Pediatrics Haemophilus influenzae type b. ... gram-negative Haemophilus influenzae bacteria www.vaccineinformation.org/photos/ ...

  8. Aerial photo SBVC1962". Photo no. 360. Low oblique aerial view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Aerial photo -SBVC-1962". Photo no. 360. Low oblique aerial view of the campus, looking southeast. Stamped on the rear: "Ron Wilhite, Sun-Telegram photo, file, 10/22/62/ - San Bernardino Valley College, 701 South Mount Vernon Avenue, San Bernardino, San Bernardino County, CA

  9. Active correction of thermal lensing through external radiative thermal actuation.

    PubMed

    Lawrence, Ryan; Ottaway, David; Zucker, Michael; Fritschel, Peter

    2004-11-15

    Absorption of laser beam power in optical elements induces thermal gradients that may cause unwanted phase aberrations. In precision measurement applications, such as laser interferometric gravitational-wave detection, corrective measures that require mechanical contact with or attachments to the optics are precluded by noise considerations. We describe a radiative thermal corrector that can counteract thermal lensing and (or) thermoelastic deformation induced by coating and substrate absorption of collimated Gaussian beams. This radiative system can correct anticipated distortions to a high accuracy, at the cost of an increase in the average temperature of the optic. A quantitative analysis and parameter optimization is supported by results from a simplified proof-of-principle experiment, demonstrating the method's feasibility for our intended application.

  10. Influence of thermal light correlations on photosynthetic structures

    NASA Astrophysics Data System (ADS)

    de Mendoza, Adriana; Manrique, Pedro; Caycedo-Soler, Felipe; Johnson, Neil F.; Rodríguez, Ferney J.; Quiroga, Luis

    2014-03-01

    The thermal light from the sun is characterized by both classical and quantum mechanical correlations. These correlations have left a fingerprint on the natural harvesting structures developed through five billion years of evolutionary pressure, specially in photosynthetic organisms. In this work, based upon previous extensive studies of spatio-temporal correlations of light fields, we hypothesize that structures involving photosensitive pigments like those present in purple bacteria vesicles emerge as an evolutionary response to the different properties of incident light. By using burstiness and memory as measures that quantify higher moments of the photon arrival statistics, we generate photon-time traces. They are used to simulate absorption on detectors spatially extended over regions comparable to these light fields coherence length. Finally, we provide some insights into the connection between these photo-statistical features with the photosynthetic membrane architecture and the lights' spatial correlation. Facultad de Ciencias Uniandes.

  11. Mass-dependent and Mass-independent Sulphur Isotope Fractionation Accompanying Thermal- and Photo-chemical Decomposition of Sulphur Bearing Organic Compounds

    NASA Astrophysics Data System (ADS)

    Oduro, Harry; Izon, Gareth; Ono, Shuhei

    2014-05-01

    The bimodal S-isotope record, specifically the transition from mass independent (MIF) to mass dependent fractionation (MDF), is perhaps the most widely cited line of evidence for an irreversible rise in atmospheric oxygen at ca. 2.4Ga. The production and preservation of S-MIF, manifested in both Δ33S and Δ36S, within the geological record are linked to atmospheric O2 via a number of arguments. However, to date, the only mechanism capable of generating S-MIF consistent with the Archaean sedimentary records involves gas-phase ultraviolet irradiation of SO21 photolysis. More recently, Δ33S S-MIF trends have been reported from en vitro thermochemical sulphate reduction (TSR) experiments, prompting authors to question the importance of S-MIF as a proxy for Earth oxidation2. Importantly, whilst emerging TSR experiments3,4 affirm the reported Δ33S trends2, these experiments fail to identify correlated S-MIF between Δ33S and Δ36S values3,4. Realization that S-MIF is confined to Δ33S during TSR, precludes TSR as a mechanism responsible for the origin of the Archaean S-MIF record but strongly suggests the effect originating from a magnetic isotope effect (MIE) associated with 33S nucleus3,4. Clearly, photochemical and thermochemical processes impart different Δ36S/Δ33S trends with significant variation in δ34S; however, a complete experimental elucidation of mechanisms responsible for the S-MIF and S-MIE signatures is lacking. Interestingly, a complete understanding of the S-isotope chemistry during thermal- and photo-chemical decomposition may reveal wavelength and thermal dependence archived in the sedimentary record. Here we extend the experimental database to explore the magnitude and sign of Δ36S/Δ33S and δ34S produced during both photo- and thermochemical processes. Here the organic sulphur compounds (OSC) utilized in these experiments carries diagnostic Δ36S/Δ33S patterns that differ from those reported from photolysis experiment SO2 and from the

  12. Bulk damage and absorption in fused silica due to high-power laser applications

    NASA Astrophysics Data System (ADS)

    Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

    2015-11-01

    Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

  13. Coupled dual loop absorption heat pump

    DOEpatents

    Sarkisian, Paul H.; Reimann, Robert C.; Biermann, Wendell J.

    1985-01-01

    A coupled dual loop absorption system which utilizes two separate complete loops. Each individual loop operates at three temperatures and two pressures. This low temperature loop absorber and condenser are thermally coupled to the high temperature loop evaporator, and the high temperature loop condenser and absorber are thermally coupled to the low temperature generator.

  14. The Lattice and Thermal Radiation Conductivity of Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Spuckler, Charles M.

    2008-01-01

    The lattice and radiation conductivity of thermal barrier coatings was evaluated using a laser heat flux approach. A diffusion model has been established to correlate the apparent thermal conductivity of the coating to the lattice and radiation conductivity. The radiation conductivity component can be expressed as a function of temperature and the scattering and absorption properties of the coating material. High temperature scattering and absorption of the coating systems can also be derived based on the testing results using the modeling approach. The model prediction is found to have good agreement with experimental observations.

  15. Optical absorption of carbon-gold core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Zhaolong; Quan, Xiaojun; Zhang, Zhuomin; Cheng, Ping

    2018-01-01

    In order to enhance the solar thermal energy conversion efficiency, we propose to use carbon-gold core-shell nanoparticles dispersed in liquid water. This work demonstrates theoretically that an absorbing carbon (C) core enclosed in a plasmonic gold (Au) nanoshell can enhance the absorption peak while broadening the absorption band; giving rise to a much higher solar absorption than most previously studied core-shell combinations. The exact Mie solution is used to evaluate the absorption efficiency factor of spherical nanoparticles in the wavelength region from 300 nm to 1100 nm as well as the electric field and power dissipation profiles inside the nanoparticles at specified wavelengths (mostly at the localized surface plasmon resonance wavelength). The field enhancement by the localized plasmons at the gold surfaces boosts the absorption of the carbon particle, resulting in a redshift of the absorption peak with increased peak height and bandwidth. In addition to spherical nanoparticles, we use the finite-difference time-domain method to calculate the absorption of cubic core-shell nanoparticles. Even stronger enhancement can be achieved with cubic C-Au core-shell structures due to the localized plasmonic resonances at the sharp edges of the Au shell. The solar absorption efficiency factor can exceed 1.5 in the spherical case and reach 2.3 in the cubic case with a shell thickness of 10 nm. Such broadband absorption enhancement is in great demand for solar thermal applications including steam generation.

  16. Skin autofluorescence photo-bleaching and photo-memory

    NASA Astrophysics Data System (ADS)

    Lesins, Janis; Lihachev, Alexey; Rudys, Romualdas; Bagdonas, Saulius; Spigulis, Janis

    2011-07-01

    Photo-bleaching of in-vivo skin autofluorescence intensity under continuous low power laser irradiation has been studied. Temporal behavior of single-spot fluorescence and spectral fluorescent images have been studied at continuous 405 nm, 473 nm and 532 nm laser excitation and/or pre-irradiation, with power densities well below the laser-skin safety limits. Skin autofluorescence photo-memory effects (laser signatures) have been observed and analyzed, as well.

  17. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Storms Laboratory (NSSL) Collection Credit: NOAA Photo Library, NOAA Central Library; OAR/ERL/National

  18. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL) Category

  19. Monte Carlo simulations of the detailed iron absorption line profiles from thermal winds in X-ray binaries

    NASA Astrophysics Data System (ADS)

    Tomaru, Ryota; Done, Chris; Odaka, Hirokazu; Watanabe, Shin; Takahashi, Tadayuki

    2018-05-01

    Blueshifted absorption lines from highly ionized iron are seen in some high inclination X-ray binary systems, indicating the presence of an equatorial disc wind. This launch mechanism is under debate, but thermal driving should be ubiquitous. X-ray irradiation from the central source heats disc surface, forming a wind from the outer disc where the local escape velocity is lower than the sound speed. The mass-loss rate from each part of the disc is determined by the luminosity and spectral shape of the central source. We use these together with an assumed density and velocity structure of the wind to predict the column density and ionization state, then combine this with a Monte Carlo radiation transfer to predict the detailed shape of the absorption (and emission) line profiles. We test this on the persistent wind seen in the bright neutron star binary GX 13+1, with luminosity L/LEdd ˜ 0.5. We approximately include the effect of radiation pressure because of high luminosity, and compute line features. We compare these to the highest resolution data, the Chandra third-order grating spectra, which we show here for the first time. This is the first physical model for the wind in this system, and it succeeds in reproducing many of the features seen in the data, showing that the wind in GX13+1 is most likely a thermal-radiation driven wind. This approach, combined with better streamline structures derived from full radiation hydrodynamic simulations, will allow future calorimeter data to explore the detail wind structure.

  20. Heat transfer in fish: are short excursions between habitats a thermoregulatory behaviour to exploit resources in an unfavourable thermal environment?

    PubMed

    Pépino, Marc; Goyer, Katerine; Magnan, Pierre

    2015-11-01

    Temperature is the primary environmental factor affecting physiological processes in ectotherms. Heat-transfer models describe how the fish's internal temperature responds to a fluctuating thermal environment. Specifically, the rate coefficient (k), defined as the instantaneous rate of change in body temperature in relation to the difference between ambient and body temperature, summarizes the combined effects of direct thermal conduction through body mass, passive convection (intracellular and intercellular fluids) and forced convective heat transfer (cardiovascular system). The k-coefficient is widely used in fish ecology to understand how body temperature responds to changes in water temperature. The main objective of this study was to estimate the k-coefficient of brook charr equipped with internal temperature-sensitive transmitters in controlled laboratory experiments. Fish were first transferred from acclimation tanks (10°C) to tanks at 14, 19 or 23°C (warming experiments) and were then returned to the acclimation tanks (10°C; cooling experiments), thus producing six step changes in ambient temperature. We used non-linear mixed models to estimate the k-coefficient. Model comparisons indicated that the model incorporating the k-coefficient as a function of absolute temperature difference (dT: 4, 9 and 13°C) best described body temperature change. By simulating body temperature in a heterogeneous thermal environment, we provide theoretical predictions of maximum excursion duration between feeding and resting areas. Our simulations suggest that short (i.e. <60 min) excursions could be a common thermoregulatory behaviour adopted by cold freshwater fish species to sustain body temperature below a critical temperature threshold, enabling them to exploit resources in an unfavourable thermal environment. © 2015. Published by The Company of Biologists Ltd.

  1. Graphene-based absorber exploiting guided mode resonances in one-dimensional gratings.

    PubMed

    Grande, M; Vincenti, M A; Stomeo, T; Bianco, G V; de Ceglia, D; Aközbek, N; Petruzzelli, V; Bruno, G; De Vittorio, M; Scalora, M; D'Orazio, A

    2014-12-15

    A one-dimensional dielectric grating, based on a simple geometry, is proposed and investigated to enhance light absorption in a monolayer graphene exploiting guided mode resonances. Numerical findings reveal that the optimized configuration is able to absorb up to 60% of the impinging light at normal incidence for both TE and TM polarizations resulting in a theoretical enhancement factor of about 26 with respect to the monolayer graphene absorption (≈2.3%). Experimental results confirm this behavior showing CVD graphene absorbance peaks up to about 40% over narrow bands of a few nanometers. The simple and flexible design points to a way to realize innovative, scalable and easy-to-fabricate graphene-based optical absorbers.

  2. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Photographer: Jim Leonard Credit: NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms

  3. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Ainsworth Credit: NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL

  4. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image - nssl0059 Tornado in mature stage of development. Photo #3 of a series of classic photographs of this

  5. Battery and Thermal Energy Storage | Energy Systems Integration Facility |

    Science.gov Websites

    NREL Battery and Thermal Energy Storage Battery and Thermal Energy Storage Not long ago, the performance of grid-integrated battery and thermal energy storage technologies. Photo of a battery energy . NREL is also creating better materials for batteries and thermal storage devices to improve their

  6. 53. Historic American Buildings Survey Photo by Slevin Photo Taken: ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    53. Historic American Buildings Survey Photo by Slevin Photo Taken: April 1908 RUINS OF MISSION QUANDRANGLE - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

  7. Radiative bistability and thermal memory.

    PubMed

    Kubytskyi, Viacheslav; Biehs, Svend-Age; Ben-Abdallah, Philippe

    2014-08-15

    We predict the existence of a thermal bistability in many-body systems out of thermal equilibrium which exchange heat by thermal radiation using insulator-metal transition materials. We propose a writing-reading procedure and demonstrate the possibility to exploit the thermal bistability to make a volatile thermal memory. We show that this thermal memory can be used to store heat and thermal information (via an encoding temperature) for arbitrary long times. The radiative thermal bistability could find broad applications in the domains of thermal management, information processing, and energy storage.

  8. Photo- and electroproduction of K+Λ with a unitarity-restored isobar model

    NASA Astrophysics Data System (ADS)

    Skoupil, D.; Bydžovský, P.

    2018-02-01

    Exploiting the isobar model, kaon photo- and electroproduction on the proton in the resonance region comes under scrutiny. An upgrade of our previous model, comprising higher-spin nucleon and hyperon exchanges in the consistent formalism, was accomplished by implementing energy-dependent widths of nucleon resonances, which leads to a different choice of hadron form factor with much softer values of cutoff parameter for the resonant part. For a reliable description of electroproduction, the necessity of including longitudinal couplings of nucleon resonances to virtual photons was revealed. We present a new model whose free parameters were adjusted to photo- and electroproduction data and which provides a reliable overall description of experimental data in all kinematic regions. The majority of nucleon resonances chosen in this analysis coincide with those selected in our previous analysis and also in the Bayesian analysis with the Regge-plus-resonance model as the states contributing to this process with the highest probability.

  9. Method for measuring thermal properties using a long-wavelength infrared thermal image

    DOEpatents

    Walker, Charles L [Albuquerque, NM; Costin, Laurence S [Albuquerque, NM; Smith, Jody L [Albuquerque, NM; Moya, Mary M [Albuquerque, NM; Mercier, Jeffrey A [Albuquerque, NM

    2007-01-30

    A method for estimating the thermal properties of surface materials using long-wavelength thermal imagery by exploiting the differential heating histories of ground points in the vicinity of shadows. The use of differential heating histories of different ground points of the same surface material allows the use of a single image acquisition step to provide the necessary variation in measured parameters for calculation of the thermal properties of surface materials.

  10. Dinuclear PhotoCORMs: Dioxygen-Assisted Carbon Monoxide Uncaging from Long-Wavelength-Absorbing Metal-Metal-Bonded Carbonyl Complexes.

    PubMed

    Li, Zhi; Pierri, Agustin E; Huang, Po-Ju; Wu, Guang; Iretskii, Alexei V; Ford, Peter C

    2017-06-05

    We describe a new strategy for triggering the photochemical release of caged carbon monoxide (CO) in aerobic media using long-wavelength visible and near-infrared (NIR) light. The dinuclear rhenium-manganese carbonyl complexes (CO) 5 ReMn(CO) 3 (L), where L = phenanthroline (1), bipyridine (2), biquinoline (3), or phenanthrolinecarboxaldehyde (4), each show a strong metal-metal-bond-to-ligand (σ MM → π L *) charge-transfer absorption band at longer wavelengths. Photolysis with deep-red (1 and 2) or NIR (3 and 4) light leads to homolytic cleavage of the Re-Mn bonds to give mononuclear metal radicals. In the absence of trapping agents, these radicals primarily recombine to reform dinuclear complexes. In oxygenated media, however, the radicals react with dioxygen to form species much more labile toward CO release via secondary thermal and/or photochemical reactions. Conjugation of 4, with an amine-terminated poly(ethylene glycol) oligomer, gives a water-soluble derivative with similar photochemistry. In this context, we discuss the potential applications of these dinuclear complexes as visible/NIR-light-photoactivated CO-releasing moieties (photoCORMs).

  11. Separating higher-order nonlinearities in transient absorption microscopy

    NASA Astrophysics Data System (ADS)

    Wilson, Jesse W.; Anderson, Miguel; Park, Jong Kang; Fischer, Martin C.; Warren, Warren S.

    2015-08-01

    The transient absorption response of melanin is a promising optically-accessible biomarker for distinguishing malignant melanoma from benign pigmented lesions, as demonstrated by earlier experiments on thin sections from biopsied tissue. The technique has also been demonstrated in vivo, but the higher optical intensity required for detecting these signals from backscattered light introduces higher-order nonlinearities in the transient response of melanin. These components that are higher than linear with respect to the pump or the probe introduce intensity-dependent changes to the overall response that complicate data analysis. However, our data also suggest these nonlinearities might be advantageous to in vivo imaging, in that different types of melanins have different nonlinear responses. Therefore, methods to separate linear from nonlinear components in transient absorption measurements might provide additional information to aid in the diagnosis of melanoma. We will discuss numerical methods for analyzing the various nonlinear contributions to pump-probe signals, with the ultimate objective of real time analysis using digital signal processing techniques. To that end, we have replaced the lock-in amplifier in our pump-probe microscope with a high-speed data acquisition board, and reprogrammed the coprocessor field-programmable gate array (FPGA) to perform lock-in detection. The FPGA lock-in offers better performance than the commercial instrument, in terms of both signal to noise ratio and speed. In addition, the flexibility of the digital signal processing approach enables demodulation of more complicated waveforms, such as spread-spectrum sequences, which has the potential to accelerate microscopy methods that rely on slow relaxation phenomena, such as photo-thermal and phosphorescence lifetime imaging.

  12. Synthesis of Ag-ZnO with multiple rods (multipods) morphology and its application in the simultaneous photo-catalytic degradation of methyl orange and methylene blue.

    PubMed

    Arab Chamjangali, M; Bagherian, G; Javid, A; Boroumand, S; Farzaneh, N

    2015-11-05

    In this study, the photo-decolorization of a mixture of methylene blue (MB) and methyl orange (MO) was investigated using Ag-ZnO multipods. The photo-catalyst used, ZnO multipods, was successfully synthesized. The surface of ZnO microstructure was modified by deposition of different amounts of Ag nanoparticles (Ag NPs) using the photo-reduction method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis and atomic absorption spectroscopy. The photo-catalytic efficiency of Ag-ZnO is mainly controlled by the amount of Ag NPs deposited on the ZnO surface. The results obtained suggest that Ag-ZnO containing 6.5% Ag NPs, has the highest photo-catalytic performance in the simultaneous photo-degradation of dyes at a shorter time. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Thermal Cycling of Thermal Control Paints on Carbon-Carbon and Carbon-Polyimide Composites

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    2006-01-01

    Carbon-carbon composites and carbon-polyimide composites are being considered for space radiator applications owing to their light weight and high thermal conductivity. For those radiator applications where sunlight will impinge on the surface, it will be necessary to apply a white thermal control paint to minimize solar absorptance and enhance infrared emittance. Several currently available white thermal control paints were applied to candidate carbon-carbon and carbon-polyimide composites and were subjected to vacuum thermal cycling in the range of -100 C to +277 C. The optical properties of solar absorptance and infrared emittance were evaluated before and after thermal cycling. In addition, adhesion of the paints was evaluated utilizing a tape test. The test matrix included three composites: resin-derived carbon-carbon and vapor infiltrated carbon-carbon, both reinforced with pitch-based P-120 graphite fibers, and a polyimide composite reinforced with T-650 carbon fibers, and three commercially available white thermal control paints: AZ-93, Z-93-C55, and YB-71P.

  14. Excitation Light Dose Engineering to Reduce Photo-bleaching and Photo-toxicity

    PubMed Central

    Boudreau, Colton; Wee, Tse-Luen (Erika); Duh, Yan-Rung (Silvia); Couto, Melissa P.; Ardakani, Kimya H.; Brown, Claire M.

    2016-01-01

    It is important to determine the most effective method of delivering light onto a specimen for minimal light induced damage. Assays are presented to measure photo-bleaching of fluorophores and photo-toxicity to living cells under different illumination conditions. Turning the light off during part of the experimental time reduced photo-bleaching in a manner proportional to the time of light exposure. The rate of photo-bleaching of EGFP was reduced by 9-fold with light pulsing on the micro-second scale. Similarly, in living cells, rapid line scanning resulted in reduced cell stress as measured by mitochondrial potential, rapid cell protrusion and reduced cell retraction. This was achieved on a commercial confocal laser scanning microscope, without any compromise in image quality, by using rapid laser scan settings and line averaging. Therefore this technique can be implemented broadly without any software or hardware upgrades. Researchers can use the rapid line scanning option to immediately improve image quality on fixed samples, reduce photo-bleaching for large high resolution 3D datasets and improve cell health in live cell experiments. The assays developed here can be applied to other microscopy platforms to measure and optimize light delivery for minimal sample damage and photo-toxicity. PMID:27485088

  15. Excitation Light Dose Engineering to Reduce Photo-bleaching and Photo-toxicity.

    PubMed

    Boudreau, Colton; Wee, Tse-Luen Erika; Duh, Yan-Rung Silvia; Couto, Melissa P; Ardakani, Kimya H; Brown, Claire M

    2016-08-03

    It is important to determine the most effective method of delivering light onto a specimen for minimal light induced damage. Assays are presented to measure photo-bleaching of fluorophores and photo-toxicity to living cells under different illumination conditions. Turning the light off during part of the experimental time reduced photo-bleaching in a manner proportional to the time of light exposure. The rate of photo-bleaching of EGFP was reduced by 9-fold with light pulsing on the micro-second scale. Similarly, in living cells, rapid line scanning resulted in reduced cell stress as measured by mitochondrial potential, rapid cell protrusion and reduced cell retraction. This was achieved on a commercial confocal laser scanning microscope, without any compromise in image quality, by using rapid laser scan settings and line averaging. Therefore this technique can be implemented broadly without any software or hardware upgrades. Researchers can use the rapid line scanning option to immediately improve image quality on fixed samples, reduce photo-bleaching for large high resolution 3D datasets and improve cell health in live cell experiments. The assays developed here can be applied to other microscopy platforms to measure and optimize light delivery for minimal sample damage and photo-toxicity.

  16. Photo- and electroluminescence of new organic semiconductors

    NASA Astrophysics Data System (ADS)

    Samsonova, L. G.; Degtyarenko, K. M.; Gadirov, R. M.; Odod, A. V.; Kopylova, T. N.; Begimova, A.; Krasnikova, S. S.; Yakuschenko, I. K.; Gadomsky, S. Y.; Kaplunov, M. G.

    2018-04-01

    The results of investigation of the luminescence under photo- and electroexcitation for four new compounds are presented. The spectral properties and photoluminescence are studied in ethanol, chloroform solutions and in films formed by thermovacuum deposition (TVD). The phosphorescence of compounds is investigated in ethanol at 77K temperature. The phosphorescence times of molecules are given. The electroluminescence is obtained in multilayered structure ITO/PEDOT/NPD/L /Ca/Al. It is shown, that spectral region of the photoluminescence of TVD films and electroluminescence coincide. Relations of electroluminescence efficiency with molecule structure, photoluminescence quantum yield and possibility of thermally activated delayed fluorescence are discussed.

  17. High pressure chemistry of red phosphorus by photo-activated simple molecules

    NASA Astrophysics Data System (ADS)

    Ceppatelli, M.; Fanetti, S.; Bini, R.; Caporali, M.; Peruzzini, M.

    2014-05-01

    High pressure (HP) is very effective in reducing intermolecular distances and inducing unexpected chemical reactions. In addition the photo-activation of the reactants in HP conditions can lead to very efficient and selective processes. The chemistry of phosphorus is currently based on the white molecular form. The red polymeric allotrope, despite more stable and much less toxic, has not attracted much attention so far. However, switching from the white to the red form would benefit any industrial procedure, especially from an environmental point of view. On the other side, water and ethanol are renewable, environmental friendly and largely available molecules, usable as reactants and photo-activators in HP conditions. Here we report a study on the HP photo-induced reactivity of red phosphorus with water and ethanol, showing the possibility of very efficient and selective processes, leading to molecular hydrogen and valuable phosphorus compounds. The reactions have been studied by means of FTIR and Raman spectroscopy and pressure has been generated using membrane Diamond (DAC) and Sapphire (SAC) anvil cells. HP reactivity has been activated by the two-photon absorption of near-UV wavelengths and occurred in total absence of solvents, catalysts and radical initiators, at room T and mild pressure conditions (0.2-1.5 GPa).

  18. Kodak's Photo CD and Proposed Photo YCC Color Standard.

    ERIC Educational Resources Information Center

    Urrows, Henry; Urrows, Elizabeth

    1991-01-01

    Describes new technology being developed by Eastman Kodak for storing 35mm color photos on compact disk (CD) and discusses its applications for desktop publishing. Benefits of photo CD and costs are examined, a proposed universal color standard that is an improved way to represent color digitally is explained, and software is discussed. (LRW)

  19. Highly directional thermal emitter

    DOEpatents

    Ribaudo, Troy; Shaner, Eric A; Davids, Paul; Peters, David W

    2015-03-24

    A highly directional thermal emitter device comprises a two-dimensional periodic array of heavily doped semiconductor structures on a surface of a substrate. The array provides a highly directional thermal emission at a peak wavelength between 3 and 15 microns when the array is heated. For example, highly doped silicon (HDSi) with a plasma frequency in the mid-wave infrared was used to fabricate nearly perfect absorbing two-dimensional gratings structures that function as highly directional thermal radiators. The absorption and emission characteristics of the HDSi devices possessed a high degree of angular dependence for infrared absorption in the 10-12 micron range, while maintaining high reflectivity of solar radiation (.about.64%) at large incidence angles.

  20. Insulin fibrillation and protein design: topological resistance of single-chain analogs to thermal degradation with application to a pump reservoir.

    PubMed

    Phillips, Nelson B; Whittaker, Jonathan; Ismail-Beigi, Faramarz; Weiss, Michael A

    2012-03-01

    Insulin is susceptible to thermal fibrillation, a misfolding process that leads to nonnative cross-β assembly analogous to pathological amyloid deposition. Pharmaceutical formulations are ordinarily protected from such degradation by sequestration of the susceptible monomer within native protein assemblies. With respect to the safety and efficacy of insulin pumps, however, this strategy imposes an intrinsic trade-off between pharmacokinetic goals (rapid absorption and clearance) and the requisite physical properties of a formulation (prolonged shelf life and stability within the reservoir). Available rapid-acting formulations are suboptimal in both respects; susceptibility to fibrillation is exacerbated even as absorption is delayed relative to the ideal specifications of a closed-loop system. To circumvent this molecular trade-off, we exploited structural models of insulin fibrils and amyloidogenic intermediates to define an alternative protective mechanism. Single-chain insulin (SCI) analogs were shown to be refractory to thermal fibrillation with maintenance of biological activity for more than 3 months under conditions that promote the rapid fibrillation and inactivation of insulin. The essential idea exploits an intrinsic incompatibility between SCI topology and the geometry of cross-β assembly. A peptide tether was thus interposed between the A- and B-chains whose length was (a) sufficiently long to provide the "play" needed for induced fit of the hormone on receptor binding and yet (b) sufficiently short to impose a topological barrier to fibrillation. Our findings suggest that ultrastable monomeric SCI analogs may be formulated without protective self-assembly and so permit simultaneous optimization of pharmacokinetics and reservoir life. © 2012 Diabetes Technology Society.

  1. Investigating plausible mechanisms for the photo-induced partial unfolding of a globular protein

    NASA Astrophysics Data System (ADS)

    Parker, James E.

    Two hypotheses are proposed to explain the photo-induced unfolding of β-lactoglobulin (BLG) that occurs when non-covalently bound to a dye molecule, meso-tetrakis (p-sulfonatophenyl) porphyrin (TSPP), and illuminated by a laser in the post-Tanford transition configuration. The first involves a photo-induced electron transfer from the porphyrin to the protein. The second involves the production of kynurenine by singlet oxygen that is generated during photo-excitation of the porphyrin. To evaluate these hypotheses, a series of computational and experimental results have been combined to establish the physical state of the BLG-TSPP complex and to estimate the likelihood of a post-irradiation event to initiate the partial unfolding. Determining the binding site location is crucial to establish the position of the photo-induced events and the likely end-product. A study of the vibronic state of the BLG-TSPP complex using resonant Raman and absorption spectroscopy coupled with density functional theory (DFT) and docking simulations is used to estimate the location of the binding site. Once the binding site is found, molecular dynamics simulations of the post-irradiation event relaxations in the protein are used to estimate the resulting secondary structure. This structure is compared to experimental estimates of the secondary structure of the unfolded protein to determine which hypothesis is the most likely mechanism to explain the unfolding.

