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Sample records for light induced degradation

  1. Light induced degradation of testosterone in waters

    Energy Technology Data Exchange (ETDEWEB)

    Vulliet, Emmanuelle, E-mail: e.vulliet@sca.cnrs.fr [Service Central d' Analyse du CNRS - USR59, Chemin du Canal, F-69360 Solaize (France); Falletta, Marine; Marote, Pedro [Laboratoire des Sciences Analytiques - UMR 5180, Universite Claude Bernard, 43 bd du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Lomberget, Thierry [Laboratoire de Chimie Therapeutique, Universite de Lyon, Universite Lyon 1, Faculte de Pharmacie-ISPB, EA 4443 Biomolecules, Cancer et Chimioresistances, INSERM U863 Hormones steroides et proteines de liaison, IFR 62, 8 avenue Rockefeller, F-69373, Lyon Cedex 08 (France); Paisse, Jean-Olivier; Grenier-Loustalot, Marie-Florence [Service Central d' Analyse du CNRS - USR59, Chemin du Canal, F-69360 Solaize (France)

    2010-08-01

    The degradation of testosterone under simulated irradiations was studied in phosphate buffers and in natural waters at various excitation wavelengths. The quantum yield of photolysis was significantly lower at 313 nm (2.4 x 10{sup -3}) than at 254 nm (0.225). The formation of several photoproducts was observed, some of them being rapidly transformed in turn while others show higher stability towards subsequent irradiations. The nature of the main products was tentatively identified, both deduced from their spectral and spectrometric data and by comparison with synthesised standard compounds. Among the obtained photoproducts, the main one is possibly a spiro-compound, hydroxylated derivative of testosterone originating from the photohydratation of the enone group. The photodegradation pathway includes also photorearrangements. One of them leads to (1,5,10)-cyclopropyl-17{beta}-hydroxyandrostane-2-one. The pH of the water does not seem to affect the rate of phototransformation and the nature of the by-products.

  2. Light induced degradation of phorbol esters.

    Science.gov (United States)

    Yunping, Bu; Ha, Bui Thi Ngoc; Eunice, Yeo; Chueng, Lo Loong; Yan, Hong

    2012-10-01

    Jatropha curcas (Jatropha) is a tropical shrub that is gaining popularity as a biofuel feedstock plant. Phorbol esters (PEs) are tetracyclic tiglian diterpenoids that are present in Jatropha seeds and other parts of plant. Epidermal cell irritating and cancer promoting PEs not only reduce commercial values of Jatropha seed cake but also cause some safety and environment concerns on PE leaching to soil. A simple bioassay of PE toxicity was conducted by incubating 48 h old brine shrimp (Artemia salina) nauplii with Jatropha oil for 24 h. 1-4% of Jatropha oil (corresponding to PE concentration of 25-100 mg L(-1)) had mortality rate of 5-95%, with LC50 estimated to be 2.7% of oil or 67 mg L(-1) of PE. Jatropha oil was incubated with clay or black soil (autoclaved or non-autoclaved) in the darkness or under sunlight for different periods of time before oil was re-extracted and tested for PE content by HPLC and for remaining toxicity with the brine shrimp bioassay. Under sunlight, PE decreased to non-detectable level within six days. Toxicity reduced to less than 5% mortality rate that is comparable to rapeseed oil control within the same period. In contrast, PE level and toxicity remained little changed when Jatropha oil was incubated in the darkness. Such PE degradation/detoxification was also found independent of the presence of soil or soil microorganisms. We conclude that sunlight directly degrades and detoxifies PEs and this finding should alleviate the concern on long term environmental impact of PE leaching. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Preventing light-induced degradation in multicrystalline silicon

    Science.gov (United States)

    Lindroos, J.; Boulfrad, Y.; Yli-Koski, M.; Savin, H.

    2014-04-01

    Multicrystalline silicon (mc-Si) is currently dominating the silicon solar cell market due to low ingot costs, but its efficiency is limited by transition metals, extended defects, and light-induced degradation (LID). LID is traditionally associated with a boron-oxygen complex, but the origin of the degradation in the top of the commercial mc-Si brick is revealed to be interstitial copper. We demonstrate that both a large negative corona charge and an aluminum oxide thin film with a built-in negative charge decrease the interstitial copper concentration in the bulk, preventing LID in mc-Si.

  4. Light-Induced Degradation of Thin Film Silicon Solar Cells

    International Nuclear Information System (INIS)

    Hamelmann, F U; Weicht, J A; Behrens, G

    2016-01-01

    Silicon-wafer based solar cells are still domination the market for photovoltaic energy conversion. However, most of the silicon is used only for mechanical stability, while only a small percentage of the material is needed for the light absorption. Thin film silicon technology reduces the material demand to just some hundred nanometer thickness. But even in a tandem stack (amorphous and microcrystalline silicon) the efficiencies are lower, and light-induced degradation is an important issue. The established standard tests for characterisation are not precise enough to predict the performance of thin film silicon solar cells under real conditions, since many factors do have an influence on the degradation. We will show some results of laboratory and outdoor measurements that we are going to use as a base for advanced modelling and simulation methods. (paper)

  5. Light-induced protein degradation in human-derived cells.

    Science.gov (United States)

    Sun, Wansheng; Zhang, Wenyao; Zhang, Chao; Mao, Miaowei; Zhao, Yuzheng; Chen, Xianjun; Yang, Yi

    2017-05-27

    Controlling protein degradation can be a valuable tool for posttranslational regulation of protein abundance to study complex biological systems. In the present study, we designed a light-switchable degron consisting of a light oxygen voltage (LOV) domain of Avena sativa phototropin 1 (AsLOV2) and a C-terminal degron. Our results showed that the light-switchable degron could be used for rapid and specific induction of protein degradation in HEK293 cells by light in a proteasome-dependent manner. Further studies showed that the light-switchable degron could also be utilized to mediate the degradation of secreted Gaussia princeps luciferase (GLuc), demonstrating the adaptability of the light-switchable degron in different types of protein. We suggest that the light-switchable degron offers a robust tool to control protein levels and may serves as a new and significant method for gene- and cell-based therapies. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Visible light induced photocatalytic degradation of some xanthene ...

    African Journals Online (AJOL)

    Photocatalytic degradation of eosin and erythrosin-B (xanthene dyes) has been carried out using anthracene semiconductor immobilized on polyethylene films. Effect of various parameters like pH, concentration of dyes, amount of semiconductor and light intensity have been studied on the rate of reaction. Various control ...

  7. Light-induced protein nitration and degradation with HONO emission

    Science.gov (United States)

    Meusel, Hannah; Elshorbany, Yasin; Kuhn, Uwe; Bartels-Rausch, Thorsten; Reinmuth-Selzle, Kathrin; Kampf, Christopher J.; Li, Guo; Wang, Xiaoxiang; Lelieveld, Jos; Pöschl, Ulrich; Hoffmann, Thorsten; Su, Hang; Ammann, Markus; Cheng, Yafang

    2017-10-01

    Proteins can be nitrated by air pollutants (NO2), enhancing their allergenic potential. This work provides insight into protein nitration and subsequent decomposition in the presence of solar radiation. We also investigated light-induced formation of nitrous acid (HONO) from protein surfaces that were nitrated either online with instantaneous gas-phase exposure to NO2 or offline by an efficient nitration agent (tetranitromethane, TNM). Bovine serum albumin (BSA) and ovalbumin (OVA) were used as model substances for proteins. Nitration degrees of about 1 % were derived applying NO2 concentrations of 100 ppb under VIS/UV illuminated conditions, while simultaneous decomposition of (nitrated) proteins was also found during long-term (20 h) irradiation exposure. Measurements of gas exchange on TNM-nitrated proteins revealed that HONO can be formed and released even without contribution of instantaneous heterogeneous NO2 conversion. NO2 exposure was found to increase HONO emissions substantially. In particular, a strong dependence of HONO emissions on light intensity, relative humidity, NO2 concentrations and the applied coating thickness was found. The 20 h long-term studies revealed sustained HONO formation, even when concentrations of the intact (nitrated) proteins were too low to be detected after the gas exchange measurements. A reaction mechanism for the NO2 conversion based on the Langmuir-Hinshelwood kinetics is proposed.

  8. Eliminating Light-Induced Degradation in Commercial p-Type Czochralski Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Brett Hallam

    2017-12-01

    Full Text Available This paper discusses developments in the mitigation of light-induced degradation caused by boron-oxygen defects in boron-doped Czochralski grown silicon. Particular attention is paid to the fabrication of industrial silicon solar cells with treatments for sensitive materials using illuminated annealing. It highlights the importance and desirability of using hydrogen-containing dielectric layers and a subsequent firing process to inject hydrogen throughout the bulk of the silicon solar cell and subsequent illuminated annealing processes for the formation of the boron-oxygen defects and simultaneously manipulate the charge states of hydrogen to enable defect passivation. For the photovoltaic industry with a current capacity of approximately 100 GW peak, the mitigation of boron-oxygen related light-induced degradation is a necessity to use cost-effective B-doped silicon while benefitting from the high-efficiency potential of new solar cell concepts.

  9. Microstructure, optical characterization and light induced degradation in a-Si:H deposited at different temperatures

    International Nuclear Information System (INIS)

    Minani, E.; Sigcau, Z.; Adgebite, O.; Ramukosi, F.L.; Ntsoane, T.P.; Harindintwari, S.; Knoesen, D.; Comrie, C.M.; Britton, D.T.; Haerting, M.

    2006-01-01

    The microstructure and optical properties of a series of hydrogenated amorphous silicon layers deposited on glass substrates at different temperature have been characterized by means of X-ray diffraction techniques and optical spectroscopy. The radial distribution function of the as-deposited samples showed an increase in the bond angle and a decrease in the radial distance indicating a relaxation of the amorphous network with increasing the deposition temperature. Light induced degradation was studied using a simulated daylight spectrum. The changes in hydrogen bonding configuration, associated with the light soaking at different stages of illumination, was monitored via the transmission bands of the vibrational wag and stretch modes of the IR spectrum

  10. Light-current-induced acceleration of degradation of methylammonium lead iodide perovskite solar cells

    Science.gov (United States)

    Xiang, Yuren; Zhang, Fan; He, Junjie; Lian, Jiarong; Zeng, Pengju; Song, Jun; Qu, Junle

    2018-04-01

    The photo-conversion efficiency of perovskite solar cells (PSCs) has been improved considerably in recent years, but the poor stability of PSCs still prevents their commercialization. In this report, we use the rate of the integrated short-circuit current change (Drate) to investigate the performance degradation kinetics and identify the degradation of PSCs that is accelerated by the light current. The value of Drate increases by an order of magnitude from about 0.02 to 0.35 mA cm-2·min-1 after light-IV testing. The accelerated degradation progress is proven to be dominated by the hydration process and the migration of the iodine ions of the light current. The migration of the iodine ions enhances the hydration process through a chain reaction, enabling the formation of fast diffusion channels for both H2O and O2, which induce the rapid decomposition of the perovskite film and increase the density of the trap state. The X-ray photoelectron spectroscopy measurement data also indicate that the super oxygen may be formed due to the PCBM damage caused by the migration iodine ions. An understanding of the degradation acceleration mechanism would provide an insight into the effect of ion migration on the stability of PSCs.

  11. Blue light induced free radicals from riboflavin in degradation of crystal violet by microbial viability evaluation.

    Science.gov (United States)

    Liang, Ji-Yuan; Yuann, Jeu-Ming P; Hsie, Zong-Jhe; Huang, Shiuh-Tsuen; Chen, Chiing-Chang

    2017-09-01

    Crystal violet (CV) is applied in daily use mainly as a commercial dye and antimicrobial agent. Waste water containing CV may affect aquatic ecosystems. Riboflavin, also known as vitamin B 2 , is non-toxic and an essential vitamin required for the functions of the human body. Riboflavin is photosensitive to UV and visible light in terms of generating reactive oxygen species. This study investigated the potential application of blue light on riboflavin, so as to come up with an effective way of degrading CV during its treatment. Photosensitivity of CV leading to degradation in the presence of riboflavin was investigated by light intensity, exposure time, and irradiation dosage. The degradation of CV during riboflavin photolysis treatment was studied by a UV/vis spectrometry and chromatography. The effects of CV degradation on microbial viability are relevant when considering the influences on the ecosystem. This study proved that riboflavin photochemical treatment with blue light degrades CV dye by ROS formation. The riboflavin photolysis-treated CV solution appeared to be transparent during conformational transformations of the CV that was rearranged by free radical species generated from riboflavin photolysis. After riboflavin photolysis, colony-forming units (CFUs) were determined for each CV solution. CFU preservation was 85.2% for the CV dissolved riboflavin solution treated with blue light irradiation at 2.0mW/cm 2 for 120min. Degradation of CV by riboflavin photochemical procedures can greatly reduce antimicrobial ability and serve as an environmental friendly waste water treatment method. Our results presented here concerning riboflavin photolysis in degradation of CV provide a novel technique, and a simple and safe practice for environmental decontamination processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Irradiation of skin with visible light induces reactive oxygen species and matrix-degrading enzymes.

    Science.gov (United States)

    Liebel, Frank; Kaur, Simarna; Ruvolo, Eduardo; Kollias, Nikiforos; Southall, Michael D

    2012-07-01

    Daily skin exposure to solar radiation causes cells to produce reactive oxygen species (ROS), which are a primary factor in skin damage. Although the contribution of the UV component to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology. Solar radiation comprises UV, and thus the purpose of this study was to examine the physiological response of skin to visible light (400-700 nm). Irradiation of human skin equivalents with visible light induced production of ROS, proinflammatory cytokines, and matrix metalloproteinase (MMP)-1 expression. Commercially available sunscreens were found to have minimal effects on reducing visible light-induced ROS, suggesting that UVA/UVB sunscreens do not protect the skin from visible light-induced responses. Using clinical models to assess the generation of free radicals from oxidative stress, higher levels of free radical activity were found after visible light exposure. Pretreatment with a photostable UVA/UVB sunscreen containing an antioxidant combination significantly reduced the production of ROS, cytokines, and MMP expression in vitro, and decreased oxidative stress in human subjects after visible light irradiation. Taken together, these findings suggest that other portions of the solar spectrum aside from UV, particularly visible light, may also contribute to signs of premature photoaging in skin.

  13. Nanoscale investigation of moisture-induced degradation mechanisms of tris(8-hydroxyquinoline) aluminium-based organic light-emitting diodes

    International Nuclear Information System (INIS)

    Xu, M S; Xu, J B; Chen, H Z; Wang, M

    2004-01-01

    By exploiting tapping mode atomic force microscopy, the moisture-induced degradation mechanisms of ITO (indium tin oxide)-coated glass/CuPc (copper phthalocyanine)/NPB (N, N'-di(naphthalene-1-yl)-N, N'-diphthalbenzidine)/Alq 3 (tris(8-hydroxyquinoline) aluminium)-based organic light-emitting diodes without cathode were investigated. It is found that three types of degradation mechanisms are associated with moisture-exposed Alq 3 films, when the device is exposed to moisture, namely, hydration of Alq 3 , crystallization of Alq 3 and reaction of the Alq 3 complex with H 2 O. Crystallization of the NPB layer of ITO/CuPc/NPB was observed on exposure to moisture, and de-wetting simultaneously takes place at the interface of CuPc/NPB. Indium and/or oxygen may diffuse from ITO into the organic layers. These observations provide a clear picture of the moisture-induced degradation mechanisms of the ITO/CuPc/NPB/Alq 3 -based OLEDs

  14. The photocatalytic degradation of methylene blue by green semiconductor films that is induced by irradiation by a light-emitting diode and visible light.

    Science.gov (United States)

    Yang, Chih-Chi; Doong, Ruey-An; Chen, Ku-Fan; Chen, Giin-Shan; Tsai, Yung-Pin

    2018-01-01

    This study develops a low-energy rotating photocatalytic contactor (LE-RPC) that has Cu-doped TiO 2 films coated on stainless-steel rotating disks, to experimentally evaluate the efficiency of the degradation and decolorization of methylene blue (MB) under irradiation from different light sources (visible 430 nm, light-emitting diode [LED] 460 nm, and LED 525 nm). The production of hydroxyl radicals is also examined. The experimental results show that the photocatalytic activity of TiO 2 that is doped with Cu 2+ is induced by illumination with visible light and an LED. More than 90% of methylene blue at a 10 mg/L concentration is degraded after illumination by visible light (430 nm) for 4 hr at 20 rpm. This study also demonstrates that the quantity of hydroxyl radicals produced is directly proportional to the light energy intensity. The greater the light energy intensity, the greater is the number of hydroxyl radicals produced. The CuO-doped anatase TiO 2 powder was successfully synthesized in this study by a sol-gel method. The catalytic abilities of the stainless-steel film were enhanced in the visible light regions. This study has successfully modified the nano-photocatalytic materials to drop band gap and has also successfully fixed the nano-photocatalytic materials on a substratum to effectively treat dye wastewater in the range of visible light. The results can be useful to the development of a low-energy rotating photocatalytic contactor for decontamination purposes.

  15. VUV/UV light inducing accelerated phenol degradation with a low electric input.

    Science.gov (United States)

    Li, Mengkai; Wen, Dong; Qiang, Zhimin; Kiwi, John

    2017-01-23

    This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4-6 min. The HO˙ and HO 2 ˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H 2 O 2 and Fe 3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H 2 O 2 or Fe 3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants.

  16. Fe(III)-solar light induced degradation of diethyl phthalate (DEP) in aqueous solutions.

    Science.gov (United States)

    Mailhot, G; Sarakha, M; Lavedrine, B; Cáceres, J; Malato, S

    2002-11-01

    The degradation of diethyl phthalate (DEP) photoinduced by Fe(III) in aqueous solutions has been investigated under solar irradiation in the compound parabolic collector reactor at Plataforma Solar de Almeria. Hydroxyl radicals *OH, responsible of the degradation, are formed via an intramolecular photoredox process in the excited state of Fe(III) aquacomplexes. The primary step of the reaction is mainly due to the attack of *OH radicals on the aromatic ring. For prolonged irradiations DEP and its photoproducts are completely mineralized due to the regeneration of the absorbing species and the continuous formation of *OH radicals that confers a catalytic aspect to the process. Consequently, the degradation photoinduced by Fe(III) could be an efficient method of DEP removal from water.

  17. Cu gettering by phosphorus-doped emitters in p-type silicon: Effect on light-induced degradation

    Science.gov (United States)

    Inglese, Alessandro; Laine, Hannu S.; Vähänissi, Ville; Savin, Hele

    2018-01-01

    The presence of copper (Cu) contamination is known to cause relevant light-induced degradation (Cu-LID) effects in p-type silicon. Due to its high diffusivity, Cu is generally regarded as a relatively benign impurity, which can be readily relocated during device fabrication from the wafer bulk, i.e. the region affected by Cu-LID, to the surface phosphorus-doped emitter. This contribution examines in detail the impact of gettering by industrially relevant phosphorus layers on the strength of Cu-LID effects. We find that phosphorus gettering does not always prevent the occurrence of Cu-LID. Specifically, air-cooling after an isothermal anneal at 800°C results in only weak impurity segregation to the phosphorus-doped layer, which turns out to be insufficient for effectively mitigating Cu-LID effects. Furthermore, we show that the gettering efficiency can be enhanced through the addition of a slow cooling ramp (-4°C/min) between 800°C and 600°C, resulting in the nearly complete disappearance of Cu-LID effects.

  18. Simulation of light-induced degradation of μc-Si in a-Si/μc-Si tandem solar cells by the diode equivalent circuit

    Science.gov (United States)

    Weicht, J. A.; Hamelmann, F. U.; Behrens, G.

    2016-02-01

    Silicon-based thin film tandem solar cells consist of one amorphous (a-Si) and one microcrystalline (μc-Si) silicon solar cell. The Staebler - Wronski effect describes the light- induced degradation and temperature-dependent healing of defects of silicon-based solar thin film cells. The solar cell degradation depends strongly on operation temperature. Until now, only the light-induced degradation (LID) of the amorphous layer was examined in a-Si/μc-Si solar cells. The LID is also observed in pc-Si single function solar cells. In our work we show the influence of the light-induced degradation of the μc-Si layer on the diode equivalent circuit. The current-voltage-curves (I-V-curves) for the initial state of a-Si/pc-Si modules are measured. Afterwards the cells are degraded under controlled conditions at constant temperature and constant irradiation. At fixed times the modules are measured at standard test conditions (STC) (AM1.5, 25°C cell temperature, 1000 W/m2) for controlling the status of LID. After the degradation the modules are annealed at dark conditions for several hours at 120°C. After the annealing the dangling bonds in the amorphous layer are healed, while the degradation of the pc-Si is still present, because the healing of defects in pc-Si solar cells needs longer time or higher temperatures. The solar cells are measured again at STC. With this laboratory measured I-V-curves we are able to separate the values of the diode model: series Rs and parallel resistance Rp, saturation current Is and diode factor n.

  19. Visible-light photocatalytic degradation of methylene blue with laser-induced Ag/ZnO nanoparticles

    International Nuclear Information System (INIS)

    Whang, Thou-Jen; Hsieh, Mu-Tao; Chen, Huang-Han

    2012-01-01

    The preparation of Ag doped ZnO nanoparticles conducted through the method of laser-induction is presented in this work. The Ag/ZnO nanoparticles attained from various weight percentages of added AgNO 3 relative to ZnO were applied under visible-light irradiation for evaluating the heterogeneous photocatalytic degradations of methylene blue (MB) solutions. It was shown that the catalytic behavior of Ag/ZnO nanoparticles in the visible-light range is notably improved through the Ag deposition onto ZnO nanoparticles by the method of laser-induction with a maximum effectiveness of 92% degradation. The properties of the nanoparticles were characterized by the employments of UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and selected-area electron diffraction (SAED).

  20. Effect of Rapid Thermal Processing on Light-Induced Degradation of Carrier Lifetime in Czochralski p-Type Silicon Bare Wafers

    Science.gov (United States)

    Kouhlane, Y.; Bouhafs, D.; Khelifati, N.; Belhousse, S.; Menari, H.; Guenda, A.; Khelfane, A.

    2016-11-01

    The electrical properties of Czochralski silicon (Cz-Si) p-type boron-doped bare wafers have been investigated after rapid thermal processing (RTP) with different peak temperatures. Treated wafers were exposed to light for various illumination times, and the effective carrier lifetime ( τ eff) measured using the quasi-steady-state photoconductance (QSSPC) technique. τ eff values dropped after prolonged illumination exposure due to light-induced degradation (LID) related to electrical activation of boron-oxygen (BO) complexes, except in the sample treated with peak temperature of 785°C, for which the τ eff degradation was less pronounced. Also, a reduction was observed when using the 830°C peak temperature, an effect that was enhanced by alteration of the wafer morphology (roughness). Furthermore, the electrical resistivity presented good stability under light exposure as a function of temperature compared with reference wafers. Additionally, the optical absorption edge shifted to higher wavelength, leading to increased free-carrier absorption by treated wafers. Moreover, a theoretical model is used to understand the lifetime degradation and regeneration behavior as a function of illumination time. We conclude that RTP plays an important role in carrier lifetime regeneration for Cz-Si wafers via modification of optoelectronic and structural properties. The balance between an optimized RTP cycle and the rest of the solar cell elaboration process can overcome the negative effect of LID and contribute to achievement of higher solar cell efficiency and module performance.

  1. Thermal degradation kinetics of all-trans and cis-carotenoids in a light-induced model system.

    Science.gov (United States)

    Xiao, Ya-Dong; Huang, Wu-Yang; Li, Da-Jing; Song, Jiang-Feng; Liu, Chun-Quan; Wei, Qiu-Yu; Zhang, Min; Yang, Qiu-Ming

    2018-01-15

    Thermal degradation kinetics of lutein, zeaxanthin, β-cryptoxanthin, β-carotene was studied at 25, 35, and 45°C in a model system. Qualitative and quantitative analyses of all-trans- and cis-carotenoids were conducted using HPLC-DAD-MS technologies. Kinetic and thermodynamic parameters were calculated by non-linear regression. A total of 29 geometrical isomers and four oxidation products were detected, including all-trans-, keto compounds, mono-cis- and di-cis-isomers. Degradations of all-trans-lutein, zeaxanthin, β-cryptoxanthin, and β-carotene were described by a first-order kinetic model, with the order of rate constants as k β -carotene >k β -cryptoxanthin >k lutein >k zeaxanthin . Activation energies of zeaxanthin, lutein, β-cryptoxanthin, and β-carotene were 65.6, 38.9, 33.9, and 8.6kJ/moL, respectively. cis-carotenoids also followed with the first-order kinetic model, but they did not show a defined sequence of degradation rate constants and activation energies at different temperatures. A possible degradation pathway of four carotenoids was identified to better understand the mechanism of carotenoid degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Degradation in organic light emitting devices

    Science.gov (United States)

    Dinh, Vincent Vinh

    This thesis is about the fundamental causes of degradation in tris(8-Hydroxyquinoline) Aluminum (Alq3)-based organic light emitting diodes (OLEDs). Degradation typically occurs when a current is forced through an insulating material. Since the insulator does not support conduction waves (in its ground state), chemical restructuring must occur to accommodate the current. OLEDs have many technical advantages over the well known semiconductor-based light emitting diodes (LEDs). OLEDs have quantum efficiencies ˜1% (˜10 times higher than the LEDs), and operational power thresholds ˜.05mW (˜100 lower than the LEDs). OLEDs are preferred in power limited and portable devices; devices such as laptops and displays consume ˜1/4 of the supplied power---any power saving is significant. Other advantages, like better compliance to curved surfaces and ease of fabrication, give the OLEDs an even greater edge over the LEDs. OLEDs must have at least comparable or better lifetimes to remain attractive. Typical OLEDs last several 100hrs compared to the several 1000hrs for the LEDs. For reliable OLED application, it is necessary to understand the above breakdown mechanism. In this thesis, we attempt to understand the breakdown by looking at how OLEDs are made, how they work, and when they don't. In the opening sections, we give an overview of OLEDs and LEDs, especially how sustained luminescence is achieved through current circulation. Then in Chapter 2, we look at the basic components in the OLEDs. In Chapter 3 we look at how a hole material (like poly-vinyl carbazole or PVK) establishes an excitonic environment for the sustained luminescence in Alq3. We then approximate how potential is distributed when a simple luminescence system is in operation. In Chapter 4, we look at ways of measuring this distribution via the OLED impedance. Finally in Chapter 5, we look at the OLED stability under light emission conditions via PVK and Alq3 photoemission and photoabsorption spectra

  3. Overview of environmental materials degradation in light-water reactors

    International Nuclear Information System (INIS)

    Shaaban, H.I.; Wu, P.

    1986-08-01

    This report provides a brief overview of analyses and conclusions reported in published literature regarding environmentally induced degradation of materials in operating light-water reactors. It is intended to provide a synopsis of subjects of concern rather than to address a licensing basis for any newly discovered problems related to reactor materials

  4. Unravelling Light-Induced Degradation of Layered Perovskite Crystals and Design of Efficient Encapsulation for Improved Photostability

    NARCIS (Netherlands)

    Fang, Hong-Hua; Yang, Jie; Tao, Shuxia; Adjokatse, Sampson; Kamminga, Machteld E.; Ye, Jianting; Blake, Graeme; Even, Jacky; Loi, Maria Antoinetta

    2018-01-01

    Layered halide perovskites have recently shown extraordinary potential for low‐cost solution‐processable optoelectronic applications because of their superior moisture stability over their 3D counterparts. However, few studies have investigated the effect of light on layered hybrid perovskites.

  5. Phytohormone and Light Regulation of Chlorophyll Degradation

    Directory of Open Access Journals (Sweden)

    Xiaoyu Zhu

    2017-11-01

    Full Text Available Degreening, due to the net loss of chlorophyll (Chl, is the most prominent symptom during the processes of leaf senescence, fruit ripening, and seed maturation. Over the last decade or so, extensive identifications of Chl catabolic genes (CCGs have led to the revelation of the biochemical pathway of Chl degradation. As such, exploration of the regulatory mechanism of the degreening process is greatly facilitated. During the past few years, substantial progress has been made in elucidating the regulation of Chl degradation, particularly via the mediation of major phytohormones' signaling. Intriguingly, ethylene and abscisic acid's signaling have been demonstrated to interweave with light signaling in mediating the regulation of Chl degradation. In this review, we briefly summarize this progress, with an effort on providing a framework for further investigation of multifaceted and hierarchical regulations of Chl degradation.

  6. Thermal stress during RTP processes and its possible effect on the light induced degradation in Cz-Si wafers

    Science.gov (United States)

    Kouhlane, Yacine; Bouhafs, Djoudi; Khelifati, Nabil; Guenda, Abdelkader; Demagh, Nacer-Eddine; Demagh, Assia; Pfeiffer, Pierre; Mezghiche, Salah; Hetatache, Warda; Derkaoui, Fahima; Nasraoui, Chahinez; Nwadiaru, Ogechi Vivian

    2018-04-01

    In this study, the carrier lifetime variation of p-type boron-doped Czochralski silicon (Cz-Si) wafers was investigated after a direct rapid thermal processing (RTP). Two wafers were passivated by silicon nitride (SiNx:H) layers, deposited by a PECVD system on both surfaces. Then the wafers were subjected to an RTP cycle at a peak temperature of 620 °C. The first wafer was protected (PW) from the direct radiative heating of the RTP furnace by placing the wafer between two as-cut Cz-Si shield wafers during the heat processing. The second wafer was not protected (NPW) and followed the same RTP cycle procedure. The carrier lifetime τ eff was measured using the QSSPC technique before and after illumination for 5 h duration at 0.5 suns. The immediate results of the measured lifetime (τ RTP ) after the RTP process have shown a regeneration in the lifetime of the two wafers with the PW wafer exhibiting an important enhancement in τ RTP as compared to the NPW wafer. The QSSPC measurements have indicated a good stable lifetime (τ d ) and a weak degradation effect was observed in the case of the PW wafer as compared to their initial lifetime value. Interferometry technique analyses have shown an enhancement in the surface roughness for the NPW wafer as compared to the protected one. Additionally, to improve the correlation between the RTP heat radiation stress and the carrier lifetime behavior, a simulation of the thermal stress and temperature profile using the finite element method on the wafers surface at RTP peak temperature of 620 °C was performed. The results confirm the reduction of the thermal stress with less heat losses for the PW wafer. Finally, the proposed method can lead to improving the lifetime of wafers by an RTP process at minimum energy costs.

  7. Light and current induced degradation in p-type multi-crystalline cells and development of an inspection method and a stabilization method

    Energy Technology Data Exchange (ETDEWEB)

    Broek, K.M.; Bennett, I.J.; Jansen, M.J.; Borg, Van der N.J.C.M.; Eerenstein, W. [ECN Solar Energy, Petten (Netherlands)

    2012-09-15

    Stable solar cells are needed for durability testing of different combinations of module materials. In such a test, significant power losses in full-size modules with multi-crystalline cells after thermal cycling have been observed. This has been related to degradation of the solar cells used and it appeared that this was caused by current induced degradation. This phenomenon is not limited to boron doped Cz-Si, but can also occur in p-type multi-crystalline silicon. Work was done to develop an incoming inspection method for new batches of cells. Also, stabilisation procedures for modules containing cells that are sensitive to degradation have been determined.

  8. A first-principles model of copper-boron interactions in Si: implications for the light-induced degradation of solar Si

    Science.gov (United States)

    Wright, E.; Coutinho, J.; Öberg, S.; Torres, V. J. B.

    2017-02-01

    The recent discovery that Cu contamination of Si combined with light exposure has a significant detrimental impact on carrier life-time has drawn much concern within the solar-Si community. The effect, known as the copper-related light-induced degradation (Cu-LID) of Si solar cells, has been connected to the release of Cu interstitials within the bulk (2016 Sol. Energy Mater. Sol. Cells 147 115-26). In this paper, we describe a comprehensive analysis of the formation/dissociation process of the CuB pair in Si by means of first-principles modelling, as well as the interaction of CuB defects with photo-excited minority carriers. We confirm that the long-range interaction between the \\text{Cu}\\text{i}+ cation and the \\text{B}\\text{s}- anion has a Coulomb-like behaviour, in line with the trapping-limited diffusivity of Cu observed by transient ion drift measurements. On the other hand, the short-range interaction between the d-electrons of Cu and the excess of negative charge on \\text{B}\\text{s}- produces a repulsive effect, thereby decreasing the binding energy of the pair when compared to the ideal point-charge Coulomb model. We also find that metastable CuB pairs produce acceptor states just below the conduction band minimum, which arise from the Cu level emptied by the B acceptor. Based on these results, we argue that photo-generated minority carriers trapped by the metastable pairs can switch off the Coulomb interaction that holds the pairs together, enhancing the release of Cu interstitials, and acting as a catalyst for Cu-LID.

  9. Visible light-induced photocatalytic degradation of Reactive Blue-19 over highly efficient polyaniline-TiO2 nanocomposite: a comparative study with solar and UV photocatalysis.

    Science.gov (United States)

    Kalikeri, Shankramma; Kamath, Nidhi; Gadgil, Dhanashri Jayant; Shetty Kodialbail, Vidya

    2018-02-01

    Polyaniline-TiO 2 (PANI-TiO 2 ) nanocomposite was prepared by in situ polymerisation method. X-ray diffractogram (XRD) showed the formation of PANI-TiO 2 nanocomposite with the average crystallite size of 46 nm containing anatase TiO 2 . The PANI-TiO 2 nanocomposite consisted of short-chained fibrous structure of PANI with spherical TiO 2 nanoparticles dispersed at the tips and edge of the fibres. The average hydrodynamic diameter of the nanocomposite was 99.5 nm. The band gap energy was 2.1 eV which showed its ability to absorb light in the visible range. The nanocomposite exhibited better visible light-mediated photocatalytic activity than TiO 2 (Degussa P25) in terms of degradation of Reactive Blue (RB-19) dye. The photocatalysis was favoured under initial acidic pH, and complete degradation of 50 mg/L dye could be achieved at optimum catalyst loading of 1 g/L. The kinetics of degradation followed the Langmuir-Hinshelhood model. PANI-TiO 2 nanocomposite showed almost similar photocatalytic activity under UV and visible light as well as in the solar light which comprises of radiation in both UV and visible light range. Chemical oxygen demand removal of 86% could also be achieved under visible light, confirming that simultaneous mineralization of the dye occurred during photocatalysis. PANI-TiO 2 nanocomposites are promising photocatalysts for the treatment of industrial wastewater containing RB-19 dye.

  10. Determination of the light-induced degradation rate of the solar cell sensitizer N719 on TiO2 nanocrystalline particles

    DEFF Research Database (Denmark)

    Nour-Mohammadi, Farahnaz; Doan Nguyen, Sau; Boschloo, Gerrit

    2005-01-01

    The oxidative degradation rate, kdeg of the solar cell dye (Bu4N+)2 [Ru(dcbpyH)2(NCS)2]2–, referred to as N719 or [RuL2(NCS)2], was obtained by applying a simple model system. Colloidal solutions of N719-dyed TiO2 particles in acetonitrile were irradiated with 532-nm monochromatic light, and the ...

  11. Entanglement degradation in depolarizing light scattering

    International Nuclear Information System (INIS)

    Aiello, A.; Woerdman, J.P.

    2005-01-01

    Full text: In the classical regime, when a beam of light is scattered by a medium, it may emerge partially or completely depolarized depending on the optical properties of the medium. Correspondingly, in the quantum regime, when an entangled two-photon pair is scattered, the classical depolarization may result in an entanglement degradation. Here, relations between photon scattering, entanglement and multi-mode detection are investigated. We establish a general framework in which one- and two-photon elastic scattering processes can be discussed, and we focus on the study of the intrinsic entanglement degradation caused by a multi-mode detection. We show that any multi-mode scattered state cannot maximally violate the Bell-CHSH inequality because of the momentum spread. The results presented here have general validity and can be applied to both deterministic and random scattering processes. (author)

  12. Visible Light-Induced Degradation of Methylene Blue in the Presence of Photocatalytic ZnS and CdS Nanoparticles

    Directory of Open Access Journals (Sweden)

    Parisa Vaziri

    2012-09-01

    Full Text Available ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under mild conditions. The obtained nanoparticles were characterized by XRD, TEM and EDX. The results indicated that high purity of nanosized ZnS and CdS was successfully obtained with cubic and hexagonal crystalline structures, respectively. The band gap energies of ZnS and CdS nanoparticles were estimated using UV-visible absorption spectra to be about 4.22 and 2.64 eV, respectively. Photocatalytic degradation of methylene blue was carried out using physical mixtures of ZnS and CdS nanoparticles under a 500-W halogen lamp of visible light irradiation. The residual concentration of methylene blue solution was monitored using UV-visible absorption spectrometry. From the study of the variation in composition of ZnS:CdS, a composition of 1:4 (by weight was found to be very efficient for degradation of methylene blue. In this case the degradation efficiency of the photocatalyst nanoparticles after 6 h irradiation time was about 73% with a reaction rate of 3.61 × 10−3 min−1. Higher degradation efficiency and reaction rate were achieved by increasing the amount of photocatalyst and initial pH of the solution.

  13. Metastable light induced defects in pentacene

    Energy Technology Data Exchange (ETDEWEB)

    Liguori, R.; Aprano, S.; Rubino, A. [Department of Industrial Engineering (DIIn), University of Salerno, via Giovanni Paolo II, 132, 84084 Fisciano (Italy)

    2014-02-21

    In this study we analyzed one of the environmental factors that could affect organic materials. Pentacene thin film samples were fabricated and the degradation of their electrical characteristics was measured when the devices were exposed to ultraviolet light irradiation. The results have been reported in terms of a trap density model, which provides a description of the dynamics of light induced electrically active defects in an organic semiconductor.

  14. Preparation of reduced graphene oxide/meso-TiO_2/AuNPs ternary composites and their visible-light-induced photocatalytic degradation n of methylene blue

    International Nuclear Information System (INIS)

    Yang, Yongfang; Ma, Zheng; Xu, Lidong; Wang, Hefang; Fu, Nian

    2016-01-01

    Graphical abstract: Reduced graphene oxide/meso-TiO_2/AuNPs (RGO/meso-TiO_2/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO_2/AuNPs under a hydrothermal condition. The RGO/meso-TiO_2/AuNPs ternary composites show high photocatalytic activity toward MB. - Highlights: • RGO/meso-TiO_2/AuNPs were obtained by addition of graphene oxide to meso-TiO_2/AuNPs. • Au NPs in the mesopores of meso-TiO_2 reduce the recombination of charge carriers. • RGO covered with the surface of the meso-TiO_2 enhance the adsorption of MB. • RGO/meso-TiO_2/AuNPs composites show high photocatalytic performance toward MB. - Abstract: Reduced graphene oxide/meso-TiO_2/AuNPs (RGO/meso-TiO_2/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO_2/AuNPs under hydrothermal conditions. The structure and the morphology of the RGO/meso-TiO_2/AuNPs materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of RGO/meso-TiO_2/AuNPs was evaluated by degradation of methyl blue (MB) under visible-light illumination. The ternary composites present an extended light absorption range, efficient charge separation properties, high adsorption ability for MB and high photocatalytic degradation activity of MB compared to the meso-TiO_2 and meso-TiO_2/AuNPs.

  15. Preparation of reduced graphene oxide/meso-TiO{sub 2}/AuNPs ternary composites and their visible-light-induced photocatalytic degradation n of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yongfang; Ma, Zheng; Xu, Lidong [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Wang, Hefang, E-mail: whf0618@163.com [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); Fu, Nian, E-mail: funian3678@163.com [School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130 (China); College of Physics Science and Technology of Hebei University, Baoding 071002 (China)

    2016-04-30

    Graphical abstract: Reduced graphene oxide/meso-TiO{sub 2}/AuNPs (RGO/meso-TiO{sub 2}/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO{sub 2}/AuNPs under a hydrothermal condition. The RGO/meso-TiO{sub 2}/AuNPs ternary composites show high photocatalytic activity toward MB. - Highlights: • RGO/meso-TiO{sub 2}/AuNPs were obtained by addition of graphene oxide to meso-TiO{sub 2}/AuNPs. • Au NPs in the mesopores of meso-TiO{sub 2} reduce the recombination of charge carriers. • RGO covered with the surface of the meso-TiO{sub 2} enhance the adsorption of MB. • RGO/meso-TiO{sub 2}/AuNPs composites show high photocatalytic performance toward MB. - Abstract: Reduced graphene oxide/meso-TiO{sub 2}/AuNPs (RGO/meso-TiO{sub 2}/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO{sub 2}/AuNPs under hydrothermal conditions. The structure and the morphology of the RGO/meso-TiO{sub 2}/AuNPs materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of RGO/meso-TiO{sub 2}/AuNPs was evaluated by degradation of methyl blue (MB) under visible-light illumination. The ternary composites present an extended light absorption range, efficient charge separation properties, high adsorption ability for MB and high photocatalytic degradation activity of MB compared to the meso-TiO{sub 2} and meso-TiO{sub 2}/AuNPs.

  16. Green synthesis of the reduced graphene oxide–CuI quasi-shell–core nanocomposite: A highly efficient and stable solar-light-induced catalyst for organic dye degradation in water

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jiha; Reddy, D. Amaranatha; Islam, M. Jahurul [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609-735 (Korea, Republic of); Seo, Bora [Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Joo, Sang Hoon [Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Kim, Tae Kyu, E-mail: tkkim@pusan.ac.kr [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609-735 (Korea, Republic of)

    2015-12-15

    Graphical abstract: - Highlights: • Green synthesis of RGO–CuI quasi-shell–core nanocomposites without any surfactant. • Promising candidates as solar light active photocatalyst for dye degradation. • Significant improvement of the photocatalytic activity in RGO wrapped composites. • The best photocatalytic activity to RhB has been attained for CuI–RGO (2 mg mL{sup −1}). - Abstract: Surfactant-free, reduced graphene oxide (RGO)–CuI quasi-shell−core nanocomposites were successfully synthesized using ultra-sonication assisted chemical method at room temperature. The morphologies, structures and optical properties of the CuI and CuI–RGO nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), UV–visible absorption spectroscopy, and photoluminescence (PL) spectroscopy. Morphological and structural analyses indicated that the CuI–RGO core–shell nanocomposites comprise single-crystalline face-centered cubic phase CuI nanostructures, coated with a thin RGO quasi-shell. Photocatalysis experiments revealed that the as-synthesized CuI–RGO nanocomposites exhibit remarkably enhanced photocatalytic activities and stabilities for photo degradation of Rhodamine-B (RhB) organic dye under simulated solar light irradiation. The photo degradation ability is strongly affected by the concentration of RGO in the nanocomposites; the highest photodegradation rate was obtained at a graphene loading content of 2 mg mL{sup −1} nanocomposite. The remarkable photocatalytic performance of the CuI–RGO nanocomposites mainly originates from their unique adsorption and electron-accepting and electron-transporting properties of RGO. The present work provides a novel green synthetic route to producing CuI–RGO nanocomposites without toxic solvents or reducing agents, thereby providing highly efficient and stable solar light-induced

  17. Green synthesis of the reduced graphene oxide–CuI quasi-shell–core nanocomposite: A highly efficient and stable solar-light-induced catalyst for organic dye degradation in water

    International Nuclear Information System (INIS)

    Choi, Jiha; Reddy, D. Amaranatha; Islam, M. Jahurul; Seo, Bora; Joo, Sang Hoon; Kim, Tae Kyu

    2015-01-01

    Graphical abstract: - Highlights: • Green synthesis of RGO–CuI quasi-shell–core nanocomposites without any surfactant. • Promising candidates as solar light active photocatalyst for dye degradation. • Significant improvement of the photocatalytic activity in RGO wrapped composites. • The best photocatalytic activity to RhB has been attained for CuI–RGO (2 mg mL −1 ). - Abstract: Surfactant-free, reduced graphene oxide (RGO)–CuI quasi-shell−core nanocomposites were successfully synthesized using ultra-sonication assisted chemical method at room temperature. The morphologies, structures and optical properties of the CuI and CuI–RGO nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared spectroscopy (FTIR), UV–visible absorption spectroscopy, and photoluminescence (PL) spectroscopy. Morphological and structural analyses indicated that the CuI–RGO core–shell nanocomposites comprise single-crystalline face-centered cubic phase CuI nanostructures, coated with a thin RGO quasi-shell. Photocatalysis experiments revealed that the as-synthesized CuI–RGO nanocomposites exhibit remarkably enhanced photocatalytic activities and stabilities for photo degradation of Rhodamine-B (RhB) organic dye under simulated solar light irradiation. The photo degradation ability is strongly affected by the concentration of RGO in the nanocomposites; the highest photodegradation rate was obtained at a graphene loading content of 2 mg mL −1 nanocomposite. The remarkable photocatalytic performance of the CuI–RGO nanocomposites mainly originates from their unique adsorption and electron-accepting and electron-transporting properties of RGO. The present work provides a novel green synthetic route to producing CuI–RGO nanocomposites without toxic solvents or reducing agents, thereby providing highly efficient and stable solar light-induced RGO

  18. Intimate Coupling of Photocatalysis and Biodegradation for Degrading Phenol Using Different Light Types: Visible Light vs UV Light.

    Science.gov (United States)

    Zhou, Dandan; Xu, Zhengxue; Dong, Shanshan; Huo, Mingxin; Dong, Shuangshi; Tian, Xiadi; Cui, Bin; Xiong, Houfeng; Li, Tingting; Ma, Dongmei

    2015-07-07

    Intimate coupling of photocatalysis and biodegradation (ICPB) technology is attractive for phenolic wastewater treatment, but has only been investigated using UV light (called UPCB). We examined the intimate coupling of visible-light-induced photocatalysis and biodegradation (VPCB) for the first time. Our catalyst was prepared doping both of Er(3+) and YAlO3 into TiO2 which were supported on macroporous carriers. The macroporous carriers was used to support for the biofilms as well. 99.8% removal efficiency of phenol was achieved in the VPCB, and this was 32.6% higher than that in the UPCB. Mineralization capability of UPCB was even worse, due to less adsorbable intermediates and cell lysis induced soluble microbial products release. The lower phenol degradation in the UPCB was due to the serious detachment of the biofilms, and then the microbes responsible for phenol degradation were insufficient due to disinfection by UV irradiation. In contrast, microbial communities in the carriers were well protected under visible light irradiation and extracellular polymeric substances secretion was enhanced. Thus, we found that the photocatalytic reaction and biodegradation were intimately coupled in the VPCB, resulting in 64.0% removal of dissolved organic carbon. Therefore, we found visible light has some advantages over UV light in the ICPB technology.

  19. A thermo-degradable hydrogel with light-tunable degradation and drug release.

    Science.gov (United States)

    Hu, Jingjing; Chen, Yihua; Li, Yunqi; Zhou, Zhengjie; Cheng, Yiyun

    2017-01-01

    The development of thermo-degradable hydrogels is of great importance in drug delivery. However, it still remains a huge challenge to prepare thermo-degradable hydrogels with inherent degradation, reproducible, repeated and tunable dosing. Here, we reported a thermo-degradable hydrogel that is rapidly degraded above 44 °C by a facile chemistry. Besides thermo-degradability, the hydrogel also undergoes rapid photolysis with ultraviolet light. By embedding photothermal nanoparticles or upconversion nanoparticles into the gel, it can release the entrapped cargoes such as dyes, enzymes and anticancer drugs in an on-demand and dose-tunable fashion upon near-infrared light exposure. The smart hydrogel works well both in vitro and in vivo without involving sophisticated syntheses, and is well suited for clinical cancer therapy due to the high transparency and non-invasiveness features of near-infrared light. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Concentrated Light for Accelerated Photo Degradation of Polymer Materials

    DEFF Research Database (Denmark)

    Madsen, Morten Vesterager; Tromholt, Thomas; Norrman, Kion

    2013-01-01

    Concentrated light is used to perform photochemical degradation of polymer solar cell materials with acceleration factors up to 1200. At constant temperature the photon efficiency in regards to photo degradation is constant for 1–150 suns and oxygen diffusion rates are not a limiting factor...

  1. Degradation of light emitting diodes: a proposed methodology

    International Nuclear Information System (INIS)

    Koh, Sau; Vam Driel, Willem; Zhang, G.Q.

    2011-01-01

    Due to their long lifetime and high efficacy, light emitting diodes have the potential to revolutionize the illumination industry. However, self heat and high environmental temperature which will lead to increased junction temperature and degradation due to electrical overstress can shorten the life of the light emitting diode. In this research, a methodology to investigate the degradation of the LED emitter has been proposed. The epoxy lens of the emitter can be modelled using simplified Eyring methods whereas an equation has been proposed for describing the degradation of the LED emitters. (semiconductor devices)

  2. Development of Amorphous/Microcrystalline Silicon Tandem Thin-Film Solar Modules with Low Output Voltage, High Energy Yield, Low Light-Induced Degradation, and High Damp-Heat Reliability

    Directory of Open Access Journals (Sweden)

    Chin-Yi Tsai

    2014-01-01

    Full Text Available In this work, tandem amorphous/microcrystalline silicon thin-film solar modules with low output voltage, high energy yield, low light-induced degradation, and high damp-heat reliability were successfully designed and developed. Several key technologies of passivation, transparent-conducting-oxide films, and cell and segment laser scribing were researched, developed, and introduced into the production line to enhance the performance of these low-voltage modules. A 900 kWp photovoltaic system with these low-voltage panels was installed and its performance ratio has been simulated and projected to be 92.1%, which is 20% more than the crystalline silicon and CdTe counterparts.

  3. Land Tenure Induced Deforestation and Environmental Degradation ...

    African Journals Online (AJOL)

    Land Tenure Induced Deforestation and Environmental Degradation in Ethiopia: The Case of Arbagugu State Forest Development and Protection Project (A ... The objective of this paper is to explore the cause and impact of this overarching problem by focusing on Arbagugu State Forest Development and Protection Project, ...

  4. Chlorophyll b degradation by chlorophyll b reductase under high-light conditions.

    Science.gov (United States)

    Sato, Rei; Ito, Hisashi; Tanaka, Ayumi

    2015-12-01

    The light-harvesting chlorophyll a/b binding protein complex of photosystem II (LHCII) is the main antenna complex of photosystem II (PSII). Plants change their LHCII content depending on the light environment. Under high-light conditions, the content of LHCII should decrease because over-excitation damages the photosystem. Chlorophyll b is indispensable for accumulating LHCII, and chlorophyll b degradation induces LHCII degradation. Chlorophyll b degradation is initiated by chlorophyll b reductase (CBR). In land plants, NON-YELLOW COLORING 1 (NYC1) and NYC1-Like (NOL) are isozymes of CBR. We analyzed these mutants to determine their functions under high-light conditions. During high-light treatment, the chlorophyll a/b ratio was stable in the wild-type (WT) and nol plants, and the LHCII content decreased in WT plants. The chlorophyll a/b ratio decreased in the nyc1 and nyc1/nol plants, and a substantial degree of LHCII was retained in nyc1/nol plants after the high-light treatment. These results demonstrate that NYC1 degrades the chlorophyll b on LHCII under high-light conditions, thus decreasing the LHCII content. After the high-light treatment, the maximum quantum efficiency of the PSII photochemistry was lower in nyc1 and nyc1/nol plants than in WT and nol plants. A larger light-harvesting system would damage PSII in nyc1 and nyc1/nol plants. The fluorescence spectroscopy of the leaves indicated that photosystem I was also damaged by the excess LHCII in nyc1/nol plants. These observations suggest that chlorophyll b degradation by NYC1 is the initial reaction for the optimization of the light-harvesting capacity under high-light conditions.

  5. Constitutive and ligand-induced TCR degradation

    DEFF Research Database (Denmark)

    von Essen, Marina; Bonefeld, Charlotte Menné; Siersma, Volkert

    2004-01-01

    Modulation of TCR expression levels is a central event during T cell development and activation, and it probably plays an important role in adjusting T cell responsiveness. Conflicting data have been published on down-regulation and degradation rates of the individual TCR subunits, and several di...... to the lysosomes. Similar results were obtained in studies of primary human Vbeta8+ T cells stimulated with superantigen. Based on these results, the simplest model for TCR internalization, sorting, and degradation is proposed.......Modulation of TCR expression levels is a central event during T cell development and activation, and it probably plays an important role in adjusting T cell responsiveness. Conflicting data have been published on down-regulation and degradation rates of the individual TCR subunits, and several...... divergent models for TCR down-regulation and degradation have been suggested. The aims of this study were to determine the rate constants for constitutive and ligand-induced TCR degradation and to determine whether the TCR subunits segregate or are processed as an intact unit during TCR down...

  6. Radiation-induced degradation of pollutants

    International Nuclear Information System (INIS)

    Proksch, E.

    1988-01-01

    This article outlines the fundamentals of radiation-induced degradation of noxious substances in drinking water and waste water and discusses the relevant literature. Radiation methods present a number of advantages and disadvantages, which should carefully be considered in each case. In many cases, there seems to be merit in combining the radiation method with other techniques, as e.g. ozone treatement and biodegradation. 30 refs., 3 figs. (Author)

  7. Degradation of Methylammonium Lead Iodide Perovskite Structures through Light and Electron Beam Driven Ion Migration

    Science.gov (United States)

    2016-01-01

    Organometal halide perovskites show promising features for cost-effective application in photovoltaics. The material instability remains a major obstacle to broad application because of the poorly understood degradation pathways. Here, we apply simultaneous luminescence and electron microscopy on perovskites for the first time, allowing us to monitor in situ morphology evolution and optical properties upon perovskite degradation. Interestingly, morphology, photoluminescence (PL), and cathodoluminescence of perovskite samples evolve differently upon degradation driven by electron beam (e-beam) or by light. A transversal electric current generated by a scanning electron beam leads to dramatic changes in PL and tunes the energy band gaps continuously alongside film thinning. In contrast, light-induced degradation results in material decomposition to scattered particles and shows little PL spectral shifts. The differences in degradation can be ascribed to different electric currents that drive ion migration. Moreover, solution-processed perovskite cuboids show heterogeneity in stability which is likely related to crystallinity and morphology. Our results reveal the essential role of ion migration in perovskite degradation and provide potential avenues to rationally enhance the stability of perovskite materials by reducing ion migration while improving morphology and crystallinity. It is worth noting that even moderate e-beam currents (86 pA) and acceleration voltages (10 kV) readily induce significant perovskite degradation and alter their optical properties. Therefore, attention has to be paid while characterizing such materials using scanning electron microscopy or transmission electron microscopy techniques. PMID:26804213

  8. Synthesis and characterization of C-doped TiO{sub 2} thin films for visible-light-induced photocatalytic degradation of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Mohamed Elfatih; Cong, Longchao; Liu, Guanglong, E-mail: liugl@mail.hzau.edu.cn; Zhu, Duanwei; Cai, Jianbo

    2014-03-01

    Graphical abstract: - Highlights: • C-TiO{sub 2} thin films were successfully synthesized by modified sol–gel method based on the self-assembly technique. • Tween 80, one kind of hydrocarbon surfactants, was used as template and carbon precursor. • A thorough material characterization was performed to determine the effect of calcination time on the structural and optical properties of the synthesized catalyst films. - Abstract: C-TiO{sub 2} thin films were synthesized by a modified sol–gel route based on the self-assembly technique exploiting Tween80 (T80) as a pore directing agent and carbon source. The effect of calcination time on the photocatalytic activity of C-doped TiO{sub 2} catalyst was studied. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FTIR), UV–vis diffuse reflectance spectroscopy, and photoluminescence spectra (PL). The XRD results showed that C-TiO{sub 2} sample calcined at 400 °C for various times exhibited anatase phase and no other crystal phase was identified. C-TiO{sub 2} exhibited a shift in an absorption edge of samples in the visible region than that of conventional or reference TiO{sub 2}. The XPS results showed an existence of C in the TiO{sub 2} catalysts and C might be existed as C-O-Ti group. Moreover, the C-TiO{sub 2} thin film calcined at 400 °C for 30 min showed the lowest PL intensity due to a decrease in the recombination rate of photogenerated electrons and holes under UV light irradiation. Also the photocatalytic activity of synthesized catalyst was evaluated by decomposition of methyl orange (MO) under visible light irradiation. The results showed that the optimum preparations of C-TiO{sub 2} thin films were found to be under calcination temperature of 400, calcination time of 30 min, and with preparation 9 layers film.

  9. Degradation of phosphorescent blue organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Chien-Shu [Department of Electrical Engineering and Information Technology, Technical University of Braunschweig (Germany); Siemens AG, CT MM 1, Erlangen (Germany); Steinbacher, Frank [Department of Materials Science VI, University of Erlangen-Nuernberg (Germany); Siemens AG, CT MM 1, Erlangen (Germany); Krause, Ralf; Hunze, Arvid [Siemens AG, CT MM 1, Erlangen (Germany); Kowalsky, Wolfgang [Department of Electrical Engineering and Information Technology, Technical University of Braunschweig (Germany)

    2009-07-01

    Development of phosphorescent materials has significantly improved the efficiency of organic light-emitting diodes (OLEDs). By using efficient red, green and blue phosphorescent emitter materials high efficient white OLEDs can be achieved. However, due to low stability of blue phosphorescent materials the lifetime of phosphorescent white OLEDs remains an issue. As a result, degradation of blue phosphorescent materials needs to be further investigated and improved. In this work, blue OLED devices based on the phosphorescent emitter FIrpic were investigated. Single-carrier hole-only as well as electron-only devices were fabricated. For investigation of degradation process the devices were stressed with electrical current and UV-light to study the impact of charge carriers as well as excitons and exciton-polaron quenching on the stability of the blue dye.

  10. Gamma Irradiation Induced Degradation of Orange Peels

    Directory of Open Access Journals (Sweden)

    Jaime Saucedo Luna

    2012-08-01

    Full Text Available In this study, gamma irradiation induced degradation of orange peels (OP was investigated. The lignocellulosic biomass degradation was carried out at doses of 0 (control, 600, 1800 and 3500 kGy using a Co-60 gamma radiation source. The samples were tested for total and reducing sugars. The concentrations of total sugars ranged from 0.530 g∙g−1 in control sample to 0.382 g∙g−1 of dry weight in the sample which received the highest radiation dose. The reducing sugars content varying from 0.018 to 0.184 g∙g−1 of dry weight with the largest rise occurring in the sample irradiated at 3500 kGy. The concentrations of sucrose, glucose and fructose were determined. The changes generated in physico-chemical properties were determined by Fourier Transform Infrared Spectroscopy (FTIR and termogravimetric analysis (TG-DTG. The results show that OP was affected, but not significantly, which suggests that lignocellulose and sugars profiles were partially degraded after gamma irradiation.

  11. VISIBLE LIGHT INDUCED PHOTOCATALYTIC DEGRADATION OF ...

    African Journals Online (AJOL)

    a

    Solar Energy and Photochemistry Laboratory, Department of Chemistry, University College ..... singlet state which then undergo intersystem crossing to their triplet state. ... are removed by the dissolved molecular oxygen to produce superoxide.

  12. Degradation of phosphorescent blue organic light-emitting diodes (OLED); Degradation der phosphoreszenten blauen organischen Leuchtdioden

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Chien-Shu

    2011-07-01

    Phosphorescent organic materials harvest singlet and triplet excitons through inter-system crossing and improve the efficiency of organic light-emitting diodes (OLEDs). This improvement increases the potential of OLEDs, particularly white phosphorescent OLEDs (PHOLEDs), for lighting application. Although much progress has been made in the development of white PHOLEDs, the lifetime of phosphorescent emitters, especially the blue emitter, still needs to be improved. This thesis discusses the developments of blue PHOLEDs and investigations of degradation mechanisms. For development of blue PHOLEDs, two phosphorescent blue emitters were investigated: commercially available FIrpic and B1 provided by BASF. By varying the matrix and blocker materials, diode efficiency and lifetime have been investigated and improved. Blue PHOLEDs with emitter B1 show better efficiency and lifetime than devices with FIrpic. From lifetime measurement with constant DC current density, intrinsic degradation including luminance loss and voltage increase on both FIrpic and B1 PHOLEDs was observed. Photoluminescence measurement shows degradation in the emitting layers. To investigate the degradation of emitter layers, single-carrier devices with emitter systems or pure matrix materials were fabricated. Degradation on these devices was investigated by applying constant DC current, UV-irradiation and combination of both. We found that due to excited states (excitons), FIrpic molecules become unstable and polarons would enhance the degradation of FIrpic during DC operation and UV-excitation. To investigate the impact the exciton formation and exciton decay have on the degradation of FIrpic molecules, red phosphorescent emitter Ir(MDQ){sub 2}(acac) was doped in blue emitter layer TCTA:20% FIrpic. The doping concentration of Ir(MDQ){sub 2}(acac) was much lower than FIrpic to ensure that most of the exciton formation occurred on FIrpic molecules. Lower triplet energy of Ir(MDQ){sub 2}(acac) molecules

  13. Mutations induced by ultraviolet light

    International Nuclear Information System (INIS)

    Pfeifer, Gerd P.; You, Young-Hyun; Besaratinia, Ahmad

    2005-01-01

    The different ultraviolet (UV) wavelength components, UVA (320-400 nm), UVB (280-320 nm), and UVC (200-280 nm), have distinct mutagenic properties. A hallmark of UVC and UVB mutagenesis is the high frequency of transition mutations at dipyrimidine sequences containing cytosine. In human skin cancers, about 35% of all mutations in the p53 gene are transitions at dipyrimidines within the sequence 5'-TCG and 5'-CCG, and these are localized at several mutational hotspots. Since 5'-CG sequences are methylated along the p53 coding sequence in human cells, these mutations may be derived from sunlight-induced pyrimidine dimers forming at sequences that contain 5-methylcytosine. Cyclobutane pyrimidine dimers (CPDs) form preferentially at dipyrimidines containing 5-methylcytosine when cells are irradiated with UVB or sunlight. In order to define the contribution of 5-methylcytosine to sunlight-induced mutations, the lacI and cII transgenes in mouse fibroblasts were used as mutational targets. After 254 nm UVC irradiation, only 6-9% of the base substitutions were at dipyrimidines containing 5-methylcytosine. However, 24-32% of the solar light-induced mutations were at dipyrimidines that contain 5-methylcytosine and most of these mutations were transitions. Thus, CPDs forming preferentially at dipyrimidines with 5-methylcytosine are responsible for a considerable fraction of the mutations induced by sunlight in mammalian cells. Using mouse cell lines harboring photoproduct-specific photolyases and mutational reporter genes, we showed that CPDs (rather than 6-4 photoproducts or other lesions) are responsible for the great majority of UVB-induced mutations. An important component of UVB mutagenesis is the deamination of cytosine and 5-methylcytosine within CPDs. The mutational specificity of long-wave UVA (340-400 nm) is distinct from that of the shorter wavelength UV and is characterized mainly by G to T transversions presumably arising through mechanisms involving oxidized DNA

  14. Solid-phase photocatalytic degradation of polyethylene-goethite composite film under UV-light irradiation

    International Nuclear Information System (INIS)

    Liu, G.L.; Zhu, D.W.; Liao, S.J.; Ren, L.Y.; Cui, J.Z.; Zhou, W.B.

    2009-01-01

    A novel photodegradable polyethylene-goethite (PE-goethite) composite film was prepared by embedding the goethite into the commercial polyethylene. The degradation of PE-goethite composite films was investigated under ultraviolet light irradiation. The photodegradation activity of the PE plastic was determined by monitoring its weight loss, scanning electron microscopic (SEM) analysis and FT-IR spectroscopy. The weight of PE-goethite (1 wt%) sample steadily decreased and led to the total 16% reduction in 300 h under UV-light intensity for 1 mW/cm 2 . Through SEM observation there were some cavities around the goethite powder in the composite films, but there were few changes except some surface chalking phenomenon in pure PE film. The degradation rate could be controlled by changing the concentration of goethite particles in PE plastic. The degradation of composite plastic initiated on PE-goethite interface and then extended into polymer matrix induced by the diffusion of the reactive oxygen species generated on goethite particle surface. The photocatalytic degradation mechanism of the composite films was briefly discussed.

  15. UV Light Induces Dedoping of Polyaniline

    Directory of Open Access Journals (Sweden)

    Yuki Kaitsuka

    2016-01-01

    Full Text Available UV (Ultra-Violet light-driven change in optical absorption of polyaniline (PANI is reported. Irradiation of UV light to PANI/camphor sulfonic acid prepared by electrochemical polymerization allows dedoping of the PANI. Especially, UV light irradiation in the presence of a radical trap agent effectively reduces (dedoping the PANI. The result in this study is quite simple; however, this may be a first report for light-induced dedoping (color change of a conductive polymer.

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

    International Nuclear Information System (INIS)

    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 φ D (riboflavin, pH 8) ∼ 7.8 x 10 -3 , φ D (FMN, pH 5.6) ∼ 7.3 x 10 -3 , φ D (FMN, pH 8) ∼ 4.6 x 10 -3 , φ D (FAD, pH 8) ∼ 3.7 x 10 -4 , φ D (lumichrome, pH 8) ∼ 1.8 x 10 -4 , and φ D (lumiflavin, pH 8) approx. 1.1 x 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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Holzer, W. [Institut II-Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Shirdel, J. [Institut II-Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Zirak, P. [Institut II-Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A. [Institut II-Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany)]. E-mail: alfons.penzkofer@physik.uni-regensburg.de; Hegemann, P. [Institut fuer Biochemie I, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Deutzmann, R. [Institut fuer Biochemie I, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany); Hochmuth, E. [Institut fuer Biochemie I, Universitaet Regensburg, Universitaetsstrasse 31, D-93053 Regensburg (Germany)

    2005-01-10

    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 {phi}{sub D}(riboflavin, pH 8) {approx} 7.8 x 10{sup -3}, {phi}{sub D}(FMN, pH 5.6) {approx} 7.3 x 10{sup -3}, {phi}{sub D}(FMN, pH 8) {approx} 4.6 x 10{sup -3}, {phi}{sub D}(FAD, pH 8) {approx} 3.7 x 10{sup -4}, {phi}{sub D}(lumichrome, pH 8) {approx} 1.8 x 10{sup -4}, and {phi}{sub D}(lumiflavin, pH 8) approx. 1.1 x 10{sup -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.

  19. Mineral induced mechanochemical degradation: the imazaquin case.

    Science.gov (United States)

    Nasser, Ahmed; Buchanovsky, Nadia; Gerstl, Zev; Mingelgrin, Uri

    2009-03-01

    The potential role of mechanochemical processes in enhancing degradation of imazaquin by soil components is demonstrated. The investigated components include montmorillonite saturated with Na(+), Ca(2+), Cu(2+)and Al(3+), Agsorb (a commercial clay mix), birnessite and hematite. The mechanical force applied was manual grinding of mixtures of imazaquin and the minerals, using mortar and pestle. The degradation rates of imazaquin in these mixtures were examined as a function of the following parameters: time of grinding, herbicide load (3.9, 8.9, 16.7 and 26.6 mg imazaquin per g mineral), temperature (10, 25, 40 and 70 degrees C), acidic/basic conditions, and dry or wet grinding. Dry grinding of imazaquin for 5 min with Al-montmorillonite or with hematite resulted in 56% and 71% degradation of the imazaquin, respectively. Wet grinding slightly reduced the degradation rate with hematite and entirely cancelled the enhancing effect of grinding with Al-montmorillonite. Wet grinding in the presence of the transition metals: Ni(2+), Cu(2+), Fe(3+) added as chlorides was carried out. Addition of Cu(2+) to Na-montmorillonite loaded with imazaquin was the most effective treatment in degrading imazaquin (more than 90% of the imazaquin degraded after 5 min of grinding). In this treatment, Cu-montmorillonite formation during the grinding process was confirmed by XRD and accordingly, grinding with Cu-montmorillonite gave similar degradation values. LC-MS analysis revealed that the mechanochemical transformation of imazaquin resulted in the formation of a dimer and several breakdown products. The reported results demonstrate once again that mechanochemical procedures offer a remediation avenue applicable to soils polluted with organic contaminants.

  20. Global Assessment of Human-induced Soil Degradation (GLASOD)

    NARCIS (Netherlands)

    Oldeman, L.R.; Hakkeling, R.T.A.; Sombroek, W.G.; Batjes, N.H.

    2014-01-01

    The GLASOD project (1987-1990) has produced a world map of human-induced soil degradation. Data were complied in cooperation with a large number of soil scientists throughout the world, using uniform Guidelines and international correlation. The status of soil degradation was mapped within loosely

  1. Sunlight-Induced Photochemical Degradation of Methylene Blue by Water-Soluble Carbon Nanorods

    Directory of Open Access Journals (Sweden)

    Anshu Bhati

    2016-01-01

    Full Text Available Water-soluble graphitic hollow carbon nanorods (wsCNRs are exploited for their light-driven photochemical activities under outdoor sunlight. wsCNRs were synthesized by a simple pyrolysis method from castor seed oil, without using any metal catalyst or template. wsCNRs exhibited the light-induced photochemical degradation of methylene blue used as a model pollutant by the generation of singlet oxygen species. Herein, we described a possible degradation mechanism of methylene blue under the irradiation of visible photons via the singlet oxygen-superoxide anion pathway.

  2. Study of thermal degradation of organic light emitting device structures by X-ray scattering

    International Nuclear Information System (INIS)

    Lee, Young-Joo; Lee, Heeju; Byun, Youngsuk; Song, Sanghoon; Kim, Je-Eun; Eom, Daeyong; Cha, Wonsuk; Park, Seong-Sik; Kim, Jinwoo; Kim, Hyunjung

    2007-01-01

    We report the process of thermal degradation of organic light emitting devices (OLEDs) having multilayered structure of [LiF/tris-(8-hydroxyquinoline) aluminum(Alq 3 )/N,N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB)/copper phthalocyanine (CuPc)/indium tin oxide (ITO)/SiO 2 on a glass] by synchrotron X-ray scattering. The results show that the thermally induced degradation process of OLED multilayers has undergone several evolutions due to thermal expansion of NPB, intermixing between NPB, Alq 3 , and LiF layers, dewetting of NPB on CuPc, and crystallization of NPB and Alq 3 depending on the annealing temperature. The crystallization of NPB appears at 180 deg. C, much higher temperature than the glass transition temperature (T g = 96 deg. C) of NPB. The results are also compared with the findings from the atomic force microscope (AFM) images

  3. Degradation of polycarbonate induced by gamma radiation

    International Nuclear Information System (INIS)

    Araujo, E.S. de; Guedes, S.M.L.

    1992-01-01

    Polycarbonate (PC) DUROLON amorphous, of molecular weight 22000 g/mol is used in medical supplies and may be sterilized by gamma radiation. The main chain scission and polymer degradation occur when this polymer is irradiated. The value G = 1.54 to DUROLON was obtained by equation: 10 6 /M v = 10 6 /M v' + 0.054 G R. The degradation without crosslinking it is not general rule to all types of polycarbonates; an comparison was realized. The infrared (FT-IR) spectra of irradiated PC by gamma rays with different doses showed the main chain scissions in carbonyl groups. The mechanism of polymeric degradation to DUROLON, observed by NMR spectra, is a recombination of phenoxy and phenyl radicals. (author)

  4. Degradation of Polymers by Ultra-Violet Light

    Energy Technology Data Exchange (ETDEWEB)

    Turner, D. T. [Camille Dreyfus Laboratory, Research Triangle Institute, Research Triangle Park, NC (United States)

    1968-10-15

    To reach an understanding of the complex processes which occur when polymers are degraded by ultra-violet light under service conditions it is first judicious to try to elucidate the photochemistry of relatively simple polymer reactions. For this reason, emphasis is given to studies in which purified polymers, in bulk, were exposed to monochromatic radiations in the absence of oxygen. In respect of product analysis, emphasis is given to methods for estimating quantum yields for fractures and crosslinks. Photochemical mechanisms are illustrated by discussion of polystyrene, polytethylene terephthalate) and cellulose. Special emphasis is given to the role of free radicals. Attention is drawn to reports that the course of photolysis may be changed by application of an external pressure of a chemically inert gas, such as nitrogen. The explanation suggested in the literature is that this depends on the ease of escape of hydrogen atoms which, alternatively, might react with trapped polymer radicals. The course of photolysis may also be affected by polymer radicals acting as strongly absorbing chromophores and consequently undergoing further chemical reaction. This is illustrated by reference to the conversion of allyl radicals to alkyl radicals in polyethylene and also by changes observed in the ESR spectrum of polymer radicals trapped in poly (ethylene terephthalate) as a result of exposure to light. It is suggested that this effect is primarily responsible for the evolution of hydrocarbon gases on photolysis of polyethylene or natural rubber. In contrast, radiolysis of these polymers yields almost pure hydrogen because, in this case, energy is absorbed by relatively non-selective processes, i.e. free radicals do not absorb high energy radiation much more strongly than does their polymeric environment. (author)

  5. Light-induced defects in hybrid lead halide perovskite

    Science.gov (United States)

    Sharia, Onise; Schneider, William

    One of the main challenges facing organohalide perovskites for solar application is stability. Solar cells must last decades to be economically viable alternatives to traditional energy sources. While some causes of instability can be avoided through engineering, light-induced defects can be fundamentally limiting factor for practical application of the material. Light creates large numbers of electron and hole pairs that can contribute to degradation processes. Using ab initio theoretical methods, we systematically explore first steps of light induced defect formation in methyl ammonium lead iodide, MAPbI3. In particular, we study charged and neutral Frenkel pair formation involving Pb and I atoms. We find that most of the defects, except negatively charged Pb Frenkel pairs, are reversible, and thus most do not lead to degradation. Negative Pb defects create a mid-gap state and localize the conduction band electron. A minimum energy path study shows that, once the first defect is created, Pb atoms migrate relatively fast. The defects have two detrimental effects on the material. First, they create charge traps below the conduction band. Second, they can lead to degradation of the material by forming Pb clusters.

  6. Collinear light scattering using electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Harris, S.E.; Sokolov, A.V.; Walker, D.R.; Yavuz, D.D.; Yin, G.Y.

    2001-01-01

    The paper describes two types of nonlinear optical processes which are based on electromagnetically induced transparency. These are: (1) Collinear generation of FM-like Raman sidebands and (2) a type of pondermotive light scattering which is inherent to the interaction of slow light with cold atoms. Connections to other areas of EIT-based nonlinear optics are also described

  7. Radiation-induced degradation of galactomannan polysaccharides

    International Nuclear Information System (INIS)

    Sen, Murat; Yolacan, Burcu; Gueven, Olgun

    2007-01-01

    In this study, guar gum, tara gum and locust bean gum were irradiated in a gamma cell in the solid state. The change in their molecular weights were determined by size exclusion chromatography analysis and the change in their viscosity values with change of temperature and irradiation dose were determined. Chain scission yield, G(s), and degradation rate values were calculated. The calculated G(s) values is 1.09 ± 0.16, 1.07 ± 0.06, 0.85 ± 0.10 for GG, TG and LBG, respectively. The effect of mannose-galactose ratio and initial molecular weight of these gums on the degradation behavior were discussed

  8. Hydroxyl radical induced degradation of ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Illés, Erzsébet, E-mail: erzsebet.illes@chem.u-szeged.hu [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Takács, Erzsébet [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary); Dombi, András [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Gajda-Schrantz, Krisztina [Institute of Chemistry, Research Group of Environmental Chemistry, University of Szeged, Szeged (Hungary); Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged (Hungary); EMPA, Laboratory for High Performance Ceramics, Duebendorf (Switzerland); Rácz, Gergely; Gonter, Katalin; Wojnárovits, László [Institute of Isotopes, Centre for Energy Research, Hungarian Academy of Sciences, Budapest (Hungary)

    2013-03-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1 mmol dm{sup −3}. For end product characterization {sup 60}Co γ-irradiation was used and the samples were evaluated either by taking their UV–vis spectra or by HPLC with UV or MS detection. The reactions of {sup ·}OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose. Highlights: ► In hydroxyl radical attack on the ring mainly hydroxylated products form ► The hydrated electron attacks the carboxyl group. ► Oxidative conditions are more effective in ibuprofen decomposition than reductive. ► Ecotoxicity of ibuprofen solution first increases then decreases with irradiation.

  9. Hydroxyl radical induced degradation of ibuprofen

    International Nuclear Information System (INIS)

    Illés, Erzsébet; Takács, Erzsébet; Dombi, András; Gajda-Schrantz, Krisztina; Rácz, Gergely; Gonter, Katalin; Wojnárovits, László

    2013-01-01

    Pulse radiolysis experiments were used to characterize the intermediates formed from ibuprofen during electron beam irradiation in a solution of 0.1 mmol dm −3 . For end product characterization 60 Co γ-irradiation was used and the samples were evaluated either by taking their UV–vis spectra or by HPLC with UV or MS detection. The reactions of · OH resulted in hydroxycyclohexadienyl type radical intermediates. The intermediates produced in further reactions hydroxylated the derivatives of ibuprofen as final products. The hydrated electron attacked the carboxyl group. Ibuprofen degradation is more efficient under oxidative conditions than under reductive conditions. The ecotoxicity of the solution was monitored by Daphnia magna standard microbiotest and Vibrio fischeri luminescent bacteria test. The toxic effect of the aerated ibuprofen solution first increased upon irradiation indicating a higher toxicity of the first degradation products, then decreased with increasing absorbed dose. Highlights: ► In hydroxyl radical attack on the ring mainly hydroxylated products form ► The hydrated electron attacks the carboxyl group. ► Oxidative conditions are more effective in ibuprofen decomposition than reductive. ► Ecotoxicity of ibuprofen solution first increases then decreases with irradiation

  10. Geochemical induced degradation of environmental chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Parlar, H

    1984-09-01

    Attempts to correlate the concentration of organic chemicals in the environment with their production figures have resulted in a large deficit; this includes environmental chemicals such as chlorinated hydrocarbons. It has been assumed that analytical errors accounted for this deficit. Another explanation, however, allows for reactions of compounds under biotic and abiotic conditions. Because of the biostability of many organic chemicals biological transformation mechanisms can bring about slight change only. By contrast, abiotic environmental factors such as the UV-irradiation or decomposition on natural surfaces contribute considerably to the transformation of this substance class. An investigation of such abiotic charges of organic chemicals must therefore pay particular attention to dynamic and catalytic effects primarily attributable to the respective molecular state and interactions with the environment. This paper deals with the photoinduced reactions of organic substances adsorbed on natural surfaces and their significance for the degradability of environmental chemicals.

  11. Analyzing degradation effects of organic light-emitting diodes via transient optical and electrical measurements

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Tobias D., E-mail: Tobias.Schmidt@physik.uni-augsburg.de; Jäger, Lars; Brütting, Wolfgang, E-mail: Wolfgang.Bruetting@physik.uni-augsburg.de [Institute of Physics, University of Augsburg, Augsburg (Germany); Noguchi, Yutaka [Department of Electronics and Bioinformatics, School of Science and Technology, Meiji University, Kawasaki (Japan); Center of Frontier Science, Chiba University, Chiba (Japan); Ishii, Hisao [Center of Frontier Science, Chiba University, Chiba (Japan)

    2015-06-07

    Although the long-term stability of organic light-emitting diodes (OLEDs) under electrical operation made significant progress in recent years, the fundamental underlying mechanisms of the efficiency decrease during operation are not well understood. Hence, we present a comprehensive degradation study of an OLED structure comprising the well-known green phosphorescent emitter Ir(ppy){sub 3}. We use transient methods to analyze both electrical and optical changes during an accelerated aging protocol. Combining the results of displacement current measurements with time-resolved investigation of the excited states lifetimes of the emitter allows for a correlation of electrical (e.g., increase of the driving voltage due to trap formation) and optical (e.g., decrease of light-output) changes induced by degradation. Therewith, it is possible to identify two mechanisms resulting in the drop of the luminance: a decrease of the radiative quantum efficiency of the emitting system due to triplet-polaron-quenching at trapped charge carriers and a modified charge carrier injection and transport, as well as trap-assisted non-radiative recombination resulting in a deterioration of the charge carrier balance of the device.

  12. Laser induced white lighting of tungsten filament

    Science.gov (United States)

    Strek, W.; Tomala, R.; Lukaszewicz, M.

    2018-04-01

    The sustained bright white light emission of thin tungsten filament was induced under irradiation with focused beam of CW infrared laser diode. The broadband emission centered at 600 nm has demonstrated the threshold behavior on excitation power. Its intensity increased non-linearly with excitation power. The emission occurred only from the spot of focused beam of excitation laser diode. The white lighting was accompanied by efficient photocurrent flow and photoelectron emission which both increased non-linearly with laser irradiation power.

  13. Microbial degradation of resins fractionated from Arabian light crude oil

    International Nuclear Information System (INIS)

    Venkateswaran, K.; Hoaki, T.; Kato, M.; Maruyama, T.

    1995-01-01

    Sediment samples from the Japanese coasts were screened for microorganisms able to degrade resin components of crude oil. A mixed population that could degrade 35% of 5000 ppm resin in 15 days was obtained. This population also metabolized 50% of saturates and aromatics present in crude oil (5000 ppm) in 7 days. A Pseudomonas sp., isolated from the mixed population, emulsified and degraded 30% of resins. It also degraded saturates and aromatics (30%) present in crude oil (5000 ppm). These results were obtained from Iatroscan analysis. Degradation of crude oil was also analyzed by gas chromatography (GC). The peaks corresponding to known aliphatic hydrocarbons in crude oil greatly decreased within the first two days of incubation in the cultures of the RY-mixed population and of Pseudomonas strain UN3. Aromatic compounds detected as a broad peak by GC were significantly degraded at day 7 by Pseudomonas strain UN3, and at day 15 by the RY-mixed population. Investigations are ongoing to determine the genetic basis for the ability of these organisms to grow on the resin fractions of crude oil as a sole source of carbon and energy. 28 refs., 4 figs., 1 tab

  14. Degradation of malachite green on Pd/WO3 photocatalysts under simulated solar light

    International Nuclear Information System (INIS)

    Liu Yonggang; Ohko, Yoshihisa; Zhang Ruiqin; YangYingnan; Zhang Zhenya

    2010-01-01

    The photocatalytic degradation of malachite green (MG) dye molecules in aqueous solution was investigated by using palladium (Pd) modified tungsten trioxide (WO 3 ) under simulated solar light. The optimum values for Pd content vs. WO 3 and catalyst concentration in solution for MG (5.0 μmol L -1 ) degradation were 0.5 wt.% and 150 mg L -1 , respectively. The MG concentration change followed the pseudo first order kinetics of the Langmuir-Hinshelwood model. Since MG was also degraded under visible light (λ > 470 nm), which was not absorbed by WO 3 , the mechanism involved both the photocatalytic degradation and self-sensitized degradation of MG. Pd modified WO 3 would be useful as an efficient tool for the decolorization of wastewater under solar light.

  15. Materials Degradation in Light Water Reactors: Life After 60,

    International Nuclear Information System (INIS)

    Busby, Jeremy T; Nanstad, Randy K; Stoller, Roger E; Feng, Zhili; Naus, Dan J

    2008-01-01

    Nuclear reactors present a very harsh environment for components service. Components within a reactor core must tolerate high temperature water, stress, vibration, and an intense neutron field. Degradation of materials in this environment can lead to reduced performance, and in some cases, sudden failure. A recent EPRI-led study interviewed 47 US nuclear utility executives to gauge perspectives on long-term operation of nuclear reactors. Nearly 90% indicated that extensions of reactor lifetimes to beyond 60 years were likely. When polled on the most challenging issues facing further life extension, two-thirds cited plant reliability as the key issue with materials aging and cable/piping as the top concerns for plant reliability. Materials degradation within a nuclear power plant is very complex. There are many different types of materials within the reactor itself: over 25 different metal alloys can be found with can be found within the primary and secondary systems, not to mention the concrete containment vessel, instrumentation and control, and other support facilities. When this diverse set of materials is placed in the complex and harsh environment coupled with load, degradation over an extended life is indeed quite complicated. To address this issue, the USNRC has developed a Progressive Materials Degradation Approach (NUREG/CR-6923). This approach is intended to develop a foundation for appropriate actions to keep materials degradation from adversely impacting component integrity and safety and identify materials and locations where degradation can reasonably be expected in the future. Clearly, materials degradation will impact reactor reliability, availability, and potentially, safe operation. Routine surveillance and component replacement can mitigate these factors, although failures still occur. With reactor life extensions to 60 years or beyond or power uprates, many components must tolerate the reactor environment for even longer times. This may increase

  16. Laboratory based degradation of light crude oil by aquatic ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-08-18

    Aug 18, 2009 ... This spilled oil produces destructive effect on the environment. For example, when ... growth was separated from the oil using gas chromatography. The hydrocarbon that dissolved in carbon tetrachloride ... Gasoline and gas oil were also degraded (Figure 1). ACKNOWLEDGEMENT. The authors wish to ...

  17. VUV/UV light inducing accelerated phenol degradation with a low electric input† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6ra26043h Click here for additional data file.

    Science.gov (United States)

    Li, Mengkai; Wen, Dong

    2017-01-01

    This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4–6 min. The HO˙ and HO2˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H2O2 and Fe3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H2O2 or Fe3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants. PMID:28496972

  18. Transition in complex calcium bursting induced by IP3 degradation

    International Nuclear Information System (INIS)

    Zhang Feng; Lu Qishao; Su Jianzhong

    2009-01-01

    Complex intracellular Ca 2+ oscillations are systematically investigated in a mathematical model based on the mechanism of Ca 2+ -induced Ca 2+ release (CICR), taking account of the Ca 2+ -stimulated degradation of inositol 1,4,5-trisphosphate (IP 3 ) by a 3-kinase. Periodic, quasi-periodic and chaotic bursting oscillations exist in a wide range of parameter values and occur alternatively as the parameters change slightly. The transition among them can be observed by the evidence in their interspike interval and the Lyapunov exponent. These results reveal the role of agonist-stimulated of IP 3 degradation as a possible source for complex patterns in Ca 2+ signaling.

  19. Light-induced performance increase of silicon heterojunction solar cells

    KAUST Repository

    Kobayashi, Eiji; De Wolf, Stefaan; Levrat, Jacques; Christmann, Gabriel; Descoeudres, Antoine; Nicolay, Sylvain; Despeisse, Matthieu; Watabe, Yoshimi; Ballif, Christophe

    2016-01-01

    Silicon heterojunction solar cells consist of crystalline silicon (c-Si) wafers coated with doped/intrinsic hydrogenated amorphous silicon (a-Si:H) bilayers for passivating-contact formation. Here, we unambiguously demonstrate that carrier injection either due to light soaking or (dark) forward-voltage bias increases the open circuit voltage and fill factor of finished cells, leading to a conversion efficiency gain of up to 0.3% absolute. This phenomenon contrasts markedly with the light-induced degradation known for thin-film a-Si:H solar cells. We associate our performance gain with an increase in surface passivation, which we find is specific to doped a-Si:H/c-Si structures. Our experiments suggest that this improvement originates from a reduced density of recombination-active interface states. To understand the time dependence of the observed phenomena, a kinetic model is presented.

  20. Light-induced performance increase of silicon heterojunction solar cells

    KAUST Repository

    Kobayashi, Eiji

    2016-10-11

    Silicon heterojunction solar cells consist of crystalline silicon (c-Si) wafers coated with doped/intrinsic hydrogenated amorphous silicon (a-Si:H) bilayers for passivating-contact formation. Here, we unambiguously demonstrate that carrier injection either due to light soaking or (dark) forward-voltage bias increases the open circuit voltage and fill factor of finished cells, leading to a conversion efficiency gain of up to 0.3% absolute. This phenomenon contrasts markedly with the light-induced degradation known for thin-film a-Si:H solar cells. We associate our performance gain with an increase in surface passivation, which we find is specific to doped a-Si:H/c-Si structures. Our experiments suggest that this improvement originates from a reduced density of recombination-active interface states. To understand the time dependence of the observed phenomena, a kinetic model is presented.

  1. Radiation induced degradation of DNA in photodynamic therapy of cancer

    International Nuclear Information System (INIS)

    Ion, Rodica; Scarlat, F.; Niculescu, V.I.R.; Scarlat, Fl.; Gunaydin, Keriman

    2001-01-01

    DNA is a critical cellular target for oxidative processes induced by physical and chemical stresses. It is known that the direct effect of ionizing radiation on DNA results mainly in base ionization and may lead to mutation, carcinogenesis and cell death. The degradation of DNA induced by laser and ionizing radiation (electron and photon beam) is analyzed in this paper. The ionizing radiation degradation of DNA is a radical process. A series of lesions among the major base degradation product has been measured in isolated DNA exposed to gamma radiation in aerated aqueous solution. Degradation can be accounted for by the formation of hydroxyl radicals upon radiolysis of water (indirect effect). The production of DNA damage by ionizing radiation involves two mechanisms, direct and indirect effects. Direct effect leads to ionization and excitation of DNA molecules, while indirect effect is due to the interaction of reactive species, in particular of OH radicals produced by water radiolysis, with targets in DNA. The relative contribution of the two mechanisms in damaging DNA depends on the type of radiation. Single strand breaks and base damage seem to be mainly produced by the attack of hydroxyl radicals on DNA, whereas double strand breaks result predominantly of direct energy deposition. The four bases are degraded in high yield. Direct effect has been mimicked by photo-induced electron abstraction from the bases producing their radical cation. The base damage may also occur from the formation of radical cation of purine and pyrimidine components. When DNA is irradiated in solution, single strand breaks are mainly due to the abstraction of an H atom from the 4 ' position of 2 ' -deoxyribose by the attack of OH radicals produced by water radiolysis. Quantification of the modified bases showed the guanine is the preferential target. Ionizing radiation induces several types of DNA modifications, including chain breaks, DNA-protein cross-links, oxidized DNA bases

  2. Study on scalable Coulombic degradation for estimating the lifetime of organic light-emitting devices

    International Nuclear Information System (INIS)

    Zhang Wenwen; Hou Xun; Wu Zhaoxin; Liang Shixiong; Jiao Bo; Zhang Xinwen; Wang Dawei; Chen Zhijian; Gong Qihuang

    2011-01-01

    The luminance decays of organic light-emitting diodes (OLEDs) are investigated with initial luminance of 1000 to 20 000 cd m -2 through a scalable Coulombic degradation and a stretched exponential decay. We found that the estimated lifetime by scalable Coulombic degradation deviates from the experimental results when the OLEDs work with high initial luminance. By measuring the temperature of the device during degradation, we found that the higher device temperatures will lead to instabilities of organic materials in devices, which is expected to result in the difference between the experimental results and estimation using the scalable Coulombic degradation.

  3. Degradation effects of the active region in UV-C light-emitting diodes

    Science.gov (United States)

    Glaab, Johannes; Haefke, Joscha; Ruschel, Jan; Brendel, Moritz; Rass, Jens; Kolbe, Tim; Knauer, Arne; Weyers, Markus; Einfeldt, Sven; Guttmann, Martin; Kuhn, Christian; Enslin, Johannes; Wernicke, Tim; Kneissl, Michael

    2018-03-01

    An extensive analysis of the degradation characteristics of AlGaN-based ultraviolet light-emitting diodes emitting around 265 nm is presented. The optical power of LEDs stressed at a constant dc current of 100 mA (current density = 67 A/cm2 and heatsink temperature = 20 °C) decreased to about 58% of its initial value after 250 h of operation. The origin of this degradation effect has been studied using capacitance-voltage and photocurrent spectroscopy measurements conducted before and after aging. The overall device capacitance decreased, which indicates a reduction of the net charges within the space-charge region of the pn-junction during operation. In parallel, the photocurrent at excitation energies between 3.8 eV and 4.5 eV and the photocurrent induced by band-to-band absorption in the quantum barriers at 5.25 eV increased during operation. The latter effect can be explained by a reduction of the donor concentration in the active region of the device. This effect could be attributed to the compensation of donors by the activation or diffusion of acceptors, such as magnesium dopants or group-III vacancies, in the pn-junction space-charge region. The results are consistent with the observed reduction in optical power since deep level acceptors can also act as non-radiative recombination centers.

  4. Radiation induced degradation of dyes-An overview

    International Nuclear Information System (INIS)

    Rauf, M.A.; Ashraf, S. Salman

    2009-01-01

    Synthetic dyes are a major part of our life. Products ranging from clothes to leather accessories to furniture all depend on extensive use of organic dyes. An unfortunate side effect of extensive use of these chemicals is that huge amounts of these potentially carcinogenic compounds enter our water supplies. Various advanced oxidation processes (AOPs) including the use of high-energy radiation have been developed to degrade these compounds. In this review, dye decoloration and degradation as a result of its exposure to high energy radiation such as gamma radiation and pulsed electron beam are discussed in detail. The role of various transient species such as ·H, ·OH and e aq - are taken into account as reported by various researchers. Literature citations in this area show that e aq - is very effective in decolorization but is less active in the further degradation of the products formed. The degradation of the dyes is initiated exclusively by ·OH attack on electron-rich sites of the dye molecules. Additionally, various parameters that affect the efficiency of radiation induced degradation of dyes, such as effect of radiation dose, oxygen, pH, hydrogen peroxide, added ions and dye classes are also reviewed and summarized. Lastly, pilot plant application of radiation for wastewater treatment is briefly discussed.

  5. Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

    International Nuclear Information System (INIS)

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Rácz, Gergely; Takács, Erzsébet; Wojnárovits, László

    2014-01-01

    Ionizing radiation induced degradation of acetylsalicylic acid, its hydrolysis product salicylic acid and a salicylic acid derivative 5-sulpho-salicylic acid, was investigated in dilute aqueous solutions by UV–vis spectrophotometry, HPLC separation and diode-array or MS/MS detection, chemical oxygen demand, total organic carbon content and by Vibrio fischeri toxicity measurements. Hydroxyl radicals were shown to degrade these molecules readily, and first degradation products were hydroxylated derivatives in all cases. Due to the by-products, among them hydrogen peroxide, the toxicity first increased and then decreased with the absorbed dose. With prolonged irradiation complete mineralization was achieved. - Highlights: • In OH induced reactions of salicylates first products are hydroxylated derivatives. • With prolonged irradiation dihydroxy derivatives also form. • In aerated solutions the one-electron oxidant OH induces 3–4 oxidations. • Toxicity first increases and then decreases with dose mainly due to H 2 O 2 formation. • The toxicity in tap water is smaller than in pure water

  6. X-ray induced degradation of DNA in Aspergillus nidulans cells comparative analysis of UV- and X-ray induced DNA degradation

    International Nuclear Information System (INIS)

    Zinchenko, V.V.; Babykin, M.M.

    1980-01-01

    Irradiating cells of Aspergillus nidulans of the wild type in the logarythmical growth phase with X-rays leads to a certain retention in DNA synthesis. This period is characterized by an insignificant fermentative DNA degradation connected with a process of its repair. There is no direct dependence between the radiation dose and the level of DNA degradation. The investigation of X-ray induced DNA degradation in a number of UVS-mutants permits to show the existence of two branches of DNA degradation - dependent and independent of the exogenic energy source. The dependence of DNA degradation on albumen synthesis prior to irradiation and after it, is demonstrated. It is supposed that the level of X-ray induced DNA degradation is determined by two albumen systems, one of which initiates degradation and the other terminates it. The comparative analysis of UV and X-ray induced DNA degradation is carried out

  7. Construction of porous covalent organic polymer as photocatalysts for RhB degradation under visible light

    Institute of Scientific and Technical Information of China (English)

    Pingxiao Liu; Lingbao Xing; Hongtao Lin; Haining Wang; Ziyan Zhou; Zhongmin Su

    2017-01-01

    In the present work,a novel porous,and chemically stable amine-based covalent organic polymer (POP-1) was designed and synthesized under solvothermal conditions.The porosity,crystallinity,chemical stability,electrochemical properties,and diffuse reflectance of POP-1 were investigated via N2 sorption experiment,power X-ray diffraction,thermogravimetric analysis,cyclic voltammetry,and ultraviolet visible near infrared spectrometry,respectively.POP-1 exhibits good chemical stability in both acidic and alkaline aqueous solutions,as well as in organic solvents.Undoped POP-1 can be directly used as a photocatalyst for rhodamine B irradiation degradation under light-emitting diode and natural light.The Ea of POP-1 for RhB degradation is 82.37 kJ/mol.Furthermore,POP-1 can be reused as a catalyst in RhB degradation without degraded catalytic activity.

  8. A New Synergetic Nanocomposite for Dye Degradation in Dark and Light

    Science.gov (United States)

    Lakshmi Prasanna, V.; Rajagopalan, Vijayaraghavan

    2016-12-01

    Environmental hazard caused due to the release of dyes in effluents is a concern in many countries. Among the various methods to combat this problem, Advanced Oxidation Process, in which semiconductor photocatalysts are used, is considered the most effective one. These materials release Reactive Oxygen Species (ROS) such as hydroxyl radical and superoxide in suspension that degrade the dyes into non-toxic minerals. However, this process requires visible or UV light for activation. Hence, there is a need to develop materials that release ROS, both in the absence and in the presence of light, so that the efficiency of dye removal is enhanced. Towards this objective, we have designed and synthesized a new nanocomposite ZnO2/polypyrrole which releases ROS even in the dark. The ROS released in the dark and in light were estimated by standard methods. It is to be noted that ZnO2 degrades the dye only under UV light but not in dark or in the presence of visible light. We propose the mechanism of dye degradation in dark and light. The synergically coupled nanocomposite of ZnO2/ppy is the first example that degrades dyes in the dark, through advanced oxidation process without employing additional reagents.

  9. Birnessite-induced mechanochemical degradation of 2,4-dichlorophenol.

    Science.gov (United States)

    Nasser, A; Mingelgrin, U

    2014-07-01

    DCP (2,4-dichlorophenol) is the key-intermediate in the synthesis of some widely used pesticides and is an EPA priority pollutant. The mechanochemical breakdown of DCP loaded on birnessite (δ-MnO2), montmorillonite saturated with Na(+) or Cu(2+) and hematite was investigated. Mechanical force was applied by grinding of mixtures of DCP and the minerals, using mortar and pestle. Grinding of DCP for 5 min with the montmorillonites or with hematite resulted in negligible degradation during grinding, while grinding with birnessite induced the immediate degradation of 90% of the loaded DCP. Incubation for 24h after grinding did result in up to 30% degradation of the DCP loaded on the other minerals tested. HPLC and LC-MS analysis revealed that the transformation of DCP yielded oligomerization products as well as partial dechlorination. DCP degradation on birnessite was accompanied with a substantial increase in the extractability of manganese from the mineral into an acidic aqueous solution, indicating that Mn(IV) in the mineral transformed into Mn(II) and that birnessite served as an electron acceptor in the transformation. The oligomerization and partial dechlorination brought about by grinding, suggest a reduction in bioavailability and toxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Protein synthesis and degradation during starvation-induced cardiac atrophy in rabbits

    International Nuclear Information System (INIS)

    Samarel, A.M.; Parmacek, M.S.; Magid, N.M.; Decker, R.S.; Lesch, M.

    1987-01-01

    To determine the relative importance of protein degradation in the development of starvation-induced cardiac atrophy, in vivo fractional synthetic rates of total cardiac protein, myosin heavy chain, actin, light chain 1, and light chain 2 were measured in fed and fasted rabbits by continuous infusion of [ 3 H] leucine. In addition, the rate of left ventricular protein accumulation and loss were assessed in weight-matched control and fasted rabbits. Rates of total cardiac protein degradation were then estimated as the difference between rates of synthesis and growth. Fasting produced left ventricular atrophy by decreasing the rate of left ventricular protein synthesis (34.8 +/- 1.4, 27.3 +/- 3.0, and 19.3 +/- 1.2 mg/day of left ventricular protein synthesized for 0-, 3-, and 7-day fasted rabbits, respectively). Inhibition of contractile protein synthesis was evident by significant reductions in the fractional synthetic rates of all myofibrillar protein subunits. Although fractional rates of protein degradation increased significantly within 7 days of fasting, actual amounts of left ventricular protein degraded per day were unaffected. Thus, prolonged fasting profoundly inhibits the synthesis of new cardiac protein, including the major protein constituents of the myofibril. Both this inhibition in new protein synthesis as well as a smaller but significant reduction in the average half-lives of cardiac proteins are responsible for atrophy of the heart in response to fasting

  11. Solid-phase photocatalytic degradation of polystyrene plastic with goethite modified by boron under UV-vis light irradiation

    International Nuclear Information System (INIS)

    Liu Guanglong; Zhu Duanwei; Zhou Wenbing; Liao Shuijiao; Cui Jingzhen; Wu Kang; Hamilton, David

    2010-01-01

    A novel photodegradable polyethylene-boron-goethite (PE-B-goethite) composite film was prepared by embedding the boron-doped goethite into the commercial polyethylene. The goethite catalyst was modified by boron in order to improve its photocatalytic efficiency under the ultraviolet and visible light irradiation. Solid-phase photocatalytic degradation of the PE-B-goethite composite film was carried out in an ambient air at room temperature under ultraviolet and visible light irradiation. The properties of composite films were compared with those of the pure PE films and the PE-goethite composite films through performing weight loss monitoring, scanning electron microscope (SEM) analysis, FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The photo-induced degradation of PE-B-goethite composite films was higher than that of the pure PE films and the PE-goethite composite films under the UV-irradiation, while there has been little change under the visible light irradiation. The weight loss of the PE-B-goethite (0.4 wt.%) composite film reached 12.6% under the UV-irradiation for 300 h. The photocatalytic degradation mechanism of the composite films was briefly discussed.

  12. Disentangling degradation and auto-recovery of luminescence in Alq3 based organic light emitting diodes

    International Nuclear Information System (INIS)

    Rao, K. Sudheendra; Mohapatra, Y.N.

    2014-01-01

    Organic semiconductor devices and materials have matured sufficiently to be limited by intrinsic degradation processes which are as yet not understood well. We use high quality Alq 3 based organic light emitting diodes to study the rate processes involved in degradation due to electrical stressing and its auto-recovery. The method involves interspersing degradation due to electrical pulsing with variable relaxation windows to monitor time evolution of loss and recovery of luminescence. The corresponding rate processes for permanent and auto-recoverable degradation is discussed on the basis of charging and discharging of traps, and a phenomenological model based on metastability in configuration-coordinate diagram is proposed. -- Highlights: • Luminescence degradation of high quality Alq 3 based OLED device. • Auto-recovery of luminance as function of relaxation time is exponential. • Individual rates of permanent, recoverable and relaxation process measured. • A Phenomenological model based on metastable state in configuration-coordinate

  13. Homogeneous photosensitized degradation of pharmaceuticals by using red light LED as light source and methylene blue as photosensitizer

    NARCIS (Netherlands)

    Ye, Y.; Bruning, H.; Yntema, D.; Mayer, M.; Rijnaarts, H.

    2017-01-01

    Research on employing advanced oxidation processes (AOPs) for pharmaceuticals removal is gaining interests. However, detrimental effects of background water constituents in complex water matrices are limiting their implementation. In this study, we report red light induced methylene blue

  14. Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

    Directory of Open Access Journals (Sweden)

    Jamal Al-Sabahi

    2016-03-01

    Full Text Available Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

  15. STUDY OF DEGRADATION MECHANISM AND PACKAGING OF ORGANIC LIGHT EMITTING DEVICES

    Institute of Scientific and Technical Information of China (English)

    Gu Xu

    2003-01-01

    Organic Light Emitting Devices (OLED) have attracted much attention recently, for their applications in future Flat Panel Displays and lighting products. However, their fast degradation remained a major obstacle to their commercialization. Here we present a brief summary of our studies on both extrinsic and intrinsic causes for the fast degradation of OLEDs. In particular, we focus on the origin of the dark spots by "rebuilding" cathodes, which confirms that the growth of dark spots occurs primarily due to cathode delamination. In the meantime, we recapture the findings from the search for suitable OLED packaging materials, in particular polymer composites, which provide both heat dissipation and moisture resistance, in addition to electrical insulation.

  16. Radiation-induced degradation of 4-chloroaniline in aqueous solution

    International Nuclear Information System (INIS)

    Sanchez, M.; Wolfger, H.; Getoff, N.

    2002-01-01

    The radiation-induced decomposition of 4-chloroaniline (4-ClA) was studied under steady-state conditions using aqueous solutions saturated with air, pure oxygen, N 2 O, argon and argon in the presence of t-Butanol. Using HPLC-method, the initial G-values of the substrate degradation as well as of a number of radiolytic products were determined. The formation of aminophenols, chlorophenols, aniline and phenol in addition to chloride, ammonia, formaldehyde and mixture of aldehydes as well as carboxylic acids was studied as a function of absorbed dose. Based on the experimental data, probable reaction mechanisms for the degradation of 4-ClA by γ-rays and the formation of the identified products are presented

  17. Radiation-induced degradation of chlorophenols in aqueous solution

    International Nuclear Information System (INIS)

    Hu Jun; Wang Jianlong

    2005-01-01

    Radiation processing is a promising technology for applications in environmental protection, which includes wastewater treatment, micro-polluted drinking water treatment and the treatment of industrial wastewater containing various toxic and nonbiodegradable pollutants, municipal sewage and sludge disinfection, and flue gas desulfuration, etc. The paper reviews manly the recent progresses in radiolysis of chlorinated phenols in aqueous solution. Advantages and existing problems of the method in this particular application ar discussed. Mechanisms of radiation-induced degradation of chlorophenols, and the factors affecting the degradation efficiency, are discussed, too. It is concluded that combined approaches, such ozone oxidation and other methods, are of great help to the radiation processing application, in terms of lowering down the dose and increasing the efficient of pollutant removal. (authors)

  18. UV light induced photodegradation of organic dye by ZnO nanocatalysts

    International Nuclear Information System (INIS)

    Sumesh, C. K.; Patel, Bhavin; Parekh, Kinnari

    2013-01-01

    Ultraviolet light induced photocatalytic activity of ZnO nanocatalyst prepared using a wet chemical precipitation route and mineralization of the methyl orange (MO) dye has been carried out in a photocatalytic reactor. The degradation of the MO was monitored spectrophotometrically and showed a decolorization efficiency of 92% after nine hours of irradiation in the MO-ZnO/UV light system. The blue shifting of maximum peak position of the MO and the formation of extra peak at 247 nm during irradiation time advances revealed that MO degrades in the form of intermediates during the photocatalytic process.

  19. Degradation of Herbicides in the Tropical Marine Environment: Influence of Light and Sediment.

    Science.gov (United States)

    Mercurio, Philip; Mueller, Jochen F; Eaglesham, Geoff; O'Brien, Jake; Flores, Florita; Negri, Andrew P

    2016-01-01

    Widespread contamination of nearshore marine systems, including the Great Barrier Reef (GBR) lagoon, with agricultural herbicides has long been recognised. The fate of these contaminants in the marine environment is poorly understood but the detection of photosystem II (PSII) herbicides in the GBR year-round suggests very slow degradation rates. Here, we evaluated the persistence of a range of commonly detected herbicides in marine water under field-relevant concentrations and conditions. Twelve-month degradation experiments were conducted in large open tanks, under different light scenarios and in the presence and absence of natural sediments. All PSII herbicides were persistent under control conditions (dark, no sediments) with half-lives of 300 d for atrazine, 499 d diuron, 1994 d hexazinone, 1766 d tebuthiuron, while the non-PSII herbicides were less persistent at 147 d for metolachlor and 59 d for 2,4-D. The degradation of herbicides was 2-10 fold more rapid in the presence of a diurnal light cycle and coastal sediments; apart from 2,4-D which degraded more slowly in the presence of light. Despite the more rapid degradation observed for most herbicides in the presence of light and sediments, the half-lives remained > 100 d for the PS II herbicides. The effects of light and sediments on herbicide persistence were likely due to their influence on microbial community composition and its ability to utilise the herbicides as a carbon source. These results help explain the year-round presence of PSII herbicides in marine systems, including the GBR, but more research on the transport, degradation and toxicity on a wider range of pesticides and their transformation products is needed to improve their regulation in sensitive environments.

  20. Degradation of quinoline and isoquinoline by vacuum ultraviolet light and mechanism thereof

    International Nuclear Information System (INIS)

    Zhu Dazhang; Ni Yaming; Sun Dongmei; Wang Shilong; Sun Xiaoyu; Yao Side

    2010-01-01

    Since the wavelength is shorter than 190 nm, vacuum ultraviolet light has high energy enough to break the H-O bonds of water to produce HO·, as well as the protection is very easy, degradation of organic contaminants in water by vacuum ultraviolet light has obviously excellent feature of no reagent adding to the wastewater among advanced oxidation technologies. In this paper, it was reported that quinoline and isoquinoline were degraded in water by the irradiation of low-pressure quartz mercury light with the electric power of 200 W which mainly emitted the light of 185 nm and 254 nm. The change regulation of the concentration of substrates, chemical oxygen demand (COD) and total organic carbon (TOC) were investigated as well as the degradation processes of quinoline and isoquinoline were compared. It showed that both quinoline and isoquinoline could be degraded very fast under the given conditions. The concentration of the substrates decreased to nearly 0 in 10 minutes while the apparent first reaction rate constants were 0.41 ± 0.02 min -1 and 0.19 ± 0.01 min -1 , respectively. Meanwhile, the COD and TOC decreased to nearly 0 in 30 minutes. Quinoline has the faster degradation rate. In order to investigate mechanism thereof, pulse radiolysis and laser flash photolysis of quinoline and isoquinoline aqueous solution were performed, respectively. Pulse radiolysis indicated that the reaction rate constant of quinoline and HO· was faster than that of isoquinoline. In the meanwhile, laser flash photolysis indicated that both quinoline and isoquinoline could be ionized by the UV-C light while the photo-ionization efficiency of quinoline was higher than that of quinoline. These two reasons caused the faster degradation rate of quinoline. (authors)

  1. Decoupling degradation in exciton formation and recombination during lifetime testing of organic light-emitting devices

    Science.gov (United States)

    Hershey, Kyle W.; Suddard-Bangsund, John; Qian, Gang; Holmes, Russell J.

    2017-09-01

    The analysis of organic light-emitting device degradation is typically restricted to fitting the overall luminance loss as a function of time or the characterization of fully degraded devices. To develop a more complete understanding of degradation, additional specific data are needed as a function of luminance loss. The overall degradation in luminance during testing can be decoupled into a loss in emitter photoluminescence efficiency and a reduction in the exciton formation efficiency. Here, we demonstrate a method that permits separation of these component efficiencies, yielding the time evolution of two additional specific device parameters that can be used in interpreting and modeling degradation without modification to the device architecture or introduction of any additional post-degradation characterization steps. Here, devices based on the phosphor tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) are characterized as a function of initial luminance and emissive layer thickness. The overall loss in device luminance is found to originate primarily from a reduction in the exciton formation efficiency which is exacerbated in devices with thinner emissive layers. Interestingly, the contribution to overall degradation from a reduction in the efficiency of exciton recombination (i.e., photoluminescence) is unaffected by thickness, suggesting a fixed exciton recombination zone width and degradation at an interface.

  2. Neuropharmacology of light-induced locomotor activation.

    Science.gov (United States)

    Amato, Davide; Pum, Martin E; Groos, Dominik; Lauber, Andrea C; Huston, Joseph P; Carey, Robert J; de Souza Silva, Maria A; Müller, Christian P

    2015-08-01

    Presentation of non-aversive light stimuli for several seconds was found to reliably induce locomotor activation and exploratory-like activity. Light-induced locomotor activity (LIA) can be considered a convenient simple model to study sensory-motor activation. LIA was previously shown to coincide with serotonergic and dopaminergic activation in specific cortical areas in freely moving and anesthetized animals. In the present study we explore the neuropharmacology of LIA using a receptor antagonist/agonist approach in rats. The non-selective 5-HT2-receptor antagonist ritanserin (1.5-6 mg/kg, i.p.) dose-dependently reduced LIA. Selective antagonism of either the 5-HT2A-receptor by MDL 11,939 (0.1-0.4 mg/kg, i.p.), or the 5-HT2C-receptor by SDZ SER 082 (0.125-0.5 mg/kg, i.p.), alone or in combination, had no significant influence on LIA. Also the selective 5-HT1A-receptor antagonist, WAY 100635 (0.4 mg/kg, i.p.) did not affect LIA. Neither did the preferential dopamine D2-receptor antagonist, haloperidol (0.025-0.1 mg/kg, i.p.) nor the D2/D3-receptor agonist, quinpirole (0.025-0.5 mg/kg, i.p.) affect the expression of LIA. However, blocking the glutamatergic NMDA-receptor with phencyclidine (PCP, 1.5-6 mg/kg, i.p.) dose-dependently reduced LIA. This effect was also observed with ketamine (10 mg/kg, i.p.). These findings suggest that serotonin and dopamine receptors abundantly expressed in the cortex do not mediate light-stimulus triggered locomotor activity. PCP and ketamine effects, however, suggest an important role of NMDA receptors in LIA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Regime dependence of photo-darkening-induced modal degradation in high power fiber amplifier (Conference Presentation)

    Science.gov (United States)

    Boullet, Johan; Vincont, Cyril; Jolly, Alain; Pierre, Christophe

    2017-03-01

    Thermally induced transverse modal instabilities (TMI) have attracted these five years an intense research efforts of the entire fiber laser development community, as it represents the current most limiting effect of further power scaling of high power fiber laser. Anyway, since 2014, a few publications point out a new limiting thermal effect: fiber modal degradation (FMD). It is characterized by a power rollover and simultaneous increase of the cladding light at an average power far from the TMI threshold together with a degraded beam which does not exhibit temporal fluctuations, which is one of the main characteristic of TMI. We report here on the first systemic experimental study of FMD in a high power photonic crystal fiber. We put a particular emphasis on the dependence of its average power threshold on the regime of operation. We experimentally demonstrate that this dependence is intrinsically linked to regime-dependent PD-saturated losses, which are nearly three times higher in CW regime than in short pulse picosecond regime. We make the hypothesis that the existence of these different PD equilibrium states between CW regime and picosecond QCW pulsed regime is due to a partial photo-bleaching of color centers in picosecond regime thanks to a higher probability of multi-photon process induced photobleaching (PB) at high peak power. This hypothesis is corroborated by the demonstration of the reversibility of the FMD induced in CW regime by simply switching the seed CW 1064 nm light by a short pulse, picosecond oscillator.

  4. Ionizing radiation induced degradation of salicylic acid in aqueous solution

    Science.gov (United States)

    Albarrán, Guadalupe; Mendoza, Edith

    2018-06-01

    The radiation-induced degradation of salicylic acid (SA-) in aqueous solutions (1.0 and 0.1 mmol dm-3) saturated with N2O or air or without oxygen were studied. Irradiation was carried out using a cobalt-60 source. With a 1 mmol dm-3 solution saturated with N2O a seemingly total degradation occurred at about 18 kGy, although small quantities of 2,3-dihydroxybenzoic acid, catechol and 2,5-dihydroxybenzoic acid were present at that dose at concentrations of 67, 22 and 6 μmol dm-3 respectively. Under air and when free oxygen, the three radiolytic products were present at 18.54 kGy while SA- was destroyed only to 90% and 62%, respectively. In the case of 0.1 mmol dm-3 SA- solutions, the acid was degraded at 3.5 kGy if the solution contained N2O, at 5.8 kGy in air and at 7 kGy without oxygen. The concentration of the radiolytic products increased with increasing dose and after a maximum they decreased. The oxidation was followed by measuring the chemical oxygen demand; the slopes were 0.48 and 0.11, 0.21 and 0.07, 0.15 and 0.03 mmol dm-3 kGy-1 for 1.0 and 0.10 mmol dm-3 solutions saturated with N2O or air or without oxygen, respectively.

  5. Solution processable RGO-CdZnS composite for solar light responsive photocatalytic degradation of 4-Nitrophenol

    Science.gov (United States)

    Ibrahim, Sk; Chakraborty, Koushik; Pal, Tanusri; Ghosh, Surajit

    2017-05-01

    We report the one pot single step synthesis and characterization of solution processable reduced graphene oxide (RGO) - cadmium zinc sulfide (CdZnS) nanocomposite materials. The composite was characterized structurally and morphologically by XRD and TEM studies. The reduction of GO in RGO-CdZnS composite, was confirmed by XPS and Raman spectroscopy. The photocatalytic activity of the RGO-CdZnS composite was investigated towards the degradation of 4-Nitrophenol. A notable increase of photocatalytic efficiency of RGO-CdZnS compare to controlled CdZnS was observed. Here RGO plays a crucial role to efficient photo induced charge separation from the CdZnS, and decreases the electron-hole recombination probability and subsequently enhanced the photocatalytic activity of the RGO-CdZnS composite material under simulated solar light irradiation. This work highlights the potential application of RGO-based materials in the field of photocatalytic degradation of organic water pollutant.

  6. Mathematical modeling of photoinitiated coating degradation: Effects of coating glass transition temperature and light stabilizers

    DEFF Research Database (Denmark)

    Kiil, Søren; G.de With, R.A.T.M.Van Benthem

    2013-01-01

    A mathematical model, describing coating degradation mechanisms of thermoset coatings exposed to ultraviolet radiation and humidity at constant temperature, was extended to simulate the behavior of a coating with a low glass transition temperature. The effects of adding light stabilizers (a UV...

  7. Disorder-induced stiffness degradation of highly disordered porous materials

    Science.gov (United States)

    Laubie, Hadrien; Monfared, Siavash; Radjaï, Farhang; Pellenq, Roland; Ulm, Franz-Josef

    2017-09-01

    The effective mechanical behavior of multiphase solid materials is generally modeled by means of homogenization techniques that account for phase volume fractions and elastic moduli without considering the spatial distribution of the different phases. By means of extensive numerical simulations of randomly generated porous materials using the lattice element method, the role of local textural properties on the effective elastic properties of disordered porous materials is investigated and compared with different continuum micromechanics-based models. It is found that the pronounced disorder-induced stiffness degradation originates from stress concentrations around pore clusters in highly disordered porous materials. We identify a single disorder parameter, φsa, which combines a measure of the spatial disorder of pores (the clustering index, sa) with the pore volume fraction (the porosity, φ) to scale the disorder-induced stiffness degradation. Thus, we conclude that the classical continuum micromechanics models with one spherical pore phase, due to their underlying homogeneity assumption fall short of addressing the clustering effect, unless additional texture information is introduced, e.g. in form of the shift of the percolation threshold with disorder, or other functional relations between volume fractions and spatial disorder; as illustrated herein for a differential scheme model representative of a two-phase (solid-pore) composite model material.

  8. Reliability and Lifetime Prediction of Remote Phosphor Plates in Solid-State Lighting Applications Using Accelerated Degradation Testing

    NARCIS (Netherlands)

    Yazdan Mehr, M.; van Driel, W.D.; Zhang, G.Q.

    2015-01-01

    A methodology, based on accelerated degradation testing, is developed to predict the lifetime of remote phosphor plates used in solid-state lighting (SSL) applications. Both thermal stress and light intensity are used to accelerate degradation reaction in remote phosphor plates. A reliability model,

  9. Cube-like Cu2MoS4 photocatalysts for visible light-driven degradation of methyl orange

    Directory of Open Access Journals (Sweden)

    Ke Zhang

    2015-07-01

    Full Text Available Cube-like Cu2MoS4 nanoparticles with low-index facets and high crystallinity were fabricated via a hydrothermal method. The as-obtained nanocubes with an average size of 40-60 nm are composed of stacking-Cu2MoS4 layers separated by a weak Van der Waals gap of 0.5 nm. A strong absorption at visible light region is observed in the nanocube aqueous solution, indicating its optical-band gap of 1.78 eV. The photocatalytic measurements reveal that the nanocubes can thoroughly induce the degradation of methyl orange under visible light irradiation with good structural stability. Our finding may provide a way in design and fabrication of transition metal dichalcogenide nanostructures for practical applications.

  10. Reliability and corrosion induced degradation of electronic system

    International Nuclear Information System (INIS)

    Tapas, V.K.; Varde, P.V.

    2014-01-01

    This paper describe the corrosion induced degradation of electronic system failures due to environmental conditions such as humidity, temperature, ionic or organic contaminants, residuals; etc. which can accelerates as electrochemical reaction and causes corrosion of electronic components, Corrosive gases and water vapours from humid condition come into contact with the base metal results in buildup of various chemical reaction products. Ionic contamination responsible for electrochemical reaction, forms soluble complexes with metals, it can degrade the protective oxide film that forms on the positively biased metallization and/or lead to change in the local pH. Deterioration of metal components or electronic circuitry due to electrochemical migration needs to be controlled in order to reduce the corrosion. With explosive increase in demand and miniaturization in electronic system resulted in smaller components, closer spacing and thinner metallic path, it is expected that the corrosion and deterioration of electronic components may become cause or concern. This paper summarises the current understanding of chemistry behind possible causes of corrosion of electronic devices and its failure mechanism. (author)

  11. Induced oligomerization targets Golgi proteins for degradation in lysosomes.

    Science.gov (United States)

    Tewari, Ritika; Bachert, Collin; Linstedt, Adam D

    2015-12-01

    Manganese protects cells against forms of Shiga toxin by down-regulating the cycling Golgi protein GPP130. Down-regulation occurs when Mn binding causes GPP130 to oligomerize and traffic to lysosomes. To determine how GPP130 is redirected to lysosomes, we tested the role of GGA1 and clathrin, which mediate sorting in the canonical Golgi-to-lysosome pathway. GPP130 oligomerization was induced using either Mn or a self-interacting version of the FKBP domain. Inhibition of GGA1 or clathrin specifically blocked GPP130 redistribution, suggesting recognition of the aggregated GPP130 by the GGA1/clathrin-sorting complex. Unexpectedly, however, GPP130's cytoplasmic domain was not required, and redistribution also occurred after removal of GPP130 sequences needed for its normal cycling. Therefore, to test whether aggregate recognition might be a general phenomenon rather than one involving a specific GPP130 determinant, we induced homo-oligomerization of two unrelated Golgi-targeted constructs using the FKBP strategy. These were targeted to the cis- and trans-Golgi, respectively, using domains from mannosidase-1 and galactosyltransferase. Significantly, upon oligomerization, each redistributed to peripheral punctae and was degraded. This occurred in the absence of detectable UPR activation. These findings suggest the unexpected presence of quality control in the Golgi that recognizes aggregated Golgi proteins and targets them for degradation in lysosomes. © 2015 Tewari et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  12. Photocatalytic degradation of selected herbicides in aqueous suspensions of doped titania under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sojic, Daniela V., E-mail: daniela.sojic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Despotovic, Vesna N., E-mail: vesna.despotovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia); Abazovic, Nadica D., E-mail: kiki@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Comor, Mirjana I., E-mail: mirjanac@vinca.rs [Vinca Institute of Nuclear Sciences, 11001 Beograd, PO Box 522 (Serbia); Abramovic, Biljana F., E-mail: biljana.abramovic@dh.uns.ac.rs [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad (Serbia)

    2010-07-15

    The aim of this work was to study the efficiency of Fe- and N-doped titania suspensions in the photocatalytic degradation of the herbicides RS-2-(4-chloro-o-tolyloxy)propionic acid (mecoprop, MCPP), (4-chloro-2-methylphenoxy)acetic acid (MCPA), and 3,6-dichloropyridine-2-carboxylic acid (clopyralid, CP) under the visible light ({lambda} {>=} 400 nm) irradiation. The obtained results were compared with those of the corresponding undoped TiO{sub 2} (rutile/anatase) and of the most frequently used TiO{sub 2} Degussa P25. Computational modeling procedures were used to optimize geometry and molecular electrostatic potentials of MCPP, MCPA and CP and discuss the obtained results. The results indicate that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure of the compound. Lowering of the band gap of titanium dioxide by doping is not always favorable for increasing photocatalytic efficiency of degradation.

  13. Thickness-dependent photocatalytic performance of graphite oxide for degrading organic pollutants under visible light.

    Science.gov (United States)

    Oh, Junghoon; Chang, Yun Hee; Kim, Yong-Hyun; Park, Sungjin

    2016-04-28

    Photocatalysts use sustainable solar light energy to trigger various catalytic reactions. Metal-free nanomaterials have been suggested as cost-effective and environmentally friendly photocatalysts. In this work, we propose thickness-controlled graphite oxide (GO) as a metal-free photocatalyst, which is produced by exfoliating thick GO particles via stirring and sonication. All GO samples exhibit photocatalytic activity for degrading an organic pollutant, rhodamine B under visible light, and the thickest sample shows the best catalytic performance. UV-vis-NIR diffuse reflectance absorption spectra indicate that thicker GO samples absorb more vis-NIR light than thinner ones. Density-functional theory calculations show that GO has a much smaller band gap than that of single-layer graphene oxide, and thus suggest that the largely-reduced band gap is responsible for this trend of light absorption.

  14. Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

    Directory of Open Access Journals (Sweden)

    Subas K. Muduli

    2014-04-01

    Full Text Available A facile, solvothermal synthesis of mesoporous cerium oxide nanospheres is reported for the purpose of the photocatalytic degradation of organic dyes and future applications in sustainable energy research. The earth-abundant, relatively affordable, mixed valence cerium oxide sample, which consists of predominantly Ce7O12, has been characterized by powder X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy, and transmission electron microscopy. Together with N2 sorption experiments, the data confirms that the new cerium oxide material is mesoporous and absorbs visible light. The photocatalytic degradation of rhodamin B is investigated with a series of radical scavengers, suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species.

  15. Degrading emotional memories induced by a virtual reality paradigm.

    Science.gov (United States)

    Cuperus, Anne A; Laken, Maarten; van den Hout, Marcel A; Engelhard, Iris M

    2016-09-01

    In Eye Movement and Desensitization and Reprocessing (EMDR) therapy, a dual-task approach is used: patients make horizontal eye movements while they recall aversive memories. Studies showed that this reduces memory vividness and/or emotionality. A strong explanation is provided by working memory theory, which suggests that other taxing dual-tasks are also effective. Experiment 1 tested whether a visuospatial task which was carried out while participants were blindfolded taxes working memory. Experiment 2 tested whether this task degrades negative memories induced by a virtual reality (VR) paradigm. In experiment 1, participants responded to auditory cues with or without simultaneously carrying out the visuospatial task. In experiment 2, participants recalled negative memories induced by a VR paradigm. The experimental group simultaneously carried out the visuospatial task, and a control group merely recalled the memories. Changes in self-rated memory vividness and emotionality were measured. The slowing down of reaction times due to the visuospatial task indicated that its cognitive load was greater than the load of the eye movements task in previous studies. The task also led to reductions in emotionality (but not vividness) of memories induced by the VR paradigm. Weaknesses are that only males were tested in experiment 1, and the effectiveness of the VR fear/trauma induction was not assessed with ratings of mood or intrusions in experiment 2. The results suggest that the visuospatial task may be applicable in clinical settings, and the VR paradigm may provide a useful method of inducing negative memories. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Redox Active Transition Metal ions Make Melanin Susceptible to Chemical Degradation Induced by Organic Peroxide.

    Science.gov (United States)

    Zadlo, Andrzej; Pilat, Anna; Sarna, Michal; Pawlak, Anna; Sarna, Tadeusz

    2017-12-01

    With aging, retinal pigment epithelium melanosomes, by fusion with the age pigment lipofuscin, form complex granules called melanolipofuscin. Lipofuscin granules may contain oxidized proteins and lipid hydroperoxides, which in melanolipofuscin could chemically modify melanin polymer, while transition metal ions present in melanin can accelerate such oxidative modifications. The aim of this research was to examine the effect of selected transition metal ions on melanin susceptibility to chemical modification induced by the water-soluble tert-butyl hydroperoxide used as an oxidizing agent. Synthetic melanin obtained by DOPA autooxidation and melanosomes isolated from bovine retinal pigment epithelium were analyzed. To monitor tert-butyl hydroperoxide-induced oxidative changes of DMa and BMs, electron paramagnetic resonance spectroscopy, UV-vis absorption spectroscopy, dynamic light scattering, atomic force microscopy and electron paramagnetic resonance oximetry were employed. These measurements revealed that both copper and iron ions accelerated chemical degradation induced by tert-butyl hydroperoxide, while zinc ions had no effect. Strong prooxidant action was detected only in the case of melanosomes and melanin degraded in the presence of iron. It can be postulated that similar chemical processes, if they occur in situ in melanolipofuscin granules of the human retinal pigment epithelium, would modify antioxidant properties of melanin and its reactivity.

  17. Study of the degradation process of polyimide induced by high energetic ion irradiation

    International Nuclear Information System (INIS)

    Severin, Daniel

    2008-01-01

    The dissertation focuses on the radiation hardness of Kapton under extreme radiation environment conditions. To study ion-beam induced modifications, Kapton foils were irradiated at the GSI linear accelerator UNILAC using several projectiles (e.g. Ti, Mo, Au, and U) within a large fluence regime (1 x 10 10 -5 x 10 12 ions/cm 2 ). The irradiated Kapton foils were analysed by means of infrared and UV/Vis spectroscopy, tensile strength measurement, mass loss analysis, and dielectric relaxation spectroscopy. For testing the radiation stability of Kapton at the cryogenic operation temperature (5-10 K) of the superconducting magnets, additional irradiation experiments were performed at the Grand Accelerateur National d' Ions Lourds (GANIL, France) focusing on the online analysis of the outgassing process of small volatile degradation fragments. The investigations of the electrical properties analysed by dielectric relaxation spectroscopy exhibit a different trend: high fluence irradiations with light ions (e.g. Ti) lead to a slight increase of the conductivity, whereas heavy ions (e.g. Sm, Au) cause a drastic change already in the fluence regime of nonoverlapping tracks (5 x 10 10 ions/cm 2 ). Online analysis of the outgassing process during irradiation at cryogenic temperatures shows the release of a variety of small gaseous molecules (e.g. CO, CO 2 , and short hydro carbons). Also a small amount of large polymer fragments is identified. The results allow the following conclusions which are of special interest for the application of Kapton as insulating material in a high-energetic particle radiation environment. a) The material degradation measured with the optical spectroscopy and tensile strength tests are scalable with the dose deposited by the ions. The high correlation of the results allows the prediction of the mechanical degradation with the simple and non-destructive infrared spectroscopy. The degradation curve points to a critical material degradation which

  18. Study of the degradation process of polyimide induced by high energetic ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Severin, Daniel

    2008-09-19

    The dissertation focuses on the radiation hardness of Kapton under extreme radiation environment conditions. To study ion-beam induced modifications, Kapton foils were irradiated at the GSI linear accelerator UNILAC using several projectiles (e.g. Ti, Mo, Au, and U) within a large fluence regime (1 x 10{sup 10}-5 x 10{sup 12} ions/cm{sup 2}). The irradiated Kapton foils were analysed by means of infrared and UV/Vis spectroscopy, tensile strength measurement, mass loss analysis, and dielectric relaxation spectroscopy. For testing the radiation stability of Kapton at the cryogenic operation temperature (5-10 K) of the superconducting magnets, additional irradiation experiments were performed at the Grand Accelerateur National d' Ions Lourds (GANIL, France) focusing on the online analysis of the outgassing process of small volatile degradation fragments. The investigations of the electrical properties analysed by dielectric relaxation spectroscopy exhibit a different trend: high fluence irradiations with light ions (e.g. Ti) lead to a slight increase of the conductivity, whereas heavy ions (e.g. Sm, Au) cause a drastic change already in the fluence regime of nonoverlapping tracks (5 x 10{sup 10} ions/cm{sup 2}). Online analysis of the outgassing process during irradiation at cryogenic temperatures shows the release of a variety of small gaseous molecules (e.g. CO, CO{sub 2}, and short hydro carbons). Also a small amount of large polymer fragments is identified. The results allow the following conclusions which are of special interest for the application of Kapton as insulating material in a high-energetic particle radiation environment. a) The material degradation measured with the optical spectroscopy and tensile strength tests are scalable with the dose deposited by the ions. The high correlation of the results allows the prediction of the mechanical degradation with the simple and non-destructive infrared spectroscopy. The degradation curve points to a

  19. In situ Sn2+-incorporation synthesis of titanate nanotubes for photocatalytic dye degradation under visible light illumination

    International Nuclear Information System (INIS)

    Tsai, Chien-Cheng; Chen, Liang-Che; Yeh, Te-Fu; Teng, Hsisheng

    2013-01-01

    Highlights: ► Sn 2+ ions sensitize titanate nanotubes for photocatalysis under visible-light illumination. ► The Sn 5s orbital replaces the O 2p orbital as the top level of the valence band of titanates. ► The presence of Sn 2+ lifts the valence band of titanate nanotubes by approximately 0.9 eV. ► The doped Sn 2+ sites are active in donating photo-induced charges to dye degradation. - Abstract: Sn 2+ -incorporated titanate nanotubes, prepared by washing a layered sodium titanate with a SnCl 2 solution for tube formation, exhibit noticeable photocatalytic activity under visible light irradiation. This in situ synthesis results in a Sn/Ti ratio of approximately 0.6. Because of the introduction of Sn 2+ ions, the Sn 5s orbital replaces the O 2p orbital as the top level of the valence band of titanate nanotubes. Optical absorption analysis shows that Sn doping reduces the bandgap of titanate nanotubes from 3.5 to 2.6 eV. Oxidation of the Sn 2+ -incorporated titanate nanotubes leads to oxidation of Sn 2+ to Sn 4+ , hence, widening the bandgap. Under visible light irradiation, Sn 2+ -incorporated titanate nanotubes effectively degrade methylene blue in an aqueous solution, whereas the bare titanate nanotubes exhibit substantially lower photocatalytic activity. Photoluminescence analysis demonstrates that the induced charges from excitation of the Sn 2+ ions tend to be relaxed through chemical interactions, rather than irradiative recombination.

  20. Quantum control of light using electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Andre, A; Eisaman, M D; Walsworth, R L; Zibrov, A S; Lukin, M D

    2005-01-01

    We present an overview of recent theoretical and experimental work on the control of the propagation and quantum properties of light using electromagnetically induced transparency in atomic ensembles. Specifically, we discuss techniques for the generation and storage of few-photon quantum-mechanical states of light as well as novel approaches to manipulate weak pulses of light via enhanced nonlinear optical processes

  1. Model for Stress-induced Protein Degradation in Lemna minor1

    Science.gov (United States)

    Cooke, Robert J.; Roberts, Keith; Davies, David D.

    1980-01-01

    Transfer of Lemna minor fronds to adverse or stress conditions produces a large increase in the rate of protein degradation. Cycloheximide partially inhibits stress-induced protein degradation and also partially inhibits the protein degradation which occurs in the absence of stress. The increased protein degradation does not appear to be due to an increase in activity of soluble proteolytic enzymes. Biochemical evidence indicates that stress, perhaps acting via hormones, affects the permeability of certain membranes, particularly the tonoplast. A general model for stress-induced protein degradation is presented in which changes in membrane properties allow vacuolar proteolytic enzymes increased access to cytoplasmic proteins. PMID:16661588

  2. Degradation mechanism of AlInGaP light emitting diodes during PMMA encapsulation and operation

    Energy Technology Data Exchange (ETDEWEB)

    Preuss, S.

    2007-11-15

    In this thesis we investigate the degradation mechanism of AlInGaP light emitting diodes (LEDs) during encapsulation and operation. The AlInGaP LEDs are encapsulated using an injection moulding tool. The molded part acts as physical housing as well as tailors the radiation pattern. Thus a narrow light beam with a spread angle of {alpha}=10 has been observed. The LED temperature has been measured by the voltage variation of the LED which is caused by the temperature change at a constant current. Thus the thermal load of the LED chips during the encapsulation process is investigated. To verify the temperature measurement a simulation based on the finite element method has been carried out. The experimental and theoretical data are in good agreement. The LED properties are investigated before and after the encapsulation. The results are compared and we found a reduction of the serial resistance and an enhanced luminous efficiency. The peak emission energy remained constant, but a peak broadening of {delta}E=9meV has been observed. A slight polarisation of the emitted light is an indication for a polarization effect of the polymethylmethacrylat (PMMA) housing. Accelerated degradation experiments using high forward currents are performed to estimate the lifetime of the PMMA encapsulated LEDs. A diffusion model is presented to explain the decay in luminous flux versus degradation time and degradation current. We believe that the reduction of quantum efficiency is caused by p-type dopant diffusion into the active layer where it acts as a non-radiative recombination centre. Using this model we determine the lifetime under the recommended drive current of I=20mA. The resulting lifetime is t=1.5.10{sup 6}h using a reduction of 50% in the luminous flux as failure criteria. (orig.)

  3. Light-induced defect creation in hydrogenated polymorphous silicon

    International Nuclear Information System (INIS)

    Morigaki, K.; Takeda, K.; Hikita, H.; Roca i Cabarrocas, P.

    2005-01-01

    Light-induced defect creation in hydrogenated polymorphous silicon (pm-Si:H) is investigated from electron spin resonance measurements and is compared with that in hydrogenated amorphous silicon (a-Si:H). Light-induced defect creation occurs at room temperature similarly for both types of films prepared at 250 deg. C. Thermal annealing of light-induced defects is also investigated as a function of temperature. Different behaviours of annealing characteristics for pm-Si:H from those for a-Si:H are observed and discussed. In particular, we observed a decrease of the light-induced defect creation efficiency with repeated light-soaking-annealing cycles and discuss it with respect to the hydrogen bonding in pm-Si:H films

  4. Degradation of Bilayer Organic Light-Emitting Diodes Studied by Impedance Spectroscopy.

    Science.gov (United States)

    Sato, Shuri; Takata, Masashi; Takada, Makoto; Naito, Hiroyoshi

    2016-04-01

    The degradation of bilayer organic light-emitting diodes (OLEDs) with a device structure of N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (α-NPD) (hole transport layer) and tris-(8-hydroxyquinolate)aluminum (Alq3) (emissive layer and electron transport layer) has been studied by impedance spectroscopy and device simulation. Two modulus peaks are found in the modulus spectra of the OLEDs below the electroluminescence threshold. After aging of the OLEDs, the intensity of electroluminescence is degraded and the modulus peak due to the Alq3 layer is shifted to lower frequency, indicating that the resistance of the Alq3 layer is increased. Device simulation reveals that the increase in the resistance of the Alq3 layer is due to the decrease in the electron mobility in the Alq3 layer.

  5. Aging effect on radiation-induced degradation of polypropylene

    International Nuclear Information System (INIS)

    Imai, M.; Sekiguchi, M.; Tabei, M.; Yamada, Y.; Shimizu, H.

    1995-01-01

    PP sheets and films were irradiated with γ-ray and with high energy electron beam. The mechanical degradation, decay of peroxy radical and the variation of molecular weight with storage time were measured. The variation of molecular weight corresponded to mechanical degradation. The molecular weight of sheet sample at which elongation falls to zero was much higher than that of film sample. The relation between mechanical degradation and sample thickness was discussed. (author)

  6. Plasma induced degradation of benzidine in aqueous solution

    International Nuclear Information System (INIS)

    Gao Jinzhang; Gai Ke; Yang Wu; Dong Yanjie

    2003-01-01

    The degradation of benzidine in aqueous solution by the low temperature plasma was examined. The results showed that the concentration of medium and the value of pH have an appreciable effect on the degradation of benzidine. What is more important is that iron ions acting as a catalyst play an important role in this reaction. For exploring the degradation mechanism of benzidine, some of the intermediate products were recorded by HPLC (high performance liquid chromatography)

  7. Light induced electrical and macroscopic changes in hydrogenated polymorphous silicon solar cells

    Directory of Open Access Journals (Sweden)

    Roca i Cabarrocas P.

    2012-07-01

    Full Text Available We report on light-induced electrical and macroscopic changes in hydrogenated polymorphous silicon (pm-Si:H PIN solar cells. To explain the particular light-soaking behavior of such cells – namely an increase of the open circuit voltage (Voc and a rapid drop of the short circuit current density (Jsc – we correlate these effects to changes in hydrogen incorporation and structural properties in the layers of the cells. Numerous techniques such as current-voltage characteristics, infrared spectroscopy, hydrogen exodiffusion, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and spectroscopic ellipsometry are used to study the light-induced changes from microscopic to macroscopic scales (up to tens of microns. Such comprehensive use of complementary techniques lead us to suggest that light-soaking produces the diffusion of molecular hydrogen, hydrogen accumulation at p-layer/substrate interface and localized delamination of the interface. Based on these results we propose that light-induced degradation of PIN solar cells has to be addressed from not only as a material issue, but also a device point of view. In particular we bring experimental evidence that localized delamination at the interface between the p-layer and SnO2 substrate by light-induced hydrogen motion causes the rapid drop of Jsc.

  8. Degradation kinetics of aflatoxin B1 and B2 in filter paper and rough rice by using pulsed light irradiation

    Science.gov (United States)

    Rough rice is susceptible to contamination by aflatoxins, which are highly toxic, mutagenic and carcinogenic compounds. To develop aflatoxin degradation technology for rice with the use of pulsed light (PL) treatment, the objective of this study was to investigate the degradation characters of aflat...

  9. Blue light-induced oxidative stress in live skin.

    Science.gov (United States)

    Nakashima, Yuya; Ohta, Shigeo; Wolf, Alexander M

    2017-07-01

    Skin damage from exposure to sunlight induces aging-like changes in appearance and is attributed to the ultraviolet (UV) component of light. Photosensitized production of reactive oxygen species (ROS) by UVA light is widely accepted to contribute to skin damage and carcinogenesis, but visible light is thought not to do so. Using mice expressing redox-sensitive GFP to detect ROS, blue light could produce oxidative stress in live skin. Blue light induced oxidative stress preferentially in mitochondria, but green, red, far red or infrared light did not. Blue light-induced oxidative stress was also detected in cultured human keratinocytes, but the per photon efficacy was only 25% of UVA in human keratinocyte mitochondria, compared to 68% of UVA in mouse skin. Skin autofluorescence was reduced by blue light, suggesting flavins are the photosensitizer. Exposing human skin to the blue light contained in sunlight depressed flavin autofluorescence, demonstrating that the visible component of sunlight has a physiologically significant effect on human skin. The ROS produced by blue light is probably superoxide, but not singlet oxygen. These results suggest that blue light contributes to skin aging similar to UVA. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Factors influencing the thermally-induced strength degradation of B/Al composites

    Science.gov (United States)

    Dicarlo, J. A.