  2. Surface chemistry of Au/TiO2: Thermally and photolytically activated reactions

    NASA Astrophysics Data System (ADS)

    Panayotov, Dimitar A.; Morris, John R.

    2016-03-01

    The fascinating particle size dependence to the physical, photophysical, and chemical properties of gold has motivated thousands of studies focused on exploring the ability of supported gold nanoparticles to catalyze chemical transformations. In particular, titanium dioxide-supported gold (Au/TiO2) nanoparticles may provide the right combination of electronic structure, structural dynamics, and stability to affect catalysis in important practical applications from environmental remediation to selective hydrogenation to carbon monoxide oxidation. Harnessing the full potential of Au/TiO2 will require a detailed atomic-scale understanding of the thermal and photolytic processes that accompany chemical conversion. This review describes some of the unique properties exhibited by particulate gold before delving into how those properties affect chemistry on titania supports. Particular attention is given first to thermally driven reactions on single crystal system. This review then addresses nanoparticulate samples in an effort begin to bridge the so-called materials gap. Building on the foundation provided by the large body of work in the field of thermal catalysis, the review describes new research into light-driven catalysis on Au/TiO2. Importantly, the reader should bear in mind throughout this review that thermal chemistry and thermal effects typically accompany photochemistry. Distinguishing between thermally-driven stages of a reaction and photo-induced steps remains a significant challenge, but one that experimentalists and theorists are beginning to decipher with new approaches. Finally, a summary of several state-of-the-art studies describes how they are illuminating new frontiers in the quest to exploit Au/TiO2 as an efficient catalyst and low-energy photocatalyst.

  3. Meningococcus Disease Photos

    MedlinePlus

    ... of hands and lower extremities due to meningococcemia http://www.vaccineinformation.org/photos/menicdc001.jpg Courtesy Centers ... female with gangrene of feet due to meningococcemia http://www.vaccineinformation.org/photos/menicdc002.jpg Courtesy Centers ...

  4. The Lattice and Thermal Radiation Conductivity of Thermal Barrier Coatings: Models and Experiments

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Spuckler, Charles M.

    2010-01-01

    The lattice and radiation conductivity of ZrO2-Y2O3 thermal barrier coatings was evaluated using a laser heat flux approach. A diffusion model has been established to correlate the coating apparent thermal conductivity to the lattice and radiation conductivity. The radiation conductivity component can be expressed as a function of temperature, coating material scattering, and absorption properties. High temperature scattering and absorption of the coating systems can be also derived based on the testing results using the modeling approach. A comparison has been made for the gray and nongray coating models in the plasma-sprayed thermal barrier coatings. The model prediction is found to have a good agreement with experimental observations.

  5. Unsteady Sisko magneto-nanofluid flow with heat absorption and temperature dependent thermal conductivity: A 3D numerical study

    NASA Astrophysics Data System (ADS)

    Khan, Masood; Ahmad, Latif; Gulzar, M. Mudassar

    2018-03-01

    The impact of temperature dependent thermal conductivity and convective surface conditions on unsteady 3D Sisko nanofluid flow over a stretching surface is studied in the presence of heat generation/absorption and magnetic field. The numerical solution of nonlinear coupled equations has been carried out to explore the properties of different physical profiles of the fluid flow with varying of parameters. Specifically, the application of generalized Biot numbers and heat generation/absorption parameter in the sketching of temperature and concentration profiles are explored. The effect of all three parameters is noticed in the increasing order for shear thinning (0 < n < 1) and for shear thickening (n > 1) fluids. Moreover, the influence of Biot number γ1 on heat and mass transfer rates, are found in the enhancement and diminishing conducts respectively, in both cases of shear thinning as well as shear thickening fluids and a reverse trend is observed with the variation of Biot number γ2 . Additionally, the present results are validated through skin friction, heat and mass transfer rate values with the comparable values in the existing previous values.

  6. Synthesis and characterization of a new photo-crosslinkable glycol chitosan thermogel for biomedical applications.

    PubMed

    Cho, Ik Sung; Cho, Myeong Ok; Li, Zhengzheng; Nurunnabi, Md; Park, Sung Young; Kang, Sun-Woong; Huh, Kang Moo

    2016-06-25

    The major limitations of typical thermogelling polymers for practical applications are low gel stability and weak mechanical properties under physiological conditions. In this study, we have synthesized a new polysaccharide-based thermogelling polymer that can be photo-crosslinked by UV irradiation to form a mechanically resilient and elastic hydrogel. Methacrylated hexanoyl glycol chitosan (M-HGC), was synthesized by a series of chemical modifications, N-hexanoylation and N-methacrylation, of glycol chitosan (GC). Various M-HGC polymers with different methacryl group contents were synthesized and their thermogelling and photo-crosslinkable properties were evaluated. The M-HGCs demonstrated a thermo-reversible sol-gel transition behavior in aqueous solutions. The thermally-induced hydrogels could be chemically crosslinked by UV-triggered photo-crosslinking. From the cytotoxicity studies using MTT and the live/dead assay, the M-HGC hydrogels showed non-cytotoxicity. These photo-crosslinkable thermogelling M-HGC polymers may hold great promises for various biomedical applications, such as an injectable delivery system and 3D cell culture. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. CONSTRUCTION PROGRESS PHOTO OF REMOTE ANALYTICAL FACILITY (CPP627). INL PHOTO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONSTRUCTION PROGRESS PHOTO OF REMOTE ANALYTICAL FACILITY (CPP-627). INL PHOTO NUMBER NRTS-54-12124. Unknown Photographer, 9/21/1954 - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

  8. Probabilistic graphlet transfer for photo cropping.

    PubMed

    Zhang, Luming; Song, Mingli; Zhao, Qi; Liu, Xiao; Bu, Jiajun; Chen, Chun

    2013-02-01

    As one of the most basic photo manipulation processes, photo cropping is widely used in the printing, graphic design, and photography industries. In this paper, we introduce graphlets (i.e., small connected subgraphs) to represent a photo's aesthetic features, and propose a probabilistic model to transfer aesthetic features from the training photo onto the cropped photo. In particular, by segmenting each photo into a set of regions, we construct a region adjacency graph (RAG) to represent the global aesthetic feature of each photo. Graphlets are then extracted from the RAGs, and these graphlets capture the local aesthetic features of the photos. Finally, we cast photo cropping as a candidate-searching procedure on the basis of a probabilistic model, and infer the parameters of the cropped photos using Gibbs sampling. The proposed method is fully automatic. Subjective evaluations have shown that it is preferred over a number of existing approaches.

  9. Photo dynamics of BLUF domain mutant H44R of AppA from Rhodobacter sphaeroides

    NASA Astrophysics Data System (ADS)

    Zirak, P.; Penzkofer, A.; Hegemann, P.; Mathes, T.

    2007-05-01

    The photo-cycle dynamics of the H44R mutant of the BLUF domain of the transcriptional anti-repressor protein AppA (AppA-H44R) from the non-sulfur anoxyphototropic purple bacterium Rhodobacter sphaeroides is studied in order to gain information on the involvement of His44 in the photo-cyclic mechanism of the AppA BLUF domain and to add information to the involved processes. The amino acid residue histidine at position 44 is replaced by arginine. A 12 nm red-shifted signalling state is formed upon blue-light excitation, while in wild-type AppA (AppA-wt) the red-shift is 16 nm. The recovery to the receptor dark state is approximately a factor of 2.5 faster ( τrec ≈ 6.5 min) than the recovery of the wild-type counterpart. Extended light exposure of the mutant causes photo-degradation of flavin (mainly free flavin conversion to lumichrome and re-equilibration between free and non-covalently bound flavin) and protein aggregation (showing up as light scattering). No photo-degradation was observed for AppA-wt. The quantum efficiency of signalling-state formation determined by intensity dependent absorption measurements is found to be ϕs ≈ 0.3 (for AppA-wt: ϕs ≈ 0.24). A two-component single-exponential fluorescence relaxation was observed, which is interpreted as fast fluorescence quenching to an equilibrium value by photo-induced electron transfer followed by slower fluorescence decay due to charge recombination. Based on the experimental findings, an extended photo-cycle model for BLUF domains is proposed.

  10. Effect of plasma nitriding on the structural stability and hydrogen absorption capability of Pd-coated Nb during thermal treatment

    NASA Astrophysics Data System (ADS)

    Ohtsu, Naofumi; Kozuka, Taro; Shibata, Yuga; Yamane, Misao

    2017-11-01

    Plasma nitriding was explored for improving the thermal stability of a composite hydrogen permeable membrane comprising a Pd coating on Nb substrate. A NbN intermediate layer was formed on the Nb substrate, and the progress of interdiffusion and deterioration of hydrogen absorption behavior after a thermal treatment at 573 and 773 K, respectively, were investigated. The intermediate layer significantly suppressed the interdiffusion between the coating and the substrate. Furthermore, an increase in the NbN concentration of the intermediate layer enhanced the suppression efficiency. However, the hydrogen permeability of the intermediate layer was significantly low, and hence, an increase in NbN concentration further decreased the hydrogen permeability. We concluded that the nitride layer with a high NbN content was unsuitable as an intermediate layer owing to its low hydrogen permeability, while the partial nitride layer with a low NbN content was inefficient in suppressing the interdiffusion.

  11. Measurement of laser power for photo-triggered drug delivery in vivo

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, R.; Zhang, X. L.; Liu, F.

    Thus far, despite many investigations have been carried out for photo-triggered drug delivery systems, most of them suffer from an intrinsic drawback of without real-time monitoring mechanism. Incident intensity of light is a feasible parameter to monitor the drug release profiles. However, it is difficult to measure the incident laser power irradiated onto the photo-triggered carriers in drug delivery systems during in vivo therapy. We design an online measurement method based on the fluorescence intensity ratio (FIR) technique through upconversion nanoparticles. FIR value varies with temperature of sample due to the thermal effect induced by the incident laser, which validatesmore » the laser power measurement. Effects of rare earth doping concentration, as well as experimental conditions including laser spots and wavelengths on the measurement behavior were also investigated.« less

  12. Improved Photo-Detection Using Zigzag TiO2 Nanostructures as an Active Medium.

    PubMed

    Tiwari, A K; Mondal, A; Mahajan, B K; Choudhuri, B; Goswami, T; Sarkar, M B; Chakrabartty, S; Ngangbam, C; Saha, S

    2015-07-01

    Zigzag TiO2 nanostructures were fabricated using oblique angle deposition technique. The field emission gun-scanning electron microscope (FEG-SEM) image shows that the TiO2 zigzag nanostructures were ~500 nm in length. Averagely two times enhanced UV-Vis absorption was recorded for zigzag structure compared to perpendicular TiO2 nanowires. The main band transition was observed at ~3.4 eV. The zigzag TiO2 exhibited high turn on voltage (+11 V) than that of nanowire (+2 V) detector under dark which were reduced to +0.2 V and +1.0 V under white light illumination, respectively. A maximum ~6 fold photo-responsivity was observed for the zigzag TiO2 compared with nanowire device at + 1.0 V applied potential. The maximum photo-responsivity of 0.36 A/W at 370 nm was measured for the zigzag TiO2 detector. The TiO2 zigzag detector showed slow response with rise time of 10.2 s and fall time of 10.3 s respectively. The UV (370 nm) to visible (450 nm) wavelength rejection ratio of photo-responsivity was recorded ~4 times for the detector.

  13. Pi-pi* orbital transitions and photo-degeneracy of C.acuminata sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Abodunrin, T.; Boyo, A.; Usikalu, M.; Obafemi, L.; Oladapo, O.; Kotsedi, L.; Yenus, Z.; Maaza, M.

    2017-04-01

    Dye-sensitized solar cells (DSSCs) have acquired great prominence as favourable low-cost photovoltaics due to their ease of fabrication, all- year -availability, ease of obtaining raw materials and adjustable optical properties like transparency and colour. These advantages coupled with the ability to work under poor lighting makes them a suitable candidate for next generation of research. In this research, C.acuminata-sensitized photo anodes play an important role for achieving high performance since the porous metal oxide films provide a large specific surface area for dye loading and the possibility to extend the absorption threshold of past studies of sensitizers. The doctor blade method and high-temperature sintering were some of the methods used in the fabrication of the photo anode. A study of the performance of the C.acuminata-DSSCs with four different electrolyte sensitizers based on iodide redox mediator is determined. The result is DSSCs that exhibit a maximum power output of 39.37 W, fill factor of 0.7 and a power conversion efficiency of 0.6% under unfavourable sunlight intensity conditions and photo-degradation of about 37.5 % in absorbance after 425 suns.

  14. Thermal radiation and heat generation/absorption aspects in third grade magneto-nanofluid over a slendering stretching sheet with Newtonian conditions

    NASA Astrophysics Data System (ADS)

    Qayyum, Sajid; Hayat, Tasawar; Alsaedi, Ahmed

    2018-05-01

    Mathematical modeling for magnetohydrodynamic (MHD) radiative flow of third grade nano-material bounded by a nonlinear stretching sheet with variable thickness is introduced. The sheet moves with nonlinear velocity. Definitions of thermal radiation and heat generation/absorption are utilized in the energy expression. Intention in present investigation is to develop a model for nanomaterial comprising Brownian motion and thermophoresis phenomena. Newtonian conditions for heat and mass species are imposed. Governing equations of the locally similar flow are attempted through a homotopic technique and behaviors of involved variables on the flow fields are displayed graphically. It is revealed that increasing values of thermal conjugate variable corresponds to high temperature. Numerical investigation are explored to obtain the results of skin friction coefficient and local Nusselt and Sherwood numbers. It is revealed that velocity field reduces in the frame of magnetic variable while reverse situation is observed due to mixed convection parameter. Here qualitative behaviors of thermal field and heat transfer rate are opposite for thermophoresis variable. Moreover nanoparticle concentration and local Sherwood number via Brownian motion parameter are opposite.

  15. CONSTRUCTION PROGRESS PHOTO OF REMOTE ANALYTICAL FACILITY (CPP627). INL PHOTO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONSTRUCTION PROGRESS PHOTO OF REMOTE ANALYTICAL FACILITY (CPP-627). INL PHOTO NUMBER NRTS-54-12573. R.G. Larsen, Photographer, 10/20/1954 - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

  16. Synthesis and characterization of gold/water nanofluids suitable for thermal applications produced by femtosecond laser radiation

    NASA Astrophysics Data System (ADS)

    Mondragón, Rosa; Torres-Mendieta, Rafael; Meucci, Marco; Mínguez-Vega, Gladys; Enrique Juliá, J.; Sani, Elisa

    2016-07-01

    A laser-based "green" synthesis of nanoparticles (NPs) was used to manufacture gold NPs in water. The light source is a Ti:Sapphire laser with 30 fs FWHM pulses, 800 nm mean wavelength, and 1 kHz repetition rate. The method involves two stages: (1) pulsed laser ablation in liquids and (2) photo-fragmentation (PF). Highly pure and well-dispersed NPs with a diameter of 18.5 nm that can be stored at room temperature without showing any agglomeration over a period of at least 3 months were produced without the need to use any stabilizer. Transmittance spectra, extinction coefficient, NPs agglomeration dynamics, and thermal conductivity of the nanofluids obtained were analyzed before and after being submitted to thermal cycling and compared to those obtained for commercial gold/water suspensions. Optical properties have also been investigated, showing no substantial differences for thermal applications between NPs produced by the laser ablation and PF technique and commercial NPs. Therefore, nanofluids produced by this technique can be used in thermal applications, which are foreseen for conventional nanofluids, e.g., heat transfer enhancement and solar radiation direct absorption, but offering the opportunity to produce them in situ in almost any kind of fluid without the production of any chemical waste.

  17. Photo-crosslinkable polymers for fabrication of photonic multilayer sensors

    NASA Astrophysics Data System (ADS)

    Chiappelli, Maria; Hayward, Ryan C.

    2013-03-01

    We have used photo-crosslinkable polymers to fabricate photonic multilayer sensors. Benzophenone is utilized as a covalently incorporated pendent photo-crosslinker, providing a convenient means of fabricating multilayer films by sequential spin-coating and crosslinking processes. Colorimetric temperature sensors were designed from thermally-responsive, low-refractive index poly(N-isopropylacrylamide) (PNIPAM) and high-refractive index poly(para-methyl styrene) (P pMS). Copolymer chemistries and layer thicknesses were selected to provide robust multilayer sensors which show color changes across nearly the full visible spectrum due to changes in temperature of the hydrated film stack. We have characterized the uniformity and interfacial broadening within the multilayers, the kinetics of swelling and de-swelling, and the reversibility over multiple hydration/dehydration cycles. We also describe how the approach can be extended to alternative sensor designs through the ability to tailor each layer independently, as well as to additional stimuli by selecting alternative copolymer chemistries.

  18. The Effect of Simulated Lunar Dust on the Absorptivity, Emissivity, and Operating Temperature on AZ-93 and Ag/FEP Thermal Control Surfaces

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Siamidis, John; Panko, Scott R.; Rogers, Kerry J.; Larkin, Elizabeth M. G.

    2008-01-01

    JSC-1AF lunar simulant has been applied to AZ-93 and AgFEP thermal control surfaces on aluminum or composite substrates in a simulated lunar environment. The temperature of these surfaces was monitored as they were heated with a solar simulator and cooled in a 30 K coldbox. Thermal modeling was used to determine the absorptivity ( ) and emissivity ( ) of the thermal control surfaces in both their clean and dusted states. Then, a known amount of power was applied to the samples while in the coldbox and the steady state temperatures measured. It was found that even a submonolayer of simulated lunar dust can significantly degrade the performance of both white paint and second-surface mirror type thermal control surfaces under these conditions. Contrary to earlier studies, dust was found to affect as well as . Dust lowered the emissivity by as much as 16 percent in the case of AZ-93, and raised it by as much as 11 percent in the case of AgFEP. The degradation of thermal control surface by dust as measured by / rose linearly regardless of the thermal control coating or substrate, and extrapolated to degradation by a factor 3 at full coverage by dust. Submonolayer coatings of dust were found to not significantly change the steady state temperature at which a shadowed thermal control surface will radiate.

  19. Thermal modeling of a secondary concentrator integrated with an open direct-absorption molten-salt volumetric receiver in a beam-down tower system

    NASA Astrophysics Data System (ADS)

    Lahlou, Radia; Armstrong, Peter; Grange, Benjamin; Almheiri, Saif; Calvet, Nicolas; Slocum, Alexander; Shamim, Tariq

    2016-05-01

    An upward-facing three-dimensional secondary concentrator, herein termed Final Optical Element (FOE), is designed to be used in a beam-down tower in combination with an open volumetric direct-absorption molten-salt receiver tank acting simultaneously as a thermal energy storage system. It allows reducing thermal losses from the open receiver by decreasing its aperture area while keeping minimal spillage losses. The FOE is exposed to high solar fluxes, a part of which is absorbed by its reflector material, leading to material degradation by overheating. Consequently, the FOE may require active cooling. A thermal model of the FOE under passive cooling mechanism is proposed as a first step to evaluate its sensitivity to some design parameters. Then, it will be used to evaluate the requirements for the active cooling system. The model provides insights on the FOE thermal behavior and highlights the effectiveness of a design modification on passive cooling enhancement. First prototype tests under reduced flux and with no active cooling will be used for model adjustment.

  20. Characterization of laser damage performance of fused silica using photothermal absorption technique

    NASA Astrophysics Data System (ADS)

    Wan, Wen; Shi, Feng; Dai, Yifan; Peng, Xiaoqiang

    2017-06-01

    The subsurface damage and metal impurities have been the main laser damage precursors of fused silica while subjected to high power laser irradiation. Light field enhancement and thermal absorption were used to explain the appearance of damage pits while the laser energy is far smaller than the energy that can reach the intrinsic threshold of fused silica. For fused silica optics manufactured by magnetorheological finishing or advanced mitigation process, no scratch-related damage site occurs can be found on the surface. In this work, we implemented a photothermal absorption technique based on thermal lens method to characterize the subsurface defects of fused silica optics. The pump beam is CW 532 nm wavelength laser. The probe beam is a He-Ne laser. They are collinear and focused through the same objective. When pump beam pass through the sample, optical absorption induces the local temperature rise. The lowest absorptance that we can detect is about the order of magnitude of 0.01 ppm. When pump beam pass through the sample, optical absorption induces the local temperature rise. The photothermal absorption value of fused silica samples range from 0.5 to 10 ppm. The damage densities of the samples were plotted. The damage threshold of samples at 8J/cm2 were gived to show laser damage performance of fused silica.The results show that there is a strong correlation between the thermal absorption and laser damage density. The photothermal absorption technique can be used to predict and evaluate the laser damage performance of fused silica optics.

  1. Non-degenerate two-photon absorption in silicon waveguides. Analytical and experimental study

    DOE PAGES

    Zhang, Yanbing; Husko, Chad; Lefrancois, Simon; ...

    2015-06-22

    We theoretically and experimentally investigate the nonlinear evolution of two optical pulses in a silicon waveguide. We provide an analytic solution for the weak probe wave undergoing non-degenerate two-photon absorption (TPA) from the strong pump. At larger pump intensities, we employ a numerical solution to study the interplay between TPA and photo-generated free carriers. We develop a simple and powerful approach to extract and separate out the distinct loss contributions of TPA and free-carrier absorption from readily available experimental data. Our analysis accounts accurately for experimental results in silicon photonic crystal waveguides.

  2. Conjugated polymer and drug co-encapsulated nanoparticles for Chemo- and Photo-thermal Combination Therapy with two-photon regulated fast drug release

    NASA Astrophysics Data System (ADS)

    Yuan, Youyong; Wang, Zuyong; Cai, Pingqiang; Liu, Jie; Liao, Lun-De; Hong, Minghui; Chen, Xiaodong; Thakor, Nitish; Liu, Bin

    2015-02-01

    The spatial-temporal synchronization of photothermal therapy and chemotherapy is highly desirable for an efficient cancer treatment with synergistic effect. Herein, we developed a chemotherapeutic drug doxorubicin (DOX) and photothermal conjugated polymer (CP) co-loaded nanoplatform using a near-infrared (NIR) laser responsive amphiphilic brush copolymer as the encapsulation matrix. The obtained nanoparticles (NPs) exhibit good monodispersity and excellent stability, which can efficiently convert laser energy into thermal energy for photothermal therapy. Moreover, the hydrophobic polymer matrix bearing a number of 2-diazo-1,2-naphthoquinones (DNQ) moieties could be transformed to a hydrophilic one upon NIR two-photon laser irradiation, which leads to fast drug release. Furthermore, the surface modification of the NPs with cyclic arginine-glycine-aspartic acid (cRGD) tripeptide significantly enhances the accumulation of the NPs within integrin αvβ3 overexpressed cancer cells. The half-maximal inhibitory concentration (IC50) of the combination therapy is 13.7 μg mL-1, while the IC50 for chemotherapy and photothermal therapy alone is 147.8 μg mL-1 and 36.2 μg mL-1, respectively. The combination index (C.I.) is 0.48 (<1), which indicates the synergistic effect for chemotherapy and PTT. These findings provide an excellent NIR laser regulated nanoplatform for combined cancer treatment with synergistic effect due to the synchronous chemo- and photo-thermal therapy.

  3. VOC removal and deodorization of effluent gases from an industrial plant by photo-oxidation, chemical oxidation, and ozonization.

    PubMed

    Domeño, Celia; Rodríguez-Lafuente, Angel; Martos, J M; Bilbao, Rafael; Nerín, Cristina

    2010-04-01

    The efficiency of photo-oxidation, chemical oxidation by sodium hypochlorite, and ozonization for the industrial-scale removal of volatile organic compounds (VOCs) and odors from gaseous emissions was studied by applying these treatments (in an experimental system) to substances passing through an emission stack of a factory producing maize derivatives. Absorption and ozonization were the most efficient treatment, removing 75% and 98% of VOCs, respectively, while photo-oxidation only removed about 59%. The emitted chemical compounds and odors were identified and quantified by gas chromatography-mass spectrometry (in full-scan mode). In addition to presenting the results, their implications for selecting optimal processes for treating volatile emissions are discussed.

  4. Formation of artificial pores in nano-TiO2 photo-electrode films using acetylene-black for high-efficiency, dye-sensitized solar cells

    PubMed Central

    Cho, Tae-Yeon; Han, Chi-Whan; Jun, Yongseok; Yoon, Soon-Gil

    2013-01-01

    Acetylene-black paste without a light scattering layer was applied to meso-porous TiO2 photo-electrode films with a crystalline framework, a low residual carbon, and a tunable morphological pore size. The thermal-treated TiO2 photo-electrode films had an increased acetylene-black concentration with an increase in artificial pores and a decrease in residual carbon. The performance of dye-sensitized solar cells (DSSCs) was enhanced by the use of the TiO2 photo-anode pastes at various acetylene-black concentrations. The photo-conversion efficiency of the DSSCs using TiO2 photo-electrode films with 1.5 wt% acetylene-black was enhanced from 7.98 (no acetylene-black) to 9.75% without the integration of a light- scattering layer. PMID:23511122

  5. Anomalous absorption of isolated silver nanoparticulate films in visible region of electromagnetic field.

    PubMed

    Kim, Sang Woo; Hui, Bang Jae; Bae, Dong-Sik

    2008-02-01

    Anomalous absorption of isolated silver nanoparticulate films with different morphological patterns prepared by the wet colloidal route and followed by thermal treatment were investigated. A polymer embedded silver nanoparticulate film thermally treated at 200 degrees C showed maximum absorbance at approximately 412 nm. The peak position of the surface plasmon band was slightly different but still consistent with theoretical prediction derived by the Mie theory. An isolated nanopariculate film thermally treated at 300 degrees C showed anomalous absorption. Its maximum absorption band was shifted to green regime of 506.9 nm and the bandwidth at half-maximum absorbance of the surface plasmon band was greatly broadened. The plasmon band and its bandwidth were much deviated compared to the theoretical prediction calculated for the silver nanoparticles in the surrounding medium of air and poly(vinyl pyrrolidone) or soda-lime-silica glass. Even though there was no significant growth of silver nanoparticles during thermal treatment at 300 degrees C, the anomalous absorption was observed. The anomalous absorption was not attributed to effects of particle shape and size but to effects of pores induced by development of a great number of pores in the nanoparticulate film. The anomalous absorption greatly decreased with increase in heating temperature from 400 degrees C to 500 degrees C. The extraordinary plasmon damping of the isolated film decreased and the plasmon absorption band was re-shifted to violet regime of 416 nm because of large decrease in size of particles with dramatic change of pore morphology from circular pores with rim to small continuous pores induced by spontaneous formation of new silver nanoparticles.

  6. An Innovative Strategy for Accurate Thermal Compensation of Gyro Bias in Inertial Units by Exploiting a Novel Augmented Kalman Filter

    PubMed Central

    Angrisani, Leopoldo; Simone, Domenico De

    2018-01-01

    This paper presents an innovative model for integrating thermal compensation of gyro bias error into an augmented state Kalman filter. The developed model is applied in the Zero Velocity Update filter for inertial units manufactured by exploiting Micro Electro-Mechanical System (MEMS) gyros. It is used to remove residual bias at startup. It is a more effective alternative to traditional approach that is realized by cascading bias thermal correction by calibration and traditional Kalman filtering for bias tracking. This function is very useful when adopted gyros are manufactured using MEMS technology. These systems have significant limitations in terms of sensitivity to environmental conditions. They are characterized by a strong correlation of the systematic error with temperature variations. The traditional process is divided into two separated algorithms, i.e., calibration and filtering, and this aspect reduces system accuracy, reliability, and maintainability. This paper proposes an innovative Zero Velocity Update filter that just requires raw uncalibrated gyro data as input. It unifies in a single algorithm the two steps from the traditional approach. Therefore, it saves time and economic resources, simplifying the management of thermal correction process. In the paper, traditional and innovative Zero Velocity Update filters are described in detail, as well as the experimental data set used to test both methods. The performance of the two filters is compared both in nominal conditions and in the typical case of a residual initial alignment bias. In this last condition, the innovative solution shows significant improvements with respect to the traditional approach. This is the typical case of an aircraft or a car in parking conditions under solar input. PMID:29735956

  7. An Innovative Strategy for Accurate Thermal Compensation of Gyro Bias in Inertial Units by Exploiting a Novel Augmented Kalman Filter.

    PubMed

    Fontanella, Rita; Accardo, Domenico; Moriello, Rosario Schiano Lo; Angrisani, Leopoldo; Simone, Domenico De

    2018-05-07

    This paper presents an innovative model for integrating thermal compensation of gyro bias error into an augmented state Kalman filter. The developed model is applied in the Zero Velocity Update filter for inertial units manufactured by exploiting Micro Electro-Mechanical System (MEMS) gyros. It is used to remove residual bias at startup. It is a more effective alternative to traditional approach that is realized by cascading bias thermal correction by calibration and traditional Kalman filtering for bias tracking. This function is very useful when adopted gyros are manufactured using MEMS technology. These systems have significant limitations in terms of sensitivity to environmental conditions. They are characterized by a strong correlation of the systematic error with temperature variations. The traditional process is divided into two separated algorithms, i.e., calibration and filtering, and this aspect reduces system accuracy, reliability, and maintainability. This paper proposes an innovative Zero Velocity Update filter that just requires raw uncalibrated gyro data as input. It unifies in a single algorithm the two steps from the traditional approach. Therefore, it saves time and economic resources, simplifying the management of thermal correction process. In the paper, traditional and innovative Zero Velocity Update filters are described in detail, as well as the experimental data set used to test both methods. The performance of the two filters is compared both in nominal conditions and in the typical case of a residual initial alignment bias. In this last condition, the innovative solution shows significant improvements with respect to the traditional approach. This is the typical case of an aircraft or a car in parking conditions under solar input.

  8. Synthesis of nanocrystalline α-Fe2O3 by using thermal oxidation of Fe Films

    NASA Astrophysics Data System (ADS)

    Fortas, G.; Saidoun, I.; Abboud, H.; Gabouze, N.; Haine, N.; Manseri, A.; Zergoug, M.; Menari, H.; Sam, S.; Cheraga, H.; Bozetine, I.

    2018-03-01

    α-Fe2O3 hematite films were prepared by thermal oxidation from Fe films electroplated on silicon. Electrodeposition of Fe thin films was carried out from a sulfate bath containing an ammonium chloride complexing agent. The electrochemical study was performed by cyclic voltammetry. The SEM analysis of the films obtained at a -1.3 V constant polarization shows dendritic grains in the form of islet. The DRX spectra exhibit characteristic iron peaks according to the face centered cubic (Fcc) structure. These samples were annealed. At a temperature of 650 ° C, a single iron oxide phase was well formed, with the hematite structure. The SEM photos show a well-assembled columnar structure with formation of nanowires at the surface of the deposit. The absorbance spectra reveal an absorption features in the ultraviolet range

  9. Stable azodye photo-alignment layer for liquid crystal devices achieved by "turning off" dye photosensitivity

    NASA Astrophysics Data System (ADS)

    McGinty, C.; Finnemeyer, V.; Reich, R.; Clark, H.; Berry, S.; Bos, P.

    2017-11-01

    We have previously proposed a low cost, versatile process for stabilizing azodye photo-alignment layers for liquid crystal devices by utilizing a surface localized reactive mesogen (RM) layer. The RM is applied by dissolving the monomer in a liquid crystal material prior to filling the cell. In this paper, we show the significant effect of azodye layer thickness on the long term stability of these alignment layers when exposed to polarized light. We demonstrate, surprisingly, that thin azodye layers (˜3 nm) provide improved stability over thicker (˜40 nm) layers. Using this process, we show cells which have been stable to exposure with polarized light through one month. Additionally, we demonstrate the use of a photo-alignment layer to align the liquid crystals that afterwards can be rendered insensitive to polarized light. This was accomplished by using the process described above with the additional step of eliminating the photosensitivity of the azodye layer through photo-bleaching; the result is an RM alignment layer that will be stable when exposed to polarized light in the dye absorption band.

  10. Photo-degradation of high efficiency fullerene-free polymer solar cells.

    PubMed

    Upama, Mushfika Baishakhi; Wright, Matthew; Mahmud, Md Arafat; Elumalai, Naveen Kumar; Mahboubi Soufiani, Arman; Wang, Dian; Xu, Cheng; Uddin, Ashraf

    2017-12-07

    Polymer solar cells are a promising technology for the commercialization of low cost, large scale organic solar cells. With the evolution of high efficiency (>13%) non-fullerene polymer solar cells, the stability of the cells has become a crucial parameter to be considered. Among the several degradation mechanisms of polymer solar cells, burn-in photo-degradation is relatively less studied. Herein, we present the first systematic study of photo-degradation of novel PBDB-T:ITIC fullerene-free polymer solar cells. The thermally treated and as-prepared PBDB-T:ITIC solar cells were exposed to continuous 1 sun illumination for 5 hours. The aged devices exhibited rapid losses in the short-circuit current density and fill factor. The severe short-circuit current and fill factor burn in losses were attributed to trap mediated charge recombination, as evidenced by an increase in Urbach energy for aged devices.

  11. Realistic absorption coefficient of ultrathin films

    NASA Astrophysics Data System (ADS)

    Cesaria, M.; Caricato, A. P.; Martino, M.

    2012-10-01

    Both a theoretical algorithm and an experimental procedure are discussed of a new route to determine the absorption/scattering properties of thin films deposited on transparent substrates. Notably, the non-measurable contribution of the film-substrate interface is inherently accounted for. While the experimental procedure exploits only measurable spectra combined according to a very simple algorithm, the theoretical derivation does not require numerical handling of the acquired spectra or any assumption on the film homogeneity and substrate thickness. The film absorption response is estimated by subtracting the measured absorption spectrum of the bare substrate from that of the film on the substrate structure but in a non-straightforward way. In fact, an assumption about the absorption profile of the overall structure is introduced and a corrective factor accounting for the relative film-to-substrate thickness. The method is tested on films of a well known material (ITO) as a function of the film structural quality and influence of the film-substrate interface, both deliberately changed by thickness tuning and doping. Results are found fully consistent with information obtained by standard optical analysis and band gap values reported in the literature. Additionally, comparison with a conventional method demonstrates that our route is generally more accurate even if particularly suited for very thin films.

  12. Dissipative structure in the photo-induced phase under steady light irradiation in the spin crossover complex.

    PubMed

    Nishihara, Taishi; Bousseksou, Azzdine; Tanaka, Koichiro

    2013-12-16

    We report the spatial and temporal dynamics of the photo-induced phase in the iron (II) spin crossover complex Fe(ptz)(6)(BF(4))(2) studied by image measurement under steady light irradiation and transient absorption measurement. The dynamic factors are derived from the spatial and temporal fluctuation of the image in the steady state under light irradiation between 65 and 100 K. The dynamic factors clearly indicate that the fluctuation has a resonant frequency that strongly depends on the temperature, and is proportional to the relaxation rate of the photo-induced phase. This oscillation of the speckle pattern under steady light irradiation is ascribed to the nonlinear interaction between the spin state and the lattice volume at the surface.

  13. Variable anodic thermal control coating on aluminum

    NASA Technical Reports Server (NTRS)

    Duckett, R. J.; Gilliland, C. S.

    1983-01-01

    A variable thermal control coating (modified chromic acid anodizing) has been developed to meet the needs for the thermal control of spacecraft. This coating, with controlled variable ranges of 0.10 to 0.72 thermal emittance and 0.2 to 0.4 solar absorptance, allows the user to select any value of thermal emittance and solar absorptance within the range specified and obtain both values within + or - 0.02. Preliminary solar stability has shown less than 15 percent degradation over 2000 hours of vacuum solar exposure. The technique has been determined to be sensitive to the parameters of voltage, rate of voltage application, time, temperature, acid concentration, and material pretreatment.

  14. Surface oxygen micropatterns on glow discharge polymer targets by photo irradiation

    DOE PAGES

    Reynolds, Hannah; Baxamusa, Salmaan; Haan, Steven W.; ...

    2016-02-24

    Recent simulations predict surface oxygen may be a significant source of disruptive perturbations in the implosion process of glow-discharge polymers (GDP) ablators at the National Ignition Facility. GDP material held in ambient atmospheric conditions showed an increase in mass when stored in light transparent containers, which suggests that photo exposure is a driving force for oxygen absorption. To investigate if surface oxygen is a contributing factor of disruptive perturbations during implosion, we developed a method to imprint a periodic micropattern of oxygen on the surface of GDP and used it to fabricate a flat sample for empirical testing.

  15. Face photo-sketch synthesis and recognition.

    PubMed

    Wang, Xiaogang; Tang, Xiaoou

    2009-11-01

    In this paper, we propose a novel face photo-sketch synthesis and recognition method using a multiscale Markov Random Fields (MRF) model. Our system has three components: 1) given a face photo, synthesizing a sketch drawing; 2) given a face sketch drawing, synthesizing a photo; and 3) searching for face photos in the database based on a query sketch drawn by an artist. It has useful applications for both digital entertainment and law enforcement. We assume that faces to be studied are in a frontal pose, with normal lighting and neutral expression, and have no occlusions. To synthesize sketch/photo images, the face region is divided into overlapping patches for learning. The size of the patches decides the scale of local face structures to be learned. From a training set which contains photo-sketch pairs, the joint photo-sketch model is learned at multiple scales using a multiscale MRF model. By transforming a face photo to a sketch (or transforming a sketch to a photo), the difference between photos and sketches is significantly reduced, thus allowing effective matching between the two in face sketch recognition. After the photo-sketch transformation, in principle, most of the proposed face photo recognition approaches can be applied to face sketch recognition in a straightforward way. Extensive experiments are conducted on a face sketch database including 606 faces, which can be downloaded from our Web site (http://mmlab.ie.cuhk.edu.hk/facesketch.html).

  16. Photo-dynamics of roseoflavin and riboflavin in aqueous and organic solvents

    NASA Astrophysics Data System (ADS)

    Zirak, P.; Penzkofer, A.; Mathes, T.; Hegemann, P.

    2009-03-01

    Roseoflavin (8-dimethylamino-8-demethyl- D-riboflavin) and riboflavin in aqueous and organic solvents are studied by optical absorption spectroscopy, fluorescence spectroscopy, and fluorescence decay kinetics. Solvent polarity dependent absorption shifts are observed. The fluorescence quantum yields are solvent dependent. For roseoflavin the fluorescence decay shows a bi-exponential dependence (ps to sub-ps time constant, and 100 ps to a few ns time constant). The roseoflavin photo-dynamics is explained in terms of fast intra-molecular charge transfer (diabatic electron transfer) from the dimethylamino electron donor group to the pteridin carbonyl electron acceptor followed by intra-molecular charge recombination. The fast fluorescence component is due to direct locally-excited-state emission, and the slow fluorescence component is due to delayed locally-excited-state emission and charge transfer state emission. The fluorescence decay of riboflavin is mono-exponential. The S 1-state potential energy surface is determined by vibronic relaxation and solvation dynamics due to excited-state dipole moment changes (adiabatic optical electron transfer).

  17. Ocean Thermal Energy.

    ERIC Educational Resources Information Center

    Berkovsky, Boris

    1987-01-01

    Describes Ocean Thermal Energy Conservation (OTEC) as a method for exploiting the temperature difference between warm surface waters of the sea and its cold depths. Argues for full-scale demonstrations of the technique for producing energy for coastal regions. (TW)

  18. High Ultraviolet Absorption in Colloidal Gallium Nanoparticles Prepared from Thermal Evaporation

    PubMed Central

    Bravo, Iria; Catalan-Gomez, Sergio; Vázquez, Luis; Lorenzo, Encarnación; Pau, Jose Luis

    2017-01-01

    New methods for the production of colloidal Ga nanoparticles (GaNPs) are introduced based on the evaporation of gallium on expendable aluminum zinc oxide (AZO) layer. The nanoparticles can be prepared in aqueous or organic solvents such as tetrahydrofuran in order to be used in different sensing applications. The particles had a quasi mono-modal distribution with diameters ranging from 10 nm to 80 nm, and their aggregation status depended on the solvent nature. Compared to common chemical synthesis, our method assures higher yield with the possibility of tailoring particles size by adjusting the deposition time. The GaNPs have been studied by spectrophotometry to obtain the absorption spectra. The colloidal solutions exhibit strong plasmonic absorption in the ultra violet (UV) region around 280 nm, whose width and intensity mainly depend on the nanoparticles dimensions and their aggregation state. With regard to the colloidal GaNPs flocculate behavior, the water solvent case has been investigated for different pH values, showing UV-visible absorption because of the formation of NPs clusters. Using discrete dipole approximation (DDA) method simulations, a close connection between the UV absorption and NPs with a diameter smaller than ~40 nm was observed. PMID:28684687

  19. Photo-Induced Click Chemistry for DNA Surface Structuring by Direct Laser Writing.

    PubMed

    Kerbs, Antonina; Mueller, Patrick; Kaupp, Michael; Ahmed, Ishtiaq; Quick, Alexander S; Abt, Doris; Wegener, Martin; Niemeyer, Christof M; Barner-Kowollik, Christopher; Fruk, Ljiljana

    2017-04-11

    Oligonucleotides containing photo-caged dienes were prepared and shown to react quantitatively in a light-induced Diels-Alder cycloaddition with functional maleimides in aqueous solution within minutes. Due to its high yield and fast rate, the reaction was exploited for DNA surface patterning with sub-micrometer resolution employing direct laser writing (DLW). Functional DNA arrays were written by direct laser writing (DLW) in variable patterns, which were further encoded with fluorophores and proteins through DNA directed immobilization. This mild and efficient light-driven platform technology holds promise for the fabrication of complex bioarrays with sub-micron resolution. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Numerical models to evaluate the temperature increase induced by ex vivo microwave thermal ablation.

    PubMed

    Cavagnaro, M; Pinto, R; Lopresto, V

    2015-04-21

    Microwave thermal ablation (MTA) therapies exploit the local absorption of an electromagnetic field at microwave (MW) frequencies to destroy unhealthy tissue, by way of a very high temperature increase (about 60 °C or higher). To develop reliable interventional protocols, numerical tools able to correctly foresee the temperature increase obtained in the tissue would be very useful. In this work, different numerical models of the dielectric and thermal property changes with temperature were investigated, looking at the simulated temperature increments and at the size of the achievable zone of ablation. To assess the numerical data, measurement of the temperature increases close to a MTA antenna were performed in correspondence with the antenna feed-point and the antenna cooling system, for increasing values of the radiated power. Results show that models not including the changes of the dielectric and thermal properties can be used only for very low values of the power radiated by the antenna, whereas a good agreement with the experimental values can be obtained up to 20 W if water vaporization is included in the numerical model. Finally, for higher power values, a simulation that dynamically includes the tissue's dielectric and thermal property changes with the temperature should be performed.

  1. Influence of PCMs in thermal insulation on thermal behaviour of building envelopes

    NASA Astrophysics Data System (ADS)

    Dydek, K.; Furmański, P.; Łapka, P.

    2016-09-01

    A model of heat transfer through a wall consisting of a layer of concrete and PCM enhanced thermal insulation is considered. The model accounts for heat conduction in both layers, thermal radiation and heat absorption/release due to phase change in the insulation as well as time variation in the ambient temperature and insolation. Local thermal equilibrium between encapsulated PCM and light-weight thermal insulation was assumed. Radiation emission, absorption and scattering were also accounted for in the model. Comparison of different cases of heat flow through the building envelope was carried out. These cases included presence or absence of PCM and thermal radiation in the insulation, effect of emissivity of the PCM microcapsules as well as an effect of solar radiation or its lack on the ambient side of the envelope. Two ways of the PCM distribution in thermal insulation were also considered. The results of simulations were presented for conditions corresponding to the mean summer and winter seasons in Warsaw. It was found that thermal radiation plays an important role in heat transfer through thermal insulation layer of the wall while the presence of the PCM in it significantly contributes to damping of temperature fluctuations and a decrease in heat fluxes flowing into or lost by the interior of the building. The similar effect was observed for a decrease in emissivity of the microcapsules containing PCM.

  2. Interlocked Photo-degradable Macrocycles Allow One-Off Photo-triggerable Gelation of Organo- and Hydrogelators.

    PubMed

    Tung, Shun-Te; Cheng, Hung-Te; Inthasot, Alex; Hsueh, Fang-Che; Gu, Ting-Jia; Yan, Pei-Cong; Lai, Chien-Chen; Chiu, Sheng-Hsien

    2018-02-01

    [2]Rotaxanes displaying one-off photo-triggerable gelation properties have been synthesized through the "clipping" of photo-degradable macrocycles around the amide or urea functionalities of organo- and hydrogelators. Irradiation with UV-light cleaved the photo-labile macrocyclic components from the [2]rotaxanes, resulting in the free gelators being released into solution and, thereafter, forming gels. When the rate of gelation was sufficiently rapid, selective gelation of specific regions of the solution-and, indeed, photo-patterning of the solution-was possible. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. A Photo-Favorskii Ring Contraction Reaction: The Effect of Ring Size

    PubMed Central

    Kammath, Viju Balachandran; Šolomek, Tomáš; Ngoy, Bokolombe Pitchou; Heger, Dominik; Klán, Petr; Rubina, Marina; Givens, Richard S.

    2012-01-01

    The effect of ring size on the photo-Favorskii induced ring-contraction reaction of the hydroxybenzocycloalkanonyl acetate and mesylate esters (7a–d, 8a–c) has provided new insight into the mechanism of the rearrangement. By monotonically decreasing the ring size in these cyclic derivatives, the increasing ring strain imposed on the formation of the elusive bicyclic spirocyclopropanone 20 results in a divergence away from rearrangement and toward solvolysis. Cycloalkanones of seven or eight carbons undergo a highly efficient photo-Favorskii rearrangement with ring contraction paralleling the photochemistry of p-hydroxyphenacyl esters. In contrast, the five-carbon ring does not rearrange but is diverted to the photosolvolysis channel avoiding the increased strain energy that would accompany the formation of the spirobicyclic ketone, the “Favorskii intermediate 20”. The six-carbon analogue demonstrates the bifurcation in reaction channels, yielding a solvent-sensitive mixture of both. Employing a combination of time-resolved absorption measurements, quantum yield determinations, isotopic labeling, and solvent variation studies coupled with theoretical treatment, a more comprehensive mechanistic description of the rearrangement has emerged. PMID:22686289

  4. Photo-switchable membrane and method

    DOEpatents

    Marshall, Kenneth L; Glowacki, Eric

    2013-05-07

    Switchable gas permeation membranes in which a photo-switchable low-molecular-weight liquid crystalline (LC) material acts as the active element, and a method of making such membranes. Different LC eutectic mixtures were doped with mesogenic azo dyes and infused into track-etched porous membranes with regular cylindrical pores. Photo-induced isothermal phase changes in the imbibed mesogenic material afforded large, reversible changes in the permeability of the photo-switchable membrane to nitrogen. For example, membranes imbibed with a photo-switchable cyanobiphenyl LC material demonstrated low permeability in the nematic state, while the photo-generated isotropic state demonstrated a 16.times.-greater sorption coefficient. Both states obey a high linear sorption behavior in accordance with Henry's Law. In contrast, membranes imbibed with a photo-switchable phenyl benzoate LC material showed the opposite permeability behavior to the biphenyl-imbibed membrane, along with nonlinear sorption behavior.

  5. Perfect absorption in nanotextured thin films via Anderson-localized photon modes

    NASA Astrophysics Data System (ADS)

    Aeschlimann, Martin; Brixner, Tobias; Differt, Dominik; Heinzmann, Ulrich; Hensen, Matthias; Kramer, Christian; Lükermann, Florian; Melchior, Pascal; Pfeiffer, Walter; Piecuch, Martin; Schneider, Christian; Stiebig, Helmut; Strüber, Christian; Thielen, Philip

    2015-10-01

    The enhancement of light absorption in absorber layers is crucial in a number of applications, including photovoltaics and thermoelectrics. The efficient use of natural resources and physical constraints such as limited charge extraction in photovoltaic devices require thin but efficient absorbers. Among the many different strategies used, light diffraction and light localization at randomly nanotextured interfaces have been proposed to improve absorption. Although already exploited in commercial devices, the enhancement mechanism for devices with nanotextured interfaces is still subject to debate. Using coherent two-dimensional nanoscopy and coherent light scattering, we demonstrate the existence of localized photonic states in nanotextured amorphous silicon layers as used in commercial thin-film solar cells. Resonant absorption in these states accounts for the enhanced absorption in the long-wavelength cutoff region. Our observations establish that Anderson localization—that is, strong localization—is a highly efficient resonant absorption enhancement mechanism offering interesting opportunities for the design of efficient future absorber layers.

  6. Acoustic enhancement for photo detecting devices

    DOEpatents

    Thundat, Thomas G; Senesac, Lawrence R; Van Neste, Charles W

    2013-02-19

    Provided are improvements to photo detecting devices and methods for enhancing the sensitivity of photo detecting devices. A photo detecting device generates an electronic signal in response to a received light pulse. An electro-mechanical acoustic resonator, electrically coupled to the photo detecting device, damps the electronic signal and increases the signal noise ratio (SNR) of the electronic signal. Increased photo detector standoff distances and sensitivities will result.

  7. Spacecraft Thermal Control Coatings References

    NASA Technical Reports Server (NTRS)

    Kauder, Lonny

    2005-01-01

    The successful thermal design of spacecraft depends in part on a knowledge of the solar absorption and hemispherical emittance of the thermal control coatings used in and on the spacecraft. Goddard Space Flight Center has had since its beginning a group whose mission has been to provide thermal/optical properties data of thermal control coatings to thermal engineers. This handbook represents a summary of the data and knowledge accumulated over many years at GSFC.

  8. Diode Laser Pumped Alkali Vapor Lasers with Exciplex-Assisted Absorption

    DTIC Science & Technology

    2013-05-14

    transfer agent that established the population inversion. The excitation source used in these initial studies was a pulsed optical parametric oscillator ...parametric oscillator . The lasers operated at 703.2 (Ne*), 912.5 (Ar*), 893.1 (Kr*) and 980.2 run (Xe*). Peak powers as high as 27kW/cm2 were observed...Larissa Glebova and Leonid B. Glebov. Ultra-low absorption and laser-induced heating of volume Bragg combiners recorded in photo-thermo- refractive

  9. Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.

    2015-12-14

    Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintainingmore » high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.« less

  10. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Central Library NOAA Privacy Policy | NOAA Disclaimer Last Updated: November 10, 2017

  11. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Library NOAA Privacy Policy | NOAA Disclaimer Last Updated: November 10, 2017

  12. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image Commerce, National Oceanic & Atmospheric Adminstration (NOAA), NOAA Central Library NOAA Privacy Policy

  13. A general strategy for developing cell-permeable photo-modulatable organic fluorescent probes for live-cell super-resolution imaging.

    PubMed

    Pan, Deng; Hu, Zhe; Qiu, Fengwu; Huang, Zhen-Li; Ma, Yilong; Wang, Yina; Qin, Lingsong; Zhang, Zhihong; Zeng, Shaoqun; Zhang, Yu-Hui

    2014-11-20

    Single-molecule localization microscopy (SMLM) achieves super-resolution imaging beyond the diffraction limit but critically relies on the use of photo-modulatable fluorescent probes. Here we report a general strategy for constructing cell-permeable photo-modulatable organic fluorescent probes for live-cell SMLM by exploiting the remarkable cytosolic delivery ability of a cell-penetrating peptide (rR)3R2. We develop photo-modulatable organic fluorescent probes consisting of a (rR)3R2 peptide coupled to a cell-impermeable organic fluorophore and a recognition unit. Our results indicate that these organic probes are not only cell permeable but can also specifically and directly label endogenous targeted proteins. Using the probes, we obtain super-resolution images of lysosomes and endogenous F-actin under physiological conditions. We resolve the dynamics of F-actin with 10 s temporal resolution in live cells and discern fine F-actin structures with diameters of ~80 nm. These results open up new avenues in the design of fluorescent probes for live-cell super-resolution imaging.

  14. Photos above SM Hatch

    NASA Image and Video Library

    2013-01-02

    View of Yuri Alexievich Gagarin (first space traveler) photo and other photos,above Service Module (SM) hatch. The blue and white rosette on the left with the writing пора в космос is the symbol and name of the Russian television program for children that covers cosmonautic and International Space Station (ISS) topics. Photo was taken during Expedition 34.

  15. Predictors of photo naming: Dutch norms for 327 photos.

    PubMed

    Shao, Zeshu; Stiegert, Julia

    2016-06-01

    In the present study, we report naming latencies and norms for 327 photos of objects in Dutch. We provide norms for eight psycholinguistic variables: age of acquisition, familiarity, imageability, image agreement, objective and subjective visual complexity, word frequency, word length in syllables and letters, and name agreement. Furthermore, multiple regression analyses revealed that the significant predictors of photo-naming latencies were name agreement, word frequency, imageability, and image agreement. The naming latencies, norms, and stimuli are provided as supplemental materials.

  16. Effect of Aluminum on Characterization of ZnTe/n-Si Heterojunction Photo detector

    NASA Astrophysics Data System (ADS)

    Maki, Samir A.; Hassun, Hanan K.

    2018-05-01

    Aluminum doped zinc telluride ZnTenSi thin films of (400nm) thickness with (005 01 015 and 02) wt % were deposited on the glass substrate and nSi wafer to fabricate ZnTenSi heterojunction Photodetector by using thermal vacuum evaporation technique Structural optical electrical and photovoltaic properties are investigated for the samples XRD analysis shows that all the deposited ZnTenSi films show polycrystalline structure with cubic phases and highest sharp peak corresponding to (111) planes and from AFM images shows the surface roughness increase with increase Al percentage ratio The optical absorption measurement of the films was find from transmittance ranges in the variety of wavelength (400 1000) nm and the optical energy band gap decrease from 224 eV to 186 eV dependent upon the Aluminum ratio in the films moreover our studies contain the calculation of the electrical properties of hetero junction were obtained via IV (dark and light condition) and C V measurement The photoelectric properties indicated rise illumination current of heterojunctions through increasing both of incident lighting intensity and Aluminum dopant The values of specific detectivity and quantum efficiency are calculated for all samples also the best spectral response occurs when Al doping ratio 02% The high photo sensitivity and comparatively fast response haste are attributable to in height crystal quality of the [ZnTe ] thin films.

  17. Anisotropy of band gap absorption in TlGaSe2 semiconductor by ferroelectric phase transformation

    NASA Astrophysics Data System (ADS)

    Gulbinas, Karolis; Grivickas, Vytautas; Gavryushin, Vladimir

    2014-12-01

    The depth-resolved free-carrier absorption and the photo-acoustic response are used to examine the band-gap absorption in 2D-TlGaSe2 layered semiconductor after its transformation into the ferroelectric F-phase below 107 K. The absorption exhibits unusual behavior with a biaxial character in respect to the light polarization on the layer plane. A spectral analysis shows that the anisotropy is associated to the lowest Γ-direct optical transition. The Γ-absorption and the localized exciton at 2.11 eV are dipole-prohibited or partially allowed in two nearly perpendicular polarization directions. The shift of anisotropy axis in respect to crystallographic a- and b-directions demonstrates the non-equivalent zigzag rearrangement of the interlayer connecting Tl+ ions, which is responsible for occurrence of the F-phase.

  18. Fabrication and performance of efficient thin circular polarization gratings with Bragg properties using bulk photo-alignment of a liquid crystalline polymer

    NASA Astrophysics Data System (ADS)

    Sakhno, Oksana; Gritsai, Yuri; Sahm, Hagen; Stumpe, Joachim

    2018-03-01

    Thin circular polarization gratings, characterized by high diffraction efficiency and large, up to 42°, diffraction angles were created by polarization holography for the first time. The high efficiency of the gratings is the result of the specific properties of a photo-crosslinkable liquid crystalline polymer and a two-step photochemical/thermal processing procedure. A diffraction efficiency of up to 98% at 532 nm has been achieved for gratings with periods of 700 nm. In contrast to polarization gratings with larger periods these gratings exhibit Bragg properties. So one beam is either transmitted or diffracted depending on the direction of the circular polarization of the incident light, whereas the maximal diffraction efficiency is achieved only at the proper incident angle. The fabrication procedure consists of holographic exposure of the film at room temperature which provides the photo-selective cycloaddition of cinnamic ester groups. Upon subsequent thermal annealing above T g bulk photo-alignment of the LC polymer film occurs enhancing the optical anisotropy within the grating. The holographic patterning provides high spatial resolution, the arbitrary orientation of the LC director as well as high optical quality, thermal and chemical stability of the final gratings. Highly efficient symmetric and slanted circular polarization gratings were fabricated with the proposed technique.

  19. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image ' Waterspouts" by Joseph H. Golden, NOAA Technical Memorandum ERL NSSL-70, 1974. Library Call Number

  20. NOAA Photo Library

    Science.gov Websites

    cells. TIROS II was the first meteorological satellite to have infra-red sensors as well as television - spac0116 Making adjustments to TIROS II satellite prior to launch. Small square objects are 9,260 solar Collection Photo Date: 1960, November Category: Space/Satellite/Vehicle/ * High Resolution Photo Available

  1. The effect of silver on the optical, spectral-luminescent, and crystallization properties of bromide photo-thermo-refractive glasses

    NASA Astrophysics Data System (ADS)

    Oreshkina, K. V.; Dubrovin, V. D.; Ignat'ev, A. I.; Nikonorov, N. V.