    1983-01-01

    Literature data related to the thermally-induced strength degradation of B/Al composites were examined in the light of fracture theories based on reaction-controlled fiber weakening. Under the assumption of a parabolic time-dependent growth for the interfacial reaction product, a Griffith-type fracture model was found to yield simple equations whose predictions were in good agreement with data for boron fiber average strength and for B/Al axial fracture strain. The only variables in these equations were the time and temperature of the thermal exposure and an empirical factor related to fiber surface smoothness prior to composite consolidation. Such variables as fiber diameter and aluminum alloy composition were found to have little influence. The basic and practical implications of the fracture model equations are discussed. Previously announced in STAR as N82-24297

  11. Factors influencing the thermally-induced strength degradation of B/Al composites

    International Nuclear Information System (INIS)

    Dicarlo, J.A.

    1983-01-01

    Literature data related to the thermally-induced strength degradation of B/Al composites were examined in the light of fracture theories based on reaction-controlled fiber weakening. Under the assumption of a parabolic time-dependent growth for the interfacial reaction product, a Griffith-type fracture model was found to yield simple equations whose predictions were in good agreement with data for boron fiber average strength and for B/Al axial fracture strain. The only variables in these equations were the time and temperature of the thermal exposure and an empirical factor related to fiber surface smoothness prior to composite consolidation. Such variables as fiber diameter and aluminum alloy composition were found to have little influence. The basic and practical implications of the fracture model equations are discussed

  12. Degradation of austenitic stainless steel (SS) light water ractor (LWR) core internals due to neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Appajosula S., E-mail: Appajosula.Rao@nrc.gov

    2014-04-01

    Austenitic stainless steels (SSs) are extensively being used in the fabrication of light water reactor (LWR) core internal components. It is because these steels have relatively high ductility, fracture toughness and moderate strength. However, the LWR internal components exposure to neutron irradiation over an extended period of plant operation degrades the materials mechanical properties such as the fracture toughness. This paper summarizes some of the results of the existing open literature data on irradiation assisted stress corrosion cracking (IASCC) of 316 CW steels that have been published by the United States Nuclear Regulatory Commission (USNRC), industry, academia, and other research agencies.

  13. Effects of light and microbial activity on the degradation of two fluoroquinolone antibiotics in pond water and sediment.

    Science.gov (United States)

    Lin, Juo-Shan; Pan, Hung-Yu; Liu, Shiu-Mei; Lai, Hong-Thih

    2010-07-01

    Enrofloxacin (ENR) and ciprofloxacin (CIP) are two fluoroquinolone (FQ) antibiotics widely used to treat diseases of human beings and cultured animals. These two FQs are usually detected in the effluent of municipal sewage plants and related aquatic environments. The purpose of this study was to understand the fates of ENR and CIP in aquaculture pond water and a sediment slurry in a laboratory-scale experiment. Effects of light and microbial activity on the degradation of these two FQs were investigated. Results indicated that natural irradiation plays a major role in the degradation of ENR and CIP in pond water and the sediment slurry. The 50 % dissipation times (DT(50)) with non-sterile treatment were 0.01 and 18.4 d for ENR, and 0.04 and 17.3 d for CIP in the water and sediment slurry, respectively. On the other hand, the degradation of ENR and CIP under dark conditions was slow or even hindered, and all of their DT(50) values exceeded 100 d. These two FQs degraded faster in the sediment slurry than in pond water under dark conditions. Artificial ultraviolet (UV) and fluorescence light had similar effects on the degradation of ENR in the pond water and sediment slurry. Degradation of CIP was faster with UV than with fluorescence light treatment, while no such difference was found for ENR degradation. CIP was a degradation product of ENR under both light and dark conditions, and DT(50) values for both compounds were shorter in the presence of light. The phenomenon of biodegradation was observed during degradation of CIP in the sediment slurry under natural light.

  14. EDITORIAL Light-induced material organization Light-induced material organization

    Science.gov (United States)

    Vainos, Nikos; Rode, Andrei V.

    2010-12-01

    Light-induced material organization extends over a broad area of research, from photon momentum transfer to atoms, molecules and particles, serving the basis for optical trapping, and expands into the laser-induced changes of material properties through photopolymerization, photodarkening, and materials ablation. Relevant phenomena are observed over many orders of magnitude of light intensity, from a few kW cm-2 for the optical trapping of living cells to 1014 W cm-2 encountered in femtosecond laser micromachining and micro-explosion. Relevant interactions reveal a rich palette of novel phenomena in the solid state, from subtle excitations and material organization to phase transformations, non-equilibrium and transient states. The laser-induced material modifications relate to changes in the crystal structure and the molecular bonding, phase transitions in liquid state, ablation and plasma production associated with extreme pressure and temperature conditions towards entirely new states of matter. The underlying physical mechanisms form the foundations for micro-engineering photonic and other functional devices and lead the way to relevant applications. At the same time, they hold the potential for creating non-equilibrium material states and a range of fundamentally new products not available by other means. The fundamental understanding of both materials nature and functional behaviour will ultimately yield novel devices and improved performance in several fields. The far reaching goals of these studies relate to the development of new methods and technologies for micro- and nano-fabrication, not only offering a significant reduction of cost, but also expanding the fabrication capabilities into unexplored areas of biophotonics and nanotechnology. This special issue of Journal of Optics presents some very recent and exciting advances in the field of materials manipulation by laser beams, aiming to underline its current trends. In optical trapping research we

  15. Radiation-induced degradation of organic pollutants in wastewater

    International Nuclear Information System (INIS)

    Bagyo, A.N.M.; Lindu, W.A.; Sadjirun, S.; Winarno, E.K.; Widayat, E.; Aryanti; Winarno, H.

    2001-01-01

    The degradation and decolouration of organic pollutants, i.e. dye stuffs and phenolic compounds, by gamma irradiation have been studied. First, samples from effluent of textile industry were taken to be irradiated at a certain condition. Irradiation was done after dissolving the samples five times with distilled water in laboratory scale, followed by upscaling those samples into 5 litre in volume. Irradiation was done at a dose of 0- 25 kGy, aerated and a dose rate of 5 kGy/h. The parameters examined were the change of absorption spectra. COD (Chemical Oxygen Demand), the percentage of the degradation, the change of pH and degradation product using HPLC. It was demonstrated that the dilution of sample enhanced the degradation and decreased the COD values. The degradation product of textile wastewater is mainly oxalic acid. Second, the effects of radiation on aerated phenolic compounds mixture, i.e. resorcinol, o-cresol and m- cresol were done. Individual phenol was studied followed by mixture of the phenolic compounds. Irradiation was done in aerated condition with doses of 0-10 kGy, dose rate of 5 kGy/h and pH range from 3 to 12. The initial concentration of resorcinol, o-cresol and w-cresol were 50 ppm and 60 ppm for phenolic compounds mixture, respectively. Parameters examined were absorption spectrum, pH, and degradation products. The uv-vis absorption of the solution were observed before and after irradiation. HPLC was used to determine the products of degradation. Degradation of resorcinol, w-cresol and o-cresol could be achieved at dose of 6 kGy at pH 9, while o-cresol in acid condition (pH 3). The degree of degradation for resorcinol, w-cresol and o-cresol at above conditions were 90%, 88% and 45%, respectively. Degradation of phenolic compound mixture occurred at a dose of 7.5 kGy and pH 9', at this condition almost 99% of phenolic compounds degraded. Oxalic acid was the main degradation product. (author)

  16. Degradation of polyethylene induced by plasma in oxidizing atmospheres

    International Nuclear Information System (INIS)

    Colin, E.; Olayo, M.G.; Cruz, G.J.

    2002-01-01

    The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

  17. Light-induced ion-acoustic instability of rarefied plasma

    International Nuclear Information System (INIS)

    Krasnov, I.V.; Sizykh, D.V.

    1987-01-01

    A new method of ion-acoustic instability excitation under the effect of coherent light, resonance to ion quantum transitions on collisionless plasma, is suggested. The light-induced ion-acoustic instability (LIIAI) considered is based on the induced progressive nonequilibrium resonance particles in the field of travelling electromagnetic wave. Principal possibility to use LIIAI in high-resolution spectroscopy and in applied problems of plasma physics, related to its instability, is pointed out

  18. Calcitonin Gene-Related Peptide Induces HIV-1 Proteasomal Degradation in Mucosal Langerhans Cells.

    Science.gov (United States)

    Bomsel, Morgane; Ganor, Yonatan

    2017-12-01

    The neuroimmune dialogue between peripheral neurons and Langerhans cells (LCs) within mucosal epithelia protects against incoming pathogens. LCs rapidly internalize human immunodeficiency virus type 1 (HIV-1) upon its sexual transmission and then trans -infect CD4 + T cells. We recently found that the neuropeptide calcitonin gene-related peptide (CGRP), secreted mucosally from peripheral neurons, inhibits LC-mediated HIV-1 trans -infection. In this study, we investigated the mechanism of CGRP-induced inhibition, focusing on HIV-1 degradation in LCs and its interplay with trans -infection. We first show that HIV-1 degradation occurs in endolysosomes in untreated LCs, and functionally blocking such degradation with lysosomotropic agents results in increased trans -infection. We demonstrate that CGRP acts via its cognate receptor and at a viral postentry step to induce faster HIV-1 degradation, but without affecting the kinetics of endolysosomal degradation. We reveal that unexpectedly, CGRP shifts HIV-1 degradation from endolysosomes toward the proteasome, providing the first evidence for functional HIV-1 proteasomal degradation in LCs. Such efficient proteasomal degradation significantly inhibits the first phase of trans -infection, and proteasomal, but not endolysosomal, inhibitors abrogate CGRP-induced inhibition. Together, our results establish that CGRP controls the HIV-1 degradation mode in LCs. The presence of endogenous CGRP within innervated mucosal tissues, especially during the sexual response, to which CGRP contributes, suggests that HIV-1 proteasomal degradation predominates in vivo Hence, proteasomal, rather than endolysosomal, HIV-1 degradation in LCs should be enhanced clinically to effectively restrict HIV-1 trans -infection. IMPORTANCE During sexual transmission, HIV-1 is internalized and degraded in LCs, the resident antigen-presenting cells in mucosal epithelia. Yet during trans -infection, infectious virions escaping degradation are transferred

  19. Light-induced vegetative anthocyanin pigmentation in Petunia

    OpenAIRE

    Albert, Nick W.; Lewis, David H.; Zhang, Huaibi; Irving, Louis J.; Jameson, Paula E.; Davies, Kevin M.

    2009-01-01

    The Lc petunia system, which displays enhanced, light-induced vegetative pigmentation, was used to investigate how high light affects anthocyanin biosynthesis, and to assess the effects of anthocyanin pigmentation upon photosynthesis. Lc petunia plants displayed intense purple anthocyanin pigmentation throughout the leaves and stems when grown under high-light conditions, yet remain acyanic when grown under shade conditions. The coloured phenotypes matched with an accumulation of anthocyanins...

  20. Light-induced reversible expansion of individual gold nanoplates

    Directory of Open Access Journals (Sweden)

    Jinsheng Lu

    2017-10-01

    Full Text Available Light-induced mechanical response of materials has been extensively investigated and widely utilized to convert light energy into mechanical energy directly. The metallic nanomaterials have excellent photothermal properties and show enormous potential in micromechanical actuators, etc. However, the photo-thermo-mechanical properties of individual metallic nanostructures have yet to be well investigated. Here, we experimentally demonstrate a way to realize light-induced reversible expansion of individual gold nanoplates on optical microfibers. The light-induced thermal expansion coefficient is obtained as 21.4 ± 4.6 ∼ 31.5 ± 4.2 μ·K-1 when the light-induced heating temperature of the gold nanoplates is 240 ∼ 490 °C. The photo-thermo-mechanical response time of the gold nanoplates is about 0.3 ± 0.1 s. This insight into the photo-thermo-mechanical properties of the gold nanoplates could deepen the understanding of the light-induced reversible expansion behavior in nanoscale and pave the way for applications based on this piezoelectric-like response, such as light-driven metallic micromotors.

  1. Degradation mechanism of polyurethane foam induced by electron beam irradiation

    International Nuclear Information System (INIS)

    Huang Wei; Fu Yibei; Bian Zhishang; He Meiying

    2002-01-01

    The degradation mechanism of irradiated polyurethane foam has been studied in detail. The changes of chemical structure and micro-phase separation have been determined by DTG. The gas products from irradiated samples are analyzed quantitatively and qualitatively by GC. The degradation mechanism of irradiated polyurethane foam has been deduced according to the experimental results. It provides some basis of the application on the polyurethane in the radiation field

  2. Enhanced visible light photocatalytic degradation of methylene blue by F-doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wei [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Liu, Xinjuan, E-mail: lxj669635@126.com [Shanghai Nanotechnlogy Promotion Center, Shanghai 200237 (China); Center for Coordination Bond and Electronic Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Li, Jinliang; Liu, Junying [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China); Zhang, Jing; Li, Ping; Chen, Chen [Shanghai Nanotechnlogy Promotion Center, Shanghai 200237 (China); Sun, Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 (China)

    2014-11-15

    Graphical abstract: F-doped TiO2 is synthesized using a modified sol–gel method for visible photocatalytic degradation of MB with a high degradation rate of 91%. - Highlights: • F-doped TiO{sub 2} are synthesized using a modified sol–gel method. • The photocatalytic degradation of methylene blue by F-doped TiO{sub 2} is investigated. • A high methylene blue degradation rate of 91% is achieved under visible light irradiation. - Abstract: F-doped TiO{sub 2} (F-TiO{sub 2}) were successfully synthesized using a modified sol–gel method. The morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, and electrochemical impedance spectra, respectively. The results show that F-TiO{sub 2} exhibits an enhanced photocatalytic performance in the degradation of MB with a maximum degradation rate of 91% under visible light irradiation as compared with pure TiO{sub 2} (32%). The excellent photocatalytic activity is due to the contribution from the increased visible light absorption, promoted separation of photo-generated electrons and holes as well as enhanced photocatalytic oxidizing species with the doping of F in TiO{sub 2}.

  3. Degradation of photovoltaic backsheet materials under multi-factor accelerated UV light exposures

    Science.gov (United States)

    Klinke, Addison G.; Gok, Abdulkerim; Ifeanyi, Silas I.; French, Roger H.; Bruckman, Laura S.

    2017-08-01

    Long term outdoor durability of photovoltaic (PV) module backsheets is critical to a module's power output over its lifetime. The use of uoropolymer-based backsheets or the addition of stabilizers to polyethylene-terephthalate (PET) and polyamide (PA) type backsheets can help extend their lifetime. This study presents the performance of 21 backsheets made of 8 different material combinations under ASTM G154 Cycle 4 accelerated light exposures. The backsheets were subjected to 4000 hours of high irradiance UVA light at a peak intensity of 1.55 W=m2 at 340 nm at 70°C with and without a condensing humidity cycle at 50°C. Backsheets were evaluated, with repeated measurements, using various evaluation techniques to identify and assess potential signs of degradation. These evaluations included the yellowness index (YI), CIE color space coordinates, and gloss at 20, 60, and 85°. The temporal evolution of the relative color change ΔE was statistically analyzed to develop a stress-response model which used the UVA light dose to predict color change. It was found that the PVF/PET/E backsheet performed the best while PET/PET/E and THV/PET/EVA backsheets performed the worst. Additionally, substantial variation in color change response, attributable to key manufacturing differences, was observed within a given material type.

  4. A highly uniform ZnO/NaTaO3 nanocomposite: Enhanced self-sensitized degradation of colored pollutants under visible light

    International Nuclear Information System (INIS)

    Xing, Guanjie; Tang, Changhe; Zhang, Bo; Zhao, Lanxiao; Su, Yiguo; Wang, Xiaojing

    2015-01-01

    In this study, a highly uniform ZnO/NaTaO 3 composite was prepared via simple hydrothermal synthesis. XRD confirmed the composite was constructed by pure cubic phase of NaTaO 3 and hexagonal phase of ZnO. SEM analysis showed that as-prepared ZnO/NaTaO 3 shaped as an irregular ginger with an obviously smaller size than that of pure ZnO without obvious agglomeration. EDS mapping demonstrated that the four elements (Na, Ta, O, Zn) in the composite were very uniformly distributed. The photocatalytic behaviors of as-prepared composites were studied in the degradation of methylene blue both under UV and visible irradiation. The bare ZnO showed the highest activity with 99.8% methylene blue (MB) photodegraded in 70 min under UV light irradiation whereas 94% photodegraded rate was achieved for ZnO/NaTaO 3 . More importantly, the uniform composite of ZnO/NaTaO 3 exhibited effective degradation of methylene blue under visible light which can be attributed to the well dyes adsorption abilities and the high efficiency of electron separation, induced by the synergistic effect between ZnO and NaTaO 3 . It is confirmed the dye rather than a semiconductor is excited under visible light irradiation and a self-sensitized photocatalytic mechanism was then proposed based on the experimental results. - Graphical abstract: Visible light photocatalytic activity of ZnO/NaTaO 3 and proposed schematic of self-sensitization directed photogradation of MB. - Highlights: • Highly uniform ZnO/NaTaO 3 photocatalysts were fabricated by hydrothermal method. • ZnO/NaTaO 3 composite exhibited effective degradation of MB under visible light. • ZnO/NaTaO 3 composite effectively promoted dye adsorption and electrons separation. • A self-sensitized photocatalytic mechanism was proposed for the degradation of dye

  5. Chemically Induced Degradation of the Oncogenic Transcription Factor BCL6

    Directory of Open Access Journals (Sweden)

    Nina Kerres

    2017-09-01

    Full Text Available The transcription factor BCL6 is a known driver of oncogenesis in lymphoid malignancies, including diffuse large B cell lymphoma (DLBCL. Disruption of its interaction with transcriptional repressors interferes with the oncogenic effects of BCL6. We used a structure-based drug design to develop highly potent compounds that block this interaction. A subset of these inhibitors also causes rapid ubiquitylation and degradation of BCL6 in cells. These compounds display significantly stronger induction of expression of BCL6-repressed genes and anti-proliferative effects than compounds that merely inhibit co-repressor interactions. This work establishes the BTB domain as a highly druggable structure, paving the way for the use of other members of this protein family as drug targets. The magnitude of effects elicited by this class of BCL6-degrading compounds exceeds that of our equipotent non-degrading inhibitors, suggesting opportunities for the development of BCL6-based lymphoma therapeutics.

  6. A light-induced shortcut in the planktonic microbial loop

    Science.gov (United States)

    Ptacnik, Robert; Gomes, Ana; Royer, Sarah-Jeanne; Berger, Stella A.; Calbet, Albert; Nejstgaard, Jens C.; Gasol, Josep M.; Isari, Stamatina; Moorthi, Stefanie D.; Ptacnikova, Radka; Striebel, Maren; Sazhin, Andrey F.; Tsagaraki, Tatiana M.; Zervoudaki, Soultana; Altoja, Kristi; Dimitriou, Panagiotis D.; Laas, Peeter; Gazihan, Ayse; Martínez, Rodrigo A.; Schabhüttl, Stefanie; Santi, Ioulia; Sousoni, Despoina; Pitta, Paraskevi

    2016-07-01

    Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

  7. A light-induced shortcut in the planktonic microbial loop

    KAUST Repository

    Ptacnik, Robert

    2016-07-11

    Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

  8. A light-induced shortcut in the planktonic microbial loop

    KAUST Repository

    Ptacnik, Robert; Gomes, Ana; Royer, Sarah-Jeanne; Berger, Stella A.; Calbet, Albert; Nejstgaard, Jens C.; Gasol, Josep M.; Isari, Stamatina; Moorthi, Stefanie D.; Ptacnikova, Radka; Striebel, Maren; Sazhin, Andrey F.; Tsagaraki, Tatiana M.; Zervoudaki, Soultana; Altoja, Kristi; Dimitriou, Panagiotis D.; Laas, Peeter; Gazihan, Ayse; Martí nez, Rodrigo A.; Schabhü ttl, Stefanie; Santi, Ioulia; Sousoni, Despoina; Pitta, Paraskevi

    2016-01-01

    Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

  9. Targeting Neutrophil Protease-Mediated Degradation of Tsp-1 to Induce Metastatic Dormancy

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-16-1-0615 TITLE: Targeting Neutrophil Protease-Mediated Degradation of Tsp-1 to Induce Metastatic Dormancy PRINCIPAL...29 Sep 2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Targeting Neutrophil Protease-Mediated Degradation of Tsp-1 to Induce Metastatic Dormancy...infection or cigarette smoke enhanced pulmonary metastasis from breast cancer in humans and mice. Similarly, autoimmune arthritis, characterized by

  10. Temperature Induced Degradation of Nb Ti/Cu Composite Superconductors

    CERN Document Server

    Scheuerlein, C; Senatore, C; Di Michiel, M; Thilly, L; Gerardin, A; Reluner, B; Oberli, L; Willering, G; Bottura, L

    2009-01-01

    The degradation mechanisms of state-of-the-art Nb-Ti/Cu superconductors are described, based on in-situ synchrotron X-ray diffraction measurements during heat treatment. A quantitative description of the Nb-Ti/Cu degradation in terms of critical current density, Cu stabiliser resistivity and mechanical composite strength is presented. In an applied magnetic field a significant critical current degradation is already observed after a 5-minute 400 °C heat treatment, due to variations of a-Ti precipitate size and distribution within the Nb-Ti alloy filaments. A strong degradation of the strand mechanical properties is observed after several minutes heating above 550 °C, which is also the temperature at which the formation of Cu Ti intermetallic phases is detected. Several minutes heating at 250 °C are sufficient to increase the RRR of the strongly cold work strands inside a Rutherford type cable from about 80 to about 240. Heating for several minutes at 400 °C does not cause a significant conductor degradati...

  11. Radiation induced degradation of xanthan gum in aqueous solution

    Science.gov (United States)

    Hayrabolulu, Hande; Demeter, Maria; Cutrubinis, Mihalis; Güven, Olgun; Şen, Murat

    2018-03-01

    In our previous study, we have investigated the effect of gamma rays on xanthan gum in the solid state and it was determined that dose rate was an important factor effecting the radiation degradation of xanthan gum. In the present study, in order to provide a better understanding of how ionizing radiation effect xanthan gum, we have investigated the effects of ionizing radiation on aqueous solutions of xanthan at various concentrations (0.5-4%). Xanthan solutions were irradiated with gamma rays in air, at ambient temperature, at different dose rates (0.1-3.3-7.0 kGy/h) and doses (2.5-50 kGy). Change in their molecular weights was followed by size exclusion chromatography (SEC). Chain scission yield (G(S)), and degradation rate constants (k) were calculated. It was determined that, solution concentration was a factor effecting the degradation chemical yield and degradation rate of xanthan gum. Chain scission reactions were more effective for lower solution concentrations.

  12. Morphological effect of BiVO4 catalysts on degradation of aqueous paracetamol under visible light irradiation.

    Science.gov (United States)

    Hu, Changying; Xu, Jie; Zhu, Yaqi; Chen, Acong; Bian, Zhaoyong; Wang, Hui

    2016-09-01

    Morphological effect of bismuth vanadate (BiVO4) on visible light-driven catalytic degradation of aqueous paracetamol was carefully investigated using four monoclinic BiVO4 catalysts. The catalysts with different morphologies were controllably prepared by a hydrothermal method without any additions. The prepared catalysts were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy (DRS). Under the visible light irradiation, these catalysts with different morphology were investigated to degrade aqueous paracetamol contaminant. The degradation effects were evaluated based on the catalyst morphology, solution pH, initial paracetamol concentration, and catalyst dosage. Cube-like BiVO4 powders exhibited excellent photocatalytic performance. The optimal photocatalytic performance of the cube-like BiVO4 in degrading paracetamol was achieved.

  13. Degradation of organic compounds by the combined action of light and microorganisms

    International Nuclear Information System (INIS)

    Amador, J.A.

    1990-01-01

    The degradation of organic compounds bound to soil humic acid and of pyridinedicarboxylic acids by the combined action of light and microorganisms was studied. The rate and extent of microbial mineralization of [2 14 C]glycine/humic acid complexes in the dark increased inversely with molecular weight of the molecules. Sunlight irradiation of [ 14 C] glycine/humic acid complexes resulted in loss of UV-light absorbance and an increase in the yield of 14 C-labeled low-molecular weight products. The rate and extent of microbial mineralization were also enhanced by the initial photolysis of the complexes. Greater than half of the radioactivity in the low-molecular-weight photoproducts appeared to be associated with carboxylic acids. Microbial mineralization of the organic carbon increased with integrated solar flux and with the loss of absorbance at 330 nm. Mineralization increased with the percentage of the original complex that was converted to low-molecular weight photoproducts. Only light at wavelengths below 380 nm had an effect on the molecular-weight distribution of the products formed from the glycine/humic acid complexes and on the subsequent microbial mineralization. Irradiation of [U 14 C]aniline/humic acid and of [U- 14 C]phenol/humic acid complexes in sunlight resulted in a loss of UV-light absorbance and an increase in the yield of C-labeled low molecular-weight products. Sunlight irradiation of the [ 14 C]aniline/humic acid complexes had no effect on their subsequent mineralization, but sunlight irradiation enhanced the rate and extent of mineralization of the [ 14 C]phenol/humic acid complexes. The mineralization of phenol/humic acid complexes increased with integrated solar flux and was proportional to the percentage of the original complex that was converted to low-molecular-weight photoproducts

  14. Efficient degradation of Methylene Blue dye over highly reactive Cu doped strontium titanate (SrTiO3) nanoparticles photocatalyst under visible light.

    Science.gov (United States)

    Rahman, Qazi Inamur; Ahmad, Musheer; Misra, Sunil Kumar; Lohani, Minaxi

    2012-09-01

    Visible light induced photocatalysts of Cu doped SrTiO3 (Cu/SrTiO3) nanoparticles with the size -60-75 nm were prepared via facile sol-gel method. The morphological, optical, crystalline properties and compositions of synthesized Cu/SrTiO3 nanoparticles were thoroughly characterized by field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), ultra violet-visible spectroscopy (UV-Vis) and energy dispersive X-ray (EDX). A significant red shift in the UV-diffused reflectance spectrum was observed and the absorption edge shifted to visible region by the Cu doping. Surprisingly, the band gap of SrTiO3 was changed from 3.2 eV drop to 2.96 eV. The photocatalytic activity of the synthesized Cu/SrTiO3 nanoparticles was demonstrated for the degradation of Methylene Blue dye under visible light irradiation. The formation of new acceptor region in Cu/SrTiO3 was responsible for high photocatalytic activity of Cu/SrTiO3 nanoparticles. The results showed that the Methylene Blue dye was degraded by -66% within time span of 2 h over the Cu/SrTiO3 nanoparticles. This dye degradation reaction followed the Langmuir-Hinshelwood kinetics and also exhibited first order reaction rate. The calculated rate constant for the degradation reaction following first order kinetics was k = 0.0016 min(-1).

  15. Enhancement of tributyltin degradation under natural light by N-doped TiO2 photocatalyst

    International Nuclear Information System (INIS)

    Bangkedphol, S.; Keenan, H.E.; Davidson, C.M.; Sakultantimetha, A.; Sirisaksoontorn, W.; Songsasen, A.

    2010-01-01

    Photo-degradation of tributyltin (TBT) has been enhanced by TiO 2 nanoparticles doped with nitrogen (N-doped TiO 2 ). The N-doped catalyst was prepared by a sol-gel reaction of titanium (IV) tetraisopropoxide with 25% ammonia solution and calcined at various temperatures from 300 to 600 deg. C. X-ray diffraction results showed that N-doped TiO 2 remained amorphous at 300 deg. C. At 400 deg. C the anatase phase occurred then transformed to the rutile phase at 600 deg. C. The crystallite size calculated from Scherrer's equation was in the range of 16-51 nm which depended on the calcination temperature. N-doped TiO 2 calcined at 400 deg. C which contained 0.054% nitrogen, demonstrated the highest photocatalytic degradation of TBT at 28% in 3 h under natural light when compared with undoped TiO 2 and commercial photocatalyst, P25-TiO 2 which gave 14.8 and 18% conversion, respectively.

  16. Visible light assisted photoelectrocatalytic degradation of sugarcane factory wastewater by sprayed CZTS thin films

    Science.gov (United States)

    Hunge, Y. M.; Mahadik, M. A.; Patil, V. L.; Pawar, A. R.; Gadakh, S. R.; Moholkar, A. V.; Patil, P. S.; Bhosale, C. H.

    2017-12-01

    Highly crystalline Cu2ZnSnS4 (CZTS) thin films have been deposited onto glass and FTO coated glass substrates by simple chemical spray-pyrolysis technique. It is an important material for solar energy conversion through the both photovoltaics and photocatalysis. The effect of substrate temperatures on the physico-chemical properties of the CZTS films is studied. The XRD study shows the formation of single phase CZTS with kesterite structure. FE-SEM analysis reveals nano flakes architecture with pin-hole and crake free surface with more adherent. The film deposited at optimized substrate temperature exhibits optical band gap energy of 1.90 eV, which lies in the visible region of the solar spectrum and useful for photocatalysis application. The photoelectrocatalytic activities of the large surface area (10 × 10 cm2) deposited CZTS thin film photocatalysts were evaluated for the degradation of sugarcane factory wastewater under visible light irradiation. The results show that the CZTS thin film photocatalyst exhibited about 90% degradation of sugar cane factory wastewater. The mineralization of sugarcane factory wastewater is studied by measuring chemical oxygen demand (COD) values.

  17. Bi2WO6 nanoflowers: An efficient visible light photocatalytic activity for ceftriaxone sodium degradation

    Science.gov (United States)

    Zhao, Yanyan; Wang, Yongbo; Liu, Enzhou; Fan, Jun; Hu, Xiaoyun

    2018-04-01

    The morphology-controlled synthesis of nano-structure photocatalyst have leaded a new possibility to improve their physical and chemical properties. Herein, Bi2WO6 nanocrystals (BWO) with nano-flower, nano plates, knot shape, rod like and irregular morphologies have been successfully synthesized through a highly facile hydrothermal process by simply adjusting pH values, reactive solvents and temperature. Photocatalytic activity of the as-prepared samples were evaluated by degradation of Ceftriaxone sodium under visible light irradiation (λ > 420 nm), the results indicated that all the BWO samples exhibit morphology-associated photocatalytic activity, and the 3D flowerlike-structure of BWO composed of well-ordered nano plates (BWO-D-5) displayed the outstanding photocatalytic activity. Through getting insight into the mechanism, h+ and rad O2- play major roles compared with rad OH in photocatalytic degradation process. The possible pathway of Ceftriaxone sodium and the intermediates were proposed to better understand the reaction process. Moreover, this work not only provides an example of morphology-dependent photocatalytic activity of BWO but also provides an illustrative example for removing organic pollutant molecules according to practical requirements.

  18. Negative charge induced degradation of PMOSFETs with BF2-implanted p+-poly gate

    International Nuclear Information System (INIS)

    Lu, C.Y.; Sung, J.M.

    1989-01-01

    A new degradation phenomenon on thin gate oxide PMOS-FETs with BF 2 implanted p + -poly gate has been demonstrated and investigated. The cause of this type of degradation is a combination of the boron penetration through the gate oxide and charge trap generation due to the presence of fluorine in the gate oxide and some other processing-induced effects. The negative charge-induced degradation other than enhanced boron diffusion has been studied in detail here. The impact of this process-sensitive p + -poly gate structure on deep submicron CMOS process integration has been discussed. (author)

  19. Solar ultraviolet irradiation induces decorin degradation in human skin likely via neutrophil elastase.

    Science.gov (United States)

    Li, Yong; Xia, Wei; Liu, Ying; Remmer, Henriette A; Voorhees, John; Fisher, Gary J

    2013-01-01

    Exposure of human skin to solar ultraviolet (UV) irradiation induces matrix metalloproteinase-1 (MMP-1) activity, which degrades type I collagen fibrils. Type I collagen is the most abundant protein in skin and constitutes the majority of skin connective tissue (dermis). Degradation of collagen fibrils impairs the structure and function of skin that characterize skin aging. Decorin is the predominant proteoglycan in human dermis. In model systems, decorin binds to and protects type I collagen fibrils from proteolytic degradation by enzymes such as MMP-1. Little is known regarding alterations of decorin in response to UV irradiation. We found that solar-simulated UV irradiation of human skin in vivo stimulated substantial decorin degradation, with kinetics similar to infiltration of polymorphonuclear (PMN) cells. Proteases that were released from isolated PMN cells degraded decorin in vitro. A highly selective inhibitor of neutrophil elastase blocked decorin breakdown by proteases released from PMN cells. Furthermore, purified neutrophil elastase cleaved decorin in vitro and generated fragments with similar molecular weights as those resulting from protease activity released from PMN cells, and as observed in UV-irradiated human skin. Cleavage of decorin by neutrophil elastase significantly augmented fragmentation of type I collagen fibrils by MMP-1. Taken together, these data indicate that PMN cell proteases, especially neutrophil elastase, degrade decorin, and this degradation renders collagen fibrils more susceptible to MMP-1 cleavage. These data identify decorin degradation and neutrophil elastase as potential therapeutic targets for mitigating sun exposure-induced collagen fibril degradation in human skin.

  20. Photocatalytic degradation of p,p'-DDT under UV and visible light using interstitial N-doped TiO₂.

    Science.gov (United States)

    Ananpattarachai, Jirapat; Kajitvichyanukul, Puangrat

    2015-01-01

    1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p'-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO2 in degradation and mineralization of the p,p'-DDT under UV and visible light in aqueous solution. The N-doped TiO2 nanopowders were prepared by a simple modified sol-gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p'-DDT using the synthesized N-doped TiO2 under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p'-DDT degradation performance of the N-doped TiO2 were evaluated. Results show that the N-doped TiO2 can degrade p,p'-DDT effectively under both UV and visible lights. The rate constant of the p,p'-DDT degradation under UV light was only 0.0121 min(-1), whereas the rate constant of the p,p'-DDT degradation under visible light was 0.1282 min(-1). Under visible light, the 100% degradation of p,p'-DDT were obtained from N-doped TiO2 catalyst. The reaction rate of p,p'-DDT degradation using N-doped TiO2 under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO2 under visible light was 0.03078 L mg(-1), and the apparent reaction rate constant (k) was 1.3941 mg L(-1)-min. Major intermediates detected during the p,p'-DDT degradation were p,p'-DDE, o,p'-DDE, p,p'-DDD and p,p'-DDD. Results from this work can be applied further for the breakdown of p,p'-DDT molecule in the real contaminated water using this technology.

  1. Synthesis, Characterization, and Evaluation of Boron-Doped Iron Oxides for the Photocatalytic Degradation of Atrazine under Visible Light

    Directory of Open Access Journals (Sweden)

    Shan Hu

    2012-01-01

    Full Text Available Photocatalytic degradation of atrazine by boron-doped iron oxides under visible light irradiation was investigated. In this work, boron-doped goethite and hematite were successfully prepared by sol-gel method with trimethylborate as boron precursor. The powders were characterized by XRD, UV-vis diffuse reflectance spectra, and porosimetry analysis. The results showed that boron doping could influence the crystal structure, enlarge the BET surface area, improve light absorption ability, and narrow their band-gap energy. The photocatalytic activity of B-doped iron oxides was evaluated in the degradation of atrazine under the visible light irradiation, and B-doped iron oxides showed higher atrazine degradation rate than that of pristine iron oxides. Particularly, B-doped goethite exhibited better photocatalytic activity than B-doped hematite.

  2. Evaluation of mechano-chemical degradation induced stresses of polyolefin pipes

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Byoung Ho [Korea Univ., Seoul (Korea, Republic of); Chudnovsky, Alexander [The University of Illinois, Chicago (United States)

    2008-07-01

    The fracture phenomena in engineering thermoplastics resulting from chemical degradation is usually observed in the form of a microcrack network within a surface layer of degraded polymer exposed to a combined action of mechanical stresses and chemically aggressive environment. Degradation of polymers is usually manifested in a reduction of molecular weight, increase of crystallinity in semi crystalline polymers, increase of material density, a subtle increase in yield strength, and a dramatic reduction in toughness. The critical level of degradation for fracture initiation depends on the rates of toughness deterioration and build-up of the degradation related stresses as well as on the manufacturing and service stresses. In this paper, the evaluation of mechano-chemical degradation induced stress is attempted, and the application of the evaluated stress to the fracture initiation of polymer pipes is presented.

  3. Evaluation of mechano-chemical degradation induced stresses of polyolefin pipes

    International Nuclear Information System (INIS)

    Choi, Byoung Ho; Chudnovsky, Alexander

    2008-01-01

    The fracture phenomena in engineering thermoplastics resulting from chemical degradation is usually observed in the form of a microcrack network within a surface layer of degraded polymer exposed to a combined action of mechanical stresses and chemically aggressive environment. Degradation of polymers is usually manifested in a reduction of molecular weight, increase of crystallinity in semi crystalline polymers, increase of material density, a subtle increase in yield strength, and a dramatic reduction in toughness. The critical level of degradation for fracture initiation depends on the rates of toughness deterioration and build-up of the degradation related stresses as well as on the manufacturing and service stresses. In this paper, the evaluation of mechano-chemical degradation induced stress is attempted, and the application of the evaluated stress to the fracture initiation of polymer pipes is presented

  4. Device Engineering and Degradation Mechanism Study of All-Phosphorescent White Organic Light-Emitting Diodes

    Science.gov (United States)

    Xu, Lisong

    As a possible next-generation solid-state lighting source, white organic light-emitting diodes (WOLEDs) have the advantages in high power efficiency, large area and flat panel form factor applications. Phosphorescent emitters and multiple emitting layer structures are typically used in high efficiency WOLEDs. However due to the complexity of the device structure comprising a stack of multiple layers of organic thin films, ten or more organic materials are usually required, and each of the layers in the stack has to be optimized to produce the desired electrical and optical functions such that collectively a WOLED of the highest possible efficiency can be achieved. Moreover, device degradation mechanisms are still unclear for most OLED systems, especially blue phosphorescent OLEDs. Such challenges require a deep understanding of the device operating principles and materials/device degradation mechanisms. This thesis will focus on achieving high-efficiency and color-stable all-phosphorescent WOLEDs through optimization of the device structures and material compositions. The operating principles and the degradation mechanisms specific to all-phosphorescent WOLED will be studied. First, we investigated a WOLED where a blue emitter was based on a doped mix-host system with the archetypal bis(4,6-difluorophenyl-pyridinato-N,C2) picolinate iridium(III), FIrpic, as the blue dopant. In forming the WOLED, the red and green components were incorporated in a single layer adjacent to the blue layer. The WOLED efficiency and color were optimized through variations of the mixed-host compositions to control the electron-hole recombination zone and the dopant concentrations of the green-red layers to achieve a balanced white emission. Second, a WOLED structure with two separate blue layers and an ultra-thin red and green co-doped layer was studied. Through a systematic investigation of the placement of the co-doped red and green layer between the blue layers and the material

  5. Doping effect on monolayer MoS2 for visible light dye degradation - A DFT study

    Science.gov (United States)

    Cheriyan, Silpa; Balamurgan, D.; Sriram, S.

    2018-04-01

    The electronic and optical properties of, Nitrogen (N), Cobalt (Co), and Co-N co-doped monolayers of MoS2 has been studied by using density functional theory (DFT) for visible light photocatalytic activity. From the calculations, it has been observed that the band gap of monolayer MoS2 has been reduced while doping. However, the band gaps of pristine and N doped MoS2 monolayers only falls in the visible region while for Co and Co-N co-doped systems, the band gap shifted to IR region. The optical calculation also confirms the results. The formation energy values of the doped system reaveal that MoS2 monolayer drops its stability while doping. To evaluate the photocatalytic response, band edge potentials of pristine and N-MoS2 are calculated, and the observed results show that compared to N-doped MoS2 monolayer, pure MoS2 is highly suitable for visible light photocatalytic dye degradation.

  6. Light-induced vegetative anthocyanin pigmentation in Petunia

    Science.gov (United States)

    Albert, Nick W.; Lewis, David H.; Zhang, Huaibi; Irving, Louis J.; Jameson, Paula E.; Davies, Kevin M.

    2009-01-01

    The Lc petunia system, which displays enhanced, light-induced vegetative pigmentation, was used to investigate how high light affects anthocyanin biosynthesis, and to assess the effects of anthocyanin pigmentation upon photosynthesis. Lc petunia plants displayed intense purple anthocyanin pigmentation throughout the leaves and stems when grown under high-light conditions, yet remain acyanic when grown under shade conditions. The coloured phenotypes matched with an accumulation of anthocyanins and flavonols, as well as the activation of the early and late flavonoid biosynthetic genes required for flavonol and anthocyanin production. Pigmentation in Lc petunia only occurred under conditions which normally induce a modest amount of anthocyanin to accumulate in wild-type Mitchell petunia [Petunia axillaris×(Petunia axillaris×Petunia hybrida cv. ‘Rose of Heaven’)]. Anthocyanin pigmentation in Lc petunia leaves appears to screen underlying photosynthetic tissues, increasing light saturation and light compensation points, without reducing the maximal photosynthetic assimilation rate (Amax). In the Lc petunia system, where the bHLH factor Leaf colour is constitutively expressed, expression of the bHLH (Lc) and WD40 (An11) components of the anthocyanin regulatory system were not limited, suggesting that the high-light-induced anthocyanin pigmentation is regulated by endogenous MYB transcription factors. PMID:19380423

  7. Chromatic assimilation unaffected by perceived depth of inducing light.

    Science.gov (United States)

    Shevell, Steven K; Cao, Dingcai

    2004-01-01

    Chromatic assimilation is a shift toward the color of nearby light. Several studies conclude that a neural process contributes to assimilation but the neural locus remains in question. Some studies posit a peripheral process, such as retinal receptive-field organization, while others claim the neural mechanism follows depth perception, figure/ground segregation, or perceptual grouping. The experiments here tested whether assimilation depends on a neural process that follows stereoscopic depth perception. By introducing binocular disparity, the test field judged in color was made to appear in a different depth plane than the light that induced assimilation. The chromaticity and spatial frequency of the inducing light, and the chromaticity of the test light, were varied. Chromatic assimilation was found with all inducing-light sizes and chromaticities, but the magnitude of assimilation did not depend on the perceived relative depth planes of the test and inducing fields. We found no evidence to support the view that chromatic assimilation depends on a neural process that follows binocular combination of the two eyes' signals.

  8. Surface photo-discoloration and degradation of dyed wood veneer exposed to different wavelengths of artificial light

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States); Shao, Lingmin [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Gao, Jianmin, E-mail: jmgao@bjfu.edu.cn [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Guo, Hongwu, E-mail: hwg5052@163.com [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Chen, Yao [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Cheng, Qingzheng; Via, Brian K. [Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States)

    2015-03-15

    Highlights: • Investigate the selective absorption of different wavelengths of UV–vis light by dyed wood chromophores. • Identify connection between light wavelengths and surface color changes and chemical structure degradation. • Study hypochromic effect based on surface reflectance and K/S absorption changes during UV–vis irradiation. - Abstract: The surface of dyed wood is prone to discoloration when exposed to light irradiation which significantly decreases its decorative effect and shortens its service life. The influence of light wavelength exposure to the surface of dyed wood was investigated to study the effect on discoloration and degradation. Acid Blue V and Acid Red GR dyed wood veneers were subjected to light exposure with different wavelengths from the UV to visible region (254–420 nm). Results showed that the surface discoloration of dyed wood was linearly related to lignin concentration and dyes degradation and the consequent transformation of chromophoric groups such as aromatic (C=C) and carbonyl (C=O) through methoxy reaction. The dyes, lignin and some active constituents were degraded severely, even at short exposures. Acid Blue V dyed wood exhibited greater discoloration than the Acid Red GR treatment. The reflectance and K/S absorption curve showed a hypochromic effect on the dyed wood surface. The dyes and wood chemical structure played a complex and combined role on the selective absorption of different wavelengths of light. The color change rate was apparent with 254 nm exposure in the initial stages, but a greater discoloration rate occurred on the samples irradiated at 313 and 340 nm than at 254 and 420 nm with the time prolonged. The degradation rate and degree of discoloration correlated well with the light energy and wavelength.

  9. Electrical and Photo-Induced Degradation of ZnO Layers in Organic Photovoltaics

    DEFF Research Database (Denmark)

    Manor, Assaf; Katz, Eugene A.; Tromholt, Thomas

    2011-01-01

    minutes) does not affect the short-circuit current of the device. However, a significant degradation of V-OC and FF has been recorded by measurements of the cell current-voltage curves with a variation of light intensity, for the devices before and after the treatment. The same degradation was found......We present the case of degradation of organic solar cells by sunlight concentrated to a moderate level (similar to 4 suns). This concentration level is not enough for sufficient acceleration of the photobleaching or trap-generation in the photoactive layer and therefore such short treatment (100...

  10. Tributyltin induces mitochondrial fission through Mfn1 degradation in human induced pluripotent stem cells.

    Science.gov (United States)

    Yamada, Shigeru; Asanagi, Miki; Hirata, Naoya; Itagaki, Hiroshi; Sekino, Yuko; Kanda, Yasunari

    2016-08-01

    Organotin compounds, such as tributyltin (TBT), are well-known endocrine disruptors. TBT is also known to cause various forms of cytotoxicity, including neurotoxicity and immunotoxicity. However, TBT toxicity has not been identified in normal stem cells. In the present study, we examined the effects of TBT on cell growth in human induced pluripotent stem cells (iPSCs). We found that exposure to nanomolar concentrations of TBT decreased intracellular ATP levels and inhibited cell viability in iPSCs. Because TBT suppressed energy production, which is a critical function of the mitochondria, we further assessed the effects of TBT on mitochondrial dynamics. Staining with MitoTracker revealed that nanomolar concentrations of TBT induced mitochondrial fragmentation. TBT also reduced the expression of mitochondrial fusion protein mitofusin 1 (Mfn1), and this effect was abolished by knockdown of the E3 ubiquitin ligase membrane-associated RING-CH 5 (MARCH5), suggesting that nanomolar concentrations of TBT could induce mitochondrial dysfunction via MARCH5-mediated Mfn1 degradation in iPSCs. Thus, mitochondrial function in normal stem cells could be used to assess cytotoxicity associated with metal exposure. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. HD domain of SAMHD1 influences Vpx-induced degradation at a post-interaction step

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jian; Hou, Jingwei; Zhao, Ke; Yu, Xiao-Fang; Du, Juan, E-mail: jdu@jlu.edu.cn

    2016-02-12

    Primate SAMHD1 proteins are potent inhibitors of viruses, including retroviruses such as HIV-1, HIV-2, and SIV. Vpx, a distinctive viral protein expressed by HIV-2 and some SIVs, induces SAMHD1 degradation by forming a Vpx-DCAF1-based ubiquitin ligase complex. Either the N- or the C-terminus of SAMHD1 is critical for Vpx-induced degradation, depending on the types of SAMHD1 and Vpx proteins. However, it was not fully understood whether other regions of SAMHD1 also contribute to its depletion by Vpx. In the present study, we report that SAMHD1 from chicken (SAMHD1{sub GG}) was not degraded by SIVmac Vpx, in contrast with results for human SAMHD1 (SAMHD1{sub HS}). Results regarding to SAMHD1{sub HS} and SAMHD1{sub GG} fusion proteins supported previous findings that the C-terminus of SAMHD1{sub HS} is essential for Vpx-induced degradation. Internal domain substitution, however, revealed that the HD domain also contributes to Vpx-mediated SAMHD1 degradation. Interestingly, the HD domain influenced Vpx-mediated SAMHD1 degradation without affecting Vpx-SAMHD1 interaction. Therefore, our findings revealed that factors in addition to Vpx-SAMHD1 binding influence the efficiency of Vpx-mediated SAMHD1 degradation. - Highlights: • SAMHD1{sub GG} from chicken could not be depleted by SIVmac Vpx. • The C-terminus of human SAMHD1{sub HS} is critical for its degradation by Vpx. • The HD domain is essential for Vpx-induced degradation of SAMHD1{sub HS}. • Altering the HD domain does not affect Vpx-SAMHD1 interaction.

  12. Endothelial glycocalyx degradation induces endogenous heparinization in patients with severe injury and early traumatic coagulopathy

    DEFF Research Database (Denmark)

    Ostrowski, Sisse R; Johansson, Pär I

    2012-01-01

    There is emerging evidence that early trauma-induced coagulopathy (TIC) is mechanistically linked to disruption of the vascular endothelium and its glycocalyx, assessed by thrombomodulin and syndecan 1, respectively. This study evaluated if degradation of the endothelial glycocalyx and ensuing...... release of its heparin-like substances induce autoheparinization and thereby contributes to TIC....

  13. Enhanced photocatalytic degradation of norfloxacin in aqueous Bi2WO6 dispersions containing nonionic surfactant under visible light irradiation

    International Nuclear Information System (INIS)

    Tang, Lin; Wang, Jiajia; Zeng, Guangming; Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi

    2016-01-01

    Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi 2 WO 6 dispersions under visible light irradiation (400–750 nm). • Cu 2+ (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi 2 WO 6 was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi 2 WO 6 dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi 2 WO 6 surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

  14. Retino-hypothalamic regulation of light-induced murine sleep

    Directory of Open Access Journals (Sweden)

    Fanuel eMuindi

    2014-08-01

    Full Text Available The temporal organization of sleep is regulated by an interaction between the circadian clock and homeostatic processes. Light indirectly modulates sleep through its ability to phase shift and entrain the circadian clock. Light can also exert a direct, circadian-independent effect on sleep. For example, acute exposure to light promotes sleep in nocturnal animals and wake in diurnal animals. The mechanisms whereby light directly influences sleep and arousal are not well understood. In this review, we discuss the direct effect of light on sleep at the level of the retina and hypothalamus in rodents. We review murine data from recent publications showing the roles of rod-, cone- and melanopsin-based photoreception on the initiation and maintenance of light-induced sleep. We also present hypotheses about hypothalamic mechanisms that have been advanced to explain the acute control of sleep by light. Specifically, we review recent studies assessing the roles of the ventrolateral preoptic area and the suprachiasmatic nucleus. We also discuss how light might differentially promote sleep and arousal in nocturnal and diurnal animals respectively. Lastly, we suggest new avenues for research on this topic which is still in its early stages.

  15. RTV Silicone Rubber Degradation Induced by Temperature Cycling

    Directory of Open Access Journals (Sweden)

    Xishan Wen

    2017-07-01

    Full Text Available Room temperature vulcanized (RTV silicone rubber is extensively used in power system due to its hydrophobicity and hydrophobicity transfer ability. Temperature has been proven to markedly affect the performance of silicone rubbers. This research investigated the degradation of RTV silicone rubber under temperature cycling treatment. Hydrophobicity and its transfer ability, hardness, functional groups, microscopic appearance, and thermal stability were analyzed using the static contact angle method, a Shore A durometer, Fourier transform infrared spectroscopy (FTIR, scanning electron microscopy (SEM, and thermogravimetry (TG, respectively. Some significant conclusions were drawn. After the temperature was cycled between −25 °C and 70 °C, the hydrophobicity changed modestly, but its transfer ability changed remarkably, which may result from the competition between the formation of more channels for the transfer of low molecular weight (LMW silicone fluid and the reduction of LMW silicone fluid in the bulk. A hardness analysis and FTIR analysis demonstrated that further cross-linking reactions occurred during the treatment. SEM images showed the changes in roughness of the RTV silicone rubber surfaces. TG analysis also demonstrated the degradation of RTV silicone rubber by presenting evidence that the content of organic materials decreased during the temperature cycling treatment.

  16. Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

    International Nuclear Information System (INIS)

    Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

    2017-01-01

    Highlights: • Bi_2Se_3 and Ni doped Bi_2Se_3 were synthesized by solvothermal approach. • Presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement. • Complete degradation of malachite green (MG) dye was achieved by Ni doped Bi_2Se_3 with H_2O_2. • Remarkable photo-catalytic degradation by doped bismuth selenide has been explained. • Scavenger tests show degradation of MG is mainly dominated by ·OH oxidation process. - Abstract: Bismuth selenide (Bi_2Se_3) and nickel (Ni) doped Bi_2Se_3 were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi_2Se_3. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi_2Se_3 sample exhibited higher photo-catalytic activity than that of the pure Bi_2Se_3 sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi_2Se_3 in presence of hydrogen peroxide (H_2O_2) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.

  17. Light-induced phenomena in polymeric thin films

    Czech Academy of Sciences Publication Activity Database

    Nešpůrek, Stanislav; Pospíšil, Jan

    2005-01-01

    Roč. 7, č. 3 (2005), s. 1157-1168 ISSN 1454-4164 R&D Projects: GA MŠk ME 700 Institutional research plan: CEZ:AV0Z40500505 Keywords : Light-induced phenomena * photodegradation * photochromism Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.138, year: 2005

  18. Preventing Ultraviolet Light-Induced Damage: The Benefits of Antioxidants

    Science.gov (United States)

    Yip, Cheng-Wai

    2007-01-01

    Extracts of fruit peels contain antioxidants that protect the bacterium "Escherichia coli" against damage induced by ultraviolet light. Antioxidants neutralise free radicals, thus preventing oxidative damage to cells and deoxyribonucleic acid. A high survival rate of UV-exposed cells was observed when grapefruit or grape peel extract was…

  19. Light-ion-induced multifragmentation. A fast, evolutionary process

    International Nuclear Information System (INIS)

    Viola, V.E.; Bracken, D.S.; Foxford, E.R.; Ginger, D.; Kwiatkowski, K.; Morley, K.B.; Hsi, W.C.; Wang, G.; Korteling, R.G.; Legrain, R.

    1996-09-01

    GeV light-ion-induced reactions offer a unique tool for preparing hot, dilute nuclear matter. Time evolution of nuclear multifragmentation in 3 He + nat Ag and 3 He + 197 Au reactions are investigated. Fragment-fragment correlations are studied in order to gain information on multifragmentation mechanism. (K.A.)

  20. Differentiation-inducing factor-1 induces cyclin D1 degradation through the phosphorylation of Thr286 in squamous cell carcinoma

    International Nuclear Information System (INIS)

    Mori, Jun; Takahashi-Yanaga, Fumi; Miwa, Yoshikazu; Watanabe, Yutaka; Hirata, Masato; Morimoto, Sachio; Shirasuna, Kanemitsu; Sasaguri, Toshiyuki

    2005-01-01

    Differentiation-inducing factors (DIFs) are morphogens which induce cell differentiation in Dictyostelium. We reported that DIF-1 and DIF-3 inhibit proliferation and induce differentiation in mammalian cells. In this study, we investigated the effect of DIF-1 on oral squamous cell carcinoma cell lines NA and SAS, well differentiated and poorly differentiated cell lines, respectively. Although DIF-1 did not induce the expression of cell differentiation makers in these cell lines, it inhibited the proliferation of NA and SAS in a dose-dependent manner by restricting the cell cycle in the G 0 /G 1 phase. DIF-1 induced cyclin D1 degradation, but this effect was prevented by treatment with lithium chloride and SB216763, the inhibitors of glycogen synthase kinase-3β (GSK-3β). Depletion of endogenous GSK-3β by RNA interference also attenuated the effect of DIF-1 on cyclin D1 degradation. Therefore, we investigated the effect of DIF-1 on GSK-3β and found that DIF-1 dephosphorylated GSK-3β on Ser 9 and induced the nuclear translocation of GSK-3β, suggesting that DIF-1 activated GSK-3β. Then, we examined the effect of DIF-1 on cyclin D1 mutants (Thr286Ala, Thr288Ala, and Thr286/288Ala). We revealed that Thr286Ala and Thr286/288Ala mutants were highly resistant to DIF-1-induced degradation compared with wild-type cyclin D1, indicating that the phosphorylation of Thr 286 was critical for cyclin D1 degradation induced by DIF-1. These results suggest that DIF-1 induces degradation of cyclin D1 through the GSK-3β-mediated phosphorylation of Thr 286

  1. Enhanced visible light photocatalytic degradation of Rhodamine B over phosphorus doped graphitic carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Bo, E-mail: willycb@163.com; Yan, Juntao; Wang, Chunlei; Ren, Zhandong; Zhu, Yuchan

    2017-01-01

    Highlights: • The phosphorus doped g-C{sub 3}N{sub 4} photocatalysts are synthesized by a co-pyrolysis procedure. • The crystal phase, morphology, and optical property of P doped g-C{sub 3}N{sub 4} are characterized. • The P doped g-C{sub 3}N{sub 4} photocatalysts show the improved photocatalytic activity. • The possible mechanism for enhanced photocatalytic activity is proposed. - Abstract: Phosphorus doped graphitic carbon nitride (g-C{sub 3}N{sub 4}) was easily synthesized using ammonium hexafluorophosphate (NH{sub 4}PF{sub 6}) as phosphorus source, and ammonium thiocyanate (NH{sub 4}SCN) as g-C{sub 3}N{sub 4} precursor, through a direct thermal co-polycondensation procedure. The obtained phosphorus doped g-C{sub 3}N{sub 4} was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), UV–vis diffuse reflectance absorption spectra (UV-DRS), photoelectrochemical measurement and photoluminescence spectra (PL). The photocatalytic activities of phosphorus doped g-C{sub 3}N{sub 4} samples were evaluated by degradation of Rhodamine B (RhB) solution under visible light irradiation. The results showed that the phosphorus doped g-C{sub 3}N{sub 4} had a superior photocatalytic activity than that of pristine g-C{sub 3}N{sub 4}, attributing to the phosphorus atoms substituting carbon atoms of g-C{sub 3}N{sub 4} frameworks to result in light harvesting enhancement and delocalized π-conjugated system of this copolymer, beneficial for the increase of photocatalytic performance. The photoelectrochemical measurements also verified that the charge carrier separation efficiency was promoted by phosphorus doping g-C{sub 3}N{sub 4}. Moreover, the tests of radical scavengers demonstrated that the holes (h{sup +}) and superoxide radicals (·O{sub 2}{sup −}) were the main active species for the

  2. Process-induced degradation of bioresorbable PDLGA in bone tissue scaffold production.

    Science.gov (United States)

    Little, H; Clarke, S A; Cunningham, E; Buchanan, F

    2017-12-28

    Process-induced degradation of clinically relevant resorbable polymers was investigated for two thermal techniques, filament extrusion followed by fused deposition modelling (FDM). The aim was to develop a clear understanding of the relationship between temperature, processing time and resultant process-induced degradation. This acts to address the current knowledge gap in studies involving thermal processing of resorbable polymers. Poly(DL-lactide-co-glycolide) (PDLGA) was chosen for its clinically relevant resorption properties. Furthermore, a comparative study of controlled thermal exposure was conducted through compression moulding PDLGA at a selected range of temperatures (150-225 °C) and times (0.5-20 min). Differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) were used to characterise thermally induced degradation behaviour. DSC proved insensitive to degradation effects, whereas GPC demonstrated distinct reductions in molecular weight allowing for the quantification of degradation. A near-exponential pattern of degradation was identified. Through the application of statistical chain scission equations, a predictive plot of theoretical degradation was created. Thermal degradation was found to have a significant effect on the molecular weight with a reduction of up to 96% experienced in the controlled processing study. The proposed empirical model may assist prediction of changes in molecular weight, however, accuracy limitations are highlighted for twin-screw extrusion, accredited to high-shear mixing. The results from this study highlight the process sensitivity of PDLGA and proposes a methodology for quantification and prediction, which contributes to efforts in understanding the influence of manufacture on performance of degradable medical implants.

  3. Degradation of protein translation machinery by amino acid starvation-induced macroautophagy

    DEFF Research Database (Denmark)

    Gretzmeier, Christine; Eiselein, Sven; Johnson, Gregory R.

    2017-01-01

    , unbiased approaches relying on quantitative mass spectrometry-based proteomics. Macroautophagy is induced by rapamycin treatment, and by amino acid and glucose starvation in differentially, metabolically labeled cells. Protein dynamics are linked to image-based models of autophagosome turnover. Depending...... on the inducing stimulus, protein as well as organelle turnover differ. Amino acid starvation-induced macroautophagy leads to selective degradation of proteins important for protein translation. Thus, protein dynamics reflect cellular conditions in the respective treatment indicating stimulus-specific pathways...

  4. Heavy Ion Induced Degradation in SiC Schottky Diodes: Bias and Energy Deposition Dependence

    Science.gov (United States)

    Javanainen, Arto; Galloway, Kenneth F.; Nicklaw, Christopher; Bosser, Alexandre L.; Ferlet-Cavrois, Veronique; Lauenstein, Jean-Marie; Pintacuda, Francesco; Reed, Robert A.; Schrimpf, Ronald D.; Weller, Robert A.; hide

    2016-01-01

    Experimental results on ion-induced leakage current increase in 4H-SiC Schottky power diodes are presented. Monte Carlo and TCAD simulations show that degradation is due to the synergy between applied bias and ion energy deposition. This degradation is possibly related to thermal spot annealing at the metal semiconductor interface. This thermal annealing leads to an inhomogeneity of the Schottky barrier that could be responsible for the increase leakage current as a function of fluence.

  5. Highly efficient degradation of thidiazuron with Ag/AgCl- activated carbon composites under LED light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yisi [College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128 (China); Hubei Key Laboratory for Processing and Application of Catalytic Materials, Huanggang Normal University, Huanggang 438000 (China); College of Chemical Engineering, Huanggang Normal University, Huanggang 438000 (China); Zhang, Yan [Hubei Key Laboratory for Processing and Application of Catalytic Materials, Huanggang Normal University, Huanggang 438000 (China); College of Chemical Engineering, Huanggang Normal University, Huanggang 438000 (China); Dong, Mingguang; Yan, Ting; Zhang, Maosheng [College of Chemical Engineering, Huanggang Normal University, Huanggang 438000 (China); Zeng, Qingru, E-mail: 40083763@qq.com [College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128 (China)

    2017-08-05

    Highlights: • Photocatalytic degradation of thidiazuron was performed in a neutral water matrix. • This was carried out in the presence of Ag/AgCl-activated carbon composites and LED light. • The pH effect and the dominant active species were explored. • Degradation products and pathways in water were studied for the first time. - Abstract: Thidiazuron (TDZ; 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea) is one of the most widely used defoliant and easy to dissolve in surface water. Risk associated with the pesticide is not clearly defined, so it is important to remove/degrade TDZ with an efficient and environment friendly technology. Here, we investigated the use of Ag/AgCl-activated carbon (Ag/AgCl–AC) composites in photocatalytic degradation of TDZ under LED light. By the synergic effect of Ag/AgCl and AC, the optimum Ag/carbon weight ratio of 2:1 exhibited superior visible-light photocatalytic activity, the highest removal efficiency was close to 91% in pH 7 matrix. Different types of Ag/AgCl–AC composites were tested, all showed much faster photodegradation kinetics than bare Ag/AgCl in 210 min. The degradation products as identified by HPLC–MS revealed that the hydroxylation by hydroxyl radicals and that of oxidation by superoxide radicals as well as holes were the two main pathways for TDZ degradation. Results revealed that the adsorption concentrated TDZ molecules and the photocatalytically generated radicals rapidly degradated TDZ, the two contributions functioned together for removal of the pollutant from water.

  6. Highly efficient degradation of thidiazuron with Ag/AgCl- activated carbon composites under LED light irradiation

    International Nuclear Information System (INIS)

    Yang, Yisi; Zhang, Yan; Dong, Mingguang; Yan, Ting; Zhang, Maosheng; Zeng, Qingru

    2017-01-01

    Highlights: • Photocatalytic degradation of thidiazuron was performed in a neutral water matrix. • This was carried out in the presence of Ag/AgCl-activated carbon composites and LED light. • The pH effect and the dominant active species were explored. • Degradation products and pathways in water were studied for the first time. - Abstract: Thidiazuron (TDZ; 1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea) is one of the most widely used defoliant and easy to dissolve in surface water. Risk associated with the pesticide is not clearly defined, so it is important to remove/degrade TDZ with an efficient and environment friendly technology. Here, we investigated the use of Ag/AgCl-activated carbon (Ag/AgCl–AC) composites in photocatalytic degradation of TDZ under LED light. By the synergic effect of Ag/AgCl and AC, the optimum Ag/carbon weight ratio of 2:1 exhibited superior visible-light photocatalytic activity, the highest removal efficiency was close to 91% in pH 7 matrix. Different types of Ag/AgCl–AC composites were tested, all showed much faster photodegradation kinetics than bare Ag/AgCl in 210 min. The degradation products as identified by HPLC–MS revealed that the hydroxylation by hydroxyl radicals and that of oxidation by superoxide radicals as well as holes were the two main pathways for TDZ degradation. Results revealed that the adsorption concentrated TDZ molecules and the photocatalytically generated radicals rapidly degradated TDZ, the two contributions functioned together for removal of the pollutant from water.

  7. Radiation-induced oxidative degradation of poly(vinyl chloride)

    International Nuclear Information System (INIS)

    Hegazy, E.S.A.; Seguchi, T.; Machi, S.

    1981-01-01

    Gas evolution and oxygen consumption in the γ-irradiation of PVC were studied. The gas evolution and the oxidative degradation are retarded by the presence of plasticizers and stabilizers. The G(HCl) and G(H 2 ) are 8 and 0.24 for the irradiation of pure PVC under vacuum and 0.02 and 0.14 for that of plasticized PVC, respectively. Gas evolution increases in the presence of oxygen, specially for the pure PVC. The G(-O 2 ) values for the pure and plasticized PVC are 30 and 12, respectively. The dependence of gas evolution and oxygen consumption on the oxygen pressure is more pronounced for the plasticized PVC than pure PVC because the oxygen diffusion is controlled

  8. A study on heterogeneous photocatalytic degradation of various organic compounds using N-Tio2 under Uv-light irradiation

    Science.gov (United States)

    Srujana, Dhegam; Sailu, Chinta

    2018-04-01

    The aim of this work is to determine the photocatalytic degradation of mixture of four selected organic compounds are Congo Red (CR), Methylene Blue (MB), Diclofenaec (DC), 4-Chlorophenol (4-CP) have been subjected to Photo catalytic degradation by Ultraviolet (λ=254nm) radiation in presence of Nitrogen-doped Titanium dioxide (N-TiO2) catalyst. This paper focused on the enhancement of photo catalysis by modification of TiO2 employing non-metal ion (Nitrogen) doping. Experiments are conducted with a mixture of equal proportions of organic compounds (CR, MB, DC, and 4-CP) with combined concentrations of 10, 20, 30, 40 and 50 mg/l in water in a batch reactor in presence of N-TiO2catalyst with UV light (λ=254nm). The rate of degradation of each compound is determined by using spectrophotometer. The kinetics of degradation of the selected organic compounds is followed first order rate.

  9. A novel visible light-driven Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite: Preparation and application in the photo-degradation of pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Yuanyuan; Wang, Li; Ren, Jia; Dai, Wei-Lin, E-mail: wldai@fudan.edu.cn

    2015-01-01

    Graphical abstract: - Highlights: • Highly efficient visible-light-driven Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite. • Application in the photo-degradation of RhB. • Synthesis from a facile and simple colloidal method. • 20%-Ag{sub 3}PO{sub 4}/SBA-15 shows 8 times faster degradation rate than Ag{sub 3}PO{sub 4}. • Super stability and recycling ability. - Abstract: A novel visible light-driven environmental-benign Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite photo-catalyst was synthesized for the photo-degradation of pollutants. The exploration on adsorption and photo-catalysis of dye or organic pollution for the nanocomposite was carried out. The adsorption capability for Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite increases by 3 times compared with that of the Ag{sub 3}PO{sub 4} particles. The photo-catalytic activity of nanocomposite is higher than pristine Ag{sub 3}PO{sub 4} nanoparticle for the degradation of RhB or MO under visible light irradiation (λ > 420 nm). The effect of Ag{sub 3}PO{sub 4} loading on the catalytic performance was also studied. The results show that the optimum degradation is achieved over 20% Ag{sub 3}PO{sub 4}/SBA-15. Compared to pure Ag{sub 3}PO{sub 4} nanoparticle, the most efficient catalyst showed 8 times higher photo-catalytic activity for the degradation of RhB. The Ag{sub 3}PO{sub 4}/SBA-15 catalysts were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS), and N{sub 2}-adsorption–desorption isotherms (BET). A possible mechanism scheme regarding photo-degradation enhancement induced by dye enrichments has been proposed on the Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite. Additionally, the SBA-15 support can enhance the efficiency of separation of catalyst from the reaction mixture, implying that the Ag{sub 3}PO{sub 4} loading on the SBA-15 catalyst will not result in the extra environment and health

  10. A novel visible light-driven Ag3PO4/SBA-15 nanocomposite: Preparation and application in the photo-degradation of pollutants

    International Nuclear Information System (INIS)

    Chai, Yuanyuan; Wang, Li; Ren, Jia; Dai, Wei-Lin

    2015-01-01

    Graphical abstract: - Highlights: • Highly efficient visible-light-driven Ag 3 PO 4 /SBA-15 nanocomposite. • Application in the photo-degradation of RhB. • Synthesis from a facile and simple colloidal method. • 20%-Ag 3 PO 4 /SBA-15 shows 8 times faster degradation rate than Ag 3 PO 4 . • Super stability and recycling ability. - Abstract: A novel visible light-driven environmental-benign Ag 3 PO 4 /SBA-15 nanocomposite photo-catalyst was synthesized for the photo-degradation of pollutants. The exploration on adsorption and photo-catalysis of dye or organic pollution for the nanocomposite was carried out. The adsorption capability for Ag 3 PO 4 /SBA-15 nanocomposite increases by 3 times compared with that of the Ag 3 PO 4 particles. The photo-catalytic activity of nanocomposite is higher than pristine Ag 3 PO 4 nanoparticle for the degradation of RhB or MO under visible light irradiation (λ > 420 nm). The effect of Ag 3 PO 4 loading on the catalytic performance was also studied. The results show that the optimum degradation is achieved over 20% Ag 3 PO 4 /SBA-15. Compared to pure Ag 3 PO 4 nanoparticle, the most efficient catalyst showed 8 times higher photo-catalytic activity for the degradation of RhB. The Ag 3 PO 4 /SBA-15 catalysts were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS), and N 2 -adsorption–desorption isotherms (BET). A possible mechanism scheme regarding photo-degradation enhancement induced by dye enrichments has been proposed on the Ag 3 PO 4 /SBA-15 nanocomposite. Additionally, the SBA-15 support can enhance the efficiency of separation of catalyst from the reaction mixture, implying that the Ag 3 PO 4 loading on the SBA-15 catalyst will not result in the extra environment and health problems and reduce the cost of wastewater treatment

  11. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    Directory of Open Access Journals (Sweden)

    Zatil Amali Che Ramli

    2014-01-01

    Full Text Available This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC, TiO2/carbon (C, and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared (FTIR, thermogravimetric analysis (TG-DTA, Brunauer-Emmet-Teller (BET, and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m2 g−1. The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples.

  12. Distinct functional domains contribute to degradation of the low density lipoprotein receptor (LDLR) by the E3 ubiquitin ligase inducible Degrader of the LDLR (IDOL)

    NARCIS (Netherlands)

    Sorrentino, Vincenzo; Scheer, Lilith; Santos, Ana; Reits, Eric; Bleijlevens, Boris; Zelcer, Noam

    2011-01-01

    We recently identified the liver X receptor-regulated E3 ubiquitin ligase inducible degrader of the LDL receptor (IDOL) as a modulator of lipoprotein metabolism. Acting as an E3 ubiquitin ligase, IDOL triggers ubiquitination and subsequent degradation of the low density lipoprotein receptor (LDLR).

  13. Synthesis of metal free ultrathin graphitic carbon nitride sheet for photocatalytic dye degradation of Rhodamine B under visible light irradiation

    Science.gov (United States)

    Rahman, Shakeelur; Momin, Bilal; Higgins M., W.; Annapure, Uday S.; Jha, Neetu

    2018-04-01

    In recent times, low cost and metal free photocatalyts driven under visible light have attracted a lot of interest. One such photo catalyst researched extensively is bulk graphitic carbon nitride sheets. But the low surface area and weak mobility of photo generated electrons limits its photocatalytic performance in the visible light spectrum. Here we present the facile synthesis of ultrathin graphitic carbon nitride using a cost effective melamine precursor and its application in highly efficient photocatalytic dye degradation of Rhodamine B molecules. Compared to bulk graphitic carbon nitride, the synthesized ultrathin graphitic carbon nitride shows an increase in surface area, a a decrease in optical band gap and effective photogenerated charge separation which facilitates the harvest of visible light irradiation. Due to these optimal properties of ultrathin graphitic carbon nitride, it shows excellent photocatalytic activity with photocatalytic degradation of about 95% rhodamine B molecules in 1 hour.

  14. Photolysis of polycyclic aromatic hydrocarbons (PAHs) on Fe3+-montmorillonite surface under visible light: Degradation kinetics, mechanism, and toxicity assessments.

    Science.gov (United States)

    Zhao, Song; Jia, Hanzhong; Nulaji, Gulimire; Gao, Hongwei; Wang, Fu; Wang, Chuanyi

    2017-10-01

    Photochemical behavior of various polycyclic aromatic hydrocarbons (PAHs) on Fe 3+ -modified montmorillonite was explored to determine their potential kinetics, pathways, and mechanism under visible light. Depending on the type of PAH molecules, the transformation rate follows the order of benzo[a]pyrene ≈ anthracene > benzo[a]anthracene > phenanthrene. Quantum simulation results confirm the crucial role of "cation-π" interaction between Fe 3+ and PAHs on their transformation kinetics. Primary intermediates, including quinones, ring-opening products and benzene derivatives, were identified by gas chromatography-mass spectrometer (GC-MS), and the possible photodegradation pathway of benzo[a]pyrene was proposed. Meanwhile, radical intermediates, such as reactive oxygen species (ROS) and free organic radicals, were detected by electron paramagnetic resonance (EPR) technique. The photolysis of selected PAHs, such as anthracene and benzo[a]pyrene, on clay surface firstly occurs by electron transfer from PAHs to Fe 3+ -montmorillonite, followed by degradation involving photo-induced ROS such as ·OH and ·O 2 - . To investigate the acute toxicity of photolysis products, the Microtox ® toxicity test was performed during the photodegradation processes of various PAHs. As a result, the photo-irradiation initially induces increased toxicity by generating reactive intermediates, such as free organic radicals, and then the toxicity gradually decreases with increasing of reaction time. Overall, the present study provides useful information to understand the fate and photo-transformation of PAHs in contaminated soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Study on radiation degradation of hydroxylamine derivatives. Pt.2: The qualitative and quantitative analysis of light hydrocarbons produced by radiation degradation of N, N-diethyl hydroxylamine

    International Nuclear Information System (INIS)

    Wang Jinhua; Bao Borong; Wu Minghong; Sun Xilian

    2004-01-01

    The qualitative and quantitative analysis of light hydrocarbons produced by radiation degradation of N,N-diethyl hydroxylamine are reported. These analyses are performed on the gas chromatography in which a porous layer open tubular column coated with aluminum oxide and a flame-ionization detector are used. When the doses are between 10 and 1000 kGy, the main hydrocarbons produced by radiation degradation of N,N-diethyl hydroxylamine are methane, ethane, ethene, propane and n-butane. The volume fraction of methane, ethane, n-butane and propane are increased with the increase of dose. The volume fraction of ethene is also increased with the increase of dose at first, however, when the absorbed dose is higher than 500 kGy. The volume fraction of ethene is decreased with the increase of dose

  16. Disordered resonant media: Self-induced transparency versus light localization

    Science.gov (United States)

    Novitsky, Denis V.

    2018-01-01

    We propose a concept of disordered resonant media, which are characterized by random variations of their parameters along the light propagation direction. In particular, a simple model of disorder considered in the paper implies random change of the density of active particles (two-level atoms). Within this model, the effect of disorder on self-induced transparency (SIT) is analyzed using numerical simulations of light pulse propagation through the medium. The transition from the SIT to localization regime is revealed as well as its dependence on the disorder level, atom density, medium thickness, and period of random variations.

  17. Light induced modulation instability of surfaces under intense illumination

    KAUST Repository

    Burlakov, V. M.

    2013-12-17

    We show that a flat surface of a polymer in rubber state illuminated with intense electromagnetic radiation is unstable with respect to periodic modulation. Initial periodic perturbation is amplified due to periodic thermal expansion of the material heated by radiation. Periodic heating is due to focusing-defocusing effects caused by the initial surface modulation. The surface modulation has a period longer than the excitation wavelength and does not require coherent light source. Therefore, it is not related to the well-known laser induced periodic structures on polymer surfaces but may contribute to their formation and to other phenomena of light-matter interaction.

  18. Facile synthesis of aluminium doped zinc oxide-polyaniline hybrids for photoluminescence and enhanced visible-light assisted photo-degradation of organic contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Mousumi [Department of Physics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, West Bengal (India); Ghosh, Amrita; Mondal, Anup [Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, West Bengal (India); Kargupta, Kajari [Department of Chemical Engineering, Jadavpur University, Kolkata 700032, West Bengal (India); Ganguly, Saibal [Department of Chemical Engineering, BITS Pilani, K K Birla Goa Campus, NH 17 B Bypass Road, Zuarinagar, Sancoale, Goa 403726 (India); Banerjee, Dipali, E-mail: dipalibanerjeebesu@gmail.com [Department of Physics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, West Bengal (India)

    2017-04-30

    species and accordingly a mechanism was proposed. Electrochemical impedance spectroscopy and linear scan voltammetry under dark and visible-light irradiation also established the visible-light activity of the PAZ hybrid due to decrease in the electron transfer resistance that resulted in an enhancement in photocurrent. The significant enhancement of photo degradation may be attributed to the efficiency of charge separation, induced by synergistic effect between an organic conductor PANI and an inorganic semiconductor AlZnO. Owing to its superior photo electrochemical performance and photocatalytic degradation, aluminium doped zinc oxide-polyaniline (PAZ) hybrid offers stable and efficient organic-inorganic hybrid hetero-structures in near future.

  19. Light-Induced Alterations in Basil Ganglia Kynurenic Acid Levels

    Science.gov (United States)

    Sroufe, Angela E.; Whittaker, J. A.; Patrickson, J. W.; Orr, M. C.

    1997-01-01

    The metabolic synthesis, release and breakdown of several known CNS neurotransmitters have been shown to follow a circadian pattern entrained to the environmental light/dark cycle. The levels of excitatory amino acid (EAA) transmitters such as glutamate, have been shown to vary with environmental lighting conditions. Kynurenic Acid (KA), an endogenous tryptophan metabolite and glutamate receptor antagonist, has been reported to have neuroprotective effects against EAA-induced excitotoxic cell damage. Changes in KA's activity within the mammalian basal ganglia has been proposed as being contributory to neurotoxicity in Huntington's Disease. It is not known whether CNS KA levels follow a circadian pattern or exhibit light-induced fluctuations. However, because the symptoms of certain degenerative motor disorders seem to fluctuate with daily 24 hour rhythm, we initiated studies to determine if basal ganglia KA were influenced by the daily light/dark cycle and could influence motor function. Therefore in this study, HPLC-EC was utilized to determine if basal ganglia KA levels in tissue extracts from adult male Long-Evans rats (200-250g) entrained to 24 and 48 hours constant light and dark conditions, respectively. Samples were taken one hour before the onset of the subjective day and one hour prior to the onset of the subjective night in order to detect possible phase differences in KA levels and to allow for accumulation of factors expressed in association with the light or dark phase. Data analysis revealed that KA levels in the basal ganglia vary with environmental lighting conditions; being elevated generally during the dark. Circadian phase differences in KA levels were also evident during the subjective night and subjective day, respectively. Results from these studies are discussed with respect to potential cyclic changes in neuronal susceptibility to excitotoxic damage during the daily 24 hour cycle and its possible relevance to future therapeutic approaches in

  20. Enhanced photosensitized degradation of rhodamine B on CdS/TiO{sub 2} nanocomposites under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenjuan [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Sciences and Engineering, Nanjing 210044 (China); Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Shandong Province Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165 (China); Cui, Xiaoli [Shandong Province Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu 273165 (China); Wang, Peixian; Shao, Yu [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Li, Danzhen, E-mail: dzli@fzu.edu.cn [Research Institute of Photocatalysis, State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Teng, Fei [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Sciences and Engineering, Nanjing University of Information Sciences and Engineering, Nanjing 210044 (China)

    2013-09-01

    Graphical abstract: The photosensitized degradation of RhB was largely enhanced by the synergistic effect of the RhB and CdS/TiO{sub 2} nanocomposite. The composite of the two inorganic semiconductors with appropriate oxidation reduction energy levels enhanced the charge separation and extended the absorption response to visible region. - Highlights: • CdS/TiO{sub 2} nanocomposites were synthesized by a simple hydrothermal method. • Samples prepared at 200 °C, 12 h, CdS/TiO{sub 2} = 12% possessed the best activity. • The photosensitized degradation of RhB was largely enhanced by the composite. • The better activity was due to the synergistic effect of the RhB and CdS/TiO{sub 2}. - Abstract: Visible-light-driven photocatalysts, CdS/TiO{sub 2} nanocomposites were synthesized by a simple hydrothermal method. Their formation and structures were characterized by X-ray diffractometer, transmission electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Taking rhodamine B (RhB) as a model, their photocatalytic activities in aqueous phase under visible light irradiation (420 < λ < 800 nm) were tested. The results showed that the composite of CdS and TiO{sub 2} with appropriate oxidation reduction energy levels enhanced the charge separation and extended the absorption response into visible light region. Thus, the photosensitized degradation of RhB was largely enhanced. The degradation mechanism was explored concretely.

  1. Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination

    International Nuclear Information System (INIS)

    Saravanan, R.; Karthikeyan, S.; Gupta, V.K.; Sekaran, G.; Narayanan, V.; Stephen, A.

    2013-01-01

    The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV–visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail. Highlights: ► Visible light active photocatalyst ► Degradation of methylene blue and methyl orange ► Preparation of composite materials is a simple, fast and cost effective method. ► Nano composite materials ► Degradation of textile waste water

  2. Evaluation of Maltose-Induced Chemical Degradation at the Interface of Bilayer Tablets.

    Science.gov (United States)

    Matsuzaki, Naoya; Yamamoto, Yousuke; Murayama, Daisuke; Katakawa, Yoshifumi; Mimura, Hisashi; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

    2017-01-01

    Fixed dose combination tablets consisting of mirabegron (MB) and solifenacin succinate (SS) were developed and formulated into bilayer tablets in the current study. The results of a chemical stability study showed that the original formulation for the tablets led to a significant increase of unknown degradants in the SS layer. Two compatibility studies were conducted to simulate the interface between the MB and SS layers, and the results revealed that the degradants only formed in the presence of both active pharmaceutical ingredients (APIs), and that the presence of maltose in the SS layer was critical to inducing degradation. High resolution mass spectroscopy coupled with high performance liquid chromatography was used to determine the chemical structures of the degradants, which were identified to MB derivatives bearing one or two sugar units. These findings therefore suggested that the degradation of the API could be attributed to the addition of sugar units from maltose to MB under the acidic conditions caused by SS. With this in mind, we developed a new formulation by replacing maltose with hydroxypropyl cellulose as a polymer-type binder. The results showed that this formulation suppressed the formation of the degradants. The results of this study have shown that chemical degradation can occur at the interface of bilayer tablets and that an alternative strategy is available to formulate more stable MB/SS bilayer tablets.

  3. Light-induced aggregation of microbial exopolymeric substances.

    Science.gov (United States)

    Sun, Luni; Xu, Chen; Zhang, Saijin; Lin, Peng; Schwehr, Kathleen A; Quigg, Antonietta; Chiu, Meng-Hsuen; Chin, Wei-Chun; Santschi, Peter H

    2017-08-01

    Sunlight can inhibit or disrupt the aggregation process of marine colloids via cleavage of high molecular weight compounds into smaller, less stable fragments. In contrast, some biomolecules, such as proteins excreted from bacteria can form aggregates via cross-linking due to photo-oxidation. To examine whether light-induced aggregation can occur in the marine environment, we conducted irradiation experiments on a well-characterized protein-containing exopolymeric substance (EPS) from the marine bacterium Sagitulla stellata. Our results show that after 1 h sunlight irradiation, the turbidity level of soluble EPS was 60% higher than in the dark control. Flow cytometry also confirmed that more particles of larger sized were formed by sunlight. In addition, we determined a higher mass of aggregates collected on filter in the irradiated samples. This suggests light can induce aggregation of this bacterial EPS. Reactive oxygen species hydroxyl radical and peroxide played critical roles in the photo-oxidation process, and salts assisted the aggregation process. The observation that Sagitulla stellata EPS with relatively high protein content promoted aggregation, was in contrast to the case where no significant differences were found in the aggregation of a non-protein containing phytoplankton EPS between the dark and light conditions. This, together with the evidence that protein-to-carbohydrate ratio of aggregates formed under light condition is significantly higher than that formed under dark condition suggest that proteins are likely the important component for aggregate formation. Light-induced aggregation provides new insights into polymer assembly, marine snow formation, and the fate/transport of organic carbon and nitrogen in the ocean. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Electric currents induced by twisted light in Quantum Rings.

    Science.gov (United States)

    Quinteiro, G F; Berakdar, J

    2009-10-26

    We theoretically investigate the generation of electric currents in quantum rings resulting from the optical excitation with twisted light. Our model describes the kinetics of electrons in a two-band model of a semiconductor-based mesoscopic quantum ring coupled to light having orbital angular momentum (twisted light). We find the analytical solution, which exhibits a "circular" photon-drag effect and an induced magnetization, suggesting that this system is the circular analog of that of a bulk semiconductor excited by plane waves. For realistic values of the electric field and material parameters, the computed electric current can be as large as microA; from an applied perspective, this opens new possibilities to the optical control of the magnetization in semiconductors.

  5. Light-induced atomic desorption and related phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Burchianti, A; Bogi, A; Marinelli, C; Mariotti, E; Moi, L [CNISM and Physics Department, University of Siena, 53100 Siena (Italy)], E-mail: burchianti@unisi.it

    2009-07-15

    We review some recent studies on light-induced atomic desorption (LIAD) from dielectric surfaces. Alkali-metal atoms adsorbed either on organic films or on porous glass are released into the vapor phase under illumination. The measurements were performed in Pyrex resonance cells either coated with siloxane films or containing a porous glass sample. In both cases, the experimental results show that LIAD can be used to produce atomic densities suitable for most atomic physics experiments. Moreover, we find that photoinduced effects, correlated with LIAD, produce reversible formation and evaporation of alkali-metal clusters in porous glass. These processes depend on the light frequency, making the porous glass transmittance controllable by light.

  6. Quantum correlations induced by multiple scattering of quadrature squeezed light

    DEFF Research Database (Denmark)

    Lodahl, Peter

    2006-01-01

    Propagating quadrature squeezed light through a multiple scattering random medium is found to induce pronounced spatial quantum correlations that have no classical analogue. The correlations are revealed in the number of photons transported through the sample that can be measured from the intensity...... fluctuations of the total transmission or reflection. In contrast, no pronounced spatial quantum correlations appear in the quadrature amplitudes where excess noise above the shot noise level is found....

  7. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    CERN Document Server

    Vaidya, S J; Shaikh, A M; Chandorkar, A N

    2002-01-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co sup 6 sup 0 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radi...

  8. Radiation degradation of polysaccharides and induced biological activity

    Energy Technology Data Exchange (ETDEWEB)

    Nagasawa, Naotsugu; Yoshii, Fumio; Makuuchi Keizo; Kume Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Mitomo, Hiroshi [Gunma Univ., Kiryu (Japan). Faculty of Engineering

    1999-09-01

    Relationship between irradiation effect of polysaccharides and induced biological activity for plants has been investigated. Sodium alginate was irradiated by gamma-rays from a Co-60 source in liquid state (aqueous solution) and in solid state (powder form). Measurement of molecular weight and analysis of UV spectra of irradiated sodium alginate have been carried out. The molecular weight was decreased by irradiation in both conditions. New absorbance peak derived from double bond or/and carbonyl group was appeared at close to 267 nm by irradiation in UV spectra. It was found that alginate having molecular weight about 10,000 is most suitable to used as growth promoter in plants. To obtain the molecular weight of 10,000 by irradiation, the necessary doses are 100 kGy in liquid state and 500 kGy in solid state, respectively. (author)

  9. Interleukin-1 Acts via the JNK-2 Signaling Pathway to Induce Aggrecan Degradation by Human Chondrocytes.

    Science.gov (United States)

    Ismail, Heba M; Yamamoto, Kazuhiro; Vincent, Tonia L; Nagase, Hideaki; Troeberg, Linda; Saklatvala, Jeremy

    2015-07-01

    Aggrecan enables articular cartilage to bear load and resist compression. Aggrecan loss occurs early in osteoarthritis and rheumatoid arthritis and can be induced by inflammatory cytokines such as interleukin-1 (IL-1). IL-1 induces cleavage of specific aggrecans characteristic of the ADAMTS proteinases. The aim of this study was to identify the intracellular signaling pathways by which IL-1 causes aggrecan degradation by human chondrocytes and to investigate how aggrecanase activity is controlled by chondrocytes. We developed a cell-based assay combining small interfering RNA (siRNA)-induced knockdown with aggrecan degradation assays. Human articular chondrocytes were overlaid with bovine aggrecan after transfection with siRNAs against molecules of the IL-1 signaling pathway. After IL-1 stimulation, released aggrecan fragments were detected with AGEG and ARGS neoepitope antibodies. Aggrecanase activity and tissue inhibitor of metalloproteinases 3 levels were measured by enzyme-linked immunosorbent assay. Low-density lipoprotein receptor-related protein 1 (LRP-1) shedding was analyzed by Western blotting. ADAMTS-5 is a major aggrecanase in human chondrocytes, regulating aggrecan degradation in response to IL-1. The tumor necrosis factor receptor-associated 6 (TRAF-6)/transforming growth factor β-activated kinase 1 (TAK-1)/MKK-4 signaling axis is essential for IL-1-induced aggrecan degradation, while NF-κB is not. Of the 3 MAPKs (ERK, p38, and JNK), only JNK-2 showed a significant role in aggrecan degradation. Chondrocytes constitutively secreted aggrecanase, which was continuously endocytosed by LRP-1, keeping the extracellular level of aggrecanase low. IL-1 induced aggrecanase activity in the medium in a JNK-2-dependent manner, possibly by reducing aggrecanase endocytosis, because IL-1 caused JNK-2-dependent shedding of LRP-1. The signaling axis TRAF-6/TAK-1/MKK-4/JNK-2 mediates IL-1-induced aggrecanolysis. The level of aggrecanase is controlled by its

  10. Mechanism of radiation-induced degradation of poly(methyl methacrylate)

    International Nuclear Information System (INIS)

    Ichikawa, Tsuneki; Oyama, Ken-ichi; Yoshida, Hiroshi

    1995-01-01

    ESR and gel permeation chromatographic measurements of poly(methyl methacrylate) γ-irradiated between 77 K and 300 K have been carried out to elucidate the mechanism of radiation-induced degradation of the polymer. It is revealed that the scission of the main chain is not taken place immediately after the absorption of radiation energy but is induced by the intramolecular radical conversion of the side-chain -COOCH 2 radical to the tertiary -CH 2 -C(CH 3 )- radical followed by the main-chain β-scission of the latter radical. The degradation is not taken place below 190 K, because the side-chain radical starts to convert only above 190 K. The residual monomer in the polymer reacts with the side-chain radical below 190 K to generate the stable propagating-type radical, so that the degradation is suppressed even after warming the polymer to the ambient temperature. (author)

  11. A novel photocatalytic material for removing microcystin-LR under visible light irradiation: degradation characteristics and mechanisms.

    Directory of Open Access Journals (Sweden)

    Xin Sui

    Full Text Available Microcystin-LR (MC-LR, a common toxic species in contaminated aquatic systems, persists for long periods because of its cyclic structure. Ag3PO4 is an environment-friendly photocatalyst with relatively good degradation capacity for hazardous organic pollutants. This study aimed to investigate the degradation capacity of Ag3PO4 for MC-LR under visible light.An Ag3PO4 photocatalyst was synthesized by the ion-exchange method and characterized by X-ray diffraction, field-emission scanning electron microscope, and UV-Vis spectrophotometer. MC-LR was quantified in each sample through high-performance liquid chromatograph. The degradation efficiency of MC-LR was affected by initial pH, initial Ag3PO4 concentration, initial MC-LR concentration, and recycle experiments. The degradation intermediates of MC-LR were examined by liquid chromatography-mass spectrometry (LC/MS.The degradation process can be well fitted with the pseudo-first-order kinetic model. The maximum MC-LR degradation rate of 99.98% can be obtained within 5 h under the following optimum conditions: pH of 5.01, Ag3PO4 concentration of 26.67 g/L, and MC-LR concentration of 9.06 mg/L. Nine intermediates were detected and analyzed by LC/MS. Three main degradation pathways were proposed based on the molecular weight of the intermediates and the reaction mechanism: (1 hydroxylation on the aromatic ring of Adda, (2 hydroxylation on the diene bonds of Adda, and (3 internal interactions on the cyclic structure of MC-LR.Ag3PO4 is a highly efficient catalyst for MC-LR degradation in aqueous solutions.

  12. Human-induced environmental degradation during Anthropocene in Turkey

    Science.gov (United States)

    Efe, Recep; Curebal, Isa; Soykan, Abdullah; Sönmez, Suleyman

    2015-04-01

    ., 2011; Dalton et al., 2014). Domestic tourism boomed after 1970, which led the Sea of Marmara, Aegean, and Mediterranean coasts to become secondary settlement areas for city-dwellers. This, in turn, sparked the construction of concrete buildings along the coastlines, making them less natural. The shift from the agricultural society to the industrial society made it possible for the service sector to grow and develop. Land transportation among large cities gained importance, and road construction gained pace. Development of industry, rapid rise in population, migration from rural areas to cities, unplanned settlement, and wrong agricultural practices are main factors for the environmental degradation in Turkey. Key Words: Human, habitat, anthropocene, industrialization, Turkey. References Andersson, A.J.; Mackenzie, F.T.; Lerman, A. (2006), Coastal ocean CO 2 carbonic acid carbonate sediment system of the Anthropocene, Global Biogeochemical Cycles, 20: 1-13 Braje, T.J.; Erlandson, J.M. (2014), Looking forward, looking back: Humans, anthropogenic change and the Anthropocene, Anthropocene, 4: 116-121 Crossland, C.J. ed (2005), Coastal fluxes in the Anthropocene. Berlin: Springer. 231-pp. Crutzen, P. J. and Stoermer, E.F. (2000), The Anthropocene. Global Change Newsletter (41): 17-18. Crutzen, P.J. (2002), Geology of Mankind: The Anthropocene. Nature, 415: 23 Crutzen P.J.; Steffen, W. (2003), How long have we been in the Anthropocene Era? Climatic Change, Vol. 61, No. 3. Cürebal, I.; Efe, R.; Soykan, A.; Sonmez, S. (2015), Impacts of anthropogenic factors on land degradation during the anthropocene in Turkey, Journal of Environmental Biology, Volume 36, Special Issue, 51-58 Dalton, C.; ODwyer, B.; Taylor, D.; de Eyto, E.; Jennings, E.; Chen, G.; Poole, R.; Dillane, M.; McGinnity, P. (2014), Anthropocene environmental change in an internationally important oligotrophic catchment on the Atlantic seaboard of western Europe, Anthropocene, 5: 9-21 Foley, S.F.; Gronenborn, D

  13. Detection of Potential Induced Degradation in c-Si PV Panels Using Electrical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Oprea, Matei-lon; Spataru, Sergiu; Sera, Dezso

    2016-01-01

    This work, for the first time, investigates an Impedance Spectroscopy (IS) based method for detecting potential-induced degradation (PID) in crystalline silicon photovoltaic (c-Si PV) panels. The method has been experimentally tested on a set of panels that were confirmed to be affected by PID...

  14. Automated Data Collection for Determining Statistical Distributions of Module Power Undergoing Potential-Induced Degradation

    DEFF Research Database (Denmark)

    Hacke, Peter; Spataru, Sergiu

    We propose a method for increasing the frequency of data collection and reducing the time and cost of accelerated lifetime testing of photovoltaic modules undergoing potential-induced degradation (PID). This consists of in-situ measurements of dark current-voltage curves of the modules at elevate...

  15. On the mechanisms of the radiation-induced degradation of cellulosic substances

    Science.gov (United States)

    Tissot, Chanel; Grdanovska, Slavica; Barkatt, Aaron; Silverman, Joseph; Al-Sheikhly, Mohamad

    2013-03-01

    Much interest has been generated in utilizing ionizing radiation for the production of bio-fuels from cellulosic plant materials. It is well known that exposure of cellulose to ionizing radiation causes significant breakdown of the polysaccharide. Radiation-induced degradation of cellulose may reduce or replace ecologically hazardous chemical steps in addition to reducing the number of processing stages and decreasing energy consumption.

  16. H2O2-induced higher order chromatin degradation: A novel ...

    Indian Academy of Sciences (India)

    Unknown

    mediator of oxidative stress, can also cause genomic damage indirectly. Thus, H2O2 at pathologically relevant concentrations rapidly induces higher order chromatin degradation (HOCD), i.e. enzymatic ... clease works through a single strand scission mechanism ... a great mutagenic risk to the surviving cells, because en-.

  17. A highly uniform ZnO/NaTaO{sub 3} nanocomposite: Enhanced self-sensitized degradation of colored pollutants under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Guanjie; Tang, Changhe [School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia, 010021 (China); Zhang, Bo [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei, 430072 (China); Zhao, Lanxiao; Su, Yiguo [School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia, 010021 (China); Wang, Xiaojing, E-mail: wang_xiao_jing@hotmail.com [School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia, 010021 (China)

    2015-10-25

    In this study, a highly uniform ZnO/NaTaO{sub 3} composite was prepared via simple hydrothermal synthesis. XRD confirmed the composite was constructed by pure cubic phase of NaTaO{sub 3} and hexagonal phase of ZnO. SEM analysis showed that as-prepared ZnO/NaTaO{sub 3} shaped as an irregular ginger with an obviously smaller size than that of pure ZnO without obvious agglomeration. EDS mapping demonstrated that the four elements (Na, Ta, O, Zn) in the composite were very uniformly distributed. The photocatalytic behaviors of as-prepared composites were studied in the degradation of methylene blue both under UV and visible irradiation. The bare ZnO showed the highest activity with 99.8% methylene blue (MB) photodegraded in 70 min under UV light irradiation whereas 94% photodegraded rate was achieved for ZnO/NaTaO{sub 3}. More importantly, the uniform composite of ZnO/NaTaO{sub 3} exhibited effective degradation of methylene blue under visible light which can be attributed to the well dyes adsorption abilities and the high efficiency of electron separation, induced by the synergistic effect between ZnO and NaTaO{sub 3}. It is confirmed the dye rather than a semiconductor is excited under visible light irradiation and a self-sensitized photocatalytic mechanism was then proposed based on the experimental results. - Graphical abstract: Visible light photocatalytic activity of ZnO/NaTaO{sub 3} and proposed schematic of self-sensitization directed photogradation of MB. - Highlights: • Highly uniform ZnO/NaTaO{sub 3} photocatalysts were fabricated by hydrothermal method. • ZnO/NaTaO{sub 3} composite exhibited effective degradation of MB under visible light. • ZnO/NaTaO{sub 3} composite effectively promoted dye adsorption and electrons separation. • A self-sensitized photocatalytic mechanism was proposed for the degradation of dye.

  18. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    Science.gov (United States)

    Vaidya, S. J.; Sharma, D. K.; Shaikh, A. M.; Chandorkar, A. N.

    2002-09-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co 60 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radiation performance of pyrogenic field oxides with respect to positive charge build up as well as interface state generation. Pyrogenic oxide nitrided in N 2O is found to be the best oxynitride as damage due to neutrons is the least.

  19. Gamma and proton induced degradation in ceramics materials - A proposal

    International Nuclear Information System (INIS)

    Constantinescu, B.

    2001-01-01

    Ceramic materials will play very important roles in developing fusion reactors, where they will be used under heavy irradiation environments (neutrons, gamma-rays, protons, helium and other ions) for substantial periods for the first time. The programme at the Institute of Atomic Physics in Bucharest forms a part of the on going ceramics programmes to assess the suitability of SiO2 based materials for both diagnostic and remote handling application. The authors' proposal focuses on comparison of the ionization and displacement induced damage (influence on the UV and visible optical transmission properties) and on radiation enhanced hydrogen isotope diffusion in these materials; the work is performed in cooperation with CIEMAT Madrid and SCK/CEN Mol. The irradiation facilities are: IRASM - 200 kCi Co-60 source, minimum 2kGy/h, ethanol chlorine benzene and ESR dosimetry; HVEC 8 MV TANDEM - protons up to 16 MeV and 200 nA; and 600 kV DISKTRON - H isotopes up to 600 keV, tens of microamperes. (author)

  20. Qualitative and quantitative analysis of light hydrocarbons produced by radiation degradation of N, N-dimethyl hydroxylamine

    International Nuclear Information System (INIS)

    Wang Jinhua; Bao Borong; Wu Minghong; Sun Xilian; Zhang Xianye; Hu Jingxin; Ye Guoan

    2004-01-01

    This paper reports the qualitative and quantitative analysis of light hydrocarbons produced by radiation degradation of N, N-dimethyl hydroxylamine. These analyses were performed on the gas chromatograph, in which porous layer open tubular column coated with aluminum oxide and flame-ionization detector are used. For the doses between 10 and 1000 kGy, the light hydrocarbons produced by radiation degradation of N,N-dimethyl hydroxylamine are methane, ethane, ethene, propane, propene and n-butane. When the concentration of N,N-dimethyl hydroxylamine is 0.2 mol/L, the volume fraction of methane is (9.996-247.5) x 10 -6 , the volume fraction of ethane, propane and n-butane is lower and that of ethene and propene is much lower. With the increase of dose the volume fraction of methane is increased but the volume fraction of ethane, ethene, propane, propene and n-butane is not obviously changed. (authors)

  1. Monitoring the Erosion of Hydrolytically-Degradable Nanogels via Multiangle Light Scattering Coupled to Asymmetrical Flow Field-Flow Fractionation

    Science.gov (United States)

    Smith, Michael H.; South, Antoinette B.; Gaulding, Jeffrey C.; Lyon, L. Andrew

    2009-01-01

    We describe the synthesis and characterization of degradable nanogels that display bulk erosion under physiologic conditions (pH = 7.4, 37 °C). Erodible poly(N-isopropylmethacrylamide) nanogels were synthesized by copolymerization with N,O-(dimethacryloyl)hydroxylamine, a cross-linker previously used in the preparation of non-toxic and biodegradable bulk hydrogels. To monitor particle degradation, we employed multiangle light scattering and differential refractometry detection following asymmetrical flow field-flow fractionation. This approach allowed the detection of changes in nanogel molar mass and topology as a function of both temperature and pH. Particle erosion was evident from both an increase in nanogel swelling and a decrease in scattering intensity as a function of time. Following these analyses, the samples were recovered for subsequent characterization by direct particle tracking, which yields hydrodynamic size measurements and enables number density determination. Additionally, we confirmed the conservation of nanogel stimuli-responsivity through turbidity measurements. Thus, we have demonstrated the synthesis of degradable nanogels that erode under conditions and on timescales that are relevant for many drug delivery applications. The combined separation and light scattering detection method is demonstrated to be a versatile means to monitor erosion and should also find applicability in the characterization of other degradable particle constructs. PMID:20000662

  2. SrTiO3 Nanocube-Doped Polyaniline Nanocomposites with Enhanced Photocatalytic Degradation of Methylene Blue under Visible Light

    Directory of Open Access Journals (Sweden)

    Syed Shahabuddin

    2016-02-01

    Full Text Available The present study highlights the facile synthesis of polyaniline (PANI-based nanocomposites doped with SrTiO3 nanocubes synthesized via the in situ oxidative polymerization technique using ammonium persulfate (APS as an oxidant in acidic medium for the photocatalytic degradation of methylene blue dye. Field emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM, thermogravimetric analysis (TGA, X-ray diffraction (XRD, UV–Vis spectroscopy, Brunauer–Emmett–Teller analysis (BET and Fourier transform infrared spectroscopy (FTIR measurements were used to characterize the prepared nanocomposite photocatalysts. The photocatalytic efficiencies of the photocatalysts were examined by degrading methylene blue (MB under visible light irradiation. The results showed that the degradation efficiency of the composite photocatalysts that were doped with SrTiO3 nanocubes was higher than that of the undoped polyaniline. In this study, the effects of the weight ratio of polyaniline to SrTiO3 on the photocatalytic activities were investigated. The results revealed that the nanocomposite P-Sr500 was found to be an optimum photocatalyst, with a 97% degradation efficiency after 90 min of irradiation under solar light.

  3. Plasma-Induced Degradation of Polypropene Plastics in Natural Volatile Constituents of Ledum palustre Herb

    International Nuclear Information System (INIS)

    Yu Hong; Yu Shenjing; Xiu Zhilong; Ren Chunsheng

    2012-01-01

    Polypropene (PP) plastics can be effectively degraded by natural volatile constituents from Ledum palustre catalyzed by atmospheric air dielectric barrier (DBD) plasma. The electron spin resonance (ESR) result indicates that the volatile constituents produce radicals in aerobic condition energized by power sources such as light, UV, plasma and so on. The degradation is a novel chemically oxidative way and it is initiated by a series of radical reactions. Lots of active and oxidative species, radicals, products and high energy electromagnetic field in plasma aggravate the degradation process. The results about PP maximum tensile strength (σ bmax ) confirm this conclusion. PP plastic heavily loses its extensibility, mechanical integrity and strength in a short time after suffering a synergetic treatment of the herb extract and air DBD plasma with no toxic residues left. The components of herb extract keep almost unchanged and may be reused. This study offers a new approach to manage and recycle typical plastics.

  4. Wind Erosion Induced Soil Degradation in Northern China: Status, Measures and Perspective

    Directory of Open Access Journals (Sweden)

    Zhongling Guo

    2014-12-01

    Full Text Available Soil degradation is one of the most serious ecological problems in the world. In arid and semi-arid northern China, soil degradation predominantly arises from wind erosion. Trends in soil degradation caused by wind erosion in northern China frequently change with human activities and climatic change. To decrease soil loss by wind erosion and enhance local ecosystems, the Chinese government has been encouraging residents to reduce wind-induced soil degradation through a series of national policies and several ecological projects, such as the Natural Forest Protection Program, the National Action Program to Combat Desertification, the “Three Norths” Shelter Forest System, the Beijing-Tianjin Sand Source Control Engineering Project, and the Grain for Green Project. All these were implemented a number of decades ago, and have thus created many land management practices and control techniques across different landscapes. These measures include conservation tillage, windbreak networks, checkerboard barriers, the Non-Watering and Tube-Protecting Planting Technique, afforestation, grassland enclosures, etc. As a result, the aeolian degradation of land has been controlled in many regions of arid and semiarid northern China. However, the challenge of mitigating and further reversing soil degradation caused by wind erosion still remains.

  5. Potential-induced degradation of Cu(In,Ga)Se2 photovoltaic modules

    Science.gov (United States)

    Yamaguchi, Seira; Jonai, Sachiko; Hara, Kohjiro; Komaki, Hironori; Shimizu-Kamikawa, Yukiko; Shibata, Hajime; Niki, Shigeru; Kawakami, Yuji; Masuda, Atsushi

    2015-08-01

    Potential-induced degradation (PID) of Cu(In,Ga)Se2 (CIGS) photovoltaic (PV) modules fabricated from integrated submodules is investigated. PID tests were performed by applying a voltage of -1000 V to connected submodule interconnector ribbons at 85 °C. The normalized energy conversion efficiency of a standard module decreases to 0.2 after the PID test for 14 days. This reveals that CIGS modules suffer PID under this experimental condition. In contrast, a module with non-alkali glass shows no degradation, which implies that the degradation occurs owing to alkali metal ions, e.g., Na+, migrating from the cover glass. The results of dynamic secondary ion mass spectrometry show Na accumulation in the n-ZnO transparent conductive oxide layer of the degraded module. A CIGS PV module with an ionomer (IO) encapsulant instead of a copolymer of ethylene and vinyl acetate shows no degradation. This reveals that the IO encapsulant can prevent PID of CIGS modules. A degraded module can recover from its performance losses by applying +1000 V to connected submodule interconnector ribbons from an Al plate placed on the test module.

  6. Crystallization-mediated amorphous Cu_xO (x = 1, 2)/crystalline CuI p–p type heterojunctions with visible light enhanced and ultraviolet light restrained photocatalytic dye degradation performance

    International Nuclear Information System (INIS)

    Wang, Hongli; Cai, Yun; Zhou, Jian; Fang, Jun; Yang, Yang

    2017-01-01

    Highlights: • Cu_xO(x = 1, 2)/CuI p–p type heterojunctions were facilely constructed via crystallization-mediated approaches. • Cu_xO/CuI heterojunctions exhibit effective visible-light-driven photocatalytic activity for dye degradation. • The Cu_xO/CuI interface can enhance the spatial separation of the photogenerated electron–hole pairs. • This work represents a critical step for mass production of functional semiconductor heterojunctions in a mild manner. - Abstract: We report simple and cost-effective fabrication of amorphous Cu_xO (x = 1, 2)/crystalline CuI p–p type heterojunctions based on crystallization-mediated approaches including antisolvent crystallization and crystal reconstruction. Starting from CuI acetonitrile solution, large crystals in commercial CuI can be easily converted to aggregates consisting of small particles by the crystallization processes while the spontaneous oxidation of CuI by atmospheric/dissolved oxygen can induce the formation of trace Cu_xO on CuI surface. As a proof of concept, the as-fabricated Cu_xO/CuI heterojunctions exhibit effective photocatalytic activity towards the degradation of methyl blue and other organic pollutants under visible light irradiation, although the wide band-gap semiconductor CuI is insensible to visible light. Unexpectedly, the Cu_xO/CuI heterojunctions exhibit restrained photocatalytic activity when ultraviolet light is applied in addition to the visible. It is suggested that the Cu_xO/CuI interface can enhance the spatial separation of the electron–hole pairs with the excitation of Cu_xO under visible light and prolong the lifetime of photogenerated charges with high redox ability. The present work represents a critically important step in advancing the crystallization technique for potential mass production of semiconductor heterojunctions in a mild manner.

  7. Lead induced changes in phosphorylation of PSII proteins in low light grown pea plants.

    Science.gov (United States)

    Wioleta, Wasilewska; Anna, Drożak; Ilona, Bacławska; Kamila, Kąkol; Elżbieta, Romanowska

    2015-02-01

    Light-intensity and redox-state induced thylakoid proteins phosphorylation involved in structural changes and in regulation of protein turnover. The presence of heavy metal ions triggers a wide range of cellular responses including changes in plant growth and photosynthesis. Plants have evolved a number of mechanisms to protect photosynthetic apparatus. We have characterized the effect of lead on PSII protein phosphorylation in pea (Pisum sativum L.) plants grown in low light conditions. Pb ions affected only slightly photochemical efficiency of PSII and had no effect on organization of thylakoid complexes. Lead activated strongly phosphorylation of PSII core D1 protein and dephosphorylation of this protein did not proceed in far red light. D1 protein was also not degraded in this conditions. However, phosphorylation of LHCII proteins was not affected by lead. These results indicate that Pb(2+) stimulate the phosphorylation of PSII core proteins and by disturbing the disassembly of supercomplexes play a role in PSII repair mechanism. LHCII phosphorylation could control the distribution of energy between the photosystems in low light conditions. This demonstrates that plants may respond to heavy metals by induction different pathways responsible for protein protection under stress conditions.

  8. Light-induced oxidative stress, N-formylkynurenine, and oxygenic photosynthesis.

    Directory of Open Access Journals (Sweden)

    Tina M Dreaden Kasson

    Full Text Available Light stress in plants results in damage to the water oxidizing reaction center, photosystem II (PSII. Redox signaling, through oxidative modification of amino acid side chains, has been proposed to participate in this process, but the oxidative signals have not yet been identified. Previously, we described an oxidative modification, N-formylkynurenine (NFK, of W365 in the CP43 subunit. The yield of this modification increases under light stress conditions, in parallel with the decrease in oxygen evolving activity. In this work, we show that this modification, NFK365-CP43, is present in thylakoid membranes and may be formed by reactive oxygen species produced at the Mn(4CaO(5 cluster in the oxygen-evolving complex. NFK accumulation correlates with the extent of photoinhibition in PSII and thylakoid membranes. A modest increase in ionic strength inhibits NFK365-CP43 formation, and leads to accumulation of a new, light-induced NFK modification (NFK317 in the D1 polypeptide. Western analysis shows that D1 degradation and oligomerization occur under both sets of conditions. The NFK modifications in CP43 and D1 are found 17 and 14 Angstrom from the Mn(4CaO(5 cluster, respectively. Based on these results, we propose that NFK is an oxidative modification that signals for damage and repair in PSII. The data suggest a two pathway model for light stress responses. These pathways involve differential, specific, oxidative modification of the CP43 or D1 polypeptides.

  9. Photo-degradation of clofibric acid by ultraviolet light irradiation at 185 nm.

    Science.gov (United States)

    Li, Wenzhen; Lu, Shuguang; Chen, Nuo; Gu, Xiaogang; Qiu, Zhaofu; Fan, Ji; Lin, Kuangfei

    2009-01-01

    As a metabolite of lipid regulators, clofibric acid (CA) was investigated in this study for its ultraviolet (UV) degradation at monochromatic wavelength of 185 nm using Milli-Q water and sewage treatment plant (STP) effluent. The effects of CA initial concentration, solution pH, humic acid (HA), nitrate and bicarbonate anions on CA degradation performances were evaluated. All CA degradation patterns well fitted the pseudo-first-order kinetic model. The results showed that OH generated from water photolysis by UV185 irradiation was involved, resulting in indirect CA photolysis but contributed less to the whole CA removal when compared to the main direct photolysis process. Acid condition favored slightly to CA degradation and other constituents in solution, such as HA (5.0-100.0 mg L(-1)), nitrate and bicarbonate anions (1.0x10(-3) mol L(-1) and 0.1 mol L(-1)), had negative effects on CA degradation. When using real STP effluent CA degradation could reach 97.4% (without filtration) and 99.3% (with filtration) after 1 hr irradiation, showing its potential mean in pharmaceuticals removal in UV disinfection unit. Mineralization tests showed that rapid chloride ion release happened, resulting in no chlorinated intermediates accumulation, and those non-chlorinated intermediate products could further be nearly completely degraded to CO2 and H2O after 6 hrs.

  10. GRP94 Regulates Circulating Cholesterol Levels through Blockade of PCSK9-Induced LDLR Degradation

    Directory of Open Access Journals (Sweden)

    Steve Poirier

    2015-12-01

    Full Text Available Clearance of circulating low-density lipoprotein cholesterol (LDLc by hepatic LDL receptors (LDLR is central for vascular health. Secreted by hepatocytes, PCSK9 induces the degradation of LDLR, resulting in higher plasma LDLc levels. Still, it remains unknown why LDLR and PCSK9 co-exist within the secretory pathway of hepatocytes without leading to complete degradation of LDLR. Herein, we identified the ER-resident GRP94, and more precisely its client-binding C-terminal domain, as a PCSK9-LDLR inhibitory binding protein. Depletion of GRP94 did not affect calcium homeostasis, induce ER stress, nor did it alter PCSK9 processing or its secretion but greatly increased its capacity to induce LDLR degradation. Accordingly, we found that hepatocyte-specific Grp94-deficient mice have higher plasma LDLc levels correlated with ∼80% reduction in hepatic LDLR protein levels. Thus, we provide evidence that, in physiological conditions, binding of PCSK9 to GRP94 protects LDLR from degradation likely by preventing early binding of PCSK9 to LDLR within the ER.

  11. Total-dose radiation-induced degradation of thin film ferroelectric capacitors

    International Nuclear Information System (INIS)

    Schwank, J.R.; Nasby, R.D.; Miller, S.L.; Rodgers, M.S.; Dressendorfer, P.V.

    1990-01-01

    Thin film PbZr y Ti 1-y O 3 (PZT) ferroelectric memories offer the potential for radiation-hardened, high-speed nonvolatile memories with good retention and fatigue properties. In this paper we explore in detail the radiation hardness of PZT ferroelectric capacitors. Ferroelectric capacitors were irradiated using x-ray and Co-60 sources to dose levels up to 16 Mrad(Si). The capacitors were characterized for their memory properties both before and after irradiation. The radiation hardness was process dependent. Three out of four processes resulted in capacitors that showed less than 30% radiation-induced degradation in retained polarization charge and remanent polarization after irradiating to 16 Mrad(Si). On the other hand, one of the processes showed significant radiation-induced degradation in retained polarization charge and remanent polarization at dose levels above 1 Mrad(Si). The decrease in retained polarization charge appears to be due to an alteration of the switching characteristics of the ferroelectric due to changes in the internal fields. The radiation-induced degradation is recoverable by a postirradiation biased anneal and can be prevented entirely if devices are cycled during irradiation. The authors have developed a model to simulate the observed degradation

  12. Light-Induced Switching of Tunable Single-Molecule Junctions

    KAUST Repository

    Sendler, Torsten

    2015-04-16

    A major goal of molecular electronics is the development and implementation of devices such as single-molecular switches. Here, measurements are presented that show the controlled in situ switching of diarylethene molecules from their nonconductive to conductive state in contact to gold nanoelectrodes via controlled light irradiation. Both the conductance and the quantum yield for switching of these molecules are within a range making the molecules suitable for actual devices. The conductance of the molecular junctions in the opened and closed states is characterized and the molecular level E 0, which dominates the current transport in the closed state, and its level broadening Γ are identified. The obtained results show a clear light-induced ring forming isomerization of the single-molecule junctions. Electron withdrawing side-groups lead to a reduction of conductance, but do not influence the efficiency of the switching mechanism. Quantum chemical calculations of the light-induced switching processes correlate these observations with the fundamentally different low-lying electronic states of the opened and closed forms and their comparably small modification by electron-withdrawing substituents. This full characterization of a molecular switch operated in a molecular junction is an important step toward the development of real molecular electronics devices.

  13. Light-Induced Switching of Tunable Single-Molecule Junctions

    KAUST Repository

    Sendler, Torsten; Luka-Guth, Katharina; Wieser, Matthias; Lokamani; Wolf, Jannic Sebastian; Helm, Manfred; Gemming, Sibylle; Kerbusch, Jochen; Scheer, Elke; Huhn, Thomas; Erbe, Artur

    2015-01-01

    A major goal of molecular electronics is the development and implementation of devices such as single-molecular switches. Here, measurements are presented that show the controlled in situ switching of diarylethene molecules from their nonconductive to conductive state in contact to gold nanoelectrodes via controlled light irradiation. Both the conductance and the quantum yield for switching of these molecules are within a range making the molecules suitable for actual devices. The conductance of the molecular junctions in the opened and closed states is characterized and the molecular level E 0, which dominates the current transport in the closed state, and its level broadening Γ are identified. The obtained results show a clear light-induced ring forming isomerization of the single-molecule junctions. Electron withdrawing side-groups lead to a reduction of conductance, but do not influence the efficiency of the switching mechanism. Quantum chemical calculations of the light-induced switching processes correlate these observations with the fundamentally different low-lying electronic states of the opened and closed forms and their comparably small modification by electron-withdrawing substituents. This full characterization of a molecular switch operated in a molecular junction is an important step toward the development of real molecular electronics devices.

  14. Factors influencing the efficiency of radiation-induced degradation of water pollutants

    International Nuclear Information System (INIS)

    Getoff, Nikola

    2002-01-01

    The efficiency of the radiation-induced degradation of water pollutants depends on several factors, such as kind and energy of radiation, absorbed dose, dose rate, pollutant concentration as well as synergistic effects of radiation and ozone or/and catalysts (e.g. TiO 2 ) and of the molecular structure of the pollutants. The role of the individual factors is illustrated by examples. The application of pulse radiolysis in addition to chemical analysis for elucidation of reaction mechanisms and optimization of the degradation treatment is also mentioned

  15. Charge collection efficiency degradation induced by MeV ions in semiconductor devices: Model and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Vittone, E., E-mail: ettore.vittone@unito.it [Department of Physics, NIS Research Centre and CNISM, University of Torino, via P. Giuria 1, 10125 Torino (Italy); Pastuovic, Z. [Centre for Accelerator Science (ANSTO), Locked bag 2001, Kirrawee DC, NSW 2234 (Australia); Breese, M.B.H. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Garcia Lopez, J. [Centro Nacional de Aceleradores (CNA), Sevilla University, J. Andalucia, CSIC, Av. Thomas A. Edison 7, 41092 Sevilla (Spain); Jaksic, M. [Department for Experimental Physics, Ruder Boškovic Institute (RBI), P.O. Box 180, 10002 Zagreb (Croatia); Raisanen, J. [Department of Physics, University of Helsinki, Helsinki 00014 (Finland); Siegele, R. [Centre for Accelerator Science (ANSTO), Locked bag 2001, Kirrawee DC, NSW 2234 (Australia); Simon, A. [International Atomic Energy Agency (IAEA), Vienna International Centre, P.O. Box 100, 1400 Vienna (Austria); Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Vizkelethy, G. [Sandia National Laboratories (SNL), PO Box 5800, Albuquerque, NM (United States)

    2016-04-01

    Highlights: • We study the electronic degradation of semiconductors induced by ion irradiation. • The experimental protocol is based on MeV ion microbeam irradiation. • The radiation induced damage is measured by IBIC. • The general model fits the experimental data in the low level damage regime. • Key parameters relevant to the intrinsic radiation hardness are extracted. - Abstract: This paper investigates both theoretically and experimentally the charge collection efficiency (CCE) degradation in silicon diodes induced by energetic ions. Ion Beam Induced Charge (IBIC) measurements carried out on n- and p-type silicon diodes which were previously irradiated with MeV He ions show evidence that the CCE degradation does not only depend on the mass, energy and fluence of the damaging ion, but also depends on the ion probe species and on the polarization state of the device. A general one-dimensional model is derived, which accounts for the ion-induced defect distribution, the ionization profile of the probing ion and the charge induction mechanism. Using the ionizing and non-ionizing energy loss profiles resulting from simulations based on the binary collision approximation and on the electrostatic/transport parameters of the diode under study as input, the model is able to accurately reproduce the experimental CCE degradation curves without introducing any phenomenological additional term or formula. Although limited to low level of damage, the model is quite general, including the displacement damage approach as a special case and can be applied to any semiconductor device. It provides a method to measure the capture coefficients of the radiation induced recombination centres. They can be considered indexes, which can contribute to assessing the relative radiation hardness of semiconductor materials.

  16. Chemically induced and light-independent cryptochrome photoreceptor activation.

    Science.gov (United States)

    Rosenfeldt, Gesa; Viana, Rafael Muñoz; Mootz, Henning D; von Arnim, Albrecht G; Batschauer, Alfred

    2008-01-01

    The cryptochrome photoreceptors of higher plants are dimeric proteins. Their N-terminal photosensory domain mediates dimerization, and the unique C-terminal extension (CCT) mediates signaling. We made use of the human FK506-binding protein (FKBP) that binds with high affinity to rapamycin or rapamycin analogs (rapalogs). The FKBP-rapamycin complex is recognized by another protein, FRB, thus allowing rapamycin-induced dimerization of two target proteins. Here we demonstrate by bioluminescence resonance energy transfer (BRET) assays the applicability of this regulated dimerization system to plants. Furthermore, we show that fusion proteins consisting of the C-terminal domain of Arabidopsis cryptochrome 2 fused to FKBP and FRB and coexpressed in Arabidopsis cells specifically induce the expression of cryptochrome-controlled reporter and endogenous genes in darkness upon incubation with the rapalog. These results demonstrate that the activation of cryptochrome signal transduction can be chemically induced in a dose-dependent fashion and uncoupled from the light signal, and provide the groundwork for gain-of-function experiments to study specifically the role of photoreceptors in darkness or in signaling cross-talk even under light conditions that activate members of all photoreceptor families.

  17. Desolvation Induced Origami of Photocurable Polymers by Digit Light Processing.

    Science.gov (United States)

    Zhao, Zeang; Wu, Jiangtao; Mu, Xiaoming; Chen, Haosen; Qi, H Jerry; Fang, Daining

    2017-07-01

    Self-folding origami is of great interest in current research on functional materials and structures, but there is still a challenge to develop a simple method to create freestanding, reversible, and complex origami structures. This communication provides a feasible solution to this challenge by developing a method based on the digit light processing technique and desolvation-induced self-folding. In this new method, flat polymer sheets can be cured by a light field from a commercial projector with varying intensity, and the self-folding process is triggered by desolvation in water. Folded origami structures can be recovered once immersed in the swelling medium. The self-folding process is investigated both experimentally and theoretically. Diverse 3D origami shapes are demonstrated. This method can be used for responsive actuators and the fabrication of 3D electronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Visible light photoelectrocatalysis with salicylic acid-modified TiO2 nanotube array electrode for p-nitrophenol degradation

    International Nuclear Information System (INIS)

    Wang Xin; Zhao Huimin; Quan Xie; Zhao Yazhi; Chen Shuo

    2009-01-01

    This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO 2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO 2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO 2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV-vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO 2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79-100% under visible light (λ > 400 nm), compared with TiO 2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO 2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.

  19. Upgrading of highly elapsed degradation damage evaluation of structural materials for the light water reactors

    International Nuclear Information System (INIS)

    Katada, Yasuyuki; Matsushima, Shinobu; Sato, Shunji

    1998-01-01

    In this study, for degradation of structural materials in accompanying with highly yearly lapse of the nuclear power plants, it was an aim to elucidate interaction between material degradation and degradation under high hot water environment. And, another aims consisted in intention of expansion protection and recovery evaluation of damage due to laser processing method and so on for welded portion showing extreme material degradation and in preparation of damage region diagram based on the obtained data. In this fiscal year, on interaction between materials and environmental degradation, it was found that as stress corrosion cracking of materials hardened by shot peening shows a resemble shapes of stress-strain curve in CERT and CLRT, shapes of load-time curve were much different. On comparison of the SP material and non-processing material, as peak current showing activity of newly created surface shows no difference, re-passivation of the SP material was found to be too late. And, on recovery evaluation of material degradation damage, as it was found that constant melt depth was essential to evaluate corrosion, a condition preparation aimed for melt depth of more than 1 mm. As only small amount of bubbles were observed at molten metal part on YAG laser processing, it was found that many small bubbles scatter at thermal effect part. (G.K.)

  20. Light induces petal color change in Quisqualis indica (Combretaceae

    Directory of Open Access Journals (Sweden)

    Juan Yan

    2018-02-01

    Full Text Available Petal color change, a common phenomenon in angiosperms, is induced by various environmental and endogenous factors. Interestingly, this phenomenon is important for attracting pollinators and further reproductive success. Quisqualis indica L. (Combretaceae is a tropical Asian climber that undergoes sequential petal color change from white to pink to red. This color changing process is thought to be a good strategy to attract more pollinators. However, the underlying physiological and biochemical mechanisms driving this petal color change phenomenon is still underexplored. In this context, we investigated whether changes in pH, pollination, light, temperature or ethylene mediate petal color change. We found that the detected changes in petal pH were not significant enough to induce color alterations. Additionally, pollination and temperatures of 20–30 °C did not alter the rate of petal color change; however, flowers did not open when exposed to constant temperatures at 15 °C or 35 °C. Moreover, the application of ethylene inhibitor, i.e., silver thiosulphate, did not prevent color change. It is worth mentioning here that in our study we found light as a strong factor influencing the whole process of petal color change, as petals remained white under dark conditions. Altogether, the present study suggests that petal color change in Q. indica is induced by light and not by changes in petal pH, pollination, ethylene, or temperature, while extremely low or high temperatures affect flower anthesis. In summary, our findings represent the probable mechanism underlying the phenomenon of petal color change, which is important for understanding flower color evolution.

  1. Soft-type trap-induced degradation of MoS2 field effect transistors

    Science.gov (United States)

    Cho, Young-Hoon; Ryu, Min-Yeul; Lee, Kook Jin; Park, So Jeong; Choi, Jun Hee; Lee, Byung-Chul; Kim, Wungyeon; Kim, Gyu-Tae

    2018-06-01

    The practical applicability of electronic devices is largely determined by the reliability of field effect transistors (FETs), necessitating constant searches for new and better-performing semiconductors. We investigated the stress-induced degradation of MoS2 multilayer FETs, revealing a steady decrease of drain current by 56% from the initial value after 30 min. The drain current recovers to the initial state when the transistor is completely turned off, indicating the roles of soft-traps in the apparent degradation. The noise current power spectrum follows the model of carrier number fluctuation–correlated mobility fluctuation (CNF–CMF) regardless of stress time. However, the reduction of the drain current was well fitted to the increase of the trap density based on the CNF–CMF model, attributing the presence of the soft-type traps of dielectric oxides to the degradation of the MoS2 FETs.

  2. Protection of a protein against irradiation-induced degradation by additives in the solid state

    International Nuclear Information System (INIS)

    Shalaev, E.; Reddy, R.; Kimball, R.N.; Weinschenk, M.F.; Guinn, M.; Margulis, L.

    2003-01-01

    The impact of ionizing radiation on a globular protein (porcine somatotropin, pST) in the solid state was studied using rate of dissolution, high-performance liquid chromatography, and Electron spin resonance (ESR) in the presence of different additives. o-Vanillin stabilized pST against irradiation-induced degradation whereas effects of trolox and isopropyl alcohol were less significant. Stabilization effect of o-vanillin has been related to the energy transfer from pST molecules to the additive which was facilitated by formation of covalent bonds between o-vanillin and pST molecules. Anticorrelation between the level of free radicals and chemical degradation (i.e. degradation increased with decrease in a free radical level) was observed in the presence of o-vanillin

  3. Gut microbial degradation of organophosphate insecticides-induces glucose intolerance via gluconeogenesis.

    Science.gov (United States)

    Velmurugan, Ganesan; Ramprasath, Tharmarajan; Swaminathan, Krishnan; Mithieux, Gilles; Rajendhran, Jeyaprakash; Dhivakar, Mani; Parthasarathy, Ayothi; Babu, D D Venkatesh; Thumburaj, Leishman John; Freddy, Allen J; Dinakaran, Vasudevan; Puhari, Shanavas Syed Mohamed; Rekha, Balakrishnan; Christy, Yacob Jenifer; Anusha, Sivakumar; Divya, Ganesan; Suganya, Kannan; Meganathan, Boominathan; Kalyanaraman, Narayanan; Vasudevan, Varadaraj; Kamaraj, Raju; Karthik, Maruthan; Jeyakumar, Balakrishnan; Abhishek, Albert; Paul, Eldho; Pushpanathan, Muthuirulan; Rajmohan, Rajamani Koushick; Velayutham, Kumaravel; Lyon, Alexander R; Ramasamy, Subbiah

    2017-01-24

    Organophosphates are the most frequently and largely applied insecticide in the world due to their biodegradable nature. Gut microbes were shown to degrade organophosphates and cause intestinal dysfunction. The diabetogenic nature of organophosphates was recently reported but the underlying molecular mechanism is unclear. We aimed to understand the role of gut microbiota in organophosphate-induced hyperglycemia and to unravel the molecular mechanism behind this process. Here we demonstrate a high prevalence of diabetes among people directly exposed to organophosphates in rural India (n = 3080). Correlation and linear regression analysis reveal a strong association between plasma organophosphate residues and HbA1c but no association with acetylcholine esterase was noticed. Chronic treatment of mice with organophosphate for 180 days confirms the induction of glucose intolerance with no significant change in acetylcholine esterase. Further fecal transplantation and culture transplantation experiments confirm the involvement of gut microbiota in organophosphate-induced glucose intolerance. Intestinal metatranscriptomic and host metabolomic analyses reveal that gut microbial organophosphate degradation produces short chain fatty acids like acetic acid, which induces gluconeogenesis and thereby accounts for glucose intolerance. Plasma organophosphate residues are positively correlated with fecal esterase activity and acetate level of human diabetes. Collectively, our results implicate gluconeogenesis as the key mechanism behind organophosphate-induced hyperglycemia, mediated by the organophosphate-degrading potential of gut microbiota. This study reveals the gut microbiome-mediated diabetogenic nature of organophosphates and hence that the usage of these insecticides should be reconsidered.

  4. Light-induced metastable structural changes in hydrogenated amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Fritzsche, H. [Univ. of Chicago, IL (United States)

    1996-09-01

    Light-induced defects (LID) in hydrogenated amorphous silicon (a-Si:H) and its alloys limit the ultimate efficiency of solar panels made with these materials. This paper reviews a variety of attempts to find the origin of and to eliminate the processes that give rise to LIDs. These attempts include novel deposition processes and the reduction of impurities. Material improvements achieved over the past decade are associated more with the material`s microstructure than with eliminating LIDs. We conclude that metastable LIDs are a natural by-product of structural changes which are generally associated with non-radiative electron-hole recombination in amorphous semiconductors.

  5. The synthesis of hierarchical nanostructured MoS_2/Graphene composites with enhanced visible-light photo-degradation property

    International Nuclear Information System (INIS)

    Zhao, Yongjie; Zhang, Xiaowei; Wang, Chengzhi; Zhao, Yuzhen; Zhou, Heping; Li, Jingbo; Jin, HaiBo

    2017-01-01

    Graphical abstract: Introducing graphene layer into MoS_2 could construct the steady hierarchical structure which could efficiently separate the photo-induced electrons so as to enhance the photo- degradation behavior. - Highlights: • The MoS_2 and MoS_2/Graphene nanocomposite have been synthesized via a solvothermal process. • The scrolled nanosheets of MoS_2 combining with interconnected graphene network promoted the formation of steady hierarchical architecture. • Comparing with MoS_2, the hierarchical MoS_2/Graphene nanocomposite achieved relatively higher degradation rate. • The synergistic effect mechanism for excellent photo-degradation activity was proposed. - Abstract: Novel two-dimensional materials with a layered structure are of special interest for a variety of promising applications. Herein, MoS_2 and MoS_2/Graphene nanocomposite with hierarchical nanostructure were successfully synthesized employing a one-step hydrothermal method. Photo-degradation of methylene blue (MB) and rhodamine (RHB) were adopted to assess the photo-degradation ability of the products. Comparing with bare MoS_2, the hierarchical MoS_2/Graphene nanocomposite achieved relatively higher degradation rate of 99% in 28 min for MB as well in 50 min for RHB. These results verified that this proposed hierarchical nanocomposite is a good photo-degradation semiconductor. The excellent performance was mainly ascribed to the synergistic effect of MoS_2 and graphene layers. The MoS_2 possessing a band gap of 1.9 eV would provide abundant electron-hole pairs. The graphene layers with excellent electro-conductivity could realize the quick transport of electrons via its extended π-conjugation structure, consequently benefiting the separation of photo-generated carriers. These findings indicate that the graphene layer is a promising candidate as a co-catalyst for MoS_2 photo-catalyst, and also provide useful information for understanding the observed enhanced photocatalytic mechanism

  6. Microwave-induced carbon nanotubes catalytic degradation of organic pollutants in aqueous solution

    International Nuclear Information System (INIS)

    Chen, Jing; Xue, Shuang; Song, Youtao; Shen, Manli; Zhang, Zhaohong; Yuan, Tianxin; Tian, Fangyuan; Dionysiou, Dionysios D.

    2016-01-01

    Highlights: • Microwave-induced CNTs-based catalytic degradation technology is developed. • Microwave catalytic activities of CNTs with different diameters are compared. • Organic pollutants with different structure can be degraded in MW/CNTs system. • The 10–20 nm CNTs shows the higher catalytic activity under MW irradiation. - Abstract: In this study, a new catalytic degradation technology using microwave induced carbon nanotubes (MW/CNTs) was proposed and applied in the treatment of organic pollutants in aqueous solution. The catalytic activity of three CNTs of 10–20 nm, 20–40 nm, and 40–60 nm diameters were compared. The results showed that organic pollutants such as methyl orange (MO), methyl parathion (MP), sodium dodecyl benzene sulfonate (SDBS), bisphenol A (BPA), and methylene blue (MB) in aqueous solution could be degraded effectively and rapidly in MW/CNTs system. CNTs with diameter of 10–20 nm exhibited the highest catalytic activity of the three CNTs under MW irradiation. Further, complete degradation was obtained using 10–20 nm CNTs within 7.0 min irradiation when 25 mL MO solution (25 mg/L), 1.2 g/L catalyst dose, 450 W, 2450 MHz, and pH = 6.0 were applied. The rate constants (k) for the degradation of SDBS, MB, MP, MO and BPA using 10–20 nm CNTs/MW system were 0.726, 0.679, 0.463, 0.334 and 0.168 min"−"1, respectively. Therefore, this technology may have potential application for the treatment of targeted organic pollutants in wastewaters.

  7. Microwave-induced carbon nanotubes catalytic degradation of organic pollutants in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing; Xue, Shuang; Song, Youtao; Shen, Manli [School of Environment Science, Liaoning University, Shenyang 110036 (China); Zhang, Zhaohong, E-mail: lnuhjhx@163.com [School of Environment Science, Liaoning University, Shenyang 110036 (China); Yuan, Tianxin; Tian, Fangyuan [School of Environment Science, Liaoning University, Shenyang 110036 (China); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States)

    2016-06-05

    Highlights: • Microwave-induced CNTs-based catalytic degradation technology is developed. • Microwave catalytic activities of CNTs with different diameters are compared. • Organic pollutants with different structure can be degraded in MW/CNTs system. • The 10–20 nm CNTs shows the higher catalytic activity under MW irradiation. - Abstract: In this study, a new catalytic degradation technology using microwave induced carbon nanotubes (MW/CNTs) was proposed and applied in the treatment of organic pollutants in aqueous solution. The catalytic activity of three CNTs of 10–20 nm, 20–40 nm, and 40–60 nm diameters were compared. The results showed that organic pollutants such as methyl orange (MO), methyl parathion (MP), sodium dodecyl benzene sulfonate (SDBS), bisphenol A (BPA), and methylene blue (MB) in aqueous solution could be degraded effectively and rapidly in MW/CNTs system. CNTs with diameter of 10–20 nm exhibited the highest catalytic activity of the three CNTs under MW irradiation. Further, complete degradation was obtained using 10–20 nm CNTs within 7.0 min irradiation when 25 mL MO solution (25 mg/L), 1.2 g/L catalyst dose, 450 W, 2450 MHz, and pH = 6.0 were applied. The rate constants (k) for the degradation of SDBS, MB, MP, MO and BPA using 10–20 nm CNTs/MW system were 0.726, 0.679, 0.463, 0.334 and 0.168 min{sup −1}, respectively. Therefore, this technology may have potential application for the treatment of targeted organic pollutants in wastewaters.

  8. Ultraviolet light-induced suppression of antigen presentation

    International Nuclear Information System (INIS)

    Spellman, C.W.; Tomasi, T.B.

    1983-01-01

    Ultraviolet (UV) light irradiation of animals results in the development of specific T suppressor cells that inhibit antitumor immune responses. It is thought that suppression may arise as a consequence of altered antigen presentation by UV-irradiated epidermal cells. This hypothesis is based on evidence demonstrating that specific lymphoid tissues from UV-irradiated hosts exhibit impaired antigen-presenting function and that animals cannot be contact sensitized when antigens are applied to a UV-irradiated skin site. Langerhans cells of the skin are likely candidates as targets of UV-induced defects in antigen presentation as they bear Fc and C3b receptors, express Ia antigens, are of bone marrow origin, and are capable of presenting antigen in vitro. We speculate on the possible clinical usefulness of UV-induced tolerance to specific antigens such as those encountered in monoclonal antibody therapy and tissue transplantation

  9. Efficient degradation of phenol using iron-montmorillonite as a Fenton catalyst: Importance of visible light irradiation and intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xipeng; Wu, Honghai, E-mail: wuhonghai@scnu.edu.cn; He, Guangping, E-mail: hegp@scnu.edu.cn; Guan, Yufeng

    2017-01-05

    Highlights: • Iron-montmorillonite has excellent catalytic activity on phenol Fenton degradation. • Phenol Fenton reaction follows the two-stage pseudo first order kinetic equations. • Role of visible light irradiation is more evident during induction reaction period. • Hydroquinone and catechol have a significant effect on the second-stage kinetics. - Abstract: Iron-montmorillonite (Fe-Mt) with delaminated structures was synthesized via the introduction of iron oxides into Na-montmorillonite. Fe-Mt showed significant increases in the available iron content, surface area and pore volume, along with a slight increase in the basal spacing from d{sub 001} = 1.26 (Na-Mt) to 1.53 nm (Fe-Mt). The Fenton process was efficient for phenol removal using Fe-Mt as a catalyst under visible light irradiation, and the process had two-stage pseudo-first order kinetics. The overall reaction had a higher degradation rate even when it was only irradiated with visible light for the first 40 min period. Further investigation confirmed that the irradiation increased the presence of certain intermediates. Among them, 1,4-benzoquinone, hydroquinone, and catechol all enhanced the Fenton reaction rates. Either catechol or hydroquinone was added to the Fenton system with Fe-Mt/H{sub 2}O{sub 2} with or without visible light irradiation, and they both accelerated phenol degradation because catechol and hydroquinone are capable of reductively and effectively transforming Fe(III) into Fe(II). The concentrations of dissolved total Fe increased with the increase in the oxalic acid concentration, which can strongly chelate Fe(III). Hence, iron was released from Fe-Mt, and reductive transformation played an important role in promoting the Fenton reaction process for phenol removal.