    2017-10-01

    The effect of silver on the optical, spectral-luminescent, and crystallization properties of bromide photo-thermo-refractive glasses is studied. Multicomponent photosensitive glasses of the Na2O-ZnO-Al2O3-SiO2 system with photosensitizing agents (cerium, antimony, silver) and halogenides (fluorine and bromine) are synthesized. Ultraviolet irradiation and thermal treatment below the glass-transition temperature of the glasses cause the formation of silver molecular clusters, which exhibit luminescence in the visible and infrared regions. UV irradiation and thermal treatment of glasses above the glass-transition temperature lead to the growth of silver nanoparticles with plasmon resonance peak in the region of 420 nm. Further thermal treatment of glasses above the glass-transition temperature shifts the plasmon-resonance maximum by 70 nm to longer wavelengths, which is related to the growth of a crystalline shell consisting of mixed silver and sodium bromides on nanoparticles. This formation of a crystalline phase on colloidal centers results in a local increase in the refractive index of the irradiated region by +Δ n 900 ppm compared to the nonirradiated region. Photo-thermo-refractive glasses with increased silver concentration are promising photosensitive materials for creating holographic optical elements and devices for line narrowing and stabilizing filters, spectral beam combiners, and filters for increasing the spectral brightness of laser diodes. A positive change in the refractive index of Photo-thermo-refractive glasses provides the possibility of recording in them 3D waveguide and integrated-optical structures.

  2. Absorption of Bile Pigments by the Gall Bladder*

    PubMed Central

    Ostrow, J. Donald

    1967-01-01

    A technique is described for preparation in the guinea pig of an in situ, isolated, vascularized gall bladder that exhibits normal absorptive functions. Absorption of labeled bile pigments from the gall bladder was determined by the subsequent excretion of radioactivity in hepatic bile. Over a wide range of concentrations, unconjugated bilirubin-14C was well absorbed, whereas transfer of conjugated bilirubin proceeded slowly. Mesobilirubinogen-3H was absorbed poorly from whole bile, but was absorbed as rapidly as unconjugated bilirubin from a solution of pure conjugated bile salt. Bilirubin absorption was not impaired by iodoacetamide, 1.5 mM, or dinitrophenol, 1.0 mM, even though water transport was affected. This indicated that absorption of bilirubin was not dependent upon water transport, nor upon energy-dependent processes. The linear relationship between absorption and concentration of pigment at low concentrations in bile salt solutions suggested that pigment was transferred by passive diffusion. At higher pigment concentrations or in whole bile, this simple relationship was modified by interactions of pigment with bile salts and other constituents of bile. These interactions did not necessarily involve binding of bilirubin in micelles. The slow absorption of the more polar conjugates and photo-oxidative derivatives of bilirubin suggested that bilirubin was absorbed principally by nonionic, and partially, by ionic diffusion. Concentrations of pure conjugated bile salts above 3.5 mM were found to be injurious to the gall bladder mucosa. This mucosal injury did not affect the kinetics of bilirubin absorption. During in vitro incubation of bile at 37°C, decay of bilirubin and hydrolysis of the conjugate proceeded as first-order reactions. The effects of these processes on the kinetics of bilirubin absorption, and their possible role in the formation of “white bile” and in the demonstrated appearance of unconjugated bilirubin in hepatic bile, are discussed

  3. Spatial and temporal control of thermal waves by using DMDs for interference based crack detection

    NASA Astrophysics Data System (ADS)

    Thiel, Erik; Kreutzbruck, Marc; Ziegler, Mathias

    2016-02-01

    Active Thermography is a well-established non-destructive testing method and used to detect cracks, voids or material inhomogeneities. It is based on applying thermal energy to a samples' surface whereas inner defects alter the nonstationary heat flow. Conventional excitation of a sample is hereby done spatially, either planar (e.g. using a lamp) or local (e.g. using a focused laser) and temporally, either pulsed or periodical. In this work we combine a high power laser with a Digital Micromirror Device (DMD) allowing us to merge all degrees of freedom to a spatially and temporally controlled heat source. This enables us to exploit the possibilities of coherent thermal wave shaping. Exciting periodically while controlling at the same time phase and amplitude of the illumination source induces - via absorption at the sample's surface - a defined thermal wave propagation through a sample. That means thermal waves can be controlled almost like acoustical or optical waves. However, in contrast to optical or acoustical waves, thermal waves are highly damped due to the diffusive character of the thermal heat flow and therefore limited in penetration depth in relation to the achievable resolution. Nevertheless, the coherence length of thermal waves can be chosen in the mmrange for modulation frequencies below 10 Hz which is perfectly met by DMD technology. This approach gives us the opportunity to transfer known technologies from wave shaping techniques to thermography methods. We will present experiments on spatial and temporal wave shaping, demonstrating interference based crack detection.

  4. Hydrolysis Batteries: Generating Electrical Energy during Hydrogen Absorption.

    PubMed

    Xiao, Rui; Chen, Jun; Fu, Kai; Zheng, Xinyao; Wang, Teng; Zheng, Jie; Li, Xingguo

    2018-02-19

    The hydrolysis reaction of aluminum can be decoupled into a battery by pairing an Al foil with a Pd-capped yttrium dihydride (YH 2 -Pd) electrode. This hydrolysis battery generates a voltage around 0.45 V and leads to hydrogen absorption into the YH 2 layer. This represents a new hydrogen absorption mechanism featuring electrical energy generation during hydrogen absorption. The hydrolysis battery converts 8-15 % of the thermal energy of the hydrolysis reaction into usable electrical energy, leading to much higher energy efficiency compared to that of direct hydrolysis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Infrared absorption nano-spectroscopy using sample photoexpansion induced by tunable quantum cascade lasers.

    PubMed

    Lu, Feng; Belkin, Mikhail A

    2011-10-10

    We report a simple technique that allows obtaining mid-infrared absorption spectra with nanoscale spatial resolution under low-power illumination from tunable quantum cascade lasers. Light absorption is detected by measuring associated sample thermal expansion with an atomic force microscope. To detect minute thermal expansion we tune the repetition frequency of laser pulses in resonance with the mechanical frequency of the atomic force microscope cantilever. Spatial resolution of better than 50 nm is experimentally demonstrated.

  6. Terahertz sensing of highly absorptive water-methanol mixtures with multiple resonances in metamaterials.

    PubMed

    Chen, Min; Singh, Leena; Xu, Ningning; Singh, Ranjan; Zhang, Weili; Xie, Lijuan

    2017-06-26

    Terahertz sensing of highly absorptive aqueous solutions remains challenging due to strong absorption of water in the terahertz regime. Here, we experimentally demonstrate a cost-effective metamaterial-based sensor integrated with terahertz time-domain spectroscopy for highly absorptive water-methanol mixture sensing. This metamaterial has simple asymmetric wire structures that support multiple resonances including a fundamental Fano resonance and higher order dipolar resonance in the terahertz regime. Both the resonance modes have strong intensity in the transmission spectra which we exploit for detection of the highly absorptive water-methanol mixtures. The experimentally characterized sensitivities of the Fano and dipole resonances for the water-methanol mixtures are found to be 160 and 305 GHz/RIU, respectively. This method provides a robust route for metamaterial-assisted terahertz sensing of highly absorptive chemical and biochemical materials with multiple resonances and high accuracy.

  7. High sensitivity background absorption measurements in semiconductors

    NASA Astrophysics Data System (ADS)

    Giannini, Nathan; Silva, Junior R.; Wang, Chengao; Albrecht, Alexander R.; Melgaard, Seth D.; Sheik-Bahae, Mansoor

    2015-03-01

    Laser cooling in InGaP|GaAs double heterostructures (DHS) has been a sought after goal. Even though very high external quantum efficiency (EQE) has been achieved, background absorption has remained a bottleneck in achieving net cooling. The purpose of this study is to gain more insight into the source of the background absorption for InGaP|GaAs DHS as well as GaAs|AlGaAs DBRs by employing an excite-probe thermal Z-scan measurement.

  8. Magneto-photo-acoustic imaging

    PubMed Central

    Qu, Min; Mallidi, Srivalleesha; Mehrmohammadi, Mohammad; Truby, Ryan; Homan, Kimberly; Joshi, Pratixa; Chen, Yun-Sheng; Sokolov, Konstantin; Emelianov, Stanislav

    2011-01-01

    Magneto-photo-acoustic imaging, a technique based on the synergy of magneto-motive ultrasound, photoacoustic and ultrasound imaging, is introduced. Hybrid nanoconstructs, liposomes encapsulating gold nanorods and iron oxide nanoparticles, were used as a dual-contrast agent for magneto-photo-acoustic imaging. Tissue-mimicking phantom and macrophage cells embedded in ex vivo porcine tissue were used to demonstrate that magneto-photo-acoustic imaging is capable of visualizing the location of cells or tissues labeled with dual-contrast nanoparticles with sufficient contrast, excellent contrast resolution and high spatial resolution in the context of the anatomical structure of the surrounding tissues. Therefore, magneto-photo-acoustic imaging is capable of identifying the nanoparticle-labeled pathological regions from the normal tissue, providing a promising platform to noninvasively diagnose and characterize pathologies. PMID:21339883

  9. Mechanisms of Photo-Induced Deformations of Liquid Crystal Elastomers

    NASA Astrophysics Data System (ADS)

    Dawson, Nathan; Kuzyk, Mark; Neal, Jeremy; Luchette, Paul; Palffy-Muhoray, Peter

    2010-03-01

    Over a century ago, Alexander Graham Bell invented the photophone, which he used to transmit mechanical information on a beam of light. We report on the use of an active Fabry-Perot interferometer to encode and detect mechanical information using the photomechanical effect of a liquid crystal elastomer (LCE) that is placed at a critical point between the reflectors. These are the first steps in the creation of ultra smart materials which require a large photomechanical response. Thus, understanding the underlying mechanisms is critical. Only limited studies of the mechanisms of the photomechanical effect, such as photo-isomerization, photo-reorientation and thermal effects have been studied in azo-dye-doped LCEs and in azo-dye-doped polymer fibers have been reported. The focus of our present work is to use the Fabry-Perot transducer geometry to study the underlying mechanisms and to determine the relevant material parameters that are used to develop theoretical models of the response. We use various intensity-modulated optical wave forms to determine the frequency response of the material, which are used to predict the material response.

  10. Photo-physical and interactional behavior of two members of group B vitamins in different solvent media

    NASA Astrophysics Data System (ADS)

    Zakerhamidi, M. S.; Zare Haghighi, L.; Seyed Ahmadian, S. M.

    2017-09-01

    In this paper, absorption and fluorescence spectra of vitamin B12 (cyanocobalamin) and vitamin B6 (pyridoxine) were recorded in solvents with different polarity, at room temperature. These vitamins' photo-physical behavior depends strongly on the solvent's nature along with different attached groups in their structures. In order to investigate the solvent-solute interactions and environmental effect on spectral variations, linear solvation energy relationships concept, suggested by Kamlet and Taft was used. Solvatochromic method was also used for measuring the ground and excited state dipole moments of these vitamins. According to our experimental results, dipole moment of these groups of vitamins in excited state is larger than ground state. Furthermore, obtained photo-physical and interactional properties of used vitamins can give important information on how this group of vitamins behaves in biological systems.

  11. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image -Welt...." by Erasmus Francisci, 1680. Library Call Number QC859 .F72 1680. Image ID: wea02217

  12. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image ] unserer Nider-Welt...." by Erasmus Francisci, 1680. Library Call Number QC859 .F72 1680. Image ID

  13. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image the late Dr. Benjamin Franklin ....", 1806. Volume II, p. 26. Library Call Number PS745 .A2 1806

  14. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image - spac0020 ESSA I, a TIROS cartwheel satellite launched on February 3, 1966. Image ID: spac0020, NOAA In

  15. Thermal Analysis of Thermal Protection System of Test Launch Vehicle

    NASA Astrophysics Data System (ADS)

    Kim, Jongmin

    2017-10-01

    In this paper, a thermal analysis of the thermal protection system (TPS) of test launch vehicle (TLV) is explained. TLV is heated during the flight due to engine exhaust plume gas by thermal radiation and a TPS is needed to protect the vehicle from the heating. The thermal analysis of the TPS is conducted to predict the heat flux from plume gas and temperature of the TPS during the flight. To simplify the thermal analysis, plume gas radiation and radiative properties are assumed to be surface radiation and constants, respectively. Thermal conductivity, emissivity and absorptivity of the TPS material are measured. Proper plume conditions are determined from the preliminary analysis and then the heat flux and temperature of the TPS are calculated.

  16. Short Pulse Laser Absorption and Energy Partition at Relativistic Laser Intensities

    NASA Astrophysics Data System (ADS)

    Ping, Yuan

    2005-10-01

    We present the first absorption measurements at laser intensity between 10^17 to 10^20 W/cm^2 using an intergrating sphere and a suite of diagnostics that measures scale length, hot electrons and laser harmonics. A much-enhanced absorption in the regime of relativestic electron heating was observed. Furthermore, we present measurements on the partitioning of absorbed laser energy into thermal and non-thermal electrons when illuminating solid targets from 10^17 to 10^19 W/cm^2. This was measured using a sub-picosecond x-ray streak camera interfaced to a dual crystal von H'amos crystal spectrograph, a spherical crystal x-ray imaging spectrometer, an electron spectrometer and optical spectrometer. Our data suggests an intensity dependent energy-coupling transition with greater energy portion into non-thermal electrons that rapidly transition to thermal electrons. The details of these experimental results and modeling simulations will be presented.

  17. Absorption fluids data survey

    NASA Astrophysics Data System (ADS)

    Macriss, R. A.; Zawacki, T. S.

    Development of improved data for the thermodynamic, transport and physical properties of absorption fluids were studied. A specific objective of this phase of the study is to compile, catalog and coarse screen the available US data of known absorption fluid systems and publish it as a first edition document to be distributed to manufacturers, researchers and others active in absorption heat pump activities. The methodology and findings of the compilation, cataloguing and coarse screening of the available US data on absorption fluid properties and presents current status and future work on this project are summarized. Both in house file and literature searches were undertaken to obtain available US publications with pertinent physical, thermodynamic and transport properties data for absorption fluids. Cross checks of literature searches were also made, using available published bibliographies and literature review articles, to eliminate secondary sources for the data and include only original sources and manuscripts. The properties of these fluids relate to the liquid and/or vapor state, as encountered in normal operation of absorption equipment employing such fluids, and to the crystallization boundary of the liquid phase, where applicable. The actual data were systematically classified according to the type of fluid and property, as well as temperature, pressure and concentration ranges over which data were available. Data were sought for 14 different properties: Vapor-Liquid Equilibria, Crystallization Temperature, Corrosion Characteristics, Heat of Mixing, Liquid-Phase-Densities, Vapor-Liquid-Phase Enthalpies, Specific Heat, Stability, Viscosity, Mass Transfer Rate, Heat Transfer Rate, Thermal Conductivity, Flammability, and Toxicity.

  18. Geochemistry of thermal fluids in NW Honduras: New perspectives for exploitation of geothermal areas in the southern Sula graben

    NASA Astrophysics Data System (ADS)

    Capaccioni, Bruno; Franco, Tassi; Alberto, Renzulli; Orlando, Vaselli; Marco, Menichetti; Salvatore, Inguaggiato

    2014-06-01

    geothermal sites of the southern Sula graben (Laguna de Agua Caliente and El Olivar) are covered by the Oligocene-Miocene volcano-sedimentary sequences of the Matagalpa formation, possibly acting as efficient impermeable cap rocks. These results significantly differ from those reported by previous studies and emphasize that the southern Sula graben, in particular the El Olivar area, can represent among the investigated thermal springs, the most promising site for the exploitation of a high-enthalpy geothermal field.

  19. Photothermal cancer therapy using intravenously injected near-infrared-absorbing nanoparticles

    NASA Astrophysics Data System (ADS)

    O'Neal, D. P.; Hirsch, Leon R.; Halas, Naomi J.; Payne, J. D.; West, Jennifer L.

    2005-04-01

    This report focuses on the treatment parameters leading to successful nanoshell-assisted photo-thermal therapy (NAPT). NAPT takes advantage of the strong near infrared (NIR) absorption of gold-silica nanoshells, a new class of nanoparticles with tunable optical absorptivities that are capable of passive extravasation from the abnormal tumor vasculature due to their nanoscale size. Under controlled conditions nanoshells accumulate in tumors with superior efficiency compared to surrounding tissues. For this treatment: (1) tumors were inoculated in immune-competent mice by subcutaneous injection, (2) polyethylene glycol coated nanoshells (~150 nm diameter) with peak optical absorption in the NIR were intravenously injected and allowed to circulate for 6 - 48 hours, and (3) tumors were then extracorporeally illuminated with a collimated diode laser (808 nm, 2-6 W/cm2, 2-4 min). Nanoshell accumulations were quantitatively assessed in tumors and surrounding tissues using neutron activation analysis for gold. In order to assess temperature elevation, laser therapies were monitored in real-time using a mid-infrared thermal sensor. NAPT resulted in complete tumor regression in >90% of the subjects. This simple, non-invasive procedure shows great promise as a technique for selective photo-thermal tumor treatment.

  20. 'Squeezing' near-field thermal emission for ultra-efficient high-power thermophotovoltaic conversion.

    PubMed

    Karalis, Aristeidis; Joannopoulos, J D

    2016-07-01

    We numerically demonstrate near-field planar ThermoPhotoVoltaic systems with very high efficiency and output power, at large vacuum gaps. Example performances include: at 1200 °K emitter temperature, output power density 2 W/cm(2) with ~47% efficiency at 300 nm vacuum gap; at 2100 °K, 24 W/cm(2) with ~57% efficiency at 200 nm gap; and, at 3000 °K, 115 W/cm(2) with ~61% efficiency at 140 nm gap. Key to this striking performance is a novel photonic design forcing the emitter and cell single modes to cros resonantly couple and impedance-match just above the semiconductor bandgap, creating there a 'squeezed' narrowband near-field emission spectrum. Specifically, we employ surface-plasmon-polariton thermal emitters and silver-backed semiconductor-thin-film photovoltaic cells. The emitter planar plasmonic nature allows for high-power and stable high-temperature operation. Our simulations include modeling of free-carrier absorption in both cell electrodes and temperature dependence of the emitter properties. At high temperatures, the efficiency enhancement via resonant mode cross-coupling and matching can be extended to even higher power, by appropriately patterning the silver back electrode to enforce also an absorber effective surface-plasmon-polariton mode. Our proposed designs can therefore lead the way for mass-producible and low-cost ThermoPhotoVoltaic micro-generators and solar cells.

  1. Principles of thermal remote sensing

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The remote sensing of temperature is performed by sensing radiation emitted from solids, liquids, and gases in the thermal infrared region of the spectrum, in which thermal emission is dominant over reflected solar energy. For Earth resources applications, thermal sensing of solids and liquids is performed in two ""windows'' of the atmosphere where atmospheric absorption and emission are at a minimum. Temperature measurement, intrinsic thermal properties, factors in interpreting thermal data, the use of thermal inertia, and the measurements obtained by the heat capacity mapping radiometer are discussed.

  2. Design of a thermal waist-pad

    NASA Astrophysics Data System (ADS)

    Kursun Bahadir, S.; Sahin, U. K.; Acikgoz Tufan, H.

    2017-10-01

    The objective of the current study is designing a thermal waist-pad for people who have backaches with a sandwich-like multi-layered structure. Two model is developed; one is three-layered and second is five-layered with waterproof woven outer layer fabric, Thermolite® knitted fabric (for five-layered structures), wool knitted, polyester nonwoven fabric, polypropylene nonwoven fabric and viscose nonwoven fabric for mid-layer. 10 different structures are designed and produced. All samples are tested for thermal comfort properties of waist-pad. Multi-layer structures were tested, and according to their thermal performance and thermal comfort criteria, all results are evaluated for identifying the best product. These three factors are examined by analysis of thermal conductivity, thermal resistance, thermal absorptivity, relative water vapour/air permeability, water absorption. Highest thermal resistance test result, 150,42 mK/Wm2, is achieved in five-layered sandwich structure with waterproof fabric, Thermolite® fabric, wool based knitted fabric, Thermolite® fabric and waterproof fabric, respectively. Thermal conductivity result of this structure is 46,2 mW/mK, which is one of the lowest results among the alternative structures. Structures with Thermolite® fabric show higher thermal comfort when compared to others.

  3. Optical design of nanowire absorbers for wavelength selective photodetectors

    PubMed Central

    Mokkapati, S.; Saxena, D.; Tan, H. H.; Jagadish, C.

    2015-01-01

    We propose the optical design for the absorptive element of photodetectors to achieve wavelength selective photo response based on resonant guided modes supported in semiconductor nanowires. We show that the waveguiding properties of nanowires result in very high absorption efficiency that can be exploited to reduce the volume of active semiconductor compared to planar photodetectors, without compromising the photocurrent. We present a design based on a group of nanowires with varying diameter for multi-color photodetectors with small footprint. We discuss the effect of a dielectric shell around the nanowires on the absorption efficiency and present a simple approach to optimize the nanowire diameter-dielectric shell thickness for maximizing the absorption efficiency. PMID:26469227

  4. Josephson Thermal Memory

    NASA Astrophysics Data System (ADS)

    Guarcello, Claudio; Solinas, Paolo; Braggio, Alessandro; Di Ventra, Massimiliano; Giazotto, Francesco

    2018-01-01

    We propose a superconducting thermal memory device that exploits the thermal hysteresis in a flux-controlled temperature-biased superconducting quantum-interference device (SQUID). This system reveals a flux-controllable temperature bistability, which can be used to define two well-distinguishable thermal logic states. We discuss a suitable writing-reading procedure for these memory states. The time of the memory writing operation is expected to be on the order of approximately 0.2 ns for a Nb-based SQUID in thermal contact with a phonon bath at 4.2 K. We suggest a noninvasive readout scheme for the memory states based on the measurement of the effective resonance frequency of a tank circuit inductively coupled to the SQUID. The proposed device paves the way for a practical implementation of thermal logic and computation. The advantage of this proposal is that it represents also an example of harvesting thermal energy in superconducting circuits.

  5. Narrowband thermal radiation from closed-end microcavities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kohiyama, Asaka; Shimizu, Makoto; Iguchi, Fumitada

    2015-10-07

    High spectral selectivity of thermal radiation is important for achieving high-efficiency energy systems. In this study, intense, narrowband, and low directional absorption/radiation were observed in closed-end microcavity which is a conventional open-end microcavity covered by a semi-transparent thin metal film. The quality factor (Q factor) of optical absorption band strongly depended on the film electrical conductivity. Asymmetric and narrow absorption band with a Q factor of 25 at 1.28 μm was obtained for a 6-nm-thick Au film. Numerical simulations suggest that the formation of a fixed-end mode at the cavity aperture contributes to the narrowband optical absorption. The closed-end microcavity filledmore » with SiO{sub 2} exhibits intense and isotropic thermal radiation over a wide solid angle according to numerical simulation. The narrow and asymmetric absorption spectrum was experimentally confirmed in a model of closed-end microcavity.« less

  6. Characterization of the physico-chemical properties of polymeric materials for aerospace flight. [differential thermal and atomic absorption spectroscopic analysis of nickel cadmium batteries

    NASA Technical Reports Server (NTRS)

    Rock, M.

    1981-01-01

    Electrodes and electrolytes of nickel cadmium sealed batteries were analyzed. Different thermal analysis of negative and positive battery electrodes was conducted and the temperature ranges of occurrence of endotherms indicating decomposition of cadmium hydroxide and nickel hydroxide are identified. Atomic absorption spectroscopy was used to analyze electrodes and electrolytes for traces of nickel, cadmium, cobalt, and potassium. Calibration curves and data are given for each sample analyzed. Instrumentation and analytical procedures used for each method are described.

  7. NOAA Photo Library

    Science.gov Websites

    - nssl0057 Early stage of tornado formation. Photo #1 of a series of classic photographs of this tornado Available Publication of the U.S. Department of Commerce, National Oceanic & Atmospheric Adminstration NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes

  8. Ultrahigh photo-responsivity and detectivity in multilayer InSe nanosheets phototransistors with broadband response

    DOE PAGES

    Feng, Wei; Wu, Jing-Bin; Li, Xiaoli; ...

    2015-05-20

    In this paper, we demonstrate the strategies and principles for the performance improvement of layered semiconductor based photodetectors using multilayer indium selenide (InSe) as the model material. It is discovered that multiple reflection interference at the interfaces in the phototransistor device leads to a thickness-dependent photo-response, which provides a guideline to improve the performance of layered semiconductor based phototransistors. The responsivity and detectivity of InSe nanosheet phototransistor can be adjustable using applied gate voltage. Our InSe nanosheet phototransistor exhibits ultrahigh responsivity and detectivity. An ultrahigh external photo-responsivity of ~10 4 A W -1 can be achieved from broad spectra rangingmore » from UV to near infrared wavelength using our InSe nanosheet photodetectors. The detectivity of multilayer InSe devices is ~10 12 to 10 13 Jones, which surpasses that of the currently exploited InGaAs photodetectors (10 11 to 10 12 Jones). Finally, this research shows that multilayer InSe nanosheets are promising materials for high performance photodetectors.« less

  9. Nanoplasmon-enabled macroscopic thermal management

    PubMed Central

    Jonsson, Gustav Edman; Miljkovic, Vladimir; Dmitriev, Alexandre

    2014-01-01

    In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial. PMID:24870613

  10. Heat exchange studies on coconut oil cells as thermal energy storage for room thermal conditioning

    NASA Astrophysics Data System (ADS)

    Sutjahja, I. M.; Putri, Widya A.; Fahmi, Z.; Wonorahardjo, S.; Kurnia, D.

    2017-07-01

    As reported by many thermal environment experts, room air conditioning might be controlled by thermal mass system. In this paper we discuss the performance of coconut oil cells as room thermal energy storage. The heat exchange mechanism of coconut oil (CO) which is one of potential organic Phase Change Material (PCM) is studied based on the results of temperature measurements in the perimeter and core parts of cells. We found that the heat exchange performance, i.e. heat absorption and heat release processes of CO cells are dominated by heat conduction in the sensible solid from the higher temperature perimeter part to the lower temperature core part and heat convection during the solid-liquid phase transition and sensible liquid phase. The capability of heat absorption as measured by the reduction of air temperature is not influenced by CO cell size. Besides that, the application of CO as the thermal mass has to be accompanied by air circulation to get the cool sensation of the room’s occupants.

  11. Efficient photo-catalytic degradation of malachite green using nickel tungstate material as photo-catalyst.

    PubMed

    Helaïli, N; Boudjamaa, A; Kebir, M; Bachari, K

    2017-03-01

    The present study focused on the evaluation of photo-catalytic and photo-electrochemical properties of the photo-catalyst based on nickel tungstate material prepared by a nitrate method through the degradation of malachite green (MG) dye's. The effect of catalyst loading and dye concentration was examined. Physico-chemical, optical, electrical, electrochemical, and photo-electrochemical properties of the prepared material were analyzed by X-ray diffraction (XRD), fourier transform-infrared spectroscopy (FTIR), BET analysis, optical reflectance diffuse (DR), scanning electron microscopy (SEM/EDX), electrical conductivity, cyclic voltammetry (CV), current intensity, mott-shottky, and nyquist. XRD revealed the formation of monoclinic structure with a small particle size. BET surface area of the sample was around 10 m 2 /g. The results show that the degradation of MG was more than 80%, achieved after 3 h of irradiation at pH 4.6 and with a catalyst loading of 75 mg. Also, it was found that the dye photo-degradation obeyed the pseudo-first order kinetic via Langmuir Hinshelwood model.

  12. Optical absorption and radiative heat transport in olivine at high temperature

    NASA Technical Reports Server (NTRS)

    Shankland, T. J.; Nitsan, U.; Duba, A. G.

    1979-01-01

    Results are presented of measurements of the optical absorption spectra (300-8000 nm) of olivine as a function of temperature (300-1700 K) under conditions of controlled and known oxygen fugacity within the stability field of the samples. The absorption spectra are used to calculate the temperature-dependent radiative transfer coefficient of olivine and to numerically study the accuracy of the method. The present absorption measurements in olivine under oxidizing conditions known to be within the olivine stability field indicate that the effective radiative conductivity K(R) is lower than that obtained in previous studies under different experimental conditions. The lower value of K(R) makes it more likely that some of the earth's internal heat is removed by convection and less likely that thermal models involving conduction and radiation alone will satisfactorily explain thermal conditions in the earth's mantle.

  13. Enhanced photo-catalytic activity of ordered mesoporous indium oxide nanocrystals in the conversion of CO2 into methanol.

    PubMed

    Gondal, M A; Dastageer, M A; Oloore, L E; Baig, U; Rashid, S G

    2017-07-03

    Ordered mesoporous indium oxide nanocrystal (m-In 2 O 3 ) was synthesized by nanocasting technique, in which highly ordered mesoporous silca (SBA-15) was used as structural matrix. X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halanda (BJH) studies were carried out on m-In 2 O 3 and the results revealed that this material has a highly ordered mesoporous surface with reduced grain size, increased surface area and surface volume compared to the non porous indium oxide. The diffuse reluctance spectrum exhibited substantially improved light absorption efficiency in m-In 2 O 3 compared to normal indium oxide, however, no considerable change in the band gap energies of these materials was observed. When m-In 2 O 3 was used as a photo-catalyst in the photo-catalytic process of converting carbon dioxide (CO 2 ) into methanol under the pulsed laser radiation of 266-nm wavelengths, an enhanced photo-catalytic activity with the quantum efficiency of 4.5% and conversion efficiency of 46.3% were observed. It was found that the methanol production yield in this chemical process is as high as 485 µlg -1 h -1 after 150 min of irradiation, which is substantially higher than the yields reported in the literature. It is quite clear from the results that the introduction of mesoporosity in indium oxide, and the consequent enhancement of positive attributes required for a photo-catalyst, transformed photo-catalytically weak indium oxide into an effective photo-catalyst for the conversion of CO 2 into methanol.