  10. Ag loaded WO_3 nanoplates for efficient photocatalytic degradation of sulfanilamide and their bactericidal effect under visible light irradiation

    International Nuclear Information System (INIS)

    Zhu, Wenyu; Liu, Jincheng; Yu, Shuyan; Zhou, Yan; Yan, Xiaoli

    2016-01-01

    Highlights: • WO_3/Ag heterogeneous composites were fabricated with simply photo-reduction method. • Property changes due to Ag loading were systematically studied. • WO_3/Ag composites efficiently degraded sulfanilamide under visible light irradiation. • WO_3/Ag composites exhibited bactericidal effectS under visible light irradiation. - Abstract: Sulfonamides (SAs) are extensively used antibiotics and their residues in the water bodies propose potential threat to the public. In this study, degradation efficiency of sulfanilamide (SAM), which is the precursor of SAs, using WO_3 nanoplates and their Ag heterogeneous as photocatalysts was investigated. WO_3 nanoplates with uniform size were synthesized by a facile one step hydrothermal method. Different amount of Ag nanoparticles (Ag NPs) were loaded onto WO_3 nanoplates using a photo-reduction method to generate WO_3/Ag composites. The physio-chemical properties of synthesized nanomaterials were systematically characterized. Photodegradation of SAM by WO_3 and WO_3/Ag composites was conducted under visible light irradiation. The results show that WO_3/Ag composites performed much better than pure WO_3 where the highest removal rate was 96.2% in 5 h. Ag as excellent antibacterial agent also endows certain antibacterial efficiency to WO_3, and 100% removal efficiency against Escherichia Coli and Bacillus subtilis could be achieved in 2 h under visible light irradiation for all three WO_3/Ag composites synthesized. The improved performance in terms of SAM degradation and antibacterial activity of WO_3/Ag can be attributed to the improved electron-hole pair separation rate where Ag NPs act as effective electron trapper during the photocatalytic process.

  11. Efficient degradation of phenol using iron-montmorillonite as a Fenton catalyst: Importance of visible light irradiation and intermediates

    International Nuclear Information System (INIS)

    Wei, Xipeng; Wu, Honghai; He, Guangping; Guan, Yufeng

    2017-01-01

    Highlights: • Iron-montmorillonite has excellent catalytic activity on phenol Fenton degradation. • Phenol Fenton reaction follows the two-stage pseudo first order kinetic equations. • Role of visible light irradiation is more evident during induction reaction period. • Hydroquinone and catechol have a significant effect on the second-stage kinetics. - Abstract: Iron-montmorillonite (Fe-Mt) with delaminated structures was synthesized via the introduction of iron oxides into Na-montmorillonite. Fe-Mt showed significant increases in the available iron content, surface area and pore volume, along with a slight increase in the basal spacing from d_0_0_1 = 1.26 (Na-Mt) to 1.53 nm (Fe-Mt). The Fenton process was efficient for phenol removal using Fe-Mt as a catalyst under visible light irradiation, and the process had two-stage pseudo-first order kinetics. The overall reaction had a higher degradation rate even when it was only irradiated with visible light for the first 40 min period. Further investigation confirmed that the irradiation increased the presence of certain intermediates. Among them, 1,4-benzoquinone, hydroquinone, and catechol all enhanced the Fenton reaction rates. Either catechol or hydroquinone was added to the Fenton system with Fe-Mt/H_2O_2 with or without visible light irradiation, and they both accelerated phenol degradation because catechol and hydroquinone are capable of reductively and effectively transforming Fe(III) into Fe(II). The concentrations of dissolved total Fe increased with the increase in the oxalic acid concentration, which can strongly chelate Fe(III). Hence, iron was released from Fe-Mt, and reductive transformation played an important role in promoting the Fenton reaction process for phenol removal.

  12. Crystallization-mediated amorphous CuxO (x = 1, 2)/crystalline CuI p-p type heterojunctions with visible light enhanced and ultraviolet light restrained photocatalytic dye degradation performance

    Science.gov (United States)

    Wang, Hongli; Cai, Yun; Zhou, Jian; Fang, Jun; Yang, Yang

    2017-04-01

    We report simple and cost-effective fabrication of amorphous CuxO (x = 1, 2)/crystalline CuI p-p type heterojunctions based on crystallization-mediated approaches including antisolvent crystallization and crystal reconstruction. Starting from CuI acetonitrile solution, large crystals in commercial CuI can be easily converted to aggregates consisting of small particles by the crystallization processes while the spontaneous oxidation of CuI by atmospheric/dissolved oxygen can induce the formation of trace CuxO on CuI surface. As a proof of concept, the as-fabricated CuxO/CuI heterojunctions exhibit effective photocatalytic activity towards the degradation of methyl blue and other organic pollutants under visible light irradiation, although the wide band-gap semiconductor CuI is insensible to visible light. Unexpectedly, the CuxO/CuI heterojunctions exhibit restrained photocatalytic activity when ultraviolet light is applied in addition to the visible. It is suggested that the CuxO/CuI interface can enhance the spatial separation of the electron-hole pairs with the excitation of CuxO under visible light and prolong the lifetime of photogenerated charges with high redox ability. The present work represents a critically important step in advancing the crystallization technique for potential mass production of semiconductor heterojunctions in a mild manner.

  13. Immobilized/P25/DSAT and Immobilized/Kronos/DSAT on Photocatalytic Degradation of Reactive Red 4 Under Fluorescent Light

    Directory of Open Access Journals (Sweden)

    Azami M. S.

    2016-01-01

    Full Text Available In this work, photocatalytic degradation of Reactive Red 4 (RR4 using immobilized P25 and kronos were performed under fluorescent light sources. The photocatalysis activity for both catalysts was investigated under fluorescent lamp source which consist UV and Visible light. The effect of various parameters such as initial concentration, initial pH and strenght of immobilized plate were studied. The result showed that 90% of RR4 dye was degrade in 1 hr using immobilized/kronos/DSAT at 100 mg L-1 of RR4 dye while 81% degradation was achieved by immobilized/P25/DSAT at the same condition. The lowest pH showed the higher photocatalytic activity. Hence, the effect of dye concentration and pH on the photocatalysis study can be related with the behavior of environmental pollution. The low strength showed by immobilized/P25/DSAT where it remain 37 % as compared with strength of immobilized/kronos/DSAT (52 wt.%. For the future work, the polymer binder like Polyvinyl alcohol (PVA, Polyethylene glycol (PEG, and others polymers can be apply in immobilized study to overcome the strength problem.

  14. The influence of battery degradation level on the selected traction parameters of a light-duty electric vehicle

    Science.gov (United States)

    Juda, Z.; Noga, M.

    2016-09-01

    The article describes results of an analysis of the impact of degradation level of battery made in lead-acid technology on selected traction parameters of an electric light duty vehicle. Lead-acid batteries are still used in these types of vehicles. They do not require complex systems of performance management and monitoring and are easy to maintaining. Despite the basic disadvantage, which is the low value of energy density, low price is a decisive factor for their use in low-speed electric vehicles. The process of aging of the battery related with an increase in internal resistance of the cells and the loss of electric capacity of the battery was considered. A simplified model of cooperation of the DC electric motor with the battery assuming increased internal resistance was presented. In the paper the results of comparative traction research of the light-duty vehicle equipped with a set of new batteries and set of batteries having a significant degradation level were showed. The analysis of obtained results showed that the correct exploitation of the battery can slow down the processes of degradation and, thus, extend battery life cycle.

  15. Remarkable photo-catalytic degradation of malachite green by nickel doped bismuth selenide under visible light irradiation

    Science.gov (United States)

    Kulsi, Chiranjit; Ghosh, Amrita; Mondal, Anup; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

    2017-01-01

    Bismuth selenide (Bi2Se3) and nickel (Ni) doped Bi2Se3 were prepared by a solvothermal approach to explore the photo-catalytic performance of the materials in degradation of malachite green (MG). The presence of nickel was confirmed by X-ray photoelectron spectroscopy (XPS) measurement in doped Bi2Se3. The results showed that the nickel doping played an important role in microstructure and photo-catalytic activity of the samples. Nickel doped Bi2Se3 sample exhibited higher photo-catalytic activity than that of the pure Bi2Se3 sample under visible-light irradiation. The photo-catalytic degradation followed first-order reaction kinetics. Fast degradation kinetics and complete (100% in 5 min of visible light irradiation) removal of MG was achieved by nickel doped Bi2Se3 in presence of hydrogen peroxide (H2O2) due to modification of band gap energies leading to suppression of photo-generated electron-hole recombination.

  16. Photocatalytic behaviour of CdS/ZnS nanocomposite for dye degradation in presence of visible light

    Energy Technology Data Exchange (ETDEWEB)

    Patil, B. N. [Department of Physics, Shri Datta Meghe Polytechnic, Nagpur, M.S. (India); Acharya, S. A., E-mail: saha275@yahoo.com [Department of Physics, Rastrasant Tukdoji Maharaj Nagpur University, Nagpur-440033 (India)

    2016-05-06

    In the present work ZnS-CdS composite was prepared by hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD) to confirm formation of nano particles, Scanning electron microscopy (SEM) images exhibit nanoscale dimensions of as synthesized individual phases. UV/VIS spectra were recorded for evaluation of photophysical properties. The composite was explored as photocatalysts to study dye degradation using methylene blue in aqueous slurry under irradiation of 663 nm wavelength and congo red under irradiation of 493 nm wavelength. Under the same conditions the photocatalytic activity of the individual phases ZnS and CdS were also examined. The ZnS-CdS composite is found in enhancing the rate of photo degradation of toxic dyes as compare to ZnS and CdS individually in presence of visible light. This ZnS based metal sulphide/oxide semiconductor nanocomposites are high potential material for Photo-degradation of toxic dyes, and act as good photocatalyst in visible light.

  17. Atomic diffusion induced degradation in bimetallic layer coated cemented tungsten carbide

    International Nuclear Information System (INIS)

    Peng, Zirong; Rohwerder, Michael; Choi, Pyuck-Pa; Gault, Baptiste; Meiners, Thorsten; Friedrichs, Marcel; Kreilkamp, Holger; Klocke, Fritz; Raabe, Dierk

    2017-01-01

    Highlights: • We study the temporal degradation of PtIr/Cr/WC and PtIr/Ni/WC systems. • Short cut diffusion, segregation, oxidation and interdiffusion reactions occurred. • Outward diffusion of Cr (Ni) via PtIr grain boundaries triggered the degradation. • The microstructure of the PtIr layer controlled the systems stability. • We propose an atomic diffusion induced degradation mechanism. - Abstract: We investigated the temporal degradation of glass moulding dies, made of cemented tungsten carbide coated with PtIr on an adhesive Cr or Ni interlayer, by electron microscopy and atom probe tomography. During the exposure treatments at 630 °C under an oxygen partial pressure of 1.12 × 10"−"2"3 bar, Cr (Ni) was found to diffuse outwards via grain boundaries in the PtIr, altering the surface morphology. Upon dissolution of the interlayer, the WC substrate also started degrading. Extensive interdiffusion processes involving PtIr, Cr (Ni) and WC took place, leading to the formation of intermetallic phases and voids, deteriorating the adhesion of the coating.

  18. Automated Data Collection for Determining Statistical Distributions of Module Power Undergoing Potential-Induced Degradation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, P.; Spataru, S.

    2014-08-01

    We propose a method for increasing the frequency of data collection and reducing the time and cost of accelerated lifetime testing of photovoltaic modules undergoing potential-induced degradation (PID). This consists of in-situ measurements of dark current-voltage curves of the modules at elevated stress temperature, their use to determine the maximum power at 25 degrees C standard test conditions (STC), and distribution statistics for determining degradation rates as a function of stress level. The semi-continuous data obtained by this method clearly show degradation curves of the maximum power, including an incubation phase, rates and extent of degradation, precise time to failure, and partial recovery. Stress tests were performed on crystalline silicon modules at 85% relative humidity and 60 degrees C, 72 degrees C, and 85 degrees C. Activation energy for the mean time to failure (1% relative) of 0.85 eV was determined and a mean time to failure of 8,000 h at 25 degrees C and 85% relative humidity is predicted. No clear trend in maximum degradation as a function of stress temperature was observed.

  19. Dark electrical bias effect on moisture-induced degradation in inverted lead halide perovskite solar cells measured by advanced chemical probes

    KAUST Repository

    Barbe, Jeremy; Kumar, Vikas; Newman, Michael; Lee, Harrison; Jain, Sagar Motilal; Chen, Hu; Charbonneau, Cé cile; Rodenburg, C; Tsoi, Wing

    2018-01-01

    Emerging lead halide perovskite materials have enormous potential for a range of optoelectronic devices, such as solar cells, light emitting diodes, transistors and lasers. However, the large-scale commercialization of these technologies will depend on the ability of the active material to be stable under environmental and operating conditions. In this work, we measured the first time the electrical bias-induced degradation of inverted perovskite solar cells in the dark in different environments and concluded that humidity coupled with electrical bias results in fast degradation of CH3NH3PbI3 into PbI2. Micro-Raman and photoluminescence show that the degradation starts from the edge of the cell due to moisture ingress. By using novel local Raman-transient photocurrent measurements, we were able to probe local ion migration at the degraded region and non-degraded region and found that the formation of PbI2 can passivate perovskite by reducing ion migration. The degradation is far from uniform across different grains as revealed by secondary electron hyperspectral imaging, an advanced scanning electron microscopy technique which allows probing the composition of individual grain from the cross-section. By using potential step chronoamperometry, we also found that the bias degradation is closely related to the density of mobile ions. The unique combination of established methods with several novel analytical tools provides an insight into the origin of the bias-degradation of inverted perovskite solar cells from nano-scale to cell level, and demonstrates the potential of these novel tools for studying the degradation in other perovskite systems.

  20. Dark electrical bias effect on moisture-induced degradation in inverted lead halide perovskite solar cells measured by advanced chemical probes

    KAUST Repository

    Barbe, Jeremy

    2018-02-12

    Emerging lead halide perovskite materials have enormous potential for a range of optoelectronic devices, such as solar cells, light emitting diodes, transistors and lasers. However, the large-scale commercialization of these technologies will depend on the ability of the active material to be stable under environmental and operating conditions. In this work, we measured the first time the electrical bias-induced degradation of inverted perovskite solar cells in the dark in different environments and concluded that humidity coupled with electrical bias results in fast degradation of CH3NH3PbI3 into PbI2. Micro-Raman and photoluminescence show that the degradation starts from the edge of the cell due to moisture ingress. By using novel local Raman-transient photocurrent measurements, we were able to probe local ion migration at the degraded region and non-degraded region and found that the formation of PbI2 can passivate perovskite by reducing ion migration. The degradation is far from uniform across different grains as revealed by secondary electron hyperspectral imaging, an advanced scanning electron microscopy technique which allows probing the composition of individual grain from the cross-section. By using potential step chronoamperometry, we also found that the bias degradation is closely related to the density of mobile ions. The unique combination of established methods with several novel analytical tools provides an insight into the origin of the bias-degradation of inverted perovskite solar cells from nano-scale to cell level, and demonstrates the potential of these novel tools for studying the degradation in other perovskite systems.

  1. Photocatalytic degradation of indigo carmine by ZnO photocatalyst under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Ali Al- Taie

    2017-09-01

    Full Text Available In this work, the photocatalytic degradation of indigo carmine (IC using zinc oxide suspension was studied. The effect of influential parameters such as initial indigo carmine concentration and catalyst loading were studied with the effect of Vis irradiation in the presence of reused ZnO was also investigated. The increased in initial dye concentration decreased the photodegradation and the increased catalyst loading increased the degradation percentage and the reused-ZnO exhibits lower photocatalytic activity than the ZnO catalyst. It has been found that the photocatalytic degradation of indigo carmine obeyed the pseudo-first-order kinetic reaction in presence of zinc oxide. This was found from plotting the relationship between ln (C0/Ct and irradiation the rate constant of the process.UV- spectrophotometer was used to study the indigo carmine photodegradation

  2. Transient light-induced intracellular oxidation revealed by redox biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Kolossov, Vladimir L., E-mail: viadimer@illinois.edu [Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801 (United States); Beaudoin, Jessica N. [Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801 (United States); Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207 W. Gregory Drive, Urbana, IL 61801 (United States); Hanafin, William P. [Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801 (United States); DiLiberto, Stephen J. [Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801 (United States); Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207 W. Gregory Drive, Urbana, IL 61801 (United States); Kenis, Paul J.A. [Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801 (United States); Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801 (United States); Rex Gaskins, H. [Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W. Gregory Drive, Urbana, IL 61801 (United States); Department of Animal Sciences, University of Illinois at Urbana-Champaign, 1207 W. Gregory Drive, Urbana, IL 61801 (United States); Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 S. Lincoln Avenue, Urbana, IL 61801 (United States); Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, 905 S. Goodwin Avenue, Urbana, IL 61801 (United States)

    2013-10-04

    Highlights: •Time-resolved live cell imaging revealed light-induced oxidation. •Only the roGFP probe fused with glutaredoxin reveals photooxidation. •The transient oxidation is rapidly reduced by the cytosolic antioxidant system. •Intracellular photooxidation is media-dependent. •Oxidation is triggered exclusively by exposure to short wavelength excitation. -- Abstract: We have implemented a ratiometric, genetically encoded redox-sensitive green fluorescent protein fused to human glutaredoxin (Grx1-roGFP2) to monitor real time intracellular glutathione redox potentials of mammalian cells. This probe enabled detection of media-dependent oxidation of the cytosol triggered by short wavelength excitation. The transient nature of light-induced oxidation was revealed by time-lapse live cell imaging when time intervals of less than 30 s were implemented. In contrast, transient ROS generation was not observed with the parental roGFP2 probe without Grx1, which exhibits slower thiol-disulfide exchange. These data demonstrate that the enhanced sensitivity of the Grx1-roGFP2 fusion protein enables the detection of short-lived ROS in living cells. The superior sensitivity of Grx1-roGFP2, however, also enhances responsiveness to environmental cues introducing a greater likelihood of false positive results during image acquisition.

  3. Transient light-induced intracellular oxidation revealed by redox biosensor

    International Nuclear Information System (INIS)

    Kolossov, Vladimir L.; Beaudoin, Jessica N.; Hanafin, William P.; DiLiberto, Stephen J.; Kenis, Paul J.A.; Rex Gaskins, H.

    2013-01-01

    Highlights: •Time-resolved live cell imaging revealed light-induced oxidation. •Only the roGFP probe fused with glutaredoxin reveals photooxidation. •The transient oxidation is rapidly reduced by the cytosolic antioxidant system. •Intracellular photooxidation is media-dependent. •Oxidation is triggered exclusively by exposure to short wavelength excitation. -- Abstract: We have implemented a ratiometric, genetically encoded redox-sensitive green fluorescent protein fused to human glutaredoxin (Grx1-roGFP2) to monitor real time intracellular glutathione redox potentials of mammalian cells. This probe enabled detection of media-dependent oxidation of the cytosol triggered by short wavelength excitation. The transient nature of light-induced oxidation was revealed by time-lapse live cell imaging when time intervals of less than 30 s were implemented. In contrast, transient ROS generation was not observed with the parental roGFP2 probe without Grx1, which exhibits slower thiol-disulfide exchange. These data demonstrate that the enhanced sensitivity of the Grx1-roGFP2 fusion protein enables the detection of short-lived ROS in living cells. The superior sensitivity of Grx1-roGFP2, however, also enhances responsiveness to environmental cues introducing a greater likelihood of false positive results during image acquisition

  4. Visible-light-induced photocatalysis of low-level methyl-tertiary butyl ether (MTBE) and trichloroethylene (TCE) using element-doped titanium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Wan-Kuen; Yang, Chang-Hee [Department of Environmental Engineering, Kyungpook National University, Sankeokdong, Bukgu, Daegu 702-701 (Korea)

    2010-04-15

    While the photocatalytic degradation of various volatile organic compounds in conjunction with UV light has been widely reported, visible-light-induced photocatalytic degradation of low-levels of the pollutants MTBE and TCE, which have been linked to potential adverse health effects, is rarely reported. The present study examined whether visible-light-activated S- or N-doped TiO{sub 2} photocatalytic technology can be used to control indoor concentrations of MTBE and TCE. This study consists of the characterization of the doped TiO{sub 2} powders, as well as an investigation of their photocatalytic activities. In regards to both powders, a shift of the absorbance spectrum towards the visible light region was observed. An activity test suggested that these photocatalysts exhibited reasonably high degradation efficiencies towards MTBE and TCE under visible light irradiation. The degradation efficiencies of MTBE and TCE by S- and N-doped photocatalysts exceeded 75 and 80%, respectively, at input concentrations (IC) of 0.1 ppm. Degradation efficiency was dependent on both IC and relative humidity. TCE could enhance the degradation efficiency of MTBE even under visible-light irradiation. The estimated mineralization efficiencies (MEs) were comparable to those of previous studies conducted with UV/TiO{sub 2} systems. Similar to the relative degradation efficiencies, the ME of TCE was higher in comparison to that of MTBE. The CO production measured during the photocatalytic processes represented a negligible addition to indoor CO levels. These results suggest that visible-light-activated S- and N-doped TiO{sub 2} photocatalysts may prove a useful tool in the effort to improve indoor air quality. (author)

  5. Fabrication of Ag{sub 2}O/TiO{sub 2} with enhanced photocatalytic performances for dye pollutants degradation by a pH-induced method

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Hai-Tao, E-mail: renhaitaomail@163.com; Yang, Qing

    2017-02-28

    Highlights: • Ag{sub 2}O/TiO{sub 2} was synthesized by a pH-induced chemical precipitation method. • Ag{sub 2}O/TiO{sub 2} showed good activities in the photocatalytic degradation of methyl orange. • Hydroxyl radicals played the predominant role in methyl orange photodegradation. - Abstract: Ag{sub 2}O/TiO{sub 2} composites synthesized in this study were applied into the photocatalytic degradation of methyl orange (MO) under UV and visible light irradiation. X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscope analysis demonstrated that Ag{sub 2}O nanoparticles were well distributed on the surface of TiO{sub 2} and the heterostructure of Ag{sub 2}O/TiO{sub 2} was formed. Compared with the pure TiO{sub 2} and Ag{sub 2}O, the 3% and 50% Ag{sub 2}O/TiO{sub 2} composite displayed much higher photocatalytic activities in MO degradation under UV and visible light irradiation, respectively. The degradation rate constant of 50% composite was 0.01508 min{sup −1} under visible light, which was almost 20.1 and 1.2 times more than that of the pure TiO{sub 2} and Ag{sub 2}O, respectively. Moreover, the formation of Ag(0) on the surface of Ag{sub 2}O under illumination contributed to the high stability of Ag{sub 2}O/TiO{sub 2} photocatalysts. It was also found that hydroxyl radicals during the photocatalytic process played the predominant role in MO degradation. The enhanced photochemical activities were attributed to the formation of the heterostructure between Ag{sub 2}O and TiO{sub 2}, the strong visible light absorption and the high separation efficiency of photogenerated electron–hole pairs resulted from the highly dispersed Ag{sub 2}O particles.

  6. Oxygen- and water-induced degradation of an inverted polymer solar cell: the barrier effect

    DEFF Research Database (Denmark)

    Vesterager Madsen, Morten; Norrman, Kion; Krebs, Frederik C

    2011-01-01

    The work focuses on the degradation of performance induced by both water and oxygen in an inverted geometry organic photovoltaic device with emphasis on the accumulated barrier effect of the layers comprising the layer stack. By studying the exchange of oxygen in the zinc oxide (ZnO) layer...... in the humid atmosphere, correlating well with a long observed lifetime in the same atmosphere.© 2011 Society of Photo-Optical Instrumentation Engineers....

  7. Enhanced tolerance to stretch-induced performance degradation of stretchable MnO2-based supercapacitors.

    Science.gov (United States)

    Huang, Yan; Huang, Yang; Meng, Wenjun; Zhu, Minshen; Xue, Hongtao; Lee, Chun-Sing; Zhi, Chunyi

    2015-02-04

    The performance of many stretchable electronics, such as energy storage devices and strain sensors, is highly limited by the structural breakdown arising from the stretch imposed. In this article, we focus on a detailed study on materials matching between functional materials and their conductive substrate, as well as enhancement of the tolerance to stretch-induced performance degradation of stretchable supercapacitors, which are essential for the design of a stretchable device. It is revealed that, being widely utilized as the electrode material of the stretchable supercapacitor, metal oxides such as MnO2 nanosheets have serious strain-induced performance degradation due to their rigid structure. In comparison, with conducting polymers like a polypyrrole (PPy) film as the electrochemically active material, the performance of stretchable supercapacitors can be well preserved under strain. Therefore, a smart design is to combine PPy with MnO2 nanosheets to achieve enhanced tolerance to strain-induced performance degradation of MnO2-based supercapacitors, which is realized by fabricating an electrode of PPy-penetrated MnO2 nanosheets. The composite electrodes exhibit a remarkable enhanced tolerance to strain-induced performance degradation with well-preserved performance over 93% under strain. The detailed morphology and electrochemical impedance variations are investigated for the mechanism analyses. Our work presents a systematic investigation on the selection and matching of electrode materials for stretchable supercapacitors to achieve high performance and great tolerance to strain, which may guide the selection of functional materials and their substrate materials for the next-generation of stretchable electronics.

  8. Radiation induced electrical degradation in crystalline Al2O3: a bulk effect

    International Nuclear Information System (INIS)

    Zong Xiangfu; Chen, Y.; Evans, B.D.; Gonzalez, R.; Sellers, C.H.

    1995-01-01

    Kesternich et al. and Jung et al. have recently raised serious questions as to whether past investigations of permanent radiation induced electrical degradation (RIED) of ceramics were actually monitoring bulk effects, as claimed. Their evidence to the contrary appears compelling. The present investigation provides evidence that bulk damage does exist and is in the form of dislocations. Discussions are focussed on some aspects of the controversy between evidence for RIED, as reported in the past, and evidence for radiation enhanced surface contaminations. ((orig.))

  9. Activity of cell wall degrading glycanases in methyl jasmonate-induced leaf abscission in Kalanchoe blossfeldiana

    OpenAIRE

    Marian Saniewski; Ewa Gajewska; Henryk Urbanek

    2013-01-01

    It was found previously that methyl jasmonate (JA-Me) induced leaf abscission in Kalanchoe blossfeldiana. In present studies it was shown that JA-Me markedly increased the total activities of cellulase, polygalacturonase, pectinase and xylanase in petioles, but did not affect activities of these enzymes in the blades and apical part of shoots of K. blossfeldiana. These results suggest that methyl jasmonate promotes the degradation of cell wall polysaccharides in the abscission zone and in thi...

  10. Disruption of cortical integration during midazolam-induced light sedation.

    Science.gov (United States)

    Liang, Peipeng; Zhang, Han; Xu, Yachao; Jia, Wenbin; Zang, Yufeng; Li, Kuncheng

    2015-11-01

    This work examines the effect of midazolam-induced light sedation on intrinsic functional connectivity of human brain, using a randomized, double-blind, placebo-controlled, cross-over, within-subject design. Fourteen healthy young subjects were enrolled and midazolam (0.03 mg/kg of the participant's body mass, to a maximum of 2.5 mg) or saline were administrated with an interval of one week. Resting-state fMRI was conducted before and after administration for each subject. We focus on two types of networks: sensory related lower-level functional networks and higher-order functions related ones. Independent component analysis (ICA) was used to identify these resting-state functional networks. We hypothesize that the sensory (visual, auditory, and sensorimotor) related networks will be intact under midazolam-induced light sedation while the higher-order (default mode, executive control, salience networks, etc.) networks will be functionally disconnected. It was found that the functional integrity of the lower-level networks was maintained, while that of the higher-level networks was significantly disrupted by light sedation. The within-network connectivity of the two types of networks was differently affected in terms of direction and extent. These findings provide direct evidence that higher-order cognitive functions including memory, attention, executive function, and language were impaired prior to lower-level sensory responses during sedation. Our result also lends support to the information integration model of consciousness. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

  11. Fabrication of a magnetic nanocomposite photocatalysts Fe3O4@ZIF-67 for degradation of dyes in water under visible light irradiation

    Science.gov (United States)

    Guan, Weihua; Gao, Xuechuan; Ji, Guanfeng; Xing, Yongxing; Du, Chunfang; Liu, Zhiliang

    2017-11-01

    As organic dyes are a major group of water pollutants, the development of materials for the removal of dyes is of great significance for the environment. Here, a novel flower-like Fe3O4@ZIF-67 photocatalyst was synthesized using a simple method at room temperature. It was found that the Fe3O4@ZIF-67 exhibited the ability of degrading Congo red (CR) quickly under visible light irradiation in a short time after adsorption equilibrium. Free radical trapping experiments revealed that the photo-induced active species superoxide radical (•O2-) and holes (h+) were the predominant active species in the photocatalytic system. In addition, results demonstrated that the Fe3O4@ZIF-67 can be magnetically recycled, and maintain high photocatalytic activity after reuse over five cycles with no obvious decrease in the removal efficiency. It suggested that the synthesized material had a potentially promising application for CR removal from waste water.

  12. Visible light driven photocatalytic degradation of methylene blue using novel camphor sulfonic acid doped polycarbazole/g-C3N4 nanocomposite

    Science.gov (United States)

    Praveena, P.; Dhanavel, S.; Sangamithirai, D.; Narayanan, V.; Stephen, A.

    2018-04-01

    A novel polycabazole(PCz)/graphitic carbon nitride(g-C3N4) nanocomposite was synthesized via chemical oxidative polymerization method. In the present work, camphor sulfonic acid (CSA) was used as a dopantand ammonium peroxydisulphate (APS) was used as an oxidizing agent. The PCz/g-C3N4 nanocompositewas characterizedusing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and UV-Visible spectroscopy (UV-Vis). The obtained results confirm the successful formation of PCz/g-C3N4 nanocomposite. Visible light induced photocatalytic activity of the novel catalyst was demonstrated using methylene blue as a target pollutant. The results suggestthat PCz/g-C3N4 nanocomposite can be used as an effective catalyst for the degradation of organic pollutants from waste water.

  13. Microwave assisted synthesis of porous ZnO/SnS heterojunction and its application in visible light degradation of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Makama, A. B., E-mail: abmakama@hotmail.com; Salmiaton, A., E-mail: mie@upm.edu.my; Choong, T. S. Y., E-mail: csthomas@upm.edu.my; Abdullah, N., E-mail: nhafizah@upm.edu.my [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, Selangor, Serdang, UPM 43400 (Malaysia); Saion, E. B., E-mail: elias@upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, Selangor, Serdang, UPM 43400 (Malaysia)

    2016-07-06

    Porous ZnO/SnS heterojunctions were successfully synthesized via microwave-assisted heating of aqueous solutions containing different amounts of SnS precursors (SnCl{sub 2} and Na{sub 2}S) in the presence of fixed amount of ZnCO{sub 3} nanoparticles. The experimental results revealed that the heterojunctions exhibited much higher visible light-driven photocatalytic activity for the degradation of the ciprofloxacin than pure SnS nanocrystals. The photocatalytic degradation efficiency (1-C{sub t}/C{sub 0}) of the pollutant for the most active heterogeneous nanostructure is about four times more efficient than pure SnS. The enhanced photocatalytic efficiency is ascribed to the synergic effect of high photon absorption and reduction in the recombination of electrons and holes because of efficient separation and electron transfer from the SnS to ZnO nanoparticles.

  14. PHOTO-CATALYST DEGRADATION OF TARTRAZINE COMPOUND IN WASTEWATER USING TiO2 AND UV LIGHT

    Directory of Open Access Journals (Sweden)

    SALAM K. AL-DAWERY

    2013-12-01

    Full Text Available Organic contaminants present in industrial wastewater are of major concern with respect to the health of the general public. Photo-catalytic process, one of the Advanced Oxidation Processes, is a promising technology for remediation of organic pollutants at ambient conditions. Photo-catalytic processes in the presence of TiO2 provide an interesting method to destroy hazardous organic contaminants. The experimental results showed that considerable degradation of Tartrazine organic compound has been achieved by combination of TiO2 and UV light, the process followed first order kinetics. The results showed that the increased level of TiO2 concentration does not necessarily increase the rate of degradation of organic compounds. Also, it was found that the higher the TiO2 concentrations the higher the pH values and more oscillatory behaviors were observed. Not much effect has been noted on the process due to temperature variation.

  15. Light-induced magnetoresistance in solution-processed planar hybrid devices measured under ambient conditions

    Directory of Open Access Journals (Sweden)

    Sreetama Banerjee

    2017-07-01

    Full Text Available We report light-induced negative organic magnetoresistance (OMAR measured in ambient atmosphere in solution-processed 6,13-bis(triisopropylsilylethynylpentacene (TIPS-pentacene planar hybrid devices with two different device architectures. Hybrid electronic devices with trench-isolated electrodes (HED-TIE having a channel length of ca. 100 nm fabricated in this work and, for comparison, commercially available pre-structured organic field-effect transistor (OFET substrates with a channel length of 20 µm were used. The magnitude of the photocurrent as well as the magnetoresistance was found to be higher for the HED-TIE devices because of the much smaller channel length of these devices compared to the OFETs. We attribute the observed light-induced negative magnetoresistance in TIPS-pentacene to the presence of electron–hole pairs under illumination as the magnetoresistive effect scales with the photocurrent. The magnetoresistance effect was found to diminish over time under ambient conditions compared to a freshly prepared sample. We propose that the much faster degradation of the magnetoresistance effect as compared to the photocurrent was due to the incorporation of water molecules in the TIPS-pentacene film.

  16. Light-induced magnetoresistance in solution-processed planar hybrid devices measured under ambient conditions.

    Science.gov (United States)

    Banerjee, Sreetama; Bülz, Daniel; Reuter, Danny; Hiller, Karla; Zahn, Dietrich R T; Salvan, Georgeta

    2017-01-01

    We report light-induced negative organic magnetoresistance (OMAR) measured in ambient atmosphere in solution-processed 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) planar hybrid devices with two different device architectures. Hybrid electronic devices with trench-isolated electrodes (HED-TIE) having a channel length of ca. 100 nm fabricated in this work and, for comparison, commercially available pre-structured organic field-effect transistor (OFET) substrates with a channel length of 20 µm were used. The magnitude of the photocurrent as well as the magnetoresistance was found to be higher for the HED-TIE devices because of the much smaller channel length of these devices compared to the OFETs. We attribute the observed light-induced negative magnetoresistance in TIPS-pentacene to the presence of electron-hole pairs under illumination as the magnetoresistive effect scales with the photocurrent. The magnetoresistance effect was found to diminish over time under ambient conditions compared to a freshly prepared sample. We propose that the much faster degradation of the magnetoresistance effect as compared to the photocurrent was due to the incorporation of water molecules in the TIPS-pentacene film.

  17. Mass spectrometric comparison of swift heavy ion-induced and anaerobic thermal degradation of polymers

    Science.gov (United States)

    Lima, V.; Hossain, U. H.; Walbert, T.; Seidl, T.; Ensinger, W.

    2018-03-01

    The study of polymers irradiated by highly energetic ions and the resulting radiation-induced degradation is of major importance for space and particle accelerator applications. The mechanism of ion-induced molecular fragmentation of polyethylene, polyethyleneimine and polyamide was investigated by means of mass spectrometry and infrared spectroscopy. The results show that the introduction of nitrogen and oxygen into the polymer influences the stability rendering aliphatic polymers with heteroatoms less stable. A comparison to thermal decomposition data from literature reveals that ion-induced degradation is different in its bond fracture mechanism. While thermal degradation starts at the weakest bond, which is usually the carbon-heteroatom bond, energetic ion irradiation leads in the first step to scission of all types of bonds creating smaller molecular fragments. This is due to the localized extreme energy input under non-equilibrium conditions when the ions transfer kinetic energy onto electrons. These findings are of relevance for the choice of polymers for long-term application in both space and accelerator facilities.

  18. Activity of cell wall degrading glycanases in methyl jasmonate-induced leaf abscission in Kalanchoe blossfeldiana

    Directory of Open Access Journals (Sweden)

    Marian Saniewski

    2013-12-01

    Full Text Available It was found previously that methyl jasmonate (JA-Me induced leaf abscission in Kalanchoe blossfeldiana. In present studies it was shown that JA-Me markedly increased the total activities of cellulase, polygalacturonase, pectinase and xylanase in petioles, but did not affect activities of these enzymes in the blades and apical part of shoots of K. blossfeldiana. These results suggest that methyl jasmonate promotes the degradation of cell wall polysaccharides in the abscission zone and in this way induces leaf abscission in Kalanchoe blossfeldiana.

  19. Proteomic analysis of blue light-induced twining response in Cuscuta australis.

    Science.gov (United States)

    Li, Dongxiao; Wang, Liangjiang; Yang, Xiaopo; Zhang, Guoguang; Chen, Liang

    2010-01-01

    The parasitic plant Cuscuta australis (dodder) invades a variety of species by entwining the stem and leaves of a host and developing haustoria. The twining response prior to haustoria formation is regarded as the first sign for dodders to parasitize host plants, and thus has been the focus of studies on the host-parasite interaction. However, the molecular mechanism is still poorly understood. In the present work, we have investigated the different effects of blue and white light on the twining response, and identified a set of proteins that were differentially expressed in dodder seedlings using a proteomic approach. Approximately 1,800 protein spots were detected on each 2-D gel, and 47 spots with increased or decreased protein levels were selected and analyzed with MALDI-TOF-MS. Peptide mass fingerprints (PMFs) obtained for these spots were used for protein identification through cross-species database searches. The results suggest that the blue light-induced twining response in dodder seedlings may be mediated by proteins involved in light signal transduction, cell wall degradation, cell structure, and metabolism.

  20. Bivariate constant stress degradation model: LED lighting system reliability estimation with two-stage modelling

    NARCIS (Netherlands)

    Sari, J.K.; Newby, M.J.; Brombacher, A.C.; Tang, L.C.

    2009-01-01

    Light-emitting diode (LED) lamp has received great attention as a potential replacement for the more commercially available lighting technology, such as incandescence and fluorescence lamps. LED which is the main component of LED lamp has a very long lifetime. This means that no or very few failures

  1. Styrene–tin (IV) phosphate nanocomposite for photocatalytic degradation of organic dye in presence of visible light

    Energy Technology Data Exchange (ETDEWEB)

    Rathore, Bhim Singh [School of Chemistry, Shoolini University, Solan 173 212, Himachal Pradesh (India); Department of Chemistry, Government P.G. College, Solan 173 212, Himachal Pradesh (India); Pathania, Deepak, E-mail: dpathania74@gmail.com [School of Chemistry, Shoolini University, Solan 173 212, Himachal Pradesh (India)

    2014-09-01

    Highlights: • Styrene–tin (IV) phosphate nanocomposite (ST/TPNC) ion exchanger was chemically prepared by simple sol–gel method at pH 0–1. • ST/TPNC exhibited higher ion exchange capacity as compared to its inorganic component. • ST/TPNC retained about 35.5% of the initial value of ion exchange capacity after heating up to 400 °C. • ST/TPNC was used as efficient photocatalyst for the degradation of MB dye from aqueous system in the presence of solar light. • The pH titrations studies confirmed the monofunctional strong cationic nature of ST/TPNC. - Abstract: Styrene–tin (IV) phosphate nanocomposite (ST/TPNC) ion exchanger was used as efficient photocatalyst for the degradation of methylene blue dye from aqueous system in the presence of solar light. ST/TPNC exhibited a high efficiency in heterogeneous photocatalytic process for the removal of MB from the water system. The degradation efficiency after 2 h illumination was 80%. The degradation of MB follows the pseudo-first-order kinetics with rate constant 0.00702 min{sup −1}. The nanocomposite ion exchanger was explored for its ion exchange capacity, pH titration, elution behavior, elution concentration and distribution coefficient (K{sub d}). ST/TPNC exhibited a higher ion exchange capacity (1.83 meg/g) compared to its inorganic counterpart (0.55 meg/g). ST/TPNC was characterized using some techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and thermogravimetric analysis (TGA)

  2. Retraction: Myostatin Induces Degradation of Sarcomeric Proteins through a Smad3 Signaling Mechanism During Skeletal Muscle Wasting

    Science.gov (United States)

    Lokireddy, Sudarsanareddy; McFarlane, Craig; Ge, Xiaojia; Zhang, Huoming; Sze, Siu Kwan; Sharma, Mridula

    2011-01-01

    Ubiquitination-mediated proteolysis is a hallmark of skeletal muscle wasting manifested in response to negative growth factors, including myostatin. Thus, the characterization of signaling mechanisms that induce the ubiquitination of intracellular and sarcomeric proteins during skeletal muscle wasting is of great importance. We have recently characterized myostatin as a potent negative regulator of myogenesis and further demonstrated that elevated levels of myostatin in circulation results in the up-regulation of the muscle-specific E3 ligases, Atrogin-1 and muscle ring finger protein 1 (MuRF1). However, the exact signaling mechanisms by which myostatin regulates the expression of Atrogin-1 and MuRF1, as well as the proteins targeted for degradation in response to excess myostatin, remain to be elucidated. In this report, we have demonstrated that myostatin signals through Smad3 (mothers against decapentaplegic homolog 3) to activate forkhead box O1 and Atrogin-1 expression, which further promotes the ubiquitination and subsequent proteasome-mediated degradation of critical sarcomeric proteins. Smad3 signaling was dispensable for myostatin-dependent overexpression of MuRF1. Although down-regulation of Atrogin-1 expression rescued approximately 80% of sarcomeric protein loss induced by myostatin, only about 20% rescue was seen when MuRF1 was silenced, implicating that Atrogin-1 is the predominant E3 ligase through which myostatin manifests skeletal muscle wasting. Furthermore, we have highlighted that Atrogin-1 not only associates with myosin heavy and light chain, but it also ubiquitinates these sarcomeric proteins. Based on presented data we propose a model whereby myostatin induces skeletal muscle wasting through targeting sarcomeric proteins via Smad3-mediated up-regulation of Atrogin-1 and forkhead box O1. PMID:21964591

  3. Degradation analysis of thin film photovoltaic modules

    International Nuclear Information System (INIS)

    Radue, C.; Dyk, E.E. van

    2009-01-01

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P MAX ) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 ∼30% and a total degradation of ∼42%. For Si-2 the initial P MAX was 7.93 W, with initial light-induced degradation of ∼10% and a total degradation of ∼17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  4. Degradation analysis of thin film photovoltaic modules

    Energy Technology Data Exchange (ETDEWEB)

    Radue, C., E-mail: chantelle.radue@nmmu.ac.z [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Dyk, E.E. van [Department of Physics, PO Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2009-12-01

    Five thin film photovoltaic modules were deployed outdoors under open circuit conditions after a thorough indoor evaluation. Two technology types were investigated: amorphous silicon (a-Si:H) and copper indium gallium diselenide (CIGS). Two 14 W a-Si:H modules, labelled Si-1 and Si-2, were investigated. Both exhibited degradation, initially due to the well-known light-induced degradation described by Staebler and Wronski [Applied Physics Letters 31 (4) (1977) 292], and thereafter due to other degradation modes such as cell degradation. The various degradation modes contributing to the degradation of the a-Si:H modules will be discussed. The initial maximum power output (P{sub MAX}) of Si-1 was 9.92 W, with the initial light-induced degradation for Si-1 approx30% and a total degradation of approx42%. For Si-2 the initial P{sub MAX} was 7.93 W, with initial light-induced degradation of approx10% and a total degradation of approx17%. Three CIGS modules were investigated: two 20 W modules labelled CIGS-1 and CIGS-2, and a 40 W module labelled CIGS-3. CIGS-2 exhibited stable performance while CIGS-1 and CIGS-3 exhibited degradation. CIGS is known to be stable over long periods of time, and thus the possible reasons for the degradation of the two modules are discussed.

  5. Visible-Light Degradation of Dyes and Phenols over Mesoporous Titania Prepared by Using Anthocyanin from Red Radish as Template

    Directory of Open Access Journals (Sweden)

    Zhiying Yan

    2014-01-01

    Full Text Available Heterogeneous photocatalysis is able to operate effectively to eliminate organic compounds from wastewater in the presence of semiconductor photocatalyst and a light source. Although photosensitization of titania by organic dyes is one of the conventional ways for visible-light utilization of titania, previous studies have not yet addressed the use of natural food coloring agents as templates in the synthesis of mesostructured materials, let alone the simultaneous achievement of highly crystalline mesoscopic framework and visible-light photocatalytic activity. In this work, anthocyanin, a natural pigment from red radish was directly used as template in synthesis of highly crystalline mesoporous titania. The synthesized mesoporous titania samples were characterized by a combination of various physicochemical techniques, such as XRD, SEM, HRTEM, nitrogen adsorption/desorption, and diffuse reflectance UV-Vis. The prepared mesoporous titania photocatalyst exhibited significant activity under visible-light irradiation for the degradation of dyes and phenols due to its red shift of band-gap-absorption onset and visible-light response as a result of the incorporation of surface carbon species.

  6. Enhanced visible light photocatalytic activity of copper-doped titanium oxide–zinc oxide heterojunction for methyl orange degradation

    Energy Technology Data Exchange (ETDEWEB)

    Dorraj, Masoumeh, E-mail: masidor20@gmail.com [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Alizadeh, Mahdi [UM Power Energy Dedicated Advanced Centre (UMPEDAC), Level 4 Wisma R& D, University of Malaya, Jalan Pantai Baharu, 59990 Kuala Lumpur (Malaysia); Sairi, Nor Asrina, E-mail: asrina@um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); University of Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Basirun, Wan Jefrey [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Goh, Boon Tong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Woi, Pei Meng; Alias, Yatimah [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); University of Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2017-08-31

    Highlights: • The novel Cu-TiO{sub 2}/ZnO heterojunction nanocomposite was synthesized for the first time via a two-step process. • The Cu-TiO{sub 2}/ZnO heterostructured nanocomposite exhibited an enhanced visible-light-driven photocatalytic activity for MO degradation. • The heterostructured nanocomposite could be recycled during the degradation of MO in a three-cycle experiment with good stability. - Abstract: A novel Cu-doped TiO{sub 2} coupled with ZnO nanoparticles (Cu-TiO{sub 2}/ZnO) was prepared by sol-gel method and subsequent precipitation for methyl orange (MO) photodegradation under visible light irradiation. The compositions and shapes of the as-prepared Cu-TiO{sub 2}/ZnO nanocomposites were characterized by photoluminescence spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectra and Brunauer–Emmett–Teller adsorption isotherm techniques. The Cu-TiO{sub 2}/ZnO nanocomposites showed considerably higher photocatalytic activity for MO removal from water under visible light irradiation than that of single-doped semiconductors. The effects of Cu-TiO{sub 2} and ZnO mass ratios on the photocatalytic reaction were also studied. A coupling percentage of 30% ZnO exhibited the highest photocatalytic activity. The enhanced photocatalytic activity of the Cu-TiO{sub 2}/ZnO nanocomposites was mainly attributed to heterojunction formation, which allowed the efficient separation of photoinduced electron−hole pairs at the interface. Moreover, these novel nanocomposites could be recycled during MO degradation in a three-cycle experiment without evident deactivation, which is particularly important in environmental applications.

  7. Collision induced light-scattering from gaseous sulphurhexafluoride

    International Nuclear Information System (INIS)

    Pleich, R.

    1983-10-01

    Modern laser technology permits the measurement of collision induced light-scattering spectra from molecular gases at low densities. Measurements of this type provide a test for the separation dependent pair polarizabilities and pair potentials. For this work the octahedral molecule sulphurhexafluoride (SF 6 , point group symmetry 0sub(h)) has been chosen for which the permanent polarizability anisotropy vanishes. For the experiment an argon ion laser in combination with a double grating monochromator and standard photon counting techniques were used. Both the polarized and depolarized scattering cross sections were obtained. The point dipole-induced-dipole (DID) effect is shown to account for the most of the total scattered intensity. At low frequency shifts the line shape of the SF 6 spectrum is dominated by bound dimers, whereas the intermediate frequency range up to 50 cm -1 is well described by a DID free trajectory binary collision model. The high frequency wings are discussed in terms of the collision induced rotational Raman (CIRR) effect and estimates for the dipole-octopole polarizability E are obtained both from the spectral distribution and from the depolarization ratio. It is demonstrated that the hierarchy of effects constituting the CIRR-model converges slowly for large frequency shifts. (Author)

  8. Chemical biology based on target-selective degradation of proteins and carbohydrates using light-activatable organic molecules.

    Science.gov (United States)

    Toshima, Kazunobu

    2013-05-01

    Proteins and carbohydrates play crucial roles in a wide range of biological processes, including serious diseases. The development of novel and innovative methods for selective control of specific proteins and carbohydrates functions has attracted much attention in the field of chemical biology. In this account article, the development of novel chemical tools, which can degrade target proteins and carbohydrates by irradiation with a specific wavelength of light under mild conditions without any additives, is introduced. This novel class of photochemical agents promise bright prospects for finding not only molecular-targeted bioprobes for understanding of the structure-activity relationships of proteins and carbohydrates but also novel therapeutic drugs targeting proteins and carbohydrates.

  9. Visible light induced electron transfer process over nitrogen doped TiO2 nanocrystals prepared by oxidation of titanium nitride

    International Nuclear Information System (INIS)

    Wu Zhongbiao; Dong Fan; Zhao Weirong; Guo Sen

    2008-01-01

    Nitrogen doped TiO 2 nanocrystals with anatase and rutile mixed phases were prepared by incomplete oxidation of titanium nitride at different temperatures. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), core level X-ray photoelectron spectroscopy (CL XPS), valence band X-ray photoelectron spectroscopy (VB XPS), UV-vis diffuse reflectance spectra (UV-vis DRS), and visible light excited photoluminescence (PL). The photocatalytic activity was evaluated for photocatalytic degradation of toluene in gas phase under visible light irradiation. The visible light absorption and photoactivities of these nitrogen doped TiO 2 nanocrystals can be clearly attributed to the change of the additional electronic (N - ) states above the valence band of TiO 2 modified by N dopant as revealed by the VB XPS and visible light induced PL. A band gap structure model was established to explain the electron transfer process over nitrogen doped TiO 2 nanocrystals under visible light irradiation, which was consistent with the previous theoretical and experimental results. This model can also be applied to understand visible light induced photocatalysis over other nonmetal doped TiO 2

  10. Dysfunction of different cellular degradation pathways contributes to specific β-amyloid42-induced pathologies.

    Science.gov (United States)

    Ji, Xuan-Ru; Cheng, Kuan-Chung; Chen, Yu-Ru; Lin, Tzu-Yu; Cheung, Chun Hei Antonio; Wu, Chia-Lin; Chiang, Hsueh-Cheng

    2018-03-01

    The endosomal-lysosomal system (ELS), autophagy, and ubiquitin-proteasome system (UPS) are cellular degradation pathways that each play a critical role in the removal of misfolded proteins and the prevention of the accumulation of abnormal proteins. Recent studies on Alzheimer's disease (AD) pathogenesis have suggested that accumulation of aggregated β-amyloid (Aβ) peptides in the AD brain results from a dysfunction in these cellular clearance systems. However, the specific roles of these pathways in the removal of Aβ peptides and the pathogenesis underlying AD are unclear. Our in vitro and in vivo genetic approaches revealed that ELS mainly removed monomeric β-amyloid42 (Aβ42), while autophagy and UPS clear oligomeric Aβ42. Although overproduction of phosphatidylinositol 4-phosphate-5 increased Aβ42 clearance, it reduced the life span of Aβ42 transgenic flies. Our behavioral studies further demonstrated impaired autophagy and UPS-enhanced Aβ42-induced learning and memory deficits, but there was no effect on Aβ42-induced reduction in life span. Results from genetic fluorescence imaging showed that these pathways were damaged in the following order: UPS, autophagy, and finally ELS. The results of our study demonstrate that different degradation pathways play distinct roles in the removal of Aβ42 aggregates and in disease progression. These findings also suggest that pharmacologic treatments that are designed to stimulate cellular degradation pathways in patients with AD should be used with caution.-Ji, X.-R., Cheng, K.-C., Chen, Y.-R., Lin, T.-Y., Cheung, C. H. A., Wu, C.-L., Chiang, H.-C. Dysfunction of different cellular degradation pathways contributes to specific β-amyloid42-induced pathologies.

  11. The influence of different light quality and benzene on gene expression and benzene degradation of Chlorophytum comosum.

    Science.gov (United States)

    Setsungnern, Arnon; Treesubsuntorn, Chairat; Thiravetyan, Paitip

    2017-11-01

    Benzene, a carcinogenic compound, has been reported as a major indoor air pollutant. Chlorophytum comosum (C. comosum) was reported to be the highest efficient benzene removal plant among other screened plants. Our previous studies found that plants under light conditions could remove gaseous benzene higher than under dark conditions. Therefore, C. comosum exposure to airborne benzene was studied under different light quality at the same light intensity. C. comosum could remove 500 ppm gaseous benzene with the highest efficiency of 68.77% under Blue:Red = 1:1 LED treatments and the lowest one appeared 57.41% under white fluorescent treatment within 8 days. After benzene was uptaken by C. comosum, benzene was oxidized to be phenol in the plant cells by cytochrome P450 monooxygenase system. Then, phenol was catalyzed to be catechol that was confirmed by the up-regulation of phenol 2-monooxygenase (PMO) gene expression. After that, catechol was changed to cic, cis-muconic acid. Interestingly, cis,cis-muconic acid production was found in the plant tissues higher than phenol and catechol. The result confirmed that NADPH-cytochrome P450 reductase (CPR), cytochrome b5 (cyt b5), phenol 2-monooxygenase (PMO) and cytochrome P450 90B1 (CYP90B1) in plant cells were involved in benzene degradation or detoxification. In addition, phenol, catechol, and cis,cis-muconic acid production were found under the Blue-Red LED light conditions higher than under white fluorescent light conditions due to under LED light conditions gave higher NADPH contents. Hence, C. comosum under the Blue-Red LED light conditions had a high potential to remove benzene in a contaminated site. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  12. AgBr/diatomite for the efficient visible-light-driven photocatalytic degradation of Rhodamine B

    Science.gov (United States)

    Fang, Jing; Zhao, Huamei; Liu, Qinglei; Zhang, Wang; Gu, Jiajun; Su, Yishi; Abbas, Waseem; Su, Huilan; You, Zhengwei; Zhang, Di

    2018-03-01

    The treatment of organic pollution via photocatalysis has been investigated for a few decades. However, earth-abundant, cheap, stable, and efficient substrates are still to be developed. Here, we prepare an efficient visible-light-driven photocatalyst via the deposition of Ag nanoparticles (light intensity. For comparison, AgBr/SiO2 ( κ = 0.04 min-1) and commercial AgBr nanoparticles ( κ = 0.05 min-1) were measured as well. The experimental results reveal that diatomite acted more than a substrate benefiting the dispersion of AgBr nanoparticles, as well as a cooperator to help harvest visible light and adsorb dye molecules, leading to the efficient visible-light-driven photocatalytic performance of AgBr/diatomite. Considering the low cost (10 per ton) and large-scale availability of diatomite, our study provides the possibility to prepare other types of diatomite-based efficient photocatalytic composites with low-cost but excellent photocatalytic performance.

  13. A comparative study on the radiation induced degradation of chlorinated organics and water

    International Nuclear Information System (INIS)

    Bekboelet, M.; Balcioglu, A.I.; Getoff, N.

    1998-01-01

    Complete text of publication follows. Radiation induced degradation of chlorinated benzaldehydes has been studied by the application of UV-photolysis, UV-assisted catalytic oxidation and gamma radiolysis processes. The degradation was followed in terms of the substrate removal and formation of the decomposition products such as chloride and formaldehyde. Formation of the acidic compounds were also determined by the pH decrease during irradiation periods. The below given table summarizes the obtained results in terms of photochemical G (G PH )values. The main idea of this paper was to evaluate the applied processes in relation to the end products rather and to compare the efficiency of the methods. Besides, chloride and formaldehyde formation, the substrate degradation and formation of the stable end products, were followed by HPLC analyses. Hydroxylated parent compounds chlorophenols, benzaldehyde were also detected. Formation of muconic acid through ring opening as well as the formation of lower molecular weight organic acids by decomposition such as oxalic, citric, tartaric and formic acids were observed with respect the applied oxidation process. Depending on the formed stable end products and the related probable reaction mechanisms, isomeric positions were found to be selective toward oxidative degradation

  14. Light-induced bird strikes on vessels in Southwest Greenland

    DEFF Research Database (Denmark)

    Merkel, Flemming Ravn; Johansen, Kasper Lambert

    2011-01-01

    Light-induced bird strikes are known to occur when vessels navigate during darkness in icy waters using powerful searchlight. In Southwest Greenland, which is important internationally for wintering seabirds, we collected reports of incidents of bird strikes over 2–3 winters (2006–2009) from navy...... vessels, cargo vessels and trawlers (total n = 19). Forty-one incidents were reported: mainly close to land (birds were reported killed in a single incident. All occurred between 5 p.m. and 6 a.m. and significantly more birds were involved when...... visibility was poor (snow) rather than moderate or good. Among five seabird species reported, the common eider (Somateria mollissima) accounted for 95% of the bird casualties. Based on spatial analyses of data on vessel traffic intensity and common eider density we are able to predict areas with high risk...

  15. Functional analysis of chloroplast early light inducible proteins (ELIPs)

    Energy Technology Data Exchange (ETDEWEB)

    Wetzel, Carolyn M

    2005-02-22

    The objectives of this project were to characterize gene expression patterns of early light inducible protein (ELIP) genes in Arabidopsis thaliana and in Lycopersicon esculentum, to identify knock mutants of the 2 ELIP genes in Arabidopsis, and to characterize the effects of the knockouts. Expression in Arabidopsis was studied in response to thylakoid electron transport chain (PETC) capacity, where it was found that there is a signal for expression associated with reduction of the PETC. Expression in response to salt was also studied, with different responses of the two gene copies. Knockout lines for ELIP1 and ELIP2 have been identified and are being characterized. In tomato, it was found that the single-copy ELIP gene is highly expressed in ripening fruit during the chloroplast-to-chromoplast transition. Studies of expression in tomato ripening mutants are ongoing.

  16. Ultraviolet-light-induced processes in germanium-doped silica

    DEFF Research Database (Denmark)

    Kristensen, Martin

    2001-01-01

    A model is presented for the interaction of ultraviolet (UV) light with germanium-doped silica glass. It is assumed that germanium sites work as gates for transferring the excitation energy into the silica. In the material the excitation induces forbidden transitions to two different defect states...... which are responsible for the observed refractive index changes. Activation energies [1.85 +/-0.15 eV and 1.91 +/-0.15 eV] and rates [(2.7 +/-1.9) x 10(13) Hz and(7.2 +/-4.5) x 10(13) Hz] are determined for thermal elimination of these states. Good agreement is found with experimental results and new UV...

  17. Synthesis of surface oxygen-deficient BiPO{sub 4} nanocubes with enhanced visible light induced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Bingtao; Yin, Haoyong; Li, Tao; Gong, Jianying; Lv, Shumei; Nie, Qiulin, E-mail: yhy@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou (China)

    2017-05-15

    The visible light driven BiPO{sub 4} nanocubes with sufficient surface oxygen deficiency were fabricated by a hydrothermal process and subsequently ultrasonic assistant Fe reduction process. The products were characterized by XRD, DRS, XPS, SEM and TEM which showed that the BiPO{sub 4} had cuboid-like shape with a smooth surface and clear edges and the oxygen vacancies were successfully introduced on the surface of the BiPO{sub 4} nanocubes. The as prepared oxygen-deficient BiPO{sub 4} nanocubes showed greatly enhanced visible light induced photocatalytic activity in degradation of Rhodamine B. The enhanced photocatalytic performance and expanded visible light response of BiPO{sub 4} may be due to the introduction of surface oxygen vacancies which can generate the oxygen vacancies mid-gap states lower to the conduction band of BiPO{sub 4}. (author)

  18. WSB1 overcomes oncogene-induced senescence by targeting ATM for degradation

    Science.gov (United States)

    Kim, Jung Jin; Lee, Seung Baek; Yi, Sang-Yeop; Han, Sang-Ah; Kim, Sun-Hyun; Lee, Jong-Min; Tong, Seo-Yun; Yin, Ping; Gao, Bowen; Zhang, Jun; Lou, Zhenkun

    2017-01-01

    Oncogene-induced senescence (OIS) or apoptosis through the DNA-damage response is an important barrier of tumorigenesis. Overcoming this barrier leads to abnormal cell proliferation, genomic instability, and cellular transformation, and finally allows cancers to develop. However, it remains unclear how the OIS barrier is overcome. Here, we show that the E3 ubiquitin ligase WD repeat and SOCS box-containing protein 1 (WSB1) plays a role in overcoming OIS. WSB1 expression in primary cells helps the bypass of OIS, leading to abnormal proliferation and cellular transformation. Mechanistically, WSB1 promotes ATM ubiquitination, resulting in ATM degradation and the escape from OIS. Furthermore, we identify CDKs as the upstream kinase of WSB1. CDK-mediated phosphorylation activates WSB1 by promoting its monomerization. In human cancer tissue and in vitro models, WSB1-induced ATM degradation is an early event during tumorigenic progression. We suggest that WSB1 is one of the key players of early oncogenic events through ATM degradation and destruction of the tumorigenesis barrier. Our work establishes an important mechanism of cancer development and progression in premalignant lesions. PMID:27958289

  19. Light-induced electronic non-equilibrium in plasmonic particles.

    Science.gov (United States)

    Kornbluth, Mordechai; Nitzan, Abraham; Seideman, Tamar

    2013-05-07

    We consider the transient non-equilibrium electronic distribution that is created in a metal nanoparticle upon plasmon excitation. Following light absorption, the created plasmons decohere within a few femtoseconds, producing uncorrelated electron-hole pairs. The corresponding non-thermal electronic distribution evolves in response to the photo-exciting pulse and to subsequent relaxation processes. First, on the femtosecond timescale, the electronic subsystem relaxes to a Fermi-Dirac distribution characterized by an electronic temperature. Next, within picoseconds, thermalization with the underlying lattice phonons leads to a hot particle in internal equilibrium that subsequently equilibrates with the environment. Here we focus on the early stage of this multistep relaxation process, and on the properties of the ensuing non-equilibrium electronic distribution. We consider the form of this distribution as derived from the balance between the optical absorption and the subsequent relaxation processes, and discuss its implication for (a) heating of illuminated plasmonic particles, (b) the possibility to optically induce current in junctions, and (c) the prospect for experimental observation of such light-driven transport phenomena.

  20. Effects of day-time exposure to different light intensities on light-induced melatonin suppression at night.

    Science.gov (United States)

    Kozaki, Tomoaki; Kubokawa, Ayaka; Taketomi, Ryunosuke; Hatae, Keisuke

    2015-07-04

    Bright nocturnal light has been known to suppress melatonin secretion. However, bright light exposure during the day-time might reduce light-induced melatonin suppression (LIMS) at night. The effective proportion of day-time light to night-time light is unclear; however, only a few studies on accurately controlling both day- and night-time conditions have been conducted. This study aims to evaluate the effect of different day-time light intensities on LIMS. Twelve male subjects between the ages of 19 and 23 years (mean ± S.D., 20.8 ± 1.1) gave informed consent to participate in this study. They were exposed to various light conditions (day-time light conditions). They were then exposed to bright light (300 lx) again between 01:00 and 02:30 (night-time light exposure). They provided saliva samples before (00:55) and after night-time light exposure (02:30). A one-tailed paired t test yielded significant decrements of melatonin concentration after night-time light exposure under day-time dim, 100- and 300-lx light conditions. No significant differences exist in melatonin concentration between pre- and post-night-time light exposure under day-time 900- and 2700-lx light conditions. Present findings suggest the amount of light exposure needed to prevent LIMS caused by ordinary nocturnal light in individuals who have a general life rhythm (sleep/wake schedule). These findings may be useful in implementing artificial light environments for humans in, for example, hospitals and underground shopping malls.

  1. Biphasic TiO2 nanoparticles decorated graphene nanosheets for visible light driven photocatalytic degradation of organic dyes

    Science.gov (United States)

    Alamelu, K.; Raja, V.; Shiamala, L.; Jaffar Ali, B. M.

    2018-02-01

    We present characterization of biphasic TiO2 nanoparticles and its graphene nanocomposite synthesized by cost effective, hydrothermal method. The structural properties and morphology of the samples were characterized by series of spectroscopic and microscopic techniques. Introducing high surface area graphene could suppress the electron hole pair recombination rate in the nanocomposite. Further, the nanocomposite shows red-shift of the absorption edge and contract of the band gap from 2.98 eV to 2.85 eV. We have characterized its photocatalytic activity under natural sunlight and UV filtered sunlight irradiation. Data reveal graphene-TiO2 composite exhibit about 15 and 3.5 folds increase in degradability of Congo red and Methylene Blue dyes, respectively, comparison to pristine TiO2. This underscores the marginal effect of UV component of sunlight on the degradation ability of composite, implying its increased efficiency in harnessing visible region of solar spectrum. We have thus developed a visible light active graphene composite catalyst that can degrade both cationic and anionic dyes and making it potentially useful in environmental remediation and water splitting applications, under direct sunlight.

  2. Water and oxygen induced degradation of small molecule organic solar cells

    DEFF Research Database (Denmark)

    Hermenau, Martin; Riede, Moritz; Leo, Karl

    2011-01-01

    Small molecule organic solar cells were studied with respect to water and oxygen induced degradation by mapping the spatial distribution of reaction products in order to elucidate the degradation patterns and failure mechanisms. The active layers consist of a 30 nm bulk heterojunction formed......,4′-diamine p-doped with C60F36 (MeO-TPD:C60F36), which acted as hole transporting layer. Indium-tin-oxide (ITO) and aluminum served as hole and electron collecting electrode, respectively. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) in conjunction...... of aluminum oxide at the BPhen/Al interface, and diffusion of water into the ZnPc:C60 layer where ZnPc becomes oxidized. Finally, diffusion from the electrodes was found to have no or a negligible effect on the device lifetime....

  3. Studies on γ-irradiation-induced-degradation of chloramphenicol in aqueous solution

    International Nuclear Information System (INIS)

    Xie Fang; Ha Yiming; Wang Feng; Zhou Hongjie

    2008-01-01

    The irradiation-induced degradation of chloramphenicol by γ-rays in aqueous solution was studied and the radiolytical products were determined. The relationship among degradation rate, absorbed dose and initial concentration have been explored by comparing the position of maximum absorption peaks of chloramphenicol be- fore and after irradiation using high performance liquid chromatography. The identification of radiolytical products has been conducted using liquid chromatography tandem mass spectrometry. It has been found that the relationship among C/C 0 , absorbed dose and initial concentration can be fit with index curve. After irradiation, more than 30 radiolytical products with stable absorption below 278nm could be determined. 8 major radiolytical products with [M-H] - 353, 337, 335(A), 335(B), 319, 289, 127, 166, which are detected in several different conditions, have been picked up. Their possible structures are deducted. (authors)

  4. Strain induced irreversible critical current degradation in highly dense Bi-2212 round wire

    CERN Document Server

    Bjoerstad, R; Rikel, M.O.; Ballarino, A; Bottura, L; Jiang, J; Matras, M; Sugano, M; Hudspeth, J; Di Michiel, M

    2015-01-01

    The strain induced critical current degradation of overpressure processed straight Bi 2212/Ag wires has been studied at 77 K in self-field. For the first time superconducting properties, lattice distortions, composite wire stress and strain have been measured simultaneously in a high energy synchrotron beamline. A permanent Ic degradation of 5% occurs when the wire strain exceeds 0.60%. At a wire strain of about 0.65% a drastic n value and Ic reduction occur, and the composite stress and the Bi-2212 lattice parameter reach a plateau, indicating Bi-2212 filament fracturing. The XRD measurements show that Bi-2212 exhibits linear elastic behaviour up to the irreversible strain limit.

  5. Application of controlled radiation-induced degradation in polymers: less exploited aspect of radiation processing of polymers

    International Nuclear Information System (INIS)

    Haji Saeid, M.; Guven, O.

    2007-01-01

    Industrial use of ionizing radiation treatment has been most successful in applications related to polymeric materials. The polymer, plastics and rubber industries have benefited from the unique advantages of ionizing radiation since its inception as an industrial tool to modify their properties and manufacture novel materials with value addition to the end product. The established and emerging applications of electron beam processing of polymers are based on the well known ultimate effects of ionizing radiation on polymers namely, crosslinking, curing, grafting and chain scissioning. Radiation-induced crosslinking dominates most applications, whereas the chain scissioning effect is much less explored and currently limited to radiation-induced degradation of Teflon, cellulose and polypropylene. The controlling of radiation-induced degradation for achieving a target average molecular weight or distribution has been evaluated for some polysaccharides, biopolymers and waste inner tubes whereas mitigation of the degradative effects of radiation has been analyzed from the point of view of using certain stabilizers, copolymers and annealing at an appropriate temperature. Several new or highly specialized techniques such as positron annihilation lifetime spectroscopy. Rutherford backscattering, elastic recoil detection analysis and solid waste NMR spectroscopy and gas chromatography-mass spectroscopy have been applied to the study or radiation-induced degradation. New information has been collected on the morphological changes associated with radiation-induced degradation processes, including chain scission, oxidation and free volume alteration. The IAEA coordinated research project (CRP) on Controlling of Degradation Effects in Radiation Processing of Polymers dealt with the role and importance of using ionizing radiation in controlling properties of natural and synthetic polymers through its degradative effect. This paper provides a summary of most important results

  6. Hierarchical 3C-SiC nanowires as stable photocatalyst for organic dye degradation under visible light irradiation

    International Nuclear Information System (INIS)

    Zhang, Judong; Chen, Jianjun; Xin, Lipeng; Wang, Mingming

    2014-01-01

    Graphical abstract: The photocatalytic performance was enhanced by hierarchical nanostructural SiC nanowires due to the increased specific surface areas and efficient incident light scattering. The positive effect of SiO 2 layer growth on the surface of nanowires during the catalytic process on the high decolorization efficiency of SiC nanowires was attributed to SiO 2 surface oxygen vacancies. -- Highlights: • High decolorization rate of methylene blue using hierarchical 3C-SiC nanowires was obtained. • The effect of methylene blue with different concentration to catalytic result was investigated. • The photocatalytic reaction mechanism of degrading methylene blue was explained. • The SiO 2 layer generating on nanowire surface in the catalytic process was analyzed. -- Abstract: 3C-SiC nanowires with hierarchical structure were synthesized by sol–gel carbothermal reduction method. The photocatalytic property of SiC nanowires was investigated. 3C-SiC hierarchical nanowires exhibited an enhanced photocatalytic activity by accelerating the photocatalytic degradation of methylene blue solution under visible light irradiation. Methylene blue was degraded efficiently after 5 h irradiation over the photocatalyst. The photocatalytic activity was affected by the initial concentration of the methylene blue solution. Silicon dioxide layer was observed on the surface of nanowires after the catalytic process. The positive effect of SiO 2 surface oxygen vacancies and 3C-SiC hierarchical nanostructures on the high decolorization efficiency of SiC nanowires was discussed. The detailed photocatalytic redox processes were also explained

  7. Report of the workshop on 'light particle-induced reactions'

    International Nuclear Information System (INIS)

    1992-01-01

    The study meeting on light particle (mass number = 3 - 11)-induced reation was held for three days from December 5 to 7, 1991 at the Research Center for Nuclear Physics, Osaka University. This book records the report based on the lectures presented at the meeting. In the new facility of the RCNP, the experiment on the nuclear reaction using 400 MeV polarized protons and 200 MeV polarized deuterons is about to begin. When the acceleration of polarized He-3 beam which is being developed at present becomes feasible, by combining it with the high resolution spectrometer GRAND RAIDEN, it is expected that the unique, high accuracy research using the polarized He-3 having intermediate energy (540 MeV) becomes possible. At this time, by focusing attention to what new physics is developed by the nuclear reaction induced by the composite particles having the intermediate energy of mass number 3 - 11, this study meeting was planned and held. As the results, 29 lectures collected in this book were to cover wide fields, and active discussion was carried out. (K.I.)

  8. Palmitoylation regulates 17β-estradiol-induced estrogen receptor-α degradation and transcriptional activity.

    Science.gov (United States)

    La Rosa, Piergiorgio; Pesiri, Valeria; Leclercq, Guy; Marino, Maria; Acconcia, Filippo

    2012-05-01

    The estrogen receptor-α (ERα) is a transcription factor that regulates gene expression through the binding to its cognate hormone 17β-estradiol (E2). ERα transcriptional activity is regulated by E2-evoked 26S proteasome-mediated ERα degradation and ERα serine (S) residue 118 phosphorylation. Furthermore, ERα mediates fast cell responses to E2 through the activation of signaling cascades such as the MAPK/ERK and phosphoinositide-3-kinase/v-akt murine thymoma viral oncogene homolog 1 pathways. These E2 rapid effects require a population of the ERα located at the cell plasma membrane through palmitoylation, a dynamic enzymatic modification mediated by palmitoyl-acyl-transferases. However, whether membrane-initiated and transcriptional ERα activities integrate in a unique picture or represent parallel pathways still remains to be firmly clarified. Hence, we evaluated here the impact of ERα palmitoylation on E2-induced ERα degradation and S118 phosphorylation. The lack of palmitoylation renders ERα more susceptible to E2-dependent degradation, blocks ERα S118 phosphorylation and prevents E2-induced ERα estrogen-responsive element-containing promoter occupancy. Consequently, ERα transcriptional activity is prevented and the receptor addressed to the nuclear matrix subnuclear compartment. These data uncover a circuitry in which receptor palmitoylation links E2-dependent ERα degradation, S118 phosphorylation, and transcriptional activity in a unique molecular mechanism. We propose that rapid E2-dependent signaling could be considered as a prerequisite for ERα transcriptional activity and suggest an integrated model of ERα intracellular signaling where E2-dependent early extranuclear effects control late receptor-dependent nuclear actions.

  9. Assessment of Current Inservice Inspection and Leak Monitoring Practices for Detecting Materials Degradation in Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Michael T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Simonen, Fredric A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Muscara, Joseph [US Nuclear Regulatory Commission (NRC), Rockville, MD (United States); Doctor, Steven R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kupperman, David S. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-09-01

    An assessment was performed to determine the effectiveness of existing inservice inspection (ISI) and leak monitoring techniques, and recommend improvements, as necessary, to the programs as currently performed for light water reactor (LWR) components. Information from nuclear power plant (NPP) aging studies and from the U. S. Nuclear Regulatory Commission’s Generic Aging Lessons Learned (GALL) report (NUREG-1801) was used to identify components that have already experienced, or are expected to experience, degradation. This report provides a discussion of the key aspects and parameters that constitute an effective ISI program and a discussion of the basis and background against which the effectiveness of the ISI and leak monitoring programs for timely detection of degradation was evaluated. Tables based on the GALL components were used to systematically guide the process, and table columns were included that contained the ISI requirements and effectiveness assessment. The information in the tables was analyzed using histograms to reduce the data and help identify any trends. The analysis shows that the overall effectiveness of the ISI programs is very similar for both boiling water reactors (BWRs) and pressurized water reactors (PWRs). The evaluations conducted as part of this research showed that many ISI programs are not effective at detecting degradation before its extent reached 75% of the component wall thickness. This work should be considered as an assessment of NDE practices at this time; however, industry and regulatory activities are currently underway that will impact future effectiveness assessments. A number of actions have been identified to improve the current ISI programs so that degradation can be more reliably detected.

  10. Gadolinium oxide decorated multiwalled carbon nanotube/tridoped titania nanocomposites for improved dye degradation under simulated solar light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mamba, Gcina [Department of Applied Chemistry, University of Johannesburg, Faculty of Science, P.O. Box 17011, Doornfontein 2028 (South Africa); Nanotechnology and Water Sustainability Research Unit, College of Engineering, Science and Technology, University of South Africa Florida Science Campus, 1709 Florida (South Africa); Mbianda, Xavier Yangkou [Department of Applied Chemistry, University of Johannesburg, Faculty of Science, P.O. Box 17011, Doornfontein 2028 (South Africa); Mishra, Ajay Kumar, E-mail: mishrak@unisa.ac.za [Nanotechnology and Water Sustainability Research Unit, College of Engineering, Science and Technology, University of South Africa Florida Science Campus, 1709 Florida (South Africa)

    2016-03-15

    Graphical abstract: Illustration of the collaborative effect between MWCNT-Gd and Gd,N,S-TiO{sub 2} towards degradation of AB 74. - Highlights: • MWCNT-Gd/tridoped titania was successfully prepared via a sol-gel method. • XPS revealed the presence of Ti, C, O, S, N and Gd in MWCNT-Gd/Gd,N,S-TiO{sub 2}. • MWCNT-Gd/Gd,N,S-TiO{sub 2} displayed 100% degradation of acid blue 74 in 150 min. • Over 60% TOC removal by MWCNT-Gd/Gd,N,S-TiO{sub 2}. - Abstract: Neodymium/gadolinium/europium, nitrogen and sulphur tridoped titania (Nd/Gd/Eu, N,S-TiO{sub 2}) was hybridised with pre-synthesised gadolinium oxide decorated multiwalled carbon nanotubes (MWCNT-Gd) using a sol–gel method. Subsequent to drying and calcination, composite photocatalysts: MWCNT-Gd/Nd,N,S-TiO{sub 2}, MWCNT-Gd/Gd,N,S-TiO{sub 2} and MWCNT-Gd/Eu,N,S-TiO{sub 2}, were obtained and characterised using TEM, SEM-EDX, UV–vis, XPS, XRD and FT-IR. Acid blue 74 (AB74) was used as a model dye to investigate the photocatalytic degradation properties of the prepared materials under simulated solar light irradiation. Coupling the different tridoped titania with MWCNT-Gd enhanced their activity compared to MWCNT/TiO{sub 2}, MWCNT-Gd/TiO{sub 2} and MWCNT/Gd,N,S-TiO{sub 2}. MWCNT-Gd/Gd,N,S-TiO{sub 2} showed the highest activity towards AB74 degradation reaching 100% decolourisation after 150 min of irradiation. Total organic carbon analysis revealed that over 50% of the AB74 molecules were completely mineralised after 180 min of irradiation in the presence of MWCNT-Gd/Gd,N,S-TiO{sub 2}.

  11. Geldanamycin-induced degradation of Chk1 is mediated by proteasome

    International Nuclear Information System (INIS)

    Nomura, M.; Nomura, N.; Yamashita, J.

    2005-01-01

    Checkpoint kinase 1 (Chk1) is a cell cycle regulator and a heat shock protein 90 (Hsp90) client. It is essential for cell proliferation and survival. In this report, we analyzed the mechanisms of Chk1 regulation in U87MG glioblastoma cells using Geldanamycin (GA), which interferes with the function of Hsp90. GA reduced Chk1 protein level but not its mRNA level in glioblastoma cells. Co-treatment with GA and cycloheximide (CHX), a protein synthesis inhibitor, induced a decrease of half-life of the Chk1 protein to 3 h and resulted in Chk1 down-regulation. CHX alone induced only 32% reduction of Chk1 protein even after 24 h. These findings indicated that reduction of Chk1 by GA was due to destabilization and degradation of the protein. In addition, GA-induced down-regulation of Chk1 was reversed by MG132, a specific proteasome inhibitor. And it was revealed that Chk1 was ubiquitinated by GA. These results have indicated that degradation of Chk1 by GA was mediated by the ubiquitin-proteasome pathway in U87MG glioblastoma cells

  12. Effect of top electrode material on radiation-induced degradation of ferroelectric thin film structures

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, Steven J.; Bassiri-Gharb, Nazanin [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Deng, Carmen Z.; Callaway, Connor P. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Paul, McKinley K. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Woodward Academy, College Park, Georgia 30337 (United States); Fisher, Kenzie J. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Riverwood International Charter School, Atlanta, Georgia 30328 (United States); Guerrier, Jonathon E.; Jones, Jacob L. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Rudy, Ryan Q.; Polcawich, Ronald G. [Army Research Laboratory, Adelphi, Maryland 20783 (United States); Glaser, Evan R.; Cress, Cory D. [Naval Research Laboratory, Washington, DC 20375 (United States)

    2016-07-14

    The effects of gamma irradiation on the dielectric and piezoelectric responses of Pb[Zr{sub 0.52}Ti{sub 0.48}]O{sub 3} (PZT) thin film stacks were investigated for structures with conductive oxide (IrO{sub 2}) and metallic (Pt) top electrodes. The samples showed, generally, degradation of various key dielectric, ferroelectric, and electromechanical responses when exposed to 2.5 Mrad (Si) {sup 60}Co gamma radiation. However, the low-field, relative dielectric permittivity, ε{sub r}, remained largely unaffected by irradiation in samples with both types of electrodes. Samples with Pt top electrodes showed substantial degradation of the remanent polarization and overall piezoelectric response, as well as pinching of the polarization hysteresis curves and creation of multiple peaks in the permittivity-electric field curves post irradiation. The samples with oxide electrodes, however, were largely impervious to the same radiation dose, with less than 5% change in any of the functional characteristics. The results suggest a radiation-induced change in the defect population or defect energy in PZT with metallic top electrodes, which substantially affects motion of internal interfaces such as domain walls. Additionally, the differences observed for stacks with different electrode materials implicate the ferroelectric–electrode interface as either the predominant source of radiation-induced effects (Pt electrodes) or the site of healing for radiation-induced defects (IrO{sub 2} electrodes).

  13. Plasmon-resonance-enhanced visible-light photocatalytic activity of Ag quantum dots/TiO2 microspheres for methyl orange degradation

    Science.gov (United States)

    Yu, Xin; Shang, Liwei; Wang, Dongjun; An, Li; Li, Zhonghua; Liu, Jiawen; Shen, Jun

    2018-06-01

    We successfully prepared Ag quantum dots modified TiO2 microspheres by facile solvothermal and calcination method. The as-prepared Ag quantum dots/TiO2 microspheres were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The Ag quantum dots/TiO2 photocatalyst showed excellent visible light absorption and efficient photocatalytic activity for methyl orange degradation. And the sample with the molar ratio of 0.05 (Ag to Ti) showed the best visible light photocatalytic activity for methyl orange degradation, mainly because of the surface plasmon resonance (SPR) effects of Ag quantum dots to generate electron and hole pairs for enhanced visible light photocatalysis. Finally, possible visible light photocatalytic mechanism of Ag quantum dots/TiO2 microspheres for methyl orange degradation was proposed in detail.

  14. Heat-stress and light-stress induce different cellular pathologies in the symbiotic dinoflagellate during coral bleaching.

    Science.gov (United States)

    Downs, C A; McDougall, Kathleen E; Woodley, Cheryl M; Fauth, John E; Richmond, Robert H; Kushmaro, Ariel; Gibb, Stuart W; Loya, Yossi; Ostrander, Gary K; Kramarsky-Winter, Esti

    2013-01-01

    Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m(-2) s(-1) PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching.

  15. Heat-stress and light-stress induce different cellular pathologies in the symbiotic dinoflagellate during coral bleaching.

    Directory of Open Access Journals (Sweden)

    C A Downs

    Full Text Available Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex, usually by expulsion or xenophagy (symbiophagy of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m(-2 s(-1 PAR at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching.

  16. Photocatalyzed degradation of flumequine by doped TiO2 and simulated solar light

    International Nuclear Information System (INIS)

    Nieto, J.; Freer, J.; Contreras, D.; Candal, R.J.; Sileo, E.E.; Mansilla, H.D.

    2008-01-01

    Titanium dioxide was obtained in its pure form (TiO 2 ) and in the presence of urea (u-TiO 2 ) and thiourea (t-TiO 2 ) using the sol-gel technique. The obtained powders were characterized by BET surface area analysis, Infrared Spectroscopy, Diffuse Reflectance Spectroscopy and the Rietveld refinement of XRD measurements. All the prepared catalysts show high anatase content (>99%). The a and b-cell parameters of anatase increase in the order TiO 2 2 2 , while the c-parameter presents the opposite trend. Because of the interplay in cell dimensions, the cell grows thicker and shorter when prepared in the presence of urea and thiourea, respectively. The cell volume decreases in the order t-TiO 2 > u-TiO 2 > TiO 2 . The photocatalytic activities of the samples were determined on flumequine under solar-simulated irradiation. The most active catalysts were u-TiO 2 and t-TiO 2 , reaching values over 90% of flumequine degradation after 15 min irradiation, compared with values of 55% for the pure TiO 2 catalyst. Changing simultaneously the catalyst amount (t-TiO 2 ) and pH, multivariate analysis using the response surface methodology was used to determine the roughly optimal conditions for flumequine degradation. The optimized conditions found were pH below 7 and a catalyst amount of 1.6 g L -1

  17. Light Water Reactor Sustainability Program: Survey of Models for Concrete Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Benjamin W. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation; Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States). Energy and Environment Science and Technology

    2014-08-01

    Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear facilities for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have predictive tools to address concerns related to aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to review and document the main aging mechanisms of concern for concrete structures in nuclear power plants (NPPs) and the models used in simulations of concrete aging and structural response of degraded concrete structures. This is in preparation for future work to develop and apply models for aging processes and response of aged NPP concrete structures in the Grizzly code. To that end, this report also provides recommendations for developing more robust predictive models for aging effects of performance of concrete.

  18. Inositol Polyphosphate Multikinase Inhibits Angiogenesis via Inositol Pentakisphosphate-Induced HIF-1α Degradation.

    Science.gov (United States)

    Fu, Chenglai; Tyagi, Richa; Chin, Alfred C; Rojas, Tomas; Li, Ruo-Jing; Guha, Prasun; Bernstein, Isaac A; Rao, Feng; Xu, Risheng; Cha, Jiyoung Y; Xu, Jing; Snowman, Adele M; Semenza, Gregg L; Snyder, Solomon H

    2018-02-02

    Inositol polyphosphate multikinase (IPMK) and its major product inositol pentakisphosphate (IP5) regulate a variety of cellular functions, but their role in vascular biology remains unexplored. We have investigated the role of IPMK in regulating angiogenesis. Deletion of IPMK in fibroblasts induces angiogenesis in both in vitro and in vivo models. IPMK deletion elicits a substantial increase of VEGF (vascular endothelial growth factor), which mediates the regulation of angiogenesis by IPMK. The regulation of VEGF by IPMK requires its catalytic activity. IPMK is predominantly nuclear and regulates gene transcription. However, IPMK does not apparently serve as a transcription factor for VEGF. HIF (hypoxia-inducible factor)-1α is a major determinant of angiogenesis and induces VEGF transcription. IPMK deletion elicits a major enrichment of HIF-1α protein and thus VEGF. HIF-1α is constitutively ubiquitinated by pVHL (von Hippel-Lindau protein) followed by proteasomal degradation under normal conditions. However, HIF-1α is not recognized and ubiquitinated by pVHL in IPMK KO (knockout) cells. IP5 reinstates the interaction of HIF-1α and pVHL. HIF-1α prolyl hydroxylation, which is prerequisite for pVHL recognition, is interrupted in IPMK-deleted cells. IP5 promotes HIF-1α prolyl hydroxylation and thus pVHL-dependent degradation of HIF-1α. Deletion of IPMK in mouse brain increases HIF-1α/VEGF levels and vascularization. The increased VEGF in IPMK KO disrupts blood-brain barrier and enhances brain blood vessel permeability. IPMK, via its product IP5, negatively regulates angiogenesis by inhibiting VEGF expression. IP5 acts by enhancing HIF-1α hydroxylation and thus pVHL-dependent degradation of HIF-1α. © 2017 American Heart Association, Inc.

  19. Crystallization-mediated amorphous Cu{sub x}O (x = 1, 2)/crystalline CuI p–p type heterojunctions with visible light enhanced and ultraviolet light restrained photocatalytic dye degradation performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongli; Cai, Yun; Zhou, Jian; Fang, Jun, E-mail: fangjun@njtech.edu.cn; Yang, Yang, E-mail: yangy@njtech.edu.cn

    2017-04-30

    Highlights: • Cu{sub x}O(x = 1, 2)/CuI p–p type heterojunctions were facilely constructed via crystallization-mediated approaches. • Cu{sub x}O/CuI heterojunctions exhibit effective visible-light-driven photocatalytic activity for dye degradation. • The Cu{sub x}O/CuI interface can enhance the spatial separation of the photogenerated electron–hole pairs. • This work represents a critical step for mass production of functional semiconductor heterojunctions in a mild manner. - Abstract: We report simple and cost-effective fabrication of amorphous Cu{sub x}O (x = 1, 2)/crystalline CuI p–p type heterojunctions based on crystallization-mediated approaches including antisolvent crystallization and crystal reconstruction. Starting from CuI acetonitrile solution, large crystals in commercial CuI can be easily converted to aggregates consisting of small particles by the crystallization processes while the spontaneous oxidation of CuI by atmospheric/dissolved oxygen can induce the formation of trace Cu{sub x}O on CuI surface. As a proof of concept, the as-fabricated Cu{sub x}O/CuI heterojunctions exhibit effective photocatalytic activity towards the degradation of methyl blue and other organic pollutants under visible light irradiation, although the wide band-gap semiconductor CuI is insensible to visible light. Unexpectedly, the Cu{sub x}O/CuI heterojunctions exhibit restrained photocatalytic activity when ultraviolet light is applied in addition to the visible. It is suggested that the Cu{sub x}O/CuI interface can enhance the spatial separation of the electron–hole pairs with the excitation of Cu{sub x}O under visible light and prolong the lifetime of photogenerated charges with high redox ability. The present work represents a critically important step in advancing the crystallization technique for potential mass production of semiconductor heterojunctions in a mild manner.

  20. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

    Energy Technology Data Exchange (ETDEWEB)

    Hao Xiaolong [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Zhou Ming Hua [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Lei Lecheng [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China)]. E-mail: lclei@zju.edu.cn

    2007-03-22

    TiO{sub 2} photocatalyst (P-25) (50 mg L{sup -1}) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO{sub 2} were obviously increased. Pulsed high-voltage discharge process with TiO{sub 2} had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10 x 10{sup -6} to 1.50 x 10{sup -6} M s{sup -1}, the ozone formation rate from 1.99 x 10{sup -8} to 2.35 x 10{sup -8} M s{sup -1}, respectively. In addition, this process had no influence on the photocatalytic properties of TiO{sub 2}. The introduction of TiO{sub 2} photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.

  1. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water.

    Science.gov (United States)

    Hao, Xiao Long; Zhou, Ming Hua; Lei, Le Cheng

    2007-03-22

    TiO(2) photocatalyst (P-25) (50mgL(-1)) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO(2) were obviously increased. Pulsed high-voltage discharge process with TiO(2) had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10x10(-6) to 1.50x10(-6)Ms(-1), the ozone formation rate from 1.99x10(-8) to 2.35x10(-8)Ms(-1), respectively. In addition, this process had no influence on the photocatalytic properties of TiO(2). The introduction of TiO(2) photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.

  2. Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

    International Nuclear Information System (INIS)

    Hao Xiaolong; Zhou Ming Hua; Lei Lecheng

    2007-01-01

    TiO 2 photocatalyst (P-25) (50 mg L -1 ) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO 2 were obviously increased. Pulsed high-voltage discharge process with TiO 2 had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10 x 10 -6 to 1.50 x 10 -6 M s -1 , the ozone formation rate from 1.99 x 10 -8 to 2.35 x 10 -8 M s -1 , respectively. In addition, this process had no influence on the photocatalytic properties of TiO 2 . The introduction of TiO 2 photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants

  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

    Science.gov (United States)

    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-degradation

  4. Molecular mechanism of 17-allylamino-17-demethoxygeldanamycin (17-AAG)-induced AXL receptor tyrosine kinase degradation.

    Science.gov (United States)

    Krishnamoorthy, Gnana Prakasam; Guida, Teresa; Alfano, Luigi; Avilla, Elvira; Santoro, Massimo; Carlomagno, Francesca; Melillo, Rosa Marina

    2013-06-14

    The receptor tyrosine kinase AXL is overexpressed in many cancer types including thyroid carcinomas and has well established roles in tumor formation and progression. Proper folding, maturation, and activity of several oncogenic receptor tyrosine kinases require HSP90 chaperoning. HSP90 inhibition by the antibiotic geldanamycin or its derivative 17-allylamino-17-demethoxygeldanamycin (17-AAG) causes destabilization of its client proteins. Here we show that AXL is a novel client protein of HSP90. 17-AAG induced a time- and dose-dependent down-regulation of endogenous or ectopically expressed AXL protein, thereby inhibiting AXL-mediated signaling and biological activity. 17-AAG-induced AXL down-regulation specifically affected fully glycosylated mature receptor present on cell membrane. By using biotin and [(35)S]methionine labeling, we showed that 17-AAG caused depletion of membrane-localized AXL by mediating its degradation in the intracellular compartment, thus restricting its exposure on the cell surface. 17-AAG induced AXL polyubiquitination and subsequent proteasomal degradation; under basal conditions, AXL co-immunoprecipitated with HSP90. Upon 17-AAG treatment, AXL associated with the co-chaperone HSP70 and the ubiquitin E3 ligase carboxyl terminus of HSC70-interacting protein (CHIP). Overexpression of CHIP, but not of the inactive mutant CHIP K30A, induced accumulation of AXL polyubiquitinated species upon 17-AAG treatment. The sensitivity of AXL to 17-AAG required its intracellular domain because an AXL intracellular domain-deleted mutant was insensitive to the compound. Active AXL and kinase-dead AXL were similarly sensitive to 17-AAG, implying that 17-AAG sensitivity does not require receptor phosphorylation. Overall our data elucidate the molecular basis of AXL down-regulation by HSP90 inhibitors and suggest that HSP90 inhibition in anticancer therapy can exert its effect through inhibition of multiple kinases including AXL.

  5. Molecular Mechanism of 17-Allylamino-17-demethoxygeldanamycin (17-AAG)-induced AXL Receptor Tyrosine Kinase Degradation*

    Science.gov (United States)

    Krishnamoorthy, Gnana Prakasam; Guida, Teresa; Alfano, Luigi; Avilla, Elvira; Santoro, Massimo; Carlomagno, Francesca; Melillo, Rosa Marina

    2013-01-01

    The receptor tyrosine kinase AXL is overexpressed in many cancer types including thyroid carcinomas and has well established roles in tumor formation and progression. Proper folding, maturation, and activity of several oncogenic receptor tyrosine kinases require HSP90 chaperoning. HSP90 inhibition by the antibiotic geldanamycin or its derivative 17-allylamino-17-demethoxygeldanamycin (17-AAG) causes destabilization of its client proteins. Here we show that AXL is a novel client protein of HSP90. 17-AAG induced a time- and dose-dependent down-regulation of endogenous or ectopically expressed AXL protein, thereby inhibiting AXL-mediated signaling and biological activity. 17-AAG-induced AXL down-regulation specifically affected fully glycosylated mature receptor present on cell membrane. By using biotin and [35S]methionine labeling, we showed that 17-AAG caused depletion of membrane-localized AXL by mediating its degradation in the intracellular compartment, thus restricting its exposure on the cell surface. 17-AAG induced AXL polyubiquitination and subsequent proteasomal degradation; under basal conditions, AXL co-immunoprecipitated with HSP90. Upon 17-AAG treatment, AXL associated with the co-chaperone HSP70 and the ubiquitin E3 ligase carboxyl terminus of HSC70-interacting protein (CHIP). Overexpression of CHIP, but not of the inactive mutant CHIP K30A, induced accumulation of AXL polyubiquitinated species upon 17-AAG treatment. The sensitivity of AXL to 17-AAG required its intracellular domain because an AXL intracellular domain-deleted mutant was insensitive to the compound. Active AXL and kinase-dead AXL were similarly sensitive to 17-AAG, implying that 17-AAG sensitivity does not require receptor phosphorylation. Overall our data elucidate the molecular basis of AXL down-regulation by HSP90 inhibitors and suggest that HSP90 inhibition in anticancer therapy can exert its effect through inhibition of multiple kinases including AXL. PMID:23629654

  6. Tunable atom-light beam splitter using electromagnetically induced transparency

    Science.gov (United States)

    Zhu, Xinyu; Wen, Rong; Chen, J. F.

    2018-06-01

    With electromagnetically induced transmission (EIT), an optical field can be converted into collective atomic excitation and stored in the atomic medium through switching off the strong-coupling field adiabatically. By varying the power of the coupling pulse, we can control the ratio between the transmitted optical field and the stored atomic mode. We use a cloud of cold 85Rb atoms prepared in magneto-optical trap as the experimental platform. Based on a model of EIT dark-state polariton, we consider the real case where the atomic medium has a finite length. The theoretical calculation gives numerical results that agree well with the experimental data. The results show that the ratio can be changed approximately from 0 to 100%, when the maximum power of the coupling pulse (the pulse length is 100 ns) varies from 0 to 20 mW, in the cold atomic ensemble with an optical depth of 40. This process can be used to achieve an atom-light hybrid beam splitter with tunable splitting ratio and thus find potential application in interferometric measurement and quantum information processing.

  7. The LILIA (laser induced light ions acceleration) experiment at LNF

    International Nuclear Information System (INIS)

    Agosteo, S.; Anania, M.P.; Caresana, M.; Cirrone, G.A.P.; De Martinis, C.; Delle Side, D.; Fazzi, A.; Gatti, G.; Giove, D.; Giulietti, D.; Gizzi, L.A.; Labate, L.; Londrillo, P.; Maggiore, M.; Nassisi, V.; Sinigardi, S.; Tramontana, A.; Schillaci, F.; Scuderi, V.; Turchetti, G.

    2014-01-01

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50–75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given

  8. The LILIA (laser induced light ions acceleration) experiment at LNF

    Energy Technology Data Exchange (ETDEWEB)

    Agosteo, S. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Anania, M.P. [INFN LNF Frascati, Frascati (Italy); Caresana, M. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Cirrone, G.A.P. [INFN LNS Catania, Catania (Italy); De Martinis, C. [Physics Department, University of Milan and INFN, Milan (Italy); Delle Side, D. [LEAS, University of Salento and INFN, Lecce (Italy); Fazzi, A. [Energy Department, Polytechnic of Milan and INFN, Milan (Italy); Gatti, G. [INFN LNF Frascati, Frascati (Italy); Giove, D. [Physics Department, University of Milan and INFN, Milan (Italy); Giulietti, D. [Physics Department, University of Pisa and INFN, Pisa (Italy); Gizzi, L.A.; Labate, L. [INO-CNR and INFN, Pisa (Italy); Londrillo, P. [Physics Department, University of Bologna and INFN, Bologna (Italy); Maggiore, M. [INFN LNL, Legnaro (Italy); Nassisi, V., E-mail: vincenzo.nassisi@le.infn.it [LEAS, University of Salento and INFN, Lecce (Italy); Sinigardi, S. [Physics Department, University of Bologna and INFN, Bologna (Italy); Tramontana, A.; Schillaci, F. [INFN LNS Catania, Catania (Italy); Scuderi, V. [INFN LNS Catania, Catania (Italy); Institute of Physics of the ASCR, Prague (Czech Republic); Turchetti, G. [Physics Department, University of Bologna and INFN, Bologna (Italy); and others

    2014-07-15

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50–75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given.

  9. Gold nanoparticles enhance the X-ray-induced degradation of human centrin 2 protein

    Energy Technology Data Exchange (ETDEWEB)

    Brun, Emilie [Laboratoire de Chimie Physique, CNRS UMR 8000, Universite Paris-Sud 11, Bat. 350, 91405 Orsay Cedex (France); Duchambon, Patricia; Blouquit, Yves [INSERM U759, Imagerie Integrative, Campus Universitaire d' Orsay, Bat. 112, Institut Curie, Centre de Recherche, Laboratoire R. Latarjet, Campus Universitaire d' Orsay, 91405 Orsay Cedex (France); Keller, Gerard [UMR CNRS 8612, Physico-Chimie-Pharmacotechnie-Biopharmacie, Universite Paris 11, Faculte de Pharmacie, 5 rue Jean-Baptiste Clement, 92296 Chatenay-Malabry (France); Sanche, Leon [Groupe en Sciences des Radiations, Departement de Medecine Nucleaire et Radiobiologie, Faculte de Medecine, Universite de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4 (Canada); Sicard-Roselli, Cecile [Laboratoire de Chimie Physique, CNRS UMR 8000, Universite Paris-Sud 11, Bat. 350, 91405 Orsay Cedex (France)], E-mail: cecile.sicard@u-psud.fr

    2009-03-15

    In the war against cancer, radiotherapy is a prominent tool but counterbalanced by the fact that it also induces damages in healthy tissues. Nanotechnologies could open a new possibility to decrease these side effects. In particular, gold nanoparticles (GNPs) could be used as radio-sensitizers. As the role of proteins in the processes leading to cell death cannot be neglected, their radio-sensitization by GNPs is of great interest. This is particularly true in the case of the human centrin 2 protein, which has been proposed to be involved in DNA repair processes. To investigate this effect, we quantified for the first time the degradation of this protein in a gold colloidal solution when submitted to X-rays. We showed that the X-ray-induced degradation of the human centrin 2 protein is enhanced 1.5-fold in the presence of GNPs, even though no covalent bond exists between protein and GNPs. Among the conditions tested, the maximum enhancement was found with the higher GNP:protein ratio of 2x10{sup -4} and with the higher X-ray energy of 49 keV.

  10. Gold nanoparticles enhance the X-ray-induced degradation of human centrin 2 protein

    International Nuclear Information System (INIS)

    Brun, Emilie; Duchambon, Patricia; Blouquit, Yves; Keller, Gerard; Sanche, Leon; Sicard-Roselli, Cecile

    2009-01-01

    In the war against cancer, radiotherapy is a prominent tool but counterbalanced by the fact that it also induces damages in healthy tissues. Nanotechnologies could open a new possibility to decrease these side effects. In particular, gold nanoparticles (GNPs) could be used as radio-sensitizers. As the role of proteins in the processes leading to cell death cannot be neglected, their radio-sensitization by GNPs is of great interest. This is particularly true in the case of the human centrin 2 protein, which has been proposed to be involved in DNA repair processes. To investigate this effect, we quantified for the first time the degradation of this protein in a gold colloidal solution when submitted to X-rays. We showed that the X-ray-induced degradation of the human centrin 2 protein is enhanced 1.5-fold in the presence of GNPs, even though no covalent bond exists between protein and GNPs. Among the conditions tested, the maximum enhancement was found with the higher GNP:protein ratio of 2x10 -4 and with the higher X-ray energy of 49 keV

  11. Synthesize of Graphene-Tin Oxide Nanocomposite and Its Photocatalytic Properties for the Degradation of Organic Pollutants Under Visible Light.

    Science.gov (United States)

    Shanmugam, M; Jayavel, R

    2015-09-01

    Graphene-tinoxide nanocomposite has been synthesised by coating SnO2 nanoparticles on graphene sheets by the redox reaction between graphene oxide (GO) and tin chloride. Graphene oxide was reduced to graphene and Sn2+ was oxidized to SnO2 during the redox reaction, resulting in the uniform distribution of SnO2 nanoparticles on graphene sheets. The synthesised material was characterized by XRD, SEM, AFM, FT-IR, UV-vis, TGA and Raman spectroscopic studies. SEM and AFM studies reveal the formation of wrinkled paper like structure of graphene sheets with uniform coating of SnO2 nanoparticles on either side. The strong photocatalytic degradation of Methylene orange (MO) dye was analysed using G-SnO2 nanocomposite under the visible light irradiation.

  12. Point and line defects which are common to both degraded light emitting diodes and plastically deformed GaAs

    International Nuclear Information System (INIS)

    Liliental, Z.

    1983-01-01

    Similar dipoles with Burger's vector b = a/2 [101] (also referred to as dark line defects) were found in the active layer of degraded light emitting diodes (LED's) and in plastically deformed GaAs. The dependence of characteristic x-ray production of electron channeling conditions has been used in an electron microscope to study point defects in the neighbourhood of these dipoles. Our results are consistent with the occurence of I/sub As/, I/sub As/ +V/sub Ga/, V/sub Ga/ and IAs in descending order of likelihood. Of these, I/sub As/ +V/sub Ga/ can explain the dislocation climb without any extra point defects involved in such process

  13. Photocatalytic Degradation of Toluene, Butyl Acetate and Limonene under UV and Visible Light with Titanium Dioxide-Graphene Oxide as Photocatalyst

    Directory of Open Access Journals (Sweden)

    Birte Mull

    2017-01-01

    Full Text Available Photocatalysis is a promising technique to reduce volatile organic compounds indoors. Titanium dioxide (TiO2 is a frequently-used UV active photocatalyst. Because of the lack of UV light indoors, TiO2 has to be modified to get its working range shifted into the visible light spectrum. In this study, the photocatalytic degradation of toluene, butyl acetate and limonene was investigated under UV LED light and blue LED light in emission test chambers with catalysts either made of pure TiO2 or TiO2 modified with graphene oxide (GO. TiO2 coated with different GO amounts (0.75%–14% were investigated to find an optimum ratio for the photocatalytic degradation of VOC in real indoor air concentrations. Most experiments were performed at a relative humidity of 0% in 20 L emission test chambers. Experiments at 40% relative humidity were done in a 1 m³ emission test chamber to determine potential byproducts. Degradation under UV LED light could be achieved for all three compounds with almost all tested catalyst samples up to more than 95%. Limonene had the highest degradation of the three selected volatile organic compounds under blue LED light with all investigated catalyst samples.

  14. Nonlinear degradation of a visible-light communication link: A Volterra-series approach

    Science.gov (United States)

    Kamalakis, Thomas; Dede, Georgia

    2018-06-01

    Visible light communications can be used to provide illumination and data communication at the same time. In this paper, a reverse-engineering approach is presented for assessing the impact of nonlinear signal distortion in visible light communication links. The approach is based on the Volterra series expansion and has the advantage of accurately accounting for memory effects in contrast to the static nonlinear models that are popular in the literature. Volterra kernels describe the end-to-end system response and can be inferred from measurements. Consequently, this approach does not rely on any particular physical models and assumptions regarding the individual link components. We provide the necessary framework for estimating the nonlinear distortion on the symbol estimates of a discrete multitone modulated link. Various design aspects such as waveform clipping and predistortion are also incorporated in the analysis. Using this framework, the nonlinear signal-to-interference is calculated for the system at hand. It is shown that at high signal amplitudes, the nonlinear signal-to-interference can be less than 25 dB.

  15. Degradation of (InAlGa)N-based UV-B light emitting diodes stressed by current and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Glaab, Johannes, E-mail: johannes.glaab@fbh-berlin.de; Ploch, Christian; Kelz, Rico; Stölmacker, Christoph; Lapeyrade, Mickael; Ploch, Neysha Lobo; Rass, Jens; Kolbe, Tim; Einfeldt, Sven; Weyers, Markus [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Mehnke, Frank; Kuhn, Christian; Wernicke, Tim [Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin (Germany); Kneissl, Michael [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin (Germany)

    2015-09-07

    The degradation of the electrical and optical properties of (InAlGa)N-based multiple quantum well light emitting diodes (LEDs) emitting near 308 nm under different stress conditions has been studied. LEDs with different emission areas were operated at room temperature and at constant current densities of 75 A/cm{sup 2}, 150 A/cm{sup 2}, and 225 A/cm{sup 2}. In addition, the heat sink temperature was varied between 15 °C and 80 °C. Two main modes for the reduction of the optical power were found, which dominate at different times of operation: (1) Within the first 100 h, a fast drop of the optical power is observed scaling exponentially with the temperature and having an activation energy of about 0.13 eV. The drop in optical power is accompanied by changes of the current-voltage (I-V) characteristic. (2) For operation times beyond 100 h, the optical power decreases slowly which can be reasonably described by a square root time dependence. Here, the degradation rate depends on the current density, rather than the current. Again, the rate of optical power reduction of the second mode depends exponentially on the temperature with an activation energy of about 0.21 eV. The drop in the optical power is accompanied by an increased reverse-bias leakage current.

  16. Enhancement of tributyltin degradation under natural light by N-doped TiO{sub 2} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Bangkedphol, S., E-mail: sornnarin.bangkedphol@strath.ac.uk [David Livingstone Centre for Sustainability, Department of Civil Engineering, University of Strathclyde, Glasgow, Scotland G1 1XN (United Kingdom); Keenan, H.E. [David Livingstone Centre for Sustainability, Department of Civil Engineering, University of Strathclyde, Glasgow, Scotland G1 1XN (United Kingdom); Davidson, C.M. [WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, Scotland G1 1XL (United Kingdom); Sakultantimetha, A. [David Livingstone Centre for Sustainability, Department of Civil Engineering, University of Strathclyde, Glasgow, Scotland G1 1XN (United Kingdom); Sirisaksoontorn, W.; Songsasen, A. [Department of Chemistry and Centre for Innovation in chemistry, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand)

    2010-12-15

    Photo-degradation of tributyltin (TBT) has been enhanced by TiO{sub 2} nanoparticles doped with nitrogen (N-doped TiO{sub 2}). The N-doped catalyst was prepared by a sol-gel reaction of titanium (IV) tetraisopropoxide with 25% ammonia solution and calcined at various temperatures from 300 to 600 deg. C. X-ray diffraction results showed that N-doped TiO{sub 2} remained amorphous at 300 deg. C. At 400 deg. C the anatase phase occurred then transformed to the rutile phase at 600 deg. C. The crystallite size calculated from Scherrer's equation was in the range of 16-51 nm which depended on the calcination temperature. N-doped TiO{sub 2} calcined at 400 deg. C which contained 0.054% nitrogen, demonstrated the highest photocatalytic degradation of TBT at 28% in 3 h under natural light when compared with undoped TiO{sub 2} and commercial photocatalyst, P25-TiO{sub 2} which gave 14.8 and 18% conversion, respectively.

  17. Sm2FeTaO7 Photocatalyst for Degradation of Indigo Carmine Dye under Solar Light Irradiation

    Directory of Open Access Journals (Sweden)

    Leticia M. Torres-Martínez

    2012-01-01

    Full Text Available This paper is focused to study Sm2FeTaO7 pyrochlore-type compound as solar photocatalyst for the degradation of indigo carmine dye in aqueous solution. Sm2FeTaO7 was synthesized by using conventional solid state reaction and sol-gel method. X-ray diffraction results indicated that Sm2FeTaO7 exhibit a monoclinic crystal structure. By scanning electron microscopy analysis, it was observed that sol-gel material presents particle size of around 150 nm. The specific surface area and energy bandgap values were 12 m2 g−1 and 2.0 eV, respectively. The photocatalytic results showed that indigo carmine molecule can be degraded under solar light irradiation using the synthesized materials, sol-gel photocatalyst was 8 times more active than solid state. On the other hand, when Sm2FeTaO7 was impregnated with CuO as cocatalyst the photocatalytic activity was increased because CuO acts as electron trap decreasing electron-hole pair recombination rates.

  18. Degradation of (InAlGa)N-based UV-B light emitting diodes stressed by current and temperature

    International Nuclear Information System (INIS)

    Glaab, Johannes; Ploch, Christian; Kelz, Rico; Stölmacker, Christoph; Lapeyrade, Mickael; Ploch, Neysha Lobo; Rass, Jens; Kolbe, Tim; Einfeldt, Sven; Weyers, Markus; Mehnke, Frank; Kuhn, Christian; Wernicke, Tim; Kneissl, Michael

    2015-01-01

    The degradation of the electrical and optical properties of (InAlGa)N-based multiple quantum well light emitting diodes (LEDs) emitting near 308 nm under different stress conditions has been studied. LEDs with different emission areas were operated at room temperature and at constant current densities of 75 A/cm 2 , 150 A/cm 2 , and 225 A/cm 2 . In addition, the heat sink temperature was varied between 15 °C and 80 °C. Two main modes for the reduction of the optical power were found, which dominate at different times of operation: (1) Within the first 100 h, a fast drop of the optical power is observed scaling exponentially with the temperature and having an activation energy of about 0.13 eV. The drop in optical power is accompanied by changes of the current-voltage (I-V) characteristic. (2) For operation times beyond 100 h, the optical power decreases slowly which can be reasonably described by a square root time dependence. Here, the degradation rate depends on the current density, rather than the current. Again, the rate of optical power reduction of the second mode depends exponentially on the temperature with an activation energy of about 0.21 eV. The drop in the optical power is accompanied by an increased reverse-bias leakage current

  19. Solvothermal synthesis of graphene-Sb2S3 composite and the degradation activity under visible light

    International Nuclear Information System (INIS)

    Tao, Wenguang; Chang, Jiuli; Wu, Dapeng; Gao, Zhiyong; Duan, Xiaoli; Xu, Fang; Jiang, Kai

    2013-01-01

    Graphical abstract: Display Omitted Highlights: ► Graphene-Sb 2 S 3 composites were synthesized through a facile solvothermal method. ► Hydroxyl radicals are the main species responsible for the photodegradation activity. ► Graphene-Sb 2 S 3 demonstrated dramatically improved visible light degradation activity. -- Abstract: Novel graphene-Sb 2 S 3 (G-Sb 2 S 3 ) composites were synthesized via a facile solvothermal method with graphene oxide (GO), SbCl 3 and thiourea as the reactants. GO played an important role in controlling the size and the distribution of the formed Sb 2 S 3 nanoparticles on the graphene sheets with different density. Due to the negative surface charge, smaller Sb 2 S 3 particles size and efficient electrons transfer from Sb 2 S 3 to graphene, the composites demonstrated improved photodegradation activity on rhodamine B (RhB). Among these composites, the product G-Sb 2 S 3 0.1, which was synthesized with the GO concentration of 0.1 mg/mL, exhibited the highest photodegradation activity owing to the considerable density of Sb 2 S 3 nanoparticles onto graphene sheet free of aggregation. Hydroxyl radicals (·OH) derived from conduction band (CB) electrons of Sb 2 S 3 is suggested to be responsible for the photodegradation of RhB. The high visible light degradation activity and the satisfactory cycling stability made the as-prepared G-Sb 2 S 3 0.1 an applicable photocatalyst.

  20. Catalytic degradation of Acid Orange 7 by manganese oxide octahedral molecular sieves with peroxymonosulfate under visible light irradiation

    International Nuclear Information System (INIS)

    Duan, Lian; Sun, Binzhe; Wei, Mingyu; Luo, Shilu; Pan, Fei; Xu, Aihua; Li, Xiaoxia

    2015-01-01

    Highlights: • OMS-2/PMS/Vis system could efficiently catalyze the degradation of organic dyes. • The system showed much higher activity than that of OMS-2/PMS and OMS-2/Vis. • The OMS-2 catalyst exhibited stable performance for multiple runs. • Sulfate radicals were suggested to be the major reactive species in the system. • The radicals production might involve the redox cycle of Mn(IV)/Mn(III) and Mn(III)/Mn(II). - Abstract: In this paper, the photodegradation of Acid Orange 7 (AO7) in aqueous solutions with peroxymonosulfate (PMS) was studied with manganese oxide octahedral molecular sieves (OMS-2) as the catalyst. The activities of different systems including OMS-2 under visible light irradiation (OMS-2/Vis), OMS-2/PMS and OMS-2/PMS/Vis were evaluated. It was found that the efficiency of OMS-2/PMS was much higher than that of OMS-2/Vis and could be further enhanced by visible light irradiation. The catalyst also exhibited stable performance for multiple runs. Results from ESR and XPS analyses suggested that the highly catalytic activity of the OMS-2/PMS/Vis system possible involved the activation of PMS to sulfate radicals meditated by the redox pair of Mn(IV)/Mn(III) and Mn(III)/Mn(II), while in the OMS-2/PMS system, only the redox reaction between Mn(IV)/Mn(III) occurred. Several operational parameters, such as dye concentration, catalyst load, PMS concentration and solution pH, affected the degradation of AO7

  1. Light Water Reactor Sustainability Program: survey of models for concrete degradation

    International Nuclear Information System (INIS)

    2014-01-01

    Concrete has been used in the construction of nuclear facilities because of two primary properties: its structural strength and its ability to shield radiation. Concrete structures have been known to last for hundreds of years, but they are also known to deteriorate in very short periods of time under adverse conditions. The use of concrete in nuclear facilities for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. The goal of this report is to review and document the main aging mechanisms of concern for concrete structures in nuclear power plants (NPPs) and the models used in simulations of concrete aging and structural response of degraded concrete structures. This is in preparation for future work to develop and apply models for aging processes and response of aged NPP concrete structures in the Grizzly code. To that end, this report also provides recommendations for developing more robust predictive models for aging effects of performance of concrete.

  2. Analysis of chemical degradation mechanism of phosphorescent organic light emitting devices by laser-desorption/ionization time-of-flight mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rabelo de Moraes, Ines; Scholz, Sebastian; Luessem, Bjoern; Leo, Karl [Institut fuer Angewandte Photophysik, Technische Universitaet Dresden (Germany)

    2010-07-01

    Phosphorescent organic light emitting diodes (OLEDs) have attracted much interest for their potential application in full color flat-panel displays and as an alternative lighting source. However, low efficiency, and the short operation lifetime, in particular in the case of blue emitting devices, are the major limitations for the current OLEDs commercialization. In order to overcome these limitations, a deep knowledge about the aging and the degradation mechanism is required. Our work focuses on the chemical degradation mechanism of different iridium based emitter materials like FIrpic (light blue) and Ir(ppy)3 (green), commonly used in OLEDs. For this purpose, the devices were aged by electrical driving until the luminance reached 6% of the initial luminance. The laser-desorption/ionization time-of-flight mass spectrometry was used to determine specific degradation pathways.

  3. Experimental Warming Aggravates Degradation-Induced Topsoil Drought in Alpine Meadows of The Qinghai-Tibetan Plateau

    Science.gov (United States)

    Xue, X.

    2017-12-01

    Climatic warming is presumed to cause topsoil drought by increasing evapotranspiration and water infiltration, and by progressively inducing land degradation in alpine meadows of the Qinghai-Tibetan Plateau. However, how soil moisture and temperature patterns of degraded alpine meadows respond to climate warming remains unclear. A six-year continuous warming experiment was carried out in both degraded and undegraded alpine meadows in the source region of the Yangtze River. The goal was to identify the effects of climatic warming and land degradation on soil moisture (θ), soil surface temperature (Tsfc), and soil temperature (Ts). In the present study, land degradation significantly reduced θ by 4.5-6.1% at a depth of 0-100 cm (P soil surface. Experimental warming aggravated topsoil drought caused by land degradation, intensified the magnitude of degradation, and caused a positive feedback in the degraded alpine meadow ecosystem. Therefore, an immediate need exists to restore degraded alpine meadow grasslands in the Qinghai-Tibetan Plateau in anticipation of a warmer future.

  4. What goes down must come up: symmetry in light-induced migration behaviour of Daphnia

    NARCIS (Netherlands)

    Van Gool, E.; Ringelberg, J.

    2003-01-01

    During a short period of the year, Daphnia may perform a phenotypically induced diel vertical migration. For this to happen, light-induced swimming reactions must be enhanced both at dawn and at dusk. Enhanced swimming in response to light intensity increase can be elicited by fish-associated

  5. Photoreactivation of ultraviolet light-induced sister chromatid exchanges in potorous cells

    International Nuclear Information System (INIS)

    Ishizaki, K.; Nikaido, O.; Takebe, H.

    1980-01-01

    Exposure to visible light after UV-irradiation showed a remarkable effect on UV-induced sister chromatid exchanges (SCEs). After 6-h exposure to visible light (3 x 10 5 J/m 2 ), two-thirds of the UV-induced SCEs were prevented, confirming Kato's findings. (Nature 249, 552-3, 1974) Exposure to visible light before UV irradiation had no effect. This effect of visible light on UV-induced CSEs was temperature dependent, suggesting the presence of enzymatic photoreactivation. (author)

  6. Bag3-induced autophagy is associated with degradation of JCV oncoprotein, T-Ag.

    Directory of Open Access Journals (Sweden)

    Ilker Kudret Sariyer

    Full Text Available JC virus, JCV, is a human neurotropic polyomavirus whose replication in glial cells causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML. In addition, JCV possesses oncogenic activity and expression of its transforming protein, large T-antigen (T-Ag, in several experimental animals induces tumors of neural origin. Further, the presence of JCV DNA and T-Ag have been repeatedly observed in several human malignant tissues including primitive neuroectodermal tumors and glioblastomas. Earlier studies have demonstrated that Bag3, a member of the Bcl-2-associated athanogene (Bag family of proteins, which is implicated in autophagy and apoptosis, is downregulated upon JCV infection of glial cells and that JCV T-Ag is responsible for suppressing the activity of the BAG3 promoter. Here, we investigated the possible impact of Bag3 on T-Ag expression in JCV-infected human primary glial cells as well as in cells derived from T-Ag-induced medulloblastoma in transgenic animals. Results from these studies revealed that overexpression of Bag3 drastically decreases the level of T-Ag expression by inducing the autophagic degradation of the viral protein. Interestingly, this event leads to the inhibition of JCV infection of glial cells, suggesting that the reduced levels of T-antigen seen upon the overexpression of Bag3 has a biological impact on the viral lytic cycle. Results from protein-protein interaction studies showed that T-Ag and Bag3 physically interact with each other through the zinc-finger of T-Ag and the proline rich domains of Bag3, and this interaction is important for the autophagic degradation of T-Ag. Our observations open a new avenue of research for better understanding of virus-host interaction by investigating the interplay between T-Ag and Bag3, and their impact on the development of JCV-associated diseases.

  7. Bag3-induced autophagy is associated with degradation of JCV oncoprotein, T-Ag.

    Science.gov (United States)

    Sariyer, Ilker Kudret; Merabova, Nana; Patel, Prem Kumer; Knezevic, Tijana; Rosati, Alessandra; Turco, Maria C; Khalili, Kamel

    2012-01-01

    JC virus, JCV, is a human neurotropic polyomavirus whose replication in glial cells causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). In addition, JCV possesses oncogenic activity and expression of its transforming protein, large T-antigen (T-Ag), in several experimental animals induces tumors of neural origin. Further, the presence of JCV DNA and T-Ag have been repeatedly observed in several human malignant tissues including primitive neuroectodermal tumors and glioblastomas. Earlier studies have demonstrated that Bag3, a member of the Bcl-2-associated athanogene (Bag) family of proteins, which is implicated in autophagy and apoptosis, is downregulated upon JCV infection of glial cells and that JCV T-Ag is responsible for suppressing the activity of the BAG3 promoter. Here, we investigated the possible impact of Bag3 on T-Ag expression in JCV-infected human primary glial cells as well as in cells derived from T-Ag-induced medulloblastoma in transgenic animals. Results from these studies revealed that overexpression of Bag3 drastically decreases the level of T-Ag expression by inducing the autophagic degradation of the viral protein. Interestingly, this event leads to the inhibition of JCV infection of glial cells, suggesting that the reduced levels of T-antigen seen upon the overexpression of Bag3 has a biological impact on the viral lytic cycle. Results from protein-protein interaction studies showed that T-Ag and Bag3 physically interact with each other through the zinc-finger of T-Ag and the proline rich domains of Bag3, and this interaction is important for the autophagic degradation of T-Ag. Our observations open a new avenue of research for better understanding of virus-host interaction by investigating the interplay between T-Ag and Bag3, and their impact on the development of JCV-associated diseases.

  8. Enhanced visible light photocatalytic activity of copper-doped titanium oxide-zinc oxide heterojunction for methyl orange degradation

    Science.gov (United States)

    Dorraj, Masoumeh; Alizadeh, Mahdi; Sairi, Nor Asrina; Basirun, Wan Jefrey; Goh, Boon Tong; Woi, Pei Meng; Alias, Yatimah

    2017-08-01

    A novel Cu-doped TiO2 coupled with ZnO nanoparticles (Cu-TiO2/ZnO) was prepared by sol-gel method and subsequent precipitation for methyl orange (MO) photodegradation under visible light irradiation. The compositions and shapes of the as-prepared Cu-TiO2/ZnO nanocomposites were characterized by photoluminescence spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra and Brunauer-Emmett-Teller adsorption isotherm techniques. The Cu-TiO2/ZnO nanocomposites showed considerably higher photocatalytic activity for MO removal from water under visible light irradiation than that of single-doped semiconductors. The effects of Cu-TiO2 and ZnO mass ratios on the photocatalytic reaction were also studied. A coupling percentage of 30% ZnO exhibited the highest photocatalytic activity. The enhanced photocatalytic activity of the Cu-TiO2/ZnO nanocomposites was mainly attributed to heterojunction formation, which allowed the efficient separation of photoinduced electron-hole pairs at the interface. Moreover, these novel nanocomposites could be recycled during MO degradation in a three-cycle experiment without evident deactivation, which is particularly important in environmental applications.

  9. Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    SU Bitao; WANG Ke; BAI Jie; MU Hongmei; TONG Yongchun; MIN Shixiong; SHE Shixiong; LEI Ziqiang

    2007-01-01

    Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3+/TiO2 nanoparticles under visible light irradia-tion. The influence of doping amount of Fe3+ (ω: 0.00%-3.00%) on photocatalytic activities of TiO2 was investigated.Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorptionspectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.

  10. Enhanced visible-light-response photocatalytic degradation of methylene blue on Fe-loaded BiVO{sub 4} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Chala, Sinaporn [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wetchakun, Khatcharin [Program of Physics, Faculty of Science, Ubon Ratchathani Rajabhat University, Ubon Ratchathani 34000 (Thailand); Phanichphant, Sukon [Materials Science Research Centre, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Inceesungvorn, Burapat [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wetchakun, Natda, E-mail: natda_we@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-06-01

    Highlights: • Fe-loaded BiVO{sub 4} particles were prepared by hydrothermal method. • Physicochemical properties played a significant role in photocatalytic process. • All Fe-loaded BiVO{sub 4} samples showed higher photocatalytic activity than pure BiVO{sub 4}. • The Fe{sup 3+} ions may improve the separation of photogenerated electrons and holes. - Abstract: Pure BiVO{sub 4} and nominal 0.5–5.0 mol% Fe-loaded BiVO{sub 4} samples were synthesized by hydrothermal method. All samples were characterized in order to obtain the correlation between structure and photocatalytic properties by X-ray diffraction, Brunauer, Emmett and Teller, UV–vis diffuse reflectance spectrophotometry, photoluminescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma-optical emission spectroscopy. The structure of all samples was single-phase monoclinic scheelite. The absorption spectrum of 5.0 mol% Fe-loaded BiVO{sub 4} shifted to the visible region, suggesting the potential application of this material as a superior visible-light driven photocatalyst in comparison with pure BiVO{sub 4}. Photocatalytic activities of all photocatalyst samples were examined by studying the degradation of methylene blue under visible light irradiation. The results clearly showed that Fe-loaded BiVO{sub 4} sample exhibited remarkably higher activity than pure BiVO{sub 4}.

  11. Catalytic degradation of Acid Orange 7 by manganese oxide octahedral molecular sieves with peroxymonosulfate under visible light irradiation.

    Science.gov (United States)

    Duan, Lian; Sun, Binzhe; Wei, Mingyu; Luo, Shilu; Pan, Fei; Xu, Aihua; Li, Xiaoxia

    2015-03-21

    In this paper, the photodegradation of Acid Orange 7 (AO7) in aqueous solutions with peroxymonosulfate (PMS) was studied with manganese oxide octahedral molecular sieves (OMS-2) as the catalyst. The activities of different systems including OMS-2 under visible light irradiation (OMS-2/Vis), OMS-2/PMS and OMS-2/PMS/Vis were evaluated. It was found that the efficiency of OMS-2/PMS was much higher than that of OMS-2/Vis and could be further enhanced by visible light irradiation. The catalyst also exhibited stable performance for multiple runs. Results from ESR and XPS analyses suggested that the highly catalytic activity of the OMS-2/PMS/Vis system possible involved the activation of PMS to sulfate radicals meditated by the redox pair of Mn(IV)/Mn(III) and Mn(III)/Mn(II), while in the OMS-2/PMS system, only the redox reaction between Mn(IV)/Mn(III) occurred. Several operational parameters, such as dye concentration, catalyst load, PMS concentration and solution pH, affected the degradation of AO7. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Enhanced visible-light-response photocatalytic degradation of methylene blue on Fe-loaded BiVO4 photocatalyst

    International Nuclear Information System (INIS)

    Chala, Sinaporn; Wetchakun, Khatcharin; Phanichphant, Sukon; Inceesungvorn, Burapat; Wetchakun, Natda

    2014-01-01

    Highlights: • Fe-loaded BiVO 4 particles were prepared by hydrothermal method. • Physicochemical properties played a significant role in photocatalytic process. • All Fe-loaded BiVO 4 samples showed higher photocatalytic activity than pure BiVO 4 . • The Fe 3+ ions may improve the separation of photogenerated electrons and holes. - Abstract: Pure BiVO 4 and nominal 0.5–5.0 mol% Fe-loaded BiVO 4 samples were synthesized by hydrothermal method. All samples were characterized in order to obtain the correlation between structure and photocatalytic properties by X-ray diffraction, Brunauer, Emmett and Teller, UV–vis diffuse reflectance spectrophotometry, photoluminescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma-optical emission spectroscopy. The structure of all samples was single-phase monoclinic scheelite. The absorption spectrum of 5.0 mol% Fe-loaded BiVO 4 shifted to the visible region, suggesting the potential application of this material as a superior visible-light driven photocatalyst in comparison with pure BiVO 4 . Photocatalytic activities of all photocatalyst samples were examined by studying the degradation of methylene blue under visible light irradiation. The results clearly showed that Fe-loaded BiVO 4 sample exhibited remarkably higher activity than pure BiVO 4

  13. Degradation of lipids in yeast (Saccharomyces cerevisiae) at the early phase of organic solvent-induced autolysis

    International Nuclear Information System (INIS)

    Ishida-Ichimasa, Michiko

    1978-01-01

    Initial stage of organic solvent-induced autolysis in yeast was studied with 14 C-acetate labeled cells. In the case of toluene-induced autolysis, primary cell injury which was estimated by leakage of UV absorbing substances from cell accompanied rapid deacylation of phospholipids. Lysophospholipids did not occur during autolysis. When autolysis was induced by addition of ethyl acetate, phospholipids of yeast cells were not degraded so much. Ethyl acetate rather inhibited yeast phospholipase activity under the condition tested. (auth.)

  14. Light induced cooling of a heated solid immersed in liquid helium I

    International Nuclear Information System (INIS)

    Lezak, D.; Brodie, L.C.; Semura, J.S.

    1984-01-01

    This chapter investigates the marked enhancement in the transient heat transfer from the heater-thermometer to the liquid helium immediately following the application of a flash of visible light. This ''light effect'' is associated with increased bubble activity, and it is possible that the light induces a rapid nucleation of bubbles in the superheated liquid at or near the heater surface. A summary of the light effect is presented and some potential uses to which this effect could be applied are suggested. Quantification of the light effect and properties of the light effect are discussed. It is determined that the light effect is an additional cooling due to a light induced enhancement of boiling in superheated liquid helium I. The effect could be applied in practical cryogenic engineering and for the acquisition of fundamental knowledge of boiling heat transfer and nucleation in cryogenic liquids

  15. Fluorescent-light-induced lethality and DNA repair in normal and xeroderma pigmentosum fibroblasts

    International Nuclear Information System (INIS)

    Ritter, M.A.; Williams, J.R.

    1981-01-01

    Cell survival and induction of endonuclease-sensitive sites in DNA were measured in human fibroblast cells exposed to fluorescent light or germicidal ultraviolet light. Cells from a xeroderma pigmentosum patient were hypersensitive to cell killing by fluorescent light, although less so than for germicidal ultraviolet light. Xeroderma pigmentosum cells were deficient in the removal of fluorescent light-induced endonuclease sites that are probably pyrimidine dimers, and both the xeroderma pigmentosum and normal cells removed these sites with kinetics indistinguishable from those for ultraviolet light-induced sites. A comparison of fluorescent with ultraviolet light data demonstrates that there are markedly fewer pyrimidine dimers per lethal event for fluorescent than for ultraviolet light, suggesting a major role for non-dimer damage in fluorescent lethality. (Auth.)

  16. FT-IR study of gamma-radiation induced degradation of polyvinyl alcohol (PVA) and PVA/humic acids blends

    International Nuclear Information System (INIS)

    Ilcin, M.; Hola, O.; Bakajova, B.; Kucerik, J.

    2010-01-01

    Samples of pure polyvinyl alcohol (PVA) and PVA doped with humic acids were exposed to gamma radiation. Gamma rays induced the degradation of the pure polymer. Degradation changes were observed using ATR FT-IR equipment. Dehydration, double bond creation, and their subsequent oxidation (surrounding atmosphere was air) were found out. Also, other degradation reactions (e.g. chain scission, cyclization) occur simultaneously. Formation of C=C and C=O bonds is apparent from FT-IR spectra. In contrast the presence of humic acids in the PVA sample showed stabilizing effect on PVA structure within the concentration range 0.5-10%. (author)

  17. Light induced heterogeneous ozone processing on the pesticides adsorbed on silica particles

    Science.gov (United States)

    Socorro, J.; Désert, M.; Quivet, E.; Gligorovski, S.; Wortham, H.

    2013-12-01

    In France, in 2010, the sales of pesticides reached 1.8 billion euros for 61 900 tons of active ingredients, positioning France as a first European consumer of pesticides, as reported by the European Crop Protection Association. About 19 million hectares of crops are sprayed annually with pesticides, i.e., 35% of the total surface area of France. This corresponds to an average pesticide dose of 3.2 kg ha-1. The consumption of herbicide and fungicide is favoured in comparison to the use of insecticides in France and the other European countries, as well. The partitioning of pesticides between the gas and particulate phases influences the atmospheric fate of these compounds such as their photo-chemical degradation. There is much uncertainty concerning the behavior of the pesticides in the atmosphere. Especially, there is a gap of knowledge concerning the degradation of the pesticides induced by heterogeneous reactions in absence and especially in presence of solar light. Considering that most of the pesticides currently used are semi-volatile, it is of crucial importance to investigate the heterogeneous reactivity of particulate pesticides with light and with atmospheric oxidants such as ozone and OH radical. The aim of the present work is to evaluate the light induced heterogeneous ozonation of suspended pesticide particles. 8 pesticides (cyprodinil, deltamethrin, difenoconazole, fipronil, oxadiazon, pendimethalin, permethrin and tetraconazole) were chosen for their physico-chemical properties and their concentration levels in the PACA (Région Provence-Alpes-Côte d'Azur) region, France. Silica particles with well-known properties were chosen as model particles of atmospheric relevance. Kinetic rate constants were determined to allow estimate the atmospheric lifetimes relating to ozone. The rate constants were determined as follows: k = (6.6 × 0.2) 10-19, (7.2 × 0.3) 10-19, (5.1 × 0.5) 10-19, (3.9 × 0.3) 10-19 [cm3 molecules-1 s-1] for Cyprodinil

  18. Are bursts of green leaf volatile emissions from plants following light to dark transitions associated with de-novo biosynthesis of free fatty acids and not stress-induced membrane degradation? J. Norman- University of North Carolina K. Jardine- University of Arizona G. Barron-Gafford- University of Arizona

    Science.gov (United States)

    Norman, J. P.; Jardine, K. J.; Barron-Gafford, G. A.

    2011-12-01

    Green Leaf Volatiles (GLVs) are a diverse group of fatty acid-derived Volatile Organic Compounds (VOCs) emitted by all plants. These GLVs are involved in a wide variety of stress-related biological functions, as well as the formation of secondary organic aerosols and ozone in the troposphere. To date, GLV emissions have primarily been associated with acute stress responses wherein fatty acids are released from plant membranes and enzymatically oxidized to GLVs via the lipoxygenase pathway. However the biochemical role of these gases within unwounded plants has remained unknown so far. Recently, GLV emissions were reported following light-dark transitions and were hypothesized to also be related to a mechanical stress response (i.e. leaf cutting). However in this study we show that GLV emissions from mesquite trees have a separate biochemical pathway for their production that is unrelated to stress. GLV emission rates following light-dark transitions were quantified from young and mature Mesquite branches. It was found that young branches had very high photosynthetic rates and displayed strong bursts of a wide array of GLVs following darkening, while mature branches had much lower photosynthetic rates showed much weaker or no bursts. This is interesting because neither the mature nor the juvenile plants were subjected to any type of stress during measurement. Moreover, the older plant samples (which had the lower emissions) were collected by clipping branches from a tree and re-clipping their stems under water. Given what has previously been established concerning the relationship of GLV emissions to mechanical stress, one would expect these older branches to have higher emissions than their juvenile counterparts rather than lower emissions. We speculate that the emission of GLVs during light-dark transitions is not the result of a stress response, but rather the result of rapid de-novo fatty acid biosynthesis occurring in chloroplasts of young branches fed by a

  19. Construction of PAH-degrading mixed microbial consortia by induced selection in soil.

    Science.gov (United States)

    Zafra, German; Absalón, Ángel E; Anducho-Reyes, Miguel Ángel; Fernandez, Francisco J; Cortés-Espinosa, Diana V

    2017-04-01

    Bioremediation of polycyclic aromatic hydrocarbons (PAHs)-contaminated soils through the biostimulation and bioaugmentation processes can be a strategy for the clean-up of oil spills and environmental accidents. In this work, an induced microbial selection method using PAH-polluted soils was successfully used to construct two microbial consortia exhibiting high degradation levels of low and high molecular weight PAHs. Six fungal and seven bacterial native strains were used to construct mixed consortia with the ability to tolerate high amounts of phenanthrene (Phe), pyrene (Pyr) and benzo(a)pyrene (BaP) and utilize these compounds as a sole carbon source. In addition, we used two engineered PAH-degrading fungal strains producing heterologous ligninolytic enzymes. After a previous selection using microbial antagonism tests, the selection was performed in microcosm systems and monitored using PCR-DGGE, CO 2 evolution and PAH quantitation. The resulting consortia (i.e., C1 and C2) were able to degrade up to 92% of Phe, 64% of Pyr and 65% of BaP out of 1000 mg kg -1 of a mixture of Phe, Pyr and BaP (1:1:1) after a two-week incubation. The results indicate that constructed microbial consortia have high potential for soil bioremediation by bioaugmentation and biostimulation and may be effective for the treatment of sites polluted with PAHs due to their elevated tolerance to aromatic compounds, their capacity to utilize them as energy source. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Methadone induces CAD degradation and AIF-mediated necrotic-like cell death in neuroblastoma cells.

    Science.gov (United States)

    Perez-Alvarez, Sergio; Iglesias-Guimarais, Victoria; Solesio, María E; Melero-Fernandez de Mera, Raquel María; Yuste, Víctor J; Galindo, María F; Jordán, Joaquín

    2011-04-01

    Methadone (d,l-methadone hydrochloride) is a full-opioid agonist, originally developed as a substitution for heroin or other opiates abusers. Nowadays methadone is also being applied as long-lasting analgesics in cancer, and it is proposed as a promising agent for leukemia therapy. Previously, we have demonstrated that high concentrations of methadone (0.5mM) induced necrotic-like cell death in SH-SY5Y cells. The pathway involved is caspase-independent but involves impairment of mitochondrial ATP synthesis and mitochondrial cytochrome c release. However, the downstream mitochondrial pathways remained unclear. Here, we studied the participation of apoptosis inducing factor (AIF) in methadone-induced cell death. Methadone resulted in a translocation of AIF from mitochondria to the nucleus. Translocation was inhibited by cyclosporine A, but not by lack of Bax protein. Therefore the effect seems mediated by the formation of the mitochondrial transition pore, but is apparently independent of Bax. Furthermore, methadone-treated SH-SY5Y nuclei show characteristics that are typical for stage I nuclear condensation. Methadone did not induce degradation of DNA into oligonucleosomal fragments or into high molecular weight DNA fragments. Absence of DNA fragmentation coincided with a considerable decrease in the levels of the caspase-actived endonuclase DNase and its chaperone-inhibitor ICAD. In conclusion, our results provide mechanistic insights into the molecular mechanisms that underlie methadone-induced cell death. This knowledge may prove useful to develop novel strategies to prevent toxic side-effects of methadone thereby sustaining its use as therapeutical agent against tumors. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Analytical Characterization of SPM Impact on XPM-Induced Degradation in Dispersion-Compensated WDM Systems

    Science.gov (United States)

    Luís, Ruben S.; Cartaxo, Adolfo V. T.