  14. Thermally driven electrokinetic energy conversion with liquid water microjets

    DOE PAGES

    Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; ...

    2015-11-01

    One goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.

  15. Thermally driven electrokinetic energy conversion with liquid water microjets

    NASA Astrophysics Data System (ADS)

    Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; Saykally, Richard J.

    2015-11-01

    A goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.

  16. Photo-induced heat generation in non-plasmonic nanoantennas.

    PubMed

    Danesi, Stefano; Gandolfi, Marco; Carletti, Luca; Bontempi, Nicolò; De Angelis, Costantino; Banfi, Francesco; Alessandri, Ivano

    2018-05-24

    Light-to-heat conversion in non-plasmonic, high refractive index nanoantennas is a key topic for many applications, including Raman sensing, laser writing, nanofabrication and photo-thermal therapy. However, heat generation and propagation in non-plasmonic antennas is increasingly debated and contradictory results have been reported so far. Here we report a finite element analysis of the steady-state temperature distribution and heat flow in SiO2/Si core/shell systems (silicon nanoshells) irradiated with different continuous wave lasers (λ = 532, 633 and 785 nm), under real working conditions. The complex interplay among the optical properties, morphology, degree of crystallinity of the nanoshells, thickness dependence of thermal conductivity and interactions with the substrate has been elucidated. This study reveals that all of these parameters can be appropriately combined for obtaining either stable nanoshells for Raman sensing or highly efficient sources of local heating. The optimal balance between thermal stability and field enhancement was found for crystalline Si shell layers with thicknesses ranging from 40 to 60 nm, irradiated by a NIR laser source. On the other hand, non-conformal amorphous or crystalline shell layers with a thickness >50 nm can reach a very high local temperature (above 1000 K) when irradiated with a low power density (less than 1 mW μm-2) laser sources. This work provides a general approach for an extensive investigation of the opto-thermal properties of high-index nanoantennas.

  17. NOAA Photo Library

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes you to the Contacts page. Takes you to the HELP page. Takes you to the Credits page. Takes you to the Collections page. Takes you to the search page. Takes you to the Links page. NOAA Photo Library Image

  18. New insights on laser-induced graphene electrodes for flexible supercapacitors: tunable morphology and physical properties.

    PubMed

    Lamberti, Andrea; Perrucci, Francesco; Caprioli, Matteo; Serrapede, Mara; Fontana, Marco; Bianco, Stefano; Ferrero, Sergio; Tresso, Elena

    2017-04-28

    In certain polymers the graphenization of carbon atoms can be obtained by laser writing owing to the easy absorption of long-wavelength radiation, which generates photo-thermal effects. On a polyimide surface this process allows the formation of a nanostructured and porous carbon network known as laser-induced graphene (LIG). Herein we report on the effect of the process parameters on the morphology and physical properties of LIG nanostructures. We show that the scan speed and the frequency of the incident radiation affect the gas evolution, inducing different structure rearrangements, an interesting nitrogen self-doping phenomenon and consequently different conduction properties. The materials were characterized by infrared and Raman spectroscopy, XPS elemental analysis, electron microscopy and electrical/electrochemical measurements. In particular the samples were tested as interdigitated electrodes into electrochemical supercapacitors and the optimized LIG arrangement was tested in parallel and series supercapacitor configurations to allow power exploitation.

  19. Effect of Simulant Type on the Absorptance and Emittance of Dusted Thermal Control Surfaces in a Simulated Lunar Environment

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    2010-01-01

    During the Apollo program the effects of lunar dust on thermal control surfaces was found to be more significant than anticipated, with several systems overheating due to deposition of dust on them. In an effort to reduce risk to future missions, a series of tests has been initiated to characterize the effects of dust on these surfaces, and then to develop technologies to mitigate that risk. Given the variations in albedo across the lunar surface, one variable that may be important is the darkness of the lunar dust, and this study was undertaken to address that concern. Three thermal control surfaces, AZ-93 white paint and AgFEP and AlFEP second surface mirrors were dusted with three different lunar dust simulants in a simulated lunar environment, and their solar absorptivity and thermal emissivity values determined experimentally. The three simulants included JSC 1AF, a darker mare simulant, NU-LHT-1D, a light highlands simulant, and 1:1 mixture of the two. The response of AZ-93 was found to be slightly more pronounced than that of AgFEP. The increased with fractional dust coverage in both types of samples by a factor of 1.7 to 3.3, depending on the type of thermal control surface and the type of dust. The of the AZ-93 decreased by about 10 percent when fully covered by dust, while that of AgFEP increased by about 10 percent. It was found that alpha/epsilon varied by more than a factor of two depending on the thermal control surface and the darkness of the dust. Given that the darkest simulant used in this study may be significantly lighter than the darkest dust that could be encountered on the lunar surface, it becomes apparent that the performance degradation of thermal control surfaces due to dust on the moon will be strongly dependent on the and of the dust in the specific locality.

  20. Effect of Simulant Type on the Absorptance and Emittance of Dusted Thermal Control Surfaces in a Simulated Lunar Environment

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    2010-01-01

    During the Apollo program the effects of lunar dust on thermal control surfaces was found to be more significant than anticipated, with several systems overheating due to deposition of dust on them. In an effort to reduce risk to future missions, a series of tests has been initiated to characterize the effects of dust on these surfaces, and then to develop technologies to mitigate that risk. Given the variations in albedo across the lunar surface, one variable that may be important is the darkness of the lunar dust, and this study was undertaken to address that concern. Three thermal control surfaces, AZ-93 white paint and AgFEP and AlFEP second surface mirrors were dusted with three different lunar dust simulants in a simulated lunar environment, and their integrated solar absorptance ( ) and thermal emittance ( ) values determined experimentally. The three simulants included JSC-1AF, a darker mare simulant, NU-LHT-1D, a light highlands simulant, and 1:1 mixture of the two. The response of AZ-93 was found to be slightly more pronounced than that of AgFEP. The increased with fractional dust coverage in both types of samples by a factor of 1.7 to 3.3, depending on the type of thermal control surface and the type of dust. The of the AZ-93 decreased by about 10 percent when fully covered by dust, while that of AgFEP increased by about 10 percent. It was found that / varied by more than a factor of two depending on the thermal control surface and the darkness of the dust. Given that the darkest simulant used in this study may be lighter than the darkest dust that could be encountered on the lunar surface, it becomes apparent that the performance degradation of thermal control surfaces due to dust on the Moon will be strongly dependent on the and of the dust in the specific locality

  1. Seismic signatures of carbonate caves affected by near-surface absorptions

    NASA Astrophysics Data System (ADS)

    Rao, Ying; Wang, Yanghua

    2015-12-01

    The near-surface absorption within a low-velocity zone generally has an exponential attenuation effect on seismic waves. But how does this absorption affect seismic signatures of karstic caves in deep carbonate reservoirs? Seismic simulation and analysis reveals that, although this near-surface absorption attenuates the wave energy of a continuous reflection, it does not alter the basic kinematic shape of bead-string reflections, a special seismic characteristic associated with carbonate caves in the Tarim Basin, China. Therefore, the bead-strings in seismic profiles can be utilized, with a great certainty, for interpreting the existence of caves within the deep carbonate reservoirs and for evaluating their pore spaces. Nevertheless, the difference between the central frequency and the peak frequency is increased along with the increment in the absorption. While the wave energy of bead-string reflections remains strong, due to the interference of seismic multiples generated by big impedance contrast between the infill materials of a cave and the surrounding carbonate rocks, the central frequency is shifted linearly with respect to the near-surface absorption. These two features can be exploited simultaneously, for a stable attenuation analysis of field seismic data.

  2. Thermal Performance of an Annealed Pyrolytic Graphite Solar Collector

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Hornacek, Jennifer

    2002-01-01

    A solar collector having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity is needed for applications where solar energy is to be absorbed and transported for use in minisatellites. Such a solar collector may be used with a low temperature differential heat engine to provide power or with a thermal bus for thermal switching applications. One concept being considered for the solar collector is an Al2O3 cermet coating applied to a thermal conductivity enhanced polished aluminum substrate. The cermet coating provides high solar absorptance and the polished aluminum provides low infrared emittance. Annealed pyrolytic graphite embedded in the aluminum substrate provides enhanced thermal conductivity. The as-measured thermal performance of an annealed pyrolytic graphite thermal conductivity enhanced polished aluminum solar collector, coated with a cermet coating, will be presented.

  3. Estimation of water absorption coefficient using the TDR method

    NASA Astrophysics Data System (ADS)

    Suchorab, Zbigniew; Majerek, Dariusz; Brzyski, Przemysław; Sobczuk, Henryk; Raczkowski, Andrzej

    2017-07-01

    Moisture accumulation and transport in the building barriers is an important feature that influences building performance, causing serious exploitation problems as increased energy use, mold and bacteria growth, decrease of indoor air parameters that may lead to sick building syndrome (SBS). One of the parameters that is used to describe moisture characteristic of the material is water absorption coefficient being the measure of capillary behavior of the material as a function of time and the surface area of the specimen. As usual it is determined using gravimetric methods according to EN 1925:1999 standard. In this article we demonstrate the possibility of determination of water absorption coefficient of autoclaved aerated concrete (AAC) using the Time Domain Reflectometry (TDR) method. TDR is an electric technique that had been adopted from soil science and can be successfully used for real-time monitoring of moisture transport in building materials and envelopes. Data achieved using TDR readouts show high correlation with standard method of moisture absorptivity coefficient determination.

  4. [INVITED] Coherent perfect absorption of electromagnetic wave in subwavelength structures

    NASA Astrophysics Data System (ADS)

    Yan, Chao; Pu, Mingbo; Luo, Jun; Huang, Yijia; Li, Xiong; Ma, Xiaoliang; Luo, Xiangang

    2018-05-01

    Electromagnetic (EM) absorption is a common process by which the EM energy is transformed into other kinds of energy in the absorber, for example heat. Perfect absorption of EM with structures at subwavelength scale is important for many practical applications, such as stealth technology, thermal control and sensing. Coherent perfect absorption arises from the interplay of interference and absorption, which can be interpreted as a time-reversed process of lasing or EM emitting. It provides a promising way for complete absorption in both nanophotonics and electromagnetics. In this review, we discuss basic principles and properties of a coherent perfect absorber (CPA). Various subwavelength structures including thin films, metamaterials and waveguide-based structures to realize CPAs are compared. We also discuss the potential applications of CPAs.

  5. Enhanced photo-, sono- and sonophotocatalysis of methylene blue via SnO2 nanoparticle supported on nanographene platelets (NGP)

    NASA Astrophysics Data System (ADS)

    Paramarta, V.; Taufik, A.; Saleh, R.

    2017-07-01

    In our previous study, we have reported the catalytic (photo- and sono-) performance of SnO2 nanoparticles in methylene blue (MB) removal from aqueous solution. In this study, SnO2/nanographene platelets (NGP) composites were fabricated by depositing SnO2 nanoparticle onto nanographene platelets surface to develop photo-, sono-, and sonophotocatalysts, SnO2 nanoparticle, and SnO2/NGP composites were successfully synthesized using the sol-gel and coprecipitation method, respectively. The nanographene platelets (NGP) content was varied from 5, 10, and 15 weight percentages (wt.%). The optical properties and thermal stability of the samples were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Thermal Gravimetric Analysis (TGA). The catalytic ability of the samples was investigated using photo-, sono-, and sonophoto degradation of MB which was observed when nanographene platelets (NGP) were added into SnO2 nanocomposite. The photo-, sono- and sonophotocatalytic activities of SnO2/NGP composites on dyes were analyzed by measuring the change in absorbance of dyes under UV-spectrophotometer. The degradation of the organic dyes has been calculated by monitoring the degradation in concentration of the dyes before and after irradiation of UV light, ultrasound, and both of them respectively. The influence of other parameters such as catalyst dosage, pH, and scavenger have also been investigated. The results showed that SnO2/NGP composite with 10 weight percent (wt.%) has better catalytic performance than pure SnO2 nanoparticle. The reusability tests have also been done to ensure the stability of the used catalysts.

  6. Microwave thermal ablation: Effects of tissue properties variations on predictive models for treatment planning.

    PubMed

    Lopresto, Vanni; Pinto, Rosanna; Farina, Laura; Cavagnaro, Marta

    2017-08-01

    Microwave thermal ablation (MTA) therapy for cancer treatments relies on the absorption of electromagnetic energy at microwave frequencies to induce a very high and localized temperature increase, which causes an irreversible thermal damage in the target zone. Treatment planning in MTA is based on experimental observations of ablation zones in ex vivo tissue, while predicting the treatment outcomes could be greatly improved by reliable numerical models. In this work, a fully dynamical simulation model is exploited to look at effects of temperature-dependent variations in the dielectric and thermal properties of the targeted tissue on the prediction of the temperature increase and the extension of the thermally coagulated zone. In particular, the influence of measurement uncertainty of tissue parameters on the numerical results is investigated. Numerical data were compared with data from MTA experiments performed on ex vivo bovine liver tissue at 2.45GHz, with a power of 60W applied for 10min. By including in the simulation model an uncertainty budget (CI=95%) of ±25% in the properties of the tissue due to inaccuracy of measurements, numerical results were achieved in the range of experimental data. Obtained results also showed that the specific heat especially influences the extension of the thermally coagulated zone, with an increase of 27% in length and 7% in diameter when a variation of -25% is considered with respect to the value of the reference simulation model. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  7. Thermal lensing in ocular media

    NASA Astrophysics Data System (ADS)

    Vincelette, Rebecca Lee

    2009-12-01

    This research was a collaborative effort between the Air Force Research Laboratory (AFRL) and the University of Texas to examine the laser-tissue interaction of thermal lensing induced by continuous-wave, CW, near-infrared, NIR, laser radiation in the eye and its influence on the formation of a retinal lesion from said radiation. CW NIR laser radiation can lead to a thermal lesion induced on the retina given sufficient power and exposure duration as related to three basic parameters; the percent of transmitted energy to, the optical absorption of, and the size of the laser-beam created at the retina. Thermal lensing is a well-known phenomenon arising from the optical absorption, and subsequent temperature rise, along the path of the propagating beam through a medium. Thermal lensing causes the laser-beam profile delivered to the retina to be time dependent. Analysis of a dual-beam, multidimensional, high-frame rate, confocal imaging system in an artificial eye determined the rate of thermal lensing in aqueous media exposed to 1110, 1130, 1150 and 1318-nm wavelengths was related to the power density created along the optical axis and linear absorption coefficient of the medium. An adaptive optics imaging system was used to record the aberrations induced by the thermal lens at the retina in an artificial eye during steady-state. Though the laser-beam profiles changed over the exposure time, the CW NIR retinal damage thresholds between 1110--1319-nm were determined to follow conventional fitting algorithms which neglected thermal lensing. A first-order mathematical model of thermal lensing was developed by conjoining an ABCD beam propagation method, Beer's law of attenuation, and a solution to the heat-equation with respect to radial diffusion. The model predicted that thermal lensing would be strongest for small (< 4-mm) 1/e2 laser-beam diameters input at the corneal plane and weakly transmitted wavelengths where less than 5% of the energy is delivered to the retina

  8. Thermal Electrons in Gamma-Ray Burst Afterglows

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ressler, Sean M.; Laskar, Tanmoy

    2017-08-20

    To date, nearly all multi-wavelength modeling of long-duration γ -ray bursts has ignored synchrotron radiation from the significant population of electrons expected to pass the shock without acceleration into a power-law distribution. We investigate the effect of including the contribution of thermal, non-accelerated electrons to synchrotron absorption and emission in the standard afterglow model, and show that these thermal electrons provide an additional source of opacity to synchrotron self-absorption, and yield an additional emission component at higher energies. The extra opacity results in an increase in the synchrotron self-absorption frequency by factors of 10–100 for fiducial parameters. The nature ofmore » the additional emission depends on the details of the thermal population, but is generally observed to yield a spectral peak in the optical brighter than radiation from the nonthermal population by similar factors a few seconds after the burst, remaining detectable at millimeter and radio frequencies several days later.« less

  9. Remote activation of a microactuator using a photo-responsive nanoparticle-polymer composite

    NASA Astrophysics Data System (ADS)

    Zeberoff, Anthony

    Stimulus response materials are a class of novel materials that are currently being explored in various technologies, including biomedical devices and components, food packaging, fabrics, energy harvesting and conversion, and other elementary components such as sensors and actuators. Hybrid organic-inorganic materials such as nanoparticle-polymer composites are attractive candidates as their properties can be significantly tuned for particular applications where selectivity and localized responses are critical factors. In this work we developed and optimized a photo-responsive microactuator that can operate selectively to a specific wavelength of light. The photo-responsive microactuator is comprised of monodispersed microspheres that contain gold nanoparticles. Upon irradiation, these microspheres transduce optical energy to thermal energy, driving a localized phase change in the matrix in which they are embedded. Our remotely powered microactuator can be further realized in applications where decoupling the physical connection of the energy/control source from the actuating component is necessary.

  10. Yellowing and bleaching of grey hair caused by photo and thermal degradation.

    PubMed

    Richena, M; Silveira, M; Rezende, C A; Joekes, I

    2014-09-05

    Yellowing is an undesirable phenomenon that is common in people with white and grey hair. Because white hair has no melanin, the pigment responsible for hair colour, the effects of photodegradation are more visible in this type of hair. The origin of yellowing and its relation to photodegradation processes are not properly established, and many questions remain open in this field. In this work, the photodegradation of grey hair was investigated as a function of the wavelength of incident radiation, and its ultrastructure was determined, always comparing the results obtained for the white and black fibres present in grey hair with the results of white wool. The results presented herein indicate that the photobehaviour of grey hair irradiated with a mercury lamp or with solar radiation is dependent on the wavelength range of the incident radiation and on the initial shade of yellow in the sample. Two types of grey hair were used: (1) blended grey hair (more yellow) and (2) grey hair from a single-donor (less yellow). After exposure to a full-spectrum mercury lamp for 200 h, the blended white hair turned less yellow (the yellow-blue difference, Db(*) becomes negative, Db(*)=-6), whereas the white hair from the single-donor turned slightly yellower (Db(*)=2). In contrast, VIS+IR irradiation resulted in bleaching in both types of hair, whereas a thermal treatment (at 81 °C) caused yellowing of both types of hair, resulting in a Db(*)=3 for blended white hair and Db(*)=9 for single-donor hair. The identity of the yellow chromophores was investigated by UV-Vis spectroscopy. The results obtained with this technique were contradictory, however, and it was not possible to obtain a simple correlation between the sample shade of yellow and the absorption spectra. In addition, the results are discussed in terms of the morphology differences between the pigmented and non-pigmented parts of grey hair, the yellowing and bleaching effects of grey hair, and the occurrence of dark

  11. Training and business performance: the mediating role of absorptive capacities.

    PubMed

    Hernández-Perlines, Felipe; Moreno-García, Juan; Yáñez-Araque, Benito

    2016-01-01

    Training has been the focus of considerable conceptual and empirical attention but is considered a relevant factor for competitive edge in companies because it has a positive impact on business performance. This study is justified by the need for deeper analysis of the process involving the transfer of training into performance. This paper's originality lies in the implementation of the absorptive capacities approach as an appropriate conceptual framework for designing a model that reflects the connection between training and business performance through absorptive capacities. Based on the above conceptual framework and using the dual methodological implementation, a new method of analyzing the relationship between training and performance was obtained: efforts in training will not lead to performance without the mediation of absorptive. Training turns into performance if absorptive capacities are involved in this process. The suggested model becomes an appropriate framework for explaining the process of transformation of training into organizational performance, in which absorptive capacities play a key role. The findings obtained can go further owing to fs/QCA: of the different absorptive capacities, that of exploitation is a necessary condition to achieve better organizational performance. Therefore, training based on absorptive capacity will guide and facilitate the design of appropriate human resource strategies so that training results in improved performance. This conclusion is relevant for the development of a new facet of absorptive capacities by relating it to training and resulting in first-level implications for human resource management.

  12. Ultrafast photo-induced hidden phases in strained manganite thin films

    NASA Astrophysics Data System (ADS)

    Zhang, Jingdi; McLeod, A. S.; Zhang, Gu-Feng; Stoica, Vladimir; Jin, Feng; Gu, Mingqiang; Gopalan, Venkatraman; Freeland, John W.; Wu, Wenbin; Rondinelli, James; Wen, Haidan; Basov, D. N.; Averitt, R. D.

    Correlated transition metal oxides (TMOs) are particularly sensitive to external control because of energy degeneracy in a complex energy landscape that promote a plethora of metastable states. However, it remains a grand challenge to actively control and fully explore the rich landscape of TMOs. Dynamic control with pulsed photons can overcome energetic barriers, enabling access to transient or metastable states that are not thermally accessible. In the past, we have demonstrated that mode-selective single-laser-pulse excitation of a strained manganite thin film La2/3Ca1/3MnO3 initiates a persistent phase transition from an emergent antiferromagnetic insulating ground state to a ferromagnetic metallic metastable state. Beyond the photo-induced insulator to metal transition, we recently discovered a new peculiar photo-induced hidden phase, identified by an experimental approach that combines ultrafast pump-probe spectroscopy, THz spectroscopy, X-ray diffraction, cryogenic near-field spectroscopy and SHG probe. This work is funded by the DOE, Office of Science, Office of Basic Energy Science under Award Numbers DE-SC0012375 and DE-SC0012592.

  13. Spatial nonlinear absorption of Alfven waves by dissipative plasma taking account bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Taiurskii, A. A.; Gavrikov, M. B.

    2016-10-01

    We study numerically the nonlinear absorption of a plane Alfven wave falling on the stationary boundary of dissipative plasma. This absorption is caused by such factors as the magnetic viscosity, hydrodynamic viscosity, and thermal conductivity of electrons and ions, bremsstrahlung and energy exchange between plasma components. The relevance of this investigation is due to some works, published in 2011, with regard to the heating mechanism of the solar corona and solar wind generation as a result of the absorption of plasma Alfven waves generated in the lower significantly colder layers of the Sun. Numerical analysis shows that the absorption of Alfven waves occurs at wavelengths of the order of skin depth, in which case the classical MHD equations are inapplicable. Therefore, our research is based on equations of two-fluid magnetohydrodynamics that take into account the inertia of the electrons. The implicit difference scheme proposed here for calculating plane-parallel flows of two-fluid plasma reveals a number of important patterns of absorption and thus allows us to study the dependence of the absorption on the Alfven wave frequency and the electron thermal conductivity and viscosity, as well as to evaluate the depth and the velocity of plasma heating during the penetration of Alfven waves interacting with dissipative plasma.

  14. Non-destructive evaluation of UV pulse laser-induced damage performance of fused silica optics.

    PubMed

    Huang, Jin; Wang, Fengrui; Liu, Hongjie; Geng, Feng; Jiang, Xiaodong; Sun, Laixi; Ye, Xin; Li, Qingzhi; Wu, Weidong; Zheng, Wanguo; Sun, Dunlu

    2017-11-24

    The surface laser damage performance of fused silica optics is related to the distribution of surface defects. In this study, we used chemical etching assisted by ultrasound and magnetorheological finishing to modify defect distribution in a fused silica surface, resulting in fused silica samples with different laser damage performance. Non-destructive test methods such as UV laser-induced fluorescence imaging and photo-thermal deflection were used to characterize the surface defects that contribute to the absorption of UV laser radiation. Our results indicate that the two methods can quantitatively distinguish differences in the distribution of absorptive defects in fused silica samples subjected to different post-processing steps. The percentage of fluorescence defects and the weak absorption coefficient were strongly related to the damage threshold and damage density of fused silica optics, as confirmed by the correlation curves built from statistical analysis of experimental data. The results show that non-destructive evaluation methods such as laser-induced fluorescence and photo-thermal absorption can be effectively applied to estimate the damage performance of fused silica optics at 351 nm pulse laser radiation. This indirect evaluation method is effective for laser damage performance assessment of fused silica optics prior to utilization.

  15. Analogies and differences among bacterial and viral disinfection by the photo-Fenton process at neutral pH: a mini review.

    PubMed

    Giannakis, Stefanos

    2017-12-19

    Over the last years, the photo-Fenton process has been established as an effective, green alternative to chemical disinfection of waters and wastewaters. Microorganisms' inactivation is the latest success story in the application of this process at near-neutral pH, albeit without clearly elucidated inactivation mechanisms. In this review, the main pathways of the combined photo-Fenton process against the most frequent pathogen models (Escherichia coli for bacteria and MS2 bacteriophage for viruses) are analyzed. Firstly, the action of solar light is described and the specific inactivation mechanisms in bacteria (internal photo-Fenton) and viruses (genome damage) are presented. The contribution of the external pathways due to the potential presence of organic matter in generating reactive oxygen species (ROS) and their effects on microorganism inactivation are discussed. Afterwards, the effects of the gradual addition of Fe and H 2 O 2 are assessed and the differences among bacterial and viral inactivation are highlighted. As a final step, the simultaneous addition of both reagents induces the photo-Fenton in the bulk, focusing on the differences induced by the homogeneous or heterogeneous fraction of the process and the variation among the two respective targets. This work exploits the accumulated evidence on the mechanisms of bacterial inactivation and the scarce ones towards viral targets, aiming to bridge this knowledge gap and make possible the further application of the photo-Fenton process in the field of water/wastewater treatment.

  16. Laser Absorption by Over-Critical Plasmas

    NASA Astrophysics Data System (ADS)

    May, J.; Tonge, J.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.

    2015-11-01

    Absorption of high intensity laser light by matter has important applications to emerging sciences and technology, such as Fast Ignition ICF and ion acceleration. As such, understanding the underlying mechanisms of this absorption is key to developing these technologies. Critical features which distinguish the interaction of high intensity light - defined here as a laser field having a normalized vector potential greater than unity - are that the reaction of the material to the fields results in sharp high-density interfaces; and that the movement of the electrons is in general relativistic, both in a fluid and a thermal sense. The results of these features are that the absorption mechanisms are qualitatively distinct from those at lower intensities. We will review previous work, by our group and others, on the absorption mechanisms, and highlight current research. We will show that the standing wave structure of the reflected laser light is key to particle dynamics for normally incident lasers. The authors acknowledge the support of the Department of Energy under contract DE-NA 0001833 and the National Science Foundation under contract ACI 1339893.

  17. Management of light absorption in extraordinary optical transmission based ultra-thin-film tandem solar cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mashooq, Kishwar; Talukder, Muhammad Anisuzzaman, E-mail: anis@eee.buet.ac.bd

    2016-05-21

    Although ultra-thin-film solar cells can be attractive in reducing the cost, they suffer from low absorption as the thickness of the active layer is usually much smaller than the wavelength of incident light. Different nano-photonic techniques, including plasmonic structures, are being explored to increase the light absorption in ultra-thin-film solar cells. More than one layer of active materials with different energy bandgaps can be used in tandem to increase the light absorption as well. However, due to different amount of light absorption in different active layers, photo-generated currents in different active layers will not be the same. The current mismatchmore » between the tandem layers makes them ineffective in increasing the efficiency. In this work, we investigate the light absorption properties of tandem solar cells with two ultra-thin active layers working as two subcells and a metal layer with periodically perforated holes in-between the two subcells. While the metal layer helps to overcome the current mismatch, the periodic holes increase the absorption of incident light by helping extraordinary optical transmission of the incident light from the top to the bottom subcell, and by coupling the incident light to plasmonic and photonic modes within ultra-thin active layers. We extensively study the effects of the geometry of holes in the intermediate metal layer on the light absorption properties of tandem solar cells with ultra-thin active layers. We also study how different metals in the intermediate layer affect the light absorption; how the geometry of holes in the intermediate layer affects the absorption when the active layer materials are changed; and how the intermediate metal layer affects the collection of photo-generated electron-hole pairs at the terminals. We find that in a solar cell with 6,6-phenyl C61-butyric acid methyl ester top subcell and copper indium gallium selenide bottom subcell, if the periodic holes in the metal layer are

  18. NOAA Photo Library - Contacts

    Science.gov Websites

    NOAA Photo Library Banner Takes you to the Top Page Takes you to the About this Site page. Takes concerning this site, please contact: NOAA Photo Library NOAA Central Library Email: photolibrary@noaa.gov Library NOAA Privacy Policy | NOAA Disclaimer Last Updated: September 30, 2009

  19. Enhanced absorption in two-dimensional materials via Fano-resonant photonic crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Wenyi; Klots, Andrey; Bolotin, Kirill I.