    2005-03-01

    This paper proposes the definition of a cross-phase modulation (XPM)-induced power penalty for intensity modulation/direct detection (IM-DD) systems as a function of the normalized variance of the XPM-induced IM. This allows the definition of 1-dB power penalty reference values. New expressions of the equivalent linear model transfer functions for the XPM-induced IM and phase modulation (PM) that include the influence of self-phase modulation (SPM) as well as group-velocity dispersion are derived. The new expressions allow a significant extension for higher powers and dispersion parameters of expressions derived in previous papers for single-segment and multisegment fiber systems with dispersion compensation. Good agreement between analytical results and numerical simulations is obtained. Consistency with work performed numerically and experimentally by other authors is shown, validating the proposed model. Using the proposed model, the influence of residual dispersion and SPM on the limitations imposed by XPM on the performance of dispersion-compensated systems is assessed. It is shown that inline residual dispersion may lead to performance improvement for a properly tuned total residual dispersion. The influence of SPM is shown to degrade the system performance when nonzero-dispersion-shifted fiber is used. However, systems using standard single-mode fiber may benefit from the presence of SPM.

  2. Radiation-induced microcrystal shape change as a mechanism of wasteform degradation

    Science.gov (United States)

    Ojovan, Michael I.; Burakov, Boris E.; Lee, William E.

    2018-04-01

    Experiments with actinide-containing insulating wasteforms such as devitrified glasses containing 244Cm, Ti-pyrochlore, single-phase La-monazite, Pu-monazite ceramics, Eu-monazite and zircon single crystals containing 238Pu indicate that mechanical self-irradiation-induced destruction may not reveal itself for many years (even decades). The mechanisms causing these slowly-occurring changes remain unknown therefore in addition to known mechanisms of wasteform degradation such as matrix swelling and loss of solid solution we have modelled the damaging effects of electrical fields induced by the decay of radionuclides in clusters embedded in a non-conducting matrix. Three effects were important: (i) electric breakdown; (ii) cluster shape change due to dipole interaction, and (iii) cluster shape change due to polarisation interaction. We reveal a critical size of radioactive clusters in non-conducting matrices so that the matrix material can be damaged if clusters are larger than this critical size. The most important parameters that control the matrix integrity are the radioactive cluster (inhomogeneity) size, specific radioactivity, and effective matrix electrical conductivity. We conclude that the wasteform should be as homogeneous as possible and even electrically conductive to avoid potential damage caused by electrical charges induced by radioactive decay.

  3. Effect of gamma irradiation conditions on the radiation-induced degradation of isobutylene-isoprene rubber

    Energy Technology Data Exchange (ETDEWEB)

    Sen, M. E-mail: msen@hacettepe.edu.tr; Uzun, C.; Kantoglu, Oe.; Erdogan, S.M.; Deniz, V.; Gueven, O

    2003-08-01

    The effect of gamma irradiation conditions on the radiation-induced degradation of uncrosslinked, commercial isobutylene-isoprene rubbers has been investigated in this study. Influence of dose rate and irradiation atmosphere on the degradation of butyl rubber has been followed by viscosimetric and chromatographic analyses. Limiting viscosity number of all butyl rubbers decreased sharply up to 100 kGy and leveled off at around the same molecular weight, independent of dose rate. Slightly higher decrease in viscosity was observed for samples irradiated in air than in nitrogen especially at low dose rate irradiation. Cross-linking G(X), and chain scission G(S) yields of butyl rubbers were calculated by using weight- and number-average molecular weights of irradiated rubber determined by Size Exclusion Chromatography analyses. G-value results showed that chain scission reactions in isobutylene-isoprene rubber in air atmosphere are more favorable than in nitrogen atmosphere, and that lower dose rate enhances chain scission over cross-linking.

  4. Hydride-induced degradation of hoop ductility in textured zirconium-alloy tubes: A theoretical analysis

    International Nuclear Information System (INIS)

    Qin, W.; Szpunar, J.A.; Kozinski, J.

    2012-01-01

    Hydride-induced degradation of hoop ductility in Zr-alloy tubular components has been studied for many years because of its importance in the nuclear industry. In this paper the role of intergranular and intragranular δ-hydrides in the degradation of ductility of the textured Zr-alloy tubes is investigated. The correlation among hydride distribution, orientation and morphology in the tubes is formulated based on thermodynamic modeling, and then analyzed. The results show that the applied stress, the crystallographic texture of α-Zr matrix, the grain-boundary structure, and the morphology and size of Zr grains simultaneously govern the site preference and the orientation of hydrides. A criterion is proposed to determine the threshold stress of hydride reorientation. The hoop ductility of the hydrided Zr tubes is discussed using the concept of macroscopic fracture strain. It is shown that the intergranular hydrides may be more deleterious to ductility than the intragranular ones. This work defines a general framework for understanding the relation of the microstructure of hydride-forming materials to embrittlement.

  5. Anodic deposition-assisted photoelectrocatalytic degradation of bisphenol A at a cadmium sulfide modified electrode based on visible light-driven fuel cells

    International Nuclear Information System (INIS)

    Luo, Jin-Yuan; Chen, Lin-Lin; Liang, Xing-Hui; Zhao, Qian-Wen; Li, Hong

    2015-01-01

    Highlights: • CdS nanoparticles can largely promote anodic deposition of BPA in the dark. • Photoelectrocatalytic degradation of BPA is driven by photo-stimulated fuel cells. • CdS/ITO is regenerated in photoelectrocatalytic degradation process of BPA. • Visible light-driven BPA fuel cell exhibits several unique advantages. - Abstract: A novel photoelectrocatalytic oxidation method has been successfully developed to effectively degrade bisphenol A (BPA) using a visible light-sensitive CdS nanoparticle modified indium-tin oxide (ITO) electrode. In the present protocol, BPA is oxidized on the CdS/ITO electrode to produce a redox-active film (BPA AD ), which is subsequently degraded upon incorporation of visible light irradiation and anodic electric fields, making the CdS/ITO electrode cyclically regenerated and the BPA removed. The addition of CdS nanoparticles to the ITO electrode not only increases the anodic deposition of BPA in the dark, but also promotes the photoelectrocatalytic degradation of BPA under visible light irradiation. The CdS/ITO photoanode shows high regeneration ability, and the removal efficiency of BPA is high up to 94.1%. Meanwhile, a monopolar visible light-simulated BPA fuel cell vs. Ag/AgCl electrode with a salt bridge is fabricated to achieve the photoelectrocatalytic degradation of BPA, showing open-circuit photovoltage of 0.412 (±0.015) V and short-circuit photocurrent density of 20.52 (±1.02) μA cm −2 , respectively. The present study provides a new approach for efficient removal of phenolic pollutants and optimum utilization of renewable energy sources.

  6. Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor - 1 alpha protein in hypoxic conditions

    International Nuclear Information System (INIS)

    Wang, Ronghai; Zhang, Ping; Li, Jinhang; Guan, Hongzai; Shi, Guangjun

    2016-01-01

    The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG–HIF–1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. - Highlights: • HIF-1α protein is constitutively degraded in hypoxic conditions. • Requirement of ubiquitination for HIF-1α degradation in hypoxia. • Hypoxic HIF-1α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization.

  7. Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor - 1 alpha protein in hypoxic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ronghai [Department of Urology, Linzi District People' s Hospital, Zibo, 255400 (China); Zhang, Ping, E-mail: zpskx001@163.com [Department of Gynecology, Qingdao Municipal Hospital, Qingdao, 266011 (China); Li, Jinhang [Department of Gynecology, Qingdao Municipal Hospital, Qingdao, 266011 (China); Guan, Hongzai [Laboratory Department, School of Medicine, Qingdao University, Qingdao, 266071 (China); Shi, Guangjun, E-mail: qdmhshigj@yahoo.com [Department of Hepatobiliary Surgery, Qingdao Municipal Hospital, Qingdao, 266071 (China)

    2016-01-29

    The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG–HIF–1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. - Highlights: • HIF-1α protein is constitutively degraded in hypoxic conditions. • Requirement of ubiquitination for HIF-1α degradation in hypoxia. • Hypoxic HIF-1α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization.

  8. Effect of degradative plasmid CAM-OCT on responses of Pseudomonas bacteria to UV light

    International Nuclear Information System (INIS)

    McBeth, D.L.

    1989-01-01

    The effect of plasmid CAM-OCT on responses to UV irradiation was compared in Pseudomonas aeruginosa, in Pseudomonas putida, and in Pseudomonas putida mutants carrying mutations in UV response genes. CAM-OCT substantially increased both survival and mutagenesis in the two species. P. aeruginosa strains without CAM-OCT exhibited much higher UV sensitivity than did P. putida strains. UV-induced mutagenesis of plasmid-free P. putida was easily detected in three different assays (two reversion assays and one forward mutation assay), whereas UV mutagenesis of P. aeruginosa without CAM-OCT was seen only in the forward mutation assay. These results suggest major differences in DNA repair between the two species and highlight the presence of error-prone repair functions on CAM-OCT. A number of P. putida mutants carrying chromosomal mutations affecting either survival or mutagenesis after UV irradiation were isolated, and the effect of CAM-OCT on these mutants was determined. All mutations producing a UV-sensitive phenotype in P. putida were fully suppressed by the plasmid, whereas the plasmid had a more variable effect on mutagenesis mutations, suppressing some and producing no suppression of others. On the basis of the results reported here and results obtained by others with plasmids carrying UV response genes, it appears that CAM-OCT may differ either in regulation or in the number and functions of UV response genes encoded

  9. Plasma-induced surface degradation in 304 stainless steel used for TRIAM-1M limiter

    International Nuclear Information System (INIS)

    Tsukuda, N.; Kuramoto, E.; Tokunaga, K.; Muroga, T.; Yoshida, N.; Itoh, S.

    1994-01-01

    Surface degradation in a 304 stainless steel limiter of TRIAM-1M by long-pulse discharge during long period operation has been examined by means of X-ray diffraction, scanning electron microscopy and dynamical microindentation tests. Particular exfoliation and hardening of the surface of the electron drift side were observed. These result from the formation of α prime martensite induced by hydrogen in the plasma. The stability of the martensitic phase has been studied by annealing experiments on the cathodically hydrogen charged 316 stainless steel by X-ray diffraction. Both ε and α prime martensites were formed by 22 h cathodic charging. The former reverts to γ-phase and/or converts to α prime martensite below 723 K and the latter reverts to γ-phase below 923 K, repectively. ((orig.))

  10. Potential-Induced Degradation-Delamination Mode in Crystalline Silicon Modules: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kempe, Michael D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wohlgemuth, John [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Li, Jichao [SunPower Corporation; Shen, Yu-Chen [SunPower Corporation

    2018-03-21

    A test sequence producing potential-induced degradation-delamination (PID-d) in crystalline silicon modules has been tested and found comparable under visual inspection to cell/encapsulant delamination seen in some fielded modules. Four commercial modules were put through this sequence, 85 degrees C, 85%, 1000 h damp heat, followed by an intensive PID stress sequence of 72 degrees C, 95% RH, and -1000 V, with the module face grounded using a metal foil. The 60 cell c-Si modules exhibiting the highest current transfer (4.4 center dot 10-4 A) exhibited PID-d at the first inspection after 156 h of PID stress. Effects promoting PID-d are reduced adhesion caused by damp heat, sodium migration further reducing adhesion to the cells, and gaseous products of electrochemical reactions driven by the applied system voltage. A new work item proposal for an IEC test standard to evaluate for PID-d is anticipated.

  11. Enhanced photocatalytic degradation of norfloxacin in aqueous Bi{sub 2}WO{sub 6} dispersions containing nonionic surfactant under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Lin, E-mail: tanglin@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Wang, Jiajia [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zeng, Guangming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

    2016-04-05

    Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi{sub 2}WO{sub 6} dispersions under visible light irradiation (400–750 nm). • Cu{sup 2+} (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi{sub 2}WO{sub 6} was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi{sub 2}WO{sub 6} dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi{sub 2}WO{sub 6} surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

  12. Fabrication of efficient visible light activated Cu–P25–graphene ternary composite for photocatalytic degradation of methyl blue

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Zheng [Department of Chemistry, School of Science, Beijing Jiaotong University, Beijing 100044 (China); Duan, Wubiao, E-mail: wbduan@bjtu.edu.cn [Department of Chemistry, School of Science, Beijing Jiaotong University, Beijing 100044 (China); Liu, Bo; Chen, Xidong [Department of Chemistry, School of Science, Beijing Jiaotong University, Beijing 100044 (China); Yang, Feihua; Guo, Jianping [State Key Laboratory of Solid Wastes Resource Utilization and Energy Saving Building Materials, Beijing Building Materials Academy of Sciences Research, Beijing 100041 (China)

    2015-11-30

    Graphical abstract: This enhanced photocatalytic activity of multi-doped P25 arises due to the synergistic effect of dopants contribution to improve visible light absorption and increase of the lifetime of photo-generated charge carriers. Plausible mechanism for the photocatalytic degradation of MB on CPG nanocomposite is illustrated in the figure above. Graphene incooperated with TiO{sub 2} promotes the formation of Ti−C or Ti−O−C bonds that introduced an additional energy level above the valence band of TiO{sub 2}. Furthermore, copper and graphene serve as an inhibitor of recombination by trapping electrons to promote charge separation. Simultaneously, doping Cu{sup 2+} ions into TiO{sub 2} could also induce more oxygen vacancies, which can produce more hydroxyl groups. Finally, the enhanced adsorptivity of π–π interaction between MB and the composite catalyst was as well significant for photocatalytic activity. - Highlights: • Hydrothermal method was proposed to fabricate Cu–P25–graphene ternary composite at relative low temperature. • Degradation efficiency and hydrogen evolution rate of CPG-4 was up to 98% and 1.90 mmol g{sup −1} respectively. • The efficiency of MB removal by CPG-4 was sustainable and consistent. • The particles-on-a-sheet structure and synergistic effects of Cu{sup 2+} ions and GO lead to the improved photocatalytic activity. • The effects of pH values of methyl blue solution for photocatalysts was investigated. - Abstract: Cu–P25–graphene nanocomposite was fabricated through hydrothermal method at relatively low temperature. The technique used is P25–graphene (PG) binary composite was firstly prepared by P25 and graphite oxide (GO), and then Cu{sup 2+} ions were impregnated into PG composite. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance

  13. Blue light filtered white light induces depression-like responses and temporary spatial learning deficits in rats.

    Science.gov (United States)

    Meng, Qinghe; Lian, Yuzheng; Jiang, Jianjun; Wang, Wei; Hou, Xiaohong; Pan, Yao; Chu, Hongqian; Shang, Lanqin; Wei, Xuetao; Hao, Weidong

    2018-04-18

    Ambient light has a vital impact on mood and cognitive functions. Blue light has been previously reported to play a salient role in the antidepressant effect via melanopsin. Whether blue light filtered white light (BFW) affects mood and cognitive functions remains unclear. The present study aimed to investigate whether BFW led to depression-like symptoms and cognitive deficits including spatial learning and memory abilities in rats, and whether they were associated with the light-responsive function in retinal explants. Male Sprague-Dawley albino rats were randomly divided into 2 groups (n = 10) and treated with a white light-emitting diode (LED) light source and BFW light source, respectively, under a standard 12 : 12 h L/D condition over 30 days. The sucrose consumption test, forced swim test (FST) and the level of plasma corticosterone (CORT) were employed to evaluate depression-like symptoms in rats. Cognitive functions were assessed by the Morris water maze (MWM) test. A multi-electrode array (MEA) system was utilized to measure electro-retinogram (ERG) responses induced by white or BFW flashes. The effect of BFW over 30 days on depression-like responses in rats was indicated by decreased sucrose consumption in the sucrose consumption test, an increased immobility time in the FST and an elevated level of plasma CORT. BFW led to temporary spatial learning deficits in rats, which was evidenced by prolonged escape latency and swimming distances in the spatial navigation test. However, no changes were observed in the short memory ability of rats treated with BFW. The micro-ERG results showed a delayed implicit time and reduced amplitudes evoked by BFW flashes compared to the white flash group. BFW induces depression-like symptoms and temporary spatial learning deficits in rats, which might be closely related to the impairment of light-evoked output signals in the retina.

  14. Preparation of Ag deposited TiO2 (Ag/TiO2) composites and investigation on visible-light photocatalytic degradation activity in magnetic field

    Science.gov (United States)

    Zhang, L.; Ma, C. H.; Wang, J.; Li, S. G.; Li, Y.

    2014-12-01

    In this study, Ag deposited TiO2 (Ag/TiO2) composites were prepared by three different methods (Ultraviolet Irradiation Deposition (UID), Vitamin C Reduction (VCR) and Sodium Borohydride Reduction (SBR)) for the visible-light photocatalytic degradation of organic dyes in magnetic field. And then the prepared Ag deposited TiO2 (Ag/TiO2) composites were characterized physically by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The visible-light photocatalytic activities of these three kinds of Ag deposited TiO2 (Ag/TiO2) composites were examined and compared through the degradation of several organic dyes under visible-light irradiation in magnetic field. In addition, some influence factors such as visible-light irradiation time, organic dye concentration, revolution speed, magnetic field intensity and organic dye kind on the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composite were reviewed. The research results showed that the presence of magnetic field significantly enhanced the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composites and then contributed to the degradation of organic dyes.

  15. Light-dependent expression of flg22-induced defense genes in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Satoshi eSano

    2014-10-01

    Full Text Available Chloroplasts have been reported to generate retrograde immune signals that activate defense gene expression in the nucleus. However, the roles of light and photosynthesis in plant immunity remain largely elusive. In this study, we evaluated the effects of light on the expression of defense genes induced by flg22, a peptide derived from bacterial flagellins which acts as a potent elicitor in plants. Whole-transcriptome analysis of flg22-treated Arabidopsis thaliana seedlings under light and dark conditions for 30 min revealed that a number of (30% genes strongly induced by flg22 (>4.0 require light for their rapid expression, whereas flg22-repressed genes include a significant number of genes that are down-regulated by light. Furthermore, light is responsible for the flg22-induced accumulation of salicylic acid, indicating that light is indispensable for basal defense responses in plants. To elucidate the role of photosynthesis in defense, we further examined flg22-induced defense gene expression in the presence of specific inhibitors of photosynthetic electron transport: 3-(3,4-dichlorophenyl-1,1-dimethylurea (DCMU and 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone (DBMIB. Light-dependent expression of defense genes was largely suppressed by DBMIB, but only partially suppressed by DCMU. These findings suggest that photosynthetic electron flow plays a role in controling the light-dependent expression of flg22-inducible defense genes.

  16. Degradation of antibiotic norfloxacin in aqueous solution by visible-light-mediated C-TiO2 photocatalysis

    International Nuclear Information System (INIS)

    Chen, Meijuan; Chu, W.

    2012-01-01

    Highlights: ► Vis/C-TiO 2 process was employed to degrade norfloxacin for the first time. ► An original schematic diagram for deciphering the catalyst surface property was proposed. ► OH· radicals are verified to play a major role in the norfloxacin decomposition. ► Hole scavenger of ammonium did not show negative influence. ► Fluoride presented a unique restriction in the norfloxacin decay. - Abstract: A visible-light-mediated C-TiO 2 photocatalytic process (Vis/C-TiO 2 ) was employed to degrade antibiotic norfloxacin. The influences of catalyst dosage, initial probe compound concentration and solution pH levels on the decay performance and reaction kinetics were investigated and optimized. Based on the experimental results, an equation was established to predict the observed rate constant under neutral pH. In addition, the decay rate was accelerated under weak alkali in the presence of moderate OH − anions. Hydroxyl radical was confirmed to play a major role in the Vis/TiO 2 process, where in the presence of ·OH quencher and electron acceptor, retardation and improvement were found respectively. Furthermore, an original schematic diagram describing the surface property of C-TiO 2 was built and further verified, in which, NH 4 + cations normally served as hole scavengers showed a negligible effect because the adsorbed OH − formed a barrier for NH 4 + ions to approach the holes, and the F − anions presented a significant suppression on norfloxacin decay due to the formation of hydrogen bond (O-H⋯F) around the C-TiO 2 surface. Besides, the recycling and sedimentation tests justified that the Vis/C-TiO 2 process is a cost-effective and feasible way for wastewater treatment.

  17. Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

    Energy Technology Data Exchange (ETDEWEB)

    Hazarika, Deepshikha; Karak, Niranjan, E-mail: karakniranjan@gmail.com

    2016-07-15

    Highlights: • Nitrogen containing carbon dot and carbon dot/TiO{sub 2} nanohybrid (CD@TiO{sub 2}) are synthesized without any additional doping of passivating agent. • The photocatalytic efficacy of CD@TiO{sub 2} is found to be the best as compared to the bare TiO{sub 2}, CD and nanohybrid of TiO{sub 2} in presence of carbon dot. • Up-conversion luminescence of CD promotes the degradation activity of synthesized CD@TiO{sub 2} under visible light. • The hazardous contaminants like phenol, benzene and pesticide are efficiently degraded by CD@TiO{sub 2} under normal sunlight. - Abstract: In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO{sub 2}) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO{sub 2} and nanohybrid of TiO{sub 2} in presence of CD (CD/TiO{sub 2}) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO{sub 2}, CD@TiO{sub 2} and CD/TiO{sub 2} were examined by Fourier transform infrared (FTIR), UV–vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO{sub 2} nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO{sub 2} were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO{sub 2} exhibited the most promising photocatalytic degradation of organic

  18. Photocatalytic degradation of organic contaminants under solar light using carbon dot/titanium dioxide nanohybrid, obtained through a facile approach

    International Nuclear Information System (INIS)

    Hazarika, Deepshikha; Karak, Niranjan

    2016-01-01

    Highlights: • Nitrogen containing carbon dot and carbon dot/TiO 2 nanohybrid (CD@TiO 2 ) are synthesized without any additional doping of passivating agent. • The photocatalytic efficacy of CD@TiO 2 is found to be the best as compared to the bare TiO 2 , CD and nanohybrid of TiO 2 in presence of carbon dot. • Up-conversion luminescence of CD promotes the degradation activity of synthesized CD@TiO 2 under visible light. • The hazardous contaminants like phenol, benzene and pesticide are efficiently degraded by CD@TiO 2 under normal sunlight. - Abstract: In the present study, a novel, simple and green method was developed to synthesize highly luminescent nitrogen containing carbon dot (CD) using carbon resources like bio-based citric acid and glycerol in the presence of cost free cow urine. The as-synthesized CD showed exciting wavelength dependent down- and up-conversion flourescence properties. To utilize the advantage of up-conversion flourescence, a nanohybrid (CD@TiO 2 ) was synthesized from the above carbon resources and titanium butoxide through a facile one pot single step hydrothermal protocol. Nanomaterials like bare TiO 2 and nanohybrid of TiO 2 in presence of CD (CD/TiO 2 ) were also synthesized for comparison purpose. The optical properties and structural characteristics of the prepared CD, bare TiO 2 , CD@TiO 2 and CD/TiO 2 were examined by Fourier transform infrared (FTIR), UV–vis and fluorescence spectroscopic, scanning electron microscopic (SEM), transmission electron microscopic (TEM) and X-ray diffraction (XRD) studies. The elemental compositions of bare CD and CD@TiO 2 nanohybrid were obtained from EDX analyses. The poor crystalline nature and narrow distribution of spherical CD and anatase form of TiO 2 were confirmed from XRD and TEM studies. Amongst the studied nanomaterials, CD@TiO 2 exhibited the most promising photocatalytic degradation of organic pollutants like benzene and phenol as well as an anthrogenic pesticide under sunlight.

  19. Light-induced modification of plant plasma membrane ion transport.

    Science.gov (United States)

    Marten, I; Deeken, R; Hedrich, R; Roelfsema, M R G

    2010-09-01

    Light is not only the driving force for electron and ion transport in the thylakoid membrane, but also regulates ion transport in various other membranes of plant cells. Light-dependent changes in ion transport at the plasma membrane and associated membrane potential changes have been studied intensively over the last century. These studies, with various species and cell types, revealed that apart from regulation by chloroplasts, plasma membrane transport can be controlled by phytochromes, phototropins or channel rhodopsins. In this review, we compare light-dependent plasma membrane responses of unicellular algae (Eremosphaera and Chlamydomonas), with those of a multicellular alga (Chara), liverworts (Conocephalum), mosses (Physcomitrella) and several angiosperm cell types. Light-dependent plasma membrane responses of Eremosphaera and Chara are characterised by the dominant role of K(+) channels during membrane potential changes. In most other species, the Ca(2+)-dependent activation of plasma membrane anion channels represents a general light-triggered event. Cell type-specific responses are likely to have evolved by modification of this general response or through the development of additional light-dependent signalling pathways. Future research to elucidate these light-activated signalling chains is likely to benefit from the recent identification of S-type anion channel genes and proteins capable of regulating these channels.

  20. GPS tracking for mapping seabird mortality induced by light pollution.

    Science.gov (United States)

    Rodríguez, Airam; Rodríguez, Beneharo; Negro, Juan J

    2015-06-02

    Light pollution and its consequences on ecosystems are increasing worldwide. Knowledge on the threshold levels of light pollution at which significant ecological impacts emerge and the size of dark refuges to maintain natural nocturnal processes is crucial to mitigate its negative consequences. Seabird fledglings are attracted by artificial lights when they leave their nest at night, causing high mortality. We used GPS data-loggers to track the flights of Cory's shearwater Calonectris diomedea fledglings from nest-burrows to ground, and to evaluate the light pollution levels of overflown areas on Tenerife, Canary Islands, using nocturnal, high-resolution satellite imagery. Birds were grounded at locations closer than 16 km from colonies in their maiden flights, and 50% were rescued within a 3 km radius from the nest-site. Most birds left the nests in the first three hours after sunset. Rescue locations showed radiance values greater than colonies, and flight distance was positively related to light pollution levels. Breeding habitat alteration by light pollution was more severe for inland colonies. We provide scientific-based information to manage dark refuges facilitating that fledglings from inland colonies reach the sea successfully. We also offer methodological approaches useful for other critically threatened petrel species grounded by light pollution.

  1. Hierarchical nanostructures assembled from ultrathin Bi2WO6 nanoflakes and their visible-light induced photocatalytic property

    International Nuclear Information System (INIS)

    Wang, Xiong; Tian, Peng; Lin, Ying; Li, Li

    2015-01-01

    Graphical abstract: Hierarchical Bi 2 WO 6 nanostructures assembled from nanoflakes were successfully synthesized by a facile hydrothermal method. The excellent photocatalytic activity and recycling performance might be mainly ascribed to the unique hierarchical nanostructures and are expected to offer the nanostructures promising applications in the field of wastewater treatment. - Highlights: • Hierarchical Bi 2 WO 6 nanostructures assembled from nanoflakes were successfully synthesized by a facile hydrothermal method. • Visible-light-induced photocatalytic efficiency of the obtained nanoarchitectures was enhanced about 6 times. • A possible mechanism was proposed. - Abstract: With the aid of ethylene glycol and sodium dodecylbenzene sulfonate, the hierarchical Bi 2 WO 6 nanoarchitectures assembled from nanoflakes could be attained by a facile solvothermal method. The synthetic strategy is versatile and environmentally friendly and a plausible growth-assembly process was proposed for the formation of the hierarchical nanostructures. The visible-light-irradiated photocatalytic activity was estimated by the degradation of rhodamine B. Compared with the sample prepared by a solid-state reaction, the visible-light-induced photocatalytic efficiency of the nanostructures was enhanced about 6 times. The photocatalysis tests show that the nanostructures exhibit excellent photocatalytic activity and recycling performance, which were mainly ascribed to the unique hierarchical nanostructures and are expected to offer promising applications in the field of wastewater treatment

  2. NAD(P)H quinone oxidoreductase 1 inhibits the proteasomal degradation of homocysteine-induced endoplasmic reticulum protein

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Tomoji, E-mail: t-maeda@nichiyaku.ac.jp [Department of Neuroscience, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba-Cho, Shiwagun, Iwate, 028-3603 (Japan); Tanabe-Fujimura, Chiaki; Fujita, Yu; Abe, Chihiro; Nanakida, Yoshino; Zou, Kun; Liu, Junjun; Liu, Shuyu [Department of Neuroscience, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba-Cho, Shiwagun, Iwate, 028-3603 (Japan); Nakajima, Toshihiro [Institute of Medical Science, Tokyo Medical University, 6-1-1 Shinjyuku, Shinjyuku, Tokyo, Tokyo, 160-8402 (Japan); Komano, Hiroto, E-mail: hkomano@iwate-med.ac.jp [Department of Neuroscience, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba-Cho, Shiwagun, Iwate, 028-3603 (Japan)

    2016-05-13

    Homocysteine-induced endoplasmic reticulum (ER) protein (Herp) is an ER stress-inducible key regulatory component of ER-associated degradation (ERAD) that has been implicated in insulin hypersecretion in diabetic mouse models. Herp expression is tightly regulated. Additionally, Herp is a highly labile protein and interacts with various proteins, which are characteristic features of ubiquitinated protein. Previously, we reported that ubiquitination is not required for Herp degradation. In addition, we found that the lysine residues of Herp (which are ubiquitinated by E3 ubiquitin ligase) are not sufficient for regulation of Herp degradation. In this study, we found that NAD(P)H quinone oxidoreductase 1 (NQO1)-mediated targeting of Herp to the proteasome was involved in Herp degradation. In addition, we found that Herp protein levels were markedly elevated in synoviolin-null cells. The E3 ubiquitin ligase synoviolin is a central component of ERAD and is involved in the degradation of nuclear factor E2-related factor-2 (Nrf2), which regulates cellular reactive oxygen species. Additionally, NQO1 is a target of Nrf2. Thus, our findings indicated that NQO1 could stabilize Herp protein expression via indirect regulation of synoviolin. -- Highlights: •Herp interacts with NQO1. •NQO1 regulates Herp degradation.

  3. NAD(P)H quinone oxidoreductase 1 inhibits the proteasomal degradation of homocysteine-induced endoplasmic reticulum protein

    International Nuclear Information System (INIS)

    Maeda, Tomoji; Tanabe-Fujimura, Chiaki; Fujita, Yu; Abe, Chihiro; Nanakida, Yoshino; Zou, Kun; Liu, Junjun; Liu, Shuyu; Nakajima, Toshihiro; Komano, Hiroto

    2016-01-01

    Homocysteine-induced endoplasmic reticulum (ER) protein (Herp) is an ER stress-inducible key regulatory component of ER-associated degradation (ERAD) that has been implicated in insulin hypersecretion in diabetic mouse models. Herp expression is tightly regulated. Additionally, Herp is a highly labile protein and interacts with various proteins, which are characteristic features of ubiquitinated protein. Previously, we reported that ubiquitination is not required for Herp degradation. In addition, we found that the lysine residues of Herp (which are ubiquitinated by E3 ubiquitin ligase) are not sufficient for regulation of Herp degradation. In this study, we found that NAD(P)H quinone oxidoreductase 1 (NQO1)-mediated targeting of Herp to the proteasome was involved in Herp degradation. In addition, we found that Herp protein levels were markedly elevated in synoviolin-null cells. The E3 ubiquitin ligase synoviolin is a central component of ERAD and is involved in the degradation of nuclear factor E2-related factor-2 (Nrf2), which regulates cellular reactive oxygen species. Additionally, NQO1 is a target of Nrf2. Thus, our findings indicated that NQO1 could stabilize Herp protein expression via indirect regulation of synoviolin. -- Highlights: •Herp interacts with NQO1. •NQO1 regulates Herp degradation.

  4. p38-MK2 signaling axis regulates RNA metabolism after UV-light-induced DNA damage

    DEFF Research Database (Denmark)

    Borisova, Marina E; Voigt, Andrea; Tollenaere, Maxim A X

    2018-01-01

    quantitative phosphoproteomics and protein kinase inhibition to provide a systems view on protein phosphorylation patterns induced by UV light and uncover the dependencies of phosphorylation events on the canonical DNA damage signaling by ATM/ATR and the p38 MAP kinase pathway. We identify RNA-binding proteins......Ultraviolet (UV) light radiation induces the formation of bulky photoproducts in the DNA that globally affect transcription and splicing. However, the signaling pathways and mechanisms that link UV-light-induced DNA damage to changes in RNA metabolism remain poorly understood. Here we employ...

  5. Light induced modulation instability of surfaces under intense illumination

    KAUST Repository

    Burlakov, V. M.; Foulds, Ian G.; Goriely, A.

    2013-01-01

    heated by radiation. Periodic heating is due to focusing-defocusing effects caused by the initial surface modulation. The surface modulation has a period longer than the excitation wavelength and does not require coherent light source. Therefore

  6. Lighting.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  7. Nanotechnology in environmental remediation: degradation of volatile organic compounds (VOCs) over visible-light-active nanostructured materials.

    Science.gov (United States)

    Selvaraj, Rengaraj; Al-Kindy, Salma M Z; Silanpaa, Mika; Kim, Younghun

    2014-01-01

    Volatile organic compounds (VOCs) are major pollutants and are considered to be one of the most important contaminants generated by human beings living in urban and industrial areas. Methyl tert-butyl ether (MTBE) is a VOC that has been widely used as a gasoline additive to reduce VOC emissions from motor vehicles. However, new gasoline additives like MTBE are having negative environmental impacts. Recent survey reports clearly show that groundwater is often polluted owing to leakage of petroleum products from underground storage tanks. MTBE is highly soluble in water (e.g., 0.35-0.71 M) and has been detected at high concentrations in groundwater. The presence of MTBE in groundwater poses a potential health problem. The documented effects of MTBE exposure are headaches, vomiting, diarrhea, fever, cough, muscle aches, sleepiness, disorientation, dizziness, and skin and eye irritation. To address these problems, photocatalytic treatment is the preferred treatment for polluted water. In the present work, a simple and template-free solution phase synthesis method has been developed for the preparation of novel cadmium sulfide (CdS) hollow microspheres using cadmium nitrate and thioacetamide precursors. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction, high-resolution scanning electron microscopy (HR-SEM), X-ray photoelectron spectroscopy, and UV-visible diffused reflectance spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres, which evolved by the oriented aggregation of the primary CdS nanocrystals. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading MTBE in aqueous solution under visible light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light

  8. Characterization and modeling of SET/RESET cycling induced read-disturb failure time degradation in a resistive switching memory

    Science.gov (United States)

    Su, Po-Cheng; Hsu, Chun-Chi; Du, Sin-I.; Wang, Tahui

    2017-12-01

    Read operation induced disturbance in SET-state in a tungsten oxide resistive switching memory is investigated. We observe that the reduction of oxygen vacancy density during read-disturb follows power-law dependence on cumulative read-disturb time. Our study shows that the SET-state read-disturb immunity progressively degrades by orders of magnitude as SET/RESET cycle number increases. To explore the cause of the read-disturb degradation, we perform a constant voltage stress to emulate high-field stress effects in SET/RESET cycling. We find that the read-disturb failure time degradation is attributed to high-field stress-generated oxide traps. Since the stress-generated traps may substitute for some of oxygen vacancies in forming conductive percolation paths in a switching dielectric, a stressed cell has a reduced oxygen vacancy density in SET-state, which in turn results in a shorter read-disturb failure time. We develop an analytical read-disturb degradation model including both cycling induced oxide trap creation and read-disturb induced oxygen vacancy reduction. Our model can well reproduce the measured read-disturb failure time degradation in a cycled cell without using fitting parameters.

  9. Nicotine induces mitochondrial fission through mitofusin degradation in human multipotent embryonic carcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Naoya; Yamada, Shigeru [Division of Pharmacology, National Institute of Health Sciences (Japan); Asanagi, Miki [Division of Pharmacology, National Institute of Health Sciences (Japan); Faculty of Engineering, Department of Materials Science and Engineering, Yokohama National University (Japan); Sekino, Yuko [Division of Pharmacology, National Institute of Health Sciences (Japan); Kanda, Yasunari, E-mail: kanda@nihs.go.jp [Division of Pharmacology, National Institute of Health Sciences (Japan)

    2016-02-05

    Nicotine is considered to contribute to the health risks associated with cigarette smoking. Nicotine exerts its cellular functions by acting on nicotinic acetylcholine receptors (nAChRs), and adversely affects normal embryonic development. However, nicotine toxicity has not been elucidated in human embryonic stage. In the present study, we examined the cytotoxic effects of nicotine in human multipotent embryonal carcinoma cell line NT2/D1. We found that exposure to 10 μM nicotine decreased intracellular ATP levels and inhibited proliferation of NT2/D1 cells. Because nicotine suppressed energy production, which is a critical mitochondrial function, we further assessed the effects of nicotine on mitochondrial dynamics. Staining with MitoTracker revealed that 10 μM nicotine induced mitochondrial fragmentation. The levels of the mitochondrial fusion proteins, mitofusins 1 and 2, were also reduced in cells exposed to nicotine. These nicotine effects were blocked by treatment with mecamylamine, a nonselective nAChR antagonist. These data suggest that nicotine degrades mitofusin in NT2/D1 cells and thus induces mitochondrial dysfunction and cell growth inhibition in a nAChR-dependent manner. Thus, mitochondrial function in embryonic cells could be used to assess the developmental toxicity of chemicals.

  10. Tributyltin induces mitochondrial fission through NAD-IDH dependent mitofusin degradation in human embryonic carcinoma cells.

    Science.gov (United States)

    Yamada, Shigeru; Kotake, Yaichiro; Nakano, Mizuho; Sekino, Yuko; Kanda, Yasunari

    2015-08-01

    Organotin compounds, such as tributyltin (TBT), are well-known endocrine disruptors. TBT acts at the nanomolar level through genomic pathways via the peroxisome proliferator activated receptor (PPAR)/retinoid X receptor (RXR). We recently reported that TBT inhibits cell growth and the ATP content in the human embryonic carcinoma cell line NT2/D1 via a non-genomic pathway involving NAD(+)-dependent isocitrate dehydrogenase (NAD-IDH), which metabolizes isocitrate to α-ketoglutarate. However, the molecular mechanisms by which NAD-IDH mediates TBT toxicity remain unclear. In the present study, we evaluated the effects of TBT on mitochondrial NAD-IDH and energy production. Staining with MitoTracker revealed that nanomolar TBT levels induced mitochondrial fragmentation. TBT also degraded the mitochondrial fusion proteins, mitofusins 1 and 2. Interestingly, apigenin, an inhibitor of NAD-IDH, mimicked the effects of TBT. Incubation with an α-ketoglutarate analogue partially recovered TBT-induced mitochondrial dysfunction, supporting the involvement of NAD-IDH. Our data suggest that nanomolar TBT levels impair mitochondrial quality control via NAD-IDH in NT2/D1 cells. Thus, mitochondrial function in embryonic cells could be used to assess cytotoxicity associated with metal exposure.

  11. Nicotine induces mitochondrial fission through mitofusin degradation in human multipotent embryonic carcinoma cells

    International Nuclear Information System (INIS)

    Hirata, Naoya; Yamada, Shigeru; Asanagi, Miki; Sekino, Yuko; Kanda, Yasunari

    2016-01-01

    Nicotine is considered to contribute to the health risks associated with cigarette smoking. Nicotine exerts its cellular functions by acting on nicotinic acetylcholine receptors (nAChRs), and adversely affects normal embryonic development. However, nicotine toxicity has not been elucidated in human embryonic stage. In the present study, we examined the cytotoxic effects of nicotine in human multipotent embryonal carcinoma cell line NT2/D1. We found that exposure to 10 μM nicotine decreased intracellular ATP levels and inhibited proliferation of NT2/D1 cells. Because nicotine suppressed energy production, which is a critical mitochondrial function, we further assessed the effects of nicotine on mitochondrial dynamics. Staining with MitoTracker revealed that 10 μM nicotine induced mitochondrial fragmentation. The levels of the mitochondrial fusion proteins, mitofusins 1 and 2, were also reduced in cells exposed to nicotine. These nicotine effects were blocked by treatment with mecamylamine, a nonselective nAChR antagonist. These data suggest that nicotine degrades mitofusin in NT2/D1 cells and thus induces mitochondrial dysfunction and cell growth inhibition in a nAChR-dependent manner. Thus, mitochondrial function in embryonic cells could be used to assess the developmental toxicity of chemicals.

  12. Andrographolide induces degradation of mutant p53 via activation of Hsp70.

    Science.gov (United States)

    Sato, Hirofumi; Hiraki, Masatsugu; Namba, Takushi; Egawa, Noriyuki; Baba, Koichi; Tanaka, Tomokazu; Noshiro, Hirokazu

    2018-05-22

    The tumor suppressor gene p53 encodes a transcription factor that regulates various cellular functions, including DNA repair, apoptosis and cell cycle progression. Approximately half of all human cancers carry mutations in p53 that lead to loss of tumor suppressor function or gain of functions that promote the cancer phenotype. Thus, targeting mutant p53 as an anticancer therapy has attracted considerable attention. In the current study, a small-molecule screen identified andrographlide (ANDRO) as a mutant p53 suppressor. The effects of ANDRO, a small molecule isolated from the Chinese herb Andrographis paniculata, on tumor cells carrying wild-type or mutant p53 were examined. ANDRO suppressed expression of mutant p53, induced expression of the cyclin-dependent kinase inhibitor p21 and pro-apoptotic proteins genes, and inhibited the growth of cancer cells harboring mutant p53. ANDRO also induced expression of the heat-shock protein (Hsp70) and increased binding between Hsp70 and mutant p53 protein, thus promoting proteasomal degradation of p53. These results provide novel insights into the mechanisms regulating the function of mutant p53 and suggest that activation of Hsp70 may be a new strategy for the treatment of cancers harboring mutant p53.

  13. Degraded iota-carrageenan can induce apoptosis in human osteosarcoma cells via the Wnt/β-catenin signaling pathway.

    Science.gov (United States)

    Jin, Zhe; Han, Ya-Xin; Han, Xiao-Rui

    2013-01-01

    Osteosarcoma (OS) is a high-grade malignant bone tumor. Therefore, using both in vitro and in vivo assays, the effects of degraded iota-Carrageenan (ι-CGN) on a human osteosarcoma cell line, HOS, were examined. Degraded ι-CGN was observed to induce apoptosis and G(1) phase arrest in HOS cells. Moreover, degraded ι-CGN suppressed tumor growth in established xenograft tumor models. Accordingly, the survival rate of these mice was significantly higher than that of mice bearing tumors treated with native ι-CGN or PBS. In addition, the formation of intratumoral microvessels was inhibited following treatment with degraded ι-CGN. In Western blot assays, degraded ι-CGN was found to inhibit the Wnt/β-catenin signaling pathway. Overall, these studies demonstrate the antitumor activity of degraded ι-CGN toward the OS cell line, HOS. Moreover, valuable insight into the mechanisms mediated by degraded ι-CGN was obtained, potentially leading to the identification of novel treatments for OS. However, additional studies are needed to confirm these results in other cell types, particularly in human umbilical vein endothelial cells.

  14. Photocatalytic degradation of some organic dyes under solar light irradiation using TiO2 and ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Mojtaba Amini

    2016-01-01

    Full Text Available Nanoparticles of the ZnO and TiO2 were synthesized and the physicochemical properties of the compounds were characterized by IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The XRD patterns of the ZnO and TiO2 nanoparticles could be indexed to hexagonal and rutile phase, respectively. Aggregated nanoparticles of ZnO and TiO2 with spherical-like shapes were observed with particle diameter in the range of 80-100 nm. These nanoparticles were used for photocatalytic degradation of various dyes, Rhodamine B (RhB, Methylene blue (MB and Acridine orange (AO under solar light irradiation at room temperature. Effect of the amount of catalyst on the rate of photodegradation was investigated. In general, because ZnO is unstable, due to incongruous dissolution to yield Zn(OH2 on the ZnO particle surfaces and thus leading to catalyst inactivation,the catalytic activity of the system for photodegradation of dyes decreased dramatically when TiO2 was replaced by ZnO.

  15. Protonated graphitic carbon nitride coated metal-organic frameworks with enhanced visible-light photocatalytic activity for contaminants degradation

    Science.gov (United States)

    Huang, Jie; Zhang, Xibiao; Song, Haiyan; Chen, Chunxia; Han, Fuqin; Wen, Congcong

    2018-05-01

    Most of the reported composites of g-C3N4/metal-organic frameworks (MOFs) were obtained via exfoliation of g-C3N4 and wrapping the nanosheets on MOFs with weak interaction. In this work, chemical protonation of g-C3N4 and dip-coating was adopted as a feasible pathway to achieve the real combination of g-C3N4 derivatives with a familiar MOF material MIL-100(Fe). Structural, chemical and photophysical properties of the novel hybrid photocatalysts were characterized and compared to those of the parent materials. It was verified that the protonated g-C3N4 species of appropriate content were uniformly coated along the frameworks of MIL-100(Fe) with strong interaction. The optimal materials maintained the intact framework structure, surface property and porosity of MIL-100(Fe), as well as the inherent structural units and physicochemical properties of C3N4. In comparison to the parent materials, the protonated g-C3N4 coated MIL-100(Fe) materials exhibited enhanced photocatalytic activity in degradation of rhodamine B or methylene blue dye, as well as in oxidative denitrogenation for pyridine by molecular oxygen under visible light. Introduction of protonated g-C3N4 on MOFs improved the adsorption ability for contaminant molecules. Furthermore, coating effect provided a platform for rapid photoexcited electrons transfer and superior separation of photogenerated electron-hole pairs. Photocatalytic conversion of the three contaminants followed different mechanisms.

  16. Morphology Evolution and Degradation of CsPbBr3 Nanocrystals under Blue Light-Emitting Diode Illumination.

    Science.gov (United States)

    Huang, Shouqiang; Li, Zhichun; Wang, Bo; Zhu, Nanwen; Zhang, Congyang; Kong, Long; Zhang, Qi; Shan, Aidang; Li, Liang

    2017-03-01

    Under illumination of light-emitting diode (LED) or sunlight, the green color of all-inorganic CsPbBr 3 perovskite nanocrystals (CPB-NCs) often quickly changes to yellow, followed by large photoluminescence (PL) loss. To figure out what is happening on CPB-NCs during the color change process, the morphology, structure, and PL evolutions are systematically investigated by varying the influence factors of illumination, moisture, oxygen, and temperature. We find that the yellow color is mainly originated from the large CPB crystals formed in the illumination process. With maximized isolation of oxygen for the sandwiched film or the uncovered film stored in nitrogen, the color change can be dramatically slowed down whether there is water vapor or not. Under dark condition, the PL emissions are not significantly influenced by the varied relative humidity (RH) levels and temperatures up to 60 °C. Under the precondition of oxygen or air, color change and PL loss become more obvious when increasing the illumination power or RH level, and the large-sized cubic CPB crystals are further evolved into the oval-shaped crystals. We confirm that oxygen is the crucial factor to drive the color change, which has the strong synergistic effect with the illumination and moisture for the degradation of the CPB film. Meanwhile, the surface decomposition and the increased charge trap states occurred in the formed large CPB crystals play important roles for the PL loss.

  17. Human-Induced Vegetation Degradation in a Semi-Arid Rangeland

    Science.gov (United States)

    Jackson, Hasan

    Current assessments of anthropogenic land degradation and its impact on vegetation at regional scales are prone to large uncertainties due to the lack of an objective, transferable, spatially and temporally explicit measure of land degradation. These uncertainties have resulted in contradictory estimates of degradation extent and severity and the role of human activities. The uncertainties limit the ability to assess the effects on the biophysical environment and effectiveness of past, current, and future policies of land use. The overall objective of the dissertation is to assess degradation in a semi-arid region at a regional scale where the process of anthropogenic land degradation is evident. Net primary productivity (NPP) is used as the primary indicator to measure degradation. It is hypothesized that land degradation resulting from human factors on the landscape irreversibly reduces NPP below the potential set by environmental conditions. It is also hypothesized that resulting reductions in NPP are distinguishable from natural, spatial and temporal, variability in NPP. The specific goals of the dissertation are to (1) identify the extent and severity of degradation using productivity as the primary surrogate, (2) compare the degradation of productivity to other known mechanisms of degradation, and (3) relate the expression of degradation to components of vegetation and varying environmental conditions. This dissertation employed the Local NPP Scaling (LNS) approach to identify patterns of anthropogenic degradation of NPP in the Burdekin Dry Tropics (BDT) region of Queensland (14 million hectares), Australia from 2000 to 2013. The method started with land classification based on the environmental factors presumed to control NPP to group pixels having similar potential NPP. Then, satellite remotely sensing data were used to compare actual NPP with its potential. The difference, in units of mass of carbon fixed in NPP per unit area per monitoring interval and

  18. Light-Induced Acid Generation on a Gatekeeper for Smart Nitric Oxide Delivery.

    Science.gov (United States)

    Choi, Hyung Woo; Kim, Jihoon; Kim, Jinhwan; Kim, Yonghwi; Song, Hyun Beom; Kim, Jeong Hun; Kim, Kimoon; Kim, Won Jong

    2016-04-26

    We report herein the design of a light-responsive gatekeeper for smart nitric oxide (NO) delivery. The gatekeeper is composed of a pH-jump reagent as an intermediary of stimulus and a calcium phosphate (CaP) coating as a shielding layer for NO release. The light irradiation and subsequent acid generation are used as triggers for uncapping the gatekeeper and releasing NO. The acids generated from a light-activated pH-jump agent loaded in the mesoporous nanoparticles accelerated the degradation of the CaP-coating layers on the nanoparticles, facilitating the light-responsive NO release from diazeniumdiolate by exposing a NO donor to physiological conditions. Using the combination of the pH-jump reagent and CaP coating, we successfully developed a light-responsive gatekeeper system for spatiotemporal-controlled NO delivery.

  19. Ouabain-induced internalization and lysosomal degradation of the Na+/K+-ATPase.

    Science.gov (United States)

    Cherniavsky-Lev, Marina; Golani, Ofra; Karlish, Steven J D; Garty, Haim

    2014-01-10

    Internalization of the Na(+)/K(+)-ATPase (the Na(+) pump) has been studied in the human lung carcinoma cell line H1299 that expresses YFP-tagged α1 from its normal genomic localization. Both real-time imaging and surface biotinylation have demonstrated internalization of α1 induced by ≥100 nm ouabain which occurs in a time scale of hours. Unlike previous studies in other systems, the ouabain-induced internalization was insensitive to Src or PI3K inhibitors. Accumulation of α1 in the cells could be augmented by inhibition of lysosomal degradation but not by proteosomal inhibitors. In agreement, the internalized α1 could be colocalized with the lysosomal marker LAMP1 but not with Golgi or nuclear markers. In principle, internalization could be triggered by a conformational change of the ouabain-bound Na(+)/K(+)-ATPase molecule or more generally by the disruption of cation homeostasis (Na(+), K(+), Ca(2+)) due to the partial inhibition of active Na(+) and K(+) transport. Overexpression of ouabain-insensitive rat α1 failed to inhibit internalization of human α1 expressed in the same cells. In addition, incubating cells in a K(+)-free medium did not induce internalization of the pump or affect the response to ouabain. Thus, internalization is not the result of changes in the cellular cation balance but is likely to be triggered by a conformational change of the protein itself. In physiological conditions, internalization may serve to eliminate pumps that have been blocked by endogenous ouabain or other cardiac glycosides. This mechanism may be required due to the very slow dissociation of the ouabain·Na(+)/K(+)-ATPase complex.

  20. Ag3PO4/ZnO: An efficient visible-light-sensitized composite with its application in photocatalytic degradation of Rhodamine B

    International Nuclear Information System (INIS)

    Liu, Wei; Wang, Mingliang; Xu, Chunxiang; Chen, Shifu; Fu, Xianliang

    2013-01-01

    Graphical abstract: The free OH radicals generated in the VB of ZnO play the primary role in the visible-light photocatalytic degradation of RhB in Ag 3 PO 4 /ZnO system. The accumulated electrons in the CB of Ag 3 PO 4 can be transferred to O 2 adsorbed on the surface of the composite semiconductors and H 2 O 2 yields. H 2 O 2 reacts with electrons in succession to produce active ·OH to some extent. Display Omitted Highlights: ► Efficient visible-light-sensitized Ag 3 PO 4 /ZnO composites were successfully prepared. ► Effect of Ag 3 PO 4 content on the catalytic activity of Ag 3 PO 4 /ZnO is studied in detail. ► Rate constant of RhB degradation over Ag 3 PO 4 (3.0 wt.%)/ZnO is 3 times that of Ag 3 PO 4 . ► The active species in RhB degradation are examined by adding a series of scavengers. ► Visible light degradation mechanism of RhB over Ag 3 PO 4 /ZnO is systematically studied. -- Abstract: The efficient visible-light-sensitized Ag 3 PO 4 /ZnO composites with various weight percents of Ag 3 PO 4 were prepared by a facile ball milling method. The photocatalysts were characterized by XRD, DRS, SEM, EDS, XPS, and BET specific area. The ·OH radicals produced during the photocatalytic reaction was detected by the TA–PL technique. The photocatalytic property of Ag 3 PO 4 /ZnO was evaluated by photocatalytic degradation of Rhodamine B under visible light irradiation. Significantly, the results revealed that the photocatalytic activity of the composites was much higher than that of pure Ag 3 PO 4 and ZnO. The rate constant of RhB degradation over Ag 3 PO 4 (3.0 wt.%)/ZnO is 3 times that of single-phase Ag 3 PO 4 . The optimal percentage of Ag 3 PO 4 in the composite is 3.0 wt.%. It is proposed that the ·OH radicals produced in the valence band of ZnO play the leading role in the photocatalytic degradation of Rhodamine B by Ag 3 PO 4 /ZnO systems under visible light irradiation.

  1. Systematic analysis of FKBP inducible degradation domain tagging strategies for the human malaria parasite Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Mauro Ferreira de Azevedo

    Full Text Available Targeted regulation of protein levels is an important tool to gain insights into the role of proteins essential to cell function and development. In recent years, a method based on mutated forms of the human FKBP12 has been established and used to great effect in various cell types to explore protein function. The mutated FKBP protein, referred to as destabilization domain (DD tag when fused with a native protein at the N- or C-terminus targets the protein for proteosomal degradation. Regulated expression is achieved via addition of a compound, Shld-1, that stabilizes the protein and prevents degradation. A limited number of studies have used this system to provide powerful insight into protein function in the human malaria parasite Plasmodium falciparum. In order to better understand the DD inducible system in P. falciparum, we studied the effect of Shld-1 on parasite growth, demonstrating that although development is not impaired, it is delayed, requiring the appropriate controls for phenotype interpretation. We explored the quantified regulation of reporter Green Fluorescent Protein (GFP and luciferase constructs fused to three DD variants in parasite cells either via transient or stable transfection. The regulation obtained with the original FKBP derived DD domain was compared to two triple mutants DD24 and DD29, which had been described to provide better regulation for C-terminal tagging in other cell types. When cloned to the C-terminal of reporter proteins, DD24 provided the strongest regulation allowing reporter activity to be reduced to lower levels than DD and to restore the activity of stabilised proteins to higher levels than DD29. Importantly, DD24 has not previously been applied to regulate proteins in P. falciparum. The possibility of regulating an exported protein was addressed by targeting the Ring-Infected Erythrocyte Surface Antigen (RESA at its C-terminus. The tagged protein demonstrated an important modulation of its

  2. Histone deacetylase inhibitor, Trichostatin A induces ubiquitin-dependent cyclin D1 degradation in MCF-7 breast cancer cells

    Directory of Open Access Journals (Sweden)

    Charles Coombes R

    2006-02-01

    Full Text Available Abstract Background Cyclin D1 is an important regulator of G1-S phase cell cycle transition and has been shown to be important for breast cancer development. GSK3β phosphorylates cyclin D1 on Thr-286, resulting in enhanced ubiquitylation, nuclear export and degradation of the cyclin in the cytoplasm. Recent findings suggest that the development of small-molecule cyclin D1 ablative agents is of clinical relevance. We have previously shown that the histone deacetylase inhibitor trichostatin A (TSA induces the rapid ubiquitin-dependent degradation of cyclin D1 in MCF-7 breast cancer cells prior to repression of cyclin D1 gene (CCND1 transcription. TSA treatment also resulted in accumulation of polyubiquitylated GFP-cyclin D1 species and reduced levels of the recombinant protein within the nucleus. Results Here we provide further evidence for TSA-induced ubiquitin-dependent degradation of cyclin D1 and demonstrate that GSK3β-mediated nuclear export facilitates this activity. Our observations suggest that TSA treatment results in enhanced cyclin D1 degradation via the GSK3β/CRM1-dependent nuclear export/26S proteasomal degradation pathway in MCF-7 cells. Conclusion We have demonstrated that rapid TSA-induced cyclin D1 degradation in MCF-7 cells requires GSK3β-mediated Thr-286 phosphorylation and the ubiquitin-dependent 26S proteasome pathway. Drug induced cyclin D1 repression contributes to the inhibition of breast cancer cell proliferation and can sensitize cells to CDK and Akt inhibitors. In addition, anti-cyclin D1 therapy may be highly specific for treating human breast cancer. The development of potent and effective cyclin D1 ablative agents is therefore of clinical relevance. Our findings suggest that HDAC inhibitors may have therapeutic potential as small-molecule cyclin D1 ablative agents.

  3. Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

    DEFF Research Database (Denmark)

    Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

    2015-01-01

    An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, which are the two main environmental stress factors that promote potential-induced degradation (PID). This model was derived...

  4. Accelerated Testing and Modeling of Potential-Induced Degradation as a Function of Temperature and Relative Humidity

    DEFF Research Database (Denmark)

    Hacke, Peter; Spataru, Sergiu; Terwilliger, Kent

    2015-01-01

    An acceleration model based on the Peck equation was applied to power performance of crystalline silicon cell modules as a function of time and of temperature and humidity, the two main environmental stress factors that promote potential-induced degradation. This model was derived from module pow...

  5. Solar light-induced production of reactive oxygen species by single walled carbon nanotubes in water

    Science.gov (United States)

    Photosensitizing processes of engineered nanomaterials (ENMs) which include photo-induced production of reactive oxygen species (ROS) convert light energy into oxidizing chemical energy that mediates transformations of nanomaterials. The oxidative stress associated with ROS may p...

  6. Light meson decays from photon-induced reactions with CLAS

    Energy Technology Data Exchange (ETDEWEB)

    Kunkel, Michael C. [Forschungszentrum Juelich (Germany); Collaboration: CLAS-Collaboration

    2015-07-01

    Photo-production experiments with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Laboratory produce data sets with unprecedented statistics of light mesons. With these data sets, measurements of transition form factors for η, ω, and η' via conversion decays are performed using a line shape analysis on the invariant mass of the final state dileptons. Tests of fundamental symmetries and information on the light quark mass difference are performed using a Dalitz plot analysis of the meson decay. In addition, the data allows for a search for dark matter, such as the heavy photon via conversion decays of light mesons and physics beyond the Standard Model is searched for via invisible decays of η mesons. An overview of the first results and future prospects is given.

  7. The Use of Radiation-Induced Degradation in Controlling Molecular Weights of Polysaccharides : The Effect of Humidity

    International Nuclear Information System (INIS)

    Sen, M.

    2006-01-01

    Better understanding of chemistry of radiation-induced degradation is becoming of increasing importance on account of the utilization of polymeric materials in a variety of radiation environments as well as beneficial uses of degraded polymers. It is very well known that polysaccharides in dry form or in solution degrade when exposed to ionizing radiation. In this study degrading effect of radiation has been considered from the point of view of controlling the molecular weights of kappa- and iota-carrageenans and sodium alginate irradiated under varying environmental conditions. The humidity equilibrated polymer samples kept over saturated aqueous salt solutions of NaCl, NaNO 3 and MgCl 2 were irradiated in a Gammacell 220 at room temperature. The degradation was investigated in detail by a careful Gel Permeation Chromatographic analysis of their respective molecular weights before and after irradiation Alexander-Charlesby-Ross equation was used in determining their radiation-chemical yields. Degradation yield is the highest for dry irradiated kappa- (G(S) = 0.73) and iota-carrageenans (G(S) = 2.43) and with small amount of water taken up from surrounding humidity degradation becomes less pronounced and G(S) values show a decrease down to G(S) = 0.16 and 0.87 at 75 % relative humidity, respectively. At very high water contents degradation effect again becomes more effective. Sodium alginate has fount to be less sensitive to the effect of humidity. When there is small amount of water in the polysaccharide structure, it is unlikely to expect an indirect effect of radiation. The water located in between the polymer chains however can give enough mobility to kappa and iota karrageenans chains, plastifying effect, which may enhance the radical-radical combinations thus lowering the rate of degradation hence reducing G(S) values

  8. Use of Activated Carbon in Packaging to Attenuate Formaldehyde-Induced and Formic Acid-Induced Degradation and Reduce Gelatin Cross-Linking in Solid Dosage Forms.

    Science.gov (United States)

    Colgan, Stephen T; Zelesky, Todd C; Chen, Raymond; Likar, Michael D; MacDonald, Bruce C; Hawkins, Joel M; Carroll, Sophia C; Johnson, Gail M; Space, J Sean; Jensen, James F; DeMatteo, Vincent A

    2016-07-01

    Formaldehyde and formic acid are reactive impurities found in commonly used excipients and can be responsible for limiting drug product shelf-life. Described here is the use of activated carbon in drug product packaging to attenuate formaldehyde-induced and formic acid-induced drug degradation in tablets and cross-linking in hard gelatin capsules. Several pharmaceutical products with known or potential vulnerabilities to formaldehyde-induced or formic acid-induced degradation or gelatin cross-linking were subjected to accelerated stability challenges in the presence and absence of activated carbon. The effects of time and storage conditions were determined. For all of the products studied, activated carbon attenuated drug degradation or gelatin cross-linking. This novel use of activated carbon in pharmaceutical packaging may be useful for enhancing the chemical stability of drug products or the dissolution stability of gelatin-containing dosage forms and may allow for the 1) extension of a drug product's shelf-life when the limiting attribute is a degradation product induced by a reactive impurity, 2) marketing of a drug product in hotter and more humid climatic zones than currently supported without the use of activated carbon, and 3) enhanced dissolution stability of products that are vulnerable to gelatin cross-linking. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  9. l-Serine Enhances Light-Induced Circadian Phase Resetting in Mice and Humans.

    Science.gov (United States)

    Yasuo, Shinobu; Iwamoto, Ayaka; Lee, Sang-Il; Ochiai, Shotaro; Hitachi, Rina; Shibata, Satomi; Uotsu, Nobuo; Tarumizu, Chie; Matsuoka, Sayuri; Furuse, Mitsuhiro; Higuchi, Shigekazu

    2017-12-01

    Background: The circadian clock is modulated by the timing of ingestion or food composition, but the effects of specific nutrients are poorly understood. Objective: We aimed to identify the amino acids that modulate the circadian clock and reset the light-induced circadian phase in mice and humans. Methods: Male CBA/N mice were orally administered 1 of 20 l-amino acids, and the circadian and light-induced phase shifts of wheel-running activity were analyzed. Antagonists of several neurotransmitter pathways were injected before l-serine administration, and light-induced phase shifts were analyzed. In addition, the effect of l-serine on the light-induced phase advance was investigated in healthy male students (mean ± SD age 22.2 ± 1.8 y) by using dim-light melatonin onset (DLMO) determined by saliva samples as an index of the circadian phase. Results: l-Serine administration enhanced light-induced phase shifts in mice (1.86-fold; P light-dark cycle by 6 h, l-serine administration slightly accelerated re-entrainment to the shifted cycle. In humans, l-serine ingestion before bedtime induced significantly larger phase advances of DLMO after bright-light exposure during the morning (means ± SEMs-l-serine: 25.9 ± 6.6 min; placebo: 12.1 ± 7.0 min; P light-induced phase resetting in mice and humans, and it may be useful for treating circadian disturbances. © 2017 American Society for Nutrition.

  10. Light induced electron transfer reactions of metal complexes

    International Nuclear Information System (INIS)

    Sutin, N.; Creutz, C.

    1980-01-01

    Properties of the excited states of tris(2,2'-bipyridine) and tris(1,10-phenanthroline) complexes of chromium(III), iron(II), ruthenium(II), osmium(II), rhodium(III), and iridium(III) are described. The electron transfer reactions of the ground and excited states are discussed and interpreted in terms of the driving force for the reaction and the distortions of the excited states relative to the corresponding ground states. General considerations relevant to the conversion of light into chemical energy are presented and progress in the use of polypyridine complexes to effect the light decomposition of water into hydrogen and oxygen is reviewed

  11. Lighting

    Data.gov (United States)

    Federal Laboratory Consortium — Lighting Systems Test Facilities aid research that improves the energy efficiency of lighting systems. • Gonio-Photometer: Measures illuminance from each portion of...

  12. MoS{sub 2}–GO nanocomposites synthesized via a hydrothermal hydrogel method for solar light photocatalytic degradation of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yong; Zhou, Yifeng, E-mail: yifengzhou@126.com; Nie, Wangyan; Chen, Pengpeng, E-mail: chenpp@ahu.edu.cn

    2015-12-01

    Graphical abstract: - Highlights: • The molybdenum disulfide–graphene oxide (MoS{sub 2}–GO) nanocomposite was synthesized via a one-step hydrothermal hydrogel method. • MoS{sub 2} and GO were composited fairly well in the obtained nanocomposites. • The electrons–hole pair recombination rate of MoS{sub 2} was greatly reduced via compositing with graphene. • The MoS{sub 2}–GO nanocomposite exhibited excellent photocatalytic performance for the degradation of methylene blue under solar light irradiation. - Abstract: In this work, molybdenum disulfide–graphene oxide (MoS{sub 2}–GO) composite hydrogel was prepared via a one-step hydrothermal method. The morphology and structure of the as-prepared hydrogels with different proportions of MoS{sub 2} and GO were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, electrochemical impedance spectra and UV–vis absorption spectroscopy. The photocatalytic performance of MoS{sub 2}–GO nanocomposites was studied toward the degradation of methylene blue (MB). Results showed that the MoS{sub 2}–GO nanocomposites exhibited improved photocatalytic activities in the degradation of MB with a maximum degradation rate of 99% under solar lights irradiation within 60 min. The synthesized MoS{sub 2}–GO composite hydrogel possesses great potential toward the development of newly synthesizable catalysts in the field of organic degradation in water.

  13. Degradation of atenolol via heterogeneous activation of persulfate by using BiOCl@Fe3O4 catalyst under simulated solar light irradiation.

    Science.gov (United States)

    Shi, Yahong; Chen, Hongche; Wu, Yanlin; Dong, Wenbo

    2018-01-01

    Efficient oxidative degradation of pharmaceutical pollutants in aquatic environments is of great importance. This study used magnetic BiOCl@Fe 3 O 4 catalyst to activate persulfate (PS) under simulated solar light irradiation. This degradation system was evaluated using atenolol (ATL) as target pollutant. Four reactive species were identified in the sunlight/BiOCl@Fe 3 O 4 /PS system. The decreasing order of the contribution of each reactive species on ATL degradation was as follows: h +  ≈ HO ·  > O 2 ·-  > SO 4 ·- . pH significantly influenced ATL degradation, and an acidic condition favored the reaction. High degradation efficiencies were obtained at pH 2.3-5.5. ATL degradation rate increased with increased catalyst and PS contents. Moreover, ATL mineralization was higher in the sunlight/BiOCl@Fe 3 O 4 /PS system than in the sunlight/BiOCl@Fe 3 O 4 or sunlight/PS system. Nine possible intermediate products were identified through LC-MS analysis, and a degradation pathway for ATL was proposed. The BiOCl@Fe 3 O 4 nanomagnetic composite catalyst was synthesized in this work. This catalyst was easily separated and recovered from a treated solution by using a magnet, and it demonstrated a high catalytic activity. Increased amount of the BiOCl@Fe 3 O 4 catalyst obviously accelerated the efficiency of ATL degradation, and the reusability of the catalyst allowed the addition of a large dosage of BiOCl@Fe 3 O 4 to improve the degradation efficiency.

  14. Preparation of Hierarchical BiOBr Microspheres for Visible Light-Induced Photocatalytic Detoxification and Disinfection

    Directory of Open Access Journals (Sweden)

    Ayla Ahmad

    2016-01-01

    Full Text Available Photocatalytic degradation is a promising alternative to traditional wastewater treatment methods. Recently developed visible light-responsive photocatalyst, BiOBr, has attracted extensive attentions. Hereby, a detailed investigation of application of BiOBr to bacterial inactivation and organic pollutants degradation is reported. Hydrothermal catalyst was prepared using template-free method. While, for solvothermal synthesis, CTAB was used as a template. Results indicate a higher photocatalytic activity by the solvothermally prepared catalyst. Solvothermally prepared BiOBr exhibited high photocatalytic activities in both water detoxification and disinfection.

  15. Measurable difference in Cherenkov light between gamma and hadron induced EAS

    Energy Technology Data Exchange (ETDEWEB)

    Cabot, H.; Meynadier, Ch. [Universite de Perpignan, Groupe de Physique Fondamentale, Perpignan (France); Sobczynska, D. [Experimental Physics Department, University of Lodz, Lodz (Poland); Szabelska, B. [Soltan Institute for Nuclear Studies, Lodz (Poland); Szabelski, J. [Universite de Perpignan, Groupe de Physique Fondamentale, Perpignan (France)]|[Soltan Institute for Nuclear Studies, Lodz (Poland); Wibig, T. [Experimental Physics Department, University of Lodz, Lodz (Poland)

    1997-12-31

    We describe the possibly measurable difference in the Cherenkov light component of EAS induced by en electromagnetic particle (i.e. e{sup +}, e{sup -} or {gamma}) and induced by a hadron (i.e. proton or heavier nuclei) in TeV range. The method can be applied in experiments which use wavefront sampling method of EAS Cherenkov light detection (e.g. THEMISTOCLE, ASGAT). (author) 16 refs, 9 figs

  16. Rapid and efficient visible light photocatalytic dye degradation using AFe2O4 (A = Ba, Ca and Sr) complex oxides

    International Nuclear Information System (INIS)

    Vijayaraghavan, T.; Suriyaraj, S.P.; Selvakumar, R.; Venkateswaran, R.; Ashok, Anuradha

    2016-01-01

    Highlights: • Alkaline earth ferrites AFe 2 O 4 (A = Ba, Ca and Sr) were synthesized by sol–gel method. • Visible light photocatalytic activity of these ferrites were studied using congo red dye degradation. • BaFe 2 O 4 exhibited the best photocatalytic activity under visible light (xenon lamp) irradiation; CaFe 2 O 4 was the best photocatalyst under natural sun light irradiation. - Abstract: Photocatalytic activity of spinel type complex oxides has been investigated in this study. Alkaline earth ferrites AFe 2 O 4 (A = Ba, Ca, Sr) were synthesized by sol–gel method. Structural characterizations reveal that the synthesized ferrites have orthorhombic crystal structures with different space groups and cell dimensions when they have different alkaline earth metals in their A site. All the synthesized ferrites exhibited their bandgap in the range 2.14–2.19 eV. Their photocatalytic activities were studied using congo red dye under sunlight and xenon lamp radiation. The substitution of Ba, Ca and Sr at A site of these ferrites had varying impact on dye degradation process. Under xenon lamp irradiation, BaFe 2 O 4 exhibited the highest percentage of dye degradation (92% after 75 min). However, CaFe 2 O 4 showed the fastest degradation of the dye (70% within 15 min). In the absence of irradiation, SrFe 2 O 4 showed the highest dye adsorption (44% after 75 min).