    2015-05-04

    The use of two-dimensional (2D) materials in optoelectronics has attracted much attention due to their fascinating optical and electrical properties. However, the low optical absorption of 2D materials arising from their atomic thickness limits the maximum attainable external quantum efficiency. For example, in the visible and near-infrared regimes monolayer MoS{sub 2} and graphene absorb only ∼10% and 2.3% of incoming light, respectively. Here, we experimentally demonstrate the use of Fano-resonant photonic crystals to significantly boost absorption in atomically thin materials. Using graphene as a test bed, we demonstrate that absorption in the monolayer thick material can be enhanced to 77%more » within the telecommunications band, the highest value reported to date. We also show that the absorption in the Fano-resonant structure is non-local, with light propagating up to 16 μm within the structure. This property is particularly beneficial in harvesting light from large areas in field-effect-transistor based graphene photodetectors in which separation of photo-generated carriers only occurs ∼0.2 μm adjacent to the graphene/electrode interface.« less

  20. Degradation of thermal control materials under a simulated radiative space environment

    NASA Astrophysics Data System (ADS)

    Sharma, A. K.; Sridhara, N.

    2012-11-01

    A spacecraft with a passive thermal control system utilizes various thermal control materials to maintain temperatures within safe operating limits. Materials used for spacecraft applications are exposed to harsh space environments such as ultraviolet (UV) and particle (electron, proton) irradiation and atomic oxygen (AO), undergo physical damage and thermal degradation, which must be considered for spacecraft thermal design optimization and cost effectiveness. This paper describes the effect of synergistic radiation on some of the important thermal control materials to verify the assumptions of beginning-of-life (BOL) and end-of-life (EOL) properties. Studies on the degradation in the optical properties (solar absorptance and infrared emittance) of some important thermal control materials exposed to simulated radiative geostationary space environment are discussed. The current studies are purely related to the influence of radiation on the degradation of the materials; other environmental aspects (e.g., thermal cycling) are not discussed. The thermal control materials investigated herein include different kind of second-surface mirrors, white anodizing, white paints, black paints, multilayer insulation materials, varnish coated aluminized polyimide, germanium coated polyimide, polyether ether ketone (PEEK) and poly tetra fluoro ethylene (PTFE). For this purpose, a test in the constant vacuum was performed reproducing a three year radiative space environment exposure, including ultraviolet and charged particle effects on North/South panels of a geostationary three-axis stabilized spacecraft. Reflectance spectra were measured in situ in the solar range (250-2500 nm) and the corresponding solar absorptance values were calculated. The test methodology and the degradations of the materials are discussed. The most important degradations among the low solar absorptance materials were found in the white paints whereas the rigid optical solar reflectors remained quite

  1. Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

    PubMed

    Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

    2012-12-21

    In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

  2. Lanthanum fluoride upconverting nanoparticles for photo-biomodulation of cell function

    NASA Astrophysics Data System (ADS)

    Tek, Sumeyra; Vincent, Brandy K.; Mimun, L. Christopher; Tran, Ashley N.; Shrestha, Binita; Tang, Liang; Nash, Kelly L.

    2017-02-01

    Inorganic fluorescent nanoprobes have been widely used as passive agents for intracellular imaging for decades. An emerging field of research is the development of these contrast agents and using them actively in a way that they respond to external stimulation by inducing photo-chemical, thermal or mechanical actions that enable control and modulation over cell function. To achieve such control, methods which are remote, non-invasive and with low-thermal means of stimulation is preferable. Among a large variety of candidates, lanthanide doped upconverting nanoparticles (UCNPs) are one of the most interesting class of fluorescent materials. Non-scattering, low energy near infrared (NIR) light can be used for excitation of UCNPs as on-demand light sources resulting in emission peaks throughout the near-UV and visible wavelengths. Towards this goal, we developed nano-size, hydrophilic, non-toxic and biocompatible core-shell nanoparticles with enhanced upconversion intensity for photo-biomodulation studies. Under this approach, un-doped LaF3 (inert) shell and Yb3+ doped LaF3 (active) shell are grown on core LaF3:20% Yb, 2% Tm upconverting nanoparticles for enhanced luminescence for the first time with rapid microwave-assisted synthesis method that employs Polyvinylpyrrolidone (PVP) as biocompatible surfactant. The as-synthesized high efficiency UCNPs are analyzed through XRD, TEM, HRTEM, and Photoluminescence spectrum that is acquired under 980 nm laser excitation. Confocal microscopy is used to visualize nanoparticles in cells. The cellular response to NIR irradiation and upconverted light are visualized by luminescence microscopy.

  3. Laser engines operating by resonance absorption.

    PubMed

    Garbuny, M; Pechersky, M J

    1976-05-01

    The coherence properties and power levels of lasers available at present lend themselves to the remote operation of mechanical engines by resonance absorption in a working gas. Laser radiation is capable of producing extremely high temperatures in a gas. Limits to the achievable temperatures in the working gas of an engine are imposed by the solid walls and by loss of resonance absorption due to thermal saturation, bleaching, and dissociation. However, it is shown that by proper control of the laser beam in space, time, and frequency, as well as by choice of the absorbing gas, these limits are to a great extent removed so that very high temperatures are indeed attainable. The working gas is largely monatomic, preferably helium with the addition of a few volume percent of an absorber. Such a gas mixture, internally heated, permits an optimization of the expansion ratio, with resulting thermal efficiencies and work ratios, not achievable in conventional engines. A relationship between thermal efficiency and work ratio is derived that is quite general for the optimization condition. The performance of laser piston engines, turbines, and the Stirling cycle based on these principles is discussed and compared with conventional engine operation. Finally, a brief discussion is devoted to the possibility and concepts for the direct conversion of selective vibrational or electronic excitation into mechanical work, bypassing the translational degrees of freedom.

  4. Content-aware automatic cropping for consumer photos

    NASA Astrophysics Data System (ADS)

    Tang, Hao; Tretter, Daniel; Lin, Qian

    2013-03-01

    Consumer photos are typically authored once, but need to be retargeted for reuse in various situations. These include printing a photo on different size paper, changing the size and aspect ratio of an embedded photo to accommodate the dynamic content layout of web pages or documents, adapting a large photo for browsing on small displays such as mobile phone screens, and improving the aesthetic quality of a photo that was badly composed at the capture time. In this paper, we propose a novel, effective, and comprehensive content-aware automatic cropping (hereafter referred to as "autocrop") method for consumer photos to achieve the above purposes. Our autocrop method combines the state-of-the-art context-aware saliency detection algorithm, which aims to infer the likely intent of the photographer, and the "branch-and-bound" efficient subwindow search optimization technique, which seeks to locate the globally optimal cropping rectangle in a fast manner. Unlike most current autocrop methods, which can only crop a photo into an arbitrary rectangle, our autocrop method can automatically crop a photo into either a rectangle of arbitrary dimensions or a rectangle of the desired aspect ratio specified by the user. The aggressiveness of the cropping operation may be either automatically determined by the method or manually indicated by the user with ease. In addition, our autocrop method is extended to support the cropping of a photo into non-rectangular shapes such as polygons of any number of sides. It may also be potentially extended to return multiple cropping suggestions, which will enable the creation of new photos to enrich the original photo collections. Our experimental results show that the proposed autocrop method in this paper can generate high-quality crops for consumer photos of various types.

  5. Fast photo-induced color changes of Ag particles deposited on single-crystalline TiO2 surface

    NASA Astrophysics Data System (ADS)

    Bai, Y. J.; Liu, W. Z.; Chen, A.; Shi, L.; Liu, X. H.; Zi, J.

    2018-05-01

    It is well known that surface-plasmon enhanced photo-electrochemical effect or photo-thermal effect of metallic particles on a semiconductor substrate or in a suspension may result in color changes. Such character could be potentially applicable to colorimetric sensors, optical filters, and data storage devices. However, usually the response time for color changes is too long to be practically applied. In this letter, we found that the response rate of color changes could be controlled by the annealing condition of the semiconductor substrate, and changes larger than 10% in spectra were observed after only 1-min exposure to light. Furthermore, such fast response was applied to realize wavelength-dependent "write" and "read" applications with high spatial resolution.

  6. Exploitation of dark fermented effluent of cheese whey by co-culture of Rhodobacter sphaeroides and Bacillus firmus for photo-hydrogen production.

    PubMed

    Pandey, A; Pandey, A

    2017-07-31

    In this study photo-hydrogen production from cheese whey dark fermentation (DF) effluent by the co-culture of Rhodobacter sphaeroides -NMBL-01 and Bacillus firmus - NMBL-03 has been reported. The effect of pH, initial chemical oxygen demand (COD) and the concentration effect of FeSO4.7H2O on photo-hydrogen production have been investigated. The end products of dark fermentation effluent of cheese whey were mainly comprised of soluble organic acids, i.e. butyric acid and lactic acid. The batch process was carried out under light intensity of 2.5 kLux at 32 ± 2oC without any addition of extra carbon and nitrogen source. The single parameter optimization studies revealed optimum pH 6.5, initial COD 4.71 g/L and supplementation of Fe2+ concentration 100 mg/L. The maximum cumulative hydrogen production and yield were found to be 469 ± 45.8 ml H2/L and 146.56 ± 14.31 ml H2/g COD reduced (67.9% reduction in COD) respectively. The mutual interactions among the process parameters were also investigated by three factorial Box-Behnken design of response surface methodology. The optimized experimental values were found concurrent with the calculated values obtained from the theoretical model.

  7. UV-responsive nano-sponge for oil absorption and desorption

    PubMed Central

    Kim, Do Hyun; Jung, Min Chan; Cho, So-Hye; Kim, Sang Hoon; Kim, Ho-Young; Lee, Heon Ju; Oh, Kyu Hwan; Moon, Myoung-Woon

    2015-01-01

    Controlled surface wettability for oil has been intensively studied to remove industrial oil waste or oil spill pollution from seas or rivers. In particular, external stimuli-induced special wetting materials, such as photo-responsive TiO2, have attracted considerable attention for oil-water separation. In this study, a novel method is reported to fabricate a nano-sponge which is composed of hydrophobic hydrocarbon and hydrophilic TiO2 nanoparticles for oil absorption or desorption that are responsive to UV irradiation. The hydrocarbon in the nano-sponge could selectively absorb oil from water, whereas the absorbed oil is released into the water by TiO2 in response to UV irradiation. The nano-sponge functionalized porous polydimethylsiloxane released more than 98% of the absorbed crude oil with UV irradiation and air-bubbling. It could be continuously reused while maintaining a high absorption capacity and desorption efficiency without incurring secondary air or water pollution. This smart oil absorption/desorption methodology with excellent selectivity and recyclability with almost perfect removal of absorbed oil can be applied for oil-water separation, oil spill cleanup and reuse of spilled oil. PMID:26260470

  8. Photo- and gas-tuned, reversible thermoelectric properties and anomalous photo-thermoelectric effects of platinum-loaded tungsten trioxide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Suzuki, Kenta; Watanabe, Takuya; Kakemoto, Hirofumi

    We report the photo- and gas-controllable properties of platinum-loaded tungsten trioxide (Pt/WO{sub 3}), which is of interest for developing practical applications of WO{sub 3} as well as for interpreting such phenomena from scientific viewpoints. Here, a Pt/WO{sub 3} thin film generated a thermoelectric power due to the ultraviolet-light-induced band-gap excitation (photochromic (PC) reaction) and/or dark storage in formic acid vapor (gaschromic (GC) reaction) in the absence of O{sub 2}, resulting from the generation of W{sup 5+} ions. After such chromic reactions, the electrical conductivity (σ) is increased, whereas the absolute value of the Seebeck coefficient (S) is decreased. The changesmore » in σ and S and their rate of change for consistency increased in the order of: during the PC reaction < during the GC reaction < during simultaneous PC and GC reactions. The opposite behaviors, a decrease in σ and an increase in S, were exhibited by Pt/WO{sub 3} in the presence of O{sub 2} after dark storage or visible-light irradiation. This reversible cycle could be repeated. Moreover, anomalous, nontrivial photo-thermoelectric effects (a photoconductive effect (photoconductivity, σ{sub photo}) and a photo-Seebeck effect (photo-Seebeck coefficient, S{sub photo})) were also detected in response to the visible-light irradiation of Pt/WO{sub 3} in the absence of O{sub 2} after chromic reactions. Under visible-light irradiation, both σ{sub photo} and the absolute value of S{sub photo} are increased. After the irradiation, both values were decreased, that is, σ and the absolute value of S were smaller than σ{sub photo} and the absolute value of S{sub photo}, respectively. These effects are likely to be due to the photoinduced charge carriers and the accumulated electrons in Pt contributing to the increase in σ{sub photo}. In addition, electrons are extracted from the W{sup 5+} state, decreasing the number of W{sup 5+} in H{sub x}WO{sub 3} and thus contributing

  9. Phase change material thermal capacitor clothing

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    2005-01-01

    An apparatus and method for metabolic cooling and insulation of a user in a cold environment. In its preferred embodiment the apparatus is a highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The apparatus can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The apparatus may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the apparatus also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  10. A perceptual metric for photo retouching.

    PubMed

    Kee, Eric; Farid, Hany

    2011-12-13

    In recent years, advertisers and magazine editors have been widely criticized for taking digital photo retouching to an extreme. Impossibly thin, tall, and wrinkle- and blemish-free models are routinely splashed onto billboards, advertisements, and magazine covers. The ubiquity of these unrealistic and highly idealized images has been linked to eating disorders and body image dissatisfaction in men, women, and children. In response, several countries have considered legislating the labeling of retouched photos. We describe a quantitative and perceptually meaningful metric of photo retouching. Photographs are rated on the degree to which they have been digitally altered by explicitly modeling and estimating geometric and photometric changes. This metric correlates well with perceptual judgments of photo retouching and can be used to objectively judge by how much a retouched photo has strayed from reality.

  11. Measurement and compensation of wavefront deformations and focal shifts in high-power laser optics

    NASA Astrophysics Data System (ADS)

    Mann, K.; Schäfer, B.; Stubenvoll, M.; Hentschel, K.; Zenz, M.

    2015-11-01

    We demonstrate the feasibility of passive compensation of the thermal lens effect in fused silica optics, placing suitable optical materials with negative dn/dT in the beam path of a high power near IR fiber laser. Following a brief overview of the involved mechanisms, photo-thermal absorption measurements with a Hartmann-Shack sensor are described, from which coefficients for surface/coating and bulk absorption in various materials are determined. Based on comprehensive knowledge of the 2D wavefront deformations resulting from absorption, passive compensation of thermally induced aberrations in complex optical systems is possible, as illustrated for an F-Theta objective. By means of caustic measurements during high-power operation we are able to demonstrate a 60% reduction of the focal shift in F-Theta lenses through passive compensation.

  12. Electromagnetic absorption behaviour of ferrite loaded three phase carbon fabric composites

    NASA Astrophysics Data System (ADS)

    Jagatheesan, Krishnasamy; Ramasamy, Alagirusamy; Das, Apurba; Basu, Ananjan

    2018-02-01

    This article investigates the electromagnetic absorption behaviours of carbon helical yarn fabric reinforced composites and manganese-zinc (Mn-Zn) ferrite particles loaded 3 phase fabric composites. A carbon helical yarn having stainless steel core was prepared and made into single jersey knitted fabric. The composite was prepared by sandwiching a fabric with polypropylene films and thermal pressed. The absorption values of helical yarn fabric composite was observed to be less in the C band region (4-8 GHz). For improving the absorption coefficients of composite, Mn-Zn ferrite particles were dispersed in the polypropylene (PP) composite. The ferrite loaded PP composites exhibited better permittivity and permeability values, hence the absorption loss of the composite was improved. The helical yarn fabric reinforced with Mn-Zn ferrite/PP composite showed larger absorption coefficients than virgin PP/fabric composite. The change in thermal stability and particle size distribution in the Mn-Zn ferrite/PP composite was also analyzed. At higher ferrite concentration, bimodal particle distribution was observed which increased the conductivity and shielding effectiveness (SE) of the composite. In addition, complex permittivity value was also increased for higher incident frequency (4-8 GHz). As the ferrite content increases, the dielectric loss and magnetic permeability of PP/ferrite increases due to increased magnetic loss. Hence, ferrite loaded PP composite showed the total SE of -14.2 dB with the absorption coefficients of 0.717. The S1C7 fabric composite having ferrite dispersion showed the better absorption loss and lower reflection coefficient of 14.2 dB and 0.345 respectively compared to virgin PP/helical yarn fabric composite. The increasing ferrite content (45 wt%) improved the absorption loss and total SE. Though, ferrite based fabric composite exhibits moderate absorptive shielding, it can be used as shielding panels in the electronic industries.

  13. A short cut for scaling aerial photos

    Treesearch

    Earl J. Rogers

    1948-01-01

    Aerial photos are a handy tool for the forester. They furnish forest data quickly. But when the photo is used as a map, care is necessary - especially in rough country. In flat country photo scales are quite uniform and distances can be measured accurately. But in rough country photo scale varies with changes in elevation, and it is more difficult to measure distances...

  14. Two-photon absorption dispersion spectrometer for 1.53 μm eye-safe Doppler LIDAR.

    PubMed

    Vance, J D

    2012-07-01

    Based upon resonant two-photon absorption within a rubidium cell and 780 nm pump light, a birefringent medium for 1.530 μm is induced that changes rapidly with frequency. The birefringence is exploited to build a spectrometer that is capable of measuring the Doppler shift of scattered photons.

  15. Dental enamel irradiated with infrared diode laser and photo-absorbing cream: part 2--EDX study.

    PubMed

    de Sant'Anna, Giselle Rodrigues; dos Santos, Edson Aparecido Pereira; Soares, Luís Eduardo Silva; do Espírito Santo, Ana Maria; Martin, Airton Abrahão; Duarte, Danilo Antônio; Pacheco-Soares, Cristina; Brugnera, Aldo

    2009-10-01

    The effects of laser-induced compositional changes on the enamel were investigated by energy-dispersive X-ray fluorescence spectrometry (micro-EDX). After cariogenic challenge, we administered treatment of low-level infrared diode laser and a photo-absorbing cream (used to intensify the superficial light absorption). Dental caries is considered the most prevalent oral disease. A simple and noninvasive caries preventive regimen is treating tooth enamel with a laser, either alone or in combination with fluoride, which reduces enamel solubility and dissolution rates. High power lasers are still not widely used in private practice. Low-power near-infrared lasers may be an alternative approach. Energy-dispersive micro-EDX is a versatile and nondestructive spectroscopic technique that allows for a qualitative and quantitative elemental analysis of inorganic enamel components, such as calcium and phosphorus. Twenty-four extracted or exfoliated caries-free deciduous molars were divided into six groups: 1) control group (CTR-no treatment); 2) infrared laser treatment (L) (lambda = 810 nm, 100 mW/cm(2), 90 sec, 4.47 J/cm(2), 9 J); 3) infrared laser irradiation and photo-absorbing agent (CL); 4) photo-absorbing agent alone (C); 5) infrared laser irradiation and fluoridated photo-absorbing agent (FCL); and 6) fluoridated photo-absorbing agent alone (FC). Samples were analyzed using micro-EDX after two sets of treatments and pH cycling cariogenic challenges. The CL group showed statistically significant increases in calcium and phosphorus (wt%) compared with the CTR group. The Ca/P ratio was similar in the FCL and CTR groups. There was a significant laser-induced reduction compared with the CTR group, and there was a possible modification of the organic balance content in enamel treated with laser and cream. micro-EDX may be able to detect compositional changes in mineral phases of lased enamel under cariogenic challenge. Our results suggest that with a combined laser and photo

  16. Thermal effects of X-band microwaves on skin tissues

    NASA Astrophysics Data System (ADS)

    Song, Kyo D.; Yoon, Hargsoon; Lee, Kunik; Kim, Jaehwan; Choi, Sang H.

    2012-04-01

    Microwave can be used as a power carrier to implanted medical devices wirelessly, which is regarded as one of the attractive features for medical applications. The loss mechanism of microwave transmission through lossy media often appears as a thermal effect due to the absorption of microwave. Such a thermal effect on human tissue has not rigorously studied yet. The thermal effect on living tissues was experimentally tested with animal skins to understand the absorption characteristics of microwave. In this paper, the frequency range of microwave used for the tests was from 6 GHz to 13 GHz.

  17. Frequency up-shift in the stimulated thermal scattering under two-photon absorption in liquids and colloids of metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Smetanin, I. V.; Erokhin, A. I.; Baranov, A. N.

    2018-07-01

    We report the results of the experimental and theoretical study of stimulated temperature scattering in toluene and hexane solutions of Ag-nanoparticles, as well as in pure toluene in the two-photon absorption regime. A four-wave mixing scheme with two counter-propagating pump waves of the same frequency is utilised to demonstrate the lasing effect and the amplification of the backscattered anti-Stokes signal. For the first time, we have measured anti-Stokes spectral shifts which turn out to appreciably exceed the Rayleigh line widths in those liquids. It is shown that the amplification effect is provided predominantly by thermally induced coherent polarisation oscillations, while the dynamic interference temperature grating causes the formation of a self-induced optical cavity inside the interaction region.

  18. Reversible photo-induced trap formation in mixed-halide hybrid perovskites for photovoltaics.

    PubMed

    Hoke, Eric T; Slotcavage, Daniel J; Dohner, Emma R; Bowring, Andrea R; Karunadasa, Hemamala I; McGehee, Michael D

    2015-01-01

    We report on reversible, light-induced transformations in (CH 3 NH 3 )Pb(Br x I 1- x ) 3 . Photoluminescence (PL) spectra of these perovskites develop a new, red-shifted peak at 1.68 eV that grows in intensity under constant, 1-sun illumination in less than a minute. This is accompanied by an increase in sub-bandgap absorption at ∼1.7 eV, indicating the formation of luminescent trap states. Light soaking causes a splitting of X-ray diffraction (XRD) peaks, suggesting segregation into two crystalline phases. Surprisingly, these photo-induced changes are fully reversible; the XRD patterns and the PL and absorption spectra revert to their initial states after the materials are left for a few minutes in the dark. We speculate that photoexcitation may cause halide segregation into iodide-rich minority and bromide-enriched majority domains, the former acting as a recombination center trap. This instability may limit achievable voltages from some mixed-halide perovskite solar cells and could have implications for the photostability of halide perovskites used in optoelectronics.

  19. Ground-based photo monitoring

    Treesearch

    Frederick C. Hall

    2000-01-01

    Ground-based photo monitoring is repeat photography using ground-based cameras to document change in vegetation or soil. Assume those installing the photo location will not be the ones re-photographing it. This requires a protocol that includes: (1) a map to locate the monitoring area, (2) another map diagramming the photographic layout, (3) type and make of film such...

  20. Targeted two-photon PDT photo-sensitizers for the treatment of subcutaneous tumors

    NASA Astrophysics Data System (ADS)

    Spangler, C. W.; Rebane, A.; Starkey, J.; Drobizhev, M.

    2009-06-01

    New porphyrin-based photo-sensitizers have been designed, synthesized and characterized that exhibit greatly enhanced intrinsic two-photon absorption. These new photo-sensitizers have been incorporated into triad formulations that also incorporate Near-infrared (NIR) imaging agents, and small-molecule targeting agents that direct the triads to cancerous tumors' over-expressed receptor sites. PDT can be initiated deep into the tissue transparency window at 780-800 nm utilizing a regeneratively amplified Ti:sapphire laser using 100-150 fs pulses of 600-800 mW. Human tumor xenografts of human breast cancer (MDA-MB-231) and both small SCLC (NCI-H69) and NSCLC (A-459) have been successfully treated using octreotate targeting of over-expressed SST2 receptors. In particular, the lung cancer xenografts can be successfully treated by irradiating from the side of the mouse opposite the implanted tumor, thereby passing through ca. 2 cm of mouse skin, tissue and organs with no discernible damage to healthy tissue while causing regression in the tumors. These results suggest a new PDT paradigm for the noninvasive treatment of subcutaneous tumors, including the possibility that the targeting moiety could be matched to individual patient genetic profiles (patient-specific therapeutics).

  1. A Comparative Analysis of the Photo-Protective Effects of Soy Isoflavones in Their Aglycone and Glucoside Forms

    PubMed Central

    Iovine, Barbara; Iannella, Maria Luigia; Gasparri, Franco; Giannini, Valentina; Monfrecola, Giuseppe; Bevilacqua, Maria Assunta

    2012-01-01

    Isoflavones exist in nature predominantly as glucosides such as daidzin or genistin and are rarely found in their corresponding aglycone forms daidzein and genistein. The metabolism and absorption of isoflavones ingested with food is well documented, but little is known about their use as topical photo-protective agents. The aim of this study was to investigate in a comparative analysis the photo-protective effects of isoflavones in both their aglycone and glucoside forms. In human skin fibroblasts irradiated with 60 mJ/cm2 ultraviolet B (UVB), we measured the expression levels of COX-2 and Gadd45, which are involved in inflammation and DNA repair, respectively. We also determined the cellular response to UVB-induced DNA damage using the comet assay. Our findings suggest that both the isoflavone glucosides at a specific concentration and combination with an aglycone mixture exerted an anti-inflammatory and photo-protective effect that prevented 41% and 71% of UVB-induced DNA damage, respectively. The advantages of using either isoflavone glucosides or an aglycone mixture in applications in the field of dermatology will depend on their properties and their different potential uses. PMID:23211668

  2. Influence of Nitrogen Doping on Device Operation for TiO₂-Based Solid-State Dye-Sensitized Solar Cells: Photo-Physics from Materials to Devices.

    PubMed

    Wang, Jin; Tapio, Kosti; Habert, Aurélie; Sorgues, Sebastien; Colbeau-Justin, Christophe; Ratier, Bernard; Scarisoreanu, Monica; Toppari, Jussi; Herlin-Boime, Nathalie; Bouclé, Johann

    2016-02-23

    Solid-state dye-sensitized solar cells (ssDSSC) constitute a major approach to photovoltaic energy conversion with efficiencies over 8% reported thanks to the rational design of efficient porous metal oxide electrodes, organic chromophores, and hole transporters. Among the various strategies used to push the performance ahead, doping of the nanocrystalline titanium dioxide (TiO₂) electrode is regularly proposed to extend the photo-activity of the materials into the visible range. However, although various beneficial effects for device performance have been observed in the literature, they remain strongly dependent on the method used for the production of the metal oxide, and the influence of nitrogen atoms on charge kinetics remains unclear. To shed light on this open question, we synthesized a set of N-doped TiO₂ nanopowders with various nitrogen contents, and exploited them for the fabrication of ssDSSC. Particularly, we carefully analyzed the localization of the dopants using X-ray photo-electron spectroscopy (XPS) and monitored their influence on the photo-induced charge kinetics probed both at the material and device levels. We demonstrate a strong correlation between the kinetics of photo-induced charge carriers probed both at the level of the nanopowders and at the level of working solar cells, illustrating a direct transposition of the photo-physic properties from materials to devices.

  3. Composite Reflective Absorptive IR-Blocking Filters Embedded in Metamaterial Antireflection Coated Silicon

    NASA Technical Reports Server (NTRS)

    Munson, C. D.; Choi, S. K.; Coughlin, K. P.; McMahon, J. J.; Miller, K. H.; Page, L. A.; Wollack, E. J.

    2017-01-01

    Infrared (IR)-blocking filters are crucial for controlling the radiative loading on cryogenic systems and for optimizing the sensitivity of bolometric detectors in the far-IR. We present a new IR filter approach based on a combination of patterned frequency-selective structures on silicon and a thin (2575 micron thick) absorptive composite based on powdered reststrahlen absorbing materials. For a 300 K blackbody, this combination reflects approximately 50% of the incoming light and blocks greater than.99.8% of the total power with negligible thermal gradients and excellent low-frequency transmission. This allows a reduction in the IR thermal loading to negligible levels in a single cold filter. These composite filters are fabricated on silicon substrates, which provide excellent thermal transport laterally through the filter and ensure that the entire area of the absorptive filter stays near the bath temperature. A metamaterial antireflection coating cut into these substrates reduces in-band reflections to below 1%, and the in-band absorption of the powder mix is below 1% for signal bands below 750 GHz. This type of filter can be directly incorporated into silicon refractive optical elements.

  4. Thermal behavior of J-aggregates in a Langmuir-Blodgett film of pure merocyanine dye investigated by UV-visible and IR absorption spectroscopy.

    PubMed

    Hirano, Yoshiaki; Tateno, Shinsuke; Maio, Ari; Ozaki, Yukihiro

    2009-03-05

    We have characterized the structure of J-aggregate in a Langmuir-Blodgett film of pure merocyanine dye (MS18) fabricated under an aqueous subphase containing a cadmium ion (Cd2+) and have investigated its thermal behavior by UV-visible and IR absorption spectroscopy in the range from 25 to 250 degrees C with a continuous scan. The results of both UV-visible and IR absorption spectra indicate that temperature-dependent changes in the MS18 aggregation state in the pure MS18 system are closely and mildly linked with the MS18 intramolecular charge transfer and the behavior of the packing, orientation, conformation, and thermal mobility of MS18 hydrocarbon chain, respectively. The J-aggregate in the pure MS18 system dissociates from 25 to 150 degrees C, and the dissociation temperature at 150 degrees C is higher by 50 degrees C than that in the previous MS18- arachidic acid (C20) binary system. The lower dissociation temperature in the binary system originates from the fact that temperature-dependent structural disorder of cadmium arachidate (CdC20), being phase-separated from MS18, has an influence on the dissociation of J-aggregate. From 160 to 180 degrees C, thermally induced blue-shifted bands, caused by the oligomeric MS18 aggregation, appear at around 520 nm in the pure MS18 system by contraries, regardless of the lack of driving force by the melting phenomenon of CdC20. The temperature at which the 520 nm bands occur is in good agreement with the melting point (160 degrees C) of hydrocarbon chain in MS18 with Cd2+, whereas its chromophore part is clearly observed to melt near 205 degrees C by UV-visible spectra. Therefore, it is suggested that the driving force that induces the 520 nm band in the pure MS18 system arises from the partial melting of hydrocarbon chain in MS18 with Cd2+.

  5. Optical absorption and thermally stimulated depolarization current studies of nickel chloride-doped poly(vinyl alcohol) irradiated with low-level fast neutron doses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abd El-Kader, F.H.; Ibrahim, S.S.; Attia, G.

    1993-11-15

    The influence of neutron irradiation on ultraviolet/visible absorption and thermally stimulated depolarization current in nickel chloride-poly(vinyl alcohol) (PVA) cast films has been investigated. The spectral measurements indicate the responsibility of the Ni[sup 2][sup +] ion in its octahedral symmetry. Dopant concentrations higher than 10 wt % NiCl[sub 2] are found to make the samples more resistant to a degradation effect caused by neutron irradiation. The thermally stimulated depolarization currents (TSDC) of pure PVA revealed the existence of the glass transition T[sub g] and space charge relaxation peaks, whereas doped-PVA samples show a new sub-T[sub g] relaxation peak. A proposed mechanismmore » is introduced to account for the neutron effects on both glass transition and space charge relaxation peaks. The peak positions, peak currents, and stored charges of the sub-T[sub g] relaxation peak are strongly affected by both the concentration of the dopant and neutron exposure doses.« less

  6. Plasmonic characterization of photo-induced silver nanoparticles extracted from silver halide based TEM film

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

    The plasmonic responses of silver nanoparticles extracted from silver halide based electron microscope film are investigated. Photo-reduction process is carried out to convert the silver halide grains into the metallic silver. The centrifuge technique is used for separating the silver nanoparticles from the residual solution. Morphological study performed by field emission scanning electron microscope (FESEM) shows that all the nanoparticles have an average diameter of ~120 nm with a high degree of mono dispersion in size. The localized surface plasmon resonance (LSPR) absorption peak at ~537 nm confirms the presence of large size silver nanoparticles.

  7. Nanoparticle-assisted photo-Fenton reaction for photo-decomposition of humic acid

    NASA Astrophysics Data System (ADS)

    Banik, Jhuma; Basumallick, Srijita

    2017-11-01

    We report here the synthesis of CuO-doped ZnO composite nanomaterials (NMs) by chemical route and demonstrated for the first time that these NMs are efficient catalysts for H2O2-assisted photo-decomposition (photo-Fenton type catalyst) of humic acid, a natural pollutant of surface water by solar irradiation. This has been explained by faster electron transfer to OH radical at the p-n hetero-junction of this composite catalyst. Application of this composite catalyst in decomposing humus substances of local pond water by solar energy has been demonstrated.

  8. High voltage photo switch package module

    DOEpatents

    Sullivan, James S; Sanders, David M; Hawkins, Steven A; Sampayan, Stephen E

    2014-02-18

    A photo-conductive switch package module having a photo-conductive substrate or wafer with opposing electrode-interface surfaces, and at least one light-input surface. First metallic layers are formed on the electrode-interface surfaces, and one or more optical waveguides having input and output ends are bonded to the substrate so that the output end of each waveguide is bonded to a corresponding one of the light-input surfaces of the photo-conductive substrate. This forms a waveguide-substrate interface for coupling light into the photo-conductive wafer. A dielectric material such as epoxy is then used to encapsulate the photo-conductive substrate and optical waveguide so that only the metallic layers and the input end of the optical waveguide are exposed. Second metallic layers are then formed on the first metallic layers so that the waveguide-substrate interface is positioned under the second metallic layers.

  9. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  10. Polymer Electrolyte Membranes for Water Photo-Electrolysis

    PubMed Central

    Aricò, Antonino S.; Girolamo, Mariarita; Siracusano, Stefania; Sebastian, David; Baglio, Vincenzo; Schuster, Michael

    2017-01-01

    Water-fed photo-electrolysis cells equipped with perfluorosulfonic acid (Nafion® 115) and quaternary ammonium-based (Fumatech® FAA3) ion exchange membranes as separator for hydrogen and oxygen evolution reactions were investigated. Protonic or anionic ionomer dispersions were deposited on the electrodes to extend the interface with the electrolyte. The photo-anode consisted of a large band-gap Ti-oxide semiconductor. The effect of membrane characteristics on the photo-electrochemical conversion of solar energy was investigated for photo-voltage-driven electrolysis cells. Photo-electrolysis cells were also studied for operation under electrical bias-assisted mode. The pH of the membrane/ionomer had a paramount effect on the photo-electrolytic conversion. The anionic membrane showed enhanced performance compared to the Nafion®-based cell when just TiO2 anatase was used as photo-anode. This was associated with better oxygen evolution kinetics in alkaline conditions compared to acidic environment. However, oxygen evolution kinetics in acidic conditions were significantly enhanced by using a Ti sub-oxide as surface promoter in order to facilitate the adsorption of OH species as precursors of oxygen evolution. However, the same surface promoter appeared to inhibit oxygen evolution in an alkaline environment probably as a consequence of the strong adsorption of OH species on the surface under such conditions. These results show that a proper combination of photo-anode and polymer electrolyte membrane is essential to maximize photo-electrolytic conversion. PMID:28468242

  11. Polymer Electrolyte Membranes for Water Photo-Electrolysis.

    PubMed

    Aricò, Antonino S; Girolamo, Mariarita; Siracusano, Stefania; Sebastian, David; Baglio, Vincenzo; Schuster, Michael

    2017-04-29

    Water-fed photo-electrolysis cells equipped with perfluorosulfonic acid (Nafion ® 115) and quaternary ammonium-based (Fumatech ® FAA3) ion exchange membranes as separator for hydrogen and oxygen evolution reactions were investigated. Protonic or anionic ionomer dispersions were deposited on the electrodes to extend the interface with the electrolyte. The photo-anode consisted of a large band-gap Ti-oxide semiconductor. The effect of membrane characteristics on the photo-electrochemical conversion of solar energy was investigated for photo-voltage-driven electrolysis cells. Photo-electrolysis cells were also studied for operation under electrical bias-assisted mode. The pH of the membrane/ionomer had a paramount effect on the photo-electrolytic conversion. The anionic membrane showed enhanced performance compared to the Nafion ® -based cell when just TiO₂ anatase was used as photo-anode. This was associated with better oxygen evolution kinetics in alkaline conditions compared to acidic environment. However, oxygen evolution kinetics in acidic conditions were significantly enhanced by using a Ti sub-oxide as surface promoter in order to facilitate the adsorption of OH species as precursors of oxygen evolution. However, the same surface promoter appeared to inhibit oxygen evolution in an alkaline environment probably as a consequence of the strong adsorption of OH species on the surface under such conditions. These results show that a proper combination of photo-anode and polymer electrolyte membrane is essential to maximize photo-electrolytic conversion.

  12. Electromagnetic absorption properties of spacecraft and space debris

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Santoni, F.; Giusti, A.; Delfini, A.; Pastore, R.; Vricella, A.; Albano, M.; Arena, L.; Piergentili, F.; Marchetti, M.

    2017-04-01

    Aim of the work is to present a method to evaluate the electromagnetic absorption properties of spacecraft and space debris. For these objects, the radar detection ability depends mainly on volume, shape, materials type and other electromagnetic reflecting behaviour of spacecraft surface components, such as antennas or thermal blankets, and of metallic components in space debris. The higher the electromagnetic reflection coefficient of such parts, the greater the radar detection possibility. In this research an electromagnetic reverberation chamber is used to measure the absorption cross section (ACS) of four objects which may represent space structure operating components as well as examples of space debris: a small satellite, a composite antenna dish, a Thermal Protection System (TPS) tile and a carbon-based composite missile shell. The ACS mainly depends on geometrical characteristics like apertures, face numbers and bulk porosity, as well as on the type of the material itself. The ACS, which is an electromagnetic measurement, is expressed in squared meters and thus can be compared with the objects geometrical cross section. A small ACS means a quite electromagnetic reflective tendency, which is beneficial for radar observations; on the contrary, high values of ACS indicate a strong absorption of the electromagnetic field, which in turn can result a critical hindering of radar tracking.

  13. The exploitation argument against commercial surrogacy.

    PubMed

    Wilkinson, Stephen

    2003-04-01

    This paper discusses the exploitation argument against commercial surrogacy: the claim that commercial surrogacy is morally objectionable because it is exploitative. The following questions are addressed. First, what exactly does the exploitation argument amount to? Second, is commercial surrogacy in fact exploitative? Third, if it were exploitative, would this provide a sufficient reason to prohibit (or otherwise legislatively discourage) it? The focus throughout is on the exploitation of paid surrogates, although it is noted that other parties (e.g. 'commissioning parents') may also be the victims of exploitation. It is argued that there are good reasons for believing that commercial surrogacy is often exploitative. However, even if we accept this, the exploitation argument for prohibiting (or otherwise legislatively discouraging) commercial surrogacy remains quite weak. One reason for this is that prohibition may well 'backfire' and lead to potential surrogates having to do other things that are more exploitative and/or more harmful than paid surrogacy. It is concluded therefore that those who oppose exploitation should (rather than attempting to stop particular practices like commercial surrogacy) concentrate on: (a) improving the conditions under which paid surrogates 'work'; and (b) changing the background conditions (in particular, the unequal distribution of power and wealth) which generate exploitative relationships.

  14. Physical model for the photo-induced toxicity of polycyclic aromatic hydrocarbons (PAHs)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Greenburg, B.M.; Krylov, S.N.; Huang, H.D.

    1994-12-31

    A model for photo-induced toxicity of PAHs to duckweed was developed. Growth inhibition was described by photochemical reactions between PAHs and a hypothetical group of biomolecules (given the notation G) which are required for growth of the plants. Light activation of PAHs was considered in a two compartment system (water and leaves). The reaction scheme includes: photooxidation of PAHs, partitioning of PAHs into leaves, triplet formation of intact PAHs, photosensitization reactions that consume G, and reaction between photooxidized PAHs and G. The assumptions used in the model are: the rate of PAH photooxidation is slower than the rate of assimilation,more » PAH content in solution is approximately constant over the length of the toxicity test, the fluence rate of actinic radiation is lower in the leaves than in solution, the toxicity of intact PAHs with G in the absence of light is negligible, and the reaction of photooxidized PAHs with G does not require light. The authors then analyzed a series of differential equations that described toxicity. The result was an expression for growth inhibition as a function of the initial concentration of the PAH, the spectral distribution of the light source, the absorption spectrum of the PAH, the quantum yield for formation of triplet state PAH, and the rate of photo-oxidation of the PAH. The expression also includes two complex constants that can be solved by a least squares analysis of the empirical data for growth inhibition. Thus, the model allows a prediction of PAH photo-induced toxicity using only physical parameters of PAHs.« less

  15. Study on the measurement of photo-neutron for15 MV photon beam from medical linear accelerator under different irradiation geometries using passive detectors.

    PubMed

    Thekkedath, Siji Cyriac; Raman, R Ganapathi; Musthafa, M M; Bakshi, A K; Pal, Rupali; Dawn, Sandipan; Kummali, Abdul Haneefa; Huilgol, Nagraj G; Selvam, T Palani; Datta, D

    2016-01-01

    The photo-neutron dose equivalents of 15 MV Elekta precise accelerators were measured for different depths in phantom, for various field sizes, at different distances from the isocenter in the patient plane and for various wedged fields. Fast and thermal neutrons are measured using passive detectors such as Columbia Resin-39 and pair of thermoluminescent dosimetry (TLD) 600 and TLD 700 detector from Elekta medical linear accelerator. It is found that fast photo-neutron dose rate decreases as the depth increases, with a maximum of 0.57 ± 0.08 mSv/Gy photon dose at surface and minimum of 0.09 ± 0.02 mSv/Gy photon dose at 15 cm depth of water equivalent phantom with 10 cm backscatter. Photo neutrons decreases from 1.28 ± 0.03 mSv/Gy to 0.063 ± 0.032 when measured at isocenter and at 100 cm far from the field edge along the longitudinal direction in the patient plane. Fast and thermal neutron doses increases from 0.65 ± 0.05 mSv/Gy to 1.08 ± 0.07 mSv/Gy as the field size increases; from 5 cm × 5 cm to 30 cm × 30 cm for fast neutrons. With increase in wedge field angle from 0° to 60°, it is observed that the fast neutron dose increases from 0.42 ± 0.03 mSv/Gy to 0.95 ± 0.05 mSv/Gy.s Measurements indicate the photo-neutrons at few field sizes are slightly higher than the International Electrotechnical Commission standard specifications. Photo-neutrons from Omni wedged fields are studied in details. These studies of the photo-neutron energy response will enlighten the neutron dose to radiation therapy patients and are expected to further improve radiation protection guidelines.

  16. Annihilation of photochemical reactivity of photo-alignment layer.

    PubMed

    Hong, S H; Hwang, Y J; Lee, S G; Shin, D M

    2008-09-01

    The gas-polymer and liquid-polymer interfacial reactions of photosensitive polyimide can annihilate photo-reactive carbon-carbon double bonds, which remain after photo-alignment process. The annihilation processes dramatically affect voltage holding ratio and reorientation of photo-active functional groups. Photochemical dimerizations were identified using UV-visible and FT-IR spectroscopy. Polyimide films containing cinnamate groups were irradiated by linear polarized ultra violet (LPUV) light. Schadt et al. claims that the photo-alignment results from the anisotropy depletion of the cinnamate side chains as a consequence of the (2+2) cycloaddition reactions. The photo-aligned polyimide induces the orientation of nematic liquid crystals perpendicular to the polarization axis. However, the un-reacted photo-sensitive functional groups generate problems such as image sticking and reduced contrast ratio. Voltage holding ratio and photo-fading observed from photo-alignment layer can be dramatically improved by annihilation process of remnant photoreactive groups.

  17. Meningococcal Photos

    MedlinePlus

    ... Vaccine Campaign Podcast: Meningitis Immunization for Adolescents Meningitis Sepsis Meningococcal Photos Recommend on Facebook Tweet Share Compartir ... Vaccine Campaign Podcast: Meningitis Immunization for Adolescents Meningitis Sepsis File Formats Help: How do I view different ...

  18. The environmental impacts of foamed concrete production and exploitation

    NASA Astrophysics Data System (ADS)

    Namsone, E.; Korjakins, A.; Sahmenko, G.; Sinka, M.

    2017-10-01

    This paper presents a study focusing on the environmental impacts of foamed concrete production and exploitation. CO2 emissions are very important factor for describing durability and sustainability of any building material and its life cycle. The building sector is one of the largest energy-consuming sectors in the world. In this study CO2 emissions are evaluated with regard to three types of energy resources (gas, coal and eco-friendly fuel). The related savings on raw materials are up to 120 t of water per 1000 t of traditionally mixed foamed concrete and up to 350 t of sand per 1000 t of foamed concrete produced with intensive mixing technology. In addition, total reduction of CO2 emissions (up to 60 t per 1000 m3 of material) and total energy saving from introduction of foamed concrete production (depending on the type of fuel) were calculated. In order to analyze the conditions of exploitation, both thermal conductivity and thickness of wall was determined. All obtained and calculated results were compared to those of the commercially produced autoclaved aerated concrete.

  19. Photo-induced self-cleaning and sterilizing activity of Sm3+ doped ZnO nanomaterials.

    PubMed

    Saif, M; Hafez, H; Nabeel, A I

    2013-01-01

    Highly active samarium doped zinc oxide self-cleaning and biocidal surfaces (x mol% Sm(3+)/ZnO where x=0, 1, 2 and 4 mol%) with crystalline porous structures were synthesized by hydrothermal method. Sm(3+)/ZnO thin films were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopic (EDS), UV-visible diffuse reflectance and fluorescence (FL) spectroscopy. The combination between doping and hydrothermal treatments significantly altered the morphology of ZnO into rod and plate-like nanoshapes structure and enhanced its absorption and emission of ultraviolet radiation. The photo-activity in term of quantitative determination of the active oxidative species (()OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results showed that, the hydrothermally treated 2.0 mol% Sm(3+)/ZnO film (S2) is the highly active one. The optical, structural, morphology and photo-activity properties of the highly active thin film (S2) make it promising surface for self-cleaning and sterilizing applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Water metamaterial for ultra-broadband and wide-angle absorption.

    PubMed

    Xie, Jianwen; Zhu, Weiren; Rukhlenko, Ivan D; Xiao, Fajun; He, Chong; Geng, Junping; Liang, Xianling; Jin, Ronghong; Premaratne, Malin

    2018-02-19

    A subwavelength water metamaterial is proposed and analyzed for ultra-broadband perfect absorption at microwave frequencies. We experimentally demonstrate that this metamaterial shows over 90% absorption within almost the entire frequency band of 12-29.6 GHz. It is also shown that the proposed metamaterial exhibits a good thermal stability with its absorption performance almost unchanged for the temperature range from 0 to 100°C. The study of the angular tolerance of the metamaterial absorber shows its ability of working at wide angles of incidence. Given that the proposed water metamaterial absorber is low-cost and easy for manufacture, we envision it may find numerous applications in electromagnetics such as broadband scattering reduction and electromagnetic energy harvesting.

  1. Influence of thermally induced structural and morphological changes, and UV irradiation on photoluminescence and optical absorption behavior of CdS nanoparticles

    NASA Astrophysics Data System (ADS)

    Osman, M. A.; El-Said, Waleed A.; Othman, A. A.; Abd-Elrahim, A. G.

    2016-04-01

    Polycrystalline cubic CdS nanoparticles (NPs) with a crystallite size ({{D}\\text{Sch}} ) ~3 nm were synthesized by chemical precipitation method at room temperature. Thermal induced structural and morphological changes have been investigated using x-ray diffraction, high-resolution transmission electron microscope, x-ray fluorescence, Fourier transform infrared and Raman spectroscopy. The influence of these changes on optical absorption and photoluminescence (PL) characteristics have been studied. It was found that increasing annealing temperature (T a), results in structural phase transitions at 300 and 700 °C, increasing {{D}\\text{Sch}} and red shift of the optical band gap (E\\text{g}\\text{opt} ) due to the improvement in crystallinity. The photoluminescence emission spectrum of nonstoichiometric CdS (Cd-rich) nanopowder reveals emission bands at 365, 397, and 434 nm. Furthermore, PL spectrum of colloidal solution exhibits additional green and red emission bands at 535, 570 and 622 nm. To explain the mechanism of PL emission in CdS NPs, trapping and radiative recombination levels have been identified and the corresponding energy band diagrams are suggested. Annealing process results in an overall enhancement in PL intensity due to the improvement in crystallinity associated with the reduction of nonradiative surface state defects. Irradiation of CdS NPs colloidal solution at UV irradiation dose  <13 J cm-2 leads to the enhancement of PL quantum efficiency and blue shift of E\\text{g}\\text{opt} (i.e. photo-brightening) due to the decrease in the particle size deduced from Brus equation ≤ft({{D}\\text{Brus}}\\right) , This behavior is due to UV irradiation effects such as photopolymerization, the formation of CdSO4 passivation layers due to photooxidation and the reduction in {{D}\\text{Brus}} by photocorrosion process. At UV irradiation dose  <13 J cm-2, PL emission intensity continuously enhances without any change in both E

  2. Two questions about surrogacy and exploitation.

    PubMed

    Wertheimer, Alan

    1992-01-01

    In this article I will consider two related questions about surrogacy and exploitation: (1) Is surrogacy exploitative? (2) If surrogacy is exploitative, what is the moral force of this exploitation? Briefly stated, I shall argue that whether surrogacy is exploitative depends on whether exploitation must be harmful to the exploited party or whether (as I think) there can be mutually advantageous exploitation. It also depends on some facts about surrogacy about which we have little reliable evidence and on our philosophical view on what counts as a harm to the surrogate. Our answer to the second question will turn in part on the account of exploitation we invoke in answering the first question and in part on the way in which we resolve some other questions about the justification of state interference. I shall suggest, however, that if surrogacy is a form of voluntary and mutually advantageous exploitation, then there is a strong presumption that surrogacy contracts should be permitted and even enforceable, although that presumption may be overridden on other grounds.

  3. Broadband photocarrier dynamics and nonlinear absorption of PLD-grown WTe2 semimetal films

    NASA Astrophysics Data System (ADS)

    Gao, Wenbin; Huang, Lei; Xu, Jinlong; Chen, Yequan; Zhu, Chunhui; Nie, Zhonghui; Li, Yao; Wang, Xuefeng; Xie, Zhenda; Zhu, Shining; Xu, Jun; Wan, Xiangang; Zhang, Chao; Xu, Yongbing; Shi, Yi; Wang, Fengqiu

    2018-04-01

    WTe2 is a unique material in the family of transition metal dichalcogenides and it has been proposed as a candidate for type-II Weyl semimetals. However, thus far, studies on the optical properties of this emerging material have been significantly hindered by the lack of large-area, high-quality WTe2 materials. Here, we grow a centimeter-scale, highly crystalline WTe2 ultrathin film (˜35 nm) by a pulsed laser deposition technique. Broadband pump-probe spectroscopy (1.2-2.5 μm) reveals a peculiar ultrafast optical response where an initial photo-bleaching signal (lasting ˜3 ps) is followed by a long-lived photoinduced absorption signature. Nonlinear absorption characterization using femtosecond pulses confirms the saturable absorption response of the WTe2 ultrathin films, and we further demonstrated a mode-locked Thulium fiber laser using a WTe2 absorber. Our work provides important insights into linear and nonlinear optical responses of WTe2 thin films.

  4. Slotting Fins of Heat Exchangers to Provide Thermal Breaks

    NASA Technical Reports Server (NTRS)

    Scull, Timothy D.

    2003-01-01

    Heat exchangers that include slotted fins (in contradistinction to continuous fins) have been invented. The slotting of the fins provides thermal breaks that reduce thermal conduction along flow paths (longitudinal thermal conduction), which reduces heat-transfer efficiency. By increasing the ratio between transverse thermal conduction (the desired heat-transfer conduction) and longitudinal thermal conduction, slotting of the fins can be exploited to (1) increase heat-transfer efficiency (thereby reducing operating cost) for a given heat-exchanger length or to (2) reduce the length (thereby reducing the weight and/or cost) of the heat exchanger needed to obtain a given heat transfer efficiency. By reducing the length of a heat exchanger, one can reduce the pressure drop associated with the flow through it. In a case in which slotting enables the use of fins with thermal conductivity greater than could otherwise be tolerated on the basis of longitudinal thermal conduction, one can exploit the conductivity to make the fins longer (in the transverse direction) than they otherwise could be, thereby making it possible to make a heat exchanger that contains fewer channels and therefore, that weighs less, contains fewer potential leak paths, and can be constructed from fewer parts and, hence, reduced cost.

  5. Photo-Acoustic Spectroscopy Reveals Extrinsic Optical Chirality in GaAs-Based Nanowires Partially Covered with Gold

    NASA Astrophysics Data System (ADS)

    Petronijevic, E.; Leahu, G.; Belardini, A.; Centini, M.; Li Voti, R.; Hakkarainen, T.; Koivusalo, E.; Rizzo Piton, M.; Suomalainen, S.; Guina, M.; Sibilia, C.

    2018-04-01

    We report on the extrinsic chirality behavior of GaAs-based NWs asymmetrically hybridized with Au. The samples are fabricated by a recently developed, lithography-free self-organized GaAs growth, with the addition of AlGaAs shell and GaAs supershell. The angled Au flux is then used to cover three-out-of-six sidewalls with a thin layer of Au. Oblique incidence and proper sample orientation can lead to circular dichroism. We characterize this chiral behavior at 532 {nm} and 980 {nm} by means of photo-acoustic spectroscopy, which directly measures the difference in absorption for the circularly polarized light of the opposite headedness. For the first time to our knowledge, circular dichroism is observed in both the amplitude and the phase of the photo-acoustic signal. We strongly believe that such samples can be used for chiral applications, spanning from circularly polarized light emission, to the enantioselectivity applications.

  6. Broadband infrared imaging spectroscopy for standoff detection of trace explosives

    NASA Astrophysics Data System (ADS)

    Kendziora, Christopher A.; Furstenberg, Robert; Papantonakis, Michael; Nguyen, Viet; McGill, R. Andrew

    2016-05-01

    This manuscript describes advancements toward a mobile platform for standoff detection of trace explosives on relevant substrates using broadband infrared spectroscopic imaging. In conjunction with this, we are developing a technology for detection based on photo-thermal infrared (IR) imaging spectroscopy (PT-IRIS). PT-IRIS leverages one or more IR quantum cascade lasers (QCL), tuned to strong absorption bands in the analytes and directed to illuminate an area on a surface of interest. An IR focal plane array is used to image the surface thermal emission upon laser illumination. The PT-IRIS signal is processed as a hyperspectral image cube comprised of spatial, spectral and temporal dimensions as vectors within a detection algorithm. Here we describe methods to increase both sensitivity to trace explosives and selectivity between different analyte types by exploiting a broader spectral range than in previous configurations. Previously we demonstrated PT-IRIS at several meters of standoff distance indoors and in field tests, while operating the lasers below the infrared eye-safe intensity limit (100 mW/cm2). Sensitivity to explosive traces as small as a single 10 μm diameter particle (~1 ng) has been demonstrated.

  7. Influence of Nitrogen Doping on Device Operation for TiO2-Based Solid-State Dye-Sensitized Solar Cells: Photo-Physics from Materials to Devices

    PubMed Central

    Wang, Jin; Tapio, Kosti; Habert, Aurélie; Sorgues, Sebastien; Colbeau-Justin, Christophe; Ratier, Bernard; Scarisoreanu, Monica; Toppari, Jussi; Herlin-Boime, Nathalie; Bouclé, Johann

    2016-01-01

    Solid-state dye-sensitized solar cells (ssDSSC) constitute a major approach to photovoltaic energy conversion with efficiencies over 8% reported thanks to the rational design of efficient porous metal oxide electrodes, organic chromophores, and hole transporters. Among the various strategies used to push the performance ahead, doping of the nanocrystalline titanium dioxide (TiO2) electrode is regularly proposed to extend the photo-activity of the materials into the visible range. However, although various beneficial effects for device performance have been observed in the literature, they remain strongly dependent on the method used for the production of the metal oxide, and the influence of nitrogen atoms on charge kinetics remains unclear. To shed light on this open question, we synthesized a set of N-doped TiO2 nanopowders with various nitrogen contents, and exploited them for the fabrication of ssDSSC. Particularly, we carefully analyzed the localization of the dopants using X-ray photo-electron spectroscopy (XPS) and monitored their influence on the photo-induced charge kinetics probed both at the material and device levels. We demonstrate a strong correlation between the kinetics of photo-induced charge carriers probed both at the level of the nanopowders and at the level of working solar cells, illustrating a direct transposition of the photo-physic properties from materials to devices. PMID:28344292

  8. Enhanced Absorption in 2D Materials Via Fano- Resonant Photonic Crystals

    DOE PAGES

    Wang, Wenyi; Klotz, Andrey; Yang, Yuanmu; ...

    2015-05-01

    The use of two-dimensional (2D) materials in optoelectronics has attracted much attention due to their fascinating optical and electrical properties. For instance, graphenebased devices have been employed for applications such as ultrafast and broadband photodetectors and modulators while transition metal dichalcogenide (TMDC) based photodetectors can be used for ultrasensitive photodetection. However, the low optical absorption of 2D materials arising from their atomic thickness limits the maximum attainable external quantum efficiency. For example, in the visible and NIR regimes monolayer MoS 2 and graphene absorb only ~10% and 2.3% of incoming light, respectively. Here, we experimentally demonstrate the use of Fano-resonantmore » photonic crystals to significantly boost absorption in atomically thin materials. Using graphene as a test bed, we demonstrate that absorption in the monolayer thick material can be enhanced to 77% within the telecommunications band, the highest value reported to date. We also show that the absorption in the Fano-resonant structure is non-local, with light propagating up to 16 μm within the structure. This property is particularly beneficial in harvesting light from large areas in field-effect-transistor based graphene photodetectors in which separation of photo-generated carriers only occurs ~0.2 μm adjacent to the graphene/electrode interface.« less

  9. Examination of coagulant additives on qualitative composition of selected thermal waters

    NASA Astrophysics Data System (ADS)

    Łukasiewicz, Ewelina; Rząsa, Mariusz

    2017-10-01

    On the territory of Poland occur rich deposits of thermal waters. Although the utilisation of these waters is continuously extending, Poland is not exploiting their full geothermal potential due to high investment costs. Thermal waters industry in Poland to date indicates operations within mainly balneology as well as recreation objectives. Higher temperature values of these waters foster a washout in the surrounding rocks resulting in a high concentration of diluted substances which must be often removed. The following study investigates thermal waters from three intakes for which coagulation processes were conducted. Research clearly shows that coagulant additives not impact on the qualitative composition of thermal water, what is very important according to medicinal properties of water. The study results may be further applied as a valuable piece of information for further exploitation in balneology or within the heating sector and other installations.