  17. Ultraviolet light induced refractive index structures in germanosilica

    DEFF Research Database (Denmark)

    Svalgaard, Mikael

    1997-01-01

    The focus of the research presented in this ph.d. thesis is refractive index structures photoinduced in germanonsilica waveguides with ultra-violet (UV) radiation. The physical mechanisms involved in photosensitivity and applications of a wide range of UV induced refractive index structures in both...... application of a scanning near-field optical microscope to obtain high resolution images of UV induced refractive index structures and by monitoring the dynamics of UV induced index changes and luminescence. During part of my ph.d. project I have worked at the National Institute of Standards and Technolgy...

  18. High resolution Cerenkov light imaging of induced positron distribution in proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Fujii, Kento; Morishita, Yuki; Okumura, Satoshi; Komori, Masataka [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673 (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Aichi 462-8508 (Japan)

    2014-11-01

    Purpose: In proton therapy, imaging of the positron distribution produced by fragmentation during or soon after proton irradiation is a useful method to monitor the proton range. Although positron emission tomography (PET) is typically used for this imaging, its spatial resolution is limited. Cerenkov light imaging is a new molecular imaging technology that detects the visible photons that are produced from high-speed electrons using a high sensitivity optical camera. Because its inherent spatial resolution is much higher than PET, the authors can measure more precise information of the proton-induced positron distribution with Cerenkov light imaging technology. For this purpose, they conducted Cerenkov light imaging of induced positron distribution in proton therapy. Methods: First, the authors evaluated the spatial resolution of our Cerenkov light imaging system with a {sup 22}Na point source for the actual imaging setup. Then the transparent acrylic phantoms (100 × 100 × 100 mm{sup 3}) were irradiated with two different proton energies using a spot scanning proton therapy system. Cerenkov light imaging of each phantom was conducted using a high sensitivity electron multiplied charge coupled device (EM-CCD) camera. Results: The Cerenkov light’s spatial resolution for the setup was 0.76 ± 0.6 mm FWHM. They obtained high resolution Cerenkov light images of the positron distributions in the phantoms for two different proton energies and made fused images of the reference images and the Cerenkov light images. The depths of the positron distribution in the phantoms from the Cerenkov light images were almost identical to the simulation results. The decay curves derived from the region-of-interests (ROIs) set on the Cerenkov light images revealed that Cerenkov light images can be used for estimating the half-life of the radionuclide components of positrons. Conclusions: High resolution Cerenkov light imaging of proton-induced positron distribution was possible. The

  19. High resolution Cerenkov light imaging of induced positron distribution in proton therapy

    International Nuclear Information System (INIS)

    Yamamoto, Seiichi; Fujii, Kento; Morishita, Yuki; Okumura, Satoshi; Komori, Masataka; Toshito, Toshiyuki

    2014-01-01

    Purpose: In proton therapy, imaging of the positron distribution produced by fragmentation during or soon after proton irradiation is a useful method to monitor the proton range. Although positron emission tomography (PET) is typically used for this imaging, its spatial resolution is limited. Cerenkov light imaging is a new molecular imaging technology that detects the visible photons that are produced from high-speed electrons using a high sensitivity optical camera. Because its inherent spatial resolution is much higher than PET, the authors can measure more precise information of the proton-induced positron distribution with Cerenkov light imaging technology. For this purpose, they conducted Cerenkov light imaging of induced positron distribution in proton therapy. Methods: First, the authors evaluated the spatial resolution of our Cerenkov light imaging system with a 22 Na point source for the actual imaging setup. Then the transparent acrylic phantoms (100 × 100 × 100 mm 3 ) were irradiated with two different proton energies using a spot scanning proton therapy system. Cerenkov light imaging of each phantom was conducted using a high sensitivity electron multiplied charge coupled device (EM-CCD) camera. Results: The Cerenkov light’s spatial resolution for the setup was 0.76 ± 0.6 mm FWHM. They obtained high resolution Cerenkov light images of the positron distributions in the phantoms for two different proton energies and made fused images of the reference images and the Cerenkov light images. The depths of the positron distribution in the phantoms from the Cerenkov light images were almost identical to the simulation results. The decay curves derived from the region-of-interests (ROIs) set on the Cerenkov light images revealed that Cerenkov light images can be used for estimating the half-life of the radionuclide components of positrons. Conclusions: High resolution Cerenkov light imaging of proton-induced positron distribution was possible. The authors

  20. Giardia duodenalis Surface Cysteine Proteases Induce Cleavage of the Intestinal Epithelial Cytoskeletal Protein Villin via Myosin Light Chain Kinase.

    Directory of Open Access Journals (Sweden)

    Amol Bhargava

    Full Text Available Giardia duodenalis infections are among the most common causes of waterborne diarrhoeal disease worldwide. At the height of infection, G. duodenalis trophozoites induce multiple pathophysiological processes within intestinal epithelial cells that contribute to the development of diarrhoeal disease. To date, our understanding of pathophysiological processes in giardiasis remains incompletely understood. The present study reveals a previously unappreciated role for G. duodenalis cathepsin cysteine proteases in intestinal epithelial pathophysiological processes that occur during giardiasis. Experiments first established that Giardia trophozoites indeed produce cathepsin B and L in strain-dependent fashion. Co-incubation of G. duodenalis with human enterocytes enhanced cathepsin production by Assemblage A (NF and S2 isolates trophozoites, but not when epithelial cells were exposed to Assemblage B (GSM isolate trophozoites. Direct contact between G. duodenalis parasites and human intestinal epithelial monolayers resulted in the degradation and redistribution of the intestinal epithelial cytoskeletal protein villin; these effects were abolished when parasite cathepsin cysteine proteases were inhibited. Interestingly, inhibition of parasite proteases did not prevent degradation of the intestinal tight junction-associated protein zonula occludens 1 (ZO-1, suggesting that G. duodenalis induces multiple pathophysiological processes within intestinal epithelial cells. Finally, this study demonstrates that G. duodenalis-mediated disruption of villin is, at least, in part dependent on activation of myosin light chain kinase (MLCK. Taken together, this study indicates a novel role for parasite cathepsin cysteine proteases in the pathophysiology of G. duodenalis infections.

  1. Small-Molecule Sigma1 Modulator Induces Autophagic Degradation of PD-L1.

    Science.gov (United States)

    Maher, Christina M; Thomas, Jeffrey D; Haas, Derick A; Longen, Charles G; Oyer, Halley M; Tong, Jane Y; Kim, Felix J

    2018-02-01

    Emerging evidence suggests that Sigma1 ( SIGMAR1 , also known as sigma-1 receptor) is a unique ligand-regulated integral membrane scaffolding protein that contributes to cellular protein and lipid homeostasis. Previously, we demonstrated that some small-molecule modulators of Sigma1 alter endoplasmic reticulum (ER)-associated protein homeostasis pathways in cancer cells, including the unfolded protein response and autophagy. Programmed death-ligand 1 (PD-L1) is a type I integral membrane glycoprotein that is cotranslationally inserted into the ER and is processed and transported through the secretory pathway. Once at the surface of cancer cells, PD-L1 acts as a T-cell inhibitory checkpoint molecule and suppresses antitumor immunity. Here, we demonstrate that in Sigma1-expressing triple-negative breast and androgen-independent prostate cancer cells, PD-L1 protein levels were suppressed by RNAi knockdown of Sigma1 and by small-molecule inhibition of Sigma1. Sigma1-mediated action was confirmed by pharmacologic competition between Sigma1-selective inhibitor and activator ligands. When administered alone, the Sigma1 inhibitor decreased cell surface PD-L1 expression and suppressed functional interaction of PD-1 and PD-L1 in a coculture of T cells and cancer cells. Conversely, the Sigma1 activator increased PD-L1 cell surface expression, demonstrating the ability to positively and negatively modulate Sigma1 associated PD-L1 processing. We discovered that the Sigma1 inhibitor induced degradation of PD-L1 via autophagy, by a mechanism distinct from bulk macroautophagy or general ER stress-associated autophagy. Finally, the Sigma1 inhibitor suppressed IFNγ-induced PD-L1. Our data demonstrate that small-molecule Sigma1 modulators can be used to regulate PD-L1 in cancer cells and trigger its degradation by selective autophagy. Implications: Sigma1 modulators sequester and eliminate PD-L1 by autophagy, thus preventing functional PD-L1 expression at the cell surface. This

  2. Visible lights induced polymerization reactions: interactions between rose bengal and iron aren complex

    International Nuclear Information System (INIS)

    Burget, D.; Grotzinger, C.; Jacques, P.; Fouassier, J.P.

    1999-01-01

    The present paper is devoted to an investigation of the interactions between Rose Bengal (RB) and an Iron aren (Irg(+)) complex that are usable in visible light induced polymerization reactions. Steady state and flash photolysis experiments were performed in order to elucidate the nature of the intermediates formed after light excitation. A complete scheme of evolution of the excited states is discussed

  3. Light induced expression of β-glucosidase in Escherichia coli with autolysis of cell.

    Science.gov (United States)

    Chang, Fei; Zhang, Xianbing; Pan, Yu; Lu, Youxue; Fang, Wei; Fang, Zemin; Xiao, Yazhong

    2017-11-07

    β-Glucosidase has attracted substantial attention in the scientific community because of its pivotal role in cellulose degradation, glycoside transformation and many other industrial processes. However, the tedious and costly expression and purification procedures have severely thwarted the industrial applications of β-glucosidase. Thus development of new strategies to express β-glucosidases with cost-effective and simple procedure to meet the increasing demands on enzymes for biocatalysis is of paramount importance. Light activated cassette YF1/FixJ and the SRRz lysis system were successfully constructed to produce Bgl1A(A24S/F297Y), a mutant β-glucosidase tolerant to both glucose and ethanol. By optimizing the parameters for light induction, Bgl1A(A24S/F297Y) activity reached 33.22 ± 2.0 U/mL and 249.92 ± 12.25 U/mL in 250-mL flask and 3-L fermentation tank, respectively, comparable to the controls of 34.02 ± 1.96 U/mL and 322.21 ± 10.16 U/mL under similar culture conditions with IPTG induction. To further simplify the production of our target protein, the SRRz lysis gene cassette from bacteriophage Lambda was introduced to trigger cell autolysis. As high as 84.53 ± 6.79% and 77.21 ± 4.79% of the total β-glucosidase were released into the lysate after cell autolysis in 250 mL flasks and 3-L scale fermentation with lactose as inducer of SRRz. In order to reduce the cost of protein purification, a cellulose-binding module (CBM) from Clostridium thermocellum was fused into the C-terminal of Bgl1A(A24S/F297Y) and cellulose was used as an economic material to adsorb the fusion enzyme from the lysate. The yield of the fusion protein could reach 92.20 ± 2.27% after one-hour adsorption at 25 °C. We have developed an efficient and inexpensive way to produce β-glucosidase for potential industrial applications by using the combination of light induction, cell autolysis, and CBM purification strategy.

  4. TiO2 supported over porous silica photocatalysts for pesticide degradation using solar light: Part 2. Silica prepared using acrylic acid emulsion

    International Nuclear Information System (INIS)

    Phanikrishna Sharma, Mangalampalli V.; Durga Kumari, Valluri; Subrahmanyam, Machiraju

    2010-01-01

    An acrylic acid emulsion mixture is used for synthesis of novel porous silica (E-Si) material. The photocatalytic activity of TiO 2 under solar light irradiation for isoproturon (herbicide) degradation is drastically increased when dispersed over E-Si support using solid state dispersion (SSD) technique. The composite material is characterized by XRD, nitrogen adsorption-desorption isotherms, UV-vis DRS, SEM and TEM measurements. The photocatalytic activities of the composite catalysts are evaluated for different parameters. The 5 wt% TiO 2 /E-Si is found to be highly active for isoproturon degradation.

  5. TiO{sub 2} supported over porous silica photocatalysts for pesticide degradation using solar light: Part 2. Silica prepared using acrylic acid emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Phanikrishna Sharma, Mangalampalli V.; Durga Kumari, Valluri [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500607, Andhra Pradesh (India); Subrahmanyam, Machiraju, E-mail: subrahmanyam@iict.res.in [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500607, Andhra Pradesh (India)

    2010-03-15

    An acrylic acid emulsion mixture is used for synthesis of novel porous silica (E-Si) material. The photocatalytic activity of TiO{sub 2} under solar light irradiation for isoproturon (herbicide) degradation is drastically increased when dispersed over E-Si support using solid state dispersion (SSD) technique. The composite material is characterized by XRD, nitrogen adsorption-desorption isotherms, UV-vis DRS, SEM and TEM measurements. The photocatalytic activities of the composite catalysts are evaluated for different parameters. The 5 wt% TiO{sub 2}/E-Si is found to be highly active for isoproturon degradation.

  6. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Longxing, E-mail: hulxhhhb@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Deng, Guihua [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Lu, Wencong [College of Sciences, Shanghai University, Shanghai 200444 (China); Pang, Siwei; Hu, Xing [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China)

    2017-07-15

    Graphical abstract: The CdS/MIL-53(Fe) photocatalyst has been synthesized by a facile two-step solvothermal method and applied for photocatalytic degradation of organic pollutant RhB under visible light irradiation. - Highlights: • A novel CdS/MIL-53(Fe) photocatalyst was successfully synthesized via a facile two-step solvothermal method. • CdS/MIL-53(Fe) exhibited an enhanced visible-light photocatalytic degradation of RhB in water. • The mechanisms for the formation of CdS/MIL-53(Fe) and photocatalytic degradation of RhB were proposed. - Abstract: A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV–vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhB{sub aq}-visible light system was O{sub 2}{sup −}·; nevertheless, h{sup +} and ·OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs

  7. Synthesis and characterization of Fullerene modified ZnAlTi-LDO in photo-degradation of Bisphenol A under simulated visible light irradiation

    International Nuclear Information System (INIS)

    Ju, Liting; Wu, Pingxiao; Lai, Xiaolin; Yang, Shanshan; Gong, Beini; Chen, Meiqing

    2017-01-01

    In this study, ZnAlTi layered double hydroxide (ZnAlTi-LDH) combined with fullerene (C 60 ) was fabricated by the urea method, and calcined under vacuum atmosphere to obtain nanocomposites of C 60 -modified ZnAlTi layered double oxide (ZnAlTi-LDO). The morphology, structure and composition of the nanocomposites were analyzed by Scanning Electron Microscopy, High-resolution transmission electron microscopy, X-ray diffraction patterns, Fourier transform infrared and specific surface area. The UV-vis diffuse reflectance spectra indicated that the incorporation of C 60 expanded the absorption of ZnAlTi-LDO to visible-light region. The photo-degradation experiment was conducted by using a series of C 60 modified ZnAlTi-LDO with different C 60 weight percentage to degrade Bisphenol A (BPA) under simulated visible light irradiation. In this experiment, the degradation rate of C 60 modified ZnAlTi-LDO in photo-degradation of BPA under simulated visible light irradiation was over 80%. The intermediates formed in the degradation of BPA process by using LDO/C 60 -5% were 4-hydroxyphenyl-2-propanol, 4-isopropenylphenol and Phenol. Photogenerated holes, superoxide radical species, ·OH and singlet oxygen were considered to be responsible for the photodegradation process, among which superoxide radical species and ·OH played a predominant role in the photocatalytic reaction system. C 60 modified ZnAlTi-LDO catalysts for photocatalytic reduction shows great potential in degradation of organic pollutants and environmental remediation. - Highlights: • C 60 modified ZnAlTi-LDO enhance the photocatalytic reduction of BPA. • C 60 modified ZnAlTi-LDO was an efficient photocatalytic in the degradation of BPA under visible light. • Superoxide radical species played a predominant role in the photocatalytic reaction system. • C 60 expanded the absorption of ZnAlTi-LDO to visible-light region with the increasing content of C 60 .

  8. Deposition of CdS nanoparticles on MIL-53(Fe) metal-organic framework with enhanced photocatalytic degradation of RhB under visible light irradiation

    International Nuclear Information System (INIS)

    Hu, Longxing; Deng, Guihua; Lu, Wencong; Pang, Siwei; Hu, Xing

    2017-01-01

    Graphical abstract: The CdS/MIL-53(Fe) photocatalyst has been synthesized by a facile two-step solvothermal method and applied for photocatalytic degradation of organic pollutant RhB under visible light irradiation. - Highlights: • A novel CdS/MIL-53(Fe) photocatalyst was successfully synthesized via a facile two-step solvothermal method. • CdS/MIL-53(Fe) exhibited an enhanced visible-light photocatalytic degradation of RhB in water. • The mechanisms for the formation of CdS/MIL-53(Fe) and photocatalytic degradation of RhB were proposed. - Abstract: A novel composite, CdS/MIL-53(Fe), was successfully fabricated via a facile solvothermal method and characterized with XRD, SEM, TEM, XPS, FT-IR and UV–vis DRS. The results showed that the fabrication was able to result in a good dispersion of CdS nanoparticles onto MIL-53(Fe). The photocatalytic activities of the as-synthesized composite were investigated through the degradation of Rhodamine B (RhB) in water under visible light irradiation. It was found that the composite prepared at the mass ratio of CdS to MIL-53(Fe) of 1.5:1 displayed the highest photocatalytic activity. An approximately 92.5% of photocatalytic degradation of RhB was achieved at 0.5 g/L of 1.5-CdS/MIL dosage, 10 mg/L of initial RhB concentration and 23 °C of reaction temperature under visible light irradiation. The RhB photocatalytic degradation followed well the first-order kinetics equation and the increased catalyst dosage and optimal initial RhB concentration were responsible for the enhanced photocatalytic degradation. Quenching tests revealed that the predominant free radicals in the CdS/MIL-(53)-RhB aq -visible light system was O 2 − ·; nevertheless, h + and ·OH also contributed to a certain degree. The enhanced photocatalytic performance was ascribed to the formation of heterojunction structure between CdS and MIL-53(Fe) which significantly suppressed the recombination of photogenerated electron-hole pairs. Moreover, the

  9. Efficient photocatalytic degradation of ibuprofen in aqueous solution using novel visible-light responsive graphene quantum dot/AgVO{sub 3} nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Zhen-dong [Department of Physics, Tsinghua University, Beijing 100084 (China); Wang, Jia-jun [Shanghai Institute of Applied Radiation, Shanghai University, Shanghai 200444 (China); Wang, Liang, E-mail: wangl@shu.edu.cn [Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 200444 (China); Yang, Xiong-yu; Xu, Gang [Shanghai Institute of Applied Radiation, Shanghai University, Shanghai 200444 (China); Tang, Liang, E-mail: tang1liang@shu.edu.cn [Shanghai Institute of Applied Radiation, Shanghai University, Shanghai 200444 (China)

    2016-07-15

    Highlights: • A novel heterojunction photocatalyst, GQD/AgVO{sub 3} was prepared. • The morphology of GQD/AgVO{sub 3} was well characterized. • Ibuprofen was easily decomposed using GQD/AgVO{sub 3} under visible-light irradiation. • The degradation pathway of ibuprofen was also suggested. - Abstract: Single crystalline, non-toxicity, and long-term stability graphene quantum dots (GQDs) were modified onto the AgVO{sub 3} nanoribbons by a facile hydrothermal and sintering technique which constructs a unique heterojunction photocatalyst. Characterization results indicate that GQDs are well dispersed on the surface of AgVO{sub 3} nanoribbons and GQD/AgVO{sub 3} heterojunctions are formed, which can greatly promote the separation efficiency of photogenerated electron-hole pairs under visible light irradiation. By taking advantage of this feature, the GQD/AgVO{sub 3} heterojunctions exhibit considerable improvement on the photocatalytic activities for the degradation of ibuprofen (IBP) under visible light irradiation as compared to pure AgVO{sub 3}. The photocatalytic activity of GQD/AgVO{sub 3} heterojunctions is relevant with GQD ratio and the optimal activity is obtained at 3 wt% with the highest separation efficiency of photogenerated electron-hole pairs. Integrating the physicochemical and photocatalytic properties, the factors controlling the photocatalytic activity of GQD/AgVO{sub 3} heterojunctions are discussed in detail. Moreover, potential photocatalytic degradation mechanisms of IBP via GQD/AgVO{sub 3} heterojunctions under visible light are proposed.

  10. Photocatalytic degradation of cylindrospermopsin under UV-A, solar and visible light using TiO2. Mineralization and intermediate products.

    Science.gov (United States)

    Fotiou, Theodora; Triantis, Theodoros; Kaloudis, Triantafyllos; Hiskia, Anastasia

    2015-01-01

    Cyanobacteria (blue-green algae) are considered an important water quality problem, since several genera can produce toxins, called cyanotoxins that are harmful to human health. Cylindrospermopsin (CYN) is an alkaloid-like potent cyanotoxin that has been reported in water reservoirs and lakes worldwide. In this paper the removal of CYN from water by UV-A, solar and visible light photocatalysis was investigated. Two different commercially available TiO2 photocatalysts were used, i.e., Degussa P25 and Kronos-vlp7000. Complete degradation of CYN was achieved with both photocatalysts in 15 and 40 min under UV-A and 40 and 120 min under solar light irradiation, for Degussa P25 and Kronos vlp-7000 respectively. Experiments in the absence of photocatalysts showed that direct photolysis was negligible. Under visible light irradiation only the Kronos vlp-7000 which is a visible light activated catalyst was able to degrade CYN. A number of intermediates were identified and a complete degradation pathway is proposed, leading to the conclusion that hydroxyl radical attack is the main mechanism followed. TOC and inorganic ions (NO2-, NO3-, SO4(2-) and NH4+) determinations suggested that complete mineralization of CYN was achieved under UV-A in the presence of Degussa P25. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Light

    DEFF Research Database (Denmark)

    Prescott, N.B.; Kristensen, Helle Halkjær; Wathes, C.M.

    2004-01-01

    This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality......This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality...

  12. HIV-1 tat protein recruits CIS to the cytoplasmic tail of CD127 to induce receptor ubiquitination and proteasomal degradation

    Energy Technology Data Exchange (ETDEWEB)

    Sugden, Scott, E-mail: scott.sugden@ircm.qc.ca [The Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada); Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5 (Canada); Ghazawi, Feras [The Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada); Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5 (Canada); MacPherson, Paul, E-mail: pmacpherson@toh.on.ca [The Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada); Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5 (Canada); Division of Infectious Diseases, The Ottawa Hospital General Campus, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada)

    2016-11-15

    HIV-1 Tat protein down regulates expression of the IL-7 receptor alpha-chain (CD127) from the surface of CD8 T cells resulting in impaired T cell proliferation and cytolytic capacity. We have previously shown that soluble Tat protein is taken up by CD8 T cells and interacts with the cytoplasmic tail of CD127 to induce receptor degradation. The N-terminal domain of Tat interacts with CD127 while the basic domain directs CD127 to the proteasome. We have also shown that upon IL-7 binding to its receptor, CD127 is phosphorylated resulting in CIS-mediated proteasomal degradation. Here, we show that Tat mimics this process by recruiting CIS to CD127 in the absence of IL-7 and receptor phosphorylation, leading to CD127 ubiquitination and degradation. Tat therefore acts as an adapter to induce cellular responses under conditions where they may not otherwise occur. Thusly, Tat reduces IL-7 signaling and impairs CD8 T cell survival and function. -- Highlights: •Soluble HIV-1 Tat decreases CD127 expression on CD8 T cells, causing dysfunction. •Tat induces CD127 ubiquitination without activating IL-7 signaling. •Tat binds CD127 and recruits the E3 ubiquitin ligase CIS via its basic domain. •Tat hijacks a normal cellular mechanism to degrade CD127 without IL-7 signaling.

  13. HIV-1 tat protein recruits CIS to the cytoplasmic tail of CD127 to induce receptor ubiquitination and proteasomal degradation

    International Nuclear Information System (INIS)

    Sugden, Scott; Ghazawi, Feras; MacPherson, Paul

    2016-01-01

    HIV-1 Tat protein down regulates expression of the IL-7 receptor alpha-chain (CD127) from the surface of CD8 T cells resulting in impaired T cell proliferation and cytolytic capacity. We have previously shown that soluble Tat protein is taken up by CD8 T cells and interacts with the cytoplasmic tail of CD127 to induce receptor degradation. The N-terminal domain of Tat interacts with CD127 while the basic domain directs CD127 to the proteasome. We have also shown that upon IL-7 binding to its receptor, CD127 is phosphorylated resulting in CIS-mediated proteasomal degradation. Here, we show that Tat mimics this process by recruiting CIS to CD127 in the absence of IL-7 and receptor phosphorylation, leading to CD127 ubiquitination and degradation. Tat therefore acts as an adapter to induce cellular responses under conditions where they may not otherwise occur. Thusly, Tat reduces IL-7 signaling and impairs CD8 T cell survival and function. -- Highlights: •Soluble HIV-1 Tat decreases CD127 expression on CD8 T cells, causing dysfunction. •Tat induces CD127 ubiquitination without activating IL-7 signaling. •Tat binds CD127 and recruits the E3 ubiquitin ligase CIS via its basic domain. •Tat hijacks a normal cellular mechanism to degrade CD127 without IL-7 signaling.

  14. Thermally induced degradation of sulfur-containing aliphatic glucosinolates in broccoli sprouts (Brassica oleracea var. italica) and model systems.

    Science.gov (United States)

    Hanschen, Franziska S; Platz, Stefanie; Mewis, Inga; Schreiner, Monika; Rohn, Sascha; Kroh, Lothar W

    2012-03-07

    Processing reduces the glucosinolate (GSL) content of plant food, among other aspects due to thermally induced degradation. Since there is little information about the thermal stability of GSL and formation of corresponding breakdown products, the thermally induced degradation of sulfur-containing aliphatic GSL was studied in broccoli sprouts and with isolated GSL in dry medium at different temperatures as well as in aqueous medium at different pH values. Desulfo-GSL have been analyzed with HPLC-DAD, while breakdown products were estimated using GC-FID. Whereas in the broccoli sprouts structural differences of the GSL with regard to thermal stability exist, the various isolated sulfur-containing aliphatic GSL degraded nearly equally and were in general more stable. In broccoli sprouts, methylsulfanylalkyl GSL were more susceptible to degradation at high temperatures, whereas methylsulfinylalkyl GSL were revealed to be more affected in aqueous medium under alkaline conditions. Besides small amounts of isothiocyanates, the main thermally induced breakdown products of sulfur-containing aliphatic GSL were nitriles. Although they were most rapidly formed at comparatively high temperatures under dry heat conditions, their highest concentrations were found after cooking in acidic medium, conditions being typical for domestic processing.

  15. Laser induced breakdown spectroscopy for analysis and characterization of degradation pathologies of Roman glasses

    Energy Technology Data Exchange (ETDEWEB)

    Palomar, T. [Instituto de Historia, Centro de Ciencias Humanas y Sociales, CSIC, C/Albasanz 26-28, 28037 Madrid (Spain); Oujja, M., E-mail: m.oujja@iqfr.csic.es [Instituto de Química Física Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain); García-Heras, M.; Villegas, M.A. [Instituto de Historia, Centro de Ciencias Humanas y Sociales, CSIC, C/Albasanz 26-28, 28037 Madrid (Spain); Castillejo, M. [Instituto de Química Física Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain)

    2013-09-01

    The feasibility and possibilities of laser induced breakdown spectroscopy (LIBS) in the full study of non-destructible historic glasses have been explored in the present work. Thirteen Roman glass samples, including seven entire glass beads, from the ancient town of Augusta Emerita (SW Spain) were characterized by LIBS in combination with other conventional techniques, such as scanning electron microscopy/energy dispersive X-ray spectrometry, X-ray fluorescence and ultraviolet–visible spectrophotometry. LIBS stratigraphic analysis, carried out by the application of successive laser pulses on the same spot, has been mainly targeted at characterizing particular features of non-destructible historic glasses, such as bulk chemical composition, surface degradation pathologies (dealkalinization layers and deposits), chromophores, and opacifying elements. The obtained data demonstrate that LIBS can be a useful and alternative technique for spectroscopic studies of historical glasses, especially for those conserved under burial conditions and when it deals with studying non-destructible samples. - Highlights: • Determination of chromophores and opacifiers in non-destructible glass by LIBS • Manganese is determined as principal component of dark deposits. • Antimony appears in all decorations while lead is only present in yellow ones. • Stratigraphic analysis enables the identification of dealkalinization layers.

  16. Bio-Environment-Induced Degradation and Failure of Internal Fixation Implants.

    Science.gov (United States)

    Zhou, Yan; Perkins, Luke A; Wang, Guodong; Zhou, Dongsheng; Liang, Hong

    2015-10-15

    Internal fixations provide fast healing but their failure remains problematic to patients. Here, we report an experimental study in failure of three typical cases of metals: a bent intramedullary stainless steel nail, a broken exterior pure Ti plate, and a broken intramedullary stainless steel nail. Characterization of the bent nail indicates that those metals are vulnerable to corrosion with the evidence of increased surface roughness and embrittlement. Depredated surface of the Ti plate resulted debris particles in the surrounding tissue of 15.2 ± 6.5 μm in size. Nanoparticles were observed in transmission electron microscope. The electron diffraction pattern of the debris indicates a combination of nanocrystalline and amorphous phases. The failure mode of the broken nail made of stainless steel was found to be fatigue initiated from the surface. This study clearly shows the biological-attack induced surface degradation resulting in debris and fatigue. Future design and selection of implant materials should consider such factors for improvement.

  17. Laser induced breakdown spectroscopy for analysis and characterization of degradation pathologies of Roman glasses

    International Nuclear Information System (INIS)

    Palomar, T.; Oujja, M.; García-Heras, M.; Villegas, M.A.; Castillejo, M.

    2013-01-01

    The feasibility and possibilities of laser induced breakdown spectroscopy (LIBS) in the full study of non-destructible historic glasses have been explored in the present work. Thirteen Roman glass samples, including seven entire glass beads, from the ancient town of Augusta Emerita (SW Spain) were characterized by LIBS in combination with other conventional techniques, such as scanning electron microscopy/energy dispersive X-ray spectrometry, X-ray fluorescence and ultraviolet–visible spectrophotometry. LIBS stratigraphic analysis, carried out by the application of successive laser pulses on the same spot, has been mainly targeted at characterizing particular features of non-destructible historic glasses, such as bulk chemical composition, surface degradation pathologies (dealkalinization layers and deposits), chromophores, and opacifying elements. The obtained data demonstrate that LIBS can be a useful and alternative technique for spectroscopic studies of historical glasses, especially for those conserved under burial conditions and when it deals with studying non-destructible samples. - Highlights: • Determination of chromophores and opacifiers in non-destructible glass by LIBS • Manganese is determined as principal component of dark deposits. • Antimony appears in all decorations while lead is only present in yellow ones. • Stratigraphic analysis enables the identification of dealkalinization layers

  18. Bio-Environment-Induced Degradation and Failure of Internal Fixation Implants

    Directory of Open Access Journals (Sweden)

    Yan Zhou

    2015-10-01

    Full Text Available Internal fixations provide fast healing but their failure remains problematic to patients. Here, we report an experimental study in failure of three typical cases of metals: a bent intramedullary stainless steel nail, a broken exterior pure Ti plate, and a broken intramedullary stainless steel nail. Characterization of the bent nail indicates that those metals are vulnerable to corrosion with the evidence of increased surface roughness and embrittlement. Depredated surface of the Ti plate resulted debris particles in the surrounding tissue of 15.2 ± 6.5 μm in size. Nanoparticles were observed in transmission electron microscope. The electron diffraction pattern of the debris indicates a combination of nanocrystalline and amorphous phases. The failure mode of the broken nail made of stainless steel was found to be fatigue initiated from the surface. This study clearly shows the biological-attack induced surface degradation resulting in debris and fatigue. Future design and selection of implant materials should consider such factors for improvement.

  19. Autophagic degradation of aquaporin-2 is an early event in hypokalemia-induced nephrogenic diabetes insipidus.

    Science.gov (United States)

    Khositseth, Sookkasem; Uawithya, Panapat; Somparn, Poorichaya; Charngkaew, Komgrid; Thippamom, Nattakan; Hoffert, Jason D; Saeed, Fahad; Michael Payne, D; Chen, Shu-Hui; Fenton, Robert A; Pisitkun, Trairak

    2015-12-17

    Hypokalemia (low serum potassium level) is a common electrolyte imbalance that can cause a defect in urinary concentrating ability, i.e., nephrogenic diabetes insipidus (NDI), but the molecular mechanism is unknown. We employed proteomic analysis of inner medullary collecting ducts (IMCD) from rats fed with a potassium-free diet for 1 day. IMCD protein quantification was performed by mass spectrometry using a label-free methodology. A total of 131 proteins, including the water channel AQP2, exhibited significant changes in abundance, most of which were decreased. Bioinformatic analysis revealed that many of the down-regulated proteins were associated with the biological processes of generation of precursor metabolites and energy, actin cytoskeleton organization, and cell-cell adhesion. Targeted LC-MS/MS and immunoblotting studies further confirmed the down regulation of 18 selected proteins. Electron microscopy showed autophagosomes/autophagolysosomes in the IMCD cells of rats deprived of potassium for only 1 day. An increased number of autophagosomes was also confirmed by immunofluorescence, demonstrating co-localization of LC3 and Lamp1 with AQP2 and several other down-regulated proteins in IMCD cells. AQP2 was also detected in autophagosomes in IMCD cells of potassium-deprived rats by immunogold electron microscopy. Thus, enhanced autophagic degradation of proteins, most notably including AQP2, is an early event in hypokalemia-induced NDI.

  20. Mechanism of radiation-induced degradation in mechanical properties of polymer matrix composites

    International Nuclear Information System (INIS)

    Egusa, Shigenori

    1988-01-01

    Four kinds of polymer matrix composites (filler, E-glass or carbon fibre cloth; matrix, epoxy or polyimide resin) and pure epoxy and polyimide resins were irradiated with 60 Co γ-rays or 2 MeV electrons at room temperature. Mechanical tests were then carried out at 77K and at room temperature. Following irradiation, the Young's (tensile) modulus of these composites and pure resins remains practically unchanged even at 170 MGy for both test temperatures. The ultimate strength, however, decreases appreciably with increasing dose. The dose dependence of the composite strength depends not only on the combination of fibre and matrix in the composite but also on the test temperature. A relationship is found between the composite ultimate strain and the matrix ultimate strain, thus indicating that the dose dependence of the composite strength is virtually determined by a change in the matrix ultimate strain due to irradiation. Based on this finding, we propose a mechanism of radiation-induced degradation of a polymer matrix composite in order to explain the dose dependence of the composite strength measured at 77 K and at room temperature. (author)

  1. Graphene oxide–CdS composite with high photocatalytic degradation and disinfection activities under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Peng; Liu, Jincheng [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Sun, Darren Delai, E-mail: DDSUN@ntu.edu.sg [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Ng, Wunjern [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Nanyang Environment and Water Research Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2013-04-15

    Highlights: ► GO–CdS composites were prepared through a novel two-phase mixing method. ► Uniform deposition of CdS nanoparticles on GO sheets. ► Reduced charge recombination rate. ► Enhanced photo-stability. ► High photodegradation and disinfection efficiency. -- Abstract: Graphene oxide (GO)–CdS composites were synthesized via a novel two-phase mixing method successfully. CdS nanoparticles were uniformly self-assembled on GO sheets at water/toluene interface. The photocatalytic degradation (photodegradation) and disinfection activities of GO–CdS composites were investigated thoroughly. The results show that GO–CdS composites exhibit higher efficiency in photodegradation of various water pollutants than pure CdS nanoparticles under visible light irradiation. In addition, the interactions between GO sheets and CdS nanoparticles inhibit the photo-corrosion of CdS and leaching of Cd{sup 2+}. Only 3.5 wt% Cd{sup 2+} of GO–CdS was leached out after photodegradation, while 38.6 wt% Cd{sup 2+} of CdS was lost into aqueous solution. Furthermore, the disinfection activity of GO–CdS composites was investigated for the first time. Nearly 100% of both Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) were killed within 25 min under visible light irradiation. The excellent performances of GO–CdS composites can be attributed to that (1) effective charge transfer from CdS to GO reduces the recombination rate of photo-generated electron–hole pairs; (2) uniform deposition of CdS on GO sheets eliminates aggregation of CdS nanoparticles; and (3) the strong interactions between GO and CdS enhancing the durability of GO–CdS composites. Finally, the mechanism behind these excellent performances was verified by transient photocurrent measurement and further confirmed by ESR technique as well as employing a radical scavenging species – dimethyl sulfoxide (DMSO)

  2. Graphene oxide–CdS composite with high photocatalytic degradation and disinfection activities under visible light irradiation

    International Nuclear Information System (INIS)

    Gao, Peng; Liu, Jincheng; Sun, Darren Delai; Ng, Wunjern

    2013-01-01

    Highlights: ► GO–CdS composites were prepared through a novel two-phase mixing method. ► Uniform deposition of CdS nanoparticles on GO sheets. ► Reduced charge recombination rate. ► Enhanced photo-stability. ► High photodegradation and disinfection efficiency. -- Abstract: Graphene oxide (GO)–CdS composites were synthesized via a novel two-phase mixing method successfully. CdS nanoparticles were uniformly self-assembled on GO sheets at water/toluene interface. The photocatalytic degradation (photodegradation) and disinfection activities of GO–CdS composites were investigated thoroughly. The results show that GO–CdS composites exhibit higher efficiency in photodegradation of various water pollutants than pure CdS nanoparticles under visible light irradiation. In addition, the interactions between GO sheets and CdS nanoparticles inhibit the photo-corrosion of CdS and leaching of Cd 2+ . Only 3.5 wt% Cd 2+ of GO–CdS was leached out after photodegradation, while 38.6 wt% Cd 2+ of CdS was lost into aqueous solution. Furthermore, the disinfection activity of GO–CdS composites was investigated for the first time. Nearly 100% of both Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) were killed within 25 min under visible light irradiation. The excellent performances of GO–CdS composites can be attributed to that (1) effective charge transfer from CdS to GO reduces the recombination rate of photo-generated electron–hole pairs; (2) uniform deposition of CdS on GO sheets eliminates aggregation of CdS nanoparticles; and (3) the strong interactions between GO and CdS enhancing the durability of GO–CdS composites. Finally, the mechanism behind these excellent performances was verified by transient photocurrent measurement and further confirmed by ESR technique as well as employing a radical scavenging species – dimethyl sulfoxide (DMSO)

  3. Blue and Green Light-Induced Phototropism in Arabidopsis thaliana and Lactuca sativa L. Seedlings 1

    Science.gov (United States)

    Steinitz, Benjamin; Ren, Zhangling; Poff, Kenneth L.

    1985-01-01

    Exposure time-response curves for blue and green light-induced phototropic bending in hypocotyls of Arabidopsis thaliana (L.) Heynh. and Lactuca sativa L. seedlings are presented. These seedlings show significant phototropic sensitivity up to 540 to 550 nanometers. Since wave-lengths longer than 560 nanometers do not induce phototropic bending, it is suggested that the response to 510 to 550 nanometers light is mediated by the specific blue light photoreceptor of phototropism. We advise care in the use of green `safelights' for studies of phototropism. PMID:16664021

  4. Weak light emission of soft tissues induced by heating

    Science.gov (United States)

    Spinelli, Antonello E.; Durando, Giovanni; Boschi, Federico

    2018-04-01

    The main goal of this work is to show that soft tissue interaction with high-intensity focused ultrasound (HIFU) or direct heating leads to a weak light emission detectable using a small animal optical imaging system. Our results show that the luminescence signal is detectable after 30 min of heating, resembling the time scale of delayed luminescence. The imaging of a soft tissue after heating it using an HIFU field shows that the luminescence pattern closely matches the shape of the cone typical of the HIFU beam. We conclude that heating a soft tissue using two different sources leads to the emission of a weak luminescence signal from the heated region with a decay half-life of a few minutes (4 to 6 min). The origin of such light emission needs to be further investigated.

  5. Tunneling-Electron-Induced Light Emission from Single Gold Nanoclusters.

    Science.gov (United States)

    Yu, Arthur; Li, Shaowei; Czap, Gregory; Ho, W

    2016-09-14

    The coupling of tunneling electrons with the tip-nanocluster-substrate junction plasmon was investigated by monitoring light emission in a scanning tunneling microscope (STM). Gold atoms were evaporated onto the ∼5 Å thick Al2O3 thin film grown on the NiAl (110) surface where they formed nanoclusters 3-7 nm wide. Scanning tunneling spectroscopy (STS) of these nanoclusters revealed quantum-confined electronic states. Spatially resolved photon imaging showed localized emission hot spots. Size dependent study and light emission from nanocluster dimers further support the viewpoint that coupling of tunneling electrons to the junction plasmon is the main radiative mechanism. These results showed the potential of the STM to reveal the electronic and optical properties of nanoscale metallic systems in the confined geometry of the tunnel junction.

  6. Light-induced cell separation in a tailored optical landscape

    International Nuclear Information System (INIS)

    Paterson, L.; Milne, G.; Garcés-Chávez, V.; Tatarkova, S. A.; Sibbett, W.; Dholakia, K.; Papagiakoumou, E.; Gunn-Moore, F. J.; Bryant, P. E.; Riches, A. C.

    2005-01-01

    We demonstrate passive optical sorting of cell populations in the absence of any externally driven fluid flow. Specifically, we report the movement of erythrocytes and lymphocytes in an optical landscape, consisting of a circularly symmetric light pattern created by a Bessel light beam. These distinct cell populations move, spontaneously and differentially, across the underlying periodic optical landscape. Thus, we were able to separate lymphocytes from a mixed population of cells containing erythrocytes and then collect the lymphocytes in a microcapillary reservoir. We also demonstrate an enhanced form of this separation that exploits the polarizability of silica microspheres by attaching spheres coated with antibodies to cell surface markers to a subpopulation of lymphocytes. These techniques may be applied using standard laboratory apparatus.

  7. Differential contributions of ubiquitin-modified APOBEC3G lysine residues to HIV-1 Vif-induced degradation

    OpenAIRE

    Turner, Tiffany; Shao, Qiujia; Wang, Weiran; Wang, Yudi; Wang, Chenliang; Kinlock, Ballington; Liu, Bindong

    2016-01-01

    Apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (A3G) is a host restriction factor that impedes HIV-1 replication. Viral integrity is salvaged by HIV-1 virion infectivity factor (Vif), which mediates A3G polyubiquitination and subsequent cellular depletion. Previous studies have implied that A3G polyubiquitination is essential for Vif-induced degradation. However, the contribution of polyubiquitination to the rate of A3G degradation remains unclear. Here we show that A3G po...

  8. Visible light responsive Cu2MoS4 nanosheets incorporated reduced graphene oxide for efficient degradation of organic pollutant

    Science.gov (United States)

    Rameshbabu, R.; Vinoth, R.; Navaneethan, M.; Harish, S.; Hayakawa, Y.; Neppolian, B.

    2017-10-01

    Visible light active copper molybdenum sulfide (Cu2MoS4) nanosheets were successfully anchored on reduced graphene oxide (rGO) using facile hydrothermal method. During the hydrothermal reaction, reduction of graphene oxide into rGO and the formation of Cu2MoS4 nanosheets were successfully obtained. The charge transfer interaction between the rGO sheets and Cu2MoS4 nanosheets extended the absorption to visible region in comparison with bare Cu2MoS4 nanosheets i.e without rGO sheets. Furthermore, the notable photoluminescence quenching observed for Cu2MoS4/rGO nanocomposite revealed the effective role of rGO towards the significant inhibition of electron-hole pair recombination. The photocatalytic efficiencies of bare Cu2MoS4 and Cu2MoS4/rGO nanocomposite was evaluated for the degradation of methyl orange dye under visible irradiation (λ > 420 nm). A maximum photodegradation efficiency of 99% was achieved for Cu2MoS4/rGO nanocomposite, while only 64% photodegradation was noted for bare Cu2MoS4. The enhanced optical absorption in visible region, high surface area, and low charge carrier recombination in the presence of rGO sheets were the main reasons for the enhancement in photodegardation of MO dye. In addition, the resultant Cu2MoS4/rGO nanocomposite was found to be reusable for five successive cycles without significant loss in its photocatalytic performance.

  9. Light-induced circular birefringence in cyanoazobenzene side-chain liquid-crystalline polyester films

    DEFF Research Database (Denmark)

    Naydenova, I; Nikolova, L; Ramanujam, P.S.

    1999-01-01

    We report the inducement of large circular birefringence (optical activity) in films of a cyanoazobenzene side-chain liquid-crystalline polyester on illumination with circularly polarized light. The polyester has no chiral groups and is initially isotropic. The induced optical rotation is up to 5...

  10. Light-induced lattice expansion leads to high-efficiency perovskite solar cells

    Science.gov (United States)

    Tsai, Hsinhan; Asadpour, Reza; Blancon, Jean-Christophe; Stoumpos, Constantinos C.; Durand, Olivier; Strzalka, Joseph W.; Chen, Bo; Verduzco, Rafael; Ajayan, Pulickel M.; Tretiak, Sergei; Even, Jacky; Alam, Muhammad Ashraf; Kanatzidis, Mercouri G.; Nie, Wanyi; Mohite, Aditya D.

    2018-04-01

    Light-induced structural dynamics plays a vital role in the physical properties, device performance, and stability of hybrid perovskite–based optoelectronic devices. We report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in situ structural and device characterizations reveal that light-induced lattice expansion benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5 to 20.5%. The lattice expansion leads to the relaxation of local lattice strain, which lowers the energetic barriers at the perovskite-contact interfaces, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion did not compromise the stability of these high-efficiency photovoltaic devices under continuous operation at full-spectrum 1-sun (100 milliwatts per square centimeter) illumination for more than 1500 hours.

  11. Light-induced attractive force between two metal bodies separated by a subwavelength slit

    International Nuclear Information System (INIS)

    Nesterov, Vladimir; Frumin, Leonid

    2011-01-01

    A novel light-induced attractive force which acts as a force with negative light pressure has been revealed. The force arises by the interaction of plasmon polaritons which are excited at the surface of metal when a transverse magnetic mode propagates through a subwavelength slit between two metal bodies. The estimation of the repulsive force acting on the metal walls of the slit in the case of subwavelength TE mode propagation along the slit is presented. The explicit analytical expressions of light-induced forces between two macroscopic metal bodies or films separated by a subwavelength slit have been derived. These forces could be used to manipulate metallic macro-, micro- and nano-objects in vacuum or in a dielectric medium. Estimations of these light-induced forces show that the forces are sufficient for measurements and practical applications

  12. The highly enhanced visible light photocatalytic degradation of gaseous o-dichlorobenzene through fabricating like-flowers BiPO{sub 4}/BiOBr p-n heterojunction composites

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Xuejun [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Dong, Yuying, E-mail: dongy@dlnu.edu.cn [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Zhang, Xiaodong, E-mail: fatzhxd@126.com [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, 200093 (China); Cui, Yubo; Ou, Xiaoxia [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian, 116600 (China); Qi, Xiaohui [College of Life Science, Dalian Nationalities University, Dalian, 116600 (China)

    2017-01-01

    Highlights: • Like-flowers BiPO{sub 4}/BiOBr was fabricated by mixing in solvent method. • o-Dichlorobenzene removal efficiency was 53.6% using BiPO{sub 4}/BiOBr. • The p–n junction improved o-dichlorobenzene degradation activity. - Abstract: In this paper, in order to enhance photo-induced electron-hole pairs separation of BiOBr, flowers-like BiPO{sub 4}/BiOBr p-n heterojunction composites was fabricated by a mixing in solvent method. The as-prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV–vis absorption spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and N{sub 2} adsorption-desorption. Meanwhile, their photocatalytic properties were investigated by the degradation of gaseous o-dichlorobenzene under visible light irradiation. Due to its strong adsorption capacity and the formation of p-n heterojunction, compared with BiPO{sub 4} and BiOBr, the BiPO{sub 4}/BiOBr composites showed higher photocatalytic activity in the degradation of gaseous o-DCB under visible light. Among them, 2% BiPO{sub 4}/BiOBr showed the maximum value of the activity, whose degradation rate was about 2.6 times as great as the pure BiOBr. Furthermore, the OH· was confirmed the main active species during the photocatalytic process by the trapping experiments. The outstanding performance indicated that the photocatalysts could be applied to air purification for chlorinated volatile organic compound.

  13. Gas-liquid hybrid discharge-induced degradation of diuron in aqueous solution.

    Science.gov (United States)

    Feng, Jingwei; Zheng, Zheng; Luan, Jingfei; Li, Kunquan; Wang, Lianhong; Feng, Jianfang

    2009-05-30

    Degradation of diuron in aqueous solution by gas-liquid hybrid discharge was investigated for the first time. The effect of output power intensity, pH value, Fe(2+) concentration, Cu(2+) concentration, initial conductivity and air flow rate on the degradation efficiency of diuron was examined. The results showed that the degradation efficiency of diuron increased with increasing output power intensity and increased with decreasing pH values. In the presence of Fe(2+), the degradation efficiency of diuron increased with increasing Fe(2+) concentration. The degradation efficiency of diuron was decreased during the first 4 min and increased during the last 10 min with adding of Cu(2+). Decreasing the initial conductivity and increasing the air flow rate were favorable for the degradation of diuron. Degradation of diuron by gas-liquid hybrid discharge fitted first-order kinetics. The pH value of the solution decreased during the reaction process. Total organic carbon removal rate increased in the presence of Fe(2+) or Cu(2+). The generated Cl(-1), NH(4)(+), NO(3)(-), oxalic acid, acetic acid and formic acid during the degradation process were also detected. Based on the detected Cl(-1) and other intermediates, a possible degradation pathway of diuron was proposed.

  14. [Catalytic Degradation of Diclofenac Sodium over the Catalyst of 3D Flower-like alpha-FeOOH Synergized with H2O2 Under Visible Light Irradiation].

    Science.gov (United States)

    Xu, Jun-ge; Li, Yun-qin; Huang, Hua-shan; Yuan, Bao-ling; Cui, Hao-jie; Fu, Ming-lai

    2015-06-01

    Three dimensional (3D) flower-like alpha-FeOOH nanomaterials were prepared by oil bath reflux method using FeSO4, urea, ethanol and water, and the products which were characterized by XRD, FT-IR and SEM techniques. The SEM images showed that the 3D flower-like samples consisted of nanorods with a length of 400-500 nm and a diameter of 40-60 nm. The catalytic performance of the samples was evaluated by catalytic degradation of diclofenac sodium using H2O2 as the oxidant under simulated visible light. The results showed that the as-prepared samples presented high efficient catalytic performances, and more than 99% of the initial diclofenac sodium (30 mg x L(-1)) was degraded in 90 min. A radical mechanism can be proposed for the catalytic degradation of diclofenac sodium solution.

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

    Science.gov (United States)

    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.

  16. Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2

    International Nuclear Information System (INIS)

    Triantis, T.M.; Fotiou, T.; Kaloudis, T.; Kontos, A.G.; Falaras, P.; Dionysiou, D.D.; Pelaez, M.; Hiskia, A.

    2012-01-01

    Highlights: ► N-TiO 2 exhibited effective degradation of MC-LR under UV-A, solar and visible light. ► Complete photocatalytic mineralization of MC-LR was achieved under UV-A and solar light. ► The organic nitrogen is mainly released as ammonium and nitrate ions. - Abstract: In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO 2 (N-TiO 2 ) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO 2 , Kronos and reference TiO 2 nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO 2 followed by N-TiO 2 with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO 2 nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO 2 for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO 2 displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO 2 − , NO 3 − and NH 4 + ) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light.

  17. Preparation of Ag–AgBr/TiO2–graphene and its visible light photocatalytic activity enhancement for the degradation of polyacrylamide

    International Nuclear Information System (INIS)

    Rong, Xinshan; Qiu, Fengxian; Zhang, Chen; Fu, Liang; Wang, Yuanyuan; Yang, Dongya

    2015-01-01

    Highlights: • Ag–AgBr/TiO 2 –graphene (AATG) composite photocatalyst was prepared. • AATG was applied to photocatalytic degradation of polyacrylamide (PAM). • Degradation condition such as mass ratio of TiO 2 /graphene, dose, pH and time, was investigated. • The AATG composite photocatalyst can be separated from system effectively and easily. • The prepared AATG exhibits significant photocatalytic activity after five successive recycles. - Abstract: In current work, TiO 2 was modified by Ag/AgBr semiconductor and graphene to enhance its photocatalytic activity for the degradation of polyacrylamide (PAM). Ag–AgBr/TiO 2 –graphene (AATG) composite photocatalysts were prepared by the deposition–precipitation method combining a subsequent calcination process. The structure, surface morphology and chemical composition of AATG composite photocatalysts were investigated by XRD, XPS, DRS, PL, SEM, EDS, TEM, and HRTEM methods. XRD and XPS results show that Ag 0 is generated from Ag + under visible light irradiation. Degradation of PAM was chosen to evaluate photocatalytic activity using AATG composite as photocatalysts. The conditions such as mass ratio of TiO 2 /graphene, catalyst dose, pH and contact time, were investigated for the degradation of PAM. Possible pathway and mechanism were proposed for photocatalytic degradation of PAM over AATG composite photocatalyst under visible light irradiation. The prepared AATG composite photocatalyst can be separated from system effectively and easily; and exhibits significant photocatalytic activity after five successive recycles, which confirmed that the components of the AATG are not photo decomposed and the structure is stable during the photocatalytic process

  18. Properties of light induced EPR signals in enamel and their possible interference with gamma-induced signals

    International Nuclear Information System (INIS)

    Sholom, S.V.; Chumak, V.V.; Haskell, E.H.; Hayes, R.B.; Kenner, G.H.

    1998-01-01

    Exposure of tooth enamel to natural and artificial UV light results in stable EPR signals with g-factors of 1.9985, 2.0018, 2.0045, 2.0052 and 2.0110. The first three signals correspond to the parallel and perpendicular components of the radiation induced or dosimetric signal and the native signal reported in dosimetry and dating studies. The latter two signals were found to be sensitive to both gamma-ray and sunlight exposure, however, their responses to light differed from that to radiation, giving rise to the possibility of using them as indicators of the dose-equivalent resulting from light exposure

  19. Quick photo-Fenton degradation of phenolic compounds by Cu/Al2O3-MCM-41 under visible light irradiation: small particle size, stabilization of copper, easy reducibility of Cu and visible light active material.

    Science.gov (United States)

    Pradhan, Amaresh C; Nanda, Binita; Parida, K M; Das, Mira

    2013-01-14

    The present study reports the photo-Fenton degradation of phenolic compounds (phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol) in aqueous solution using mesoporous Cu/Al(2)O(3)-MCM-41 nanocomposite as a heterogeneous photo-Fenton-like catalyst. The in situ incorporation of mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (sol-gel method) forms Al(2)O(3)-MCM-41 and wetness impregnation of Cu(II) on Al(2)O(3)-MCM-41 generates mesoporous Cu/Al(2)O(3)-MCM-41 composite. The effects of pH and H(2)O(2) concentration on degradation of phenol, 2-chloro-4-nitrophenol and 4-chloro-2-nitrophenol are studied. Kinetics analysis shows that the photocatalytic degradation reaction follows a first-order rate equation. Mesoporous 5 Cu/Al(2)O(3)-MCM-41 is found to be an efficient photo-Fenton-like catalyst for the degradation of phenolic compounds. It shows nearly 100% degradation in 45 min at pH 4. The combined effect of small particle size, stabilization of Cu(2+) on the support Al(2)O(3)-MCM-41, ease reducibility of Cu(2+) and visible light activeness are the key factors for quick degradation of phenolic compounds by Cu/Al(2)O(3)-MCM-41.

  20. Tumor Necrosis Factor-α Induced Apoptosis in U937 Cells Promotes Cathepsin D-Independent Stefin B Degradation.

    Science.gov (United States)

    Bidovec, Katja; Božič, Janja; Dolenc, Iztok; Turk, Boris; Turk, Vito; Stoka, Veronika

    2017-12-01

    Lysosomal cathepsins were previously found to be involved in tumor necrosis factor-α (TNFα)-induced apoptosis. However, there are opposing views regarding their role as either initiators or amplifiers of the signaling cascade as well as the order of molecular events during this process. In this study, we investigated the role of cathepsin D (catD) in TNFα/cycloheximide-induced apoptosis in U937 human monocytic cells. TNFα-induced apoptosis proceeds through caspase-8 activation, processing of the pro-apoptotic molecule Bid, mitochondrial membrane permeabilization, and caspase-3 activation. The translocation of lysosomal catD into the cytosol was a late event, suggesting that lysosomal membrane permeabilization and the release of cathepsins are not required for the induction of apoptosis, but rather amplifies the process through the generation of reactive oxygen species. For the first time, we show that apoptosis is accompanied by degradation of the cysteine cathepsin inhibitor stefin B (StfB). CatD did not exhibit a crucial role in this step. However, this degradation was partially prevented through pre-incubation with the antioxidant N-acetyl cysteine, although it did not prevent apoptosis and its progression. These results suggest that the degradation of StfB, as a response to TNFα, could induce a cell death amplification effect as a result of progressive damage to lysosomes during TNFα treatment. J. Cell. Biochem. 118: 4813-4820, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. GSK3 is required for rapalogs to induce degradation of some oncogenic proteins and to suppress cancer cell growth.

    Science.gov (United States)

    Koo, Junghui; Wang, Xuerong; Owonikoko, Taofeek K; Ramalingam, Suresh S; Khuri, Fadlo R; Sun, Shi-Yong

    2015-04-20

    The single-agent activity of rapalogs (rapamycin and its analogues) in most tumor types has been modest at best. The underlying mechanisms are largely unclear. In this report, we have uncovered a critical role of GSK3 in regulating degradation of some oncogenic proteins induced by rapalogs and cell sensitivity to rapalogs. The basal level of GSK3 activity was positively correlated with cell sensitivity of lung cancer cell lines to rapalogs. GSK3 inhibition antagonized rapamycin's growth inhibitory effects both in vitro and in vivo, while enforced activation of GSK3β sensitized cells to rapamycin. GSK3 inhibition rescued rapamcyin-induced reduction of several oncogenic proteins such as cyclin D1, Mcl-1 and c-Myc, without interfering with the ability of rapamycin to suppress mTORC1 signaling and cap binding. Interestingly, rapamycin induces proteasomal degradation of these oncogenic proteins, as evidenced by their decreased stabilities induced by rapamcyin and rescue of their reduction by proteasomal inhibition. Moreover, acute or short-time rapamycin treatment dissociated not only raptor, but also rictor from mTOR in several tested cell lines, suggesting inhibition of both mTORC1 and mTORC2. Thus, induction of GSK3-dependent degradation of these oncogenic proteins is likely secondary to mTORC2 inhibition; this effect should be critical for rapamycin to exert its anticancer activity.

  2. Blue light irradiation-induced oxidative stress in vivo via ROS generation in rat gingival tissue.

    Science.gov (United States)

    Yoshida, Ayaka; Shiotsu-Ogura, Yukako; Wada-Takahashi, Satoko; Takahashi, Shun-suke; Toyama, Toshizo; Yoshino, Fumihiko

    2015-10-01

    It has been reported that oxidative stress with reactive oxygen species (ROS) generation is induced by blue light irradiation to a living body. Only limited research has been reported in dental field on the dangers of blue light, mostly focusing on cytotoxicity associated with heat injury of dental pulp. We thus performed an in vivo study on oral tissue exposed to blue light. ROS generated upon blue light irradiation of flavin adenine dinucleotide were measured by electron spin resonance spectroscopy. After blue light irradiation, the palatal gingiva of Wistar rats were isolated. Collected samples were subjected to biochemical analysis of lipid peroxidation and glutathione. Singlet oxygen was generated by blue light irradiation, but was significantly quenched in an N-acetyl-L-cysteine (NAC) concentration-dependent manner. Blue light significantly accelerated oxidative stress and increased the oxidized glutathione levels in gingival tissue. These effects were also inhibited by NAC pre-administration. The results suggest that blue light irradiation at clinical levels of tooth bleaching treatment may enhance lipid peroxidation by the induction of oxidative stress and the consumption of a significant amount of intracellular glutathione. In addition, NAC might be an effective supplement for the protection of oral tissues against blue light irradiation-induced oxidative damage. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Self-assembly graphitic carbon nitride quantum dots anchored on TiO_2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light

    International Nuclear Information System (INIS)

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-01-01

    Highlights: • Carbon nitride quantum dots (CNQDs) were decorated onto TiO_2 nanotube arrays (NTAs). • The CNQDs/TiO_2 NTAs exhibits much improved photoelectrochemical activity. • The heterojunction displays efficient removal efficiencies for RhB and phenol. • Pollutants degradation mechanism over CNQDs/TiO_2 NTAs was clarified. - Abstract: In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO_2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO_2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO_2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation.

  4. Fe-N co-doped SiO2@TiO2 yolk-shell hollow nanospheres with enhanced visible light photocatalytic degradation

    Science.gov (United States)

    Wan, Hengcheng; Yao, Weitang; Zhu, Wenkun; Tang, Yi; Ge, Huilin; Shi, Xiaozhong; Duan, Tao

    2018-06-01

    SiO2@TiO2 yolk@shell hollow nanospheres (STNSs) is considered as an outstanding photocatalyst due to its tunable structure and composition. Based on this point, we present an unprecedentedly excellent photocatalytic property of STNSs toward tannic acid via a Fe-N co-doped strategy. Their morphologies, compositions, structure and properties are characterized. The Fe-N co-doped STNSs formed good hollow yolk@shell structure. The results show that the energy gap of the composites can be downgraded to 2.82 eV (pure TiO2 = 3.2 eV). Photocatalytic degradation of tannic acid (TA, 30 mg L-1) under visible light (380 nm TiO2 nanospheres, non-doped STNSs and N-doped STNSs, the Fe-N co-doped STNSs exhibits the highest activity, which can degrade 99.5% TA into CO2 and H2O in 80 min. The probable degradation mechanism of the composites is simultaneously proposed, the band gap of STNSs becomes narrow by co-doping Fe-N, so that the TiO2 shell can stimulate electrons under visible light exposure, generate the ions of radOH and radO2- with a strong oxidizing property. Therefore this approach works is much desired for radioactive organic wastewater photocatalytic degradation.

  5. Fabrication of Ag-decorated BiOBr-mBiVO4 dual heterojunction composite with enhanced visible light photocatalytic performance for degradation of malachite green

    Science.gov (United States)

    Regmi, Chhabilal; Dhakal, Dipesh; Kim, Tae-Ho; Yamaguchi, Takutaro; Wohn Lee, Soo

    2018-04-01

    A visible light active Ag-decorated BiVO4-BiOBr dual heterojunction photocatalyst was prepared using a facile hydrothermal method, followed by the photodeposition of Ag. The photocatalytic activity of the synthesized samples was investigated by monitoring the change in malachite green (MG) concentration upon visible light irradiation. The synthesized sample was highly effective for the degradation of non-biodegradable MG. The enhanced activity observed was ascribed to the efficient separation and transfer of charge carriers across the dual heterojunction structure as verified by photoluminescence measurements. The removal of MG was primarily initiated by hydroxyl radicals and holes based on scavenger’s effect. To gain insight into the degradation mechanism, both high performance liquid chromatography and high resolution-quantitative time of flight, electrospray ionization mass spectrometry measurements during the degradation process were carried out. The degradation primarily followed the hydroxylation and N-demethylation process. A possible reaction pathway is proposed on the basis of all the information obtained under various experimental conditions.

  6. Comparative studies on the degradation of aqueous 2-chloroaniline by O3 as well as by UV-light and γ-rays in the presence of ozone

    International Nuclear Information System (INIS)

    Winarno, Ermin Katrin; Getoff, Nikola

    2002-01-01

    Chlorinated anilines are frequently used in the industry as starting materials for chemical synthesis. Hence, such compounds can occur as pollutants in waste waters. In the present study 2-chloroaniline (2-ClA) was selected as the representative model for this class of compounds. The objectives of the work concerned 2-ClA degradation in water by ozonation as well as by photolysis (UV-light of 254 nm) and radiolysis (γ-rays) in the presence of ozone. In all three series of experiments, the same amount ozone was passed through the 2-ClA solution at pH=6.9 during the treatment. The degradation process was followed as a function of the action time and by chemical analysis of the major products. Based on the actinometry of the monochromatic UV-light (λ=254 nm, E=4.88 eV/hν) and dosimetry data, the obtained degradation yields and products by the three series of experiments are compared. It was established that the synergic effect of γ-rays and ozone leads to the most efficient degradation of 2-ClA, followed by UV/O 3 -combination and pure ozonation. The same sequence is also observed by cleavage of the Cl-atom. The formation of the other major products: ammonia, formaldehyde, oxalic acid and the total yield of carboxylic acids depend on the media. Probable reaction mechanisms are suggested for explanation of the experimental results

  7. Preparation of graphene/TiO2 composites by nonionic surfactant strategy and their simulated sunlight and visible light photocatalytic activity towards representative aqueous POPs degradation

    International Nuclear Information System (INIS)

    Li, Kexin; Xiong, Jingjing; Chen, Tong; Yan, Liushui; Dai, Yuhua; Song, Dongyang; Lv, Ying; Zeng, Zhenxing

    2013-01-01

    Highlights: ► A series of graphene/TiO 2 composites were developed by nonionic surfactant strategy. ► The textural property, optical property, and composition were well characterized. ► Aqueous POPs were degraded under simulated sunlight and visible light irradiation. ► The degradation mechanism and kinetics of aqueous POPs were studied in detail. ► Mineralization of aqueous POPs and recyclability of the composites were also tested. -- Abstract: A series of graphene/TiO 2 composites were fabricated using a single-step nonionic surfactant strategy combined with the solvothermal treatment technique. Their phase structure, morphology, porosity, optical absorption property, as well as composition and structure, were characterized. The as-prepared composites were successfully applied to degrade aqueous persistent organic pollutants (POPs) such as rhodamine B, aldicarb, and norfloxacin in simulated sunlight (λ > 320 nm) and visible light (λ > 400 nm) irradiation. The degradation mechanism and kinetics of aqueous POPs were studied in detail. The mineralization of aqueous POPs and the recyclability of the composites were also tested in the same condition

  8. Preparation and photocatalytic performance of Fe (III)-amidoximated PAN fiber complex for oxidative degradation of azo dye under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yongchun, E-mail: dye@tjpu.edu.cn [Division of Textile Chemistry and Ecology, School of Textile Science and Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou, 350002 (China); Han, Zhenbang [Division of Textile Chemistry and Ecology, School of Textile Science and Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); Liu, Chunyan [Division of Textile Chemistry and Ecology, School of Textile Science and Engineering, Tianjin Polytechnic University, Tianjin 300160 (China); State Key Laboratory Breeding Base of Photocatalysis, Fuzhou University, Fuzhou, 350002 (China); Du, Fang [Division of Textile Chemistry and Ecology, School of Textile Science and Engineering, Tianjin Polytechnic University, Tianjin 300160 (China)

    2010-04-15

    Polyacrylonitrile (PAN) fiber was modified with hydroxylamine hydrochloride to introduce amidoxime groups onto the fiber surface. These amidoxime groups were used to react with Fe (III) ions to prepare Fe (III)-amidoximated PAN fiber complex, which was characterized using SEM, XRD, FTIR, XPS, DMA, and DRS respectively. Then the photocatalytic activity of Fe-AO-PAN was evaluated in the degradation of a typical azo dye, C. I. Reactive Red 195 in the presence of H{sub 2}O{sub 2} under visible light irradiation. Moreover, the effect of the Fe content of Fe-AO-PAN on dye degradation was also investigated. The results indicated that Fe (III) ions can crosslink between the modified PAN fiber chains by the coordination of Fe (III) ions with the amino nitrogen atoms and hydroxyl oxygen atoms of the amidoximation groups to form Fe (III)-amidoximated PAN fiber complex, and the Fe content of which is mainly determined by Fe (III) ions and amidoximation groups. Fe (III)-amidoximated PAN fiber complex is found to be activated in the visible light region. Moreover, Fe (III)-amidoximated PAN fiber complex shows the catalytic activity for dye degradation by H{sub 2}O{sub 2} at pH = 6.0 in the dark, and can be significantly enhanced by increasing light irradiation and Fe content, therefore, it can be used as a new heterogeneous Fenton photocatalyst for the effective decomposition of the dye in water. In addition, ESR spectra confirm that Fe (III)-amidoximated PAN fiber complex can generate more {center_dot}OH radicals from H{sub 2}O{sub 2} under visible light irradiation, leading to dye degradation. A possible mechanism of photocatalysis is proposed.

  9. Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln3+-TiO2 surface under UV/solar light

    International Nuclear Information System (INIS)

    Devi, L. Gomathi; Kumar, S. Girish

    2012-01-01

    Graphical abstract: The surface reactive acidic sites enhances on doping with rare earth ions which facilitates efficient adsorption of the dye molecules on the catalyst surface. In addition, the nature of the dopant, its concentration and electronic configuration additionally contributes to the overall efficiency. Highlights: ► The degradation of structurally different anionic dyes under different pH conditions is reported. ► Pre adsorption of pollutant on catalyst surface is vital for efficient photocatalysis. ► Adsorption of dye on the catalyst surface depends on the substituent's attached to it. ► The dopant with half filled electronic configuration served as shallow traps for charge carriers. - Abstract: The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln 3+ (Ln 3+ = La 3+ , Ce 3+ and Gd 3+ ) doped TiO 2 at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd 3+ (0.15 mol%)-TiO 2 exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd 3+ ions. It is proposed that Ln 3+ serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

  10. Smoking-Cue Induced Brain Activation In Adolescent Light Smokers

    Science.gov (United States)

    Rubinstein, Mark L.; Luks, Tracy L.; Moscicki, Anna-Barbara; Dryden, Wendy; Rait, Michelle A.; Simpson, Gregory V.

    2010-01-01

    Purpose Using fMRI, we examined whether or not adolescents with low levels of nicotine exposure (light smokers) display neural activation in areas shown to be involved with addiction in response to smoking-related stimuli. Design/Setting/Participants Twelve adolescent light smokers (aged 13 to17, smoked 1 to 5 cigarettes per day) and 12 non-smokers (ages 13 to 17, never smoked a cigarette) from the San Francisco Bay Area underwent fMRI scanning. During scanning they viewed blocks of photographic smoking and control cues. Smoking cues consisted of pictures of people smoking cigarettes and smoking-related objects such as lighters and ashtrays. Neutral cues consisted of everyday objects and people engaged in everyday activities. Findings For smokers, smoking cues elicited greater activation than neutral cues in the mesolimbic reward circuit (left anterior cingulate (T=7.88, pbrain regions seen in adult and heavy teen smokers suggests that even at low levels of smoking, adolescents exhibit heightened reactivity to smoking cues. This paper adds to the existing literature suggesting that nicotine dependence may begin with exposure to low levels of nicotine, underscoring the need for early intervention among adolescent smokers. PMID:21185518