  10. Oxygen optical gas sensing by reversible fluorescence quenching in photo-oxidized poly(9,9-dioctylfluorene) thin films.

    PubMed

    Anni, M; Rella, R

    2010-02-04

    We investigated the fluorescence (FL) dependence on the environment oxygen content of poly(9,9-dioctylfluorene) (PF8) thin films. We show that the PF8 interactions with oxygen are not limited to the known irreversible photo-oxidation, resulting in the formation of Keto defects, but also reversible FL quenching is observed. This effect, which is stronger for the Keto defects than for the PF8, has been exploited for the realization of a prototype oxygen sensor based on FL quenching. The sensing sensitivity of Keto defects is comparable with the state of the art organic oxygen sensors based on phosphorescence quenching.

  11. Redesigning photo-ID to improve unfamiliar face matching performance.

    PubMed

    White, David; Burton, A Mike; Jenkins, Rob; Kemp, Richard I

    2014-06-01

    Viewers find it difficult to match photos of unfamiliar faces for identity. Despite this, the use of photographic ID is widespread. In this study we ask whether it is possible to improve face matching performance by replacing single photographs on ID documents with multiple photos or an average image of the bearer. In 3 experiments we compare photo-to-photo matching with photo-to-average matching (where the average is formed from multiple photos of the same person) and photo-to-array matching (where the array comprises separate photos of the same person). We consistently find an accuracy advantage for average images and photo arrays over single photos, and show that this improvement is driven by performance in match trials. In the final experiment, we find a benefit of 4-image arrays relative to average images for unfamiliar faces, but not for familiar faces. We propose that conventional photo-ID format can be improved, and discuss this finding in the context of face recognition more generally. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  12. Simulation study of the thermal and the thermoelastic effects induced by pulsed laser absorption in human skin

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Young; Jang, Kyungmin; Yang, Seung-Jin; Baek, Jun-Hyeok; Park, Jong-Rak; Yeom, Dong-Il; Kim, Ji-Sun; Kim, Hyung-Sik; Jun, Jae-Hoon; Chung, Soon-Cheol

    2016-04-01

    We studied the thermal and the mechanical effects induced by pulsed laser absorption in human skin by numerically solving the heat-transfer and the thermoelastic wave equations. The simulation of the heat-transfer equation yielded the spatiotemporal distribution of the temperature increase in the skin, which was then used in the driving term of the thermoelastic wave equation. We compared our simulation results for the temperature increase and the skin displacements with the measured and numerical results, respectively. For the comparison, we used a recent report by Jun et al. [Sci. Rep. 5, 11016 (2015)], who measured in vivo skin temperature and performed numerical simulation of the thermoelastic wave equation using a simple assumption about the temporal evolution of the temperature distribution, and found their results to be in good agreement with our results. In addition, we obtained solutions for the stresses in the human skin and analyzed their dynamic behaviors in detail.

  13. Absorption properties of alternative chromophores for use in laser tissue soldering applications.

    PubMed

    Byrd, Brian D; Heintzelman, Douglas L; McNally-Heintzelman, Karen M

    2003-01-01

    The feasibility of using alternative chromophores in laser tissue soldering applications was explored. Two commonly used chromophores, indocyanine green (ICG), and methylene blue (MB) were investigated, as well as three different food colorings: red #40 (RFC), blue #1 (BFC), and green consisting of yellow #5 and blue #1 (GFC). Three experimental studies were conducted: (i) The absorption profiles of the five chromophores, when diluted in deionized water and when bound to protein, were recorded; (ii) the effect of accumulated thermal dosages on the absorption profile of the chromophores was evaluated; and (iii) the stability of the absorption profiles of the chromophore-doped solutions when exposed to ambient light for extended time periods was measured. The peak absorption wavelengths of ICG, MB, RFC, and BFC, were found to be 805 nm, 665 nm, 503 nm, and 630 nm respectively in protein solder. The GFC had two absorption peaks at 426 nm and 630 nm, corresponding to the two dye components comprising this color. The peak absorption wavelength of ICG and MB was dependent on the choice of solvent (deionized water or protein). In contrast, the peak absorption wavelengths of the three chromophores were not dependent on the choice of solvent. ICG and MB showed a significant decrease in absorbance units with increased time and temperature when heated to temperature up to 100 degrees C. A significant decrease in the absorption peak occurred in the ICG and MB samples when exposed to ambient light for a period of 7 days. Negligible change in absorption with accumulated thermal dose up to 100 degrees C or light dose (over a period of 84 days) was observed for any of the three food colorings investigated.

  14. One-pot synthesis of dextran decorated reduced graphene oxide nanoparticles for targeted photo-chemotherapy.

    PubMed

    Hu, Yanfang; He, Liang; Ding, Jianxun; Sun, Diankui; Chen, Li; Chen, Xuesi

    2016-06-25

    Graphene-based nanocarriers show great potential in photo-chemotherapy, however, to prepare desired reduced graphene oxide (rGO) nanoparticles in a facile way is still a challenge. Herein, a novel strategy has been presented to prepare rGO nanoparticle using dextran (Dex) as a reducing agent. In this strategy, Dex was directly conjugated on rGO by hydrogen bond and then self-assemble to form rGO/Dex nanoparticles. After decorated by dextran, rGO-based nanoparticles not only show excellent biocompatibility but also can load anticancer drug for photo-chemotherapy. The data of fourier transform infrared (FT-IR) analysis, Raman spectrum analysis, thermos-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), the transmission electron microscope (TEM) image and dynamic light scattering (DLS) measurements powerfully proved that the stable rGO-based nanoparticles with desired nanosize have been successfully prepared. To verify the photo-chemotherapy, anticancer drug, doxorubicin (DOX), has been loaded on rGO/Dex nanoparticles (rGO/DOX/Dex). And RGD, a kind of oligopeptide which can improve the intracellular uptake by αvβ3 recognition, also has been introduced (rGO/DOX/RDex). Compared with single chemotherapy, rGO/DOX/Dex and rGO/DOX/RDex combining the local specific chemotherapy and external near-infrared (NIR) photo-thermal therapy show higher therapeutic efficacy, endowing the desired rGO-based nanoparticle with great potential for cancer treatments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Apparatus and method for transient thermal infrared spectrometry

    DOEpatents

    McClelland, John F.; Jones, Roger W.

    1991-12-03

    A method and apparatus for enabling analysis of a material (16, 42) by applying a cooling medium (20, 54) to cool a thin surface layer portion of the material and to transiently generate a temperature differential between the thin surface layer portion and the lower portion of the material sufficient to alter the thermal infrared emission spectrum of the material from the black-body thermal infrared emission spectrum of the material. The altered thermal infrared emission spectrum of the material is detected by a spectrometer/detector (28, 50) while the altered thermal infrared emission spectrum is sufficiently free of self-absorption by the material of the emitted infrared radiation. The detection is effected prior to the temperature differential propagating into the lower portion of the material to an extent such that the altered thermal infrared emission spectrum is no longer sufficiently free of self-absorption by the material of emitted infrared radiation, so that the detected altered thermal infrared emission spectrum is indicative of the characteristics relating to the molecular composition of the material.

  16. Automatic digital photo-book making system

    NASA Astrophysics Data System (ADS)

    Wang, Wiley; Teo, Patrick; Muzzolini, Russ

    2010-02-01

    The diversity of photo products has grown more than ever before. A group of photos are not only printed individually, but also can be arranged in specific order to tell a story, such as in a photo book, a calendar or a poster collage. Similar to making a traditional scrapbook, digital photo book tools allow the user to choose a book style/theme, layouts of pages, backgrounds and the way the pictures are arranged. This process is often time consuming to users, given the number of images and the choices of layout/background combinations. In this paper, we developed a system to automatically generate photo books with only a few initial selections required. The system utilizes time stamps, color indices, orientations and other image properties to best fit pictures into a final photo book. The common way of telling a story is to lay the pictures out in chronological order. If the pictures are proximate in time, they will coincide with each other and are often logically related. The pictures are naturally clustered along a time line. Breaks between clusters can be used as a guide to separate pages or spreads, thus, pictures that are logically related can stay close on the same page or spread. When people are making a photo book, it is helpful to start with chronologically grouped images, but time alone wont be enough to complete the process. Each page is limited by the number of layouts available. Many aesthetic rules also apply, such as, emphasis of preferred pictures, consistency of local image density throughout the whole book, matching a background to the content of the images, and the variety of adjacent page layouts. We developed an algorithm to group images onto pages under the constraints of aesthetic rules. We also apply content analysis based on the color and blurriness of each picture, to match backgrounds and to adjust page layouts. Some of our aesthetic rules are fixed and given by designers. Other aesthetic rules are statistic models trained by using

  17. ‘Squeezing’ near-field thermal emission for ultra-efficient high-power thermophotovoltaic conversion

    PubMed Central

    Karalis, Aristeidis; Joannopoulos, J. D.

    2016-01-01

    We numerically demonstrate near-field planar ThermoPhotoVoltaic systems with very high efficiency and output power, at large vacuum gaps. Example performances include: at 1200 °K emitter temperature, output power density 2 W/cm2 with ~47% efficiency at 300 nm vacuum gap; at 2100 °K, 24 W/cm2 with ~57% efficiency at 200 nm gap; and, at 3000 °K, 115 W/cm2 with ~61% efficiency at 140 nm gap. Key to this striking performance is a novel photonic design forcing the emitter and cell single modes to cros resonantly couple and impedance-match just above the semiconductor bandgap, creating there a ‘squeezed’ narrowband near-field emission spectrum. Specifically, we employ surface-plasmon-polariton thermal emitters and silver-backed semiconductor-thin-film photovoltaic cells. The emitter planar plasmonic nature allows for high-power and stable high-temperature operation. Our simulations include modeling of free-carrier absorption in both cell electrodes and temperature dependence of the emitter properties. At high temperatures, the efficiency enhancement via resonant mode cross-coupling and matching can be extended to even higher power, by appropriately patterning the silver back electrode to enforce also an absorber effective surface-plasmon-polariton mode. Our proposed designs can therefore lead the way for mass-producible and low-cost ThermoPhotoVoltaic micro-generators and solar cells. PMID:27363522

  18. Flexible composite material with phase change thermal storage

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    2001-01-01

    A highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The composite material can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The composite may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the PCM composite also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, ,gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  19. Flexible composite material with phase change thermal storage

    NASA Technical Reports Server (NTRS)

    Buckley, Theresa M. (Inventor)

    1999-01-01

    A highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The composite material can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The composite may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the PCM composite also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  20. Ultraviolet absorption cross-sections of hot carbon dioxide

    NASA Astrophysics Data System (ADS)

    Oehlschlaeger, Matthew A.; Davidson, David F.; Jeffries, Jay B.; Hanson, Ronald K.

    2004-12-01

    The temperature-dependent ultraviolet absorption cross-section for CO 2 has been measured in shock-heated gases between 1500 and 4500 K at 216.5, 244, 266, and 306 nm. Continuous-wave lasers provide the spectral brightness to enable precise time-resolved measurements with the microsecond time-response needed to monitor thermal decomposition of CO 2 at temperatures above 3000 K. The photophysics of the highly temperature dependent cross-section is discussed. The new data allows the extension of CO 2 absorption-based temperature sensing methods to higher temperatures, such as those found in behind detonation waves.

  1. Airborne interferometer for atmospheric emission and solar absorption.

    PubMed

    Keith, D W; Dykema, J A; Hu, H; Lapson, L; Anderson, J G

    2001-10-20

    The interferometer for emission and solar absorption (INTESA) is an infrared spectrometer designed to study radiative transfer in the troposphere and lower stratosphere from a NASA ER-2 aircraft. The Fourier-transform spectrometer (FTS) operates from 0.7 to 50 mum with a resolution of 0.7 cm(-1). The FTS observes atmospheric thermal emission from multiple angles above and below the aircraft. A heliostat permits measurement of solar absorption spectra. INTESA's calibration system includes three blackbodies to permit in-flight assessment of radiometric error. Results suggest that the in-flight radiometric accuracy is ~0.5 K in the mid-infrared.

  2. A library of georeferenced photos from the field

    NASA Astrophysics Data System (ADS)

    Xiao, Xiangming; Dorovskoy, Pavel; Biradar, Chandrashekhar; Bridge, Eli

    2011-12-01

    A picture is worth a thousand of words, and every day hundreds of scientists, students, and environmentally aware citizens are taking field photos to document their observations of rocks, glaciers, soils, forests, wetlands, croplands, rangelands, livestock, and birds and mammals, as well as important events such as droughts, floods, wildfires, insect emergences, and infectious disease outbreaks. Where are those field photos stored? Can they be shared in a timely fashion to support education, research, and the leisure activities of citizens across the world? What are the financial and intellectual costs if those field photos are lost or not shared? Recently, researchers at the University of Oklahoma developed and released the Global Geo-Referenced Field Photo Library (hereinafter referred to as the Field Photo Library; http://www.eomf.ou.edu/photos/), a Web-based data portal designed for researchers and educators who wish to archive and share field photos from across the world, each tagged with exact positioning data (Figure 1). The data portal has a simple user interface that allows people to upload, query, and download georeferenced field photos in the library.

  3. Polarization-controlled optimal scatter suppression in transient absorption spectroscopy

    PubMed Central

    Malý, Pavel; Ravensbergen, Janneke; Kennis, John T. M.; van Grondelle, Rienk; Croce, Roberta; Mančal, Tomáš; van Oort, Bart

    2017-01-01

    Ultrafast transient absorption spectroscopy is a powerful technique to study fast photo-induced processes, such as electron, proton and energy transfer, isomerization and molecular dynamics, in a diverse range of samples, including solid state materials and proteins. Many such experiments suffer from signal distortion by scattered excitation light, in particular close to the excitation (pump) frequency. Scattered light can be effectively suppressed by a polarizer oriented perpendicular to the excitation polarization and positioned behind the sample in the optical path of the probe beam. However, this introduces anisotropic polarization contributions into the recorded signal. We present an approach based on setting specific polarizations of the pump and probe pulses, combined with a polarizer behind the sample. Together, this controls the signal-to-scatter ratio (SSR), while maintaining isotropic signal. We present SSR for the full range of polarizations and analytically derive the optimal configuration at angles of 40.5° between probe and pump and of 66.9° between polarizer and pump polarizations. This improves SSR by (or compared to polarizer parallel to probe). The calculations are validated by transient absorption experiments on the common fluorescent dye Rhodamine B. This approach provides a simple method to considerably improve the SSR in transient absorption spectroscopy. PMID:28262765

  4. Integrated photovoltaic-thermal solar energy conversion systems

    NASA Technical Reports Server (NTRS)

    Samara, G. A.

    1975-01-01

    A combined photovoltaic/thermal collector has been built and is now being tested. Initial tests have concentrated on evaluating the thermal efficiency of the collector before and after the silicon cells are mounted. With likely improvements in bonding between cells and receiver and in the absorptivity of the cells, thermal efficiencies greater than 50% can be expected for the combined receiver operating at 100 C.

  5. Absorption coefficients for water vapor at 193 nm from 300 to 1073 K

    NASA Technical Reports Server (NTRS)

    Kessler, W. J.; Carleton, K. L.; Marinelli, W. J.

    1993-01-01

    Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are compared to room temperature and high temperature shock tube measurements with good agreement. The absorption can be parameterized by a nu3 vibrational mode reaction coordinate and the thermal population of the nu3 mode.

  6. Sequential dark and photo fermentation hydrogen production from hydrolyzed corn stover: A pilot test using 11 m3 reactor.

    PubMed

    Zhang, Quanguo; Zhang, Zhiping; Wang, Yi; Lee, Duu-Jong; Li, Gang; Zhou, Xuehua; Jiang, Danping; Xu, Bo; Lu, Chaoyang; Li, Yameng; Ge, Xumeng

    2018-04-01

    Pilot tests of sequential dark and photo fermentation H 2 production were for the first time conducted in a 11 m 3 reactor (3 m 3 for dark and 8 m 3 for photo compartments). A combined solar and light-emitting diode illumination system and a thermal controlling system was installed and tested. With dark fermentation unit maintained at pH 4.5 and 35 °C and photo fermentation unit at pH 7.0 and 30 °C, the overall biogas production rate using hydrolyzed corn stover as substrate reached 87.8 ± 3.8 m 3 /d with 68% H 2 content, contributed by dark unit at 7.5 m 3 -H 2 /m 3 -d and by photo unit at 4.7 m 3 /m 3 -d. Large variation was noted for H 2 production rate in different compartments of the tested units, revealing the adverse effects of poor mixing, washout, and other inhomogeneity associated with large reactor operations. Copyright © 2018 Elsevier Ltd. All rights reserved.

  7. Single nanowire thermal conductivity measurements by Raman thermography.

    PubMed

    Doerk, Gregory S; Carraro, Carlo; Maboudian, Roya

    2010-08-24

    A facile, rapid, and nondestructive technique for determining the thermal conductivity of individual nanowires based on Raman temperature mapping has been demonstrated. Using calculated absorption efficiencies, the thermal conductivities of single cantilevered Si nanowires grown by the vapor-liquid-solid method are measured and the results agree well with values predicted by diffuse phonon boundary scattering. As a measurement performed on the wire, thermal contact effects are avoided and ambient air convection is found to be negligible for the range of diameters measured. The method's versatility is further exemplified in the reverse measurement of a single nanowire absorption efficiency assuming diffuse phonon boundary scattering. The results presented here outline the broad utility that Raman thermography may have for future thermoelectric and photovoltaic characterization of nanostructures.

  8. DNA Microcapsule for Photo-Triggered Drug Release Systems.

    PubMed

    Kamiya, Yukiko; Yamada, Yoshinobu; Muro, Takahiro; Matsuura, Kazunori; Asanuma, Hiroyuki

    2017-12-19

    In this study we constructed spherical photo-responsive microcapsules composed of three photo-switchable DNA strands. These strands first formed a three-way junction (TWJ) motif that further self-assembled to form microspheres through hybridization of the sticky-end regions of each branch. To serve as the photo-switch, multiple unmodified azobenzene (Azo) or 2,6-dimethyl-4-(methylthio)azobenzene (SDM-Azo) were introduced into the sticky-end regions via a d-threoninol linker. The DNA capsule structure deformed upon trans-to-cis isomerization of Azo or SDM-Azo induced by specific light irradiation. In addition, photo-triggered release of encapsulated small molecules from the DNA microcapsule was successfully achieved. Moreover, we demonstrated that photo-triggered release of doxorubicin caused cytotoxicity to cultured cells. This biocompatible photo-responsive microcapsule has potential application as a photo-controlled drug-release system. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Using Photo CDs for Instruction.

    ERIC Educational Resources Information Center

    Yeamans, George T.

    1994-01-01

    Describes the use of Kodak's Photo CD for teaching, testing, and practicing basic concepts of photography and composition based on experiences at Ball State University, Muncie, Indiana. The use of practice disks is explained, learning outcomes and student attitudes are discussed, and a sidebar describes new software for use with Photo CDs. (LRW)

  10. Searching for Variability of NV Intrinsic Narrow Absorption Line Systems

    NASA Astrophysics Data System (ADS)

    Rodruck, Michael; Charlton, Jane; Ganguly, Rajib

    2018-01-01

    The majority of quasar absorption line systems with NV detected are found within the associated region (within 5000 km/s of the quasar redshift) and many/most are believed to be related to the quasar accretion disk wind or outflows. The most definite evidence that these NV absorbers are "intrinsic" is partial covering of the quasar continuum source and/or broad line region. Over 75 quasars containing NV narrow absorption lines have observations obtained at different times with the Keck/HIRES and the VLT/UVES spectrographs at high resolution. The interval between these observations range from months to a decade in the quasar rest frame. While variability is common for intrinsic broad and mini-broad absorption lines, intrinsic narrow absorption lines have been found to be less likely to vary, though systematic studies with large, high quality datasets have been limited. The variability timescales are useful for deriving gas densities and thus the distances from the central engines. This is important in mapping the quasar surroundings, understanding the accretion disk wind mechanism, and assessing the effect the wind has on the galaxy surroundings. We report on the results of a systematic study of variability of NV NALs, exploiting the overlap of targets for observations in the archives of Keck and VLT, and discuss the consequences for interpretation of the origin of intrinsic narrow absorption lines.

  11. Absorption and emission properties of photonic crystals and metamaterials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Peng, Lili

    We study the emission and absorption properties of photonic crystals and metamaterials using Comsol Multiphysics and Ansoft HFSS as simulation tools. We calculate the emission properties of metallic designs using drude model and the results illustrate that an appropriate termination of the surface of the metallic structure can significantly increase the absorption and therefore the thermal emissivity. We investigate the spontaneous emission rate modifications that occur for emitters inside two-dimensional photonic crystals and find the isotropic and directional emissions with respect to different frequencies as we have expected.

  12. A simple heat-pipe cell for X-ray absorption spectrometry of potassium vapor

    NASA Astrophysics Data System (ADS)

    Pres̆eren, R.; Kodre, A.; Arc̆on, I.; Padez̆nik Gomils̆ek, J.; Hribar, M.

    1999-01-01

    The construction and operation of a simple high-temperature X-ray absorption cell for potassium vapor is described. The principle of "spectroscopic heat pipe" is exploited to separate kapton windows, indispensable for good transmission in the low-energy region, from the hot and aggressive vapor. High-resolution spectrum of the K-edge region of atomic potassium reveals fingerprints of multielectron photoexcitations.

  13. Influence of light absorption on relativistic self-focusing of Gaussian laser beam in cold quantum plasma

    NASA Astrophysics Data System (ADS)

    Patil, S. D.; Valkunde, A. T.; Vhanmore, B. D.; Urunkar, T. U.; Gavade, K. M.; Takale, M. V.

    2018-05-01

    When inter particle distance is comparable to the de Broglies wavelength of charged particles, quantum effects in plasmas are unavoidable. We have exploited an influence of light absorption on self-focusing of Gaussian laser beam in cold quantum plasma by considering relativistic nonlinearity. Nonlinear differential equation governing beam-width parameter has been established by using parabolic equation approach under paraxial and WKB approximations. The effect of light absorption on variation of beam-width parameter with dimensionless distance of propagation is presented graphically and discussed. It is found that light absorption plays vital role in weakening the relativistic self-focusing of laser beam during propagation in cold quantum plasma and gives reasonably interesting results.

  14. Radiative and Thermal Impacts of Smoke Aerosol Longwave Absorption during Fires in the Moscow Region in Summer 2010

    NASA Astrophysics Data System (ADS)

    Gorchakova, I. A.; Mokhov, I. I.; Anikin, P. P.; Emilenko, A. S.

    2018-03-01

    The aerosol longwave radiative forcing of the atmosphere and heating rate of the near-surface aerosol layer are estimated for the extreme smoke conditions in the Moscow region in summer 2010. Thermal radiation fluxes in the atmosphere are determined using the integral transmission function and semiempirical aerosol model developed on the basis of standard aerosol models and measurements at the Zvenigorod Scientific Station, Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences. The aerosol radiative forcing reached 33 W/m2 at the lower atmospheric boundary and ranged between-1.0 and 1.0 W/m2 at the upper atmospheric boundary. The heating rate of the 10-m atmospheric layer near surface was up to 0.2 K/h during the maximum smoke conditions on August 7-9. The sensitivity of the aerosol longwave radiative forcing to the changes in the aerosol absorption coefficient and aerosol optical thickness are estimated.

  15. All new custom path photo book creation

    NASA Astrophysics Data System (ADS)

    Wang, Wiley; Muzzolini, Russ

    2012-03-01

    In this paper, we present an all new custom path to allow consumers to have full control to their photos and the format of their books, while providing them with guidance to make their creation fast and easy. The users can choose to fully automate the initial creation, and then customize every page. The system manage many design themes along with numerous design elements, such as layouts, backgrounds, embellishments and pattern bands. The users can also utilize photos from multiple sources including their computers, Shutterfly accounts, Shutterfly Share sites and Facebook. The users can also use a photo as background, add, move and resize photos and text - putting what they want where they want instead of being confined to templates. The new path allows users to add embellishments anywhere in the book, and the high-performance platform can support up to 1,000 photos per book and up to 25 pictures per page. The path offers either Smart Autofill or Storyboard features allowing customers to populate their books with photos so they can add captions and customize the pages.

  16. Evaluation of hydrogen absorption cells for observations of the planetary coronas

    NASA Astrophysics Data System (ADS)

    Kuwabara, M.; Taguchi, M.; Yoshioka, K.; Ishida, T.; de Oliveira, N.; Ito, K.; Kameda, S.; Suzuki, F.; Yoshikawa, I.

    2018-02-01

    Newly designed Lyman-alpha absorption cells for imaging hydrogen planetary corona were characterized using an ultra high resolution Fourier transform spectrometer installed on the DESIRS (Dichroïsme Et Spectroscopie par Interaction avec le Rayonnement Synchrotron) beamline of Synchrotron SOLEIL in France. The early absorption cell installed in the Japanese Mars orbiter NOZOMI launched in 1998 had not been sufficiently optimized due to its short development time. The new absorption cells are equipped with the ability to change various parameters, such as filament shape, applied power, H2 gas pressure, and geometrical configuration. We found that the optical thickness of the new absorption cell was ˜4 times higher than the earlier one at the center wavelength of Lyman-alpha absorption, by optimizing the condition to promote thermal dissociation of H2 molecules into two H atoms on a hot tungsten filament. The Doppler temperature of planetary coronas could be determined with an accuracy better than 100 K with the performance of the newly developed absorption cell.

  17. CNT based thermal Brownian motor to pump water in nanodevices

    NASA Astrophysics Data System (ADS)

    Oyarzua, Elton; Zambrano, Harvey; Walther, J. H.

    2016-11-01

    Brownian molecular motors are nanoscale machines that exploit thermal fluctuations for directional motion by employing mechanisms such as the Feynman-Smoluchowski ratchet. In this study, using Non Equilibrium Molecular Dynamics, we propose a novel thermal Brownian motor for pumping water through Carbon Nanotubes (CNTs). To achieve this we impose a thermal gradient along the axis of a CNT filled with water and impose, in addition, a spatial asymmetry by fixing specific zones on the CNT in order to modify the vibrational modes of the CNT. We find that the temperature gradient and imposed spatial asymmetry drive the water flow in a preferential direction. We systematically modified the magnitude of the applied thermal gradient and the axial position of the fixed points. The analysis involves measurement of the vibrational modes in the CNTs using a Fast Fourier Transform (FFT) algorithm. We observed water flow in CNTs of 0.94, 1.4 and 2.0 nm in diameter, reaching a maximum velocity of 5 m/s for a thermal gradient of 3.3 K/nm. The proposed thermal motor is capable of delivering a continuous flow throughout a CNT, providing a useful tool for driving liquids in nanofluidic devices by exploiting thermal gradients. We aknowledge partial support from Fondecyt project 11130559.

  18. Manipulation of enhanced absorption with tilted hexagonal boron nitride slabs

    NASA Astrophysics Data System (ADS)

    Wu, Xiaohu; Fu, Ceji

    2018-04-01

    The wavevector of electromagnetic wave propagation in a hexagonal boron nitride (hBN) slab can be controlled by tilting its optical axis. This property can be used to manipulate the absorption in a hBN slab. By carefully analyzing the dependence of the absorptivity of a thin hBN slab on the tilted angle of its optical axis, we propose a structure that can realize great absorptivity enhancement in a band by stacking hBN slabs of different tilted angles. Our numerical results show that the absorptivity of a structure made of 91 stacked hBN slabs can be achieved higher than 0.94 in the wavenumber range from 1367 to 1580 cm-1 when the tilted angles of the slabs are properly arranged. The strong absorption is attributed to the combination of impedance matching at the slab interfaces and enlarged wavevectors in the slabs. This work reveals a novel way to realize strong absorption with anisotropic materials for applications in areas such as thermal radiative energy harvesting and conversion.

  19. Constructing aerial photo volume tables.

    Treesearch

    Robert B. Pope

    1962-01-01

    Although most foresters are familiar with the use of aerial photo volume tables, little has been written on how to make them. Certain pitfalls in the construction process have either been ignored or only casually mentioned in the existing literature. The forester tackling his first photo volume table is likely to bypass some of the important considerations without...

  20. Efficient and robust photo-ionization loading of beryllium ions

    NASA Astrophysics Data System (ADS)

    Wolf, Sebastian; Studer, Dominik; Wendt, Klaus; Schmidt-Kaler, Ferdinand

    2018-02-01

    We demonstrate the efficient generation of Be^+ ions with a 60 ns and 150 nJ laser pulse near 235 nm for two-step photo-ionization, proven by subsequent counting of the number of ions loaded into a linear Paul trap. The bandwidth and power of the laser pulse are chosen in such a way that a first, resonant step fully saturates the entire velocity distribution of beryllium atoms effusing from a thermal oven. The second excitation step is driven by the same light field causing efficient non-resonant ionization. Our ion-loading scheme has a similar efficiency as compared to former pathways using two-photon continuous wave laser excitation, but with an order of magnitude lower than average UV light power.